What is the term used to describe the temperature difference between the bubble point and the dew point of a zeotropic refrigerant?

The term that describes the temperature difference between the bubble point and the dew point of a zeotropic refrigerant is known as "glide." In refrigeration, zeotropic refrigerants do not evaporate and condense at a single temperature, unlike azeotropic mixtures. Instead, they exhibit a temperature range during phase changes. The bubble point is the temperature at which the refrigerant begins to evaporate (turns from liquid to gas), while the dew point is the temperature at which the refrigerant begins to condense (turns from gas to liquid). The difference between these two points is referred to as "glide," highlighting the unique behavior of zeotropic mixtures in refrigeration applications.

The other terms in the options refer to different concepts. Saturation refers to the state of a substance when it is in a balance between liquid and vapor phases at a given pressure. Pressure difference relates to the variation in pressure necessary for various processes in HVAC systems, while phase change pertains to the transition between different states of matter, such as from liquid to gas. Glide specifically encapsulates the varying temps during the phase transition of zeotropic mixtures, making it the right choice in this context.