Development of Three-Zone Transitional Model for Reciprocating Internal Combustion Engine Analysis Using Gasoline

A three-zone model based on the first law of thermodynamics has been developed for analysis of combustion in an Internal Combustion Engine. The three zones included an unburned zone, burned zone and transitory zone which is a mixture of burned and unburned gases. The model was used to analyse an SI engine operating with gasoline fuel. An arbitrary constant for each of fractional burnt zone (CC2) and fractional unburned zone (CC1) leakages was varied using 0.0005, 0.00025, 0.001, 0.002, 0.005, 0.1 and 0.5. The engine operating conditions were set at a speed of 2000 rpm, -35bTDC ignition time and burn duration at 600. The obtained indicated mean effective pressure (IMEP), thermal efficiency (η), cylinder pressure and emission characteristics from the developed model and those of two zone analysis were both compared with literature values. Most favourable results were observed at CC1 and CC2 values of 0.00025 and 0.005 respectively. We can conclude the 3zone model predicts better the IMEP, η, and peak cylinder pressure. However, no significant change was observed in values of emission characteristics of the 2zone and 3zone models. It is worthy of note that the number of zones affects engine performance evaluation and the higher the computational zone the better the engine prediction.