Thermal Activation Effect of Heat Pipe on Surrounding Rock in Geothermal Energy Utilization

Among the various heat transfer elements, heat pipes are currently one of the world's most efficient, allowing large amounts of heat to be transferred from one end to the farther end quickly and without any external forces through a small cross-sectional area. Using heat pipes in geothermal energy utilization allows a broader range of high-temperature surrounding rocks to be thermally activated, and the efficiency of geothermal energy extraction can be improved. In this paper, a numerical model is established to analyze the effects of different heat pipe arrangements and degrees of clustering on the heat exchange, then the temperature variation is explained by the thermal activation distance and the amount of heat transfer area loss. It is concluded that (i) heat pipes can effectively increase the heat exchange capacity of the lane, and laying a row of heat pipes increases the temperature difference between inlet and outlet water by 25% at maximum; (ii) inclined heat pipes have more minor heat exchange area loss and more substantial heat exchange capacity; (iii) heat pipe clusters received a maximum temperature increase of 156.25%, and when the number of heat pipes used is more than or equal to 5, attention should be paid to the way of arrangement to ensure that the average heat transfer area of heat pipes is more significant than 0.6 m2 to give full play to the heat transfer capacity of heat pipes.