Assessment of a Sulfur Dioxide Based Diagnostic System in Characterizing Real
Time Oil Consumption in a Diesel Engine
by
Mark A. Jackson
B.S., Marine Engineering; United States Coast Guard Academy, 1989
Submitted to the Department of Ocean Engineering and Mechanical Engineering in
Partial Fulfillment of the Requirements for the Degrees of
MASTER OF SCIENCE IN NAVAL ARCHITECTURE AND MARINE
ENGINEERING
and
MASTER OF SCIENCE IN MECHANICAL ENGINEERING
at the
Massachusetts Institute of Technology; May 1996
© 1996 Mark A. Jackson. All rights reserved.
The author hereby grants to MIT permission to reproduce and to distribute publicly, paper
and electronic copies of this document in whole or in part.
._
"Department of Ocean Engineering May 1996
Signature of Author
Certified by_
.....
Dr. Alan J. Brown
Professor, Department of Ocean Engineering
Thesis Advisor
Certified by
Accepted by
.. _.--.,,
Dr. Victor W. Wong
Lecture Department of Mechanical Engineering
Thesis Advisor
.
leA. Douglas Carmichael, Chairman
Denartment Committee on Graduate Studies
Department of Ocean Engineering
Accepted by
A. Sonin, Chairman
Departmental Committee on Graduate Studies
Department of Mechanical Engineering
JASiSAI.Q--UETTS
.NS'!i'
rE
OF TECHNOLOGY
1
JUL 2 6 1996
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2
Assessment of a Sulfur Dioxide based diagnostic system in
characterizing Real-Time Oil Consumption in a Diesel Engine
by
Mark A. Jackson
Submitted to the Department of Ocean Engineering and the Department of Mechanical Engineering in
Partial Fulfillment of the Requirements for the Degrees of Master of Science in Naval Architecture and
Marine Engineering and Master of Science in Mechanical Engineering.
ABSTRACT
A study of oil consumption characteristics was completed using a single cylinder direct injection
diesel engine. The objectives included assessing the performance and procedures of a real time sulfur
dioxide oil consumption system and studying oil consumption including testing the repeatability and
variability through load changes, speed changes, air intake manifold pressure changes, and the performance
of various ring packs.
The testing included six matrices. Three of the matrices conducted measured the steady state speed
and load effects on oil consumption for three different ring pack configurations (Standard Ring Pack,
reduced Oil Control Ring Tension, and Inverted Scraper Ring). A matrix was conducted to measure the
effects of reduced intake manifold pressure with standard ring pack configuration. Two matrices were
conducted to monitor speed and load transients. The transient testing included alterations of speed at two
loads and the alteration of load at two speeds.
The first steady state matrix with the standard ring pack showed that the SO 2 based diagnostic
system is a viable means to measure oil consumption and is capable of delivering repeatable results. The
second steady state matrix with the reduced oil control ring tension showed an increase in oil consumption
by, on average, 10.5 times. The third steady state matrix with the inversion of the scraper ring showed an
increase in oil consumption by, on average, 6.4 times. The reduction of the intake manifold pressure to 90
kPa and 80 kPa caused increases in oil consumption by 84.2% and 165.5% respectively. This increase in oil
consumption is likely caused by the differential pressure between the cylinder and the lands during the
intake stroke. The two transient matrices showed that for small speed and load transients oil consumption
measured by the SO 2 diagnostic showed oil consumption "hump" in the positive and negative directions
depending on speed or load.
Thesis Advisor:
Alan J. Brown
Title:
Thesis Advisor:
Title:
Professor, Department of Ocean Engineering
Victor W. Wong
Lecturer, Department of Mechanical Engineering
3
(This Page Intentionally Left Blank)
4
ACKNOWLEDGEMENTS
I would like to thank the faculty at MIT Sloan Automotive Lab and that of the rest
of the Mechanical Engineering and Ocean Engineering Departments. You have made my
stay here at MIT challenging and rewarding. I would particularly like to thank Capt. Alan
Brown and Dr. Victor Wong who have helped guide me through this thesis. Also, thanks
to Prof. John Heywood for timely advise and overall perspective.
I cannot with any degree of consciousness mention anyone else before thanking
Tom Miller. Although we've known each other for many years I don't think either of us
had a clue how well we would truly end up knowing each other. Thank you for listening
to my endless banter, and for helping when the "legacy" was about to break us. I really,
couldn't have done it without you.
Richard Flaherty at Cummins Engine Company who answered my thousands of
questions and gave technical advice in solving some of my problems. Special thanks to;
Dave Fiedler of Dana Perfect Circle, Norbert Abraham and Weibo Weng also of
Cummins Engine Company.
I must thank my wife Suzanne who endured endless nights of me being the
"ultimate of crabdom". You stood by me and were always very understanding. I
appreciate that more than you could know. Thanks.
I'd like to thank all those fellow students I worked alongside with at the Sloan
Lab. To Tian Tian and Bouke Noordzij thanks for helping with those moments when my
theories started to diverge. To Mark Kiesel thanks for asking all those questions that
made me delve deeper into the understanding of the system. To Alan Shihadeh thanks for
your patience with the engine. You put your work on hold and I deeply appreciate it. To
Brian Corkum, thanks for your assistance in, well, just about everything. I'd also like to
thank all the rest of the sloan students and staff who helped make life more pleasant and
enjoyable.
I'd also like to thank all of the Coast Guard and Navy students and staff who
made life more interesting, especially during those five class semesters. Lee, Tom Moore,
Chris Trost, Chris Warren, John D., Jim T., Dan P., Joc, Tim, Rob, Mike and Bob.
This project was primarily sponsored by the Maritime Administration (MARAD)
with support from the United States Coast Guard under contract DTMA 91-95-00051.
Special thanks to Dan Leubecker of MARAD and Dr. Alan Bentz of the USCG R&D
Center for their guidance and support. This project was also supported by the Consortium
of Lubrication in Internal Combustion Engines, whose members include Dana
Corporation, Peugeot, Renault, and Shell Oil Company.
5
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6
TABLE OF CONTENTS
ABSTRACT
ACKNOWLEDGEMENTS
3
5
TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
7
9
11
ABBREVIATIONS
Chapter 1 MOTIVATION
13
15
1.1 Introduction
15
1.2 Previous Work
1.3 Oil Consumption Sources
1.4 Oil Consumption Measurement Techniques
16
16
17
1.5 Objectives
18
Chapter 2 EXPERIMENTAL APPARATUS
19
2.1 Engine
19
2.2 SO 2 Diagnostic
22
Chapter 3 TESTING PROCEDURE
29
3.1 General Overview of Testing Procedure
3.2 Testing Procedure for the Standard Ring Pack
3.21 Test Matrix 1
29
33
33
3.22 Procedure
34
3.23 Matrix 1 - Engine Specifics, Controls and Variables
37
3.3 Testing
3.31
3.32
3.33
Procedure Matrix a - Altered intake pressure
TestMatrix la
Procedure
Matrix la- Engine Specifics, Controls and Variables
3.4 Testing
3.41
3.42
3.43
3.5 Testing
3.51
Procedure Matrix 2
Test Matrix 2
Procedure
Matrix 2 - Engine Specifics, Conti rols and Variables
Procedure Matrix 3
Test Matrix 3
3.52 Procedure
3.53
3.6 Testing
3.61
3.62
3.7 Testing
3.71
3.72
Matrix 3 - Engine Specifics, Conti rols and Variables
Procedure Matrix R
Test Matrix R
Procedure
Procedure Matrix L
Test Matrix L
Procedure
Chapter 4 TEST CALCULATIONS
4.1 Determination of Engine Oil Consumption
I
7
39
39
39
39
40
40
40
41
42
42
42
43
43
44
44
45
45
45
47
47
Chapter 5 RESULTS AND ANALYSIS
5.1 Results of SO2 Uncertainty Analysis
5.11
5.12
5.13
5.14
Effect of Bypass Flow Rate
Effect of Various Sample Line Temperatures
Electronic Drift of Detector Output
Partially Completed Tests
5.2- Results for the Standard Ring Pack (Matrix 1)_
5.21 Matrix 1: Steady State Speed and Load Effects on Oil
53
53
53
56
57
59
61
61
Consumption
5.22 Variability of Matrix I During Steady State Operation
5.3 Results for Various Intake Pressures (Matrix I a)
5.31 Results for Matrix la: Steady State Oil Consumption at
62
63
63
Various Intake Pressures
5.32 Results from Gas Flow and Ring-Dynamics Simulation
5.4 Results for Reduced Oil Control Ring Tension (Matrix 2)
5.41 Results for Matrix 2
5.42 Variability of Matrix 2 During Steady State Operation
5.5 Results for Inverted Scraper Ring (Matrix 3)
5.6 Results for Matrix R
5.7 Results for Matrix L
Chapter 6 CONCLUSIONS
64
65
65
66
67
68
74
81
Chapter 7 RECOMMENDATIONS
85
REFERENCES
91
Appendix A TESTING DATA SHEETS
Appendix B UNCERTAINTY ANALYSIS RESULTS
93
97
Appendix C MATRIX 1 RESULTS
Appendix D MATRIX a RESULTS
Appendix E MATRIX 2 RESULTS
103
117
128
Appendix F MATRIX 3 RESULTS
135
Appendix G MATRIX R RESULTS
Appendix H MATRIX L RESULTS
144
161
8
LIST OF FIGURES
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
2-1
2-2
2-3
2-4
2-5
3-1
7-1
A- 1
A-2
A-3
FigureA4
Figure B- 1
Figure B-2
Figure B-3
Figure B-4
Intake System
Exhaust System
Oil Consumption Sampling System
Furnace Tube Setup
Bypass Flow Line Diagram
ISO 8178-4 Test Cycle Different Engine Applicatiions
20
22
Recommended Cell Air alteration
Overall Test Matrix
86
93
Daily Data Sheet
Oil Consumption Pre-Run Data Sheet
Oil Consumption Testing Data Sheet
Various Bypass Flow Rates
Sample Line Test (Line Temp @ 600°F)
Sample Line Test (Line Temp @ 950F)
94
J
Figure C-6
Oil Consumption at 1200 RPM and Low Load
Oil Consumption at 1200 RPM and Med Load
Oil Consumption at 1200 RPM and High Load
Oil Consumption at 2400 RPM and Low Load
Oil-----Consumption
___ at 2400 RPM and Med Load
a-_ __
Oil Consumption at 2400 RPM and High Load
Oil Consumption at 3200 RPM and Low Load
Oil Consumption at 3200 RPM and Med Load
Oil Consumption at 3200 RPM and High Load
Results: Test Matrix 1a
OC at 1200 RPM and 5 Nm Various Press. (individual runs)
OC at 1200 RPM and S Nm Various Press. (averages)
OC at 1200 RPM and 5 Nm (90 kPa)
OC at 1200 RPM and 5 Nm (80 kPa)
Gas Flow at 1200 RPM and 5 Nm (101 kPa)
Gas Flow at 1200 RPM and 5 Nm (90 kPa)
Gas Flow at 1200 RPM and 5 Nm (80 kPa)
Figure
Figure
Figure
Figure
Figure
Figure
Figure
C-7
C-8
C-9
C- 10
C- 11
C- 12
C-13
Figure C-14
Figure D-
Figure D-2
Figure D-3
Figure D-4
Figure D-5
Figure D-6
Figure D-7
Figure D-8
Figure D-9
Figure D- 10
Figure D-1 1
........
--
97
99
Figure C-5
.......
95
96
100
101
102
103
104
_
J
--
30
98
Oil Consumntion comparison with previous data
....
27
-
Figure C-4
B-5
B-6
C- 1
C-2
C-3
26
-
Interval Test Series #1
Interval Test Series #2
Interval Test Series #3
Results: Test Matrix 1
at Steady State (individual runs)
Oil Consumption
~~rOil Consumption at Steady State (averages)
Oil Consumption at Steady State (averages)
Figure
Figure
Figure
Figure
Figure
23
105
-
106
107
108
109
110
-
..........
rosm o
-
-
-
-
-
111
-
La
.t240RP.ad..
-
-
-
-
.
Mass Flow through Top Ring Gap
Intake Stroke 2nd Land Pressures
Peak Pressures at Various Intake Pressures
9
112
113
114
115
116
117
118
119
120
121
122
123
124
125
-
126
127
LIST OF FIGURES (continued)
Figure E- 1
Figure E-2
Figure E-3
Figure E-4
Figure E-5
Figure E-6
Figure E-7
Figure F- 1
Figure F-2
Figure F-3
Oil Consumption with Inverted Scraper (averages)
137
Figure F-4
OC
OC
OC
OC
138
139
140
141
Figure F-5
Figure F-6
Figure F-7
Figure F-8
Figure F-9
Figure G- 1
Figure G-2
Figure G-3
Figure G-4
Figure G-5
Figure G-6
Figure G-7
Figure G-8
Figure G-9
Figure G-10
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
G- 11
G- 12
G- 13
G- 14
G- 15
G- 16
G-17
H- 1
H-2
H-3
H-4
H-5
H-6
H-7
H-8
Results: Test Matrix 2
128
Oil Consumption at 52% OC Ring (individual runs)
129
Oil Consumption at 52% OC Ring (averages)
OC at 1200 RPM and 5 Nm with 52% OC Ring
OC at 1200 RPM and 10 Nm with 52% OC Ring
OC at 2400 RPM and 5 Nm with 52% OC Ring
SO2 at 2400 RPM and 10 Nm with 52% OC Ring
Results: Test Matrix 3
Oil Consumption with Inverted Scraper (individual runs)
130
131
132
133
134
135
136
at 1200 RPM
at 1200 RPM
at 2400 RPM
at 2400 RPM
and
and
and
and
5 Nm with Inverted Scraper
10 Nm with Inverted Scraper
5 Nm with Inverted Scraper
10 Nm with Inverted Scraper
OC Comparison for various Ring Pack Designs
OC Comparison for various Ring Pack Designs
142
143
Speed
Speed
Speed
Speed
Speed
144
145
146
147
148
Transient
Transient
Transient
Transient
Transient
2400-3200
2400-3200
2400-3200
2400-3200
2400-3200
at 5 Nm #1
at 5 Nm #2
at 5 Nm #3
at 5 Nm #4
at 10 Nm #1
Speed Transient 2400-3200 at 10 Nm #2
Speed Transient 2400-3200 at 10 Nm#3
Speed Transient 2400-3200 at 10 Nm #4
Speed Transient 3200-2400 at 5 Nm #1
Speed Transient 3200-2400 at 5 Nm #2
Speed Transient 3200-2400 at 5 Nm #3
Speed Transient 3200-2400 at 5 Nm #4
Speed Transient 3200-2400 at 10 Nm#l
Speed Transient 3200-2400 at 10 Nm #2
Speed Transient 3200-2400 at 10 Nm #3
Speed Transient 3200-2400 at 10 Nm #4
Speed Transient 3200-2400 at 10 Nm #5- __
,
Load Transient (5-10 Nm) at 2400 RPM #1
Load Transient (5-10 Nm) at 2400 RPM #2
Load Transient (5-10 Nm) at 2400 RPM #3
Load Transient (5-10 Nm) at 2400 RPM #4
Load Transient (5-10 Nm) at 3200 RPM #1
Load Transient (5-10 Nm) at 3200 RPM #2
Load Transient (5-10 Nm) at 3200 RPM #3
Load Transient (5-10 Nm) at 3200 RPM #4
10
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
-
-
-
165
166
167
168
LIST OF FIGURES (continued)
Figure H-9
Load Transient (10-5 Nm) at 2400 RPM #1
Load Transient (10-5 Nm) at 2400 RPM #2
Figure H- 11 Load Transient (10-5 Nm) at 2400 RPM #3
Figure H-12 Load Transient (10-5 Nm) at 2400 RPM #4
Figure H-13 Load Transient (10-5 Nm) at 2400 RPM #5
Figure H-14 Load Transient (10-5 Nm) at 3200 RPM #1
Figure H- 1S Load Transient (10-5 Nm) at 3200 RPM #2
Figure H- 16 Load Transient (10-5 Nm) at 3200 RPM #3
Figure H- 17 Load Transient (10-5 Nm) at 3200 RPM #4
-
-
Figure H- 10
11
169
170
171
172
__
173
174
175
-
-
-
176
177
LIST OF TABLES
Table 3-1
Table 3-2
Table 3-3
Table 3-4
Table 3-5
Table 3-6
Table 3-7
Table 3-8
Table 3-9
Table 3-10
Table 3-11
Table 3-12
Table 3-13
Table 3-14
Table 3-13
Table 5-1
Table 5-2
Table 5-3
Table 5-4
Table 5-5
Table 5-6
Table 5-7
Table 5-8
Table 5-9
Table 5-10
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
5-11
5-12
5-13
5-14
5-15
5-16
5-17
5-18
5-19
5-20
7-1
Differences in Test Matrices
Test Matrix 1
Typical Run of Matrix
31
33
36
37
38
38
39
-
Diesel Fuel Characteristics
Ring Specifications
w
_
Matrix 1 Variable Specifics
A
Matrix la
-
40
Matrix 2
Typical
Run of Matrix 2
.
