Numerical Performance Studies of a Single Cylinder Spark Ignition Engine

This paper is a numerical study of the performances of a single cylinder, four-stroke(4S) Gasoline (SI) engine. A number of inputs such as compression ratio (CR), engine speed (RPM), bore, stroke, fuel–air equivalence ratio (ϕ), temperature, valve timings etc., were used for developing a MATLAB code for the purpose of engine simulation. The model employs Wiebe's heat release model, Blair's friction model and Annand's heat transfer model to predict the various properties with regard to the crank angle. By varying the input parameter such as CR, ϕ and RPM, various performance parameters like Brake Power (BP), Thermal efficiency (ηth), Brake specific fuel consumption (BSFC), Torque etc., were calculated. The performance parameters were measured based on a single cylinder SI engine with bore diameter 87.5 mm, Stroke length 110 mm, CR varying between 6 and 12, RPM at 1500 rpm and 2000 rpm [1 CYLINDER 4 STROKE MULTI-FUEL ENGINE TEST RIG Instruction Manual] and Load 0.8. The BP had a maximum value of 4.83 kW at CR 12 and 2000 RPM. Maximum value for BSFC was obtained as 594.688 g/kWh at CR 6 and 2000 RPM. Maximum torque was obtained as 23.2 N-m at CR 12 and 1500 RPM and maximum thermal efficiency was obtained as 17.54% at 1500 RPM and CR12. Variation of ϕ resulted a maximum BP as 4.032 kW at a ϕ value of 1.1764 and a speed of 2000 RPM. At a value of ϕ equals to 1.25 and at 2000 RPM, the maximum BSFC was 756.381 g/kWh, while maximum thermal efficiency was 14.01% at 1500 RPM at stoichiometric mixture.