Two basic categories of chillers are the _____. - ANSWER Compression cycle and
absorption
The five requirements for comfort are proper temperature, humidity, filtration, _____.
- ANSWER Circulation
The primary function of an expansion device is to _____. - ANSWER All of the
above (produce a reduction in the pressure on the liquid refrigerant, regulate the flow
of refrigerant into the evaporator and lower the boiling point of the refrigerant far
enough below the temperature of the load to get the needed heat transfer rate.
The wet-bulb depression is _____. - ANSWER The difference between the dry-
bulb and wet-bulb temperatures.
The dew-point temperature is the _____. - ANSWER Temperature when the
moisture begins to condense out of the air.
How many Btu are required to change one pound of ice at 20°F to steam at 220°F -
ANSWER 1,304 Btu/h
If an R-12 refrigeration system is operating with a 25.4 psig suction pressure, what is
the evaporator superheat if the evaporator outlet temperature is 34°F - ANSWER 9
On an R-11 or R-123 system, the refrigerant removal process normally starts with
the removal of _____. - ANSWER Liquid refrigerant
The condenser in a refrigeration system _____. - ANSWER All of the above
(desuperheats the vapor from the compressor, condenses the vapor from the
compressor and subcools the liquid refrigerant before it leaves the condenser)
The human body gives off heat by which of the following? - ANSWER All of the
above (convection, radiation and conduction)
If the temperature remains constant and the volume that a gas occupies increases,
the pressure will _____. - ANSWER decrease
Transformers are rated using _____. - ANSWER Volt-amperes
, Measuring velocity pressure in a duct indicates the _____. - ANSWER Speed at
which the air is moving
A solid material exerts a pressure or force _____. - ANSWER Downward only
Pure water boils at temperature of 213°F, at which of the following standard
conditions? - ANSWER 14.967psi
Which of the following would allow a system to operate more efficiently? -
ANSWER Condenser that had refrigerant leaving with 15°F of subcooling
One watt of electrical energy is equal to _____. - ANSWER 3.413 Btu
Rotary compressors are used primarily in _____. - ANSWER Domestic
refrigerators
The water circuit in shell and coil and coil-type tube-in-a-tube condensers must be
cleaned _____. - ANSWER Chemically
When a water regulating valve is used to control the head pressure of the water-
cooled system, the valve's spring is acting against which pressure to modulate the
waterflow? - ANSWER Head pressure of the system
The standard atmospheric pressure at sea level is _____. - ANSWER 29.92"
The steps to aggressively controlling the contamination of indoor air would involve
_____. - ANSWER All of the above (locating and eliminating the source of
contamination, providing adequate ventilation and providing methods for cleaning the
air)
If the resistance against a propeller fan is doubled, the cfm output decreases, but the
amperage draw of the motor _____. - ANSWER Increases
Which of the following re-presents a different temperature than the other three? -
ANSWER 475K
The best method of leak checking is when the refrigeration system is _____. -
ANSWER Standing with dry nitrogen pressure of 150 psig in the system
Technician "A" says that if the air filter on an air-conditioning system is totally
blocked with dirt, the amperage draw of the evaporator fan motor will go down.
Technician "B" says that if you close down one supply register on a duct system, the
volume of air feeding the other locations will increase slightly. Which of the following
statements is correct? - ANSWER Technician "A" is correct. Technician "B" is
correct.
The refrigerant in a refrigeration system changes state in the _____. - ANSWER
Condenser and evaporator
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