The effect of groundwater flow on the thermal front created by borehole heat exchangers

Abstract

This paper presents an analysis performed using a coupled TEMP/W-SEEP/W finite element model to consider both the conducive and convective effects of groundwater flow on the thermal regime created by a ground source energy system. The change in the development of the sub-surface thermal regime created by ground source energy borehole heat exchangers caused by a groundwater flow across a site, relative to a scenario where groundwater flow does not exist is examined. Analysis is performed using finite element formulations of both single borehole and multi borehole systems. The results of this work show that even a modest groundwater flow across a site can lead to a significant change in the development of the sub-surface thermal regime. It also shows that groundwater flow can result in implications for: proposed developments incorporating ground source energy systems; nearby existing ground source energy systems; potential future nearby ground source energy systems and the use of established software packages currently used for the design of ground source energy systems in the industry.