管壳式相变蓄热器的蓄释热过程性能分析

[Objectives] The influence of different placements of phase change heat exchangers on the phase change process was investigated, and the simplified mode of multi-tube heat exchangers was further analyzed. [Methods] Based on the enthalpy-porosity method, a calculation model for the melting and solidification process of the shell-and-tube paraffin heat exchanger was established, and the phase change process of paraffin outside the single-tube was investigated under horizontal and vertical placements. The effects of single-tube heat exchanger and multi-tube heat exchanger with straight and staggered rows on the melting and solidification process were compared, respectively. [Results] Full melting time of horizontal single-tube heat exchanger is 18% shorter than that of vertical, but the difference of full solidification time between the two is not significant. Unlike the melting process, the solidification process uses heat conduction as the main mode of heat transfer, so it is relatively slow, and the full solidification time is increased by more than 20% compared to the same period of full melting time. The time required for the melting and solidification process of multi-tube heat exchanger is slightly longer than that of the single-tube heat exchanger, but its increase in time is not more than 10%, and its melting and solidification rate curve is basically consistent with that of single-tube. Through further study, it is found that when the volume of paraffin wraps around each tube in the multi-tube heat exchanger and the wrapping method is the same, different arrangement methods of the multi-tube heat exchanger would not affect the melting and solidification process. [Conclusions] Compared with the vertical placement, the horizontal placement can effectively enhance the melting rate of paraffin outside the single-tube, and the enhancement effect of the melting process is more obvious than that of the solidification process. In addition, when analyzing the performance of the melting and solidification process of the multi-tube heat exchanger, the single-tube or part of the periodic tube can be used for simplification.