<p>Shell and tube heat storage technology is considered an effective means to address temporal and spatial mismatches in renewable energy utilization. However, its application is limited by poor heat transfer performance. In this study, an elliptical tube was introduced in the shell and tube heat storage unit, and the thermal storage performance was investigated and compared with circular tube by numerical simulations. The superiority and reliability of elliptical tube thermal storage units were validated, and the effects of heat transfer fluid (HTF) flow velocity, heating temperature, and the angle between the major axis and HTF flow direction on heat transfer capacity were elucidated. It was demonstrated that the introduction of elliptical tube can reduce the melting time of molten salt-based phase change material (PCM) by 63.11% and decrease pressure drop by 95.19% compared to circular tube under the equal cross-sectional area. In addition, it is found that the increase of the HTF velocity is helpful to promote the heat transfer, but also results in higher pressure drops and energy losses. As the heating temperature increases from 425 K to 445 K, the melting time of the PCM can be reduced by 63.2%. The angle between the major axis of the elliptical tube and the HTF flow direction was also identified as a critical factor, with angles between 30° and 60° providing an optimal balance between phase change time and pressure drop, making it an ideal choice for the improvement of heat exchange efficiency and the reduction of energy consumption.</p>