The local heat transfer coefficient determination during boiling a subcooled liquid on a superheated surface by the gradient heatmetry

Abstract

The article presents a comparison of the experimental local heat transfer coefficient and the heat transfer coefficient obtained by well-known empirical formulas. To calculate the heat transfer coefficient for stable pool film boiling according to the formulas given in the classical literature, it is necessary to know exactly the thermophysical parameters of the liquid and vapor at a given pressure and temperature. This approach satisfactorily describes the heat transfer coefficient during the boiling of homogeneous liquids. When calculating the heat transfer coefficient during the boiling of a suspension of particles in a liquid such an approach is impossible, because the exact values of thermophysical parameters for such a system are unknown. A new approach is proposed for determining the local heat transfer coefficient during boiling using gradient heatmetery. The method based on the use of heterogeneous gradient heat flux sensors allows the direct measurement of the heat flux per unit area. And with a known temperature difference, using thermometry, according to Newton's law of cooling, it is possible to determine the local heat transfer coefficient without reference to the thermophysical parameters of the liquid and vapor.