DURABILITY OF A SMALL AGRICULTURAL ENGINE ON BIOGAS/DIESEL DUAL FUEL OPERATION

Biogas from anaerobic digestion of organic waste is a potential alternative to the partialsubstitution of petroleum derived fuels because it is from renewable resources that are widelyavailable. The effect of long term durability tests using biogas/diesel dual fuel operation on wearcharacteristics is evaluated and presented in this paper. Steady state tests were performed on asmall, single cylinder, naturally aspirated, 4-stroke, direct injection diesel engine at a speed of1500 rpm, coupled to a generator set to generate electricity for over 3500 hours. Lubricating oilsamples were collected during the test run and were subjected to the analysis of various wear metaltraces present and the changes in their properties. After completion of the endurance test, theengine was dismantled for physical inspection and wear assessment of vital parts. Formation ofcarbon deposits on in-cylinder surfaces was not found to be problematic. Injector tip coking didnot occur. Surface wear and accumulations of metal debris in crankcase lubricating oil sampleswere analyzed and found to increase with time, but not at an unusual rate. Properties of usedlubricating oils did not alter significantly from their original values. Wear was not significantlydifferent in the test engine fueled with the biogas/diesel combination. An overall evaluation of theresults indicated that the biogas/diesel duel fuel operation could be substituted for diesel fuel inelectricity generation and worked satisfactorily under long term engine operation without anymajor troubles.