Thermophysical properties of working fluid and heat transfer in a hydrogen combustion engine

A larger burning velocity and a shorter quenching distance for hydrogen as compared with hydrocarbons bring a higher degree of constant volume and a larger cooling loss from burning gas to the combustion chamber wall in internal combustion engines. Because of the large cooling loss, the reduction of the cooling loss are crucial for improving the thermal efficiency in hydrogen combustion engines. Empirical correlation for total heat transfer from burning gas to the combustion chamber walls are often used to calculate the cooling loss. However, previous research by the authors has shown that the widely used heat transfer correlation reported by Woschni cannot be properly applied to the hydrogen combustion. For this background, this research analyzes the relationship between characteristics of thermophysical properties of working fluid and heat transfer to the wall in a hydrogen-fueled spark-ignition engine.