Abstract

Background: Phase Change Materials (PCMs) are used in a latent heat storage system for storing thermal energy. The thermal conductivity of PCMs is enhanced by macro encapsulation for large-scale use.

Objective: This technique not only provides a self-supporting structure of PCM but also separates the PCM from thermal fluids and enhances the heat transfer rate.

Methods: The current work involves the study of encapsulation of low-cost inorganic PCMs, such as sodium nitrate (NaNO3), in a temperature range of 300 - 500°C. Silicate coating is also applied to PCM capsules. A solar water heater is then designed using the macro encapsulated PCM.

Results and conclusion: The water heater consists of cylindrical copper pipes filled with phase change material. The efficiency of the solar water heater is found to be 22.5%.

Keywords: Phase change materials, thermal energy storage, macro encapsulation, thermal conductivity, solar energy, thermal fluids.

Graphical Abstract