Application of co-axial heat extraction to the study of Geothermal System

• Main Authors: Tzu-Ching Chiu, 裘子慶
• Other Authors: 何正義
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/99vdhe

碩士 === 國立宜蘭大學 === 機械與機電工程學系碩士班 === 107 === In this paper, the numerical simulation analysis software ANSYS is used to investigate the feasibility of taking heat from the coaxial heat extraction and the influence of various conditions on the coaxial heat extraction. In the study, computational fluid dynamics (Computational Fluid Dynamics) and structural mechanics are used to couple each other, and the coaxial heat extraction tube is analyzed by fluid-solid coupling. In the simulation analysis of the flow field of the coaxial heat pipe, the material of the pipe at the flow rate of the water inlet and the temperature gradient of the formation must be taken into consideration, as well as the setting of the turbulence model. Then, the distribution of the pressure during the operation of the coaxial heat pipe is calculated and the inner pipe is calculated. The fluid-solid coupling analysis calculates the distribution of the stresses experienced by the inner tube of the coaxial heat pipe during operation. The results of this simulation show that the temperature of the outlet of the coaxial heat pipe is significantly higher than the temperature of the water inlet. Therefore, it can be said that the coaxial heat pipe can successfully bring the heat in the depth of the ground to the surface, so it can be said that the heat of the coaxial heat pipe is taken. It is feasible and successful, and the best condition obtained is that when the inlet flow rate is 0.55 m/s, the heat transfer tube with a heat transfer coefficient of 0.06 W/ mK is used, and the heat exchange obtained by the assumed geothermal gradient 2 is selected. The water temperature in the zone can reach 134 °C, and the water temperature in the outlet can reach 111 °C. The geothermal gradient is the most important parameter for the coaxial heat pipe, and then the material used for the inner tube of the coaxial heat pipe, and finally the flow rate of the water inlet. However, in the case of subsequent fluid-solid coupling results, the equivalent heat stress of the coaxial heat-receiving pipe at the inlet is 0.55 m/s, 1 m/s and 2 m/s, and the equivalent stress is 13.4 MPa. There is no permanent deformation.