A diagnostic quasi-dimensional model of heat transfer applied to a motored compression-ignition engine

The main objective of this research was to develop a heat transfer model that was less empirically based than the existing zero-dimensional models in order to provide a more accurate foundation for evaluating the combustion and resulting thermal stresses generated by alternative fuels in diesel engines. Particular attention was paid to the development of a spatial and temporal model of convective heat transfer that was based on gas flow characteristics. The complete model was formulated in such a way that it could be applied with the aid of a micro-computer. This paper deals with the verification of the model under motored engine conditions. Tests were carried out on a naturally aspirated ADE 236 engine involving the measurement of cylinder pressure and heat flux at a single point in the engine for different speeds. Motored engine data were used to verify the convective heat transfer rates. Close correlation between predicted and measured heat flux was achieved after accounting for the effects of chamber geometry at the probe site.