59
CHAPTER 5
EXPERIMENTAL PERFOMANCE ANALYSIS WITH EGR
5.1
EXHAUST GAS RECIRCULATION SYSTEM
5.1.1
Introduction to EGR
The most effective way of reducing NOx emissions is to hold
combustion chamber temperatures down. Although practically, this is a
commonly used method in that it also reduces the thermal efficiency of the
engine. Probably the simplest and practical method of reducing maximum
flame temperature is to dilute the air-fuel mixture with a non-reacting gas.
This gas absorbs energy during combustion without contributing any energy
input.
The net result is a lower flame temperature. Any non-reacting gas
would work as diluents. Those gases with larger specific heats would absorb
the most energy per unit mass and would therefore require the least amount,
thus less CO2 would be required than argon for the same maximum
temperature. However, neither CO2 nor argon is readily available for use in an
engine. Air is available as diluents but is not totally non-reacting. Adding air
changes the air-fuel ratio and combustion characteristics. The one nonreacting gas that is available to use in an engine is exhaust gas and this is used
in all modern automobile and other medium-size to large engines. Adding any
non-reacting neutral gas to the inlet air-fuel mixture reduces flame
60
temperature and NOx generation. Exhaust gas is the one gas that is readily
available for engine use.
5.1.2
EGR Operation
The purpose of the EGR system is to precisely regulate exhaust gas
to engine under different operating conditions, which would compromise
good engine performance. The precise amount of exhaust gas, which must be
metered into the intake manifold, varies significantly as engine load changes.
This results in the EGR system operating on a fine line between good NO x
control and engine performance. If too much exhaust is metered in the engine
the performance will suffer, if too little EGR flows, the engine may knock.
5.1.3
Classification of EGR Systems
EGR systems have been classified on the basis of EGR temperature,
configuration and pressure.
5.1.3.1
Classification Based on Temperature
Hot EGR
Exhaust gas is re-circulated without being cooled, resulting in
increased intake charge temperature.
Fully Cooled EGR
Exhaust gas is fully cooled before mixing with fresh intake air,
using a water-cooled heat exchanger. In this case, the moisture present in the
exhaust gas may condense and the resulting water droplets may cause
undesirable effects inside the engine cylinder.
61
Partly Cooled EGR
To avoid water condensation, the temperature of the exhaust gas is
kept just above its dew point temperature.
5.1.3.2
Classification Based on Configuration
Long Route System
In a long route system the pressure drop across the air intake and the
stagnation pressure in the exhaust gas stream make the EGR possible. The
exhaust gas velocity creates a small stagnation pressure, which in
combination with low pressure after the intake air, gives rise to a pressure
difference to accomplish EGR across the entire torque/speed envelope of the
engine.
Short Route System
This system differs mainly in the method used to setup a positive
pressure difference across the EGR circuit. Another way of controlling the
EGR-rate is to use Variable Nozzle Turbine (VNT). Most of the VNT systems
have single entrance, which reduces the efficiency of the system by exhaust
pulse separation. Cooled EGR should be supplied effectively.
5.1.3.3
Classification Based on Pressure
There are two different routes for EGR, namely low-pressure and
high-pressure route systems.
Low Pressure Route System
The passage for EGR is provided from downstream of the turbine to
the upstream side of the compressor. It is found that by using the low-pressure
62
route method EGR is possible up to a high load region, with significant
reduction in NOx.
High Pressure Route System
The EGR is passed from upstream of the turbine to downstream of
the compressor. In the high-pressure route EGR system, although EGR is
possible in the high load regions, the excess air ratio decreases and fuel
consumption increases remarkably.
5.1.4
Advantages and Disadvantages of using EGR
With the use of EGR, there is a trade-off between reduction in NO x
on one hand and increase in products of incomplete combustion like soot, CO
and unburned hydrocarbon emissions on the other hand. It is seen that HC
continued to decrease until the EGR rate reached a certain level and the fuel
economy decreased. It has been indicated that for more than 60% EGR
particulate emission increased significantly. Therefore EGR must be coupled
with a particulate filtration system not only to lower the emission of soot to
the atmosphere, but also to provide an exhaust stream that is clean enough to
be re-circulated. The changes in the oxygen concentration cause the change in
the flame and hence changes the duration of combustion. It was suggested
that the flame temperature suppression is the most important factor
influencing the NOx formation.
