Thermal performance and ground temperature of vertical pile-foundation heat exchangers: A case study

To assess the geothermal energy for a district heating and cooling system in Shanghai, China, a case study of ground heat exchangers for a ground-coupled heat pump (GCHP) system is presented in this study. Several types of vertical pile-foundation heat exchangers selected are intercompared to determine the most efficient one. Based on a series of performance tests, experimental data of single pile-foundation heat exchanger are presented. Heat transfer performance is also evaluated by numerical method, which couples heat convection and conduction through water in pipeline, concrete pile and soil. It is further used to investigate five-year changes in the ground temperatures. Numerical results under two imbalance ratios between cooling and heating load are analyzed to evaluate the potential of geothermal energy in the present application. The present study is aimed to provide guidelines for better design of large-scale GCHP in a district heating and cooling system in Shanghai.