Heat Transfer With a MicroPCM Suspension in Laminar Tube Flow Using a Realistic Melting Model

Abstract

A microPCM fluid is a suspension of particles of microencapsulated phase-change-material (PCM) in a carrier heat transfer fluid. Such fluids have potential as pumped loop cooling media for applications in aerospace electronics cooling, terrestrial energy systems, and recently in electric vehicle cooling. The melting process of the phase change material does not occur at a single temperature but rather occurs over a temperature range. In the past, numerical solutions to microPCM fluids have assumed a linear release of latent heat over the phase change region. In this paper four analytic curve fits to differential scanning calorimeter measurements are made to better model the actual melting/solidification behavior. The numerical scheme models hydrodynamically fully developed laminar flow in a circular tube using the enthalpy method. The microPCM fluid contains 23% by weight microencapsulated octacosane particles in a 50/50% by volume ethylene glycol/water carrier fluid. A prescribed uniform heat flux at the tube wall is used. The solutions for these four cases include mixed mean exit temperature, axial tube wall temperature and local heat transfer coefficient.