Another similar scenario would be a refrigeration system containing air, as in Table 3. Air is a noncondensable and will get trapped in the top of the condenser. This will cause high head pressures and high condensing temperatures because of reduced condenser volume to desuperheat, condense, and subcool. Thus, the liquid at the condenser’s bottom will be hotter than normal and will lose heat faster to the ambient. This will result in an increase in condenser subcooling.
Table 3 shows 40? of condenser subcooling, but these amounts will vary depending on the amount of air in the system.
Again, in this example, high condenser subcooling is not caused from an “amount” of liquid being backed up in the condenser, but from the liquid in the condenser’s bottom simply losing heat faster.