Implementation of Advanced Fuels
and Combustion for Internal
Combustion Engines
Dr. J.A. Drallmeier
Dr. Umit Koylu, Dr. Jag Sarangapani, Dr. Hai Xiao
Department of Mechanical and Aerospace Engineering
Department of Electrical and Computer Engineering
Missouri University of Science and Technology
Mechanical Engineering / Electrical Engineering
Overview
• Nature of Advanced Combustion Modes in
Reciprocating Internal Combustion Engines
• Fuel Flexibility of Advanced Combustion Modes
• Advanced Cyclic Feedback Control
• Sensors for Cyclic Control
• Advanced Engine Simulations for HydrogenFueled Engines
• Future Directions
Mechanical Engineering / Electrical Engineering
Advanced Combustion Modes
• SI - Low cost while meeting current emission regulations.
• CI (“Diesel”) - 30 to 40% higher thermal efficiency than SI but
NOx and soot emission control issues.
• Low Temperature Combustion (LTC) – Low NOx, negligible soot
with high thermal efficiency.
Mechanical Engineering / Electrical Engineering
Advanced Combustion Modes
Advantages of advanced LTC modes:
• Short duration combustion leading to
higher thermal efficiencies.
• Homogeneous charge prevents rich
regions and hence soot formation.
• Lower combustion temperatures
(lean) which reduces NOx formation.
• Achievable with a wide variety of
fuels.
Mechanical Engineering / Electrical Engineering
Advanced Combustion Modes
Challenges facing implementation of advanced LTC
modes:
• Mixture preparation
• High pressure rise rates leading to noise and limiting
full-load capabilities
• Control of start-of-combustion (kinetically controlled)
o
Variation with fuels
o
Variation between cycles
Mechanical Engineering / Electrical Engineering
Advanced Combustion Modes – HCCI
(Massey and Drallmeier – ORNL)
• Single cylinder Hatz engine configured for
HCCI combustion
Objectives of Work
– Benchmark a small single cylinder engine for
HCCI studies.
– Identify the viability of surface acceleration for
closed-loop combustion control.
Mechanical Engineering / Electrical Engineering
Advanced Combustion Modes - HCCI
Impact of fuel type on start-of-combustion (SOC)
Energy Release Rate (J/deg)
• SOC is controlled by chemical kinetics (not spark or injection
timing)
• Inlet temperature and fuel type dramatically impact SOC
95
• Combustion phasing
and duration impact
“efficiency”
• HCCI is very fuel
flexible if combustion
phasing and duration
can be controlled.
TRF, Ti = 190C
TRF, Ti = 180C
75
55
35
E85, Ti = 190C
E85, Ti = 180C
0.93 ms
UG, Ti = 190C
UG, Ti = 180C
Conventional
15
-5
330
340
350
360
370
380
390
Crank Angle Degree
Mechanical Engineering / Electrical Engineering
Advanced Combustion Modes - HCCI
Impact of SOC and duration on efficiency
• Single fuel with varied inlet temperature
• CE – Combustion efficiency; TE – Thermal efficiency
CE=97%
TE=34%
CE=92%
TE=34%
Energy Release Rate (J/deg)
95
75
Ti = 200C
Ti = 190C
CE=94%
TE=36%
0.93 ms
55
Ti = 185C
Ti = 180C
• However, phasing
relative to TDC is
critical
35
CE=81%
TE=32%
15
-5
330
340
350
360
370
• Shorter duration tends
toward better
efficiency (Otto cycle)
380
390
Crank Angle Degree
Mechanical Engineering / Electrical Engineering
Advanced Combustion Modes Summary
• Advanced combustion modes (LTC) provide a path to
increased fuel efficiency simultaneous with reduced
emissions and fuel flexibility.
• One critical need to implement these modes is advanced
control schemes as chemical kinetics control combustion
phasing and fuel sources and composition (bio-fuels,
petroleum based, blends, etc.) can vary widely.
• Control needs to nearly cyclic to minimized output
fluctuations and adjust for varying input conditions (fuel,
temperature, etc.)
