Numerical Simulation For Pipe Connection Of Ground Heat Exchanger With Solar Energy Seasonal Storage

Solar-assisted ground-coupled heat pump system(SAGCHPS) combined solar energyseasonal storage system and ground source heat pump together, to realize the shift quarter useof solar energy. The study of system performance concentrated in solar collector andunderground heat exchanger. This paper will research the pipe connection of ground heatexchanger on the impact of soil heat storage and extraction performance. Numerical modelshave been established for both parallel and series-parallel connections of25pipes of groundheat exchanger.This paper has referred to the theory of axial compression model. The25wells have beencompressed200times in the axial, with lateral dimensions unchanged. To build the axialcompression model for25wells, we should change the physical parameters of the fluid andsolid and boundary condition by compiling UDF program. It has been validated that the resultalmost had nothing to do with the compression ratio.In this paper, the influence of level buried pipe and the bending part of the U tube had beenignored. While the series-parallel and parallel connection of the pipes had been completed bycompiling UDF program. Based on the water tank stratification theory, a tank model which isused as a storage heat source has been established. The tank model made the inlet temperatureof the pipe changed over time. Furthermore, the two connecting formats have the same quantityof heat by setting the same start and stop temperature for the tank model.Two buried pipe series-parallel model and parallel model both with tank storage have beenestablished. The two models have been calculated for30days both in the heat storage mode andthe heat extraction mode, in which the two models have the same quantity of storage heat andthe same time for heat removing. By analyzing the evolution of temperature distribution of thesoil, we conclude that it is necessary to taken heat short circuit between pipes, thermalinterference between wells and the nonuniformity of axial temperature distribution into consideration when modeling the soil heat storage performance of ground heat exchanger. Thesoil heat storage performance of the series-parallel connection performs better by comparing theaverage daily heat storage time, average daily heat storage power and thermal storage EER ofthe two connection formats. We got the conclusion that the EER of series-parallel connectionfor heat extraction mode is two times of parallel connection, although it’s heat extractioncapacity of unit depth is17%short than parallel connection format through caculating thequantity of heat remove, EER and efficiency of thermal remove. The results show that, aftercaculating30days for both heat storage mode and heat extraction mode, the performance ofground heat exchanger for series-parallel connection is in favor of seasonal heat storage.