The use of natural gas in compression ignition (CI) engines as a supplement to diesel under dual-fuel combustion mode is a promising technique to increase efficiency and reduce emissions. In this study, the effect of dual-fuel operating mode on combustion characteristics, engine performance and pollutant emissions of a diesel engine using natural gas as primary fuel and neat diesel as pilot fuel, has been examined. Natural gas (99% methane) was port injected into an AVL 5402 single cylinder diesel research engine under various engine operating conditions and up to 90% substitution was achieved. In addition, neat diesel was also tested as a baseline for comparison. The experiments were conducted at three different speeds—1200, 1500, and 2000 rpm, and at different diesel-equivalent loads (injection quantity)—15, 20 (7 bar IMEP), and 25 mg/cycle. Both performance and emissions data are presented and discussed. The performance was evaluated through measurements of in-cylinder pressure, power output and various exhaust emissions including unburned hydrocarbons (UHCs), carbon monoxide (CO), nitrogen oxides (NOx), and soot. The goal of these experiments was to maximize the efficiency. This was done as follows—the compressed natural gas (CNG) substitution rate (based on energy) was increased from 30% to 90% at fixed engine conditions, to identify the optimum CNG substitution rate. Then using that rate, a main injection timing sweep was performed. Under these optimized conditions, combustion behavior was also compared between single, double, and triple injections. Finally, a load and speed sweep at the optimum CNG rate and timings were performed. It was found that a 70% CNG substitution provided the highest indicated thermal efficiency (ITE). It appears that dual-fuel combustion has a maximum brake torque (MBT) diesel injection timing for different conditions which provides the highest torque. Based on multiple diesel injection tests, it was found that the conditions that favor pure diesel combustion, also favor dual-fuel combustion because better diesel combustion provides better ignition and combustion for the CNG-air mixture. For 70% CNG dual-fuel combustion, multiple diesel injections showed an increase in the efficiency. Based on the experiments conducted, diesel-CNG dual-fuel combustion is able to achieve similar efficiency and reduced emissions relative to pure diesel combustion. As such, CNG can be effectively used to substitute for diesel fuel in CI engines.

References

References
1.
McTaggart-Cowan
,
G. P.
,
Jones
,
H. L.
,
Rogak
,
S. N.
,
Bushe
,
W. K.
,
Hill
,
P. G.
, and
Munshi
,
S. R.
,
2007
, “
The Effects of High-Pressure Injection on a Compression–Ignition, Direct Injection of Natural Gas Engine
,”
ASME J. Eng. Gas Turbines Power
,
129
(
2
), pp.
579
588
.
2.
Olsen
,
J.
,
Crookes
,
R. J.
, and
Bob-Manuel
,
K. D. H.
,
2007
, “
Experiments in Dual Fuelling a Compression Ignition Engine by Injecting Di-Methyl Ether as a Pilot Fuel to Ignite Varying Quantities of Natural Gas
,”
SAE
Technical Paper No. 2007-01-3624.
3.
McTaggart-Cowan
,
G. P.
,
Reynolds
,
C. C. O.
, and
Bushe
,
W. K.
,
2006
, “
Natural Gas Fuelling for Heavy‐Duty On‐Road Use: Current Trends and Future Direction
,”
Int. J. Environ. Stud.
,
63
(
4
), pp.
421
440
.
4.
Papagiannakis
,
R. G.
, and
Hountalas
,
D. T.
,
2004
, “
Combustion and Exhaust Emission Characteristics of a Dual Fuel Compression Ignition Engine Operated With Pilot Diesel Fuel and Natural Gas
,”
Energy Convers. Manage.
,
45
(
18
), pp.
2971
2987
.
5.
Papagiannakis
,
R. G.
,
Kotsiopoulos
,
P. N.
,
Zannis
,
T. C.
,
Yfantis
,
E. A.
,
Hountalas
,
D. T.
, and
Rakopoulos
,
C. D.
,
2010
, “
Theoretical Study of the Effects of Engine Parameters on Performance and Emissions of a Pilot Ignited Natural Gas Diesel Engine
,”
Energy
,
35
(
2
), pp.
1129
1138
.
6.
Papagiannakis
,
R. G.
,
Rakopoulos
,
C. D.
,
Hountalas
,
D. T.
, and
Rakopoulos
,
D. C.
,
2010
, “
Emission Characteristics of High Speed, Dual Fuel, Compression Ignition Engine Operating in a Wide Range of Natural Gas/Diesel Fuel Proportions
,”
Fuel
,
89
(
7
), pp.
1397
1406
.
7.
Kusaka
,
J.
,
Okamoto
,
T.
,
Daisho
,
T.
,
Kihara
,
R.
, and
Saito
,
T.
,
2000
, “
Combustion and Exhaust Gas Emission Characteristics of a Diesel Engine Dual-Fueled With Natural Gas
,”
JSAE Rev.
,
21
(
4
), pp.
489
496
.
8.
Karavalakis
,
G.
,
Durbin
,
T. D.
,
Villela
,
M.
