Performance investigation of a modified small engine fueled with producer gas

Producer gas from biomass gasification can be used as a replacement fuel in spark-ignition engines. In this study, a small, single-cylinder, naturally aspirated diesel engine was modified into a spark-ignition engine. A conventional swirl chamber was replaced by a bath tube combustion chamber. Optimum spark ignition time was set for each engine speed to give maximum brake torque. It was fueled with 100% producer gas and coupled to a 5.0-kW dynamometer. A downdraft gasifier was used to generate producer gas from charcoal. Engine performance in terms of engine torque, brake power, brake thermal efficiency and brake specific fuel consumption were evaluated at variable compression ratios between 9.7:1-17:1. Engine speed and load were varied between 1100-1900 rpm and 20-100% respectively. At a certain combination of compression ratio, engine speed and load, deceleration and knocking were detected. Maximum engine torque and brake power were 18.6 Nm and 3.3 kW respectively, at a compression ratio of 14:1, full load and 1700 rpm. The best specific fuel consumption of 0.94 kg/kWh and maximum brake thermal efficiency of about 19% were obtained.