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A realistic simulation of engine thermal transient behavior requires a coupling between a combustion model and a thermal model of the engine cooling system. This paper describes a procedure used to realize such a simulation. We will develop reasons that lead us towards the choice of Hohenberg's correlation as an engine heat transfer model. A thermal transient simulation of air blown into the car cabin has been computed on a NEDC driving cycle. An experimental study in a wind tunnel has been carried out to validate the heater core heating power and air temperature simulations.

An extension of a thermodynamic methodology of TDC determination in IC engines is presented. The effect of an error on the TDC position coupled with an error on the compression ratio is analyzed in the temperature-entropy diagram. When the TDC position and the compression ratio are well calibrated, compression and expansion strokes under motoring conditions are symmetrical with respect to the peak temperature in the (T,S) diagram. Moreover, in case of an error on the TDC position, a loop appears, which has no thermodynamic significance. In the same way, in case of a compression ratio error the (T,S) diagram leans. Hence, an easy methodology has been conceived to obtain the right position of TDC and eventually to correct the compression ratio. This methodology is applied on motoring measurements to assess its performance.

A thermodynamic methodology of TDC determination in IC engines based on a motoring pressure-time diagram is presented. This method consists in entropy calculation and temperature-entropy diagram analysis. When the TDC position is well calibrated, compression and expansion strokes under motoring conditions are symmetrical with respect to the peak temperature in the (T,S) diagram. Moreover, in case of error on the TDC position, a loop appears, which has no thermodynamic significance. Hence, an easy methodology has been conceived to obtain the actual position of TDC. This methodology is applied to motoring measurements in order to present its performance, which are compared to usual methods.