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℃.