Implementation of EGR in diesel engine has problems like increased
soot emission. A particulate matter may be introduced in to the engine
cylinders. When the engine components come into contact with a high
velocity soot particulates, particulate abrasion occurs. Moreover when much
soot builds up on the interior of the air intake manifold, the air pressure drop
increases and the volume of intake air decreases, thereby decreasing the
63
power of the engine. Much of the soot content in the exhaust enters the engine
and the soot adheres to the surface of the combustion chamber. Soot build-up
on the surface of the combustion chamber impedes heat transfer at high
temperature; the strength of the combustion chamber weakens. Soot carried in
the blow-by gas deteriorates the properties of the lubricating oil in the
crankcase. This in turn increases friction losses and requires more frequent oil
changes. The percentage of exhaust gas re-circulated in the engine is given by
Equation (5.1).
%
5.2
=
100
(5.1)
EXPERIMENTAL METHOD
The test engine is a single cylinder, direct injection, water cooled
Compression Ignition engine. The experimental setup is shown in Figure 5.1.
An orifice box is connected to the inlet manifold and the air mass flow rate is
measured using the manometer connected to the orifice box.
The EGR
system consists of a piping system taken from the engine exhaust pipe and an
orifice meter is to used measure the flow rate of the exhaust gases. The
amount of exhaust gas recycling into the inlet manifold is controlled by means
of two valves, one in the inlet pipe and the other in the pipe line connecting
the exhaust line and the inlet manifold. The re-circulated exhaust gas flows
through another orifice meter with inclined manometer for measuring the flow
rate, before mixing with the fresh air. Cold EGR is attained by cooling the recirculated exhaust gas. The exhaust gas recirculation line is connected to a
parallel flow heat exchanger having water as the cold fluid. Thermometers are
connected to inlet and exit of the cold and hot fluids in the heat exchanger.
The probe of exhaust gas analyzer is inserted into the exhaust pipe for
emission measurement. The engine is loaded using rope brake dynamometer.
The load on the engine as well as the time taken to consume 25 cc fuel was
64
noted and the remaining performance parameters were calculated using the
standard formulae mentioned in chapter 4. At the same time the emission
values were recorded for all engines and for all conditions by changing the
percentage of EGR.
5.2.1
Experimental Setup
Figure 5.1 Experimental Setup
1. Air inlet
2.Air inlet Orifice box
3. Air inlet manometer
4.Air inlet control valve
5. CI engine
6.Exhaust gas control valve
7. EGR control valve
8.Heat exchanger
9. Water inlet
10.Water outlet
11. Exhaust gas Orifice box
12.Exhaust gas manometer
13. EGR pipe
14.Particulate filter
65
5.3
EXHAUST GAS ANALYSER
The Kane automotive range of emission analysers has been designed
to be used for Petrol, LPG and Diesel powered vehicles. It can measure
carbon monoxide, unburned hydrocarbons, Oxygen, Carbon dioxide and
Nitrous oxide. The analyser is supplied with an RS232 output enabling
communication between the analyser and a PC. It is battery powered to give
true portability in the workshop environment. The battery can be charged via
an adapter or 12V capacity battery and the specifications are listed in Table
5.1.
Table 5.1 Exhaust Gas Analyser Specifications
Parameter
Resolution
Accuracy
Range
Carbon monoxide
0.01%
+/-5% of reading
+/-5% volume
0-10%
Over-range 20%
Oxygen
0.01%
+/-5% of reading
+/-0.1% volume
0-21%
Over-range 48%
Hydrocarbon
1ppm
+/-5% of reading
+/-12ppm volume
0-5000ppm
Over-range:
10000ppm
Carbon Dioxide
0. 1%
+/-5% of reading
+/-0.5% volume
0-16%
Over-range 25%
Nitrous oxide
1ppm
0-4000ppm+/-4%or
25ppm;40005000ppm +/-5%
0-5000ppm
Oil temperature
1.0oC
+/-2.0oC±0.3%of
reading+/-3.6oF±of
reading
0-150oC
32-302oC
Carbon monoxide
corrected CO
0.01%
Calculated
0-15%
66
5.4
RESULTS AND DISCUSSION
The trends of thermal efficiency are shown in Figures 5.3, 5.8, 5.13
and 5.18. Thermal efficiency is found to have slightly increased with EGR at
lower engine loads. The possible reason may be re-burning of hydrocarbons
that enter the combustion chamber with the re-circulated exhaust gas. At part
loads, the exhaust gas has less CO2 and fairly high amount of O2. Also, partlycooled EGR acts like a pre-heater of the intake mixture. When this exhaust
gas is re-circulated in the cylinder, the unburned HC in the exhaust gas was
burned because of sufficient O2 available in the combustion chamber and
reasonably increasing intake temperatures. At higher engine loads, the
thermal efficiency remains unaffected by EGR. At higher loads, the exhaust
gas has higher amount of CO2, which reduces the maximum temperature in
the combustion chamber along with oxygen availability, therefore re-burning
of HC is not significant.
