Fueling a compression-ignition engine with premixed natural gas offers the potential to combine a clean-burning, low-carbon fuel with a high compression ratio, high-efficiency engine. This work describes the development of a multi-cylinder 6.7 L diesel engine converted to run stoichiometric diesel micro-pilot/ natural gas premix combustion with a maximum diesel contribution target of 5% of the total fuel energy and a three-way catalyst aftertreatment system. Results are given by comparing the stoichiometric combustion to the diesel baseline operation, showing combustion characteristics differences, including the rapid two stage heat release. A high load output of 23 bar brake mean effective pressure was obtained with diesel-like brake thermal efficiency of 41%. This operating condition enabled a brake specific CO2 emissions reduction of up to 25% when compared to diesel. It was observed that the low load output is limited by combustion stability when operated at stoichiometric condition. The three-way catalyst is observed to run at peak efficiency with an equivalence ratio of 1.01. Injector fouling was observed through the inspection of the nozzle and its internal parts, indicating carbon build-up similar to that seen in injector coking mechanisms. A comparison of the developed engine to other engine technologies is given, showing that the diesel micro-pilot natural gas engine performance is in good standing among other diesel and gas engines in the market.
MannsHJBrauerMDyjaHBeierHLaschA. Diesel CNG - the potential of a dual fuel combustion concept for lower CO2 and emissions. SAE paper 2015-26-0048, 2015.
4.
NaberJDSiebersDLDi JulioSSWestbrookCK. Effects of natural gas composition on ignition delay under diesel conditions. Combust Flame1994; 99: 192–200.
5.
KarimGA. Combustion in gas fueled compression ignition engines of the dual fuel type. J Eng Gas Turbine Power2003; 125: 827–836.
6.
ZhengJWangJZhaoZWangDHuangZ. Effect of equivalence ratio on combustion and emissions of a dual-fuel natural gas engine ignited with Diesel. Appl Therm Eng2019; 146: 738–751.
7.
YousefiABiroukMGuoH. An experimental and numerical study of the effect of diesel injection timing on natural gas/diesel dual-fuel combustion at low load. Fuel2017; 203: 642–657.
8.
ValladolidPGTunestalP. Effects of intake manifold conditions on dual-fuel CNG-diesel combustion in a light duty diesel engine operated at low loads. SAE paper 2016-01-0805, 2016.
9.
PapagiannakisRGHountalasDT. Combustion and exhaust emission characteristics of a dual fuel compression ignition engine operated with pilot diesel fuel and natural gas. Energy Convers Manag2004; 45: 2971–2987.
10.
KarimG. Combustion in gas-fuelled compression ignition engines. In: ASME ICE fall technical conference 2000, Chicago, IL, 23 September 2000, vol. 351, pp.35–31.
11.
WeaverCSTurnerSH. Dual fuel natural gas/diesel engines: technology, performance, and emissions. SAE paper 940548, 1994.
12.
VávraJBortelITakátsMDivišM. Emissions and performance of diesel–natural gas dual-fuel engine operated with stoichiometric mixture. Fuel2017; 208: 722–733.
13.
TaniguchiSMasubuchiMKitanoK, et al. Feasibility study of exhaust emissions in a natural gas diesel dual fuel (DDF) engine. SAE paper 2012-01-1649, 2012.
14.
WangZZhaoZWangD, et al. Impact of pilot diesel ignition mode on combustion and emissions characteristics of a diesel/natural gas dual fuel heavy-duty engine. Fuel2016; 167: 248–256.
15.
DronniouNKashdanJLecointeBSauveKSoleriD. Optical investigation of dual-fuel CNG/diesel combustion strategies to reduce CO2 emissions. SAE Int J Engines2014; 7: 873–887.
16.
AzimovUTomitaEKawaharaN. Ignition, combustion and exhaust emission characteristics of micro-pilot ignited dual-fuel engine operated under PREMIER combustion mode. SAE paper 2011-01-1764, 2011.
17.
McTaggart-CowanGPJonesHLRogakSNBusheWKHillPGMunshiSR. The effects of high-pressure injection on a compression-ignition, direct injection of natural gas engine. In: Proceedings of the ASME 2005 internal combustion engine division fall technical conference. ASME 2005 internal combustion engine division fall technical conference (ICEF2005), Ottawa, ON, Canada, 11–14 September 2005. pp.161–173.
18.
YouJLiuZWangZWangDXuY. Experimental Analysis of inert gases in EGR on engine power and combustion characteristics in a stoichiometric dual fuel heavy-duty natural gas engine ignited with Diesel. Appl Therm Eng2020; 180: 115860.
19.
WangZDingHMaXXuHWyszynskiML. Ultra-high speed imaging study of the diesel spray close to the injector tip at the initial opening stage with single injection. Appl Energy2016; 165: 335–344.
20.
YangXBonfochi VinhaesVTurciosM, et al. Process for study of micro-pilot diesel-NG dual fuel combustion in a constant volume combustion vessel utilizing the premixed pre-burn procedure. SAE paper 2019-01-1160, 2019.
21.
ZirngiblSWachtmeisterG. Extensive investigation of a common rail diesel injector regarding injection characteristics and the resulting influences on the dual fuel pilot injection combustion process. SAE paper 2016-01-0780, 2016.
LiuJDumitrescuCE. Analysis of two-stage natural-gas lean combustion inside a diesel geometry. Appl Therm Eng2019; 160: 114116.
24.
LiuJDumitrescuCE. Flame development analysis in a diesel optical engine converted to spark ignition natural gas operation. Appl Energy2018; 230: 1205–1217.
25.
SztenderowiczMLHeywoodJB. Cycle-to-cycle IMEP fluctuations in a stoichiometrically-fueled SI engine at low speed and load. SAE Int1990; 99: 2291–2309.
26.
Bonfochi VinhaesVYangXMcTaggart-CowanG, et al. Multi-variable sensitivity analysis and ranking of control factors impact in a stoichiometric micro-pilot natural gas engine at medium loads. SAE paper 2022-01-0463, 2022.
27.
SmithIChiuJBartleyG, et al. Achieving fast catalyst light-off from a heavy-duty stoichiometric natural gas engine capable of 0.02 g/bhp-hr NOX emissions. SAE paper 2018-01-1136, 2018.
28.
WilliamsRSmithAButteryI. Formation and removal of injector nozzle deposits in modern diesel cars. SAE Int J Fuel Lubricants2013; 6: 230–240.
29.
CaprottiRBhattiNBalfourG. Deposit control in modern diesel fuel injection systems. SAE Int J Fuel Lubricants2010; 3: 901–915.
30.
NaberJBloughJRFrankowskiD, et al. Analysis of combustion knock metrics in spark-ignition engines. SAE paper 2006-01-0400, 2006.
31.
Bonfochi VinhaesVMcTaggart-CowanGMunshiSShahbakhtiMNaberJD. Experimental studies of low-load limit in a stoichiometric micro-pilot diesel natural gas engine. Energies2022; 15: 728.
32.
MitchellRKocsisM. Performance evaluation of dedicated EGR on a 12 L natural gas engine. SAE paper 20190-01-1143, 2019.
33.
JoshiSDahodwalaMKoehlerEW, et al. Trade-off analysis and systematic optimization of a heavy-duty diesel hybrid powertrain. SAE paper 2020-01-0847, 2020.
34.
DimitriouPJavaidR. A review of ammonia as a compression ignition engine fuel. Int J Hydrogen Energy2020; 45: 7098–7118.
35.
DimitriouPTsujimuraT. A review of hydrogen as a compression ignition engine fuel. Int J Hydrogen Energy2017; 42: 24470–24486.
