Macroencapsulation and characterization of phase change materials for latent heat thermal energy storage systems

An innovative technique to encapsulate PCMs that melt in the 120–350°C temperature range is presented. The developed technique does not require a sacrificial layer to accommodate the volumetric expansion of the PCMs on melting. The encapsulation consists of coating a non-reactive polymer over the PCM pellet followed by deposition of a metal layer by a novel non-vacuum metal deposition technique. The fabricated capsules have survived more than 2200 thermal cycles, which is equivalent to about seven years of service in a thermal energy storage system. Thermophysical properties of the PCMs were investigated by DSC/TGA, IR and weight change analysis. Thermal cycling test showed no significant degradation in these properties at any stage of testing.