Lee相变传质方程中传质系数取值的分析

Analysis on the value of coefficient of mass transfer with phase change in Lee′s equation

摘要:

针对Lee相变传质方程中传质系数主要依靠经验取值的问题,本文尝试提出一种确定传质系数的方法,给出了评价传质系数合理性的2个指标——潜热份额(潜热换热量占总换热量的份额)和饱和温差(流体温度与饱和温度的差值),建立了稳态分析模型,通过理论推导,得出了潜热份额和饱和温差的理论表达式,据此分析了传质系数对模拟结果的影响,已有特定条件下的理论解验证了本文分析结果的正确性．分析结果表明传质系数越大,计算精度越高．基于分析结果解释了不同文献对该系数取值差异很大的原因,并给出了传质系数的通用取值方法,最后推荐了常见工况模拟中传质系数的合理取值范围．

Abstract:

To solve the problem that the mass transfer coefficient in Lee's equation need to be obtained depending on the experience, a method was proposed, and two indexes evaluating the rationality of the mass transfer coefficient-latent heat share (the share of latent heat flux in total heat flux) and saturation temperature difference (difference between fluid temperature and saturation temperature) were presented. A steady state model was established to analyze this problem and the expression of latent heat share and saturation temperature difference were obtained by the theoretical guidance. By the expression, the effect of mass transfer coefficient on the simulation was analyzed. The analysis result was validated by the existing theoretical result in particular cases. The results show that the calculation accuracy increases with the increase of the coefficient. Based on these results, the reason for large difference of the coefficient value in different literatures was explained, the method of how to get the coefficient value was presented, and the value range of easy-to-use was suggested.