Study On The Heat Transfer Characteristics Of Spiral-wound Heat Exchanger

As an efficient heat exchanger,spiral-wound heat exchanger has the advantages of compact structure,high heat transfer efficiency,high pressure resistance and multistream heat transfer.The research on heat transfer performance of spiral-wound heat exchanger has great guiding significance for the optimization and improvement of the structure.In this paper,the effects of different turbulence models on the flow and heat transfer of single-tube spiral-wound heat exchanger,the arrangement of different winding-tubes and the filling ratio of fluid in different tube paths on the flow and heat transfer of the spiral-wound heat exchanger are studied by heat transfer and flow coupled method systematically.The main contents and results are summarized as follows:CFD software was used to simulate the single-tube spiral-wound heat exchanger,and the effects of different turbulence models in Fluent software on the calculation results were investigated.Results showed that the error between the results of the Realizable k-? turbulence model and the experiment was about 4.06%,while that of the RNG turbulence k-? model was about 13.49%.Accordingly,Realizable k-? turbulence model was more suitable for the calculation of single-tube spiral-wound heat exchanger.The flow and heat transfer performance of heat exchanger with different arrangement of spiral tubes were simulated,the velocity field,pressure field and temperature field under different working conditions were analyzed,and the heat transfer performance of heat exchangers was analyzed by PEC criterion.Results showed that under the same conditions,the velocity and temperature distributions on the shell side of crosswise arrangement heat exchangers were more uniform than those of coarrangement heat exchangers,the axial temperature gradient of crosswise arrangement heat exchanger was smaller than that of co-arrangement heat exchanger,the maximum difference percentage was about 8.12%.The shell-side pressure drop of the coarrangement heat exchanger was 13.73%~18.04% lower than that of the crosswise arrangement heat exchanger.The PEC value of the co-arrangement heat exchanger was 11.77%~30.62% lower than that of the crosswise arrangement heat exchanger.The concept of ‘loading rate of tube fluid' was put forward.The flow and heat transfer performances of spiral-wound heat exchanger with 25.52%,27.67% and 29.63% fluid filling ratios were simulated.Results showed that with the increase of the loading rate of tube fluid,the heat transfer performance of heat exchangers decreased continuously,and the maximum difference of PEC values among the three heat exchangers was about 15.91%.Even so,the heat transfer area of heat exchanger increased gradually with the increase of the loading rate of tube fluid,and the maximum heat transfer area can be increased about 16.10%,which can provide higher heat quantity.