Experimental Study Of Effect Of Diesel Fuel Physical And Chemical Properties On Diesel Engine’s Performance

The physical and chemical properties of diesel fuel have important effects on diesel engine’s power output,fuel economy and emissions.Even though the diesel engine technology has underwent rapid development in recent years,however,diesel fuel quality still plays a key role in improving diesel engine’s performance and meeting emission regulations.Meanwhile,due to the inconsistency between fuel economy and emission regulations and imbalance among region’s development,“Oil and Vehicle” matching problem still stands out in China.Based on this,this paper conducted experimental study concerning the effects of diesel fuel properties on diesel engine’s power output,fuel economy and emission characteristics.Experiments were carried out on a heavy duty diesel engine equipped with electronically controlled high pressure common rail system,which can meet the State IV emission regulation.Firstly,the effects of fuel cetane number on diesel engine’s performance were explored.Results show that,prolonged ignition delay can be obtained as cetane number decreases at part load,thus retarded combustion phasing,increased maximum in-cylinder pressure and peak heat release rate were observed.With the increase of engine load,the effects of cetane number on combustion become weak.Due to the low volumetric calorific value of high cetane number fuels,less total fuel energy was injected into the cylinder with the same injection duration at high loads,resulted in lower power output as the fuel’s cetane number increases.The ESC test results show that,the fuel consumption,NOX,soot,HC and CO emissions can be reduced by 6%,14%,76%,70% and 60% respectively as the fuel’s cetane number increased from 27.3 to 61.8.Secondly,experiments have been conducted to study the effects of diesel fuel’s volatility(distillation temperature)on diesel engine’s performance and emissions.Much longer ignition delay can be observed as the distillation temperature decreases(higher volatility)at part load,resulted in retarded combustion phasing and increased BSFC.The effects of fuel properties on in-cylinder combustion process become weaker,and the BSFC difference between fuels with different distillation temperature gradually diminish,as the engine load increases.Higher engine’s power output can be obtained with the increase of distillation temperature.The ESC test results show that,fuel’s distillation temperature has significant impact on HC and CO emissions,while limited influence on fuel consumption,NOX and soot emissions were observed.From fuel No.1 to 8,the BSFC,HC and CO emissions can be reduced by 1.9%,66% and 47% respectively,while the variation range of NOX and soot emissions can be controlled within 6% and 60% with the increase of distillation temperature.Lastly,experimental study on the effects of fuels with different standards on engine’s performance was conducted.Results showed that,even though all these fuels were bought from commercially available gas stations,they still have great influence on engine’s fuel economy and emissions.Four standard fuel(state II-state V)samples were formulated to further explore their effects on engine performance,and the results showed that,these fuels have limited effects on engine’s performance,and the differences in power out was limited within 2.4%.The weighted ESC test results indicate that the difference in NOX,HC and CO emissions were limited within 7%,16% and 16% respectively,and no much difference can be observed due to the overall low soot emissions among tested fuels.