Which refrigerant type has the largest temperature glide?

• A. R-12
• B. Zeotropic Refrigerants
• C. R-22
• D. Hydrofluorocarbon Refrigerants

Answer: (B)

Temperature glide happens when a refrigerant boils and the vapor composition changes during the phase change. Zeotropic refrigerants are blends whose components have different boiling points, so as evaporation proceeds the liquid vaporizes more of one component first, changing the vapor composition and causing the boiling temperature to shift over a range. That creates a noticeable glide in temperature while the liquid boils or the vapor condenses.

Pure refrigerants, like R-12 and R-22, boil at essentially a single temperature at a given pressure, so they exhibit almost no glide. Hydrofluorocarbon refrigerants cover a broad category, including both pure substances and blends, but the largest glide among the options is associated with zeotropic blends, because their mixed components inherently produce a range of boiling temperatures during phase change.