水平管束冷凝换热设计计算问题讨论

Discussion of Calculation and Design for Heat Transfer under Condensation with Horizontal Tube Bundles

针对大型水平管束冷凝换热设计计算,对水平管束膜状冷凝换热系数典型公式进行了对比分析;结合管束结构及冷凝液膜流动行为,阐明了相关公式的适用条件、计算结果差异及原因。然后通过工程实例计算对比和壳程蒸汽流动模拟进一步表明,现有相关公式因未能充分考虑冷凝加热器中蒸汽流动的多方向性及其对冷凝液膜的扰动,其换热系数计算值明显低于实际;并针对大型水平管束冷凝换热工程计算模型的完善,对进一步的研究工作提出了建议。

For heat transfer design under condensation condition for large horizontal tube bundles,several typical equations used in calculating film coefficients were compared and analyzed.Combined with bundle structure and flow of condensed liquid film,the applicable conditions,differences in calculation results and causes for the creation of these differences were explained in this article.With engineering examples and simulation of steam flow in shell side,it was further shown that the heat transfer coefficient resulted from currently applied equation is apparently lower than practical value because in this equation the multi directions of steam flowing in condensation heater and disturbing effect to condensed liquid film are not taken into account.Then,with respect to the improvement of engineering heat transfer calculation model for large horizontal tube bundle condenser,the proposal for further research was presented.