41
42
42
44
Modified Oil Control Ring Specifications
Matrix 3
--
__
Matrix R
Typical
Run of Matrix R
,.
Matrix L
45
45
46
Typical Run of Matrix L
Uncertainty Tests
Results
Results
Results
Results
Results
Results
Results
Results
Results
Results
-
Bypass Flow Test
Sample Line Test
Interval Test #1
Interval Test #2
Interval Test #3
Matrix 1
Matrix a
Matrix 2
Matrix 3
Matrix R - Test R 1BC 1A
L
-
S
Results Matrix R - Test R1BC2A
Results Matrix R - Test RICB 1A
Results
Results
Results
Results
Results
Results
61
-
63
65
67
69
-
-
4
-
-
-
-
Results Matrix L - Test LIC21A
12
-
71
I-
Test R I CB I A area of hui
Matrix L - Test L 1B 12A
Test L 1B 12A area of hun
Matrix L - Test L 1C 2A
Matrix L - Test L1 B2 A
Test L 1B2 I1Aarea of hun
Recommended Variables to Mon"
.
53
54
57
58
58
59
-
-
-
-
-
-
72
73
76
76
77
78
79
79
88
ABBREVIATIONS
UNITS
DEFINITION
SYMBOL
a
# of carbon atoms per fuel molecule
AIRvolt
Meter voltage output due to sulfur in ambient air
b
# of hydrogen atoms per fuel molecule
BTDC
Before top-dead-center
COmol
Carbon monoxide concentration in exhaust
% molar
CO2mol
Carbon dioxide concentration in exhaust
% molar
EXHtot
Exhaust flow rate
g/hr
FUELppm
Sulfur content in fuel
ppm by wt
H 2Oair
Water in ambient air
% by wt
H2Ocombmol
Water in exhaust due to combustion
% molar
H2Ocomb
Water in exhaust due to combustion
% by wt
H2Oexh
Water in exhaust
% by wt
H2Owf
Fraction of water in air
volt
Relative air to fuel ratio
Lubes
Sulfur content in lubricating oil
% by wt
MWexh
Molecular weight of exhaust gases
g/g-mole
OC
Oil Consumption
gg/cyl-cycle
Pa
Density of air
g/m 3
Pf
Density of fuel
Sexh
Sulfur dioxide flow rate in exhaust
g/hr
SAIMPvolt
Detector output for OC reading
volt
SOC
Specific oil consumption
g/kW-hr
SPANppm
Span gas ppm by weight
ppm by wt
SPANvolt
Output voltage from the detector due to span gas
volt
T
Temperature
Celsius
Va
Volumetric air flow rate
m3 f/hr
g/cc
13
Vf
Volumetric fuel flow rate
y
Relative hydrogen to carbon ratio
cc/hr
14
Chapter 1 MOTIVATION
1.1 Introduction
The United States has become very conscious of the ever growing pollution
problems existing throughout the country. Strict regulations have been implemented by
the EPA on heavy-duty diesel particulate emissions. The standard particulate rate for
1996 urban buses is 0.05 g/bhp-hr [20]. It also has become a concern in the marine
environment where emissions up to this point have not been regulated. In states such as
California cases have been noted of officials forcing ships to be towed out to sea 12 miles
before allowing the ship to start their engines. The Maritime Administration (MARAD)
has shown interest in knowing the relationship between lubricating oil consumption and
particulate emission rates. The amount of lube oil derived particulate of the overall
particulate rate was reported by Laurence [1] to be between 24-33% in a small light-duty
engine. With a significant portion of the particulate rate coming from the oil more
analysis is necessary to further the understanding of the relationship. In the past decade
new and improved methods have been introduced to study lubricating oil consumption in
engines. Most of the older methods have been "time-averaged". They required many
hours of study with results which had many errors. The sulfur dioxide tracer technique is
a "real-time" measurement system. It responds as the engine oil consumption changes.
Cummins Engine Company designed and built a real time oil consumption diagnostic
which utilized the SO2 tracer technique. In the spring of 1995 Cummins loaned this
apparatus to M.I.T. for the purposes of research.
First uses of the system showed that oil consumption at specific speeds and loads
on various engines had unexplained variability. The newness of the system left some
uncertainty as to the cause of this variability. The SO 2 diagnostic, although an excellent
method to measure oil consumption, was untested as to its limitations and possible errors
introduced by the diagnostic itself.
15
In the past, attempts to take oil consumption and particulate data simultaneously
had been thwarted for various reasons. The relationship between the two is necessary to
fully understand what the effects of altering oil consumption has on particulate emissions.
1.2 Previous Work
In recent history many studies of oil consumption have been completed at M.I.T..
Most recent studies included the use of a tritium radio-tracer technique, by Lusted [3] and
by Hartman [4], and a sulfur dioxide tracer technique, by Schofield [9], to measure oil
consumption rates. All of these studies revealed large unexplained oil consumption
variability at particular speeds and loads. Lusted [3] studied the oil consumption behavior
in a production four cylinder spark ignition engine and found a variability of greater than
20% at one specific speed and load. Hartman [4] conducted similar oil consumption
measurements on a single cylinder Kubota diesel engine and his results showed a large
unexplained variability at one speed and load. Schofield [9] studied the oil consumption
behavior of a Ricardo Hydra single-cylinder direct injection naturally aspirated diesel
engine. Schofield used an SO2 diagnostic to measure the oil consumption and found a
similar variability at one specific speed and load. Thus far, no justification has been
determined to describe this phenomena, but it has been hypothesized by Schofield that
this large variability may be due to ring dynamics within the cylinder.
1.3 Oil Consumption Sources
Hill [6] describes four primary paths of oil consumption in diesel engines.
1. Piston-ring-liner system
2. Overhead valve seals
3. Crankcase ventilation system
4. Oil pan, crankcase, turbocharger, and other component gasket seals
16
In this study, since the crankcase ventilation is not coupled with the air inlet and there is
no turbocharger, the oil consumption can primarily be attributed to the piston-ring-liner
system and the overhead valve seals. These two sources can be separated for oil
consumption measurements utilizing a separate closed loop valve train oil system. If a
"zero sulfur" oil is utilized in the valve train then any valve seal oil consumption would
be masked using the SO2 technique. This study is focusing on overall oil consumption
and not on any particular sources. It is also coupled with a study on particulate emissions.
Since the source of the emission is irrelevant, the isolated valve train is not used.
1.4 Oil Consumption Measurement Techniques
Oil consumption measurement methods have varied greatly over the past 50 years.
There are two primary categories of measurement systems, time-averaged and real-time.
Up until the early '90's the most common method of measurement was time-averaged. In
those cases any transient behavior was hidden as was any true variability.
The most simplistic method to measure oil consumption consists of the "weight"
method. The weight method entails the weighing of the oil prior to running the engine
and then again after running the engine a known time period. This method requires a time
constant which is "very long" for any degree of accuracy. The longer the time run the
better the results. This method has advantages in that it doesn't require any special
apparatus nor does it require additives or special fluids which might alter the operation of
the engine itself. Its disadvantages are that it requires such long periods of running to get
one data point and it is unknown what goes on in the engine during those times.
Another method is the tritium radio-tracer technique. The radio-tracer technique
requires a radioactive dye to be placed in the oil which is "traced" over a "long" time
period (approx. 10 min). This method decreases the time constant significantly but it still
lacks any real-time capability. Its advantages are that it doesn't require that the engine be
run for days, but due to the difficulty in actually measuring the radioactive dye in the
exhaust it requires "long" time constants. It also has the disadvantage of requiring
17
radioactive material in the engine to run these tests. This requires special certification and
special caution in all aspects of testing.
A sulfur dioxide method was developed in the late 80's and early 90's. Its mode
of operation is to analyze the exhaust gas of an engine. A "zero sulfur" fuel and a
relatively high sulfur oil are run in the engine. Sulfur dioxide found in the exhaust is
produced from the lubricating oil which is consumed. A system was prototyped by
Cummins Engine Company and loaned to MIT for use. This diagnostic was used
extensively by Schofield [9] in measuring steady state results.
1.5 Objectives
The large oil consumption variability found in many of the previous works was
hypothesized as being due to ring dynamics, the diagnostic equipment, or other
undetermined factors. This thesis work, sponsored by a joint Maritime Administration
(MARAD) and Coast Guard committee will focus on meeting the following objectives:
1. Providing oil consumption characteristics for different ring pack
configurations and air intake manifold pressures.
2. Assessing the SO 2 diagnostic as a possible source of oil consumption
variability.
3. Eliminating or confirming ring dynamics as a contributor to oil consumption
variability.
A Ricardo Hydra single-cylinder direct injection naturally aspirated diesel engine
configured by G. Cussons Ltd. is used as the test bed for the study.
18
Chapter 2 EXPERIMENTAL APPARATUS
2.1 The Engine
The engine used in this experimental study was a Ricardo Hydra single-cylinder
direct injection naturally aspirated diesel engine configured by G. Cussons Ltd. It was
setup in a research test cell with separately mounted oil and water pumps. The engine
startup and load monitoring were accomplished utilizing a Dynamatic dynamometer and
variable speed coupling mounted on the engine drive shaft. Fuel flow, air flow, load and
engine speed were each controlled independently. Engine specifics are listed below.
Manufacturer:
G. Cussons Ltd.
Model:
Hydra single cylinder research engine
Bore:
80.26 mm
Stroke:
88.9 mm
Cylinders:
1
Swept Volume:
0.4498 1
Compression Ratio:
19.8:1
Aspiration:
Natural/Throttled
Rated Speed:
4500 RPM
Due to the limitations of the dynamometer, the maximum speed of the engine in
the current design is 3400 RPM. The manufacturer suggests that the engine's power be
limited by the exhaust smoke. The maximum power output is 8 kW at a smoke level of 4
Bosch units at 4500 RPM.
The engine's speed was set using the dynamometer controller. The controller is
capable of running at a set speed or a set load depending on the selected operating mode.
When the engine's speed was controlled the load was adjusted by altering the fuel flow.
The dynamometer uses resistive torque to control the speed which was set at the
controller. This generates oscillations in the load. These fluctuations varied with
19
operating condition, and ranged from 10-20% throughout the range of operation. In this
work, when load is referenced it refers to the average load. The load was monitored by a
load cell which was calibrated prior to the commencement of testing and monitored
thereafter. The load cell was attached directly to the controller and had an outlet which
allowed for monitoring via the data acquisition system.
The dynamometer controller was never set to the "load" operating mode during
testing. When in that mode the dynamometer controller maintains a constant load. This
causes the engine to slow down or speed up depending on the fuel flow rate. It was too
difficult to maintain a steady engine speed in this mode for any kind of steady state to be
reached.
The fuel flow was controlled remotely by a servo motor. The fuel flow was
monitored using a "paddle wheel" flow meter. The flow meter was calibrated prior to use.
The fuel injection timing was also controlled independently. The cylinder pressure was
monitored during operation via an oscilloscope to ensure timing was set to maximize
torque and engine performance.
The intake was equipped with a valve so that the air intake manifold pressure
could be altered. A mass flow meter and a pressure transducer were placed in the intake
line to monitor pressure and flow. Both instruments were calibrated prior to use. A
diagram of the intake system can be seen in Figure 2-1.
Air Flow
ermocouple
Filter
Ex
Fig 2-1
20
Thermocouples were placed at several locations on the engine to monitor engine
operating condition. Thermocouple locations are listed below:
Description
Thermocouple
Number
1
VALVE OIL
2
FUEL IN
3
4
OIL INTO BLOCK
COOLANT TANK
5
6
7
EXHAUST MANIFOLD
AIR INTO HEAD
EXHAUST MIXING TANK
8
9
10
OIL OUT OF SUMP
INOPERATIVE
OIL INTO THE BLOCK
11
COOLANT TANK (ENGINE)
12
INOPERATIVE
13
14
15
COOLANT INTO ENGINE
CYLINDER COOLANT OUT
HEAD COOLANT OUT
16
INOPERATIVE
The exhaust system was modified to facilitate the taking of all data. A 1/4 in
stainless steel line was introduced right after the exhaust manifold to extract a sample for
the SO2 diagnostic. A mixing tank is approximately one meter downstream from the
exhaust manifold. At the mixing tank fittings were added to allow for the monitoring of
the gaseous emissions content by two methods. The two methods were the ENERAC
2000 and the gas cart. A comparison was made of these by Miller [21]. After the mixing
tank the exhaust gas was funneled to the dilution tunnel for particulate sampling or the
exhaust trench for removal from the facility. The particulate sampling system is described
by Miller [21]. The valve (labeled #
in Fig 2-2) which leads to the trench was used as a
back pressure valve. This will be described in more detail in the description of the SO2
diagnostic.
21
To S02
System
Shop Air
ution
nnel
,Particulate
Filters
To Trench
Fig 2-2
The oil usedin the engine was a special 30W oil made by Lubrizol. This oil was
chosen for its specific performance characteristics. This oil, when compared to most
standard oils, has an even sulfur distribution throughout the distillation range of the oil.
This was also noted by Ariga [7]. The even sulfur distribution ensures that for any
operating condition (cylinder temperatures) an equivalent amount of sulfur is released.
This makes results more precise and comparable over various speeds and loads.
2.2 The SO 2 Diagnostic
The oil consumption was measured using a pyrofluorescence sulfur dioxide
testing diagnostic developed by Cummins Engine Company, Inc. The principle of this
system is to trace the sulfur in the oil through the combustion process into the exhaust
22
gas. This is made possible by using a "zero sulfur" oil and lubricating oil which contains
sulfur. The system is diagrammed in Fig 2-3.
The diagnostic was changed multiple times throughout testing. As one of the
objectives was to assess whether the diagnostic was the cause of the variable oil
consumption, changes were made in an attempt to improve the functionality of the
diagnostic. A brief description of the diagnostic in its initial state sets the foundation for
the alterations which were made.
Lch
- valve
Fig 2-3
Immediately following the exhaust manifold the exhaust gas is drawn through a
1/4
inch stainless steel tube (sample line). The sample line leads the gas through a solenoid
valve which allows for the isolation of the exhaust gases from the system during
calibration. Immediately following the solenoid valves is the furnace which is heated to
1000 ° C. The furnace is to ensure combustion of all particles in the exhaust gas. After the
furnace the gas flows through a 60gm filter which removes any remaining large particles,
which escaped combustion in the furnace, prior to entering the analyzer.
Heated lines maintain the temperature of the gas above the point of condensation.
Immediately prior to the analyzer a pair of membrane dryers remove the 3-12% water in
the exhaust directly from the vapor phase without condensing the moisture first.
23
The sample is then mixed with ozone to oxidize any NO to NO 2 . The sample is
then analyzed by a pulsed fluorescent ambient SO2 detector. The detector's linear DC
voltage output is recorded by a computer data acquisition system and a linear chart
recorder.
The concentration readings were real-time measurements of the SO2 concentration
and were proportional to the oil consumption of the engine. The details of the calculation
of oil consumption from the voltages can be found in Chapter 4.
The real-time oil consumption (RTOC) system, being a prototype, was initially
run at the original specifications. Those specifications are outlined by Schofield [9]. The
initial focus in regard to the diagnostic was to determine whether any of the variability
associated with Schofield's data was due to the system itself. Through multiple
conversations with members of the Lube Oil consortium and Richard Flaherty of
Cummins Engine Company it was theorized that part of the variability might be caused
by the sample line being at too low of a temperature and too great a length (--42 in for
Schofield's setup). In the literature generated about the system it was stated, "keep the
sample line temperature above 600°F". The vaporization temperatures of typical oil range
from 600-900°F (Flaherty[5]). It was decided to do two things; I1)Increase the
temperature of the sample line above the vaporization/condensing
point of the oil
(=950°F), and 2) To shorten the length of the sample line. As the length of the line
increased the more oil was capable of becoming resident in the lines.
The sample line was installed with a length of 18 inches and temperatures were
increased to greater than 950°F. The temperature increase included not only the sample
line but also the line between the solenoid valves and the furnace. Another modification
which was along similar lines was the addition of insulation at the exhaust manifold. It
was insulated only to the sample line and no further. This was done in an attempt to
ensure that as much of the heat of the exhaust was maintained.
