Study on Soil Temperature Recovery Prediction Model of Ground Source Heat Pump

Establishing an accurate model and studying the soil temperature recovery characteristics of the ground heat exchangers under intermittent operation is the key to formulate the operation strategy of a ground source heat pump system under intermittent operation or composite ground source heat pump systems. In this paper, based on the analogy idea of the thermal resistance–capacitance model, the heat balance network equations between buried pipe, backfill material, and soil are constructed, and a model that can quickly and easily predict the recovery of soil temperature is proposed, and the soil temperature change during the intermittent operation of the system is predicted. By comparing the predicted value of the soil temperature change in each layer during the intermittent period of the system under the model proposed in this paper with the simulated value of the stratified heat transfer model which has been verified by the actual engineering measured data, it is concluded that in the 150 h intermittent recovery period, the relative error of the soil temperature recovery degree between the two is less than 10% in most of the time. Therefore, the model proposed in this paper can accurately predict the change of soil temperature in the intermittent period of buried pipe heat exchanger and provide a reference for the design of operation control strategy of buried pipe ground source heat pump system.