A Model for a Fast Prediction of the In-Cylinder Residual Gas Mass

The presented results are part of a research project to create a universal residual gas fraction model. It is supported by the „Forschungsvereinigung Verbrennungs-kraftmaschinen e.V. (FVV)”.

In the research project an universal formula has been developed which allows the determination of the residual gas fraction in allkind of IC engines. The formula is valid for naturally aspirated engine, turbo and super charged, variable valve timing and fully variable valve trains, as well. The formula (constant approach) developed during the project is based on variables like time averaged intake and exhaust pressure, exhaust temperature and geometric engine data which were measured on the test bench. As a result, online and real time calculation is possible already while the engine is running. This implies that the formula can be used within the engine control unit for control purposes. The comparison of the results from the thermodynamic gas exchange analysis and the 1-dimensional simulation (GT-Power) shows a good correlation with the experimental results. The outcome of the newly developed calculation method (constant statement) obtain simple models of Heywood and Müller-Bertling[1, 2, 6, 9]. The improved values can be used for fast in advance calculations of the internal residual gas mass.