Underground Heat Transfer Analysis And Engineering Application Of Based On Seasonal Solar Thermal Storage Underground Pipe

The thesis proposes the program and control strategy of traditional ground source heat pump systems and solar seasonal heat storage system, it sets up corresponding model in TRNSYS system and gives the soil temperature which changes over time around the underground heat exchanger of two systems.We set parameters of the system in the model, the initial temperature of the soil which is 15.2 ℃. Firstly the simulation system operated for 1 year and 20-year soil temperature changes over time, the results of analysis is that the traditional ground source heat pump system from the first to the second quarter of refrigeration heating season after the end of the run, the minimum soil temperature is 14.27℃, seasonal solar thermal storage system is 15.03℃, the soil temperature is higher 0.76 ℃. Both systems run for 20 years the lowest temperature of ground source heat pump system is 12.9 ℃, the lowest temperature of the seasonal solar thermal storage system is 15.51℃, the temperature difference between the two systems is 2.61℃. The soil mean temperature of seasonal solar thermal storage system is rising, conversely source heat pump system shows a downward trend.At the same it analyzes the data of underground pipe coupled heat pump and seasonal heat storage system performance in one year. It reaches that the overall temperature of a seasonal solar thermal storage system in one year is higher0.55℃ than soil temperature traditional ground source heat pump system after one year.For practical engineering it respectively tests geothermal test wells, and geothermal heat hole test wells and solar recharge hole test and obtains a large number of measured data. The analysis shows that:the soil temperature trends of different depths in same drilling is consistent, the soil temperatures of different buried deep are different, the deeper the depth of the higher temperature. At the same depth the temperature of solar 2# is highest, followed by heat hole 22#, ground temperature observation wells 33# is lowest. Comparing with traditional ground source heat pump the seasonal solar thermal storage system allows the soil temperature elevate, temperature remained at 0.8℃. The temperature of solar 2# is above 22# at the same time, and the temperature fluctuations of reinjection borehole is less than the volatility geothermal heat hole.It analysis and compares the simulation and measured data a found:Analog data in the transition season shows slow upward trend and more and more slow upward trend, the measured data of soil temperature transition season showed a downward trend, simulated data and measured data vary greatly. It explains ground heat exchanger model matching with actual heat lower. This behavior is mainly due to ground heat exchanger model is a simplified heat transfer model which can not reflect buried complicated geological conditions inside the region in the model, and the actual groundwater is rich in borehole region, water runoff generated a great impact on the heat transfer process.Research and experimental data show that:the ground temperature field value of solar seasonal heat storage system based on underground pipe is higher than the traditional ground source heat pump temperature, temperature of simulation is higher 0.55 ℃.temperature of actual is higher 1℃. It indicated that after the conventional ground heat coupled heat pump system added solar thermal, soil temperature significantly increased. The solar energy put into the soil can increase underground storage underground regenerator heat as a heat source for building air-conditioning end in winter. It can reduce the unbalance between winter extraction and summer exothermic heat of ground source heat pump and help to improve the utilization of renewable energy. At the same time it can help solve the problem of heating in cold and severe cold areas, reduce the chance of occurrence of fog and haze.