Research and applications of ground coupled heat pumps for air-conditioning in buildings

Application of ground coupled heat pumps (GCHP) has been popular for commercial buildings in China in recent years for space heating in winter and space cooling in summer. Problems of lower COP and unbalanced heat extraction and heat injection could cause poor economic performance and under-sizing of the engineering projects. In this presentation, the general situation of the GCHP applications will be introduced first and our research in this area will be reported including our investigations on heat and mass transfer of vertical and inclined borehole ground heat exchangers (GHE), hybrid GCHPs, GCHPs with foundation pile GHEs and solar added GCHPs. Analytical simulation and experimental results of the heat and mass transfer surrounding the different GHEs will be presented. The analytical heat transfer model for foundation pile GHEs with groundwater advection will also be included. Our studies demonstrate that the GCHPs could save energy or not depending on different applications. Detailed performance simulations should be done at planning stage of each engineering project.