Immersion corrosion tests on metal-salt hydrate pairs used for latent heatstorage in the 32 to 36 degrees C temperature range

During the last decades, energy storage has become more and more important. It is required in order to utilize alternative energy sources, which often are available at times when energy is not needed. The main applications of PCMs (Phase Change Materials) in thermal energy storage are when space res trictions limit larger thermal storage units. But widespread use of latent heat stores has not been realized till today due to two main problems: the low heat flux, and the insufficient long term stability of the storage mate rials and containers. In the present work, we studied this second problem s electing different common metals (aluminum, brass, copper, steel, and stain less steel) and testing their corrosion resistance in contact with salt hyd rates that are used as PCMs (zinc nitrate hexahydrate, sodium hydrogen phos phate dodecahydrate, calcium chloride hexahydrate). The method used was the immersion corrosion test. The tests here presented and evaluated were shor t term. As a consequence of the results from the experiments several pairs can be ruled out. The combinations of zinc nitrate hexahydrate with stainle ss steel, sodium hydrogen phosphate dodecahydrate with brass, copper and st ainless steel, and calcium chloride hexahydrate with brass and copper share d no significant corrosion in the short term and should be studied further.