If refrigerant R-134a vapor enters the condenser at 124 PSIG and 100°F, what pressure will it be approximately at upon leaving at 80°F?

To determine the pressure of refrigerant R-134a upon leaving the condenser, it’s important to understand the relationship between pressure and temperature in a refrigeration cycle, specifically in the condensation phase. When R-134a is in the condenser, it starts as a vapor and loses heat, transforming into liquid as it condenses.

The pressure of refrigerant R-134a is directly related to its saturation temperature. At 100°F, R-134a is at a pressure of 124 PSIG, indicating that it is well above the saturation point for a vapor. When the temperature drops to 80°F, the refrigerant is still in the condenser, but it has released heat and is closer to the saturation point where it begins to condense.

At 80°F, R-134a's saturation pressure is about 87 PSIG. Since the refrigerant is condensing, its pressure will stabilize around this saturation pressure at the equilibrium temperature of 80°F. Therefore, upon leaving the condenser, the refrigerant will approximately be at the saturation pressure corresponding to the exit temperature, which aligns with the provided answer of 87 PSIG.

This understanding highlights how, in a condenser, as the refrigerant cools, it will