Numerical investigation on melting behaviour of phase change materials/metal foam composites under hypergravity conditions

Abstract

The integration of electronic devices in aerospace vehicles leads to a significant increase in the heat dissipation, which makes thermal management a severe challenge. Due to the high thermal energy storage capacity and the excellent thermal diffusivity, phase change materials (PCM)/metal foam composite is a potential thermal management material. In order to deepen the understanding of melting behaviour of PCM/metal foam under hypergravity, the numerical model considering natural convection, flow resistance of metal foam, and non-equilibrium heat transfer is proposed, and the effects of inclination angle, hypergravity value, metal foam porosity, and pore density on the melting are analyzed. It shows that the inclination angle has a great influence on the morphology of the melting interface, while has limited influence on the variation of PCM liquid fraction. As the inclination angle changes from 0° to 180°, the heated wall temperature first decreases, and then increases after reaching the lowest value at 45°, which is the optimal inclination angle. With the rise of hypergravity value, natural convection is enhanced, the heated wall temperature is reduced, while the hypergravity value has limited effect on the PCM liquid fraction. Furthermore, with the increase of metal foam porosity, natural convection is enhanced, while the heated wall temperature and the melting time become larger. When the porosity is larger than 0.95, the effect of metal foam on natural convection suppression is greater than that of heat conductivity enhancement, leading to that the performance of PCM/metal foam is worse than that of the pure PCM. Besides, with the decrease of pore density, natural convection is enhanced, the heated wall temperature becomes lower. Therefore, metal foam with lower pore density is preferred. This paper provides guidance to the optimal design of PCM-based heat sink for aerospace applications.