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Residual gas plays a crucial role in the combustion process of SI engines. It acts as a diluent and has a huge impact on pollutant emissions (NOx and CO emissions), engine efficiency and tendency to knock. Therefore, characterizing the residual gas fraction is an essential task for engine modelling and calibration purposes. Thus, an in-cylinder sampling technique has been developed on a spark ignition VVT engine to measure residual gas fraction. Two gas sampling valves were flush mounted to the combustion chamber walls; they are located between the 2 intake valves and between intake and exhaust valves respectively. In-cylinder gas was sampled during the compression stroke and stored in a sampling bag using a vacuum pump. The process was repeated during a large number of engine cycles in order to get a sufficient volume of gas which was then characterized with a standard gas analyzer.

In order to simulate the working process, an accurate description of heat transfer occurring between in-cylinder gases and combustion chamber walls is required, especially regarding thermal efficiency, combustion and emissions, or cooling strategies. Combustion chamber wall heat transfer models are dominated by zero-dimensional semi-empirical models due to their good compromise between accuracy, complexity and computational efficiency. Classic models such as those from Woschni, Annand or Hohenberg are still widely used, despite having been developed on rather ancient engines. While numerous authors have worked on this topic in the past decades, little information can be found concerning the systematic calibration process of heat transfer models. In this paper, a systematic calibration method based on experimental data processing is tested on the complete operating map of a turbocharged GDI engine.

Diesel engines are being more commonly used for light automotive applications, due to their higher efficiency. However, pollutant emissions can be higher than their gasoline counterparts, being difficult to reduce and control because reducing one pollutant increases another. One way to reduce emissions is by using multiple injection strategies. However, understanding multiple injections is no easy task, so far done by trial and error and experience. Therefore, a numerical 1D model is to be adapted to simulate multiple injection situations in a diesel engine. In a previous paper by the authors, an existing model was adapted with a thermal dilatation model to consider both radial and axial dilatations in the diesel spray. The base model used is that of Ma et al (based on the Eulerian model of Musculus and Kattke for inert diesel jets).