Separation of power and capacity in latent heat energy storage

The state-of-the-art latent heat energy storage system is equipped with aluminum fins at the heat exchanger pipes in order to compensate the low thermal conductivity of the phase change material (PCM). The necessary amount of fins is directly coupled to the capacity of the storage system, what makes larger systems expensive. The PCMflux concept is developed in order to realize both a controllable and a possibly more cost effective latent heat storage system. These aims are addressed by separating the storage material from the heat exchanger. As a result, the PCM can be moved over the heat exchanger. The PCM thereby is macroencapsulated into containers. These pass the heat exchanger while the PCM inside changes phase. In order to improve thermal contact between containers and heat exchanger, Hitec® as an intermediate fluid is used to avoid poor dry contact. In this article, an experimental setup is described to examine the heat transfer through thin layers of molten Hitec®. The results of the experiments show an increased heat transfer by a factor of 9.9. This improves feasibility of the PCMflux concept significantly. © 2015 The Authors. Published by Elsevier Ltd. Peer review by the scientific conference committee of SolarPACES 2014 under responsibility of PSE AG.