Subcooled flow boiling of ethylene-glycol/water mixture in an inclined channel with a hot spot: An experimental study

Subcooled flow boiling plays an important role in many industrial systems like Internal Combustion Engines (ICE). The main reason of its extensive application is its high potential of heat removal due to the fluid latent heat. The ethylene-glycol/water mixtures have been used as engine coolants for several decades. In this study, the effects of some parameters such as surface roughness, fluid velocity and surface inclination on the subcooled flow boiling of ethylene-glycol/water mixture with 50-50% volume fraction (WEG50) are investigated experimentally. An experimental test rig with the most resemblance condition to an ICE water jacket is set up and comprehensive data are collected. The setup consists of a 12 mm circular heater that is placed on the lower wall of a 20 x 30 min(2) channel and the WEG50 is used as the working fluid. Based on the experimental data, two new independent empirical correlations are presented to predict the subcooled flow boiling heat transfer inside the horizontal channel with good accuracy. The experimental results show that by increasing the test section surface roughness and fluid velocity the surface heat fluxes increase too. Inclination of the surface in either direction yields higher heat transfer coefficient in comparison to its horizontal position when the surface is smooth but lower for the rough surface. (C) 2016 Elsevier Ltd. All rights reserved.