Theoretical Performance Limits of a Biogas-Diesel Powered Dual Fuel Diesel Engine for Different Combinations of Compression Ratio and Injection Timing

The present work attempts to investigate the effect of compression ratio (CR) and injection timing (IT) on the energy and the exergy potential of a biogas-run dual fuel diesel engine. For experimentation, a 3.5 kW single cylinder, four-stroke, direct injection, naturally aspirated, water cooled, variable compression ratio diesel engine is converted into a dual fuel engine. Experiments are conducted for 16 different combinations comprising of ITs of 23, 26, 29, and 32 degrees before top dead center (BTDC) and CRs of 18, 17.5, 17, and 16 at full load condition of 4.24 bar of brake mean effective pressure. The parameters analyzed are the energy and exergy potential of fuel input, shaft work, cooling water, exhaust gas, exergy destruction, peak cylinder pressure, peak heat release rate, brake thermal efficiency, exergy efficiency, exhaust gas temperature and entropy generation rate. The thermodynamic analysis indicates that the combination of IT = 29 degrees BTDC and CR = 18 gives an improved performance of the biogas-run dual fuel diesel engine. (C) 2015 American Society of Civil Engineers.