Charging performance of latent thermal energy storage system with microencapsulated phase-change material for domestic hot water

A latent thermal energy storage system designed for domestic hot water is constructed using microencapsulated phase change material (MEPCM) as the energy storage medium. The temperature response and energy storage are experimentally investigated for different MEPCM particle fractions, PCM core fractions and carbon fiber fractions in the energy storage units (ESUs). A model for nominal energy storage is proposed. In the charging process, the ESU experiences three stages: the sensible heat stage before melting, the melting stage, and the sensible heat stage after melting. The ESU shows a high temperature uniformity in circumferential and axial directions. The temperature difference in the two directions is within 5 °C. A higher MEPCM particle fraction and higher PCM core fraction indicate a higher total PCM content, which results in higher energy storage capacity but slows down the energy storage rate. Carbon fiber fraction with a 10% variation shows a mild influence on temperature response and energy storage. In the consecutive alternate charging and discharging experiments, the latent heat of the PCM can be fully utilized and the system has a nearly constant energy storage/release rate. The stable operation and the high heat transfer rate of the system demonstrates that it is practical in the application for domestic hot water.