Mechanical Engineering / Electrical Engineering
Advanced Nonlinear Adaptive Cyclic Control
(Sarangapani and Drallmeier – NSF)
• Engine dynamics expressed as
nonstrict feedback nonlinear
discrete-time systems
x1  k 1  AF  k   F  k  x1  k   R  F  k  CE  k  x2  k   d1  k 
x2  k 1  1 CE  k  F  k  x2  k    MF  k   u  k   d2  k 
Neural Network (NN)
Controller
yk   x 2 k CE k 
VT
x1
 (.)
1
2
3
 (.)
CEk  
CEmax
 ( k ) m 
u l 
1  100
x k 
 k   R 2
x1 k 
x2
Engine
WT
 (.)
y1
 (.)
y2
 (.)
ym
 (.)
xn
Inputs
 (.)
L
outputs
Hidden Layer
Control
Inputs
Measurements
NN Observer
• Engine dynamics are not
• Control design requires an
accurately known before hand;
observer to estimate total fuel and
adaptive neural networks are
air
utilized to approximate the
unknown dynamics
Mechanical Engineering / Electrical Engineering
Advanced Nonlinear Adaptive Cyclic Control
Engine Controller Timing Specifications
5
intake valve closed
start of combustion
4
3
2
SOC
exhaust valve open
example
pressure
TDC
intake valve open
begin
fuel injection
TDC
1
0
0
100
200
300
400
500
600
700
degrees
Engine Sim at 1000 RPM
5
• Controller developed for
lean and high EGR SI
engine.
• Control was performed by
microprocessor based
system driving small
perturbations on the fuel
injector pulse width.
Time series of Heat Release for Equivalence Ratio Set Point  = 0.77
4
pressure
24.167 ms
3
1200
1100
2
fuel injection
17.667 ms
1000
18.167 ms
1
0
0
0.02
0.04
0.06
time (seconds)
0.08
0.1
0.12
Heat Release(k), J
calculation
900
800
700
600
500
400
300
-500
-400
-300
-200
-100
0
k th cycle
Mechanical Engineering / Electrical Engineering
100
200
300
400
500
Advanced Nonlinear Adaptive Cyclic Control
0.04
0.04
0.035
0.035
0.03
0.03
0.025
0.02
0.025
0.02
0.015
0.015
0.01
0.01
0.005
0.005
0
0
0
0.01
0.02
HR(k)
0.03
0.04
Uncontrolled HR:  =0.97 - COV: 0.1873
HR(k+1)
Misfire
HR(k+1)
HR(k+1)
Controlled  =0.76
0.045
0
0.01
0.02
HR(k)
0.03
Heat Release for Lean Operation
Without (left) and With (right) Control
0.04
Controlled HR:  =0.97+3.4% - COV: 0.0838
1200
1200
1100
1100
1000
1000
900
900
HR(k+1)
Uncontrolled  =0.76
0.045
800
700
800
700
600
600
500
500
400
400
300
300
400
600
800
HR(k)
1000
1200
400
600
800
HR(k)
1000
Heat Release with 10% EGR Without
(left) and With (right) Control
• Adaptive critic neural network controller for lean and high EGR engine operation
on two engine reduced NOx by around 90%, unburned hydrocarbons by 30%, and
CO by 10% from stoichiometric levels.
• Fuel efficiency is enhanced by 8% from current levels.
• Misfires have been minimized
Mechanical Engineering / Electrical Engineering
1200
Sensors for Cyclic Control
These control schemes require advanced, robust, low-cost
sensors for feedback:
Vibration Based Sensors: (Massey and
Drallmeier – ORNL)
• Identify frequency bands that carry
information regarding the combustion process
with minimal structural influence.
• Increase understanding of dynamic fluidstructure interactions within the engine
combustion chamber.
• Identify the viability of surface acceleration
for closed-loop combustion control.
