Soil heat and moisture properties under thermal effect of heat transfer of horizontal ground-coupled heat exchanger

The different soil moisture content is one of the major factors influencing on the thermal conductivity of soil and further impacting on the efficiency of ground-coupled heat exchangers (GCHE). Sandy soil container experiment results show that soil water migration is impacted by heat transfer of the horizontal GCHE. The temperature gradient is the driving force. Under the heat extraction condition, water transfer can be neglected. Under the heat rejection condition in summer, heat and water transfer is coupled and water migrates from the tube wall towards the far field along the horizontal and vertical direction.