Solar energy storage by a two grade phase change material


  • Gábor Bajnóczy
  • Edit Gagyi Pálffy
  • László Szolnoki
  • Ernő Prépostffy


A two grade phase change material (PCM) based on CaCl_2-water system has been investigated in a PCM--water heat exchanger. The crystallization of different hydrates of CaCl_2 extended the temperature range of heat storage and the storage stability was achieved by the application of wood chips as thickening agent. A short section of the heat exchanger tube (a few cm) can be characterized by a maximum curve of heat transfer coefficient in function of cooling time. Longer sections (a few meter) showed nearly constant heat transfer coefficient in the range of 115 +/- 25 W/m2K. The heat storage system is to be applied to store solar energy and the stored heat is used to preheat the water input of domestic hot water supply system.


heat storage, phase change material, solar energy, heat transfer coefficient

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How to Cite

Bajnóczy, G., Gagyi Pálffy, E., Szolnoki, L., Prépostffy, E. “Solar energy storage by a two grade phase change material”, Periodica Polytechnica Chemical Engineering, 51(2), pp. 3–7, 2007.