Phase change thermal storage devices can effectively solve the shortcomings of solar energy such as intermittency and uncertainty, and realize the efficient use of renewable energy. However, the low thermal conductivity of phase change materials makes it a research priority to increase the melting rate of heat storage units. In this paper, the melting performance enhancement of the phase change thermal storage device is investigated. A numerical model is constructed for the phase change process of the device at different inclination angles and heating boundaries, and parameters such as the complete melting time, the melting fraction, the phase interface and the temperature fields are discussed. The results show that the phase change heat storage rate is optimal at 90° inclination, which reduces the complete melting time by 14.05% compared to 0° inclination. In addition, the increase of inclination angle not only increases the melting rate, but also reduces the area of refractory region and improves the melting uniformity.

Keywords: Phase change materials, Melting properties, Inclination, Heat source, Numerical simulation.