The Study Of Numerical Simulations And Digital Prototype On Spiral-wound Heat Exchangers

Spiral-wound heat exchanger is a kind of heat exchanger with the features of compact structure,high heat transfer coefficient and low temperature difference,which has great potential.In China,the spiral-wound heat exchanger has been introduced,but design and manufacturing technology is still lagging behind.There is a little research on flow and heat transfer characteristics of fluid in spiral-wound heat exchangers,and the effect of structure on performance as well.In this paper,numerical simulations were conducted to investigate flow and heat transfer performance in spiral-wound heat exchangers,including the effect of structure size and different helically coiled tubes.Digital prototype technology was studied for spiral-wound heat exchangers.And the basic function of digital prototype on spiral-wound heat exchangers was realized by ICEM CFD?Fluent?MATLAB software secondary development.The major works and conclusions are as follows:(1)The model of the spiral-wound heat exchanger was simplified.The numerical simulation method in this paper was verified to be reliable.The flow and heat transfer in shell side of the spiral-wound heat exchanger were analyzed.The results show that radial flow is an important characteristic of fluid flow in shell side,there is fluid exchange between inside and outside of tube layers which improves heat transfer performance.(2)Effects of 4 structural parameters including tube layers,tube diameter,space bar thickness and longitudinal distance on flow and heat transfer characteristics in shell side were analyzed.Results show that:Nusselt number remain unchanged,friction coefficient f increase,performance evaluation criteria ? remain unchanged with increase of tube layers.Nusselt number decrease,friction coefficient f increase,performance evaluation criteria ? decrease with increase of tube diameter.Nusselt number increase,friction coefficient f decrease,performance evaluation criteria ? increase with increase of space bar thickness.Nusselt number,friction coefficient f and performance evaluation criteria ? increase first and then decrease slightly with increase of longitudinal distance.(3)Numerical simulations were conducted to investigate flow and heat transfer performance in helically coiled tubes with circular,ellipse,rectangle cross-section using numerical simulations.The velocity field,the temperature field and the fields synergy in helically coiled tubes with different cross-sections were analyzed.The results show that secondary flow in different-cross-section tube effects the temperature field and the fields synergy and then improves heat transfer performance.The heat transfer of helically tube with circular cross-section is the best.For the tube with ellipse and rectangle cross-section,the one with bigger size ratio of radial direction of helix to axial direction has better performance.With the increase of Reynolds number,the influence of the fields synergy on heat transfer declines while the influence of turbulent flow raises.(4)Modeling,simulation and reconstruction technology of digital prototype of spiral-wound heat exchangers was investigated.Parametric modeling was realized by secondary development in ICEM CFD.CFD numerical simulations was realized by secondary development in Fluent.Graphical User Interface was realized by MATLAB.The basic function of digital prototype on spiral-wound heat exchangers was realized.