多通道烘缸水平通道内蒸汽凝结换热的研究

Heat Transfer of Steam Condensation in the Horizontal Channel of Multi-channel Dryer

关键词:  纸张干燥  多通道烘缸  水平矩形通道  凝结换热关联式  凝结换热系数

Key Words:paper drying  multi-channel cylinder dryer  horizontal rectangular channel  condensation correlation  condensation heat transfer coefficient

摘要:多通道烘缸是解决纸张干燥能耗较高问题的优化方案之一，蒸汽凝结换热是其通道内热量传递的重要途径。本研究对不同凝结条件下多通道烘缸水平矩形通道内的蒸汽凝结换热系数的变化进行了分析。结果表明，蒸汽凝结换热系数随着蒸汽质量通量和冷却水雷诺数的增加而增加，但凝结水换热系数会随冷却水雷诺数的增加而发生波动；通过增加蒸汽质量通量可以实现水平通道内更好的换热性能，当蒸汽质量通量设为24 kg/(m²·s)时可以避免过度的两相流压力降。采用现有凝结换热关联式对凝结换热系数进行计算，并与实验值进行对比，发现Shah(1979)关联式对多通道烘缸水平通道内的蒸汽凝结换热系数具有较好的预测能力。

Abstract:In this paper， the change of condensation heat transfer coefficients in the horizontal rectangular channel of a multi-channel cylinder dryer under different condensation conditions was analysed. The results showed that the condensation heat transfer coefficient increased with the increase of steam mass flux and the Reynolds number of cooling water. However， there was a fluctuation of the condensation heat transfer coefficient with the increase of the Reynolds number of cooling water. A better heat transfer performance could be achieved by increasing the steam mass flux， meanwhile， excessive pressure drop of two-phase flow could be avoided by setting the steam mass flux of 24 kg/（m²∙s）. It was found that the Shah (1979) correlation had a better predictability for the steam condensation heat transfer coefficient in the horizontal channel of the multi-channel dryer through comparing the experimental value and the calculated value of the condensation heat transfer coefficient calculated by the existing condensation heat transfer correlation.