Figures 5.2, 5.7, 5.12 and 5.17 represent comparison of SFC for all
piston engines performance with different percentage of EGR. SFC is lower at
lower loads for engine operated with EGR compared to without EGR.
However, at higher engine loads, SFC with EGR is almost similar to that of
without EGR. At higher loads, the amount of fuel supplied to the cylinder is
increased at higher rate and the oxygen available for combustion gets reduced.
Thus, the air fuel ratio is changed and this increases the BSFC. The exhaust
gas temperatures have been increased with load. Exhaust gas temperature
decreases with increase in EGR rate. The reasons for temperature reduction
are relatively lower availability of oxygen for combustion and higher specific
heat of intake air mixture.
The effect of EGR on unburned HC and CO emissions are
incremental with increasing EGR. Lower excess oxygen concentration results
in rich air-fuel mixtures at different locations inside the combustion chamber.
67
This heterogeneous mixture does not burn completely and results in higher
HC and CO emissions. At part loads, lean mixtures are harder to ignite
because of heterogeneous mixture and produce higher amount of HC and CO.
Figures 5.22 to 5.25 shows the main benefit of EGR in reducing NO x
emissions from a diesel engine. The degree of reduction in NO x is higher at
maximum loads. The reasons for reduction in NOx emissions using EGR in
diesel engines are reduced oxygen concentration and decreased flame
temperatures in the combustible mixture. At the part load, O 2 is available in
sufficient quantity but at high loads, the availability of O 2 reduces drastically,
therefore NOx is reduced more at higher loads compared to part loads. The
NOx values were decreased due to the EGR addition up to 15% but if
increasing beyond this limit, NO x values were increasing slowly and exceed
the initial EGR percentage benefits.
HEMISPHERE
0.6
0.5
0.4
Without EGR
0.3
5% EGR
0.2
10% EGR
15% EGR
0.1
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.2 Specific Fuel Consumption of Hemisphere Piston Engine with
EGR
68
HEMISPHERE
50
45
40
35
30
25
20
15
10
5
0
Without EGR
5% EGR
10% EGR
15% EGR
20% EGR
0
Figure 5.3
5
10
Load kg
15
20
Brake Thermal Efficiency of Hemisphere Piston Engine
with EGR
HEMISPHERE
80
70
60
50
Without EGR
40
5% EGR
30
10% EGR
20
15% EGR
10
20% EGR
0
0
Figure 5.4
5
10
Load kg
15
20
Indicated Thermal Efficiency of Hemisphere Piston Engine
with EGR
69
HEMISPHERE
80
70
60
50
Without EGR
40
5% EGR
30
10% EGR
20
15% EGR
10
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.5 Mechanical Efficiency of Hemisphere Piston Engine with
EGR
HEMISPHERE
8
7
6
5
Without EGR
4
5% EGR
3
10% EGR
2
15% EGR
20% EGR
1
0
0
Figure 5.6
5
10
Load kg
15
20
Indicated Mean Effective Pressure of Hemisphere Piston
Engine with EGR
70
Table 5.2
Performance tabulation for Hemisphere piston engine with
5% EGR
Load kg
SFC
kg/kW-hr
0
30.9051
0
IMEP
bar
2.170296
46.89555
39.767
