Influence of soil moisture transfer on performance of ground heat exchangers in summer

Based on the one-dimensional linear heat source theory, develops a heat and moisture transfer linear heat source model considering the variety of temperature and moisture content in soil. Simulates the variety of temperature and moisture content in soil around buried pipes in summer running condition. The results indicate that the incidence of moisture transfer in soil is mainly in the borehole. Compares the simulation results with the experimental results of one-dimensional heat and moisture transfer, finds that the two results have comparatively high similarity. Obtains a modified fitting formula for the capacity of the ground heat exchanger from common linear heat source model with different initial mass moisture contents in soil. Calculates and estimates the ground heat exchanger capacity in different depth of soil with weighting method, concludes that the difference of heat exchange rate caused by soil moisture transfer could be ignored when the average underground water level is higher than -20 m in summer.