Comparative Heat Transfer Data for Solid-Liquid Phase Change of D-Mannitol and Adipic Acid

Abstract

The goal of this work was to measure the heat transfer rates from thermofluid, Therminol 66, to two phase change materials, D-mannitol and adipic acid. It concerns the determination of heat transfer coefficients for the design of a concentrated solar energy plant requiring PCM thermal energy storage and is part of a wider set of experiments, where several PCMs were tested. An experimental installation was used with a cylindrical vessel with three tubes disposed almost horizontally (5˚ inclination), containing the phase change material, around which the thermal fluid flowed almost perpendicular to the tubes. The experimental installation allowed to recreate heating and cooling cycles. In order to evaluate the influence of the flow on the rate at which the heating and cooling processes took place, tests were performed at different thermofluid mass flow rates, concluding that there is no great influence, since the thermal resistance inside the tubes is much higher than on the outside. D-mannitol and adipic acid, present different phase change temperatures, 164˚C for D-mannitol and 152˚C for adipic acid. The average heat transfer coefficient, during the phase change process, was of 340 W/(m 2 K) for Dmannitol and 1320 W/(m 2 K) for adipic acid.