不同压力下水-乙醇混合蒸汽浓度的计算

二元混合蒸汽的气相浓度与液相浓度和压力有关。通常二元混合蒸汽的浓度可用滴定的实验方法确定,但当压力在负压时,滴定法难于应用。本文使用计算法,利用UNIFAC基团贡献法计算模型,使用VB语言编制了在低压(0～101325)Pa下,乙醇水溶液相平衡计算程序。通过与文献的比较,气相浓度和露点温度的最大的相对误差为9.1%和3%,表明计算方法具有较高的准确性。利用该程序,绘制了3个压力下的相平衡图。

Evaporation of a Thin Binary Liquid Film by Forced Convection into Air and Superheated Steam

This paper deals with a numerical analysis of the evaporation of a thin binary liquid film by forced convection inside a channel constituted by two plates.The first plate is externally insulated and wetted by a thin water ethylene glycol film while the second is dry and isothermal.The first part is concerned with the effects of inlet ambiance conditions and the liquid concentration of ethylene glycol on the distribution of the velocity,temperature,concentrations profiles and the axial variation of the evaporation rate.The second part is focused on the inversion temperature point of the evaporation of binary liquid film.Results show that the inversion temperature phenomenon for the evaporation of binary liquid mixture is observed for high liquid concentration of ethylene glycol.The present results show that in the inlet temperature range considered here,the inversion temperature does not exit for the evaporation of pure ethylene glycol.