Experimental study of combustion in a spark ignition engine operating with producer gas from various biomass feedstocks

•Lower cylinder pressures and heat release rates for producer gas compared to propane.•Power loss, due to the lower calorific value of producer gas, did not exceed 10% for the studied mixtures.•Slower flame propagation in the combustion chamber, for the producer gas than propane.•Moderate effect of producer gas on combustion stability.•All phenomena were more intense at the case of the producer gas by grape kernels.

Spark-ignition engines running on gaseous fuels are commonly used for combined heat and power (CHP) production. In the present work, an experimental investigation has been conducted in order to study combustion in a spark-ignition engine fueled with producer gas. The engine is a single cylinder one, coupled to a fluidized bed gasifier in a mobile combined heat and power (CHP) production unit. Three biomass feedstocks were evaluated, which are olive, peach and grape kernels. Mixtures of each producer gas separately with propane at various blending ratios were fed to the engine, operating at various engine speeds. Cylinder pressure measurements were performed, followed by heat release rate analysis. Loss in power output compared to neat propane operation was experienced, owing to the lower calorific value of the producer gas, independently of the feedstock. Additionally, lower cylinder pressures and heat release rates were observed, coupled to prolonged combustion duration. Finally, combustion stability was moderately affected by the introduction of producer gas.