Which condition increases the fractionation risk for zeotropic blends?

Which condition increases the fractionation risk for zeotropic blends?

• A. Leaks or partial condensation
• B. Very high ambient temperature
• C. Complete sealing of the system
• D. Using azeotropic blends

Answer: (A)

In zeotropic blends, the components have different boiling points, so as the mixture boils or condenses, the vapor and liquid phases become enriched in different components. This tendency for the composition to shift during phase change is called fractionation. Leaks or partial condensation specifically increase this risk because they selectively remove portions of the vapor or liquid that are richer in the more volatile component. When gas leaks out, the escaping vapor carries away more of the light component, leaving the remaining mix enriched in the heavier component. Partial condensation can remove certain components from the vapor before it fully exchanges with the liquid, again altering the overall composition over time. Those processes actively drive the blend away from a uniform composition, amplifying fractionation. High ambient temperature doesn’t by itself cause ongoing fractionation; it may change pressures and boil points but doesn’t inherently separate components. Complete sealing reduces fractionation because there’s no loss of vapor to the environment. Using azeotropic blends avoids fractionation altogether because their composition remains constant during phase change.

In zeotropic blends, the components have different boiling points, so as the mixture boils or condenses, the vapor and liquid phases become enriched in different components. This tendency for the composition to shift during phase change is called fractionation. Leaks or partial condensation specifically increase this risk because they selectively remove portions of the vapor or liquid that are richer in the more volatile component. When gas leaks out, the escaping vapor carries away more of the light component, leaving the remaining mix enriched in the heavier component. Partial condensation can remove certain components from the vapor before it fully exchanges with the liquid, again altering the overall composition over time. Those processes actively drive the blend away from a uniform composition, amplifying fractionation.

High ambient temperature doesn’t by itself cause ongoing fractionation; it may change pressures and boil points but doesn’t inherently separate components. Complete sealing reduces fractionation because there’s no loss of vapor to the environment. Using azeotropic blends avoids fractionation altogether because their composition remains constant during phase change.