Numerical simulation of a low-cost efficient ground heat exchanger coupled with heat pump

The Ground-coupled Heat Pumps (GCHPs) with a vertical ground heat exchanger use the soil as winter heat sources and summer heat sinks via ground heat exchangers (GHEs). To exploit effectively the heat capacity of the ground, a heat-exchanger system has to be designed and constructed to facilitate heat transfer to/from the ground. In the UK, among the key barriers to the technology adoption is the high installation costs of GHEs. The overall aims of the project is to investigate the technical feasibility of a low cost heat exchanger that would enable vertical closed loop Ground Source Heat Pump (GSHP) to become economically viable for space heating and cooling in the residential applications. The performance of a closed loop GSHP system depends on local geological conditions. Under the climatic conditions of Nottingham in the UK. In order to study the fluctuations of the ground temperature with depth and the physical parameters of GHEs, one has developed the most typical models, and simulated with Engineering Equations Solver (EES). The results shown that the ground temperature is the key parameter describing the potential of the thermal energy in the soil. The diameter of the GHEs and the materials type did not have large influences on the temperature lift across the heat pump (HP), i.e., the difference between the source temperatures (Tin) and the load temperatures (Tload) has directly influences both Coefficient of Performance (COP). Because of the high thermal inertia of the soil in Nottingham, the temperature fluctuations at the surface of the ground diminish as the depth of the ground increases. The annual temperature variation of the ground at a depth of 10m is between -3 to 14°C. During the year, the earth temperature beyond a depth of 1 m is sensitive to the air temperature and solar radiation and the annual fluctuation of the earth temperature extends to a depth of about 10 meters and the COP of ~ 2.5 – 4.