Simulation and experimental validation of soil seasonal thermal storage characteristics by air-U tube system in severe cold zone

In order to solve the problem of the soil temperature decrease year by year around the ground heat exchanger due to long-term operation of ground-source heat pump in severe cold area, presents an idea of air-soil seasonal thermal storage based on the existing ground-source heat pump system, and develops the unsteady-state heat transfer models of outdoor air heat exchanger and vertical U-tube heat exchanger. Simulates and analyses the thermal storage characteristics of soil under the conditions of the three thermal storage modes and four buried depths. The results show that the energy efficiency ratio of thermal storage changes from 8.1 to 17.0. From a comprehensive comparison, concludes that heat storage is more economical and efficient by adopting 50 m buried depth and the second mode. Verifies the model by experiments.