ENHANCING PERFORMANCE OF BIODIESEL-HYDROGEN BLENDS OPERATED DI DIESEL ENGINE USING VARIABLE INJECTION TIMING

Abstract

The study aimed to investigate the effect of injection timing (IT) on the combustion, emission, and performance characteristics of a single-cylinder, four-stroke, direct injection (DI) diesel engine. The engine was run on different fuel blends, namely, pure diesel, diesel blended with 20% mahua oil methyl ester (B20) with three hydrogen flow rates of 20, 22.5, and 25 liters per minute (lpm). The experiment was carried out at a rated speed of 2000 rpm. Four different injection timings (ITs) were applied, namely, 19°, 23°, 27°, and 31° bottom top dead center (BTDC), relative to the standard IT of 23° BTDC. The results showed that the optimal IT was 27° BTDC for B20-hydrogen (22.5 lpm) dual-fuel mode operation. This condition delivered the highest brake thermal efficiency (BTE) between 24.4 and 34.3% , the lowest brake-specific fuel consumption (BSFC) between 0.25 and 0.41 kg/KWh, and the minimum unburnt hydrocarbon (HC) emissions between 8 and 32 ppm, and carbon-monoxide (CO) emissions ranging between 0.002 and 0.389% . However, the concentration of nitrogen-oxides (NOx) emissions was slightly increased, ranging between 24 and 53 ppm compared to B20. Further modifications in the IT resulted in decreased brake thermal efficiency ranging between 13 and 31% , increased hydrocarbon emissions between 25 and 28% , and increased CO emissions between 70 and 96% for both 4° BTDC advancements and retardations. Moreover, both modifications reduced NOx emissions by 8-19% . Hence, based on this study's findings, employing an IT of 27° BTDC for 22.5 Ipm of hydrogen with a B20 dual-fuel mode of operation for the DI diesel engine to achieve optimal performance, combustion, and emission characteristics is recommended.