A module integrated with the phase change material-decanoic acid and copper tube heating by hot air was proposed. Using its one cell as experimental subject, the temperature variation of the phase change material was evaluated using thermocouples. The heat transfer characteristics of the module was acquired by comparing the phase changing process of the horizontally arranged cell with that of the vertically arranged one. The results show that the decanoic acid’s melting rate of the module placed horizontally is higher than the one placed vertically in the same experimental conditions, which provides a reference for the installation of it in practical applications. An improved module, containing S-shaped cooper tube which enhances the natural convection in the outside wall, has better energy storage efficiency.