The effect of operating parameters on performance and emissions of DI diesel engine fuelled with Jatropha biodiesel

Abstract

In the present investigation the combustion, performance and emission analysis of a small Direct Injection diesel engine was done in order to find the effect of Jatropha Methyl Ester as a fuel on the engine. In this study, speed, load and fuel injection timing were varied according to (3 × 3 × 3) full factorial design and cylinder pressure, fuel consumption, smoke and emissions of HC and NOx were measured. For understanding the nature of cylinder pressure rise and combustion characteristics of Jatropha Methyl Ester and diesel fuel, the cylinder pressures were recorded for all the combinations of load, speed and injection timing. Comparative study of engine emissions and fuel economy was carried between Jatropha Methyl Ester and Diesel. The response surface quadratic models were generated for the four output parameters viz. smoke, brake specific fuel consumption, unburned hydrocarbons and NOx relative to the three input parameters: speed, load and injection timing. The response surface equations were then solved as multi-objective nonlinear constrained optimization problem using the Design-Expert 10.0 software, which makes use of the desirability functions. Further, optimization was done to search the optimum combinations of load, speed, and injection timing which give the possible minimum emissions, well lower than the set values. The maximum rate of heat release was found to be higher for diesel than that of JME at all the speeds, loads and injection timings combinations. The maximum reduction of 72.56% in smoke level was observed at 12°CA btdc, 70% load and at 3100 rpm when JME was used as fuel. Maximum increase of 30% in NOx emission was found at 15° crank angle, 70% load and 2300 rpm when JME was used as fuel. Response surface methodology (RSM) was found to be a useful technique for modeling engine responses using three input parameters viz. speed, load and injection timing.