3.603168
56.90471
5.036039
65.37374 66.45037
6.468911
BT
0
%
IT
%
5
0.445306
18.64895
10
0.266557
31.15472 54.74893
15
0.191167
43.44109
Table 5.3
mech
%
Performance tabulation for Elliptical piston engine with 5%
EGR
Load kg
SFC
kg/kW-hr
BT
0
%
0
IT
%
27.66505
mech
%
0
IMEP bar
1.953266
5
0.440128
18.86835 44.58937 42.31581
3.386138
10
0.266557
31.15472 52.38951 59.46748
4.81901
15
0.233648
35.54271 51.69311 68.75714
6.251882
Table 5.4
Performance tabulation for Ellipsoid piston engine with 5%
EGR
Load kg
SFC
kg/kW-hr
0
BT
%
IT
%
mech
%
IMEP bar
0
31.40356
0
2.170296
5
0.427695
19.41685
48.82654
39.767
3.603168
10
0.259254
32.03232
56.29116
56.90471
5.036039
15
0.221351
37.5173
56.45914
66.45037
6.468911
71
Table 5.5
Performance tabulation for Double concave piston engine
with 5% EGR
Load kg
SFC
kg/kW-hr
0
BT
%
0
IT
%
31.07125
mech
%
IMEP bar
0
2.170296
39.767
3.603168
5
0.437584
18.97805 47.72311
10
0.259254
32.03232 56.29116 56.90471
5.036039
15
0.210284
39.4919
6.468911
59.43067 66.45037
ELLIPTICAL
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
Without EGR
5% EGR
10% EGR
15% EGR
20% EGR
0
5
10
Load kg
15
20
Figure 5.7 Specific Fuel Consumption of Elliptical Piston Engine with
EGR
72
ELLIPTICAL
45
40
35
30
Without EGR
25
20
15
10
5
5% EGR
10% EGR
15% EGR
20% EGR
0
0
Figure 5.8
5
10
Load kg
15
20
Brake Thermal Efficiency of Elliptical Piston Engine with
EGR
ELLIPTICAL
70
60
50
Without EGR
40
5% EGR
30
10% EGR
20
15% EGR
10
20% EGR
0
0
Figure 5.9
5
10
Load kg
15
20
Indicated Thermal Efficiency of Elliptical Piston Engine
EGR
73
ELLIPTICAL
90
80
70
60
Without EGR
50
40
30
20
10
5% EGR
10% EGR
15% EGR
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.10 Mechanical Efficiency of Elliptical Piston Engine with EGR
ELLIPTICAL
7
6
5
Without EGR
4
5% EGR
3
10% EGR
2
15% EGR
1
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.11 Indicated Mean Effective Pressure of Elliptical Piston
Engine with EGR
74
Table 5.6
Performance tabulation for Hemisphere piston engine with
10% EGR
Load kg
SFC
kg/kW-hr
ther
0
%
0
IT
%
40.32063
mech
% IMEP bar
0
2.893728
5
0.461598
17.99075
54.32363 33.11773
4.3266
10
0.270365
30.71592
61.73179 49.75706
5.759471
15
0.2035
40.8083
68.27949 59.76655
7.192343
Table 5.7
Performance tabulation for Elliptical piston engine with
10% EGR
Load kg
SFC
kg/kW-hr
0
%
ther
IT
%
mech
%
IMEP bar
0
26.44656
0
1.80858
5
0.411424
20.18475
45.66207
44.20463
3.241452
10
0.25749
32.25172
52.60588
61.3082
4.674323
15
0.217535
38.1755
54.23729
70.38608
6.107195
Table 5.8
Performance tabulation for Ellipsoid piston engine with
10% EGR
Load kg
SFC
kg/kW-hr
0
ther
%
IT
%
mech
%
IMEP bar
0
36.53226
0
2.459669
5
0.402671
20.62355
56.02594
36.81071
3.89254
10
0.250669
33.12932
61.56422
53.81261
5.325412
15
0.212051
39.1628
61.57176
63.60513
6.758284
75
Table 5.9
Performance tabulation for Double concave piston engine
with 10% EGR
Load kg
SFC
kg/kW-hr
0
%
ther
0
IT
%
33.49714
mech
% IMEP bar
0
2.314982
5
