RESEARCH ON HEAT TRANSFER CHARACTERISTICS AND BOREHOLE FIELD LAYOUT OF GROUND HEAT EXCHANGERS TO ALLEVIATE THERMAL ACCUMULATION WITH GROUNDWATER ADVECTION

The heat transfer performance of ground heat exchanger is significant to the ground source heat pump. The soil thermal parameters, the groundwater advection and the different borehole field layout are important factors to affect the performance of ground heat exchanger. Therefore, the influence of groundwater advection velocity, soil physical parameters and different borehole field layout on the soil temperature distribution and evolution around the ground heat exchanger has been analyzed and studied with unbalanced seasonal thermal load based on the moving finite line heat source model with groundwater advection. The results show that the heat accumulation is easy to occur as the time develops when the groundwater advection is taken into consideration. No matter what type of geological condition is employed, a reasonable borehole field layout can effectively avoid heat accumulation problems under the condition of keeping the same amount boreholes without changing the original ground area. The borehole field layout dispersed along the center line of the advection and concentrated in the advection downstream relatively can effectively reduce the heat accumulation.