An Ammonia refrigerant line at 181 PSIG and 77ºF indicates the refrigerant is:

In the context of refrigeration and understanding the properties of ammonia as a refrigerant, the correct classification of the refrigerant line at 181 PSIG and 77ºF is that it is sub-cooled.

To determine whether a refrigerant is sub-cooled, saturated, or in a superheated state, one can refer to the ammonia saturation temperature at the corresponding pressure. For ammonia at 181 PSIG, the saturation temperature is significantly lower than 77ºF. Therefore, at 181 PSIG, ammonia would actually be in a superheated state if the temperature exceeded that saturation temperature. However, because the temperature indicated is 77ºF, which is above the saturation temperature but does not exceed the superheat range, it marks the refrigerant as sub-cooled.

Sub-cooling refers to the state of the refrigerant when it is cooled below its condensation temperature at a given pressure. When the refrigerant is sub-cooled, it means that it has dissipated more heat beyond its saturation point and is in a liquid state, ready to absorb heat in the evaporator.

Understanding the pressure-temperature relationship for ammonia helps in recognizing how refrigerants behave under various operational conditions, which is essential for effective and efficient system design and