Analysis of the Influence of Pipe Diameter on the Heat Extraction Performance of Deep Borehole Heat Exchanger at Different Depths

The heat extraction performance of the deep borehole heat exchanger is affected by a variety of factors such as the depth of the buried pipe, the outer pipe diameter, etc. In order to ensure its efficient operation, it is particularly important to study its influencing factors. This paper establishes a heat transfer model of deep borehole heat exchanger, and uses engineering measurement data to verify the accuracy of the model. Determine the influence of internal and external pipe diameters on the heat extraction performance of the deep borehole heat exchanger under different buried pipe depths, analyze the outlet water temperature and heat extraction of the heat exchanger under different design parameters, and carry out economic analysis. The results show that: when the inlet water temperature is unchanged, the greater the depth of the buried pipe and the larger the diameter of the outer pipe, the greater the heat extraction capacity of the heat exchanger of the deep borehole pipe. When the depth of buried pipe is 3500m, the diameter of outer pipe is 244.48mm and the diameter of inner pipe is 120mm, the average heating cost of deep buried pipe heat exchanger is the smallest LCOH, and the energy benefit is the best.