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In this work, heat loss was investigated in two different HCCI single cylinder engines. Thermocouples were adapted to the surfaces of the cylinder heads and the temperature oscillations were detected in a wide range of the engine operation maps. The resultant heat transfer profiles were compared to the heat losses predicted by existing models. As major discrepancies were stated, a new phenomenological model was developed that is well-manageable and describes the heat loss in HCCI mode more precisely than existing models. To analyze the insulating effect of deposits, the heat transfer equation was solved analytically by an approach that allows consideration of multiple layers with different material properties and thickness. This approach was used for the first time in conjunction with engines to calculate the heat flux at the surface of deposits and the deposit thickness.

In this work, heat loss was investigated in two different HCCI single cylinder engines. Thermocouples were adapted to the surfaces of the cylinder heads and the temperature oscillations were detected in a wide range of the engine operation conditions. The local heat transfer is analyzed with port fuel and direct injection, for different engine parameters and operating points. It is shown that the spatially averaged measured heat loss in HCCI operation represents the global heat loss well. The spatial variations are small in the operation map presuming stable operating points with low cyclic variations and good engine performance. Furthermore, the heat loss measured in HCCI operation is compared to the heat loss detected in homogeneous and stratified DI-SI operation in the same engine. It is shown that the local heat losses in stratified DI-SI operation show large variations, depending on the direction of the flame propagation.

The subject of this paper is the reduction of the particle number emissions of a gasoline DI engine at high engine load (1.4 MPa IMEP). To reduce the particle number emissions, several parameters are investigated: the large scale charge motion (baseline configuration, tumble and swirl) can be varied at the single cylinder engine by using inlays in the intake port. The amount of residual gas can be influenced by the exhaust backpressure. By using a throttle valve, the exhaust backpressure can be set equal to the intake pressure and hence simulate a turbocharger's turbine in the exhaust system or the throttle valve can be wide open and thus simulate an engine using a supercharger. Additionally, higher fuel injection pressure can help to enhance mixture formation and thus decrease particulate formation. Therefore, a solenoid injector with a maximum pressure of 30 MPa is used in this work.