Heat transfer correlations for open-cellular porous materials

摘要

A general correlation for volumetric heat transfer coefficient between stream of air and open-cellular porous materials was derived utilizing experimental data obtained by several researchers. The derived correlation is written in form of h_v=(A/D_s~(2-n))u~n. Here, h_v denotes the volumetric heat transfer coefficient, A is the constant, n is the velocity exponent, u is the mean fluid velocity and D_s is the equivalent strut diameter of Dul'nev's unit cell for open-cell foam. The parameters, A and n, were determined by a least-square fit of the expression to the above-mentioned experimental data to give A=13.0 and n = 0.791. Moreover, from the h_v-u correlation thus determined, the following Nusselt vs. Reynolds number heat transfer correlation was proposed: Nu_s=0.124(Re_sPr)~(0.791), where Nu_s represents the Nusselt number defined by h_vD_s~2/k_f, Re_s denotes the Reynolds number defined by uD_s/v_f, Pr is the Prandtl number, k_f is the thermal conductivity of fluid and v_f is the kinetic viscosity of fluid. It is found that this correlation approximates 78.1% of the available experimental data with an error of less than ± 40%.