Effect of Variable Valve Timing on Diesel Combustion Characteristics

Ojeda, William De

doi:10.4271/2010-01-1124

Cited by 42 publications

(24 citation statements)

References 13 publications

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“…Similar trends in emissions responses to early inlet valve closure were reported in Ref. [5], for a heavy duty V8 diesel engine. This similarity of responses to both EIVC and LIVC timing changes is evident in other work [6e13], with some exceptions which may be attributable to the varying range of MAP (manifold absolute pressure), AFR (air to fuel ratio) and EGR rate settings examined in the different investigations.…”

Section: Introductionsupporting

confidence: 78%

The effects of early inlet valve closing and cylinder disablement on fuel economy and emissions of a direct injection diesel engine

Zammit

McGhee

Shayler

et al. 2015

Energy

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a b s t r a c tThe influence of EIVC (early inlet valve closure) on emissions, fuel economy and exhaust gas temperature of a turbocharged, 4 cylinder common rail direct injection diesel engine has been investigated and compared with the influence of deactivating two cylinders. IVC (inlet valve closing) timings were set at up to 60 CA (crank angle) degrees earlier than the production setting of 37 ABDC for the engine. At the earliest timing, effective compression ratio was reduced from 15.2:1 to 13.7:1. The effects on emissions were significant only for EIVC settings at least 40 CA degrees earlier than the production setting, and were sensitive to engine load. At 2 bar BMEP (brake mean effective pressure) and fixed levels of NO x , soot emissions were reduced but CO (carbon monoxide) and HC (hydrocarbon) increased unless fuel rail pressure was reduced. With increasing load, soot reduction diminished and was negligible at 6 bar BMEP; CO and HC emissions deteriorated further. At all conditions, EIVC raised exhaust gas temperature by >50 C; the effect on fuel economy was negligible or a fuel economy penalty. Comparisons indicate cylinder deactivation is the more effective strategy for reducing engine-out emissions of HC and CO and raising exhaust gas temperature under light load operating conditions.

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Section: Introductionsupporting

confidence: 78%

The effects of early inlet valve closing and cylinder disablement on fuel economy and emissions of a direct injection diesel engine

Zammit

McGhee

Shayler

et al. 2015

Energy

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“…[22][23][24] Other research into the use of a VVA to improve exhaust thermal management can be found in literatures. [25][26][27] The focus of this work is the exploration and direct comparison of different strategies for EGT management and the trade-off with fuel efficiency and emissions. Conventional strategies regarding air and fuel paths such as retarded injection timings, lower diesel injection pressures, intake throttling, as well as external EGR (eEGR), will be investigated here as the baseline results and for comparison with VVA strategies including LIVC and iEGR.…”

Section: Introductionmentioning

confidence: 99%

Exploring alternative combustion control strategies for low-load exhaust gas temperature management of a heavy-duty diesel engine

Guan

Zhao

Ban

et al. 2018

International Journal of Engine Research

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6The employment of aftertreatment systems in modern diesel engines has become indispensable 7 in order to meet the stringent emissions regulations. However, a minimum exhaust gas 8 temperature (EGT) of approximately 200°C must be reached to initiate the emissions control 9 operations. Low load engine operations usually result in relatively low EGT, which lead to 10 reduced or no exhaust emissions conversion. In this context, this study investigated the use of 11 different combustion control strategies to explore the trade-off between EGT, fuel efficiency 12 and exhaust emissions. 13 14The experiments were carried out on a single cylinder common rail heavy-duty diesel engine 15 at a light load of 2.2 bar indicated mean effective pressure. Strategies include the late intake 16 valve closure (LIVC) timing, intake throttling, late injection timing (Tinj), lower injection 17 pressure (Pinj), and internal exhaust gas recirculation (iEGR) as well as external EGR (eEGR) 18 were investigated. Results showed that the use of eEGR and lower Pinj were not effective in 19 increasing EGT. Although the use of late Tinj could result in a higher EGT, the delayed 20 combustion phase led to the highest fuel efficiency penalty. Intake throttling and iEGR allowed 21 for an increase in EGT by 42°C and 52°C at the expense of 7.2% and 17% fuel consumption 22 penalties, respectively. In comparison, LIVC strategy achieved the best trade-off between EGT 23 and ISFC, increasing the EGT by 52°C and the fuel consumption penalty by 5.3% while 24 reducing NOx and soot emissions simultaneously. When the IVC timing was delayed to after 25 -107 CAD ATDC, however, the combustion efficiency deteriorated, and hence very high HC 26 and CO emissions. This could be overcome by combining iEGR with LIVC to increase the in-27 cylinder combustion temperature for a more complete combustion. The results demonstrated 28 that the "LIVC + iEGR" strategy can be the most effective means, increasing the EGT by 62°C 29 with small penalty in the fuel consumption of 4.6% and soot emission reduction by 85%. 30 Meanwhile, maintaining high combustion efficiency as well as low HC and CO emissions of 31 diesel engines. 32 Keywords 33 Heavy-duty diesel engine, variable valve actuation, late intake valve closing, internal EGR, 34 exhaust temperature, exhaust emissions 35 36 42 combustion produces a large amount of particulate matter (PM) in the fuel rich burning region 43 and high concentration of nitrogen oxide (NOx) in the high temperature zones [1]. In order to 44 meet the Euro VI or equivalent emission regulations of 0.4 g/kW•h NOx and 0.010 g/kW•h PM 45 [2], significant reduction of these pollutants by in-cylinder combustion technologies and 46 emission control aftertreatment systems are required. 47 48 Advanced combustion modes such as Homogeneous Charge Compression Ignition (HCCI), 49 Pre-mixed Charge Compression Ignition (PCCI), and Low Temperature Combustion (LTC) 50 are able to achieve a reduction in NOx and soot simultaneously, through reducing the peak in-51...

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“…In fact, VVA can also offer great benefits to diesel engines, as elaborated in Xin (2011). In the SuperTruck program, variable IVC timing has been researched as one possible way of improving engine thermal efficiency to achieve flexible controls on engine compression ratio and low-temperature combustion timing (De Ojeda, 2010a, 2010b. In fact, the Miller cycle with early or late IVC timing has been always regarded as one of the very rare engine technologies that can simultaneously reduce no x and BSFC (Ke and Pucher, 1996;Clarke and Smith, 1997;Edwards et al, 1998;Millo et al, 2004;imperato et al, 2009;Yang et al, 2009Yang et al, , 2010Murata et al, 2010).…”

Section: Improving Conventional Valvetrains and The Use Of Variable Vmentioning

confidence: 99%

Improving the environmental performance of heavy-duty vehicles and engines: particular technologies

Xin

Pinzon

2014

Alternative Fuels and Advanced Vehicle Technologies for Improved Environmental Performance

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Effect of Variable Valve Timing on Diesel Combustion Characteristics

Cited by 42 publications

References 13 publications

The effects of early inlet valve closing and cylinder disablement on fuel economy and emissions of a direct injection diesel engine

The effects of early inlet valve closing and cylinder disablement on fuel economy and emissions of a direct injection diesel engine

Exploring alternative combustion control strategies for low-load exhaust gas temperature management of a heavy-duty diesel engine

Improving the environmental performance of heavy-duty vehicles and engines: particular technologies

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