Abstract:
This study addresses the design and modification of a gasoline generator to use biogas as an alternative fuel. The biogas was produced from fresh cow dung using a 10m3 fixed dome bio-digester and the produced biogas scrubbed to improve its energy content per unit volume. A 1.0 kW Tigmax air-cooled gasoline generator was used for the investigation. The modification involved the fabrication and mounting of a simple external mixing chamber on the air-duct of the carburetor. A comparative analysis of the performance and combustion characteristics of the engine was evaluated separately with petrol and biogas using ten number 100 watts bulb as variable loads. Power output was optimal at 0 to 500 watts, while rapid power output deterioration was noticed above load condition of 500 watts. Overall rated power output reduction of 47% was observed in the study due mainly to high percentage of carbon dioxide. Exhaust gas temperature of the modified engine was comparable to the unmodified engine at load condition of 100-200 W, above 200 W the exhaust temperature lost the linearity. The exhaust emission revealed an improvement in emission at load range of 100-200 W, while 200 W the achieved superiority was lost due to an increased emission of CO and CO2. Improving the scrubbing capacity of the purification and the external mixing chamber is here-by recommended
