Simulation study on charging performance of the latent energy storage heat exchanger with a novel conical inner tube

The application of a latent heat thermal energy storage (LHTES) system can effectively solve the problem of the mismatch between the energy supply and demand. However, most studies focus on the traditional cylindrical configuration with a low heat storage rate, which limits the wide application of LHTES systems. The configuration optimization of a vertical shell-and-tube LHTES unit is carried out in this paper to enhance heat storage rate, and the effects of cone angle values (0-101 in the conical shell and conical tube configurations on the heat storage performance are explored by numerical simulations. The results show that these two kinds of conical configurations both significantly improve the melting rate of the phase change material (PCM) compared with the cylindrical unit. However, when the cone angle is the same, the heat transfer enhancement effect of the latter is found to be superior to that of the former. Moreover, the complete melting time is shortened by 46 % as the cone angle of the inner tube increases from 0 degrees to 10 degrees. More importantly, a novel conical tube configuration design is proposed to eliminate the hard-to-melt zone at the bottom of the LHTES unit with the conical tube, then the effects of different tilting heights (60-170 mm) and bottom annulus distances (0-10 mm) are investigated. The results demonstrate that the melting rate increases with the increase in the tilting height, but the increased amplitude of that gradually reduces. Besides, the average heat storage rate shows a trend of first increasing and then decreasing with the increase in the distance of the bottom annulus. When the bottom annulus distance is 2 mm, the average heat storage rate reaches the maximum value, which is 94.84 W. The research results can provide a reference for the engineering design and configuration optimization of the vertical shell-and-tube phase change heat exchanger.

Automated summary

This paper focuses on the configuration optimization of a vertical shell-and-tube latent heat thermal energy storage (LHTES) unit to enhance heat storage rate. It explores the effects of cone angle values on the heat storage performance and proposes a novel conical tube configuration design to eliminate the hard-to-melt zone. The research results provide reference for engineering design and configuration optimization.