Given a suction header pressure of 38 PSIG and a suction header temperature of 50°F, how much superheat is found at the outlet of the evaporator?

To determine the amount of superheat at the outlet of the evaporator, it is essential to understand the relationship between pressure, temperature, and the properties of refrigerants in the context of a refrigeration cycle.

Given a suction header pressure of 38 PSIG, we first convert this pressure to absolute pressure by adding the atmospheric pressure (approximately 14.7 PSIA). Therefore, the absolute pressure becomes 38 + 14.7 = 52.7 PSIA.

Next, we can consult the refrigerant properties table for the specific refrigerant being used (often R-22 or R-134A in these examples) to find the saturation temperature corresponding to 52.7 PSIA. At this pressure, the saturation temperature is typically around 26°F for common refrigerants.

The suction header temperature is given at 50°F. To find the superheat, we calculate the difference between this actual outlet temperature (50°F) and the saturation temperature (26°F).

Superheat is the amount of heat added to the refrigerant vapor above its saturation temperature, so we can find it as follows:

Superheat = Outlet Temperature - Saturation Temperature

Superheat = 50°F - 26°F = 24°F

The closest