An Experimental Study of a LTES with Compact Heat Exchanger Model

Abstract

The critical challenge in designing a thermal energy storage is enhancement of the heat exchange between the fluid and the stationary storage material. The aim of this study was to design a thermal energy storage for storing energy from hot air in a paraffin wax-based phase change material (PCM). A commercially available automobile air-cooled radiator has been used as heat exchanger between air to PCM due to high heat transfer coefficient. The air was passed through the inner micro-channels of the heat exchanger, and the heat exchanger was immersed in paraffin wax. The charging and discharging of the storage unit were studied. During the charging process, a temperature difference of 40–\(50\,^{\circ }\mathrm{C}\) was observed between inlet and outlet air, which suggest high heat transfer from air to PCM. During the discharging process, a maximum temperature difference of \(13.5\,^{\circ }\mathrm{C}\) between outlet and inlet air was observed. The outlet air was maintained at \(48\,^{\circ }\mathrm{C}\) for 22 min. The average temperature difference between solid–liquid interface of PCM and air inlet was at \(10.6\,^{\circ }\mathrm{C}\) during the discharge process. However, a uniform melting of PCM could not be achieved throughout the whole storage unit. Further modification of the compact heat exchanger with extended surface may lead to better performance of the thermal energy storage model.