Simulation Of Ground Temperature In Gshp System Based On Dynamic Load

China is the second largest energy consumer in the world. In China, building energy consumption has increased over 10% each year for the last 20 years and now represents 25-40% of all energy consumed, especially for HVAC. Ground Source Heat Pump (GSHP)systems are the cost-effective space conditioning systems available today. Vertical U-tube heat exchangers are the most widely used heat exchangers for large GSHP systems.In this thesis according to the heat transfer characteristics of single vertical ground U-tube heat exchanger (GHE), the transient heat transfer model was built, and then by comparing the data of experiment with the data of theory, the model was verified right. The soil temperature distribution surrounding the buried heat exchangers under different operating condition of GSHP was simulated with commercial software-Fluent. The result shows that the soil temperature variation in different depths but the same radial distance is not obvious, while the change is different with the different radial distance. The change of temperature is dramatic near the ground source heat exchanger, and the heat interference coefficient is 0.92 at r=0.5m, however, the heat interference coefficient is 0.8 at r=2m. Because of the thermal inertia the soil temperature recovering effect would lag behind in farther radial distances. At the beginning of recovery period, the soil temperature at r=0.5m begin to decline at once. While the soil temperature at r=1.5m and 2m keep on rising at the initial 25 days, and begin to decline then. The thermal inertia plays an obvious part at r=1.5~2m. Furthermore the far field radius was discussed, and a numerical expressions withτandαas variables was given. Then the heat transfer performance of GHE under different operational modes was discussed. The energy consumption of a real building located in Tianjin was simulated by Energyplus. The pipe spacing of 4.5m/5m/5.5m/6m was studied and the result shows that the pipe spacing of 5.5m is better for efficient operation.At last adopting the method of technology and economic analysis and using the objective function based on the sum of capital cost and running cost, discuss whether ground source heat pump system is economical compared with the conventional air condition system. The thesis elaborated the meaning of analyzing sensitivity of LCC in GSHP systems and the cause led to the uncertainty.I wish the work in this thesis can conduce to optimum design and efficient operation of GHE in GSHP systems.