The Numerical Simulation Of Heat Transfer Process And Structure Optimization For Tubes With Low Fins

Energy is an integral part in the daily lives of people for production and subsistence. Theenergy industry has become the arteries of the national economy for a country since theIndustrial Revolution. However, the energy crisis caused by the excessive consumption ofenergy has already restricted the economic development and social progress in recent years.Focusing on new energy development and exploring energy-saving way have become theconsensus of countries around the world.The paper selects the tubes with low fins which are used in condensers as the researchobject, which aims at improving the heat transfer efficiency. The two-dimensional modelwhich the refrigerant(R22) flows in tube and the air flows outside is established by ANSYS,and the author analyzes its fluid-structure interaction simulation by using the fluid heattransfer analysis module which is called ANSYS FLOTRAN CFD,. Orthogonal experimentsare performed to study the distribution of the flow field and temperature field to the heattransfermation process.The following conclusions are drawn from the analysis on the heattransfer theory and fluerics theory, the heat transferring performances of finned tubes aresignificantly better than that of the smooth tube with the same heat flux; the temperature dropof the fluid which flows in finned tubes nearly double than smooth tube within the process of100mm; the fins’ structures are affected significantly on finned tubes’ heat transferringperformances, namely, the fins’ pitch makes the biggest influence on it, the fins’ height takesthe second place and the fins’ thickness takes the third. In specified areas,the heat transferringperformances are enhanced with the increasing of fins’ pitch and height, while weakened withthe increasing of thickness; the structures of fins make big influence on the pressure dropoutside and the fins’ height effects significantly. Besides, the pressure drop outside willincrease with the increasing of fins’ height and pitch.The optimization of the fins finned tubes aims at obtaining more transferred heat with thecost of minimum pressure drop (energy consumption). With the purpose of that, the paperpresents the “Q/N Index” to evaluate the optimizing scheme and considers the ability of heattransferring and pressure drop comprehensively, the following conclusions are drawn that thescheme is A2B1C2,that is1.5mm pitch,0.25mm thickness and1.4mm height. The promotion of the fluid’s flow rate inside and outside the tube can improve both the heat transferringability of fins and increase the pressure drop, especially the flow rate outside; when the flowrate inside increases, pressure drop changes little; considering the heat transferringperformances comprehensively, the flow rate inside can obtain the maximum value and thevalue outside is5m/s. In order to verify the accuracy of the simulation results, the authorselected four groups of specifications for the copper tube, and use special thermal test benchfor single pipe heat transfer test. At last the paper compared the experimental value withsimulation value, and analyzes the error between the two.