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In the continuing search for highly efficient technical cooling devices, the nucleate flow boiling regime is becoming increasingly appreciated for providing the highest possible heat transfer rates. Regarding the case of liquid cooling systems of combustion engines, it is known that subcooled boiling occurs in thermally highly loaded regions. Therefore, reliable thermal management requires sufficient knowledge on how specific operation conditions and system parameters typically found in engine cooling jackets can affect the subcooled boiling heat transfer. In particular, the present work investigates experimentally the effects of varying volume fractions of the two main components of the coolant, of varying roughness and orientation of the hot wall surface with respect to the vector of gravitational acceleration, and of vibrations of the hot surface. The obtained comprehensive data set is highly valuable to elucidate and quantify the impact of the investigated effects. The data are also used to evaluate the performance of a wall heat flux model, which was specially developed for use in subcooled boiling flow in automotive applications. The model is proven to provide good overall accuracy for the considered experimental conditions.

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