Study on a PCM heat storage system for rapid heat supply

A thermal energy storage system employing phase change material (PCM) FNP-0090 (product of Nippon Seiro Co. Ltd.) for rapid heat discharge was studied numerically and experimentally. In the numerical studies, the PCM was encapsulated in four different capsules (sphere, cylinder, plate and tube) for investigating the effects of geometrical configurations. The effects of the capsule diameter and shell thickness and the void fraction on the performance of the heat storage system were also investigated. The experiment was conducted by using a commercial plate heat exchanger as the heat storage tank. It was found that the spherical capsule showed the best heat release performance among the four types of investigated capsules, whereas the tubular capsule with low void fraction was not ideal for rapid heat release of the thermal energy stored in the PCM. The heat release performance decreased in the order of sphere, cylinder, plate and tube. The numerical results and the experimental data agreed within 10%.