Heat transfer characteristics of ground heat exchangers under soil freezing

Taking the soil texture of Harbin as the research object, based on the similarity theory, sets up an experimental platform for low temperature heating of ground heat exchangers, and studies the effects of different initial soil moisture content and porosity on soil freezing range, heat transfer performance of buried pipes and COP of heat pump units. The results show that when the initial soil moisture content is in the range of 0 to 40%, the higher the moisture content, the smaller the freezing range of soil on the buried pipe side, and the better the heat transfer performance of the heat exchanger, especially when the moisture content increases from 0 to 10%. When the initial porosity of soil increases from 0.16 to 0.38, the heat transfer performance of the heat exchanger is obviously improved, and when the porosity increases from 0.38 to 0.47, it has little effect on the heat transfer performance of the heat exchanger. When the initial soil moisture content is 40% and the porosity is 0.47, the COP of the ground-source heat pump unit can reach 3.19.