Development of a heat transfer coefficient based design method of a thermal energy storage device for transport air-conditioning applications

Abstract

We studied the heat transfer characteristics of a phase change material (PCM) based thermal energy storage (TES) device for transport air conditioning applications. The charging and discharging times and the transient heat flux of the TES device were measured. These data allow quantification of the transient and overall heat transfer coefficients, thus a quantitative comparison between the overall heat transfer coefficients of the charging and the discharging processes. An attempt was made to process the overall heat transfer coefficient data to give the Nusselt number, the Reynolds number, and the Prandtl numbers for both the discharging and charging processes. An empirical relationship between these non-dimensionless numbers was then obtained, which was validated by further experiments. It was shown that the empirical expressions agree with the further experimental data within 2.33% and 1.65% respectively for the charge and discharge processes. To our best knowledge, this study represents the first effort to measure the transient behavior of a PCM based TES device, leading to a set of experimentally validated empirical expressions for the overall heat transfer coefficients.