What characteristic is unique to zeotropic blends?

Zeotropic blends are mixtures of refrigerants that have different boiling points. One of the defining traits of these blends is temperature glide, which means that as the refrigerant evaporates, it changes temperature over a range rather than at a single, fixed temperature. This occurs because the components of the zeotropic blend evaporate at different rates, leading to a gradual temperature change as the mixture transitions from liquid to vapor.

This characteristic can be important in cooling applications, as it can affect the efficiency and performance of an air conditioning system. The presence of temperature glide requires careful consideration in system design, particularly in the configuration of heat exchangers.

In contrast, constant boiling point is a trait of azeotropic mixtures, which maintain a consistent boiling point as they evaporate. While high toxicity and no pressure change might be relevant in discussions of refrigerants, they do not define zeotropic blends specifically. The unique feature of temperature glide is what sets zeotropic mixtures apart in the context of refrigeration cycles.