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

[Display omitted] •An innovative technique to encapsulate high temperature PCM is presented.•No need of a sacrificial layer to accommodate the expansion of the PCM on melting.•Non-vacuum metal deposition process for large-scale fabrication of capsules.•Capsules survived thermal cycles, equivalent to seven years of power plant service.•No degradation in thermophysical properties of the capsules and PCM on cycling. 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.