Effect of mixing chamber venturi, injection timing, compression ratio and EGR on the performance of dual-fuel engine operated with HOME and CNG

Abstract

Stringent environmental policies and the ever increasing demand for energy have triggered interest in novel combustion technologies that use alternative fuels as energy sources. Of these, pilot-ignited compressed natural gas (CNG) engines that employ small biodiesel pilot to ignite a premixed natural gas–air mixture have received considerable attention. This paper discusses the effect of mixing chamber venturi, injection timing, compression ratio and exhaust gas recirculation (EGR) on the performance of dual-fuel engine operated on biodiesel derived from honge oil and is called honge oil methyl ester (HOME) and CNG. The proposed study mainly focuses on the manifold induction of CNG along with HOME injection. However, CNG can also be injected using port or direct gas injector (Lakshmanan and Nagarajan 2010, Energy 35, pp. 3172–3178). The future study will involve these methods of CNG injection. From this study, it is concluded that an advanced injection timing and an increased compression ratio resulted in increased brake thermal efficiency and reduced smoke, hydrocarbons and carbon monoxide emissions. However, nitrogen oxides (NO x ) emission increased significantly. The increased NO x emission was effectively reduced with EGR method. A mixing chamber venturi of 3 mm size, injection timing of 27° before top dead centre (BTDC), compression ratio of 17.5 and 10% EGR were found to be optimum for the modified compression ignition engine that was operated on CNG–HOME dual-fuel mode.