Research On Heat Transfer Of Buried Heat Pipes During Geothermal Utilization

Currently, China's total energy consumption has accounted for 1/5 of the total global energy consumption, and energy consumption will maintain to grow in the future. Energy problem has become an important problem to constrain the development of China. How to effectively improve the efficiency of energy use, effective energy conservation has become a major matter in the present. With wide distribution on the earth, geothermal distribution is a renewable clean energy, whose development prospect is broad and utilization value is very high. But how to exploit geothermal smoothly out of the ground has become a major bottleneck in restricting the use of geothermal energy. Adopting the gravity heat pipe to collect the geothermal energy has become a new technology. The geothermal heat pipe is very different from the ordinary gravity heat pipe, whose liquid tank is too deep, and flow resistance of the steam in the pipe is too large. However, due to the deep burying of geothermal heat pipe underground, and indirect observation of the flow of the situation, this paper adopts CFD method to study the flow of geothermal heat pipe internal working fluid.On the basis of literature researches and investigations at home and abroad, theoretical analysis and numerical calculation are combined to establish a numerical heat transfer model through fluid mechanics, heat transfer, computational science, under the law of the numerical simulation of the heat pipe heat transfer. The main research content are as follows:(1) A mathematical model of heat transfer in the porous medium and the super long gravity heat pipe will be established;(2) Numerical simulation research is adopted in CFD software of degeneration of the porous media filled tubes. On the basis of the former research, the circular section of pipeline section shapes are mainly taken into considerations (including the effects on the heat transfer of ellipse cross-section, square cross-section, triangular cross-section), and the various variable cross-section tube axis temperature, pressure, velocity distribution are analyzed. Through comprehensive analysis in the research section of a pipeline shape degeneration with triangular, we can get the conclusion that cross section tube of the comprehensive heat transfer has the best performance;(3) With the adaptation of CFD software in the super gravity heat pipe heat transfer process in the numerical simulation of through carrying on the secondary development of CFD software, C language written defined function (UDF) is combined with software simulation. Simulation results explain why other experimental process in a deep buried gravity heat pipe steam output is less, the heat transfer efficiency is not high, and puts forward the suggestions to solve the problem, so as to enhance the heat transfer and make more efficient use of geothermal.