COMPARATIVE EXPERIMENTAL INVESTIGATION ON DI DIESEL ENGINE USING ALTERNATIVE FUEL

Thermal Engineering

The present investigation is aimed to examine the performance and emissions of a single cylinder, four stroke, direct injection diesel engine developing 4.4 kW at a rated speed of 1500 rpm, at optimum injection timing and optimum injection pressure of 230 bar, with lower compression ratios of 17:1 and 16:1, fueled with UTO by varying the clearance volume. At lower compression ratio, the engine exhibits a lower thermal efficiency and more smoke level. The engine behavior was also tested at higher compression ratio of 18.5:1. The effect of compression ratio on emission parameters of the engine fueled with UTO in comparison with diesel fuel operation is obtained. The optimum compression ratio was found to be 18.5:1. The results indicated that at higher compression ratio, there was an increase in brake thermal efficiency, NO emission and reduction in smoke. At this CR, the NO emission was found to be increased by about 2.8% and 32.1% respectively than that of the UTO and diesel. The smoke emission was found to decreased by about 3.6% and 10.4% respectively compared to that of UTO and diesel at full load. Further, the engine fueled with UTO was subjected to operate with optimum injection timing and optimum fuel nozzle opening pressure at different compression ratio (two lower and one higher CRs). The results were compared with diesel operation. A comparison was made between the results obtained from these investigations (i.e. operating the engine fueled with UTO at different compression ratio only with optimum injection timing and, optimum injection timing and optimum nozzle opening pressure). With optimum injection timing and optimum nozzle opening pressure, there was 3.25% and 2.14% increase in brake thermal efficiency and NO emission and 6.52% reduction in smoke at higher CR. At CR 17:1 the results are closer to diesel operation with optimum injection timing and optimum nozzle opening pressure.

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