Which refrigerant is known for being a zeotropic mixture?

R404A is classified as a zeotropic mixture, which means it is composed of two or more refrigerants that do not evaporate or condense at the same temperature and pressure. Zeotropic blends have a temperature glide during phase changes, which can impact the performance of refrigeration systems. In contrast, R410A is an azeotropic mixture, where the components behave as a single substance, and R134A and R12 are single-component refrigerants. Understanding these characteristics of refrigerants is crucial for selecting appropriate fluids for specific applications and ensuring efficiency during operation.