Research On The Condensation Heat Transfer In The Shell Side Of Spiral-wound Heat Exchanger With Different Tube Diameters

Because of the complication of shell pass construction,it was more research on uniphase condition of spiral coil heat exchanger at present,most of the experiments are research single outside tube,it’s not comply with the reality operating mode.In the engineering application,most optimized structures are new typed heat tube,which are difficult to manufacture.Therefore,new construction ofspiral-wound heat exchanger with different tube diameters be research objective in this article.The research content in this article as below :(1)Development new typed spiral-wound heat exchanger with different tube diameters,the mainly construction feature is the two types of core tube outside winding pipe: large diameter winding tube and small diameter winding tube,large diameter winding tube and small winding tube cross and wound in the same layer,large diameter winding tube to supporting with each other between the layers.Between small winding tube and large winding tube have a bit more space.The advantage of new construction’s arrangement is mainly to using different diameter winding tube to alternate winding in the same layer,enlarge the radial spacing between the layers of heat exchange tubus,solves the problem of arrangement close together in the same tube layer,strengthen the effective of disturbed flow in shell side:For the structure of tube side,adopt part of small winding tube,the flow velocity in the tube can be greatly increased.(2)Put the heat exchanger with different tube diameters to simulation comparison,the result shows that the distributed of flow speed in reducer are more average,death of flow area are more small,the distribution of fluid velocity in reducer are more uniform,the flow death zone is smaller,the radial velocity component density is larger,the pressure drop is greatly reduced,comprehensive performance is better than equal diameter tube wound heat exchanger.To using simulation method analyze the influence of flow and heat transfer in shell side between tube diameter ratio and axial pipe center distance of reducer wound heatexchanger.The result shows that in the research range,when a=1.250,Z=3mm,the comprehensive performance is more better.(3)Combined with UDF,simulated analyzed the flow and heat transfer in the shell side condensation condition of spiral-wound heat exchanger with different tube diameters.The result show that with the increase of axial angle of different cross sections in shell side,the development of turbulences becomes more and more uniform,the condensation liquid becomes more and more obvious.Condersation water produced by condersation is mainly deposited in the lower part of heat exchange tube,the turbulence in the middle part of shell side are develops rapidly.The speed of shell side entrance is the important factor which is affecting condensation with the increasing speed of shell side entrance,condensation heat transfer coefficient was raising.(4)Advance process calculation method,construction design and install mode in operating mode of spiral-wound heat exchanger with different tube diameters in single phase and double phase.Through the result of simulated,to get the calculation formula of the convective heat transfer coefficient in the shell side under the operating mode of single phase and double phase.