Preparation and Evaluation of PCMs by Macro Encapsulation for Solar Energy Storage

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%.