Investigation of the Heat Transfer Performance of Multi-Borehole Double-Pipe Heat Exchangers in Medium-Shallow Strata

Abstract

Just as the double-pipe heat exchanger is being utilized in an increasing number of applications, its research content is also deepening. For this paper, based on the air-conditioning cold and heat source project of a building in Handan, Hebei Province, a 300-meter medium-shallow well double-pipe heat exchanger was used for heating and cooling, and a corresponding heat transfer model was established. The changes of parameters such as the inlet and outlet temperature, heat exchange (with and without a temperature gradient), and borehole wall temperature distribution between a single borehole, double boreholes, and four boreholes over one year in medium-shallow wells were simulated and analyzed. By comparing the obtained experimental data and the simulation data, the accuracy of the heat transfer model was verified. This provides a theoretical basis for the further advancement of the project and lays the foundation for an in-depth study of multi-borehole double-pipe heat exchangers.

Heat Transfer Mechanism of Heat–Cold Alternate Extraction in a Shallow Geothermal Buried Pipe System under Multiple Heat Exchanger Groups

“…At present, scholars have conducted a lot of research on the heat transfer mechanism and heat transfer efficiency of single buried pipe groups [5,6]. However, for more efficient heat exchange, multiple sets of buried pipe heat exchangers are usually laid underground [7,8], but there is still lack of research on the winter-summer cycle process with multiple heat exchanger groups. Therefore, it is of significance to explore the heat transfer mechanism of the whole heat-cold alternate process of a shallow buried pipe system (SBPS) in winter and summer, and discuss the influence degree of each development parameter on the heat transfer performance under the condition of multiple heat exchanger groups, which can provide support for the scientific optimization of SBPSs in shallow geothermal system development.…”