On an R-22 system, what is your subcooling if you have a liquid line pressure of 250 psig and a line temperature of 100°?

To determine the subcooling in an R-22 system, it’s essential to understand the relationship between the pressure, temperature, and the refrigerant's properties. Subcooling is the difference between the temperature of the refrigerant in the liquid line and the saturation temperature corresponding to that pressure.

For R-22 at a pressure of 250 psig, first, we need to convert the pressure to a saturation temperature using refrigerant property tables or pressure-temperature charts. At 250 psig, the saturation temperature of R-22 is approximately 117°F.

Next, compare this saturation temperature to the actual temperature of the refrigerant in the liquid line, which is given as 100°F.

Subcooling is calculated as follows:

Subcooling = Saturation Temperature - Actual Line Temperature

Substituting the known values:

Subcooling = 117°F - 100°F

Subcooling = 17°F

This calculation shows that the correct amount of subcooling in the system is 17°F, meaning the refrigerant has been cooled down below its saturation point, making it less likely to vaporize before reaching the expansion device. Proper subcooling ensures efficiency in the system’s performance and optimizes the cooling