COMPARATIVE ASSESSMENT OF A SPARK IGNITION ENGINE FUELED WITH PETROL AND RAW BIOGAS
In the current investigation, a single cylinder, 4-stroke, water cooled, manifold injection, variable compression ratio (VCR) SI engine of rated power of 4.5 kW @ 1800 rpm (Make: Apex Innovations) is operated both with petrol and raw biogas at a CR of 10:1 under 100% wide open (WOT) and 50% part throttle (PT) conditions. The engine was coupled with an eddy current dynamometer (SAJ Make, Model AG10) for loading. The baseline test is performed with standard petrol and subsequent experiments are carried out with biogas. The engine performance, combustion and emission characteristics are measured over a range of speed variations (1450-1700 rpm) through a computerized data acquisition and control system. Comparative analysis of the result showed 18 % of reduction in brake power, 66 % of increase in brake specific fuel consumption and 12 % of reduction in break thermal efficiency when the engine is fueled with raw biogas compared to that with the gasoline at WOT condition. However, the emission components such as CO and NOx are significantly reduced by 40 % and 81.5 %, respectively. While, the unburnt hydrocarbon (HC) and CO2 emission were increased by 6.8 % and 40%, respectively.