Methods to Evaluate In-Cylinder Heat Transfer and Thermal Load in the Small Internal Combustion Engines

The manufacturers continually look for improved methods to design engines. Increased durability, enhanced engine performance, decreased emissions and low cost are all issues to consider during the early design stages. The purpose of this paper is to investigate the thermal flows and heat transfer phenomena occurring in the small engines and to suggest valid methods for their prediction to be used inside computer design software. A new approach to theoretically calculate the heat transfer based on the thermal vibrational convection theory is first proposed. The basic idea of this approach is that the heat transfer process can be correlated mainly with the thermal explosion and with the detonation wave produced by combustion. Later on, a simplified model based on energy balance method is investigated and its use in the engine computational software is proposed showing how it represents the best solution to develop a software procedure to simulate heat transfer.