Experimental investigation of methane-enriched biogas in a single cylinder diesel engine by the dual fuel mode

In this experimental work characteristic such as performance, combustion and emission of a single cylinder, four-stroke constant speed, direct injection, water-cooled diesel engine is investigated. The engine is operated by dual fuel mode using methane-enriched biogas (88.10%-CH4 + 11.89%-CO2) obtained from the food waste. Biogas (BG) is inducted into the engine at intake manifold with various mixtures like BG20, BG30 and BG40 mixed with air (i.e. BG40-40% of CH4 by mass respectively) at actual injection timing of 27.5 degrees before top dead centre (bTDC) for different loads. The performance, combustion and emission characteristics of the engine operated by dual fuel mode were experimentally investigated, and compared with respect to diesel. By observing the experimental results, BG40 was optimized on the basis of lesser emissions and improved performance. BG40 showed lesser brake thermal efficiency and higher brake specific energy consumption than BG20 and BG30 for all loads. On the other hand, BG40 showed lower BTE by 15.5% and 15.62% compared to diesel at 3/4(th) and full load. Whereas the cylinder peak pressure for BG40 is higher than diesel by 5.36% and the net heat release rate is 14.9% higher than the diesel at full load. BG40 emitted higher carbon monoxide (CO) emissions than diesel by 5% at full load. The nitrogen oxide (NOx) emission for BG40 was lesser by 26.60% than diesel at full load, whereas the soot emission was 22.71% lower than diesel at full load respectively.