What defines the critical point of a refrigerant?

The critical point of a refrigerant is defined as the highest temperature and pressure at which a liquid can exist. At this point, the properties of the liquid and vapor phases become indistinguishable, meaning that the refrigerant cannot be converted to a liquid regardless of how pressure is applied. This characteristic is crucial in refrigeration systems since it determines the operational limits of the refrigerant under various conditions.

Understanding the critical point is essential for system design, particularly when considering the thermal properties and behaviors of refrigerants. At temperatures and pressures beyond the critical point, the refrigerant exists in a supercritical state, where it can act as both a gas and a liquid. Recognizing this helps in selecting appropriate refrigerants for different applications and ensuring efficient system performance.