Numerical Analysis And Study On Diameter Of Buried Tubes Of Double U - Source Ground Heat Pump In Lianyungang Project

This paper analyzes the four nominal diameter of double U-shaped ground source heat pump based on a specific project in Lianyungang, including 50 mm,40 mm,32 mm and 25 mm.The gambit numerical analysis model is set up, using fluent software to simulate heat exchange process of the double U-tube exchanger to analyze the influence of different pipe diameter on heat transfer process and its change rule. Combined with the project in Lianyun gang, this paper analyzes the changes of economic comparison while double U-tube diameter changes.Thus,it provides theoretical guidance for the design of heat exchaner of the project.Firstly, this paper carefully investigates the domestic and foreign literature associated with double U-shaped ground source heat pump to lay a certain theoretical basis. Addtionally, this paper has tested the response of soil heat on the project to obtain the soil thermal parameters needed for numerical simulation. This paper uses CFD to simulate how the four pipe diameter of double U-shaped ground source heat pump operate for one day and ten days and their heat exchange process. This paper analyzes the influence of different pipe diameter on temperature change, heat transfer capacity and thermal influencing radius of the soil. On the basis of this,this paper analyzes the changes of economic comparison while double U-tube diameter changes. Through the analysis and comparison, in the case of constant velocity, the temperature difference between the inlet and outlet of the buried pipe is decreased from 32.4% to 14.37%, but the heat transfer capacity increases from 9.78%-7.07%;in the case of constant flow, both the temperature difference and heat transfer capacity increase slowly. In the two cases above, the thermal influencing radius of the soil increases with the increase of pipie diameter from 1.34%～6.48%.After the final economic analysis, in four kinds of pipe diameter, the initial investment of 32mm buried pipe system is 1.057% lower than the 25mm buried pipe system, but its temperature difference is 32.43% higher than that of 25mm buried pipe syatem. So it will bring more water pump energy consumption, and the host operating efficiency is reduced. After a comprehensive comparison,25mm is a more economical and suitable diameter.Through this study, this paper hopes to provide theoretical reference for practical engineering application of double-U type ground source heat pump, to promote the better development of the GSHP system.