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In recent years, the need to optimize the performance and reduce exhaust emissions of internal combustion engines has caused the design of the auxiliary (like lubrication and cooling pumps) to assume a particular importance. This is especially due to the necessity to obtain higher efficiency with less expense in terms of work assigned to these organs. With respect to the lubrication circuit, this means the use of solutions that allow the optimization of the fluid dynamics of both the ducts and the pump. This work is based on a simulated analysis carried out on the lubrication circuit of a light duty internal combustion engine, developed by Fiat and equipped with a hydraulic VVT system.

With the increase of specific power, in development of modern engines, also the demand on the cooling system has significantly increased. CFD analysis reveals the occurrence of localized boiling, since often the measured temperature distribution cannot be explained by convective heat transfer alone [1]. The requirement for highest heat transfer rates has led to the very promising concept of a controlled transition from pure convection to subcooled boiling in the critical thermal conditions [2]. However, computational fluid dynamics is still unable to represent boiling flow, while any boiling based strategy requires a right prediction of heat transfer rates on the coolant surface inside IC engines. Chen's heat transfer model for boiling region [1, 2, 4, 6] is widely used today, to predict and compare the predicted heat transfer coefficients in circular and rectangular ducts with experimental results.