Maximum efficiencies for internal combustion engines: Thermodynamic limitations

Caton, Jerald A.

doi:10.1177/1468087417737700

Cited by 31 publications

(19 citation statements)

References 41 publications

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“…17. Although increasing the specific heat ratio can increase the work extraction from the exhaust gases to some extent [35], exhaust energy recovery is more important for the further improvement of ITE [36]. The NOx emissions in all cases are excessively high due to the high combustion temperature, so EGR and/or after-treatment systems should be introduced.…”

Section: Effect Of Spark Timingmentioning

confidence: 99%

Investigation on a high-stratified direct injection spark ignition (DISI) engine fueled with methanol under a high compression ratio

Bai

Tunér

et al. 2019

Applied Thermal Engineering

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This paper reports an investigation of a highly stratified methanol direct injection spark ignition (DISI) engine with a high compression ratio. The effects of the start of injection (SOI), spray-included angle, injection pressure, and spark timing (ST) on in-cylinder flow, fuel distribution, flame propagation, and engine performance are evaluated in detail. The combustion process of methanol DISI engine is very sensitive to the variation of SOI, which is closely associated with the in-cylinder turbulence and the fuel/air mixing. It is found that retarding SOI shows the similar effects on combustion process as reducing spray-included angle, which indicates that the effects of SOI are more related to the spray target (i.e., fuel distribution). The injection pressure affects the combustion process mainly through the impact on the fuel distribution in the cylinder. The flame propagates from the spark plug towards the cylinder axis along the in-cylinder swirl direction, and more fuel mass in the piston bowl promotes the flame propagation. Thus, more retarded SOI, smaller spray-included angle, and lower injection pressure are suggested at low loads to enrich the fuel concentration in the bowl to achieve a stable combustion. Under medium load, indicated thermal efficiency (ITE), peak pressure rise rate (PPRR), and nitrogen oxides (NOx) emissions can be improved with advanced SOI. ITE can also be improved by advancing ST with a slight penalty on PPRR and NOx. This study demonstrates the potential of simultaneously optimizing fuel injection and ST to improve engine performance.

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Section: Effect Of Spark Timingmentioning

confidence: 99%

Investigation on a high-stratified direct injection spark ignition (DISI) engine fueled with methanol under a high compression ratio

Bai

Tunér

et al. 2019

Applied Thermal Engineering

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“…Another advantage of heat loss reduction is increased potential of enhanced engine work output [7]. A previously proposed solution, to utilize reduced heat losses, is the double compression expansion engine (DCEE) [8].…”

Section: Introductionmentioning

confidence: 99%

Thermal Efficiency Comparison of Different Injector Constellations in a CI Engine

Nyrenstedt

Watanabe²,

Enya³

et al. 2019

SAE Technical Paper Series

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More stringent emission regulations call for high-efficiency engines in the heavy-duty vehicle sector. Towards this goal, reduced heat losses, as well as increased work output, are needed. In this study, a multiple injector concept to control the combustion as well as reduce the hot boundary zones is proposed. Earlier studies have proven that multiple injectors experience lower heat losses and higher efficiency. However, a comprehensive investigation of the causes for experimental heat loss was not performed in depth. Experiments in a heavy-duty CI engine equipped with three injectors were thus performed. Engine configurations of single, dual and triple injectors were compared for a single-injection case as well as a multi-injection (Sabathe-cycle) case. Heat losses, efficiency and the emission levels were quantified and investigated. Optical experiments were performed to investigate the temperature field as well as flame behavior. This led to further understanding of the heat loss drivers. Experimental data was coupled with the double compression expansion engine concept for waste heat recovery, utilizing the energy from reduced heat losses. Notable findings included an efficiency increase of 1.9 %-points when using all three injectors for a single injection. Three injectors improved the efficiency an additional 1.2 %-points in a Sabathe-cycle case as compared to a single injector case. These gains mainly followed by reduced heat losses caused by hot zones being kept away from the boundaries. Thus, the benefits of multiple injectors were proven.

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“…One-zone models allow conducting the thermodynamic analysis of the ICE cycle [23], determining specific fuel consumption, torque, power, thermal efficiency [24] and power balance [25]. But there are still unresolved issues related to modeling the processes in the cylinder in the mixture formation and combustion zones, which limits the completeness of the description and understanding of these processes.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Development of a three-zone combustion model for stratified-charge spark-ignition engine

Korohodskyi

Rogovyi

Voronkov

et al. 2021

EEJET

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A thermodynamic model for calculating the operating process in the cylinder of a spark-ignition engine with internal mixture formation and stratified air-fuel charge based on the volume balance method was developed. The model takes into account the change in the working fluid volume during the piston movement in the cylinder. The equation of volume balance of internal mixture formation processes during direct fuel injection into the engine cylinder was compiled. The equation takes into account the adiabatic change in the volume of the stratified air-fuel charge, consisting of fuel-air mixture volume and air volume. From the heat balance equation, the change in the fuel-air mixture volume during gasoline evaporation in the fuel stream and from the surface of the fuel film due to external heat transfer was determined. Basic equations of combustion-expansion processes of the stratified air-fuel charge were derived, taking into account three zones corresponding to combustion products, fuel-air mixture and air volumes. The equation takes into account the change in the working fluid volume due to heat transfer and heat exchange between the zones and the walls of the above-piston volume. Dependences for determining the temperature in the three considered zones and pressure in the cylinder were obtained. Graphs of changes in the volumes of the combustion products, fuel-air mixture and air zones with the change of the above-piston volume in partial load modes (n=3,000 rpm) were plotted. With increasing load from bmep=0.144 MPa to bmep=0.322 MPa, at the moment of fuel ignition, the volume of the fuel-air mixture increases from 70 % to 92 % of the above-piston volume. At the same time, the air volume decreases from 30 % to 8 %. Analysis of theoretical and experimental indicator diagrams showed that discrepancies in the maximum combustion pressure do not exceed 5 %

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Maximum efficiencies for internal combustion engines: Thermodynamic limitations

Cited by 31 publications

References 41 publications

Investigation on a high-stratified direct injection spark ignition (DISI) engine fueled with methanol under a high compression ratio

Investigation on a high-stratified direct injection spark ignition (DISI) engine fueled with methanol under a high compression ratio

Thermal Efficiency Comparison of Different Injector Constellations in a CI Engine

Development of a three-zone combustion model for stratified-charge spark-ignition engine

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