Improvement of phase change materials loading on kaolin for temperature control of a co-axial cable surface

Renewable energy sources are best alternatives of fossil fuels. Latent heat thermal energy storage (LHTES), as a significant renewable energy source, is one of the promising methods to enhance the efforts against energy crisis since it could storage high density of energy, depending on the melting point of phase change material (PCM). Paraffin wax, free fatty acids, etc. as the organic PCM have lots of advantages including large range of availability, chemical stability, non-corrosivity, no or little super-cooling, etc. leakage is one of the main disadvantages of PCMs that limits the applications of them. To overcome the leakage issue, form-stable phase change materials (FSPCM) have attracted lots of attentions in the past few years. Kaolin, a kind of clay-based mineral, is a supporting material with distinguished peruse structure, cost effective, high specific surface area. Losses in electrical cables appears as heat in them that results in temperature increment of conductor therefore the current carrying capacity of a cable will be limited. So cable cooling is a crucial object that must be reached.In this study, a number of experimental samples using stearic acid (SA)/kaolin were prepared as a form of stable composite phase change materials (FSCPCMs) via melt impregnation method. The leakage of impregnated PCMs was tested using solution method. About 2 g of made-up composites were placed in 20 ml of n-hexane solution and were mixed about 4 minutes in 35°C. Then the treated composites were placed into the drying oven in 70°C for 2h. Fig.1. shows the results of the leakage test, as can be seen from fig.1 the maximum loading of SA in kaolin was about 50% indicating that the impregnation process was successfully done. The prepared composites could be mixed with the outer jacket (commonly PVC) to keep the cable surface temperature in comfort range.

Keywords:

PCM , loading , kaolin , stearic acid