Thermodynamic Simulation of Spark Ignition Internal Combustion Engine Operation with Blends of Gasoline and CNG with Experimental Verification

Regarding environmental pollution of internal combustion engines and depletion of fossil fuels resources, compressed natural gas has been considered as an alternative to gasoline in vehicle applications. As supplementary fuel for spark-ignition engines, CNG has some advantages over gasoline, such as higher octane number and reduction of CO2, CO and UHC emissions. In this paper, a quasi-dimensional thermodynamic predictive model used to simulate the working cycle of a 4-stroke spark ignition engine fueled with gasoline,CNG, and their mixture for variable mass CNG fraction. The model predicts the performance parameters such as power, ISFC and environmental emissions including CO2, CO, UHC and NO. The results obtained from the present study have been compared with the experimental data. The experiments have been done on a bi-fuel CNG-gasoline engine for gasoline, CNG and the dual fuel operations. The results for pressure traces and performance parameters of the engine showed a good agreement with corresponding experimental data.