Heat transfer analysis of underground hear exchangers under coupled thermal conduction and groundwater advection conditions

To determine extent of the effect of groundwater advection on Utype vertical underground heat exchangers, based on a mathematics model considering thermal conduction and groundwater advection, utilizes an overall solution to obtain the whole temperature field including fluid in pipe, pipe wall and surrounding soil. The results indicate that groundwater flow has notable effects on original temperature field and that the higher the groundwater velocity is, the larger the effect is. Then through calculation of several cases with different soil type, concludes that the thermal conductivity of soil has more influence than water content.