What characteristic defines zeotropes in the context of refrigerants?

What characteristic defines zeotropes in the context of refrigerants?

• A. They are pure substances.
• B. They evaporate at a single temperature.
• C. They separate when changing state.
• D. They require no pressure to operate.

Answer: (C)

Zeotropes are specific mixtures of refrigerants that do not boil at a single temperature. Instead, they have a range of temperatures at which they change states from liquid to vapor or vice versa. This characteristic leads to them separating during the phase change, which means that the composition of the vapor and the liquid can differ as they transition. This separation occurs because zeotropic mixtures contain components with different boiling points. As the mixture heats up or cools down, the components evaporate or condense at different rates. Consequently, the vapor that is produced will contain a different composition than the liquid remaining, leading to a separation of the mixture. Understanding the behavior of zeotropic blends is crucial for HVAC applications, as it influences how these refrigerants perform in cooling systems. This behavior contrasts with pure substances, which boil at a single temperature, and azeotropes, which retain a constant composition throughout the phase change. Since zeotropes do not require any pressure to operate, this attribute is not a defining characteristic for them.

Zeotropes are specific mixtures of refrigerants that do not boil at a single temperature. Instead, they have a range of temperatures at which they change states from liquid to vapor or vice versa. This characteristic leads to them separating during the phase change, which means that the composition of the vapor and the liquid can differ as they transition.

This separation occurs because zeotropic mixtures contain components with different boiling points. As the mixture heats up or cools down, the components evaporate or condense at different rates. Consequently, the vapor that is produced will contain a different composition than the liquid remaining, leading to a separation of the mixture.

Understanding the behavior of zeotropic blends is crucial for HVAC applications, as it influences how these refrigerants perform in cooling systems. This behavior contrasts with pure substances, which boil at a single temperature, and azeotropes, which retain a constant composition throughout the phase change. Since zeotropes do not require any pressure to operate, this attribute is not a defining characteristic for them.