, and
Miller
,
J. W.
,
2012
, “
Air Pollutant Emissions of Light-Duty Vehicles Operating on Various Natural Gas Compositions
,”
J. Nat. Gas Sci. Eng.
,
4
(1), pp.
8
16
.
9.
Namasivayam
,
A. M.
,
Korakianitis
,
T.
,
Crookes
,
R. J.
,
Bob-Manuel
,
K. D. H.
, and
Olsen
,
J.
,
2010
, “
Biodiesel, Emulsified Biodiesel and Dimethyl Ether as Pilot Fuels for Natural Gas Fuelled Engines
,”
Appl. Energy
,
87
(
3
), pp.
769
778
.
10.
Korakianitis
,
T.
,
Namasivayam
,
A. M.
, and
Crookes
,
R. J.
,
2011
, “
Diesel and Rapeseed Methyl Ester (RME) Pilot Fuels for Hydrogen and Natural Gas Dual-Fuel Combustion in Compression–Ignition Engines
,”
Fuel
,
90
(
7
), pp.
2384
2395
.
11.
Yoon
,
S. H.
, and
Lee
,
C. S.
,
2011
, “
Experimental Investigation on the Combustion and Exhaust Emission Characteristics of Biogas–Biodiesel Dual-Fuel Combustion in a CI Engine
,”
Fuel Process. Technol.
,
92
(
5
), pp.
992
1000
.
12.
Yang
,
B.
,
Chengxun
,
X.
,
Xing
,
W.
,
Ke
,
Z.
, and
Ming-Chia
,
L.
,
2015
, “
Parametric Investigation of Natural Gas Port Injection and Diesel Pilot Injection on the Combustion and Emissions of a Turbocharged Common Rail Dual-Fuel Engine at Low Load
,”
Appl. Energy
,
143
, pp.
130
137
.
13.
Yang
,
B.
,
Xing
,
W.
,
Chengxun
,
X.
,
Yifu
,
L.
,
Ke
,
Z.
, and
Ming-Chia
,
L.
,
2014
, “
Experimental Study of the Effects of Natural Gas Injection Timing on the Combustion Performance and Emissions of a Turbocharged Common Rail Dual-Fuel Engine
,”
Energy Convers. Manage.
,
87
, pp.
297
304
.
14.
Papagiannakis
,
R. G.
,
Hountalas
,
D. T.
,
Rakopoulos
,
C. D.
, and
Rakopoulos
,
C. D.
,
2008
, “
Combustion and Performance Characteristics of a DI Diesel Engine Operating From Low to High Natural Gas Supplement Ratios at Various Operating Conditions
,”
SAE
Technical Paper No. 2008-01-1392.
15.
Liu
,
J.
,
Fuyuan
,
Y.
,
Hewu
,
W.
,
Minggao
,
O.
, and
Shougang
,
H.
,
2013
, “
Effects of Pilot Fuel Quantity on the Emissions Characteristics of a CNG/Diesel Dual Fuel Engine With Optimized Pilot Injection Timing
,”
Appl. Energy
,
110
, pp.
201
206
.
16.
Cheenkachorn
,
K.
,
Chedthawut
,
P.
, and
Choi
,
G. H.
,
2013
, “
Performance and Emissions of a Heavy-Duty Diesel Engine Fuelled With Diesel and LNG (Liquid Natural Gas)
,”
Energy
,
53
, pp.
52
57
.
17.
Imran
,
S.
,
Emberson
,
D. R.
,
Diez
,
A.
,
Wen
,
D. S.
,
Crookes
,
R. J.
, and
Korakianitis
,
T.
,
2014
, “
Natural Gas Fueled Compression Ignition Engine Performance and Emissions Maps With Diesel and RME Pilot Fuels
,”
Appl. Energy
,
124
, pp.
354
365
.
18.
Yoshimoto
,
Y.
,
2010
, “
Combustion Characteristics of a Dual Fuel Diesel Engine With Natural Gas (Study With Fatty Acid Methyl Esters Used as Ignition Fuels)
,”
SAE
Technical Paper No. 2010-32-0050.
19.
Yoshimoto
,
Y.
,
Kinoshita
,
E.
,
Luge
,
S.
, and
Ohmura
,
T.
,
2012
, “
Combustion Characteristics of a Dual Fuel Diesel Engine With Natural Gas (Lower Limit of Cetane Number for Ignition of the Fuel)
,”
SAE
Paper No. 2012-01-1690.
20.
Yoshimoto
,
Y.
, and
Kinoshita
,
E.
,
2013
, “
Influence of Intake Air Dilution With N2 or CO2 Gases on the Combustion Characteristics of a Dual Fuel Diesel Engine With Natural Gas
,”
SAE
Technical Paper No. 2013-01-2691.
21.
Leick
,
M.
,
2010
, “
Optimizing Conventional Combustion and Implementing Low Temperature Combustion of Biodiesel in a Common-Rail High-Speed Direct-Injection Engine
,” M.S. thesis, Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL.
You do not currently have access to this content.