Research On Underground Heat Exchanger In The Ground-source Heat Pump Considered Fluid-structure Coupled Heat Transfer

The Ground-source heat pump system with high efficiency, environmentalprotection, energy saving features have been paid great attention in recent years. One ofthe key techniques for GSHP popularization and application is to solve the heat transferproblem between buried pipe and soil. So it has great value to perfect heat transfermodels for the ground heat exchangers to simulate the actual heat exchange process.Simulating3D fluid flow and heat transfer of double U-tube is done in this paper，which have no geometry simplification comparing with the existing simplified model inthe simulation. Real simulation of this complex heat transfer process will be doneincluding the convective heat transfer between liquid and the inner surface of tubes, theheat transfer between outer surface of the tubes and the backfill material, the thermalconductivity between backfill material and the soil, and the heat conduction of the soil.There are some contents in this study,1. A3D fluid-solid coupling model was built to have a simulation of the heattransfer between the U-tubes and the soil under exothermic conditions. We can get thetemperature distribution of double U-tube horizontal and vertical directions, andextracts out the unit depth heat exchange variation of double U-tube which changingwith time.2. Contrast the pipe outlet temperature and the borehole wall temperaturemeasured from thermal response tests with simulated from the numerical simulationshows that, the average error is4.9%and3.7%,which verify the correction of theunderground heat exchanger heat transfer model which has been established.3. Makes comparative analysis of the validated model and the existing finitelinear heat source model, and makes numerical correction according to the simulationresults on the line source model.4. Sets up the three-dimensional model of hole group on the ground source heat pump heat exchanger, simulates the heat transfer characteristics of hole group onground source heat pump system.The research on GSHP ground heat exchanger in this paper can be applied andprovides guidance to practical engineering.