The existing enhancement methods for the heat transfer of phase change material (PCM) in domestic hot water tank, such as adding fins and the expanded graphite, can lead to the reduction in the energy storage density of the encapsulation. Additionally, the graphite may settle during the melting process of PCM. To address this issue, a feasible solution is to promote the PCM's melting performance through improving the structure of cylindrical containers, which have been widely applied in domestic hot water tank, thereby taking advantage of contact melting modes without adding additional materials. In particular, an inverted conical container, which has a relatively lower ratio of the top area to the bottom area when compared to the cylindrical containers, has been proposed to encapsulate the PCM with the goal of establishing the contact melting mode between solid PCM and heated side walls when the PCM drops. To evaluate its performance, a mathematical model was developed and validated by the results obtained from a visualization experiment. Based on this model, the melting performance of the PCM encapsulated in the inverted conical container was analyzed and compared with that encapsulated in cylindrical container. The results show that the total melting time of the PCM encapsulated in the inverted conical container is 2 520 s under the same volume (1.74e-04 m3) and height（0.05 m）. It is decreased by 690 s when compared with that encapsulated in the cylindrical container, which indicates the melting performance has improved 21.5%. Except for the contact melting, the natural convection of the liquid PCM also strongly affects the melting performance of the PCM. It is found that the Rayleigh-Bernard convection in the side region results in the decrease of melting performance of the PCM. In addition, an interesting finding is that higher melting performance (i.e.16.7%) is achieved for the PCM encapsulated in the conical container when compared with that encapsulated in the inverted conical container. In this view, the combined usage of conical enclosure and inverted conical enclosure can be appreciated to improve both the heat storage capacity and the melting performance in practical applications.