南方能源建设 (Sep 2021)
Research on Enhancing Heat Transfer Performance by BTES Hot and Cold Partition
Abstract
[Introduction] Borehole Thermal Energy Storage (BTES: Borehole Thermal Energy Storage) refers to a borehole closed cycle system that uses the heat capacity of underground soil, rocks and water to store energy. The main feature is the use of cold and hot partitioned layouts and intelligent control methods. Innovative development and utilization combined with domestic geology. In order to study the feasibility of using cold and hot zones to improve the heat transfer effect of buried pipes, a single U-shaped buried pipe heat exchanger borehole was established based on the theory of porous media heat transfer, energy conservation, and finite length non-moving line heat source model. Internal and external mathematical models are analyzed and verified by numerical simulation methods. [Method] Based on the common soil cold and hot accumulation phenomenon, by changing the order of the medium in the pipe flowing through the two divided areas, it becomes passive to prevent and control cold and heat accumulation In order to actively deploy energy storage for cross-season utilization, so as to actively generate cold and hot accumulation energy storage in the two divided areas, which are defined as "cold zone" and "hot zone". [Result] After numerical simulation analysis, the phenomenon of thermal accumulation occurs The heat exchange rate of the "hot zone" during the heating period increases year by year. As far as the maximum heat exchange rate is concerned, the second year will increase by 319 W compared to the first year, and the third year will increase by 308 W compared with the second year; cold accumulation occurs. The amount of heat exchange in the "cold zone" during the refrigeration period increases year by year. In terms of the maximum heat exchange rate, the second year will increase by 209 W compared with the first year, and the third year will increase by 198 W compared with the second year. [Conclusion] The above results show that this method can enhance the heat transfer effect of the buried heat exchanger. The alternate use of the two areas during the heating period and the cooling period not only effectively solves the energy efficiency degradation caused by the imbalance of cold and heat of the ground source heat pump system, but also improves the heat exchange effect of the system while reducing the perforated space.
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