0.430126
19.30715
50.50025 38.23179
3.747854
10
0.25575
32.47112
58.70168 55.31548
5.180726
15
0.208546
39.821
61.26625 64.99663
6.613598
ELLIPSOID
0.5
0.45
0.4
0.35
0.3
Without EGR
0.25
5% EGR
0.2
10% EGR
0.15
0.1
15% EGR
20% EGR
0.05
0
0
5
10
Load kg
15
20
Figure 5.12 Specific Fuel Consumption of Ellipsoid Piston with EGR
76
ELLIPSOID
45
40
35
30
Without EGR
25
20
15
10
5
5% EGR
10% EGR
15% EGR
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.13 Brake Thermal Efficiency of Ellipsoid Piston Engine with
EGR
ELLIPSOID
70
60
50
Without EGR
40
5% EGR
30
10% EGR
20
15% EGR
10
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.14 Indicated Thermal Efficiency of Ellipsoid Piston Engine
with EGR
77
ELLIPSOID
80
70
60
50
Without EGR
40
5% EGR
30
10% EGR
15% EGR
20
20% EGR
10
0
0
5
10
Load kg
15
20
Figure 5.15 Mechanical Efficiency of Ellipsoid Piston Engine with EGR
ELLIPSOID
8
7
6
5
Without EGR
4
5% EGR
3
10% EGR
2
15% EGR
1
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.16 Indicated Mean Effective Pressure of Ellipsoid Piston
Engine with EGR
78
Table 5.10
Performance tabulation for Hemisphere piston engine with
15% EGR
Load kg
SFC
kg/kW-hr
0
ther
%
IT
%
mech
%
IMEP bar
0
30.57278
0
2.170296
5
0.473138
17.55196
44.13698
39.767
3.603168
10
0.276285
30.05772
52.82115
56.90471
5.036039
15
0.221351
37.5173
56.45914
66.45037
6.468911
Table 5.11
Performance tabulation for Elliptical piston engine with
15% EGR
Load kg
SFC
kg/kW-hr
0
ther
%
IT
%
mech
%
IMEP bar
0
28.08044
0
1.880923
5
0.407
20.40415
47.18856
43.2396
3.313795
10
0.242635
34.22631
56.69066
60.37381
4.746667
15
0.208546
39.821
57.24527
69.56208
6.179538
Table 5.12
Performance tabulation for Ellipsoid piston engine with
15% EGR
Load kg
SFC
kg/kW-hr
0
ther
%
0
IT
%
38.8806
mech
%
0
IMEP bar
2.604355
5
0.407
20.40415
57.49026 35.49149
4.037227
10
0.242635
34.22631
65.3308
52.38925
5.470099
15
0.208546
39.821
63.94691 62.27196
6.90297
79
Table 5.13
Performance tabulation for Double concave piston engine
with 15% EGR
Load kg
SFC
kg/kW-hr
0
ther
%
IT
%
mech
%
IMEP bar
0
33.14267
0
2.459669
5
0.450608
18.42955
50.06574
36.81071
3.89254
10
0.25575
32.47112
60.34109
53.81261
5.325412
15
0.213848
38.8337
61.05435
63.60513
6.758284
DOUBLE CONCAVE
0.6
0.5
0.4
Without EGR
0.3
5% EGR
0.2
10% EGR
15% EGR
0.1
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.17 Specific Fuel Consumption of Double concave Piston
Engine with EGR
80
DOUBLE CONCAVE
45
40
35
30
Without EGR
25
20
15
10
5
5% EGR
10% EGR
15% EGR
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.18 Brake Thermal Efficiency of Double concave Piston Engine
with EGR
DOUBLE CONCAVE
70
60
50
Without EGR
40
5% EGR
30
10% EGR
20
15% EGR
10
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.19 Indicated Thermal Efficiency of Double concave Piston
Engine with EGR
81
DOUBLE CONCAVE
80
70
60
50
Without EGR
40
5% EGR
30
10% EGR
20
15% EGR
10
20% EGR
0
0
5
10
Load kg
15
20
