Downsizing in Diesel Engines - An experimental Investigation of Base Engine Design concerning the Diesel Combustion System based on Single Cylinder Engine Experiments

What would be the optimal engine size according to our specifications? This might be the most difficult question to answer at the beginning of a new engine development. All the technical fields from thermodynamics to mechanics have to be distinguished on a very high level of prediction accuracy. Just relying on experiences gained from established engine concepts and an estimated guess how the development of single components will contribute to the complete engine behavior. However, within the following publication the question is tackled from an academic side, just focusing on the physical aspects. The aim of the research is to show the sensitivity of single base engine parameters and give a suggestion for a highly efficient research vehicle with an optimised fuel economy meeting the EURO 6 emission targets. The investigation is performed on single cylinder engines ranging from 400 to 500 ccm displacement. Besides the evaluation of the friction influence, a very thorough thermodynamical analysis is performed. That enables a detailed distinction between the influences of the combustion process, the wall heat losses and the gas exchange. The sensitivity concerning the EGR, swirl, boost pressure and injection parameters are identified. Finally the single cylinder results are supported by numerical calculations and applied on a full 3 cylinder research engine in order to investigate the influence of the turbocharger.