Mechanical Engineering / Electrical Engineering
Spectral Power (g2)
1 – 4kHz (band)
Pressure (bar)
Crank Angle
1. Load FEA
Model with
Measured
Cylinder
Pressure
40
-Y- Direction
30
Ti = 202C
Ti = 192C
Ti = 182C
20
10
0
0
35
70
105
140
Acceleration (g)
Peak Heat Release Rate (J/deg)
Time (s)
3. Extract
Structural
Modes
Power Spectral
Density
2. Compare
Measured and
Computed
Accelerations
4. Investigate Correlation
Between Cyclic Combustion
and Frequency Band
Acceleration Characteristics
Structure
Mode
Frequency (kHz)
Mechanical Engineering / Electrical Engineering
Sensors for Cyclic Control
Microphotonic Devices (Xiao – DoE)
• Devices under investigations
–
–
–
–
Fabry-Perot interferometer
Long period fiber grating
Microresonators
Tunneling device
• The differentiators of our devices
– Ultracompactness, robustness, dependable
performance
Mechanical Engineering / Electrical Engineering
Extrinsic Fabry-Perot Interferometers
Capillary tube
Fiber
Diaphragm
Holly Fiber
Ferrule
Expanded signal trace
0.6
Partial discharges in an
electric transformer
Output in volts
0.4
0.2
0
-0.2
-0.4
-0.6
0
Mechanical Engineering / Electrical Engineering
20
40
60
80
100
120
Time in us
140
160
Acoustic Sensor
180
200
Micro inline Fabry-Perot Interferometers
Miniaturized inline Fabry-Perot interferometer (FPI) fabricated
by one-step femtosecond laser micromachining
• Linear response
• Extremely small T-dependence
• No drift issue!
L
(a)
I1
30.88
Core
I2
Cavity Length (m m)
30.87
Cladding
30.86
30.85
(b)
30.84
30.83
30.82
Slope =
0.074pm/C
30.81
30.80
30.79
0
200
400
600
800
1000
1200
Temperature (C)
Mechanical Engineering / Electrical Engineering
(c)
Hydrogen Engine Simulations
(Koylu - National University Transportation Center)
Hydrogen Fuel is being considered as an engine fuel due to its unique
properties using advanced simulations
Characteristic
Higher efficiency due to higher
flame speed leading to faster
combustion
Lower emissions due to non-carbon
fuel content, only NOx at higher
loads/equivalence ratios
Hydrogen
Gasoline
Notes
Heating value
(kJ/g)
120
44.5
higher heating
value
Flame speed (m/s)
2.1
0.3
faster burning
Flammability
limits (vol%)
4-74
1-7
wider limits
Ignition energy in
air (mJ)
0.02
0.3
easier ignition
• Wide flammability limits decrease cycle by cycle variations.
• Ignition of hydrogen mixture possible with a relatively weak spark.
• Hydrogen can be mixed with other fuels (methane, biogas, diesel) to
improve their combustion and emission characteristics.
Mechanical Engineering / Electrical Engineering
Hydrogen Engine Simulations
Computational Modeling of a Hydrogen Engine using GT - Power
8
8000
Simulations
Experiments
Simulations
Experiments
7000
6000
6
NOx (ppm)
Brake Power (kW)
7
5
4
3
5000
4000
3000
2
2000
1
1000
0
0
0
0.2
0.4
0.6
0.8
1
1.2
0
1
Equivalence Ratio
Mechanical Engineering / Electrical Engineering
2
3
4
5
Brake Power (kW)
6
7
8
Future Directions
Ongoing initiatives of the Investigators:
• Develop novel control scheme capable of using an adaptive
feedback control strategy to maintain proper phasing of
combustion as well as heat release rise rates for LTC modes.
• Implement advanced combustion modes in a fuel-flexible sense
where the fuel is not known a-priori by sensing heat release and
adjusting combustion system parameters online.
• Identify novel sensor techniques which would provide sufficient
cyclic information for a nonlinear adaptive controller.
• Extend advanced engine simulations for developing hydrogen
fuel strategies.
• Develop models for hydrogen fuel-specific combustion flame
speed and NOx emission.
Mechanical Engineering / Electrical Engineering