Combustion Chamber Pressure and Temperature Analysis Based on Heat Release Rate Parameters of a Spark Ignition Engine

Internal combustion engines have been developed and widely used since the last century, and they continue to be extensively employed today. Engine development has progressed significantly, and due to the environmental impacts caused by their use, new technologies are being developed to reduce pollutant formation after the combustion process and to increase thermal efficiency. Computational modeling is a tool that has supported this development and can be categorized into three types: zero-dimensional, quasi-dimensional, and three-dimensional models. The 0D and 1D models offer a good balance between computational processing time and result uncertainty when compared to three-dimensional models. The Wiebe function is a simple analytical approach capable of describing the fuel burn rate in combustion engines. Previous studies have shown that applying this function yields results that accurately describe the apparent heat release rate in PFI engines.The present study aims to determine the pressure curve using the Wiebe function and the heat release rate theory developed by Heywood. The tests were conducted on a four-cylinder spark-ignition engine fueled with regular type C gasoline, operating under two different torque conditions. Based on the proposed model, the temperature gradient during the combustion process was obtained. Tools capable of measuring in-cylinder pressure and temperature are robust but have high operational costs; therefore, predictive models can significantly reduce expenses associated with such measurements. The results were compared with data collected from bench dynamometer tests for validation.