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Numerical study on long-term performance of ground source heat pumps with tunnel lining heat exchangers

Abstract:To investigate the long-term performance of ground source heat pump connected to the mountain tunnel lining heat exchangers in subtropical region,a three-dimensional numerical model for the coupled heat transfer of heat pumps and tunnel lining GHEs was developed under the cooling condition. The validity of the heat transfer model was verified by the measured data of field thermal response tests. Based on a tunnel in Shenzhen,the heat transfer performance of ground source heat pump system connected to the tunnel lining heat exchanger under 10 years continuous operation was calculated and analyzed. The results show that the maximum inlet and outlet temperatures of the absorber pipe in the tenth year are 36.96 °C and 33.46 °C,both of which meet the normal operating temperature range of the heat pump and only increase by 0.06 °C compared with the first year. The minimum energy efficiency ratio(EER)of the ground source heat pump in the tenth year is 4.76,which meets the EER requirement of the ground source heat pump,and the minimum EER only decreases by 0.01 compared to the