An Ammonia refrigerant line at 10 PSIG and -8ºF shows the refrigerant is:

The correct answer indicates that the refrigerant is in a saturated state (SAT), which means it is at a specific pressure and temperature where it can coexist as both a liquid and a vapor. In the context of ammonia, the provided conditions of 10 PSIG and -8ºF can be analyzed using a pressure-temperature chart specific to ammonia.

At 10 PSIG, which is equivalent to about 24.7°F, the temperature of -8ºF is below the saturation temperature of ammonia. However, in refrigeration systems, such conditions can indicate a state that involves both saturated liquid and vapor, particularly when discussing the points of operation near the evaporator or how the system cycles.

In this scenario, since the temperature is below the saturation point, it typically wouldn't simply represent superheat or sub-cooling scenarios. Superheating occurs when the refrigerant vapor is heated beyond its saturation temperature without an increase in pressure, while sub-cooling refers to liquid refrigerant being cooled below its saturation temperature at the same pressure. Given the specific temperature and pressure, it aligns with the notion of being on the saturation curve, thus supporting the classification of the refrigerant state as saturated.

The references to trans-critical conditions usually apply to systems that function