What is the term for the volume occupied by a refrigerant under specified conditions of pressure and temperature?

The term that describes the volume occupied by a refrigerant under specified conditions of pressure and temperature is specific volume. Specific volume is defined as the volume per unit mass of a substance, allowing for the comparison of how much space a specific mass of refrigerant will occupy at different pressures and temperatures. This property is crucial in thermodynamics and refrigeration cycles, as it helps engineers and technicians understand how refrigerants behave under various conditions.

In contrast, density is the mass per unit volume and while it is related to specific volume, it does not account for the effects of pressure and temperature as specifically as specific volume does. Critical volume refers to a specific state that occurs at the critical point, where the properties of the gas and liquid phases become indistinguishable, and is not relevant to the general conditions outlined in the question. Saturated volume relates to the volume of refrigerant at its boiling or condensing point but similarly does not encompass the broader range of conditions in question. Thus, specific volume is the appropriate term here, capturing the relationship of refrigerant volume under defined states of pressure and temperature.