Final answer:
The evaporation temperature of R-134a at 0 psig is approximately -26.3°C (-15.3°F), which is its boiling point at atmospheric pressure, and the same as the gauge pressure of 0 psig that equals atmospheric pressure.
Step-by-step explanation:
The evaporation temperature of R-134a at 0 psig refers to the point where the refrigerant transitions from a liquid to a gas state at atmospheric pressure, which is also known as the boiling point. At sea level (1 atm or 14.7 psia), the boiling point of R-134a is approximately -26.3°C (-15.3°F). However, when we refer to 0 psig, it typically means gauge pressure, which does not account for atmospheric pressure.
Since gauge pressure is relative to atmospheric pressure, 0 psig is essentially atmospheric pressure, making the evaporation temperature at 0 psig the same as the boiling point at atmospheric pressure. Therefore, the evaporation temperature of R-134a at 0 psig is approximately -26.3°C (-15.3°F). It is critical to note this is the case at sea level, and the evaporation temperature will be different at altitudes higher or lower than sea level due to changes in atmospheric pressure.