environmental systems Flashcards
how is the heat removed from an aircraft cabin with 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 the 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 low pressure vapor
how is the compressor lubricated
refrigerant 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
how is refrigerant put into the system
it is put into the system through service valves on the low side of the system using a manifold gauge set
how should the components in the low side of a properly operating vapor cycle cooling system feel
the should feel cool
how is a vapor cycle cooling system checked for refrigerant leaks
hold the probe of an electronic leak detector below any suspect fitting or component. if there is a leak, the tone of the sound produced by the detector will change
what safety equipment should be worn when charging a vapor cycle cooling system
air cycle systems and vapor cycle systems
what is the function of the cabin outflow valve on a pressurized aircraft
the cabin outflow valve, which is controlled by the pressure controller maintains the correct amount of pressure inside the cabin
what is the function of the cabin pressure safety valve on a pressurized aircraft
the cabin pressure safety valve prevents cabin pressure from exceeding the maximum allowable differential pressure
