A Computational Investigation of Piston Bowl Geometry and Injector Spray Pattern Effects on Gasoline Compression Ignition in a Heavy-Duty Diesel Engine

Abstract This study computationally investigates the potential of utilizing gasoline compression ignition (GCI) in a heavy-duty diesel engine to address a future ultra-low tailpipe NOx standard of 0.027 g/kWh while achieving high fuel efficiency. By conducting closed-cycle, full-geometry, 3-D computational fluid dynamics (CFD) combustion simulations, the effects of piston bowl geometry, injector spray pattern, and swirl ratio (SR) were investigated for a market gasoline. The simulations were performed at 1375 rpm over a load range from 5 to 15 bar BMEP. The engine compression ratio (CR) was increased from 15.7 used in previous work to 16.5 for this study. Two piston bowl concepts were studied with Design 1 attained by simply scaling from the baseline 15.7 CR piston bowl, and Design 2 exploring a wider and shallower combustion chamber design. The simulation results predicted that through a combination of the wider and shallower piston bowl design, a 14-hole injector spray pattern, and a swirl ratio of 1, Design 2 would lead to a 2–7% indicated specific fuel consumption (ISFC) improvement over the baseline by reducing the spray-wall interactions and lowering the in-cylinder heat transfer loss. Design 1 (10-hole and SR2) showed a more moderate ISFC reduction of 1–4% by increasing CR and the number of nozzle holes. The predicted fuel efficiency benefit of Design 2 was found to be more pronounced at low to medium loads.

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Piston Bowl Geometry Effects on Gasoline Compression Ignition in a Heavy-Duty Diesel Engine

10.1115/1.0003738v ◽

2021 ◽

Author(s):

Meng Tang ◽

Yuanjiang Pei ◽

Hengjie Guo ◽

Yu Zhang ◽

Roberto Torelli ◽

...

Keyword(s):

Diesel Engine ◽

Compression Ignition ◽

Heavy Duty ◽

Piston Bowl ◽

Heavy Duty Diesel Engine ◽

Geometry Effects ◽

Heavy Duty Diesel

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A Computational Investigation of Fuel Chemical and Physical Properties Effects on Gasoline Compression Ignition in a Heavy-Duty Diesel Engine

Volume 1: Large Bore Engines; Fuels; Advanced Combustion ◽

10.1115/icef2017-3664 ◽

2017 ◽

Cited By ~ 1

Author(s):

Yu Zhang ◽

Alexander Voice ◽

Yuanjiang Pei ◽

Michael Traver ◽

David Cleary

Keyword(s):

Diesel Engine ◽

Physical Properties ◽

Ignition Delay ◽

Fuel Efficiency ◽

Air Entrainment ◽

Compression Ignition ◽

Heavy Duty ◽

Heavy Duty Diesel Engine ◽

Air Mixing ◽

Heavy Duty Diesel

Gasoline compression ignition (GCI) offers the potential to reduce criteria pollutants while achieving high fuel efficiency in heavy-duty diesel engines. This study aims to investigate the fuel chemical and physical properties effects on GCI operation in a heavy-duty diesel engine through closed-cycle, 3-D computational fluid dynamics (CFD) combustion simulations, investigating both mixing-controlled combustion (MCC) at 18.9 compression ratio (CR) and partially premixed combustion (PPC) at 17.3 CR. For this work, fuel chemical properties were studied in terms of the primary reference fuel (PRF) number (0–91) and the octane sensitivity (0–6) while using a fixed fuel physical surrogate. For the fuel physical properties effects investigation, PRF70 was used as the gas-phase chemical surrogate. Six physical properties were individually perturbed, varying from the gasoline to the diesel range. Combustion simulations were carried out at 1375 RPM and 10 bar brake mean effective pressure (BMEP). Reducing fuel reactivity (or increasing PRF number) was found to influence ignition delay time (IDT) more significantly for PPC than for MCC due to the lower charge temperature and higher EGR rate involved in the PPC mode. 0-D IDT calculations suggested that the fuel reactivity impact on IDT diminished with an increase in temperature. Moreover, higher reactivity gasolines exhibited stronger negative coefficient (NTC) behavior and their IDTs showed less sensitivity to temperature change. When exploring the octane sensitivity effect, ignition was found to occur in temperature conditions more relevant to the MON test. Therefore, increasing octane sensitivity (reducing MON) led to higher reactivity and shorter ignition delay. Under both MCC (TIVC: 385K) and PPC (TIVC: 353K), all six physical properties showed little meaningful impact on global combustion behavior, NOx and fuel efficiency. Among the physical properties investigated, only density showed a notable effect on soot emissions. Increasing density resulted in higher soot due to deteriorated air entrainment into the spray and the slower fuel-air mixing process. When further reducing the IVC temperature from 353K to 303K under PPC, the spray vaporization and fuel-air mixing were markedly slowed. Consequently, increasing the liquid fuel density created a more pronounced presence of fuel-rich and higher reactivity regions, thereby leading to an earlier onset of hot ignition and higher soot.

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A Computational Investigation of Fuel Chemical and Physical Properties Effects on Gasoline Compression Ignition in a Heavy-Duty Diesel Engine

Journal of Energy Resources Technology ◽

10.1115/1.4040010 ◽

2018 ◽

Vol 140 (10) ◽

Cited By ~ 4

Author(s):

Yu Zhang ◽

Alexander Voice ◽

Yuanjiang Pei ◽

Michael Traver ◽

David Cleary

Keyword(s):

Diesel Engine ◽

Physical Properties ◽

Fluid Dynamic ◽

Fuel Efficiency ◽

Chemical Properties ◽

Air Entrainment ◽

Compression Ignition ◽

Heavy Duty ◽

Heavy Duty Diesel Engine ◽

Heavy Duty Diesel

Gasoline compression ignition (GCI) offers the potential to reduce criteria pollutants while achieving high fuel efficiency. This study aims to investigate the fuel chemical and physical properties effects on GCI operation in a heavy-duty diesel engine through closed-cycle, three-dimensional (3D) computational fluid dynamic (CFD) combustion simulations, investigating both mixing-controlled combustion (MCC) at 18.9 compression ratio (CR) and partially premixed combustion (PPC) at 17.3 CR. For this work, fuel chemical properties were studied in terms of the primary reference fuel (PRF) number (0–91) and the octane sensitivity (0–6) while using a fixed fuel physical surrogate. For the fuel physical properties effects investigation, six physical properties were individually perturbed, varying from the gasoline to the diesel range. Combustion simulations were carried out at 1375 RPM and 10 bar brake specific mean pressure (BMEP). Reducing fuel reactivity was found to influence ignition delay time (IDT) more significantly for PPC than for MCC. 0D IDT calculations suggested that the fuel reactivity impact on IDT diminished with an increase in temperature. Moreover, higher reactivity gasolines exhibited stronger negative coefficient (NTC) behavior and their IDTs showed less sensitivity to temperature change. In addition, increasing octane sensitivity was observed to result in higher fuel reactivity and shorter IDT. Under both MCC and PPC, all six physical properties showed little impact on global combustion behavior, NOx, and fuel efficiency. Among the physical properties investigated, only density showed a notable effect on soot emissions. Increasing density led to higher soot due to deteriorated air entrainment into the spray and the slower fuel-air mixing process.

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