Performance Characteristic Analysis And Experimental Study Of Moderate-Buried Double-U Tube Ground-Source Heat Pump System

GCHPS is widely used in commercial and residential buildings due to its relatively small resource constraints, high safety and stability, especially in Beijing.At present, the application rates are 35%. But there neither basic data of the actual project operation nor mature design for the reference about this system in China.The majority of experimental researches for the engineering practiceare are limited to the analysis of a single borehole and deep-buried tube.They hver little consideration about the rationality of system operation and the complexity of the ground formation etc.Therefore, this study discuss the moderate-buried GCHPS which used in a park management office building in Beijing Olympic Forest Park, and a 1:1 mode GCHPS experimental platform which is on line, continuous and real-time is set up. Meanwhile the heating and cooling performance characteristics of this system are monitored long-term to provide basic data. The key study combines with theoretical and numerical simulation method is performed as follows:Firstly, the conception and composition of moderate-buried GCHPS are introduced.The main factors which influence the heat transfer and flow characteristics of ground heat exchanger are understood by the analysis of heat transfer theoretical model Secondly, taking a typical moderate-buried GCHPS as an example, and dicuss the building load characteristics by DeST sofeware and the experimental results.Thirdly, analyzing the flow velocity, the soil thermal conductivity, the initial ground temperature and borehole depth influence the moderate-buried GCHPS during the system stably operate. And also discuss the problem of the whole year building loads and the accumulative quantity of heat or cool.Fourthly, based on the measured data and the engineering thermodynamics, researching the building loads, evaporating temperature, and condensing temperature influence the performance characteristics of ground source heat pump.Finally, analyzing the factors such as flow velocity, soil thermal conductivity, fill thermal conductivity, inlet temperature of the source side, borehole depth and the borehole spacing etc through numerical simulation software TRNSYS, which have great impact on the heat transfer performance of the40-meter-deep ground heat exchangers in winter and summer. Meawhile, the main design issues of GCHPS are understood, and a viable design methodology is established to optimize the typical building which is selected.