Gas exchange modeling of a single-cylinder engine

Abstract

Fossil fuels are dominating the transport sector but due to concerns regarding the climate change, oil resources availability and conflicts in the world, the interest of alternative fuels has increased. Therefore, the purpose of this work is to model a single-cylinder GT-Power gas exchange model that is running on the alternative fuel, dimethyl ether (DME). The model aims to simulate in-data necessary for further development of the combustion process that will be carried out through CFD analyses. The model will be verified through measured test data of previously performed DME engine tests. This thesis work resulted in a predictive combustion model, DIPulse, with exhaust gas recirculation (EGR) that is calibrated for two engine load points, B50 and C100. It is able to handle a wide range of EGR amounts and injected fuel masses. CO2 predictions for inlet- and exhaust gases have 9.5% and 4.8% accuracy respectively compared with measured lab data and the maximum cylinder pressure has an accuracy of 1.2%. However, the model can neither handle transient behaviors nor load points other than B50 and C100. It was difficult to achieve accurate CO2 concentration levels that agrees with the measured data. However, consistent results from the simulations are expected to be difficult to achieve due to significant variations in measured CO2 concentrations during engine tests.