Experimental Study And Hourly Simulation Of Intermittent Operating Conditions Of Ground Heat Exchanger In Sutropical Region

Ground source heat pump has been popularized and applied widely because of its environmentally friendly?energy-saving and environmental protection?cost-effective.The design of the ground heat exchanger is the core of the design of ground source heat pump.Not only the return rate of the initial investment is low,it also lead to permanent destruction of underground temperature field and it's difficult to recover,if the design of the buried tube heat exchanger is not reasonable.So the reasonable design of buried pipe heat exchanger is particularly important.While,the accurate prediction of ground heat exchanger heat transfer performance is the premise of the rational design of ground heat exchanger.But according to current research condition,hourly dynamic simulation research of ground source heat pump system combined with the geological condition and climate characteristics in hot summer and warm winter area is rather few.In this paper,study through experiment and simulate hourly combining with the geological condition and climate characteristics ground heat exchanger-cooling tower coupled ground source heat pump system in the subtropical region,results can provide important reference for the optimal design and research of the ground heat exchanger in hot summer and warm winter.The major research includes following several aspects:(1)Testing conditions of the refrigeration and heating of system to analyze uncertainty of ground heat exchange,and study the influences of ground heat circulating medium flow?depth of underground pipe?running time etc on The amount of heat exchange of unit well depth?COP with heat pump unit and system?the temperature difference of the import and export,explore the best operation mode of the system.After system movement stable,the amount of heat exchange of unit well depth maintained at 47.39W/m around,energy efficiency ratio of unit and system were maintained at about 5.3?3.6,experimental results show that the system has a high running stability and economy.(2)Modeling for the ground source heat pump air conditioning system for Library in hot summer and warm winter area according to the system local geological conditions?climate characteristics?unit parameters?buried pipe?running way etc,simulates long-term intermittent cooling and heating conditions of system through established model,comparing the simulated value with measured value of the amount of heat exchange of unit well depth to verify the correctness of the model,both maximum relative error is 8.6%,while the average relative error is 7%,within the project allowable range,It can be considered that the model is very close to the actual system,the simulation results have a good significance to design and research of ground source heat pump system.(3)Model has been validated under the right conditions,using single factor to simulate and analysis the changes of the ground temperature rise at well bore and the hot and cold load with running time,and effects of well spacing?ground thermal conductivity?thermal conductivity of the backfill material?length on the outlet temperature and the ground temperature rise at well bore,using orthogonal experimental method and analysis of variance to analysis each factor of the ground temperature rise at well bore,under simulated conditions,confidence level of 0.05,the soil thermal conductivity and well spacing significantly affected the ground temperature rise at well bore,a confidence level of 0.01,the soil thermal conductivity significantly affected the ground temperature rise at well bore;factors affecting the ground temperature rise at well bore degree order:ground thermal conductivity>well spacing>length>thermal conductivity of the backfill material.