Study On Annual Underground Heat Accumulation Of Ground Source Heat Pump For Residential Buildings

Underground soil is used to absorb and release heat in ground-source heat pump, its temperature is an important parameter to study the system performance, and the running effect is influenced by soil temperature variation. In view of the average soil temperature is reflected by buried pipe return water temperature, and then underground heat accumulation is studied based on the change of return water temperature in this paper. Special researches are listed as follow:Firstly, based on numerical method and analytical method, double-U vertical buried pipes and its around soil transient heat exchange model is established, and buried pipe side return water temperature is obtained. The experiment of winter and transition season is carried out in an residential district of Qingdao. The model of buried pipe is verified by test data and the goodness of fit is high. The average deviation is 3.3%.Secondly, according to actual building structure, the building model was built in DeST platform and the hourly building load is simulated by setting parameters of Qingdao meteorology. The numerical results are regarded as the input parameters to simulate annual operating results. Average simulated heating load is 345kW, it is higher than the test value and lower than the design value.Finally, based on the characteristics of residential buildings, the annual pipe-side return water temperature under different load rates respectively at 100%,70%,50%and 30% are simulated. Return water temperatures are all increased according to the results. It indicates that heat is accumulated around buried pipe. Annual temperature distribution of underground soil is analyzed concretely at the load rate of 70%, and we find that temperature is not increase entirely, but the overlapping result of release and absorb heat. In addition, tight clay and light clay are also simulated.Annual underground heat accumulation of ground source heat pump for residential buildings are analyzed in order to support reference data for system design, and this has some academic value and practical significance to the further application of ground source heat pump system.