The Research On Experiment And Numerical Simulation Of Air-to-Earth Heat Exchanger With Concentric Tube

Air-to-earth heat exchanger (ATEHE) takes the soil as heat source in heating and heat sink in cooling mode. The soil temperature is higher than the air temperature in winter and lower in summer, so it can be used to heat in winter and cool in summer. The use of ATEHE also can reduce the wastage of coal and save oil and nature gas, which will help the country adjust the energy structure and reduce the amount of exhaust gas released to protect the environment and achieve the goal of sustainable development. So the ATEHE is an efficient, economic and green way for heating and air conditioning, and has developing potentialities and vast prospects.The common air-to-earth heat exchanger is horizontal tube. In our country there are so many people that the area of soil is relevantly rare, so the vertical tube can never be neglected. Hereby, I combined the concentric tube mode in ground-coupled heat pump, constituted three-dimension numerical models under different conditions to simulate the heat transfer and flow in concentric tube, the heat transfer between concentric tube and soil and the soil temperature field. To increase work efficiency and adapt the trend of numerical computing, I used the GAMBIT, a software for constituting mathematical models, and the FLUENT, a software for numerical computing, to achieve a numerical model.The main objective of research is to guide the practice, so this paper has two key points of research: the first is to compute outlet air temperature of concentric tube and the temperature field of soil under different working models; the second is to get the influencing effect to outlet air temperature by different factors, such as the inlet air velocity (wind amount) and temperature, the properties of soil, the diameter of concentric tube, the flow ways and the length of concentric tube. I get many data of outlet air temperature of the concentric tube, and temperature field of soil by numerical computing. By thoroughly analyzing the data we can offer some reference in ATEHE of concentric tube mode designs.According to our experiment platform, we did some survey, and compared the simulation value with the test value which is obtained in our experimence, it's an essential progress.For the condition limited, the paper only simulates and analyzes heat exchanging course of the dry air and makes comparison between theoretical and the surveying results, the study on heat exchanging course of the wet air also needs to be done further.