24
The system was operated in this configuration for approximately 15 test runs. At
that time it became a concern that the exhaust back pressure requirements might be
excessive. The system requires that pressure be applied to the exhaust system to get flow
to the analyzer. This was done by closing the back pressure valve on the exhaust (Valve
#1 on Fig 2-2). The literature stated that 1.5 liters/min (/m) was required as a "bypass
flow" to ensure that only exhaust gas was received at the SO2 detector and an accurate
reading was given. The bypass (see Fig 2-3) is a "vent" for the analyzer. The exhaust gas
in the analyzer itself needs to be at atmospheric pressure. For this reason the bypass flow
line was added to reduce or "vent" any excess pressure. The bypass line was periodically
monitored for flow using a "floating ball" flow meter installed with the system. Due to
this requirement of 1.5 1/m bypass flow a pressure transducer was installed in the exhaust
system following the exhaust manifold, and prior to the sample line (see Fig 2-3) to
monitor the back pressure on the engine. At the same time modifications to the sample
line location were made. Initially the sample line was attached to the exhaust manifold
perpendicular to the flow of the exhaust. It was chosen for ease of operation and it
enabled us to have a "short" sample line. With the concern over back pressure it was
decided that the use of the engines flow would decrease the need to create pressure in the
exhaust line. The furnace and other apparatus were moved so that a more "direct" sample
line could be installed. The sample line was placed such that the exhaust gas velocity was
utilized in increasing flow (see Fig 2-4). No back pressure measurements were taken prior
to the sample line change. For this reason it is unknown whether the new location
improved the flow and if so, to what degree.
While repositioning the furnace the glass furnace tube was broken. This tube was
replaced several times during this operation and it became apparent that it was a weak
link in the system. The slightest misalignment caused a bending moment on the tube and
it would break. The engine's vibration during startup and shutdown also caused
breakage's to occur. A revised "bracing" system was designed and implemented.
Previously, both ends of the tube were connected to stainless steel swagelock fittings.
25
These fittings were rigidly mounted to the furnace by steel braces. With alignment being a
problem it was decided that if the ends of the tube were mounted to flexible tubing the
tube would "float" in the furnace and would not be susceptible to misalignment or
vibration problems. It was decided to install this tubing only on the downstream end due
to a concern that oil and combustion particles might accumulate in the corrugations of the
flexible tubing prior to the furnace. This tube was installed as shown in Figure 2-4.
Furnace Tube Setup
Riou
COU]
.
Fig 2-4
After the new flexible tubing was installed the downstream end was capable of
moving when necessary, but only minutely due to the packing material around the tube
itself as it exited the furnace. This arrangement worked satisfactorily with no more glass
tubes being broken.
The previous concern over maintaining at least 1.5 /m was erroneous. The
previous explanation was that the analyzer would utilize
1/mand the additional flow
(then thought to be 0.5 /m with a 1.5 /m bypass) was to ensure that only sample gas was
reaching the analyzer. This additional flow is not 0.5 I/m, but actually all of the bypass
flow is additional flow. A simplified line diagram can be seen in figure 2-5 which shows
the flow. If the analyzer always draws 1 /m and the bypass is 1.5 l/m then the sample line
26
flow must be at least 2.5 /m assuming no losses. A sample line flow of only 1.5 1/m is
necessary.
Sample Line
Flow
I
1 1/m
..ap- - __
- -4.
%
x,.
Analyzer
.g2f
1.3 I/
Bypass Flow
Fig 2-5
It could be theorized that the excess bypass flow, an extra liter/min, would not
have any effect, but, it is possibly detrimental to the operation of the diagnostic. Any
reading at the bypass at all would ensure that the analyzer is getting a pure sample. The
excessive flow(1.5 Url/m)
may have been detrimental in that it was causing the analyzer to
become pressurized. The bypass flow was designed as a vent to ensure that the analyzer
was at atmospheric pressure. Too much flow causes the bypass to be an inadequate vent.
The uncertainty analysis (to be discussed in more detail in Chapter 5) showed that the
change from 1.51/m to 0.5 U/mbypass flow altered the S02 concentration of a known span
gas by 10%. There was also "unsteady" behavior at the higher bypass flow rates and none
at the lower flow rates. Overall, if the bypass is maintained at either level during
calibration and then during testing the results should be equivalent. However, the higher
flow rates required a much higher pressure be placed on the exhaust system. This could
be avoided by using the lower flow rates.
Following the installation of the flexible tubing and the new furnace tube it was
noticed that the filters located after the furnace were clogging with soot more readily and
the furnace exit temperature was lower than before. The furnace tubes are filled with a
quartz substance. It was believed that the new furnace tube was not as tightly packed as
the previously used tubes. For this reason the gas had less surface area to come in contact
within the tube and the temperature of the gas was not getting to the desired level. New
tubes were ordered. A change in design was made which increased the diameter of the
27
tube from 1 to 2 inches. This would increase the time the gas spent in the tube by four
times. With the new tubes in place the soot found in the filters was eliminated and the
exit temperature of the furnace was increased back to previous levels. No comparisons
were made of previous tubes and current tubes for exact change in exit temperatures or
soot accumulation. The system has been modified (i.e. distance to thermocouple, flexible
tubing, etc..) such that the study would prove inconclusive results.
At one point during testing it was detected that the signal coming from the
analyzer was erratic. The analyzer itself was faulty and it was necessary to replace the
lamp and the socket for the lamp. A check of the lamp voltage should be made
periodically to ensure proper functioning of the lamp.
The data acquisition system utilized was a 486/66 MHz computer with an Analog
to Digital card inserted. It was capable of monitoring a maximum of six channels
(normally eight, but two were found to be inoperative). The computer was set up to
acquire real-time SO2 concentration, Engine Speed, Engine Torque (Load), Fuel Flow,
Air Flow, and CO2 concentration of the exhaust gas. The signals were converted using
Global Lab software and then input into an Excel spreadsheet for conversion to oil
consumption.
The exhaust gases were monitored by two different sources, the MIT gas cart and
the ENERAC 2000. The gas cart was calibrated on a daily basis. The exhaust gases CO,
CO 2 , NO and NOx were monitored manually. The ENERAC 2000 is a portable exhaust
gas measurement system. Its results were not used for any of the oil consumption
calculations. For a comparison between the ENERAC 2000 and the gas cart see Miller
[21].
28
Chapter 3 TESTING PROCEDURE
3.1 General Overview of the Testing Procedure
This chapter presents the testing procedure for the oil consumption data. The
actual testing was categorized into five matrices, 1, la, 2, 3, L and R. All of the matrices
used zero sulfur diesel and Lubrizol 30W oil. Matrices 1-3 were generated in an attempt
to match the typical duty cycle of a marine diesel engine operating near land (harbor). In
order to determine what a "complete" marine diesel duty cycle would be, ISO 8178 Part 4
"Reciprocating Internal Combustion Engines- Exhaust Emission Measurement" was
evaluated. The test cycle for different engine applications as outlined in ISO 8178-4 are
shown in Figure 3-1.
Cycle Definitions are described as follows:
Cycle
Description
A
Reference cycle for vehicle engines
B
Universal cycle, applications similar to on -road service
C1
Off-road vehicles and industrial equipment, medium and high load
C2
Off-road vehicles and industrial equipment, low load
D
Constant speed applications, power plants
D2
Constant speed applications, generator sets with intermittent load
E1
Marine engine applications, pleasure craft engines
E2
Marine applications, constant-speed engines for ship propulsion
E3
Marine applications, heavy-duty propulsion engines
F
Locomotive applications
G1/G2
Small engines, utility lawn and garden
G3
Small engines, hand held equipment
29
-
~
-
~
~
~
~
~
~
~
_
ISO 8178-4 Test Cycle for Different Engine Applications
Idle
160Percent
of Rated Speed
Cycle
I Rated Speed
Percent Load
0
10
25
50
75
100
10
25
50
75"
' 100
A
0.25
0.08
0.08
0.08
0.08
0.25
0.02
0.02
0.02
0.02
0.10
B
0.25
0.08
0.08
0.08
0.08
0.25
0.02
0.02
0.02
0.02
0.10
C1
C2
Dl
D2
F
GI
u/I-'%
G3
El
E2
E3
I%Speed/%Load/Wt
63/25/0.15
180/50/0.15
91/75/0.5
]100/100/0.2
Fig 3-1
The duty cycles considered to be applicable for simulation of low speed marine
diesel engine operations were cycle E2 (Marine Applications, constant speed engines for
ship propulsion) and cycle E3 (Marine Applications, heavy-duty propulsion engines).
Cycle E2 applies to constant speed diesel engines and is not applicable to this study. The
unmodified version of the E3 duty cycle would require four engine test speeds and loads
-
as shown in Figure 3-1. However, time constraints demanded that the scope of this study
be limited to ensure ample time for data analysis. Therefore, a modified version of the E3
cycle was selected to model operating conditions for low speed marine diesel engines.
The lowest recommended test speed for the E3 duty cycle, 63% of maximum, does not
adequately model near land or maneuvering operating conditions. For this reason, an
"idle" speed was added at 35% of maximum rated speed (1200 RPM). The Ricardo Hydra
30
engine is a small bore, high speed diesel engine and the intent of this study is to model
low speed marine diesel engines. For this reason, high end test speeds of 70% and 97%
(2400 and 3200 RPM) vice 90%, 91% and 100% of maximum rated speed were
incorporated. These chosen values match the work done by Schofield [9] and Ford [10],
which is ideal for evaluating repeatability of test results, and they sufficiently cover the
suggested E3 duty cycle test speeds.
The modified E3 duty cycle utilized in this study includes three test loads vice
two. -xmid-range test load was added to provide a more complete range of loading
conditions. This approach meets the requirements for this study and sufficiently
incorporates the guidance of ISO 8178 Part 4.
In addition to the modifications mentioned above, air intake manifold pressure
was varied for the low speed low load condition. This was to obtain a baseline indication
of its effects. Two alternative ring pack configurations were chosen to include a reduced
oil control ring tension and an inverted scraper ring. A summary of all six test matrices
and their primary differences is given below in Table 3-1.
Matrix
Ring Configuration
Intake Pressure
Test Condition
I
Standard
Atmospheric
Steady State
la
Standard
80 kPa, 90 kPa
Steady State
2
50% OC Ring Tension
Atmospheric
Steady State
3
Inverted Scraper Ring
Atmospheric
Steady State
R
Standard
Atmospheric
Speed Transient
L
Standard
Atmospheric
Load Transient
Table 3-1
Test Matrices , a, 2, and 3 were all conducted in conjunction with particulate
testing completed by Miller [21]. Tile transient tests for speed and load were done in
between steady state tests, but no particulate samples were taken. The engine was
overhauled twice to reconfigure the ring pack. Re-assembly of the engine was done such
31
that the engine was as close to the original configuration as possible. No alterations were
made other than the rings with the exception of the hydrocarbon deposits which had builtup on the cylinder liner. These deposits were removed each time to facilitate the removal
of the piston assembly.
A method to easily distinguish between all test runs and to label them
appropriately was developed. Runs were labeled using the following coding system;
# (1-3)
- Letter (A, B, C)
Ring Pack
Speed
- # (1-3)
- Letter (A, B, C)
# (1-5)
Load
Intake Pressure
Run #
I- Standard
A - 1200 RPM
I - 5 Nm
A - Standard Press.
I - Run #1
2-50% OC ring
B - 2400 RPM
2 - 10 Nm
B - 0 kPa
2 - Run #2
3-Invert Scraper
C
3200 RPM
3 - 15 Nm
C - 80 kPa
3 - Run #3
-
For example; 2B IA3 - represents a run with a 50% oil control ring tension, at 2400 RPM
with a 5 Nm load, at Standard atmospheric pressure, and it is the third run at this
operating condition. A similar system was put in place to monitor transient tests. It is as
follows;
Speed Transients;
R
# (1-3)
Ltr (A, B, C)
Ltr (A, B, C)
# (1-3)
Ltr (A, B, C)
# (1-5)
Type
Ring
Initial Speed
Final Speed
Load
Intake Press.
Run #
Pack
Example; RlBC2A2 - Speed Transient, Standard Ring Pack, 2400 RPM * 3200 RPM,
10 Nm Load, Atmospheric Pressure, Run #2.
32
Load Transients;
Example; L1B21A4 - Load Transient, Standard Ring Pack, 2400 RPM, 10 Nm zz 5 Nm
Load, Atmospheric Pressure, Run #4.
This system allowed for easy labeling and retrieval of computer files and general
organization.
3.2 Testing Procedure for the Standard Ring Pack
3.21 Test Matrix 1
Table 3-2 shows the details of Matrix 1.
Name
Speed (RPM)
Load (Nm/bmep)
# of Tests
1A1A(1-4)
1200
LOW(5 Nm/1.4 bar)
4
1A2A(1-4)
1A3A(1)
1B1A(1-5)
1B2A(1-4)
1B3A(1-2)
1C1A(1-4)
1C2A(1-4)
1200
1200
2400
2400
2400
3200
3200
MED(10 Nm/2.8 bar)
HIGH(15 Nm/4.2 bar)
LOW(5 Nmrn/1.4bar)
MED(10 Nm/2.8 bar)
HIGH(15 Nm/4.2 bar)
LOW(5 Nm/1.4 bar)
MED(10 Nm/2.8 bar)
4
1
5
4
2
4
4
1C3A(1-4)
3200
HIGH(15 Nm/4.2 bar)
4
Table 3-2
This matrix includes three speeds and three loads. Initially, four runs were
planned for each condition. The high load condition was completed only once at low
speed and twice at medium speed due to the accumulation of particulates in the sample
line. With the back pressure remaining steady the bypass flow decreased by over 0.5
33
I/min over a period of 2-5 minutes. A decrease in bypass flow causes the calibration data
to be inaccurate for the test condition. An increase in back pressure would increase the
bypass but would alter the operating condition of the engine. This was decided to be a
problem to the system and not correctable at the time of testing. No further runs were
completed at high load. The medium speed-low load condition was previously noted to
have variability by Schofield [9]. For this reason an additional run was conducted at that
speed and load.
3.22 Procedure
The engine was received and was immediately run for 50 hours to break in the oil.
This was to ensure that the oil volatility and viscosity levels were at a steady state level
and that the "high-end" sulfur compounds were released (Flaherty [5]).
Once the engine was broken in, testing commenced. Tests were run in random
order to best ensure repeatability. A typical test day was started with the purging and
calibration of the SO2 diagnostic. This consists of purging the system with "Zero Air"
which is compressed air that all sulfur compounds have been filtered out. This occurs
while the system is allowed to reach its operating temperature. While this is occurring the
engine is warmed and prepared for operation. The gas cart, which consists of a Carbon
Dioxide, Carbon Monoxide, Nitrogen Oxide, Nitrogen Dioxide, and Oxygen analyzers,
was purged with Nitrogen and then calibrated. These were used to monitor gaseous
emissions for calculation of oil consumption and comparison with the ENERAC 2000
(see Miller [21]).
After zero air purging and warm up a known concentration
of SO 2 was introduced
to the system. This "span" gas was allowed to flow for a minimum of 6 minutes to allow
for complete settling of the system. Once this was done the span pot on the front of the
detector and/or the photomultiplier setting within the detector housing were set so the
readout was identical to the concentration of the span gas. During this time, the linear
chart recorder setting and the voltage output to the computer were logged on a data sheet
34
and a computer file respectively. An example of the data sheets is located in Figures A- 1
through A-3 in Appendix A.
The system was then again purged using zero air for a minimum of six minutes or
until the detector again settled on zero ( 0.005 ppm). While the system was being
calibrated the engine was being warmed at 3200 RPM and 4.2 bar bmep (15 Nm). This
was done to ensure that the exhaust system and combustion chamber were heated to a
point where any residual oil particles were vaporized in the system and the surrounding
metal was heated such that no oil particles could condense.
Once the SO2 system was "zeroed" again the system was checked for 03
production. A 5000 ppm NO gas was introduced to the system and allowed to flow for
approximately six minutes. Once the system was settled out, the
03
was secured. The
detector output was monitored for a "spike". Once the detector began spiking, the 03 was
re-energized. The detector was then allowed to zero again. The NO was disconnected.
Span gas was again introduced to the system. This was to check the calibration and was
again monitored by chart recorder and computer. The span gas was secured and the
system was purged with zero air. Once the system was purged the exhaust gas solenoid
valve was opened and the "gasses" valve was secured (see Fig 2-3). This allowed the
engine exhaust gases to enter the system. With the exhaust gases valve open the exhaust
back pressure valve was regulated to ensure proper bypass flow. In this case it was set at
1.5 /min. The system was allowed to settle out for approximately 45 minutes to an hour.
Once the system settled at a test condition, data was taken.
For Matrices 1, l a, 2 and 3 testing consisted of runs of 40 minutes of data
acquisition. Once a run began, SO 2 concentration, RPM, Load, Fuel Flow, Air Flow, and
CO 2 were monitored for the entire time. Miller took two particulate samples per run. The
particulate samples ranged from 5-20 minutes apiece (see Miller [21]). Manual
monitoring occurred of all other parameters of the engine and SO2 diagnostic.
35
A typical time table was as shown in Table 3-3.
