This document summarizes an experimental study of a modified diesel engine operating in homogeneous charge compression ignition (HCCI) combustion mode compared to the original diesel combustion mode. The study found that HCCI combustion provided very low NOx and soot emissions but had challenges with hydrocarbon emissions, fuel consumption, ignition timing control, and performance at high loads. Cooled exhaust gas recirculation was used to control in-cylinder NOx production. Test results showed significant reductions in NOx and smoke emissions for HCCI combustion compared to diesel mode, along with generally higher hydrocarbon and carbon monoxide emissions due to early fuel injection timing and fuel adhering to cylinder walls.

1. Thermal Energy Conversion Control Lab. Chonbuk Nat’I Univ.
Experimental study of the performances of a modified
diesel engine operating in homogeneous charge
compression ignition (HCCI) combustion mode
versus the original diesel combustion mode
Thermal PowerGroup,DepartmentofEnergyEngineering,UniversityofSeville,EscuelaTe´cnica Superiorde Ingenieros
deSevilla, Camino delos Descubrimientos,s/n41092Sevilla,Spain
Energy 34 (2009) 159–171
Nandi Sudheer
201455278

2. Abstract
 Homogeneous charge compression ignition(HCCI)combustion mode provides very low NOx and soot emissions;
however , it has some challenges associated with hydrocarbon(HC) emissions, fuel consumption, difficult
control of start of ignition and bad behavior to high loads.
 Cooled exhaust gas recirculation(EGR) is a common way to control in-cylinder NOx production in diesel and
HCCI combustion mode.
 This work is intended to characterize an engine that has been modified from the base diesel engine
(FL1906DEUTZ-DITER) to work in HCCI combustion mode.
 It shows the experimental results for the modified diesel engine in HCCI combustion mode fueled with
commercial diesel fuel compared to the diesel engine mode.
 An experimental installation , in conjunction with systematic tests to determine the optimum crank angle of
fuel injection, has been used to measure the evolution of the cylinder pressure and to get an estimate of the heat
release rate from a single-zone numerical model. From these the angle of start of combustion has been obtained.
 The performances and emissions of HC, CO and the huge reduction of NOx and smoke emissions of the engine
are presented.
 These results have allowed a deeper analysis of the effects of external EGR on the HCCI operation mode, on
some engine design parameter sandal soon NOx emission reduction.
Thermal Energy Conversion Control Lab. Chonbuk Nat’I Univ. 2

3. Introduction
Thermal Energy Conversion Control Lab. Chonbuk Nat’I Univ.
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 Homogeneous charge compression ignition(HCCI)combustion integrates features of both
spark ignition(SI) and compression ignition (CI) engines, obtaining promisingly the high
efficiency of a diesel engine with virtually almost no NOx and soot emissions

4. Deutz FL1 906 engine characteristics.
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5. Experimental system
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6. Start of combustion versus injection angle with a relative fuel
–air equivalence ratio of 0.3 at different speeds and different
intake temperatures
Start of combustion versus injection angle with a
relative fuel–air ratio of 0.8 at different speeds a
nd different intake temperatures.
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7. SFC in HCCI combustion mode without EGR versus diesel combustion mode
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8. Combustion chamber pressure and HHR in HCCI combustion mode versus crank
angle for the same engine torque and for different inlet temperature and angular
speed
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9. Combustion chamber pressure versus
Crack angle at a compression ratio of 15:1,
Angular speed of 1500RPM and fuel
Consumption 2.6e5 kg/cycle for different
EGR rates.
Combustion chamber pressure versus crank angle at
a compression ratio of 15:1,angular speed of
2400RPM and fuel consumption of 2.97e5 kg/cycle
for different EGR rates.
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10. SFC versus percentage of EGR in HCCI and Diesel Combustion mode
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11. Maximum torque versus fuel consumption and angular speed corresponding to EGR rate
Compression ratio is 15:1
Maximum percentage of EGR versus fuel consumption and angular speed compression
ratio 15:1
Thermal Energy Conversion Control Lab. Chonbuk Nat’I Univ. 11

12. 1.Maximum Torque versus fuel consumption and angular speed corresponding to the EGR
rate Compression ratio is 19:1.
2.Maximum percentage of EGR (Stable combustion) versus fuel consumption and angular
speed. Compression ratio is 19:1
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13. NO푋 Emissions in HCCI and Diesel Mode Both with without EGR
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14. The effect of EGR on CO and smoke emissions in HCCI combustion mode
versus diesel combustion mode
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15. HC emissions in diesel and HCCI combustion mode without EGR.
Thermal Energy Conversion Control Lab. Chonbuk Nat’I Univ. 15

16. Emissions of NOx in HCCI and diesel combustion mode with EGR
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17. Conclusions
The effects of EGR and operating conditions on HCCI combustion mode and NOx–HC–soot emissions were
studied by different strategies. The main conclusions are as follows:
1.TheignitiontiminginHCCIcombustionmodeatlargeengine loads can be delayed to an optimum timing by cold EGR.
At the same time, smoother HCCI combustion is obtained.Thebest crack angle for injection in the HCCI combustion
mode for this modified engine has been established as 45° BTDC.
2. An increase of inlet temperature at constant EGR rate has a large effect on the start of combustion in HCCI
mode, and advances it.
3. An increase of angular speed produces a decrease in the angle of start of combustion. This has a positive effect
during engine power because of diminished pressure during compression stroke.
4. The air–fuel equivalence ratio has a direct effect on HCCI timing, advancing the start of combustion when the
air–fuel equivalence ratio diminishes. This has a negative effect on engine power because the pressure increases
during compression stroke.
5. Soot emissions are negligible in the HCCI combustion mode, and are independent of the EGR rate.
6. Engines running in the HCCI combustion mode with EGR reach ultra-low NOx emissions.
7. In general the CO and HC are higher in the HCCI combustion mode than in the diesel mode due to early injection
and fuel adhering to the cylinder walls.
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18. The Future of HCCI
• The future of HCCI looks promising specially with partial HCCI mode.
• Major companies such as GM, Mercedes-Benz, Honda, and Volkswagen have invested
in HCCI research.
Company Company Technology
Thermal Energy Conversion Control Lab. Chonbuk Nat’I Univ.
Estimated Year of Commerc
ialization
General Motor
s
Saturn-Aura pHCCI Test Vehicle is on the Road.
Opel-Vectra pHCCI 2015
Mercedes Dies-otto PHCCI Test Vehicle is on the Road.
Volkswagen Touran CCS(Combined Combustion Spark) 2015
GCI(Gasoline Compression Ignition)
Ford pHCCI 2015

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21. Thank you for listening
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