Numerical Simulation Of Performance For Fully Slotted Stsggered Finned Tube Heat Exchanger

Traditional air conditioning system has serious energy loss and potential health risks.Independent temperature and humidity control air conditioning system has the advantages of comfort,health and energy saving.Therefore,it is of great significance to conduct a lot of research and promote the application of independent temperature and humidity control air conditioning system.As the sensible end of the air conditioning system with independent control of temperature and humidity,the end of the dry fan coil has many advantages over the end of the conventional air conditioning system,but there are also problems such as insufficient heat transfer,limited use occasions and immature technology,etc.It is particularly important to improve the heat transfer performance of the end heat exchanger and expand its application range.In this paper,two new types of finned tube heat exchanger structures,namely,flat-row fin and staggered fin in the form of full-slit were proposed.The heat transfer and flow performance of the air side were studied by using the hydrodynamics software CFD.The main research contents are as follows:(1)The local numerical models of flat and staggered fins were established,and the computational domain is divided by structured grid.Under the same solution condition,the central curve temperature when the number of grids is about 0.6 million and 1.8 million is taken as the object of study,and it is found that the number of grids about 0.6 million meets the requirement of calculation accuracy,and the grid quality is still relatively high.(2)The heat transfer and drag characteristics of flat and staggered fins at different inlet air velocities were numerically calculated,gives the heat exchange amount Q,import and export pressure drop?p,heat exchange factor j and resistance coefficient f along with the change of inlet air velocity curve,it is concluded that the different inlet air flow rate of two types of finned heat transfer and flow resistance are studied.(3)Air flow between the fin surface and center fin surface in the plane of the 0.5mm(y=1.63 mm)temperature and velocity distribution are analyzed,and found that the isotherm of the center and the area near the surface of the staggered fin is denser than that of the flat fin,velocity gradient bigger around the wall.In addition,the area of the wake area of the pipe wall is greatly reduced due to the good turbulence effect of the staggered fins,so that the heat transfer effect of the staggered fins is better,which has the value of popularization and application.(4)By comparing the fin efficiency?_f and the comprehensive heat transfer performance index j/f of the flat and staggered fins,it is found that the?_f of the staggered fins was lower than that of the flat fins,and the structure optimization was needed to improve the economy of the fins.The results show that when the air supply velocity is 2m/s(air volume:756m3/h),the heat transfer performance of the staggered fin is the best,and the wind speed is more favorable for the heat transfer effect of the staggered fin.In this paper,the heat transfer and resistance characteristics of flat fin and staggered fin under different inlet air velocity are simulated and analyzed,and the influence law of air velocity on the heat transfer and resistance characteristics of finned tube is obtained,and the best finned tube heat exchanger with the best comprehensive heat transfer performance and the best air supply velocity are determined,which provided a reference for the related research on strengthening heat transfer capacity of this kind of heat exchanger.