Time
o0min
Events
-Computer Acquisition started monitoring SO2, RPM, Load, Fuel Flow, Air
Flow and CO 2 concentration.
- Manual recording started of C0 2 , CO, NO and NO,, via Gas Cart and
5 min
10 min
15-20 rin
20 min
ENERAC 2000 (every 3 minutes)
-Particulate Sample #1 commenced
-Pre-Test operating parameters recorded manually
-Particulate Sample #1 completed
-Engine operating parameters recorded
-Particulate Sample #2 commenced
30-35 min
40 min
-Particulate Sample #2 completed
Test Ende d
Table 3-3
At the completion of a days testing the engine solenoid valve was secured and the
"gases" valve (see Fig 2-3) was opened. This allowed zero air to flow through the system
and to allow a thorough purging of the diagnostic. Once the detector again reached zero,
span gas was introduced to the system and the detector was again calibrated to check for
drift in the detector. Any drift was taken into account with a linear interpolation of the
morning and evening calibrations in the calculation for oil consumption.
The temperatures in the engine very often took up to an hour to reach steady state,
especially the oil temperature. The temperatures had to be monitored carefully to
duplicate previous operating conditions. The oil consumption was calculated from data
collected in the first 10 minutes of testing. This required that the engine was at steady
state prior to commencing testing. The data was collected at a sampling frequency of 0.2
Hz or a point every five seconds. Once all data was collected at the 40 minute mark a new
operating condition was set and the procedure was repeated for the entire matrix.
36
3.23 Matrix 1 - Engine Specifics, Controls and Variables
During the testing the engine was run with an ultra low sulfur diesel fuel so that it
would not contribute significantly to the overall sulfur dioxide concentration. Table 3-4
shows a summary of the diesel fuel characteristics.
API GRAVITY
39.8
FLASH POINT(°C)
68.9
POUR POINT(°C)
-20.6
CLOUD POINT(°C)
-23.3
VISCOSITY (Cs @ 40°C)
2.7
SULFUR(weight ppm)
0.1
HYDROGEN-CARBON RATIO
1.88
HEAT OF COMBUSTION (MJ/kg)
43.1
PARTICULATE MATTER (mg/l)
5.06
CETANE INDEX
55
CETANE NUMBER
42
Table 3-4
The lubricating oil was, as previously stated, Lubrizol 30W with a sulfur content
of 1.27% by weight.
The ring pack configuration for test Matrix
manufacturer's
was the standard as set by
specifications. The first ring or compression ring was chrome plated and
slightly rounded in shape. The second ring or scraper ring was beveled. The third ring or
oil control ring was chrome plated with two rails and a separate coil spring for tension
control.
37
Table 3-5 shows the manufacturer's
specifications.
Ring
Diameter (mm)
Cold Gap (mm)
Tension (N)
Compression
80.25
0.43
9.3
Scraper
80.25
0.43
8.2
Oil Control
80.25
0.51
53.8
Table 3-5 - Standard Ring-Pack Characteristics
The operating conditions for all runs were matched as closely as possible. During
runs initial settings were made versus speed and load. Once these were set the exhaust
temperatures and fuel flow rate were targeted. The following table shows the speed, target
load, fuel flow rate, injection timing and exhaust temperatures.
Speed
Engine Load
(RPM)
BMEP/Torque
Fuel Flow
Injection
Exhaust
(bar/Nm)
Rate
Ti.ning
Temperature
(cc/min)
(°BTDC)
(°C)
1200
LOW
1.4 / 5
8.0
9
240
1200
MED
2.8/ 10
10.9
9
321
1200
HIGH
4.2/ 15
14.0
9
395
2400
LOW
1.4 /5
16.4
14
300
2400
MED
2.8 / 10
22.0
14
365
2400
HIGH
4.2 / 15
29.0
14
475
3200
LOW
1.4 / 5
26.0
15.5
415
3200
MED
2.8 / 10
33.5
15.5
480
3200
HIGH
4.2 / 15
41.1
15.5
545
Table 3-6 - Matrix 1 Variable Specifics
38
3.3 Testing Procedure Matrix la - Standard Ring Pack with altered Intake Pressure
3.31 Test Matrix la
Matrix 1a utilized the same setup as Matrix
with the single exception that the
intake manifold pressures were altered. The matrix was setup as shown in Table 3-7.
Name
Speed
Load
Intake Pressure
# of Tests
(bmep/Nm)
lAlB
IAIC
1A 1C
I20
1200
1.4 / 5
90 kPa
4
1200
1.4 / 5
80 kPa
4
Table 3-7
3.32 Procedure
The calibration of the SO2 diagnostic was completed as outlined in section 3.22.
The engine was adjusted to the 1200 RPM-5 Nm load and allowed to steady out. Once
steady, the throttle valve which was installed in the intake of the engine was slowly
closed while the intake pressure was monitored. When the intake pressure reached the
desired value the engine load was re-adjusted to the proper level, if necessary. The intake
was again monitored and adjusted as necessary. The throttle valve has only a "coarse"
adjustment and a great deal of manipulation was necessary to reach the desired level. The
engine was then allowed to settle out. Engine parameters were monitored to ensure
steady state operation. These runs were intermixed with those of matrix 1 and the
procedure was identical to that which was outlined in section 3.22.
39
3.33 Matrix la Engine Specifics, Controls, and Variables
All of the engine specifics, controls, and variables were the same as in Matrix 1
with the exception of the air intake manifold pressure.
3.4 Testing Procedure for Matrix 2
3.41 Test Matrix 2
Table 3-8 shows the details of Matrix 2.
Name
Speed
Load
# of Tests
2A I A(I -4)
2A2A(I1-4)
2B 1A( 1-4)
2B2A(0)
(RPM)
1200
1200
2400
2400
(Nm/bmep)
LOW(5 Nm/1l.4 bar)
MED(10 Nm/2.8 bar)
LOW(5 Nrn/ 1.4 bar)
MED(10 Nm/2.8 bar)
4
4
4
0
Table 3-8
3.42 Procedure
The engine was dismantled following the completion of Matrix 1, a, R and L.
The head and piston assembly were removed. A new ring pack which had been modified
by Dana Perfect Circle was inserted. The same standard top and scraper ring which were
used in previous testing were again used for the top two rings. The only difference was a
lesser tension oil control ring. The tension was reduced to 28.0 N from an original tension
of 53.8 N. This is a reduction to 52. 1% ring tension. The piston assembly and head were
re-installed. The engine was checked and run to monitor for leaks.
The calibration and preparation of the SO2 diagnostic was the same for the tests of
Matrix 2 as was outlined in section 3.22. The engine was started and procedure was as
40
before. The measurement of the oil consumption for these tests was above the range of
the detector (> 2 ppm SO2 concentration). The test procedure was modified slightly for
these tests. After calibration and system purging of the SO2 detector the engine solenoid
valve was opened, but the gases solenoid was not closed. This allowed a flow of zero air
to flow into the system. The exhaust gases and zero air were mixed thus diluting the
sample to the detector. The amount of zero air injected into the system was monitor:d
manually using the Tylan flow meters associated with the syste.n. A typical run's timeline
would appear as described in Table 3-9.
Time
0 min
Events
-Computer Acquisition started monitoring SO 2, RPM, Load, Fuel Flow, Air
Flow and CO2 concentration.
- Manual recording started of CO2 , CO, NO and NOx via Gas Cart and
ENERAC 2000, and zero air flow recorded.
5 min
10 min
15-20 min
20 min
-Particulate Sample #1 commenced
-Pre-Test operating parameters recorded manually
-Zero air flow altered and recorded
-Particulate Sample #1 completed
-Engine operating parameters recorded
-Particulate Sample #2 commenced
30-35 min
40 min
-Zero air flow altered and recorded
-Particulate Sample #2 completed
-Zero air flow altered and recorded
Test Ended_
Table 3-9
No data was recovered for test 2B2A. The dilution ratio became excessive and the
signal became erratic. (See Chapter 5)
Several levels of dilution were used in an attempt to better calibrate the dilution
ratios. With multiple concentrations and flow rates of dilution gases results were
accurately obtained.
41
3.43 Matrix 2 Engine Specifics, Controls, and Variables
All of the engine specifics, controls and variables were the same as Matrix 1 with
the exception of the ring-pack oil control ring tension. A new oil control ring was
installed with a lower tension as shown in Table 3-10.
Ring
Diameter (mm)
Cold Gap (mm)
Tension (N)
Oil Control
80.25
0.51
28.01
Table 3-10 Modified Oil Control Ring Characteristics
3.5 Testing Procedure for Matrix 3
3.51 Matrix 3
Table 3-11 shows the details of Matrix 3.
Name
3AlA(1-4)
3A2A(1-4)
3B 1A(1-4)
3B2A(1-4)
Speed (RPM)
1200
1200
2400
2400
Load (Nm/bmep)
LOW(5 Nm/1l.4 bar)
MED(10 Nm/2.8 bar)
LOW(5 Nm/1.4 bar)
MED(1lONm/2.8 bar)
# of Tests
4
4
4
4
Table 3-11
3.52 Procedure
The engine was dismantled following the completion of Matrix 2. The head and
piston assembly were removed. A new ring pack configuration was inserted. The same
standard top ring was used, but the scraper ring was re-installed inverted. The purpose of
the inverted scraper ring was to increase oil consumption. The scraper ring is shaped to
42
"scrape" oil downward off the cylinder walls towards the sump. Inverted it scrapes
upwards towards the combustion chamber. Increased oil consumption was desired for the
purpose of obtaining particulate samples at higher oil consumption rates. (See Miller
[21]) The oil control ring which had been used for Matrices 1, a, R and L was also
installed in place of the reduced tension ring. The piston assembly and head were reinstalled. The engine was checked and run to monitor for leaks.
The calibration for the tests of Matrix 3 was the same as was outlined in section
3.22. The engine was started and the procedure was as before except that the oil
consumption for these tests was above the range of the detector (> 2 ppm) as with Matrix
2. The test procedure was also modified slightly for these tests. After calibration and
system purging of the SO2 detector the engine solenoid valve was opened. The exhaust
gases and zero air were mixed thus diluting the sample to the detector. A typical run's
timeline was as described in Table 3-9.
3.53 Matrix 3 Engine Specifics, Controls, and Variables
All of the engine specifics, controls and variables were the same as Matrix 1 with
the exception of the inverted scraper ring.
3.6 Testing Procedure for Matrix R
Matrix R is a study of the transient behavior for changes in speed of ±+25%.
Previous studies have shown that following a speed change oil consumption tends to
"spike" prior to reaching steady state. [7] This phenomena was also observed during the
alteration of operating condition on the Ricardo diesel engine. The purpose of this matrix
is to assess what effects the speed transients have on the oil consumption of the engine.
43
3.61 Matrix R
Table 3-12 shows Matrix R.
Initial Speed
Final Speed
Load
(RPM)
(RPM)
(bmep/Nm)
RIBC1A
2400
3200
1.4 / 5
RIBC2A
2400
3200
R1CB 1A
3200
2400
R1CB2A
3200
2400
Name
# of Runs
2.8/10
1.4/ 5
2.8
10
4
4
4
4
Table 3-12
3.62 Procedure
The speed transients were run singularly without particulate testing. The SO2
system was calibrated as before. The engine was allowed to reach steady state at the
initial operating condition. The data acquisition system was started and all engine
operating parameters were recorded in the initial phase. The engine speed was then
adjusted to the final operating condition as quickly as possible. For speed increases, the
engine took anywhere from 8-12 seconds to reach the final speed. For speed decreases the
speed adjusted more readily(4-5 seconds). This was due to the fact that the dynamometer
increased the resistive torque on the engine to slow it down quickly. On speed increases it
did not apply any negative loads. Simultaneously the engine timing and fuel flow were
adjusted. The SO2 system was monitored to ensure that the bypass flow was within
parameters and corrections were made by adjusting the exhaust back pressure valve (#1
on Fig 2-3). A typical transient run was as described in Table 3-13.
44
Time
0 min
3 min
15 min
Events
-Computer Acquisition started monitoring SO 2, RPM, Load, Fuel Flow,
Air Flow and CO2 concentration.
- Manual recording started of CO2, CO, NO and NOx via Gas Cart and
ENERAC 2000, and zero air flow recorded.
-Adjusted Speed, Fuel Flow, and Timing to new operating condition
-Adjusted exhaust back pressure valve to ensure bypass flow
-Recorded final engine operating parameters
-Ended test
Table 3-13
3.7 Testing Procedure for Matrix L
3.71 Matrix L
Table 3-14 shows Matrix L.
Name
Speed
Initial Load
Final Load
(RPM)
(bmep/Nm)
(bmep/Nm)
L1B1l2A
2400
1.4 / 5
2.8 /10
4
L1B21A
2400
1.4/5
4
L1C12A
3200
1.4/5
2.8/ 10
4
LlC21A
3200
2.79/10
1.4/5
4
2.79/
10
# of Runs
Table 3-14
3.72 Procedure
The load transients were run without particulate testing. The SO 2 system was
calibrated as before. The engine was allowed to reach steady state. The data acquisition
system was started and all engine operating parameters were recorded in the initial phase.
The engine load was then adjusted, using the fuel control servo, to the final operating
45
condition. Simultaneously the engine timing was adjusted. The SO 2 system was
monitored to ensure that the bypass flow was within parameters and corrections were
made by adjusting the exhaust back pressure valve (#1 on Fig 2-3). A typical transient run
is as described in Table 3-15.
Time
0 min
3 min
15 min
Events
-Computer Acquisition started monitoring SO2 , RPM, Load, Fuel Flow,
Air Flow and CO 2 concentration.
- Manual recording started of CO 2, CO, NO and NOx via Gas Cart and
ENERAC 2000, and zero air flow recorded.
-Adjusted Speed, Fuel Flow, and Timing to new operating condition
-Adusted exhaust back ressure valve to ensure bypass flow
-Recorded final engine operating parameters
-Ended test
Table 3-15
46
Chapter 4 TEST CALCULATIONS
4.1 Determination of Engine Oil Consumption.
The sample exhaust gas is taken by the analyzer and delivers an output of the
sulfur dioxide volumetric concentration. This section will describe how to convert the
sulfur dioxide concentrations into useable oil consumption results.
The total weight of water in the exhaust, (H2O)exhaust and the SO2 mass flow rate,
(Sexhaust)
are the two primary values required to calculate the engine oil consumption for
each testing condition. The determination of (H2O)exhaust is necessary for the calculation
of
Sexhaust.
As shown in equation 4-1, the weight of the water in air,
determined from the (H2)weight
fraction, air
(H2
0
)weight-air,
is
mass flow rate and the exhaust mass flow rate.
Tile (H2 0 )weight fractionis calculated using a psychrometric chart given the relative
humidity, air pressure and the air temperature. The air mass flow rate is recorded during
each testing condition and averaged over the course of the test sequence. Exhaust mass
flow rate is calculated as shown below in equation 4-1.
(4-1)
Qexhaust=
Qair
1000
( Vfuel )(P fuel )
(60) 106
where;
Qexhaust =
Mass flow rate of exhaust (kg/sec).
Qair
=
Mass flow rate of air (g/sec).
Vfuel
=
Volumetric fuel flow rate (cm3 /min).
Pfuel
=
Fuel density (kg/m3 ).
47
Computation of (H20)weight-air follows using equation 4-2.
(4-2)
(H 2 ) weight-air
(H2 ) weighraction Qair
Qexhaus)
where;
(H20)weight-air
= Weight of water in exhaust due to ambient air.
(H20)weight fraction
= Weight fraction of water in ambient air.
The molar concentration of water in the exhaust (H 2 0)combustion-molarand the
molecular weight of the exhaust (MWexhaust) are calculated to determine the mass
concentration of water in the exhaust due to combustion
(H 2 0)combustion-molar
(4-3)
(H20)combustion-weight-
is calculated using equation 4-3 given by Heywood [1 ].
(H
2
(C02)o
ol
(CO)tool
°) combmol = 0 5 y (CO) + (CO)m
3.8((CO
2
)mol )
where;
(H2O)combmol
= water in exhaust due to combustion (% molar).
(C0 2 )mol
= carbon dioxide concentration in exhaust (% molar).
(CO)mol
= carbon monoxide concentration in exhaust (% molar).
y
= relative hydrogen to carbon ratio.
The calculation for MWexhaustrequires the air to fuel ratio (). For this Heywood's
equation 3.9 [11] is utilized as shown in equation 4-4.
(4-4)
A
(A / F)actual
(A / F) srtoiciometric
48
Stoichiometric air to fuel ratio depends only on the hydrogen to carbon ratio, y, of the fuel
[11]. Heywood lists equation 4-5 for the stoichiometric air to fuel ratio.
34_56(4
+008
y) y
(A / F)soiciomric= 12.011
+ 1.
(45)
X can be directly calculated using equation 4-6.
