垫条对缠绕管换热器壳侧性能的影响研究
Effects of Space Bars on the Shell？？Side Performance of Spiral？？Wound Heat Exchanger

目前针对缠绕管换热器的数值模拟研究中,大多为了简化模型而省略了管层间的垫条,造成模拟结果偏离实际情况。通过CFD数值模拟,着重研究了缠绕管换热器中垫条的存在及不同的排布方式和数量对换热器壳侧的流动、传热性能的影响。计算结果表明,垫条的存在不仅影响流体轴向流速,并且在径向截面上更易形成涡旋而加强流体扰动。在相同进口工况下,相比无垫条模型,垫条对齐排布时Nu下降了1.6％～2.5％,换热器单位长度压降ΔPl增加了14.5％～17.0％,强化传热性能指标FP减小了5.7％～5.9％;错开排布时Nu上升了17.0％～18.1％,ΔPl增加了38？？4％～39.9％,FP增加了13.7％～15.4％。两种垫条排布方式中错开排布能够在更大程度上强化壳侧的湍流,从而强化传热。当垫条数量多于12,依次为13、14、15时,对换热器壳侧的性能影响不大。所做研究为缠绕管换热器的数值模拟提供了新的思路,也为缠绕管换热器的性能优化提供了理论参考。
So far in the simulation research of spiral？？wound heat exchanger the space bars are rarely considered, the deviation between simulation results and actual situation is thus enlarged. This paper mainly studies the effects of the number and arrangement of space bars on the shell side’s thermal and hydraulic performance with numerical simulation method. Numerical results showed that the space bars affect the axial flow rate of shell side and cause more vortexes in radial sections. Compared with the calculation results of the models without space bars under the same inlet condition the Nusselt number Nu of lined up？？space bar models was decreased by 1.6％~2.5％; the pressure drop per heat exchanger length ΔPl was increased by 14.5％~17.0％; the performance evaluation criteria FP was decreased by 5.7％~5.~9％; the Nu of staggered？？space bar models was increased by 17.0％~18.1％; ΔPl was increased by 38.4％~39.9％ and FP was increased by 13.7％~15？？4％. Moreover, the staggered arrangement of space bars can further enhance the turbulence of shell side, compared with the lined up arrangement the Nu of staggered arrangement was increased and ΔPl was increased accordingly in the same working conditions. When the number of space bars was more than 12 (13, 14 and 15), the number of space bars had little effect on the shell side performance. This paper provides a new approach for spiral？？wound heat exchanger simulation and offers a theoretical reference for the performance optimization