Study of cold start air–fuel mixture parameters for spark ignition engines fueled with gasoline–isobutanol blends

Biofuels are set to play an important role in the future strategy of automotive fuel suppliers, and therefore the study of using alcohols in spark ignition engines has become a necessity. A simple thermodynamic model was developed for calculating air–fuel mixture parameters for port injection engines fueled with gasoline–isobutanol blends, and theoretical results were compared to experimental values. For simulating the evaporation process, gasoline was considered a mixture of four components, with isobutanol added in different proportions. As all engine components are at ambient temperature during cold starts, mixture formation was considered an adiabatic process, with the fuel breaking up into droplets and evaporating, thus resulting in a temperature drop. A port injection engine fitted to a passenger car was used to validate the model for calculating air–fuel mixture parameters.