Emission Reduction Operating Parameters for a Dual-Fuel Diesel Engine Run on Biogas and Rice-Bran Biodiesel

Biogas has great potential as a clean alternative fuel for dual-fuel diesel engines. The present work is aimed at investigating the operating parameters such as compression ratio (CR) and injection timing (IT) for a dual-fuel diesel engine run on biogas and rice-bran biodiesel. The motivation behind this investigation is to obtain a diesel equivalent performance together with a reduction in emission. To achieve this, a single-cylinder, direct-injection, variable-compression-ratio diesel engine is modified into a dual-fuel diesel engine by incorporating a venturi gas mixer at the inlet manifold. A set of combinations composed of CRs of 17, 17.5, and 18 and ITs of 23 degrees, 26 degrees, 29 degrees, and 32 degrees before top dead center (BTDC) at different loading conditions are considered. The combination of IT=32 degrees BTDC and CR=18 is found to produce a maximum brake thermal efficiency of 25.88% and a liquid fuel replacement of 82.75% at 100% load. On average, there is a reduction of carbon monoxide as well as hydrocarbon emissions by 11.64 and 14.21%, respectively. On the other hand, for the same setting, there is an increase of oxides of nitrogen emissions by 39%.