AVAILABILITY ANALYSIS OF A BI-FUEL SI ENGINE MODEL FOR IMPROVEMENT ITS PERFORMANCE

This paper characterizes the exergy (availability) analysis in bi-fuel (CNG and gasoline) spark ignition engines. The engine is modeled based on a thermodynamic quasi-dimensional (QD) two-zone model. It solves the differential equations related to compression, combustion and expansion. By an approximation method, intake and exhaust processes are modeled. Using a turbulent combustion model, the engine model has capable to simulate burn rate, and compared to computational fluid dynamic (CFD) models is faster. To meet this objective, this model is developed based upon the second law, and exergy analysis terms. These terms are including thermo-mechanical availability, chemical availability, heat transfer availability, work availability, and the irreversible processes that are the source of availability destroyed. Finally, in this paper the effect of equivalence ratio, ignition time and engine of speed upon the terms of availability, the first law of thermodynamics (FLT) and the second law of thermodynamics (SLT) efficiency are presented and are discussed.