(4-6)
=(12.011+
1.008y)Qair
34
(138.24+ 5 6 y)Qfji
where;
X
= air to fuel ratio.
QaJir = Mass flow rate of air (kg/s).
Qfuel
= Mass flow rate of fuel (kg/s).
The equation for the MWexhaust is derived using the formula for stoichiometric
combustion found as equation 3.5 in Heywood [11].
(4-7)
C
b
b
b
Hb + (a + T)(O2 + 3.773N2 ) = aCO2 + H2 0 +3.773(a+ T)N22
The air reactant term in the product is scaled by X as is the oxygen term. From this,
Equation (4-8) is derived. It was used by Laurence [1] and Schofield [9] and was re-
derived for this analysis.
49
32(A(a +
(4-8)
MWexhaust
a +
-)
-)
-))
- -)-))-)
b
4
b
2
- (a +
+ (,(a
b
4
+
b
b
2
4
+ 44.01 la + 18 - + 106.25A(a +
b
4
- (a +
b
4
+ 3.773A(a +
b
4
where;
a
= number of Carbon atoms in a fuel molecule.
b
= number of Hydrogen atoms in a fuel molecule.
X
= airto fuel ratio.
N2
= 28.16 grams/mol
02
= 32 grams/mol.
C
= 12.011 grams/mol.
H2
= 2.016 grams/mol.
A simplified version of (4-8) is shown below as equation 4-9.
a(12.01 1+ 138.25X)+ b(3456a + 1)
(4-9)
MWexhaust
(H20)combustion-weight
a4.773A +b(1.19325A + 0.25)
can now be calculated using the weight of the exhaust by equation 4-
10.
(4-10)
H2 combwt = 18
MC
Uhc,,,"
where;
(H20)combwt
= water in exhaust due to combustion (% by weight)
The total water content of the engine exhaust can now be calculated utilizing 4-1 1.
(4-11)
H2 exhus, = H2 co m bu s t ion-weight + H120 weight-air
50
Now that the total exhaust water content has been calculated, the second step is to
determine the total SO2 flow rate
(Sexhaust)
in the dry exhaust. The calculation of
requires only the calculation of the exhaust mass flow rate
been accomplished. Using equation 4-12, the
(4-12)
Se.rust
f
This has already
can be calculated [Schofield].
Sexhaust
SampleVOllSA
Spanvolts)
(Qexhaust).
Sexhaust
(Qexhaust
)(Spanppm)
2x10
where;
Sexhaust
= sulfur dioxide flow rate (g/hr)
Spanppm
= span gas sulfur dioxide concentration (ppm by weight).
Spanvolts
= output voltage of detector using span gas (volts).
Samplevolts
= sulfur dioxide exhaust flow rate(g/hr).
Qexhaust
= exhaust flow rate (g/hr).
From the sulfur dioxide flow rate, the oil consumption can be found using equation 4-13.
This equation includes corrections for the sulfur content in the fuel and the ambient air
and the water concentration in the exhaust gas stream.
OC = {Sexhaust
- )(1)fuel
[(P 'l )Fu(Air
[
)]
m]
L(Span
_____1)
) ((Pair)(v)air)(Spanppm)
,,, )
(4-13)
where;
Pfuel
= Fuel density (kg/m 3 ).
V fuel
= Volumetric fuel flow rate (cm 3 /min).
Pair
= Air density (kg/m 3).
Vair
= Volumetric air flow rate (cm 3 /min).
Fuelppm
= sulfur content in fuel (ppm by weight)
51
- (H ,
Oe
)
}{ Lubeppm
}
Airv
01 t
= output voltage of detector using cell air (volt)
Lubeppm
= sulfur content of lube oil (% by weight)
OC
= oil consumption of engine (g/hr)
The above equations are used to convert analyzer voltages to oil consumption
values(g/hr). A more appropriate unit of measure is (g/cyl-cycle). To convert use
equation 4-14.
(4-14)
OC(ig / cyl - cycle) =OC(g / hr)(nr)
(RPM)60
where;
N
= Number of cylinders (1 cylinder).
nr
= Number of revolutions per cycle (2 rev/cycle).
RPM = Revolutions per minute (RPM).
52
Chapter 5 RESULTS AND ANALYSIS
5.1 Results of SO2 System Uncertainty Analysis
Following testing, an uncertainty analysis was done on the SO2 diagnostic in an
attempt to determine how much variability and error could be found within the diagnostic
itself. A series of tests were devised to help determine what variables had significant
effects on the apparatus. Not all of the tests were completed due to time constraints, but
Table 5-1 outlines the tests diagrammed and whether they were completed.
Description of Test
Effect of Bypass Flow Rate
Effect of various sample line temperatures
Multiple concentrations of span gas to determine detector accuracy
Interval Testing of span gas to determine detector drift
NO,, effect testing. To ensure proper amount of 03 is injected
Furnace tube diameters. To determine effect of larger tube on systei
Table 5-1
5.11 Effect of Bypass Flow Rate
The system, throughout testing was run at a bypass flow rate of 1.5 - 1.8 /min.
This much flow was believed to be needed so that the analyzer would be fully supplied
with undiluted exhaust gas. As described before, it became apparent that this was actually
not the case and that any positive bypass flow at all would result in the desired, undiluted
sample flow. A test was run to determine whether the amount of flow made a difference
to the analyzer. The analyzer's pyroflourescence detector is supposed to be operated at
atmospheric pressure. Its temperature is self-regulated (The temperature of the detector
was not monitored during testing). A test was run using a 0.90 ppm SO2 concentration
gas at various levels of bypass flow. The detector was calibrated with a bypass flow of 1.5
53
l/min. The computer data acquisition system was set to acquire. The test was commenced
using a bypass flow of 1.0 /min as measured on the floating ball flow meter (bottom of
ball). The flow was regulated by using the Tylan mass flow meter which controlled flow
of gases to the system. This method was chosen over using the needle valve which is
located just prior to the dryer in the diagnostic (see Fig 2-3) in an attempt to match
conditions as closely as possible to actual testing conditions. By closing the needle valve
it would have the system at a different pressure than the analyzer. Although there are no
obvious reasons why this should matter, it was deemed prudent to adjust the flow with the
Tylan mass flow meter. After five minutes, the bypass flow rate was decreased to 0.5
I/min. After another five minutes it was increased to 1.5 /min. The results can be seen on
the graph B- in Appendix B. A summary of results can be seen in Table 5-2.
Bypass Flow
Average SO2
Standard
Coefficient of
(liters/min)
(Volts / PPM)
Deviation
Variation (%)
(Volts)
0.5
4.49 / 0.898
0.025
0.555
1.0
4.72 / 0.944
0.033
0.702
1.5
4.94 / 0.989
0.085
1.718
Table 5-2
These results show that as the bypass flow was increased the concentration of SO 2
also increases. The variability of the analyzers signal also increases with bypass flow rate.
In Fig B- a "hump" is formed when the bypass flow was increased from 0.5 /m to 1.5
I/m. This would indicate a steadying out period is necessary. A possible explanation for
this could be that there is a certain time necessary for the detector pressure to stabilize.
This would also indicate that the pressure of the detector is likely over atmospheric. Since
the signal from the detector changes with the alteration of the bypass flow, and the flow
through the detector is set by a pump-orifice combination, then pressurization of the
sample in the detector must occur.
54
Since only a minimum bypass flow is necessary to maintain an undiluted sample
a bypass flow rate at 0.5 l/min should produce better results. The lower flow rate has two
advantages. It has less variation and is likely to allow the analyzer to operate closer to
atmospheric pressure, and it is also easier to maintain than 1.5 I/m. With the lower flow
rate less back pressure on the engine is necessary. If the back pressure is too great the
performance of the engine is altered. The back pressure of the engine was monitored
using a pressure transducer. During testing, prior to applying any additional back pressure
to the engine, there was, on the average, an exhaust pressure of between 0.03-0.07 bar
over atmospheric depending on engine speed (1200-3200). As the engine speed was
increased the pressure in the exhaust increased. When the back pressure was increased to
produce adequate flow in the S02 diagnostic the exhaust pressure was between 0.07-0.11
bar over atmospheric pressure depending on speed. Again, an increase in speed increased
the back pressure.
All of the test runs in this study were conducted at a bypass flow of at least 1.5
1/min. It has been shown that this was not the bypass flow rate which would produce the
least variant results, but the results, on the average, should be equivalent. The detector
was calibrated daily using the same flow rate with the calibration gas as the flow rate that
the engine produced. This would result in the same conditions for both calibration and the
tests and would ensure reliable results. However, it follows that the results of the oil
consumption tests could vary by 1.7% during operation, due to the variation found caused
by the higher bypass flow rate.
The exces-sivebypass flow did not seriously effect the results of this study. The
engine conditions were modified slightly due to the back pressure on the engine, but this
effect was minimal. Since the calibration of the SO2 system was completed at the higher
bypass flow rates the oil consumption results are accurate. The oil consumption results
contain a slightly higher variability than results which could be obtained at lower bypass
flow rates.
55
5.12 Effect of Various Sample Line Temperatures
A primary focus of this study was to assess the variability of the oil consumption
of the Ricardo Hydra diesel engine at various speeds and loads. It was hypothesized that
part of this variability was caused by the sample line temperature being too low. Previous
tests showed that periodically random "jumps" and "spikes" occurred during operation. It
was important to find out what effect an increase in sample line temperature had on the
apparatus. Therefore, a test was conducted to assess this fact. Standard calibration
procedure was conducted. The engine was allowed to warm and settle out as was
described in section 3.22. The only difference was that the sample line temperature was
reduced from the standard 950°F to 600°F. The engine was run for one hour at 2000 RPM
and 5 Nm with the sample line and "valve line" (see Fig 2-3) at 600°F. The results are
shown on graph B-2 in Appendix B. As can be seen on Fig B-2, the data was "smooth"
for the first 20-25 minutes and then takes a plateau downward for approximately 7.5
minutes and then the signal becomes quite "spikey". Note that the "smooth" signal is still
riddled with "bumps". This signal was not typical of a low load signal found in the steady
state testing which will be discussed later. The speed 2000 RPM's was chosen as an
intermediate speed between medium and low speeds. Unfortunately, after running the
engine for 4 hours it became apparent that at this speed the SO2 signal was not going to
become smooth, even when the temperatures of the sample line and valve line were
increased to 950°F. When the temperature of the sample line and the valve line were
increased to 950°F the signal was no longer "spikey" and it did not contain any plateaus,
but it was not smooth. The importance of this test was to achieve a difference between the
two conditions of sample line temperature. Although neither of the two are "smooth" the
950°F sample line run was much smoother and contained no spikes. (See graph B-3 in
Appendix B). Table 5-3 illustrates the results.
56
Line Temperature
Average SO2
Standard
Coefficient of
(° F)
(Volts / PPM)
Deviation
Variation (%)
(Volts)
600
4.25 / 0.851
0.40
9.34
950
4.649 / 0.930
0.21
4.43
Table 5-3
The table shows that the signal at 600°F has almost twice the standard deviation
with the coefficient of variation being 9.3% compared to 4.4% for the hotter lines. This
doesn't allow for any speculation as to the uncertainty of the results, but it does show that
the 950°F lines have less variability than the colder lines. Since, the results rely on the
engine's performance the actual average SO2 measurement can not be utilized as any
measure. The sample runs were conducted over 3 hours apart. No operating condition
changes were noted. After the completion of data acquisition the engine speed was
decreased to 1600 RPM. The signal became smooth and the bumps noted at 2000 RPM
were no longer evident. A similar test was run increasing the speed to 2400 RPM and
again the bumps were not present. All other operating parameters were the same.
5.13 Electronic Drift of Detector Output
Another concern with the system was that after running the system for multiple
hours the detector's signal would "drift". For this reason a check for repeatability of
signal was done using a known span gas. The system was calibrated as described in
section 3.22. Once calibrated the system was purged with zero air. A known span gas was
introduced. Using the data acquisition system the span levels were recorded after it had
"settled out". The system was again purged with zero air. This procedure was repeated 15
times in 5 set intervals. It took between two and three hours to complete each set of tests.
Table 5-4 shows a summary of results for series #1. Graphical results can be seen in
graph B-4 in Appendix B.
57
Average
Standard
Coefficient of
(Volts)
Deviation
Variation (%)
1
4.635742
0.034766
0.749957
2
4.658317
0.057447
1.233208
3
4.744059
0.039356
0.829591
4
4.72959
0.038253
0.808792
5
4.810612
0.040989
0.852059
Overall
4.715664
0.070163
1.487876
Run #
Table 5-4
Table 5-5 shows the results of series #2. Graphical representation can be found in graph
B-5 in Appendix B.
Average
Standard
Coefficient of
(Volts)
Deviation
Variation (%)
1
4.516276
0.039855
0.882481
2
4.603695
0.057402
1.246878
3
4.725146
0.053317
1.12836
4
4.89637
0.046812
0.956059
5
5.252799
0.10056
1.914411
Overall
4.798857
0.291095
6.065932
Run #
Table 5-5
Table 5-6 shows the results of series #3. Graphical representation can be found in
graph B-6 in Appendix B.
58
Run #
Average
Standard
Coefficient of
(Volts)
Deviation
Variation (%)
1
4.535368
0.031992
0.705391
2
4.526383
0.052807
1.166641
3
4.575651
0.060496
1.322135
4
4.651351
0.042743
0.918944
5
4.662614
0.04529
0.97135
Overall
4.590273
0.063785
1.389563
Table 5-6
The overall differences in average and Coefficient of Variation range from 1.4% 6.1%. This could give an error of up to the maximum of 6.1% for any given run. Due to
time constraints these tests were not done for longer than three hours. Some of this error
was removed during calculation of oil consumption. The system was calibrated in the
morning and the evening. The actual detector span voltages were linearly interpolated
between the morning and evening calibration values.
The detector showed up to 6.1 % drift over the testing period. The testing periods
for these tests were less than three hours. Some testing days, where oil consumption
measurements were taken, were up to ten hours. A calibration curve consisting of a linear
interpolation from morning to evening, from oil consumption results, has proved
adequate. However, it may be advantageous to calibrate at a regular interval during
testing (every 2 hours).
5.14 Partially Completed Tests
There were two tests which were not completed. The test using two span gases
was not completed due to the lack of a second span gas. It was ordered, but was not
59
received until after the apparatus had been dismantled and turned over to another student.
The test analyzing the two furnace tube diameters would be a delicate and time
consuming task. Due to time constraints it was not accomplished. The following is an
outline of recommended study in this area. As previously noted the furnace tube's
diameter was increased due to a perceived problem of the sample gas not reaching a high
enough temperature in the furnace. When the system was first received a one inch
diameter tube was installed. The tube was tightly packed with rock quartz particles. The
temperatures at the outlet side of the furnace during calibration were on the order of
380°F. When that tube was broken, it was replaced with a tube which was filled with a
quartz glass. It was not tightly packed and the particles were of a larger size than the rock
quartz. It was noted that the outlet temperature of the furnace was on the order of 200°F.
At that time it was believed that the gas was not being heated sufficiently in the furnace.
This could have been due to the stay time in the furnace (solution: increase tube diameter)
or due to the now reduced contact surface area in the tube (solution: have tubes packed
tighter). Two inch diameter tubes were purchased and then installed in the furnace.
During calibration the outlet temperature of the furnace was again on the order of 380°F
and the amount of particulate matter found in the filter (see Fig 2-3) was decreased.
Recommended study is to specifically monitor the temperatures of the gas in the SO 2
system with the two inch tube, the one inch tube with quartz glass filling, and the one
inch tube with rock quartz filling.
The primary purpose of this section is to assess how much of the variability on the
oil consumption test results is caused by the SO2 diagnostic itself and to what extent did
the alterations in the system change the diagnostic. The results have shown that at higher
flow bypass flow rates as much as 1.7% variation occurs with a known span gas. The
detector drifts as much as 6%. The oil consumption results described in the following
sections shows some variability. Some of this is due to the variation inherent to the
diagnostic. The detector drift is compensated for by using a linear interpolation of the
calibration values for morning and evening. The sample line temperature alteration has a
significant effect on reducing variability in the oil consumption signal, as was seen in the
60
sample line temperature test. The variability of the diagnostic is not excessive. It should
be on the order of 2-3%, based on the fluctuations due to excessive bypass flow and
detector drift. Outlined in Chapter 7 are means to help reduce any inherent variability in
the system or, at a minimum, to monitor all variables to determine its causes.
5.2 Results for the Standard Ring Pack (Matrix 1)
5.21 Matrix 1: Steady State Speed and Load Effects on Oil Consumption
Steady state oil consumption was calculated in accordance with Chapter 4 for all
of Matrix 1. The results for each run are shown in Figure C- 1 in Appendix C. Figure C-2
shows the results in graphical form. Table 5-7 shows a summary of these results.
