Abstract: Zeotropic mixtures are considered to be popular alternatives to chlorofluorocarbons and hydrochlorofluorocarbons in refrigeration systems.It has been discovered that composition shift of multicomponent mixtures will have negative effect on system performance.In order to reveal the influence of gravity on composition shift,by varying mass fraction,temperature and standing time and using refrigerants Z1,Z2 and Z3 (R290/R600,25%/75%,50%/50% and 75%/25%,by mass fraction)as working fluids,an experimental study of composition shift was carried out in a vertical copper tube with internal diameter of 10 mm and length of 2 m.A chromatographic analysis test bench was used to make an analysis on the composition shift and bring forward research suggestions.The results show that composition shift is weakly dependent on the mass fractions of mixtures.At 28.0℃,prolonging the standing time from 3 h to 24 h,decline rate of propane in the liquid phase varies from "large—small—large" to "decrease gradually",and composition shift of propane increases by 70.13%.In 3 h of standing time,composition shift of propane decreases 61.25% as the temperature increases from 28.0℃ to 40.0℃.

Key words: zeotropic mixture, gravity, composition shift, vertical tube

摘要： 为探究重力对非共沸混合工质组分迁移的影响,在竖直管式色谱分析实验台上,以R290/R600(Z1、Z2、Z3,质量比分别为25%/75%、50%/50%、75%/25%)为工质,通过改变配比、温度和静置时间等变量进行了不同工况下的实验研究,对组分变化的规律做出了理论分析并提出了进一步的研究建议。实验发现:对于工质Z1、Z2、Z3,组分迁移度受混合物配比的影响很小;温度28.0℃的条件下,将静置的时间由3 h延长至24 h后,液相中丙烷递减率由"大—小—大"的趋势向"逐渐减小"变化,同时丙烷组分迁移度增大了70.13%;静置3 h的条件下,将温度由28.0℃升高至40.0℃后,丙烷的组分迁移度减小了61.25%。

关键词: 非共沸混合工质, 重力, 组分迁移, 竖直管