Maximisation of heat transfer in a coil in tank PCM cold storage system

Thermal energy storage systems for both heat and cold are necessary for many industrial processes. High energy density and high power capacity are desirable properties of the storage. The use of latent heat increases the energy density of the storage tank with high temperature control close to the melting point. Tube in PCM tank is a very promising system that provides high packing factor. This work presents an experimental study of a PCM tank for cold storage applications. Two different configurations and different flow rates of the heat transfer fluid were studied. The effectiveness of the PCM storage system was defined as that of a heat exchanger. The results showed that the heat exchange effectiveness of the system did not vary with time, decreased with increasing flow rate and increased with increasing heat transfer area. The effectiveness was experimentally determined to only be a function of the ratio m˙/A. This equation was found to be adequately be used to design a PCM storage system, and a case study is presented. It was shown that the tube in tank design together with a low temperature PCM is suitable as a thermal storage facility for cold storage.

► The use of PCM for cold storage (at temperatures between 0 °C and –40 °C) is investigated, since little work was developed in this field.
► Most of the studies related to cold storage have focused on PCM in spheres. A tube in tank design warrants investigation.
► An empirical relationship is determined to identify the effectiveness and determine design parameters readily applicable to design.