Experimental Investigations to Improve the Performance of Rubber Seed Oil–Fueled Diesel Engine by Dual Fueling with Hydrogen

Abstract

In this experimental work, base data were generated with diesel and neat high free fatty acid (FFA) rubber seed oil (RSO) using a single-cylinder air-cooled diesel engine with a rated output of 4.4 kW at 1500 rpm. Neat RSO results in reduced thermal efficiency of 26.6% compared with diesel efficiency of 29.9% and high smoke emissions compared to diesel. This is mainly due to low volatility, higher viscosity, and density of RSO. In order to improve the performance of the RSO-fueled diesel engine, experiments were conducted with hydrogen as the inducted fuel and RSO as the main fuel in dual-fuel operation. Experimental results indicate that the brake thermal efficiency increases from 75% load to full load in the dual-fuel operation. At full load, the maximum brake thermal efficiency is 28.1% with RSO-hydrogen dual-fuel mode at hydrogen energy share of 8.39%. The smoke level is reduced at all loads with RSO-hydrogen dual-fuel mode. The smoke level is reduced from 6.1 to 3.8 BSU in dual-fuel operation at the maximum efficiency point at full load. Hydrogen induction reduces HC and CO at all loads, but NOx increases at 75% and full load, but there is no appreciable change at lower loads. The combustion duration decreases with hydrogen addition. This will also contribute to higher heat release rate in the premixed combustion phase. The cylinder peak pressure and maximum rate of pressure rise increases mainly at higher outputs. On the whole it is concluded that hydrogen can be inducted along with air in order to reduce smoke levels and improve thermal efficiency of rubber seed oil–fueled diesel engines for loads above part load.