Numerical Model For Applicability Study Of Ground Heat Exchanger With Solar Energy Seasonal Storage

Solar heating system with seasonal heat storage(SAGCHPS)combined solar energy seasonal storage system and ground source heat pump together, to realize the seasonal use of solar energy. In the paper, we are aimed at studying the applicability of different numerical models of ground heat exchanger which all based on SAGCHPS, this thesis sets up equivalent single tube numerical model(EQST model)of ground source heat pump, three-dimensional axial compression numerical model(3DAC model), and three-dimensional axial compression and stratification numerical model( 3DAC&S model); in order to research thermal interference phenomenon between tubes of ground heat exchanger, the paper sets up ideal model of ground heat exchanger to measure the degree of short circuit between buried tube. When build 3DAC&S model, according to temperature conductivity of soil the ariticle layers the soil outside drilling into five or ten along the longitudinal, at the same time, compares them, the ariticle finds out that if the system run for a long time, the deviation of them will be lower than 0.29%. Taking the preparatory work and so on into account, the established stratification model in this ariticle makes soil along the axial into five layers.Based on solar energy seasonal storage system in energy consercation centre of Hebei University of technology, located in beichen district of Tianjin, The dissertation makes data from experiment fitting for inlet boundary of FLUENT software in turn to experimental verify equivalent single tube numerical model of ground source heat pump, three-dimensional axial compression numerical model as well as three-dimensional axial compression and stratification numerical model, the result finds out that three models of ground heat exchanger all own practical significance, compared with two other models, 3DAC&S model is more close to actual.Under different conditions, the paper as three-dimensional axial compression and layer numerical model for the standard conducts deciation comparion to study applicability of models. The final results show that: EQST model is suitable that inlet temperature of U type tube is 40℃,50℃,60℃, 80℃or inlet velocity of U type tube is 0.3m/s,0.5m/s at beginning of the system runtime; between 3DAC model and 3DAC&S model there exsit constant deciation; 3DAC&S model is fit all systems. In addition, the paper as the temperature distribution between U type tubes the criterion research thermal interference phenomenon between tubes of ground heat exchanger. The results show that: the greater inlet temperature of U type pipe, the smaller inlet velocity, the more likely to happen thermal interference phenomenon among the branch pipe of U type tube; the greater thermal conductivity of backfill material as well as soil, the more likely to happen thermal interference phenomenon among the branch pipe of U type tube.