Numerical investigation of heat transfers in the water jacket of heavy duty diesel engine by considering boiling phenomenon

Abstract

The flow of the coolant fluid and its heat transfer directly affect the cooling performance, heat load of the hot parts and also the thermal efficiency of the diesel engine. The proper estimation of heat transfer and temperature distribution in a diesel engine is essential for investigating the thermal stresses and calculating its performance, which requires a precise simulation of the cooling water jacket. An efficient approach to study the cooling system is to simulate using Computational Fluid Dynamics (CFD) as a three-dimensional model by simultaneously solving the structure and fluid, which leads to accurate prediction of wall temperature and heat flux. In the present paper, the distribution of heat transfer coefficients (HTC) in the cooling jacket of a 16-cylinder heavy-duty diesel engine has been calculated using ANSYS/Fluent based on 3D-CFD method. Also, equations of subcooled boiling phenomenon have been solved based on methods of Chen and BDL, and the effects of fluid pressure, velocity, and temperature (At the time of the phenomenon of boiling) on the heat transfer of cooling jacket wall have been studied. The results show that the sensitive thermal region that is at risk is the region between the exhaust valve and around the glow-plug. This region if not properly cooled, will result in gas leakage from the combustion chamber, which will result in a decrease in engine power and torque. Keywords: Heavy duty diesel engine, Cooling jacket, Heat transfer, Subcooled nucleate boiling, Numerical Simulation