Condition
Average OC
Sample Standard
Coefficient of
(_(g/cycle-cylinder)
Deviation
Variation (%)
1200-Low
4.444
0.2955
6.6495
1200-Med
8.350
0.8201
9.8215
1200-High
1.772
0
0
2400-Low
12.666
1.1073
8.7426
2400-Med
14.491
0.9789
6.7551
2400-High
10.966
1.3888
12.6648
3200-Low
17.950
0.6726
3.7474
3200-Med
21.504
0.8063
3.7496
3200-High
12.539
0.4781
3.8129
Table 5-7
The above results show no standard deviations or coefficients of variation for the
1200-High condition. This is due to only having one data point at that operating
condition. The data shows good repeatability for all conditions with the exception of the
61
2400 RPM - high ( 15 Nm) load case. The high load case is variable, but only two data
points were taken at that condition. The inability during testing to maintain adequate flow
in the sample system prevented further testing at high load.
The trend as can be seen in Fig C-3 and C-4 in Appendix C is that the oil
consumption in gg/cylinder-cycle
increases to medium load but decreases to high load.
This is the case for all three speeds. The engine's oil consumption, when operated at the
same load, increases with speed. This is similar to trends found by Miyachika [22] and
Jakobs [23].
The oil consumption was plotted versus the data found by Schofield [9] in Figure
C 5 of Appendix C. The values for all comparable speeds and loads were found to be on
the same order of magnitude. For the lower speeds the data seems comparable. However,
as the speed increases no trends are apparent.
5.22 Variability of Matrix 1 During Steady-State Operation
Figures C-6 through C- 14 show graphs of the computer real-time results of each
operating condition over the ten minute testing cycle. For the low speed-high load
condition there is only one curve and for the medium speed-high load condition there are
only two.
All graphs show variability of less than 15%. The cases of medium speed-high
load being the worst case. All others are below 10%. The expected deviation is expected
to be on the order of 6% for any given run, given the variability found during the
uncertainty analysis.
There are no spikes in any of the runs, nor are there any plateaus. Each run is
"relatively" stable within its own run. This is not to say that at various times spikes were
not seen. On several occasions when the engine operating condition was being altered or
62
the engine was settling out spikes were seen. They were not to the degree to which
Schofield [9] reported and their frequency was far less. The higher load runs show the
highest variability and highest propensity to spike. It was also found that when soot
accumulation appeared to be the greatest, high load for the low speed and medium speed,
the system tended to spike more often. These spikes are likely due to sulfur carrying
particles are either lodged in the exhaust system or in the sampling system. When they
become large enough or conditions change they are dislodged forming a spike.
5.3 Results For Various Intake Pressures (Matrix la)
5.31 Matrix la: Steady State Oil Consumption at Reduced Intake Pressures
Figure D-1I in Appendix D shows the steady-state results that were calculated in
accordance with the equations in Chapter 4. Figure D-2 shows a comparison of oil
consumption of the Matrix a conditions and standard ring pack. The trend is a gradual
increase as the intake pressure is decreased. It should be noted that an intake pressure of
less than 80 kPa caused the engine to slowly bog down and die.
The statistics for each run is shown in Table 5-8.
Condition
Average Oil
Standard
Average Run
Coefficient of
Consumption
Deviation
Standard
Variation (%)
(gg/cyl-cycle)
(jtg/cyl-cycle)
Deviation
101.3 kPa
4.444
0.2955
0.1782
6.6495
90 kPa
8.186
0.0636
0.1984
3.1119
80 kPa
11.800
0.1732
0.4983
5.8716
Table 5-8
The oil consumption increases with each decrease in intake pressure and the
average standard deviation, which is calculated by averaging the standard deviations of
63
each of the four runs. The average standard deviation shows that the signal got
progressively worse as the intake pressure was decreased. This would lead us to believe
that more erratic ring behavior may be occurring.
5.32 Results from Gas Flow and Ring-Dynamics Simulation
An analytical study was done using a computer model of Gas Flow written
by Tian Tian [8]. The model utilizes the engine geometry (Piston, rings, and cylinder) and
cylinder pressures to evaluate ring dynamics, land pressures and gas flow through the ring
gaps and ring grooves. The focus was to identify some of the possible reasons for
increased oil consumption with decreased intake pressure.
The results for Gas Flow pressure data and ring lift are shown in Figures D-6
through D-8 in Appendix D. The top graph in each of the figures shows the pressures of
the top land, 2 ndLand and 3 rd Land. The lower graph shows the location of the top and
2 nd
ring in the ring grooves.
Figure D-9 shows the mass flow between the 2 nd and top land. Figure D-10 shows
the mass flow between the 3 rd and
2 nd
land. The total integrated mass flow through the top
ring gap during the intake stroke (+ downward/-upward)
is -0.18, -0.11, and -0.01 mg for
the 80 kPa, 90 kPa and 101 kPa cases, respectively. This indicates that the mass flow is
very small for the 101 kPa case compared to the other two. Although this indicates the
gas flow, it can be assumed that the oil transport is a function of this flow. Therefore,
there is a significant change in the movement of oil from the 2 nd land to the top land at the
lower intake pressures. Similarly the total integrated mass flow through the 2 nd ring gap
during the intake stroke (+ downward/-upward)
is -0.15, -0.06 and 0.05 mg for the 80
kPa, 90 kPa and 101 kPa cases, respectively. This is significant in that the mass flow for
the 101 kPa case is downward, not upward. In this case, during the intake stroke oil is not
likely to be moved through the gap onto the 2 nd land.
64
In Figure D-9 it can be seen that there is a significant negative mass flow during
the expansion and exhaust strokes. The negative mass flow represents a pressure
differential between the 2 nd land and the top land. In all cases oil will be drawn through
the top sing gap due to the negative mass flow on the expansion stroke. As the intake
pressures become less there will be more oil available on the 2 nd land due to the intake
stroke. The total integrated mass flow during the expansion and exhaust strokes is -1.69,
-1.82 and -1.94 mg for the 80 kPa, 90 kPa and 101 kPa cases, respectively. There is a
higher negative mass flow for the 101 kPa case, it is 12.9% greater than the 80 kPa case.
The fact that the 101 kPa case has the largest negative mass flow is not as important as it
would seem, in that it draws oil from the 2 nd land to the top land. The differences in total
flow in this cases is small and the source of oil is below the oil control ring and the
greater of the flows from the 3 rd to 2 nd lands is the 80 kPa case.
In the 101 kPa case there is never a pressure differential to favor the transport of
oil from the
3 rd
land to the
2 nd
land. In the 90 kPa case there is a 0.1 bar pressure
differential during the entire intake stroke. In the 80 kPa case it is similar to the 90 kPa
case except the pressure differential is 0.2 bar. It is likely that more oil will be drawn onto
the 2 nd land progressively as intake pressure is dropped. Since, during expansion, all three
cases have significant negative mass flows, oil will be drawn through the top gap to the
top land where it can be consumed.
5.4 Results For the Reduced Tension Oil Control Ring (Matrix 2)
5.41 Matrix 2: Steady State Speed and Load Effects on Oil Consumption
Figure E-1 in Appendix E shows the steady-state results that were calculated in
accordance with equations in Chapter 4. Figures E-2 and E-3 show the oil consumption
results graphically for each run and then as averages in (g/cyl-cycle),
respectively. Table
5-9 shows the oil consumption results time averaged over the 10 minute testing cycle, for
each of the four tests, their sample standard deviations, and their coefficients of variation.
65
Figures E-4 through E-6 show the actual oil consumption runs for each operating
condition.
Average Oil
Sample Standard
Coefficient of
Consumption
Deviation
Variation (%)
(gg/cyl-cycle)
(gg/cyl-cycle)
1200- Low
40.789
1.0953
2.6854
1200 - Med
86.161
3.0994
3.5972
2400- Low
152.55
4.5388
2.9753
Condition
2400- Med
Table 5-9
The 2400-Medium condition results could not be processed. This series of tests
included the use of dilution gas. There was too much variation for the sample to be used.
The signal produced varied from 1.0 ppm to > 2.0 ppm within a few seconds. The signal
was highly erratic. Figure E-7 is a sample of the signal produced. The signal plateaus at
10 Volts when the reading is greater than 2.0 ppm. The dilution ratio was extremely high
for this run and the failure of the gases to mix properly is the most probable cause for the
erratic signal.
The oil consumption for this particular engine configuration is on the order of ten
times that of the standard ring pack. The coefficients of variation are small, but that is
directly related to the fact that due to time constraints the runs in this test series were run
back to back. The primary purpose of these runs was to get an idea of the oil consumption
with the altered ring pack and to see the effect on particulate emissions (see Miller [21]).
66
5.42 Variability of Matrix 2 During Steady-State Operation
The variability associated with the test runs for Matrix 2 can be attributed to a
variety of sources. The first, and probably largest source, is the "loose" oil control ring.
This particular element of the ring pack usually maintains the highest tension in the pack.
As stated in section 3.23 the tension according to manufacturer's specifications should be
53.8 N. This ring is set at 28.0 N. A reduction of 47.93%.
The second source of variability is the dilution of the gas. The gas entering the
system is at room temperature and is immediately heated to 1000°C and being mixed with
the sample. There is no way to ensure even mixing throughout the sample without
removing any normal engine fluctuations in the sample gas. In the future an alternative
means to measure samples which are off scale would be to "de-tune" the analyzer by
calibrating the gas to a much lower value on the detector's scale. i.e. if a 1.8 ppm span
gas is used, calibrate the gas as if it is a 0.9 ppm gas. This would allow for detection of
levels up to 4 ppm. The detector according to Flaherty [5] is accurate up to around 10
ppm. Although this method is not desired, if it is necessary, can be an effective means to
measure off-scale samples.
5.5 Results For the Inverted Scraper Ring (Matrix 3)
Figure F-1 in Appendix F shows the steady-state results that were calculated in
accordance with equations in Chapter 4. Figures F-2 and F-3 show the oil consumption
results for each run and then as an average in (ptg/cyl-cycle), respectively. Table 5-10
shows the oil consumption results time averaged over the 10 minute testing cycle, for
each of the four tests, their sample standard deviations, and their coefficients of variation.
67
Average Oil
Sample Standard
Coefficient of
Consumption
Deviation
Variation (%)
(pg/cyl-cycle)
(gg/cyl-cycle)
1200 - Low
21.132
0.9872
4.6715
1200 -Med
36.105
2.3211
6.4289
2400 - Low
79.832
3.0761
3.8533
2400- Med
149.89
2.5989
1.7339
Condition
Table 5-10
The oil consumption for this particular engine configuration is on the order of five
times that of the standard ring pack. Again, the coefficients of variation are small, but
that is directly related to the fact that due to time constraints the runs in this test series
were run back to back. The primary purpose of these runs was to get an idea of the oil
consumption with the altered ring pack and to see the effect on particulate emissions (see
Miller [21]). Figures F-8 and F-9 in Appendix F illustrate the different oil consumption's
for the three different ring pack configurations. In general they follow the same trend for
each of the various operating conditions.
In Matrix 2 and Matrix 3 an increase in oil consumption was expected and the
data verified this expectation. These changes were done primarily to increase oil
consumption so that the effects on the particulate emissions could be seen (see Miller
[21]). While no tests were done to see if other changes in geometry of the scrape ring nor
an increased tension oil control ring would decrease oil consumption, this is likely the
case. Quantitatively, it is impossible to estimate possible effects of an increased oil
control ring tension, but the oil consumption is likely to decrease. This is an area for
further exploration to attempt to quantify this assumption.
68
5.6 Results For the Speed Transients
The results of the Speed Transient Tests were converted to oil consumption
measurements. The four different transients measured are as described in Table 3-12. A
copy of table 3-12 is shown below.
Name
Initial Speed
Final Speed
Load
(RPM)
(RPM)
(bmep/Nm)
RlBC1A
2400
3200
1.4/ 5
4
R1BC2A
2400
3200
2.8 /10
4
R1CB1A
3200
2400
1.4/5
4
R1CB2A
3200
2400
2.8 / 10
4
# of Runs
Table 3-12
The case of RlBC1A where the speed was changed from medium speed to high
speed at low load a transient "hump" was found in all four cases. These runs can be seen
in Figures G-1 through G-4. The size of the hump varied with each run. In all four cases
the engine was run for only 15-20 minutes at the low load condition prior to running the
transient. The analysis for the four runs is shown in Table 5-11.
Avg Initial
Avg Final
Avg Change
Hump max
Hump Avg
Time of
Run
OC
OC
in OC
over final
over final
Hump
#
(gg/cyl-cycle)
(g/cyl-cycle)
(g/cyl-cycle)
Avg
Avg
(sec)
(Rg/cyl-cycle) (gg/cyl-cycle)
1
13.97
19.54
5.57
2.48
1.46
39
2
14.83
16.96
2.13
14.20
10.08
378
3
11.21
16.51
5.30
3.08
1.52
33
4
12.20
18.46
6.26
13.52
5.92
45
Table 5-11
69
The runs themselves are similar in that the oil consumption increases on average
by 4.8 gg/cyl-cycle. The increase from the steady state calculations from section 5.31 is
5.2 gg/cyl-cycle. This is even closer if run number two is disregarded. For each of the
runs starting and finishing oil consumption levels are within range of the oil consumption
values found in steady state measurements. Most of the values are within one standard
deviation of the mean, all are within two.
The same trend is found if looking at runs number one, three and four. The
apparent oil consumption rises into a "hump" or spike for approximately 40 seconds and
then decreases to the steady state level. The engine does not take long to reach steady
state due to only a minor increase in exhaust temperature. The exhaust temperature
change is on average only 28°C.
The second run appears to be an anomaly. A thorough examination of the run
itself and its surrounding runs result in no additional information as to the cause of this
"plateau" in oil consumption. It's duration is for over six minutes and it is not a "smooth"
signal even at its heightened level. The oil consumption does not steady out until almost
seven minutes after the initial change in speed. This was the last run on the particular day,
but there does not to appear to be any oddities with the particular run.
The humps found in the oil consumption can actually mean higher engine oil
consumption during the transients, but it is not necessarily the only explanation. The
humps could also be caused by sulfur bearing particles becoming lodged or adhering to
the exhaust line or sampling system during low speed or load condition. These particles
would remain there in a steady state environment unless they "grew". At which time they
would be dislodged and would form a spike. The transients run show very little change in
exhaust temperature, but have a marked increase in exhaust flow. The increased flow
could dislodge these particles and they would be picked up by the sampling system.
70
The transients run in these tests are small. The speed transients are 800 RPM.
There is not likely to be any major ring dynamics attributing to an increase in oil
consumption. However, there is a change in cylinder temperatures which may attribute to
some of these changes. At a lower speed the temperatures of piston, ring and liner are
lower than at higher speeds. When the speed is increased to a position of higher steadystate oil consumption, for a period of time, there will be heightened oil consumption due
to the time lag of the temperatures of the piston, ring and liner. When these components
are "cooler" they will be of a slightly smaller size and will cause clearances to be larger.
As the temperatures increase the clearances between these components decreases. The
approximate thermal time scale can be seen through equation 5-1.
5-1
ThermalTimeScale=
L2
V
where;
L2
=
Length scale (squared)
v
=
Thermal Diffusivity (m2/s)
The thermal diffusivity is equal to;
vpcp
V =k
where;
p
= density (kg/m3 )
cp
= Specific Heat (J/kgK)
k
= Thermal Conductivity (W/mK)
Using the radius of the piston as a primary length scale (3-4 cm) and the
diffusivity of iron (23.1 x
106),
yields a time scale of 39 to 69 seconds. This falls into the
range of the length of the humps found in the speed transients. This may therefore be a
source of oil consumption within the transients.
71
The cases of RlBC2A are shown in Figures G-5 through G-8 in Appendix G.
These runs were again increases in speed from 2400 RPM to 3200 RPM. They were
conducted at 10 Nm load. Although the high speed medium load signals are somewhat
more erratic than those found at the low load condition there appears to be no humps or
plateaus in any of the three runs completed. The results are shown in Table 5-12.
Run #
Avg Initial
Avg Final
Average increase in
OC
OC
Oil Consumption
(gg/cyl-cycle)
(gg/cyl-cycle)
(gg/cyl-cycle)
1
14.87
23.08
5.21
2
12.85
22.72
9.35
3
12.67
23.38
10.71
4
11.88
24.15
12.27
Table 5-12
The average initial and the average final values are all within a standard deviation
of the mean found in section 5.21. The average increase found in the steady state
calculations was 7.92 gg/cyl-cycle (see section 5.21). The signal is somewhat erratic, but
as previously stated shows no humps. This is contradiction to the case at low load. The
difference between the two is the temperature at which the transient took place. The
theory that sulfur bearing compounds are lodged in the exhaust system at lower loads
appears to hold true. The increase in temperature makes the compounds less likely to
remain resident and therefore, no humps during the transients. The exhaust temperature at
low load went from, on average, 270°C to 298°C. The exhaust temperature at medium
load went from, on average, 363°C to 409°C. The temperatures at medium load are
approximately
100°C hotter than at low load. The variation in the signal at high speed and
medium load is similar to that seen for the steady state condition.
