Improve Combustion During Cold Start of DI Diesel Engine by EGR Under Normal Ambient Temperature

Peng, Haiyong; Cui, Yi; Shi, Lei; Deng, Kangyao

doi:10.4271/2008-01-1084

Cited by 14 publications

(8 citation statements)

References 8 publications

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“…26 Furthermore, investigations done to assess the potential of exhaust gas recirculation (EGR) revealed that incomplete combustion products in the exhaust gas, including unburned hydrocarbon and fuel vapour, are beneficial for improving the coldstart behaviour. 27 In addition to the approaches mentioned above, external cold-start assist technologies are often used to further improve diesel engines' cold-startability and idle stability. The external devices' primary purpose is to ensure that the required thermal energy is supplied to increase the in-cylinder charge temperature.…”

Section: Introductionmentioning

confidence: 99%

A novel strategy of extremely delayed intake valve opening to improve the cold-start characteristics of a low compression ratio diesel engine

Vikraman

Anand

Ramesh

2021

International Journal of Engine Research

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Combined in-cylinder and after-treatment emission control methods are generally adopted to meet the current stringent emission targets for diesel engines. It is well established that reducing the geometric compression ratio (CR) results in a simultaneous reduction in the oxides of nitrogen (NOx) and soot emissions in diesel engines. However, poor cold-start characteristics prevent extensive use of low compression ratio (LCR) diesel engines for automotive applications. In the present work, a novel extremely delayed intake valve opening (IVO) strategy is proposed to improve the cold-start characteristics of a light-duty LCR diesel engine. A commercial one-dimensional gas-exchange model was used to optimize the intake valve open and close timings. The results corresponding to a cranking speed of 200 rpm and ambient temperature of 0°C show that advancing the intake valve close (IVC) timing increases the effective compression stroke that can improve the cylinder temperature by 5%. Further, implementing ‘extremely delayed IVO’ by retarding the timing from 1°CA to 61°CA aTDC could help to further increase the cylinder temperature by 14% compared to the base timings. The delayed opening of the intake valve leads to a higher expansion of the cylinder mass, leading to a lower cylinder pressure before IVO and a higher intake air velocity immediately after IVO. With the higher intake air velocity, the incoming air’s kinetic energy is dissipated to increase the stagnation temperature, resulting in an overall benefit in cylinder temperature. The experimental measurements conducted in a cold chamber with the optimized IVO and IVC timings confirmed the benefits by achieving a better cold-startability of the LCR engine. In comparison, the LCR engine with the stock valve timings could be started only up to +5°C, the optimized valve timings could ensure startability up to −10°C without any starting aids. Thus, the proposed approach of adopting the optimized valve timings can help LCR diesel engines to overcome the limitations of cold-startability.

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Section: Introductionmentioning

confidence: 99%

A novel strategy of extremely delayed intake valve opening to improve the cold-start characteristics of a low compression ratio diesel engine

Vikraman

Anand

Ramesh

2021

International Journal of Engine Research

View full text Add to dashboard Cite

show abstract

“…14 The introduction of EGR can improve cold-starting since the exhaust gases include unburned hydrocarbon and fuel vapor which are typically the products of partial combustion. 25 The next big challenge with the LCR approach is the penalty in BSFC due to the limited expansion ratio of the high pressure burned gases leading to reduced work output. On the emissions front, the LCR approach in a diesel engine might result in elevated HC and CO emissions owing to lower in-cylinder temperatures.…”

Section: Introductionmentioning

confidence: 99%

Novel strategies to overcome the limitations of a low compression ratio light duty diesel engine

Vikraman

Anand

Ramesh

2020

International Journal of Engine Research

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Low compression ratio (LCR) approach in diesel engines can reduce the oxides of nitrogen (NOx) and soot emissions simultaneously owing to lower temperatures and longer fuel-air premixing time. The present work investigates the effects of lowering the geometric compression ratio (CR) from 18:1 to 14:1 in a naturally aspirated (NA) single cylinder common rail direct injection (CRDI) diesel engine. Based on the investigations done across the entire speed and load range, significant benefits were observed in the NOx and soot emissions. However, lowering the compression ratio had adverse effects on brake specific fuel consumption (BSFC), unburned hydrocarbon (HC) and carbon monoxide (CO) emissions, especially at low-load and high-speed operating points. To overcome these limitations, novel strategies including split-cooling system (SCS) and secondary exhaust valve opening (SEVO) are proposed in the present work. While the fuel injection parameters optimization specific to LCR could help to improve the BSFC, HC and CO emissions penalty to a reasonable extent, the SCS concept can provide further benefits by reducing the heat loss to coolant and improving the engine component temperatures. Increasing the residual gas fraction using the optimized SEVO concept could further improve the charge temperature leading to a further reduction in the BSFC, HC and CO emissions. The net benefits of the optimized LCR approach are quantified for the modified Indian drive cycle (MIDC) using a one-dimensional simulation tool. The results obtained show a signification reduction of 22% and 74% in NOx and soot emissions respectively as compared to the base 18 CR engine results. Moreover, the penalty in HC and CO emissions could be contained to a large extent resulting in only a slight penalty of 23% and 20% respectively. Furthermore, the higher BSFC with the LCR approach could be successfully addressed and the final values were found to be better than the stock compression ratio by 1.5%. Overall, the strategies proposed in the present work are found to be beneficial to develop modern diesel engines in compliance with the future emission regulations which demand extreme control on NOx and soot emissions.

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“…The CR of the direct injection Diesel engine is about 18-22, and it can even be reduced as low as 12 after adopting the high turbocharging technology [10,11]. Under normal temperature and running conditions, it has little effect on the working of Diesel engine, --------------but when the engine running in the extremely cold weather, the temperature at the end of compression stroke cannot reach the spontaneous combustion temperature of diesel fuel, which will cause the engine cannot start up and work normally [12,13]. Besides, the performance of the storage battery will reduce owing to the low temperature, which will cause the performance reducing of the start-up system [14,15].…”

Section: Introductionmentioning

confidence: 99%

Study on cold starting performance of a low compression ratio diesel engine by using intake flame preheating

Zhang

Liu

et al. 2020

THERM SCI

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Power density improvement is one the main techniques for engine thermal efficiency promotion. For turbocharged Diesel engine, low compression ratio in normally adopted for safety consideration under high power density operation. However, low compression ratio tends to lead cold starting problem. In this study, the influences factors and performances of a 10-cylinder turbocharged Diesel engine was investigated. An intake flame preheating model was built and validated by series of bench tests. The optimization of starting parameters and flame heating was conducted eventually. Based on the study, the basic performance flame pre-heating system under different conditions was disclosed. The cold starting boundary parameters of the Diesel engine was found. Moreover, the best starting fuel injection parameters were acquired. The research is beneficial for Diesel engine power density promotion based on cold starting ability

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Improve Combustion During Cold Start of DI Diesel Engine by EGR Under Normal Ambient Temperature

Cited by 14 publications

References 8 publications

A novel strategy of extremely delayed intake valve opening to improve the cold-start characteristics of a low compression ratio diesel engine

A novel strategy of extremely delayed intake valve opening to improve the cold-start characteristics of a low compression ratio diesel engine

Novel strategies to overcome the limitations of a low compression ratio light duty diesel engine

Study on cold starting performance of a low compression ratio diesel engine by using intake flame preheating

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