CORRELATION METHODS OF RAYLEIGH-BÉNARD CONVECTION IN A FLUID LAYER WITH PHASE CHANGE MATERIAL PARTICLES

Abstract

Two new methods for correlating experimental data of Rayleigh-Bénard convection in a fluid layer dispersed with phase-change-material particles have been proposed. Instead of the conventional arithmetic mean temperature method, two new methods for evaluating the intensity of convection in a horizontal fluid layer with strongly temperature-dependent specific heat were given. One method is by introducing a modified Stefan number in a Nu-Ra correlation or using the integrally averaged specific heat across the layer for calculating the Rayleigh number. The other method is by using the supercriticality (Ra/Rac) as an intensity parameter, in which the critical Rayleigh number Rac can be calculated by using the linear stability theory. Two models of non-dimensionalized apparent specific heat functions with respect to temperature were introduced. Results show that the two proposed methods are more rational comparing with the convectional 1/2-height rule method.