Which refrigerant type is characterized by having a mixture with similar boiling points?

The correct choice is based on the fundamental properties of azeotropic refrigerants. Azeotropes are mixtures of two or more substances that exhibit a constant boiling point and composition throughout the phase transition, meaning that when the mixture is heated, it evaporates at that specific boiling point without changing its composition. This characteristic makes azeotropic refrigerants unique because they behave like a single component, simplifying the refrigeration process since their boiling and condensation occurs at a consistent temperature.

In contrast, zeotropic mixtures do not have this behavior; they consist of components with varying boiling points. When zeotropic mixtures are heated, the more volatile components tend to vaporize first, causing the composition of the liquid phase to change over time. This results in temperature glide, where the boiling and condensation temperatures vary during the phase transition.

Understanding the distinction between azeotropes and zeotropes is crucial for efficient system design and operation in refrigeration and air conditioning, as azeotropes provide more predictable thermal properties under standard operating conditions.