72
The case of the R 1CB 1A runs are shown in Figures G-9 through G- 12 in
Appendix G. These transients were conducted starting at 3200 RPM and reducing speed
to 2400 RPM at 5 Nm load. The signals each decrease from start to finish corresponding
to the time of speed change. The first three runs are somewhat different from run four.
The first three show a "negative" hump following alteration of speed. The last shows no
"hump" whatsoever. The analysis for the four runs is shown in Table 5-13.
Avg Initial
Avg Final
Avg Change
Hump Max
Hump Avg
Time of
Ran
OC
OC
in OC
over final
over final
Hump
#
(ggcyl-cycle)
(gg/cyl-cycle)
(gg/cyl-cycle)
Avg
Avg
(sec)
(pg/cyl-cycle)
(gg/cyl-cycle)
1
18.35
13.25
- 5.10
- 1.45
- 0.88
152
2
17.96
14.15
- 3.81
-3.67
- 2.4
131
3
16.50
13.25
- 3.25
- 2.47
- 1.51
135
4
12.20
18.46
N/A
N/A
N/A
N/A
Table 5-13
The humps are of significantly different size and are not of equal areas.
Integrating the humps using Simpson's Rule and converting time into cycles results in
largely differing sizes as can be seen from table 5-14. The fourth and final run was not
analyzed due to its failure to show any form of hump.
Run #
Area in
(jig)
1
14268.7
2
33536.0
3
21744.0
Table 5-14
73
The case of the R 1CB2A runs are shown in Figures G- 13 through G- 17 in
Appendix G. These transients were conducted starting at 3200 RPM and reducing speed
to 2400 RPM at 10 Nm load. The runs of this test series appear non-repeatable. The first
two runs show spikes following the alteration of speed and then a slow decrease in oil
consumption until steady state is reached. Runs three, four and five appear to behave
similarly to the runs found at decreasing speed at 5 Nm. There is a negative hump in all
cases, but the hump doesn't go below final steady state results as was the case of the runs
at 5Nm. These two runs appear to decrease to steady state value and then increase to a
plateau for a period of time and then settle out at steady state. The periods of time at this
plateau are not equivalent (260, 380 and 160 seconds, respectively) nor are the jumps of
similar height (3.6, 6.4 and 2.8 gg/cyl-cycle, respectively). The final run even appears to
have two smaller plateaus with the second, albeit slightly flat, lasting for 190 seconds
with an increase of 2.0 gg/cyl-cycle. The expected results are that the oil consumption
would be opposite of that found with the positive speed transients (from 2400 RPM to
3200 RPM). The oil consumption would be steady and then when the speed was reduced
the oil consumption would reduce. With the average temperature of the exhaust being
higher it would be expected that there wouldn't be any humps. There appears to be no
repeatable trend with any of this series test runs.
With the increase in speed at low load a positive hump was found with the
increase in oil consumption associated with the speed change. With the decrease in speed
a negative hump was formed. The integration of these humps represents the transient oil
consumption in gg of oil. For the increase at low load the average oil consumption per
run was 41817.4 gg of oil. For the decrease in speed at low load the average oil
consumption per run was 23182.6 gg. These values, although different by a factor of
about 2, are of the same order of magnitude. The oil consumption is not "regained" when
the engine speed is reduced again, the oil consumption is reduced for a period of time
prior to reaching steady state. This is an interesting prospect in that it was believed that no
matter what the direction of the transient that oil consumption was increased. (Ariga [7])
74
Additional study should be done to assess better quantitative results about this
phenomena.
5.7 Results For the Load Transients
The results of the Load Transient Tests were converted to oil consumption
measurements. The four different transients measured are as described in Table 3-14. A
copy of table 3-14 is shown below.
Name
Speed
Initial Load
Final Load
(RPM)
(bmep/Nm)
(bmep/Nm)
LIB 12A
2400
1.4/ 5
2.8 /10
4
LlB21A
2400
2.79/ 10
1.4/5
4
LIC12A
3200
1.4 / 5
2.8/ 10
4
LIC21A
3200
2.79/ 10
1.4/ 5
4
# of Runs
Table 3-14
The load transient signals were not converted to oil consumption. The SO2 signal
is proportional to oil consumption. The first series of tests, the LI B 12A, required the
engine to be running at steady-state at 2400 RPM and 5 Nm load. The load was increased
to 10 Nm. The four test runs are graphically shown in Figures H-1 through H-4 in
Appendix H. These runs each show an increase in signal with an increase in load. The
increase in each case is accompanied with a "hump" in the signal. As before with the
speed transients these humps are a sign of increased sulfur output to the analyzer.
The important values associated with these humps are shown in Table 5-15.
75
Run #
Average
"Hump" Max
"Hump"
Duration of
Change in S02
over final
Average over
"Hump"
signal (Volts)
Average
final Average
(sec)
(Volts)
(Volts)
1
0.879
2.676
1.221
343
2
1.161
0.839
0.376
133
3
1.154
0.614
0.195
163
4
1.321
1.185
0.517
190
Table 5-15
The results as shown above are similar in that each run exhibited a hump, but as
can be seen there is very little correlation between them. As before there appears to be an
anomaly with one run. In this case it is run #1 which is away from the norm. The
difference in final SO 2 signal is less than the others and the hump is far and away larger
than the others. However, unlike the previous case when each were run separately and
with only a 15-20 ninute prelude time, this run had been at the low load condition for a
substantial period of time ( > 1 hour). None of the other three runs was run at the low load
condition prior to the testing. This is significant in that the engine/diagnostic
had a long
period of time in which to become saturated with unburned oil particles containing sulfur.
(see Chapter 6). Table 5-16 shows the results of when the humps are integrated as before.
Run #
Area in
(Volt-sec)
8376.1
1
2
.,
3
1000.2
635.7
4
1964.6
Table 5-16
76
The area found under these curves reveals little. The actual time spent at the
medium speed and low load condition prior to initiating the tests is unknown. This may
be a variable which when plotted against these areas would prove meaningful. Future
tests should attempt to monitor this time and attempt to correlate that time with the areas
under the hump.
The L1C12A conditions are graphically shown in Figures H-S through H-8 in
Appendix H. Each of the four runs completed at 3200 RPM altering load from 5 - 10 Nm
shows a small hump or no hump at all. The first two runs show humps. The second two
show variation, but no discernible humps. Analysis of the runs is shown in Table 5-17.
Average
"Hump" Max
"Hump"
Duration of
Change in SO2
over final
Average over
"Hump"
signal (Volts)
Average
final Average
(see)
(Volts)
(Volts)
1.911
1.14
0.457
300
1.046
2.422
0.652
190
3
1.173
N/A
N/A
N/A
4
2.075
N/A
N/A
N/A
Run #
1
2
Table 5-17
The two runs which exhibit no humps show high variability and changing SO 2
concentrations. The first two runs which show humps have more steady SO 2 signals.
However, the runs were completed at the high speed and exhaust flows were on the order
of 50% higher than at 2400 RPM. Also, both runs which showed humps were following
runs of high speed and low load. The engine had been at the low load operating condition
for a minimum of one hour prior to initiation of this test.
77
The L1 B21A conditions are graphically shown in Figures H-9 through H-13 in
Appendix H. Each of the five runs were completed at 2400 RPM altering load from 10 - 5
Nm. All five of these runs look similar. They each decrease with decreasing load. Three
of the five show negative humps. The second and fourth runs show no apparent humps.
The third run has the largest hump. Analysis of the runs is shown in Table 5-18.
Run #
.1
Average
"Hump" min
"Hump"
Duration of
Change in SO2
over final
Average over
"Hump"
signal (Volts)
Average
final Average
(sec)
(Volts)
(Volts)
-0.415
- 0.217
392
- 0.707
-
2
- 1.216
N/A
N/A
N/A
3
-0.57
- 0.332
- 0.204
185
4
- 0.866
N/A
N/A
N/A
- 1.482
- 0.462
- 0.274
96
5
Table 5-18
The humps that exist are small and have little correlation with each other. On
average they differ from the final values by a similar amount, but their durations are
varied. All five runs were proceeded by runs at the B2 condition (2400 RPM - 10 Nm).
The result of integrating the humps can be seen in Table 5-19.
78
Run #
Area in
(Volts-sec)
1
1701.28
2
N/A
3
754.8
4
N/A
5
526.1
Table 5-19
The LlC21A conditions are graphically shown in Figures H-14 through H-17 in
Appendix H. Each of the four runs were completed at 3200 RPM altering load from 10 5 Nm. All four of these runs are similar. They each decrease with decreasing load. None
of the runs show negative humps of any magnitude. Run number two has a very small
negative hump. It's integral results in 85.3 gg. That is an order of magnitude smaller than
the humps previously discussed. Table 5-20 shows a summary of the runs.
Run #
Average increase in SO2 Signal
(Volts)
1
- 1.407
2
- 0.939
3
- 1.194
4
- 1.42
Table 5-20
79
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80
Chapter 6 CONCLUSIONS
Diagnostic Issues
1. The Sample Line temperature should be increased from the previous standard of
600°F to 950°F. The lower temperature sample line produces results which have a
higher variability and have shown in tests to result in spikes. The low sample line
temperature allows particles to become lodged in the line and are released at random
intervals causing results to vary.
2. The bypass flow of the SO 2 Diagnostic should be maintained at 0.5 liters/min vice 1.5
liters/min. The lower flow rate produces much more stable results with less
variability. The lower bypass flow also reduces the exhaust back pressure
requirements.
Steady 'tate Oil Consumption
1. The Real Time Sulfur Dioxide Oil Consumption measurement system described in
this work is a viable means to measure oil consumption. It produces repeatable values
of oil consumption on a single-cylinder diesel engine.
2. The Ricardo Hydra Diesel engine while running at steady state at 1200, 2400 and
3200 RPM produces no time dependent variations in oil consumption level for the
three loads tested (1.4, 2.8, and 4.2 bar BMEP). The overall level of oil consumption
for each operating condition at steady state was stable and showed little variation
between repeated runs. The previously found oil consumption level variations could
not be reproduced.
3. The Oil Consumption of the Ricardo Hydra Diesel engine is a function of speed and
load. As the speed of the engine was increased for any particular load the oil
81
consumption was increased. The oil consumption, with regard to the load of the
engine, is such that it increases with load until mid-load, but decreases at high load.
(83.3% of full).
4.
The oil consumption on the Ricardo Hydra Diesel engine increases with decreasing
air intake manifold pressure. The coefficient of variability shows that each of the three
series of runs show adequate repeatability between the runs. As the intake air pressure
is decreased the pressure differential between the top land and the 2 ndland and the 2 nd
land and the 3 rd land will be greater, causing the oil to have a higher propensity to be
drawn up and through the ring pack.
5. The oil consumption of the Ricardo Hydra Diesel engine with a 52% Tension oil
control ring is increased by an average of 10.5 times "normal". The oil control ring is
a vital control on this engine in limiting the flow of oil through the ring pack. The oil
consumption with an inverted scraper ring shows an increase in oil consumption on
an average of 6.44 times "normal". The engine oil consumption for this study was
increased to develop a relationship between oil consumption and particulate rates (see
Miller[21]). By altering the ring geometry significant increases in oil consumption
were found. Alternate ring geometries should be possible to decrease engine oil
consumption. Decreasing the oil control ring tension increased oil consumption,
conversely increasing the oil control ring tension should decrease oil consumption.
Transient Oil Consumption
1. In transients of increased speed or load positive "humps" of oil consumption can be
seen. There are two sources of this apparent oil consumption. The first is that sulfur
bearing particles are lodged in the exhaust and sampling system and during the
transient are dislodged. This would mean that the measured oil consumption transient
was from oil already consumed by the engine. The second is that the humps are due to
thermal lag, seen through the thermal time scale. The piston, ring and liner react
82
slowly in response to temperature changes within the cylinder. The piston to liner
clearances and ring gaps are temperature dependent. As the speed and load are
increased the steady state oil consumption is increased. The gaps and clearances
remain "wide" for a period of time until the components reach the steady state
temperature.
2. In decreasing transients the negative "humps" were seen in the low load conditions.
These negative "humps" are likely caused by the thermal time lag between piston,
ring and liner, as described above. The integrated areas of the positive and negative
"humps" are of the same order of magnitude in size, but the positive "humps" are
approximately twice the size of the negative "humps". This could be due to the
positive "humps" being caused by a combination of particles dislodging and a thermal
time lag.
83
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84
Chapter 7 RECOMMENDATIONS
1. SO2 Diagnostic
Procedures
1. A "weigh and drain" or another reliable method of measuring oil consumption
should be employed to verify the results gained through the SO 2 system. If the
"weigh and drain" type method were employed it could be done at the end of
every day of testing. At the beginning of the day the oil would be completely
drained from the engine and weighed. The engine would then be refilled with
a known mass of oil. (If it were done daily the oil could be left out from the
night before, re-weighed in the morning and the engine then refilled.) At the
end of the day the oil would again be drained and weighed. Other methods are
available, such as the tritium technique are available, but are not as easily
accomplished.
2. The "cell air" testing method needs to be modified such that cell air can be
more easily tested. It's current configuration does not allow for the cell air to
be monitored. An alternative piping is shown in Figure 7-1. A 3-Way valve is
added in the bypass line. When testing the cell air, two purposes of the valve
could be utilized. The valve could be closed altogether ensuring that the flow
to the analyzer was from the cell, or if the valve is turned such that Bypass is
closed and the other line which links to cell air is opened. This also would
ensure cell air being tested. However, in the second method the air is not
drawn through the entire system like the sample. Another alternative to repiping the bypass is to acquire a second SO2 analyzer which would constantly
monitor SO 2 in the air of the cell (See below).
85
03
Alternate Cel
3
1
Cell Air
From Furna
Figure 7-1
3. Alter the instructions for use which dictate that 1.5 l/m of bypass flow are
required for proper operation of the diagnostic to 0.5 I/rm.These instructions
have been found to be erroneous. The higher bypass flow rate has been found
to be detrimental.
4. A complete uncertainty analysis should be completed;
A. The sample line test should be run again using a more stable speed.
Alternate sample line temperatures should be tested in an attempt to
optimize the sample line temperature.
B. A multiple span gas test should be run. This would verify how well the
detector responds to different concentrations of SO2 .
and
C. The "interval" test should be run at a lower bypass flow (0.5 I/mrn)
for more consecutive iterations (10-15) to see if the signal becomes
less variant due to the bypass flow.
86
D. A larger scale comparison of the S02 gas should be made for various
bypass flow rates (0.1
To best accomplish this a better
mUrn
to 2.5 /mrn).
flow meter should be installed (see below, in EQIPMENT).
E. A test to determine the effect on altering the tube size and filling of the
glass furnace tubes. The diameter was changed in response to lower
furnace exit temperatures and a higher accumulation of soot in the
filters. The alteration of tubes would determine whether this is
necessary, and if it has any effect on the gas itself. Zero Air or
Breathing Air should be run through the system at a typical flow rate.
The sample line and valve line temperatures should be set and
monitored as normal. With each of the three types of tubes, 2 in
diameter,
in diameter glass filled, and 1 in diameter with rock quartz
filled, monitor the furnace exit temperature. If the temperature varies
the gas is not reaching the desired 1000°C temperature in the furnace.
A follow on test to this is to increase the temperature of the furnace. It
is capable of temperatures up to 1400°C. (Caution: It is unknown at
this time what temperature causes the furnace tubes to melt.
Recommend a thorough investigation into the exact temperature of this
occurrence prior to attempting this test.)
Equipment
1. The addition of a small high temperature vacuum pump should be added
following the furnace. It should be located following the furnace (so as not
to disturb the uncornbusted sample) and it should be of the appropriate
capacity and able to withstand high temps (=500 °F). This would eliminate
the problem of back pressure and maintaining a bypass flow.
2.
It is desirable to monitor as many operating parameters as possible. The
current data acquisition system was only capable of monitoring 8 channels
at one time. With seven necessary measurements for the calculation of oil
consumption this leaves only one channel to monitor any of a number of
87
variables. A list of variables that should be monitored on a real time basis
in order of priority is shown in Table 7-1
Essential
Important
Desired
S02 concentration
Engine L/O Temp
Furnace Exit Temp
Engine Speed
Engine Exh Temp
Analyzer Inlet Temp
Engine Load
Cell Air S02 concentration
Intake Manifold Pressure
Engine Fuel Flow
Sample Line Temp
Engine Intake Temp
Engine Air Flow
"Valve Line" Temp
Exhaust CO concentration
Exhaust C02 concentration
Engine Exh. Back Pressure
Bypass Flow Rate
Table 7-1
Most of these were monitored manually, but it was impossible to monitor
them with any degree of frequency such that any definitive conclusions
could be drawn for any erratic behavior.
