Exergy Analysis and Optimization of Multiple Injection Parameters of a Diesel Engine with Taguchi Method

Abstract

Multiple injection parameters have a significant effect on performance and emission formation in diesel engines. This study presents the optimization of these parameters with Taguchi method for different engine operating conditions. The experiments were conducted using four injections per cycle named Pilot1 (P1), Pilot2 (P2), Main (M), and Post (Po). The input parameters considered were injection timings and fuel quantities for each injection, while the output parameters were brake specific fuel consumption (BSFC) and nitrogen oxides (NOx) emissions. According to the results, the analysis of variance (ANOVA) shows that the durations of the P2 (D_P2) and Po (D_Po) and the start of the Main (SOI M) injection are very significant on BSFC and NOx emissions as independent of the engine speed. Based on contribution ratios at 1750 rpm and 2250 rpm operating conditions, D_Po is the most effective parameter on BSFC with 47.28% and 51.30%, while D_P2 has the greatest impact on NOx emissions with 37.96% and 61.80%, respectively. It is found from the optimization model obtained by using the Signal/Noise (S/N) ratios that injecting 5% of the total fuel in the post-injection phase could simultaneously improve BSFC and NOx emissions. Furthermore, the optimization model generally reduces heat loss exergy, exhaust exergy, and exergy destruction compared to the experimental values.