Using Ba(OH)2·8H2O as phase change material (PCM) and water as heat transfer lfuid (HTF), we numerically simulated annular ifnned-tube heat exchangers. In order to measure and analyze the impact of parameters in the heating/cooling process, temperature changes of different monitoring points, ifn widths, and ifn pitches as key parameters were considered and applied. The experimental results show that the heat exchange process can be divided into three stages within a certain time. The faster heat transfer rate is associated with the greater temperature difference between PCM and HTF. Furthermore, ifns width and pitch affect dramatically the heat charging/discharging rate. The large ifns width or small ifns pitch is beneifcial for extending the heat exchange surface, leading to improve heat transfer efifciency.