3. Shorten the heated lines which run from the furnace to the detector. These
lines are on the order of 40 feet and are not needed.
4. Install a second SO2 detector to go along with the cell to monitor cell
sulfur content. The amount of sulfur in the cell could vary on an hourly
basis depending on how many engines are being run in the lab. Else,
monitor cell air after each run utilizing procedure outlined above.
2. Lube Oil Consumption Testing
1. Speed and Load transients of small scale (approximately 50%
increases/decreases) resulted in unpredictable lube oil consumption "humps".
These humps should be explored further by specifically monitoring duration at
certain speeds, accumulation in sample lines, alterations in Bypass flow, and
transient behavior with large scale changes. The transient oil consumption for
88
small cases has been shown is not necessarily due to engine changes. It is, in
this case, most likely due to accumulation of particles in the lines/exhaust
manifold and associated piping. For large scale transients this may not be the
behavior. Attempt to monitor this with the SO2 system in conjunction with
Laser Induced Fluorescence (LIF) to monitor oil film thickness.
2. Testing of alternative ring packs showed large changes in oil consumption due
to inverting the scraper ring and decreasing the tension in the oil control ring
by approximately 50%. Additional ring tests should be attempted using
smaller changes and geometrys to determine changes in oil consumption.
3. Further testing of different intake manifold pressures of greater than
atmospheric pressure should be attempted. This would further the theory that
the oil consumption should increase with decreasing air pressure. It should
therefore, decrease with increased air pressure. The air should be closely
monitored for oil and sulfur content prior to injecting it into the intake lines.
89
(This Page Intentionally Left Blank)
90
REFERENCES
1. Laurence, R. B., "The Effects of Lubrication System and Marine Specific Factors on
Diesel Engine Emissions," Masters Thesis, Departments of Ocean and Mechanical
Engineering, Massachusetts Institute of Technology, 1994
2. Yoshida, H., et. al. "Diesel Engine Oil Consumption Depending on Piston Ring
Motion and Design" SAE Paper 930995.
3. Lusted, M. R., "Direct Observation of Oil Consumption Mechanisms In a Production
Spark Ignition Engine Using Fluorescence Techniques," Masters Thesis, Departments
of Ocean and Mechanical Engineering, Massachusetts Institute of Technology, 1994.
4. Hartman, R. M., "Tritium Method Oil Consumption and Its Relation to Oil Film
Thicknesses In a Production Diesel Engine," Masters Thesis, Departments of Ocean
and Mechanical Engineering, Massachusetts Institute of Technology, 1990.
5. Flaherty, Richard, Cummins Engine Company, 1995.
6. Hill, S. et. al., "A Systems Approach to Oil Consumption" SAE Paper 910743.
7. Ariga, S. et. al., "On-Line Oil Consumption Measurement and Characterization of an
Automotive Gasoline Engine by SO 2 Method," SAE Paper 920652.
8. Tian, T., "Modeling Piston-Ring Dynamics, Blowby, and Ring-Twist Effects" ASME
Paper submitted to ASME - ICE Fall Tech Conferenc, Oct 1996.
9. Schofield, D. M., "Diesel Engine Instantaneous Oil Consumption Measurements
Using the Sulfur Dioxide Tracer Technique," Masters Thesis, Departments of Ocean
and Mechanical Engineering, Massachusetts Institute of Technology, 1995.
10. Ford, E. J., "The Effects of Lubrication System Parameters and Exhaust Aqueous
Injection on Diesel Engine Oil Consumption and Emissions," Masters Thesis,
Departments of Ocean and Mechanical Engineering, Massachusetts Institute of
Technology, 1995.
11. Heywood, J. B., Internal Combustion Engine Fundamentals, McGraw-Hill Book
Company, New York, 1988.
12. Hiruma, M., et al., "Effect of Piston Ring Movement Upon Oil Consumption," JSAE
Review, March 1993.
13. Yoshida, H., et. al. "Diesel Engine Oil Consumption Depending on Piston Ring
Motion Design," SAE 930995.
91
14. Burnett, P.J., et. al., "Characterisation of the Ring Pack Lubricant and Its
Environment," Shell Research Paper.
15. Bailey, B. K., et. al., "On-Line Diesel Engine Oil Consumption Measurement," SAE
902113.
16. Ariga, S., et. al., "Instantaneous Unburned Oil Consumption Measurement in a Diesel
Engine Using SO2 Tracer Technique," SAE 922196.
17. Inoue, T., et. al., "Study of Transient Oil Consumption of Automotive Engine," SAE
892110.
18. Hanaoka, M., et. al., "New Method for Measurement of Engine Oil Consumption (S-
Trace Method)," SAE 790936.
19. Hase, Y., et. al., "Nissan Oil Econometer Permits the Measurement of Engine Oil
Consumption," SAE 810754.
20. Johnson, J. H., et. al., "A Review of Diesel Particulate Control Technology and
Emissions Effects - 1992 Horning Memorial Award Lecture," SAE 940233.
21. Miller, T. C., "Characterization of Lube Oil Derived Diesel Engine Particulate
Emission Rate Versus Lube Oil Consumption," Masters Thesis, Departments of
Ocean and Mechanical Engineering, Massachusetts Institute of Technology, 1996.
22. Miyachika, M., et al., "A Consideration on Piston Speed Land Pressure and Oil
Consumption of Internal Combustion Engine." SAE 840099.
23. Jakobs, R. J., et. al., "Aspects of Influencing Oil Consumption in Diesel Engines for
Low Emissions," SAE 900587.
24. Wong, V. W., et. al., "Assessment of Thin Thermal Barrier Coatings for I.C.
Engines," SAE 950980.
92
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C6
Results: Test Matrix 1
Test
lalal
1ala2
1ala3
1ala4
1a2al
1a2a2
1a2a3
1a2a4
1a3al
1bla
1b1a2
lb1 a3
1b1a4
1bla5
1b2a1
1b2a2
1b2a3
1b2a4
1b3a1
1b3a2
1clal
1cla2
lcla3
1cla4
1c2al
1c2a2
1c2a3
1c2a4
1c3al
1c3a2
1c3a3
1c3a4
CO
C02
(% molar) (% molar)
0.05
4.8
0.025
5.254286
0.05
3.683333
0.025
3.85
1.1
5.7
0.97
6.761429
1
6.875714
1
5.54
3.1
8.2
0.5
5.864
0.05
5.864
0.025
3.64
0.025
3.301111
0.0225
3.17
0.02
5.0025
0.025
6.28
0.025
6.1475
0.05
4.82375
0.13
8.01
0.116
7.95
0.025
4.5
0.025
4.6
0.025
2.9
0.025
3.53625
0.02
4.604
0.035
6.54
0.035
6.62
0.05
4.762222
0.7
8.41
0.72
8.11
0.59
6.5
0.55
6.03
Total
Exh Water
(% by Wt)
4.559773
4.85125
4.318696
4.015237
5.611636
6.863964
6.65178
5.381911
7.544813
5.432942
4.99971
2.13113
3.547254
3.616492
4.911428
5.21987
5.047903
4.914466
6.210547
6.169495
4.097607
4.253466
3.337876
3.534332
4.289789
5.421016
5.467281
5.306242
6.711425
6.54488
6.306635
6.015918
verag Average Average
Avg
Average
Average
Load
Fuel
Air
OC
OC
SOC
(N-m) (cc/min) (mA3/min) (g/hr) (ug/cyl/cyc) (g/kW-hr)
5.29 7.90853 0.258765 0.1552 4.29656576 0.232645
5.5 8.43425 0.261876 0.1713 4.74189987 0.247006
5.48 8.36019 0.262048 0.1483 4.10448693 0.214764
6.23 7.67008 0.231821 0.1668 4.63439888 0.212331
10.7 11.4913 0.259249 0.3434 2.37644014 0.254354
13.4 10.883 0.258511 0.2877 1.99088054 0.219527
10.7 10.8081 0.258546 0.2767 1.91695886 0.205478
11.3 10.9318 0.21069 0.2936 2.03179926 0.20684
15 20.7068 0.256345 0.0638 0.44296958 0.033881
5.39 16.6532 0.494911 0.9546 3.30856013 0.702771
5.35 16.6248 0.488851 1.0316 3.57705461 0.765703
5.45 15.8809 0.490694 0.8333 2.8909509 0.607441
4.95 15.2148 0.483815 0.8846 3.06830158 0.710023
5.61 15.7072 0.482456 0.8611 2.98700706 0.609506
10.4 21.2472 0.489646 1.0987 3.80806824 0.418661
10.2 21.0278 0.480301 0.875 3.03242429 0.340372
11 21.1137 0.49286 1.1096 3.84439671 0.399181
10.1 20.7267 0.473203 0.8333 2.89071415 0.327317
15.7 27.8898 0.485935 0.862 2.98702492 0.217596
15.7 27.8105 0.485751 0.7203 2.49599746 0.182662
5.51 20.8561 0.629392 1.7246 4.48330098 0.932142
5.21 20.828 0.627972 1.7942 4.66496446 1.025619
4.94 20.9318 0.642762 1.7461 4.53942727 1.051953
5.1 21.2467 0.61836 1.6396 4.26248802 0.957272
9.94 28.855 0.643904 2.1614 5.61962694 0.647546
10.3 29.0674 0.626367 2.0451 5.31664577 0.589067
10.5 29.1398 0.625158 2.0885 5.42922252 0.594838
10.2 29.5829 0.613958 1.9766 5.13893842 0.575679
15.8 44.8136 0.615064 1.1479 2.98414476 0.216755
15.8 44.764 0.615514 1.1934 3.10242769 0.22517
15.1 45.201 0.603738 1.2275 3.19131694 0.242749
15.1 45.2649 0.603012 1.2543 3.26096644 0.247512
C-1
103
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Results: Test Matrix la
Test
lalal
1ala2
1ala3
1ala4
ialb
1alb2
1alb3
1alb4
lalcl
1alc2
1alc3
1alc4
CO
Total
verag Average Average
Avg
Exh Water Load Fuel
Air
0C
(% molar) (% molar) (% by Wt) (N-m) (cc/min) (mA3/min) (g/hr)
C02
0.05
4.8 4.559773 5.29 7.90853 0.258765 0.1552
0.025 5.254286
4.85125 5.5 8.43425 0.261876 0.1713
0.05 3.683333 4.318696 5.48 8.36019 0.262048 0.1483
0.025
3.85 4.015237 6.23 7.67008 0.231821 0.1668
0.05
3.67
4.39273 5.39 7.95939 0.189765 0.2849
0.055
4.7 4.994408 5.61 8.01636 0.189983 0.3028
0.05
4.5 4.38946 5.45
7.948 0.185496 0.3043
0.06
4.55 4.421642 5.37 8.13273 0.185587 0.2916
0.1
5.23 4.826171 5.47 8.08105 0.159855 0.4398
0.105
5.46 4.962188 5.33 8.08105 0.159695 0.4488
0.104 5.513333 4.993105 5.32 8.08105 0.160049 0.4251
0.1
5.3 4.867555 5.58 8.08105 0.160061 0.3917
D-1
117
Average
Average
OC
SOC
(ug/cyl/cyc) (g/kW-hr)
4.29656576
4.74189987
4.10448693
4.63439888
7.88585791
8.37696134
8.41754975
8.0654168
12.1768377
12.416881
11.7640892
10.8427401
0.232645
0.247006
0.214764
0.212331
0.418758
0.42818
0.442812
0.430542
0.637755
0.668145
0.633742
0.557034
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U)
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LL
dz
GASFLOW (TWIST) [Land Pressures & Ring Positions]; 1200 rpm 5 Nm 101.3 KPa Pressure
4~
0
Cu
Co
0.
-j
'a
-360
-270
-180
-90
0
CrankAngle
90
180
270
360
0.9
0.8
0.7
= 0.6
75 0.5
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nc 0.4
0.3
0.2
0.1
0
-360
-270
-180
-90
0
CrankAngle
D-6
122
90
100
270
360
GASFLOW (TWIST) [Land Pressures & Ring Positions]; 1200 rpm 5 Nm 90KPa Pressure
4n
8
2
U3
.0
a3
0.
-j
0
CrankAngle
1
0.9
0.8
0.7
= 0.6
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a,
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a:
- 0.4
0.3
0.2
0.1
C)
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-270
-180
-90
0
CrankAngle
D-7
123
90
180
270
360
GASFLOW (TWIST) [Land Pressures & Ring Positions]; 1200 rpm 5 Nm 80KPa Pressure
'a
rc
a
CL
-j
-360
-270
-180
-90
0
CrankAngle
90
180
270
360
0.9
0.8
0.7
, 0.6
._l
Ca
a 0.5
r
- 0.4
0.3
0.2
0.1
1
-360
-270
-180
-90
0
CrankAngle
D-8
124
90
180
270
360
II
A
C
c
0)
0
g0s
0
c
iz
ct
0
c
qMoj
(oos/6m) A
125
O
co
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Co
I-N
00
co
zE
0
a)
to
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a.'
ru
0
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N
n
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0,
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C
0
0
0
10
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C
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la
N
0
Co
0CD
NID
N-
CD
UL)
(en
N
T
(seq) eJnssOJd
126
n
0I
o
E
Z
Ln
4-
0c I
C
Cr
4
0
CD
COLaA
(seq) .jn
SSaJd
127
Results: Test Matrix 2
Test
Total
Avera Average Average Avg
OC
Air
Exh Water Load Fuel
(% molar) (% molar) (% by Wt) (N-m) (cc/min) (mA3/min) (g/hr)
CO
C02
2ala1
2a1a2
2a1a3
2a1a4
2a2al
2a2a2
2a2a3
2a2a4
2bla1
2b1a2
2b1a3
2b1a4
0.05
0.05
0.05
0.05
0.25
0.23
0.23
0.23
0.03
0.03
0.03
0.03
4.56
4.56
4.56
4.56
6.36
6.54
6.54
6.54
4.21
4.21
4.21
4.21
4.8243
4.823718
4.82402
4.823134
5.931087
6.027079
6.026829
6.026828
4.6091
4.609314
4.610089
4.610365
2b2al
0.06
6.19
6.04
4.9
4.79
4.69
4.88
10.7
10.9
10.9
10.8
5.23
5.08
5.08
4.93
8.56323
8.64624
8.58765
8.72437
12.5541
12.6335
12.6644
12.6693
16.9373
16.8648
16.6182
16.5169
0.250491
0.250193
0.249896
0.249918
0.245454
0.245626
0.245454
0.245546
0.47122
0.471002
0.470659
0.470144
9.15 20.4734 0.464995
E-1
128
Average
Average
SOC
OC
(ug/cyl/cyc) (g/kW-hr)
1.5301
1.4423
1.4509
1.4715
3.0324
3.008
3.2445
3.1669
11.213
11.293
10.951
10.561
42.3509599
39.9210285
40.1546682
40.7275206
83.9344431
83.2588171
89.7957255
87.6533157
155.402173
156.520247
151.842293
146.434238
?????
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2.476519
2.385133
2.450431
2.39188
2.252919
2.190326
2.358925
2.329223
8.508485
8.829824
8.5624
8.501537
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Results: Test Matrix 3
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~l
Total
Avera Average Average
Avg
Average
Exh Water Load Fuel
Air
OC
OC
(% molar) (% molar) (% by Wt) (N-m) (cc/min) (m^3/min) (g/hr)
(ug/cyl/cyc)
-
Test
CO
y
|
i
3ala1
3a1 a2
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3a2a1
3a2a2
3bla1
0.03
0.03
0.03
0.15
0.15
0.06
4
4
4
5.6
5.6
4.35
3.610822 5.41
3.610692 5.51
3.610715
5.5
5.355666 10.6
5.355666 10.6
4.604876 5.53
3b1 a2
0.06
4.35
4.604561
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3b2a1
0.06
0.7
4.35 4.604282
5.1 4.519255
9.05273
9.07471
9.06738
12.1102
12.1102
17.9854
5.58 18.0176
0.7
5.1
4.519389
9.38 21.5051
3b2a3
0.7
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4.519642
9.38 21.3542
,
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0.256949
0.256547
0.256525
0.253169
0.253169
0.483308
0.7999
0.7304
0.7538
1.6327
1.5146
6.6613
22.2186508
20.2898182
20.8889814
45.3540729
42.0714995
92.5180861
0.481396
6.4292 89.2939037
I-
Average
SOC
(g/kW-hr)
1.177124
1.054624
1.089976
1.225974
1.137242
4.790795
4.582432
5.5 18.0648 0.480217 6.872 95.4437592 4.968483
9.48 21.5719 0.475192 11.896 165.220039 4.991966
3b2a2
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135
0.475249
12.265 170.341682
5.201561
0.47478 12.135 168.548588 5.146803
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