Unit 36: Review Questions
Each degree of condenser subcooling will increase system efficiency by approximately how much?
1%
Multicircuit evaporators are equipped with which of the following components?
A refrigerant distributor located at the outlet of the metering device.
Air-conditioning is classified as which type of refrigeration?
High temperature
On average, each ton of system capacity has the ability to remove approximately how much moisture from the air?
One quart
Which of the following best describes the scrolls in a scroll compressor?
One scroll is stationary and one scroll orbits.
What refrigerant lines are field installed on the typical package-type air-conditioning unit?
Package-type equipment has no field-installed refrigerant lines.
As refrigerant undergoes the compression process
the pressure and temperature of the refrigerant increase.
Discharge gas temperature is affected most by
the temperature of the suction gas.
All of the following are true regarding the scroll compressor except
there is a clearance volume that traps some refrigerant.
If a duct system is uninsulated and runs through the conditioned space
there will be no net duct losses while the system is operating in either the cooling or heating mode.
Air-conditioning is often referred to as
comfort cooling.
Radial sealing on a scroll compressor is typically accomplished with
oil.
The 1% design wet-bulb and dry-bulb temperatures for Napa, California in the summer are
100°F dry-bulb, 71°F wet-bulb.
Which of the following is a possible condenser saturation temperature for an R-410A air-conditioning system that is operating with an outside ambient temperature of 90°F?
120°F
The maximum desired discharge line temperature for an R-410A compressor is
175°F.
What feature on a thermostatic expansion valve allows the system pressures to equalize during the off-cycle?
Bleed port
Heat leaks into a structure by which three methods?
Conduction, infiltration, and radiation
Which of the following best describes the air that enters the structure after being treated by an evaporative cooler?
Cool and humid
Which of the following best describes the refrigerant at the outlet of the condenser?
High-pressure liquid
Evaporative cooling systems are best-suited for which type of climate?
Hot, dry climate
What refrigerant lines are field installed on the typical split-type air-conditioning system?
Liquid line and suction line
Which of the following is true regarding the rotary compressor?
There is no clearance volume on these compressors.
The temperature of the evaporator coil is affected
by both the temperature and amount of air passing through the coil
The condensing unit of a split-type air-conditioning system is made up of the
condenser coil and compressor.
Package-type air-conditioning units are intended to be located
either on the roof of a structure or at ground level.
Thermostatic expansion valves are designed to maintain constant
evaporator superheat.
Reciprocating compressors used in residential applications are most likely to be
fully hermetic, suction-gas-cooled pumps.
A typical multihead, ductless split system is configured with
multiple indoor units and one outdoor unit.
Rotary compressors are built with
only discharge valves.
The compressor type that relies on pistons moving up and down within cylinders is the
reciprocating compressor.
The two types of heat transfer that are facilitated by the evaporator are
sensible heat and latent heat.
Three common evaporator coil configurations found on air-conditioning systems are
slant, A, and H.
The refrigerant that both enters and leaves a properly operating compressor can best be described as
superheated vapor.
prevent the vapor refrigerant in the line from absorbing additional, unwanted heat.
prevent the vapor refrigerant in the line from absorbing additional, unwanted heat.
When sizing and selecting air-conditioning equipment, which of the following must be taken into account?
Moisture content
At or near design conditions the supply and return temperatures for an air-conditioning system are closest to
55°F supply air, 75°F return air.
