Effect of fuel and engine operational characteristics on the heat loss from combustion chamber surfaces of SI engines

Understanding of engine heat transfer is important because of its influence on engine efficiency, exhaust emissions and component thermal stresses. In this paper, the effect of various parameters such as compression ratio, equivalence ratio, spark timing, engine speed, inlet mixture temperature and swirl ratio as well as fuel type on the heat transfer through the chamber walls of a spark ignition (SI) engine is studied. For this purpose, a proper tool is developed which uses a KIVA multidimensional combustion modeling program and a finite-element heat conduction (FEHC) code iteratively. Also, an improved temperature wall function is used for the KIVA program. It was found that this iterative scheme and the new wall function can improve the predictions considerably. A parametric study shows that this methodology is efficient in predicting the engine heat transfer and the effects of changes in the fuel type and engine operational parameters on the engine thermal behavior.