Commercial and Domestic Refrigeration
Automatic pumpdown systems are equipped with a(n) _ to prevent refrigerant from reaching the evaporator.
solenoid
The three-way heat reclaim valves in most heat reclaim systems are ____ operated.
solenoid
controls use sound waves and vibrations, which are reflected back to the control from the ice.
sonar
is the best method of checking to see when a refrigerant coil has a proper level of refrigerant.
superheat
The one-time relief valve is caused to relieve by
temp
The refrigeration evaporator is a component that absorbs heat from the conditioned space into the refrigeration system.
true
It is recommended that at least _ a year, the probe should be removed from the water reservoir and cleaned.
twice
evaporators have ice cups designed to cause the ice to fall out of the cups during defrost.
vertical
SEER is calculated based on the total amount of cooling the system will provide over the entire season, divided by the total number of _ it will consume.
watts/hours
Random defrost is accomplished
when the refrigeration system has enough reserve capacity to cool more than the load requirement
The primary advantage of parallel compressor systems is their
nearly exact load matching ability
Low-temperature food storage applications generally start at
0°F
Knock-down walk-in coolers are constructed of interlocking panels from ____ thick.
1 in. to 4 in.
In condensate removal, the drain lines should be sloped downward about ____ in. per foot for proper drainage.
1/4
The refrigeration compressor motor can be operated at about ____% over its rated capacity without harm during the pulldown.
10
Refrigerated compressed air driers typically run ____% of the time.
100
When a parallel heat reclaim system is used, the heat reclaim condenser must be sized to handle ____% of the refrigeration system's rejected heat when in the heat reclaim mode.
100
As a rule of thumb, the temperature of the evaporator should be about _°F colder than the box temperature.
15
If an evaporator has a pressure drop of 10 psig and the low side pressure is 15 psig, what is the pressure at the inlet of the evaporator?
25 psig
The household refrigerator fresh-food compartment typically ranges from
28 to 40°F
Package ice machines store their own ice at ____ºF in a bin below the ice maker.
32
A typical evaporator operating temperature in an air-conditioning system is
40°F
Most package ice machines are designed to be located in ambient temperatures of
40ºF to 115ºF
High-temperature refrigeration applications will normally provide box temperatures of
47 to 60°F
A typical superheat for an evaporator operating under normal conditions would be
8 to 12°F
Which of the following is another type of low-ambient temperature head pressure control?
Air volume control using shutters and fan cycling.
One of the advantages of parallel compressor systems is
All of the above.
How does the receiver ensure that only 100% liquid refrigerant enters the liquid line?
By means of a dip tube.
To protect the compressor during periods of hot pull down, a(n) ____ valve is used.
CPR (crankcase pressure regulator)
When a system pumps down, where is the refrigerant stored?
Condenser and receiver.
For maximum efficiency, individual ice machine models have different programs called algorithms stored in their
EEPROM
The boiling temperature and its relationship to the system exist in the
Evaporators
A suction line accumulator is used to ensure that liquid refrigerant enters the compressor.
F
An open case is more efficient than a closed case.
F
Carbon dioxide (CO2) is one of the newest refrigerants.
F
Helical oil separators are about 58% efficient in separating oil.
F
Ice-making machines are the same as ice-holding machines such as those seen on the outside of a convenience store or service station.
F
The gear motor assembly is less prone to failure than any other part in the ice flaker.
F
sense the buildup of ice by infrared technology. This control allows the ice machine to shut down before the ice chokes the spout opening.
Infrared electric eyes
are simply small computers that contain stored programs or algorithms.
Microprocessors
evaporators are used when the coil would become too long for a single circuit,percent vapor.
Multicircuit
EPR valves are also referred to as ____ valves.
ORI
are snap-acting valves that open and close very fast when the electrical energy is applied to the coil.
Solenoid valves
A stamped plate evaporator usually does not use a fan to move air across it.
T
CO2, ammonia, propane, butane, and isobutane are all natural refrigerants.
T
Distributed supermarket refrigeration modules that are located very close to the display cases they refrigerate are becoming increasingly popular.
