Trane TRG-TRC003-EN User Manual

Page of 53
TRG-TRC003-EN
19
period three
Refrigeration Cycle
notes
The liquid refrigerant absorbed heat from the air while it was inside the 
evaporator, and was transformed into a vapor in the process of doing useful 
cooling. Earlier in this clinic, we demonstrated that if the heat is then removed 
from this vapor, it will transform (condense) back to its original liquid phase.
Heat flows from a higher temperature substance to a lower temperature 
substance. In order to remove heat from the refrigerant vapor, it must transfer 
this heat to a substance that is at a lower temperature. Assume that the 
refrigerant evaporated at -41.4°F [-40.8°C]. To condense back into liquid, the 
refrigerant vapor must transfer heat to a substance that has a temperature less 
than -41.4°F [-40.8°C]. If a substance were readily available at this cooler 
temperature, however, the refrigerant would not be required in the first place. 
The cooler substance could accomplish the cooling by itself.
How can heat be removed from this cool refrigerant vapor, to condense it, using 
a readily-available substance that is already too warm for use as the cooling 
medium? What if we could change the temperature at which the refrigerant 
vapor condenses back into liquid?
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