Figure 5.20 Mechanical Efficiency of Double concave Piston Engine with
EGR
DOUBLE CONCAVE
8
7
6
5
Without EGR
4
5% EGR
3
10% EGR
2
15% EGR
20% EGR
1
0
0
5
10
Load kg
15
20
Figure 5.21 Indicated Mean Effective Pressure of Double concave Piston
Engine with EGR
82
Table.5.14
Performance tabulation for Hemisphere piston engine with
20% EGR
Load kg
SFC
kg/kW-hr
0
ther
%
0
IT
%
37.68428
mech
%
0
IMEP bar
2.604355
5
0.479127
17.33256 48.83581 35.49149
4.037227
10
0.278317
29.83832 56.95505 52.38925
5.470099
15
0.233648
35.54271 57.07658 62.27196
6.90297
Table 5.15
Performance tabulation for Elliptical piston engine with
20% EGR
Load kg
SFC
kg/kW-hr
0
ther
%
0
IT
%
18.74245
mech
%
0
IMEP bar
1.302178
5
0.415946
19.96535 38.10963 52.38925
2.735049
10
0.264693
31.37412 45.63034 68.75714
4.167921
15
0.213848
38.8337
5.600793
Table 5.16
50.59758 76.75012
Performance tabulation for Ellipsoid piston engine with
20% EGR
Load kg
SFC
kg/kW-hr
0
ther
%
IT
%
mech
%
IMEP bar
0
38.09413
0
2.749041
5
0.427695
19.41685
56.66912
34.26355
4.181913
10
0.268447
30.93532
60.61086
51.03924
5.614785
15
0.219426
37.8464
62.04986
60.99354
7.047657
83
Table 5.17
Performance tabulation for Double concave piston engine
with 20% EGR
Load kg
SFC
kg/kW-hr
0
ther
%
0
IT
%
32.83251
mech
%
0
IMEP bar
2.749041
5
0.494785
16.78406 48.98517 34.26355
4.181913
10
0.27231
30.49652 59.75113 51.03924
5.614785
15
0.227334
36.53001
7.047657
59.8916
60.99354
Hemisphere
550
500
450
400
5 % EGR
350
10 % EGR
15 % EGR
300
20 % EGR
250
200
0
5
10
15
Load kg
20
25
Figure 5.22 NOx emission of Hemisphere Piston Engine
84
Elliptical
550
500
450
400
5 % EGR
350
10 % EGR
15 % EGR
300
20 % EGR
250
200
0
5
10
15
Load kg
20
25
Figure 5.23 NOx emission of Elliptical Piston Engine
Ellipsoid
500
450
400
5 % EGR
350
10 % EGR
15 % EGR
300
20 % EGR
250
200
0
5
10
15
Load kg
20
25
Figure 5.24 NOx emission of Ellipsoid Piston Engine
85
Double concave
600
550
500
450
5 % EGR
400
10 % EGR
350
15 % EGR
300
20 % EGR
250
200
0
5
10
15
Load kg
20
25
Figure 5.25 NOx emission of Double concave Piston Engine
Table 5.18 Emission of NOx for all engines with 5% EGR
Hemisphere
Elliptical
Ellipsoid
Double
concave
NOx ppm Vol
NOx ppm
Vol
NOx ppm
Vol
NOx ppm
Vol
0
382
376
348
395
5
418
410
390
432
10
458
451
436
470
15
520
494
467
532
Load
kg
86
Table 5.19 Emission of NOx for all engines with 10% EGR
Load
kg
0
5
10
15
Hemisphere
NOx ppm Vol
364
401
435
502
Elliptical
Ellipsoid
NOx ppm
Vol
358
391
432
475
NOx ppm
Vol
330
374
416
450
Double
concave
NOx ppm
Vol
374
412
448
512
Table 5.20 Emission of NOx for all engines with 15% EGR
Load
kg
0
5
10
15
Hemisphere
NOx ppm Vol
374
409
448
507
Elliptical
Ellipsoid
NOx ppm
Vol
368
400
442
492
NOx ppm
Vol
339
380
427
455
Double
concave
NOx ppm
Vol
386
422
461
524
Table 5.21 Emission of NOx for all engines with 20% EGR
Load
kg
0
5
10
15
Hemisphere
NOx ppm Vol
394
431
469
529
Elliptical
Ellipsoid
NOx ppm
Vol
388
422
463
521
NOx ppm
Vol
357
399
448
475
Double
concave
NOx ppm
Vol
407
444
482
546