Abstract: This work is motivated by the following two aspects. First, replacement of coal firing to electrical heating has become an effective means to achieve clean heating in the north part of China to combat increasingly serious environmental problems. Second, China's annual use of waste heat, especially in the medium and low temperature ranges, is still inadequate. For both the aspects, the phase change material-based heat storage technology has a great role to play. This article aims to compare heat exchangers consisting of phase change materials. First, a qualitative comparison was made between plate, shell-and-tube, heat pipe and other specially designed heat exchangers (heat storage bricks/balls). Numerical simulations were then carried out using a two-dimensional phase change material melting model for shell-and-tube and plate heat exchangers with the same heat exchange area and boundary conditions. The results showed that the shell-and-tube heat exchanger took about 6 hours to completely melt, and 8.5 hours were needed for the plate heat exchanger mainly due to the difference in the arrangement of the heat exchange tubes/plates. However, the plate heat exchanger is still regarded to have a great potential due to more compact structure, simpler manufacture process and easier to assemble/disassemble, and easier modularization for scale-up.

Key words: phase change heat storage, heat exchanger, contrastive analysis