Studying the effect of borehole spacing on the thermal performance of ground heat exchanger

Abstract

Future generations are going to suffer energy and environmental problems through this century due to fossil fuel resources depletion and global warming of the earth. Low Temperature Geothermal Energy (LTGE) as a sort of renewable clean energy resources represents a hope to overcome these problems. LTGE systems are generally used for space heating and cooling purposes. Soil acts as a Heat Exchanger (HE) in ground coupled LTGE systems. Ground Vertical Heat Exchanger (VHE) is considered the most efficient as its expected running costs are less than conventional air conditioning costs by about 35%. Study of the effect of ground water flow (GWF) on the heat transfer from the vertical heat exchanger taking into consideration different arrangements of multiple boreholes with the suitable spacing between boreholes plays an important part in the successful design of the ground heat exchanger. In this study six models were established starting from single borehole model to six boreholes model to get the optimum dimensions of the boreholes and the optimum spacing between boreholes if they are arranged in a parallel or staggered arrangements taking into consideration the effect of GWF if it was available.