Analyse und Vorausberechnung der Brennverläufe von Gasmotoren bei Einsatz verschiedener Gasarten

Today gas engines are mainly used as stationary power units in block heating power stations. Compared to diesel fuels natural gas causes less than 25% CO2-emissions for the same amount of energy. Thus natural gas makes an important contribution to the reduction of CO2 and other pollutants. The regionally different composition of natural gas, as well as the addition of propane/butane in order to cover the peak load by the gas suppliers, leads to a large scale of knock resistance. Even small methane number variations have a great effect on the operation of the engine. Increasing environmental awareness requires not only pure natural gas being used as fuel but also burnable gases from rubbish tips, such as bio and waste gas, as well as residual gases from chemical processes. As a consequence these gases have wide variations in its composition and, therefore, in the properties of the fuel. For that reason the optimum design of an engine operating with various mixtures of combustion gases requires the simulation of the operating behaviour and the analysis of the combustion process. The necessary basic research in this field had not previously been accomplished. The objective was to close these gaps and with the help of process calculation to enable a prediction how different gas mixtures perform being used in combustion engines. The necessary basic research to determine this relationships has been carried out for lean burn engines with pilot injection and for externally ignited lean burning engines with and without a scavenged prechamber. In addition an established procedure for diesel engines to predict the nitrous oxides has been adapted for the use with lean burning gas engines. Beside the test data obtained, the prediction equations produced have been used to validate these models.