Experimental and numerical comparison of bio-based and conventional phase change materials for thermal storage applications

Abstract

In the paper, the performance of two phase change materials (PCMs) is evaluated numerically and experimentally. Technical requirements, size limitations and time response of the PCM present crucial boundary conditions when choosing the right material and storage type in the residential sector. The latent heat thermal energy storage system analysed in this paper is a modified shell-and-tube type of heat exchanger using paraffin wax RT-28-HC and a bio-based substance PureTemp28 as phase change materials with heat storage capacity of 255 and 190 kJ/kg, respectively. Their phase change transition temperatures are between 27 and 29 C which makes them suitable for domestic applications together with underfloor heating and heat pump units. In order to properly validate the simulation results, a corresponding machine with the similar initial and boundary conditions has been set up. Additionally, to account for all possible impacts on the performance of the PCM, thermal storage unit was equipped with 24 radially distributed temperature sensors, a pump with variable rotational speed and a water supply machine that operates in temperature ranges from -50 to 150 C. The results from the experiment exhibit very good correlation with the numerical simulations concerning the charging and discharging times.