Combustion, performance and emission characteristics of a DI diesel engine fuelled with non-petroleum fuel: A study on the role of fuel injection timing

Earlier investigations by the authors revealed that a blend of 80% Jatropha methyl ester (JME) and 20% Tyre pyrolysis oil (TPO) referred to as JMETPO20 blend exhibited a better performance and lower emissions compared to other JMETPO blends [1]. Being a fuel derived from a non-petroleum source, the original injection timing of diesel engine may not be suitable for the blend. In this study, the influence of the injection timing on the combustion, performance and emission characteristics of a single cylinder, four stroke, air cooled, constant speed, direct injection (DI), naturally aspirated diesel engine has been experimentally investigated, when the engine was run with the JMETPO20 blend. The original injection timing was altered by adjusting the number of shims fitted under the plunger in the pump, by addition or removal of shims. In addition to the original injection timing of 23 °CA bTDC, other injection timings at which the study was carriedout were 20, 21.5, 24.5 and 26 °CA bTDC. The results indicated that the blend gave a better performance and lower emissions when operated with an advanced injection timing of 24.5 °CA bTDC as compared to other injection timings. At the advanced injection timing of 24.5 °CA bTDC, the maximum cylinder pressure was found to be higher by about 2.7 bar with a longer ignition delay, than that in case of the original injection timing at brake mean effective pressure (BMEP) of 5.6 bar. Further, the brake specific energy consumption (BSEC) decreased by about 7.1% compared to that of the original injection timing at BMEP of 5.6 bar. The carbon monoxide (CO), hydrocarbon (HC) and particulate emissions were also found to be reduced by about 14.2%, 13.26% and 9.3% respectively.