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Experimental and simulation analysis of geothermal heat pump system

The use of geothermal heat pump systems has spread over the last decades due to its potentials to provide clean energy supply for building’s heating and air-conditioning systems while reducing the associated carbon footprint. This paper describes the design and the post construction performance monitoring of a geothermal heat pump system installed under a three-floor resident house located in Cleveland, OH, USA. The heat pump was installed in shale rock formation. Data from post construction measurement of the geothermal heat pump system between October 2012 and May 2013 were analyzed. The heat pump provided the total energy output of 23021 kW•h. The energy efficiency of geothermal heat pump system is about 4 and it can satisfy the house heating requirement for 87% of the studied period. On the basis of the prototype system, a 3D finite element model was developed on the ground heat exchangers to simulate the complex heat transfer process associated with solid-fluid interactions. A sensitivity analysis was carried out to explore the influence of pipe depth, fluid flow velocity, pipe diameter, thermal properties of borehole refilling material on the performance of the underground geothermal heat exchanger. From the analyses, the key influencing factors on the extracted heat per depth of ground heat exchanger were determined. Recommendations were provided to optimize the design of geothermal heat pump system for both commercial and residential building applications.

Author(s):

Chanjuan Han    
Case Western Reserve University
United States

Xiong Yu    
Case Western Reserve University
United States