Abstract
Storage-type water heating systems have been used widely in residential applications, and it is important to make the sizes of storage tanks smaller for space saving. One of the ways to realize that is to incorporate phase change materials (PCMs) into the tanks and increase the density of stored heat by utilizing the latent heat of PCMs. In this paper, the performance of a water heating system with a storage tank using a PCM is analyzed by numerical simulation. A simulation model is presented for a CO^2 heat pump water heating system, and a numerical study is conducted to compare the performance of the systems with and without die PCM. Through the study, it is shown that the performance of the former system is superior to that of the latter system in terms of both the amount of hot water available and the system efficiency, and how the PCM size affects the temperature distribution in the storage tank and the performance enhancement.
