Environmental Systems Flashcards
How is the heat removed from an aircraft cabin with a vapor-cycle air conditioning system?
The cabin heat is absorbed by the refrigerant in the evaporator, then carried outside the aircraft where it is given up to the outside air in the condenser.
What produces the cool air in a vapor-cycle air conditioning system?
Warm cabin air is blown across the evaporator, where its heat is transferred into the refrigerant. The air that leaves the evaporator is cool.
What is used as the refrigerant in a vapor-cycle air conditioning system?
A Freon-type liquid refrigerant known as Refrigerant 12, or the more environmentally friendly R-134a.
What is the state of the refrigerant as it leaves the compressor?
It is a high-pressure gas.
What is the state of refrigerant as it leaves the condenser?
It is a high pressure liquid.
What is the state of the refrigerant as it leaves the thermostatic expansion valve?
It is a low-pressure liquid.
What is the state of the refrigerant as it leaves the evaporator?
It is a low-pressure vapor.
How is the compressor lubricated?
Refrigeration oil is mixed with the refrigerant and it circulates through the compressor and the entire system.
What is the function of the thermostatic expansion valve?
It meters just enough liquid refrigerant into the evaporator that all of it will be evaporated by the time it leaves the evaporator coils.