T
It is important that the auger does not wobble within the freezing cylinder or evaporator
T
Often, parallel compressor systems employ a satellite or booster compressor.
T
Oil separators work on the principle of low refrigerant and oil velocity.
T
Refrigerated air driers are normally self-contained refrigeration systems that may be air cooled or water cooled.
T
Self-contained equipment normally plugs into either a 120-V or 230-V electrical outlet.
T
Solid forms of ice last longer because there is more weight with less surface area.
T
The crankcase pressure regulator (CPR) puts a limit on the pressure that can return to the compressor.
T
The film factor is a relationship between the medium giving up heat and the heat-exchange surface.
T
To check the performance of a dry-type evaporator, the service technician would first make sure that the refrigerant coil is operating with enough liquid inside.
T
Two-temperature operation is desirable when more than one evaporator is used with a compressor.
T
When purchase cost alone is considered in selecting refrigeration equipment, the equipment may not perform acceptably.
T
Technician "A" says that a multi-evaporator system equipped with three evaporators (one high temperature, one medium temperature, and one low temperature) will use one evaporator pressure regulator and two flow check valves. Technician "B" says that the crankcase pressure regulator is used to keep the low-temperature compressor from overloading on a hot pulldown. Which of the following statements is correct?
Technician "A" is incorrect. Technician "B" is correct.
Refrigeration systems are designed to operate year round. For this reason they are equipped with
a low ambient control
At its triple point, CO2 can exist as ____.
all the above
The EPR valve is installed in the suction line at the evaporator outlet and it
all the above
Frequently on smaller condensing units, one fan will run continuously and the other fan will be cycled on and off with a(n)
ambient temperature controller
The normal position for a suction service valve during normal operation is
any of the 3
The ____ of the liquid refrigerant determines the coil operating temperature.
boiling temperature
All refrigeration equipment must have some means for disposing of the _ that is gathered on the evaporator.
condensate
Making a(n) _-shaped ice cube involves running water over an evaporator plate in which the copper evaporator tubing is soldered onto the plates at regular intervals.
crescent
If the application requires a coil design to operate below freezing, there must be provision for
defrost
the air means to remove the moisture, and this is frequently desirable in refrigeration systems.
dehumidifying
The air used for "pneumatic controls" must be
dry
A direct expansion-type evaporator is also called a
dry-type evaporator
The ____ in a refrigeration system is responsible for absorbing heat into the system from whatever medium is to be cooled.
evaporator
The _ is a mechanical control that keeps the refrigerant pressure in the evaporator from going below a predetermined point.
evaporator pressure-regulating valve (EPR valve)
Every central split cooling system manufactured in the USA today must have a Seasonal Energy Efficiency Ratio (SEER) of at least 10.
f
The capacity (tonnage) of the heat exchanger can vary with its height and depth.
false
Which of the following is a type of low-ambient temperature head pressure control?
fan cycling
Evaporators that are operated full of liquid and are equipped with a device to keep the liquid refrigerant from passing to the compressor are known as ____.
flooded evaporators
When the inside of the evaporator cabinet is below freezing, heat has to be provided to keep the condensate in the line _.
from freezing
Most ice flakers have a ____ that reduces the auger drive motor's speed from about 1725 rpm to 9 to 16 rpm.
gear reduction drive
A ____ is used to turn the auger in a flake ice machine.
geared motor
A refrigeration system designed for the storage of flowers or candy is considered a ____ type.
high temperature
One of the disadvantages of the secondary-fluid refrigeration systems is
higher cost of the equipment
A defrost system that pipes the compressor discharge vapor directly to the evaporator is called a(n) _ type.
hot gas defrost
Defrost using internal heat is accomplished using
hot gas from the compressor
The precharged tubing used for installing refrigeration piping is called a
line set
-temperature refrigeration produces temperatures below the freezing point of water.
low
To protect a refrigeration compressor when refrigerant loss occurs, a(n) _ control is used.
low pressure
The household refrigerator fresh-food compartment is a good example of ____ refrigeration.
medium-temp
Two-temperature operation of a refrigeration system is necessary when
more than one evaporator is used with a compressor
Heaters that are made with resistance-type wire run just under the surface of the cabinet are called ____ heaters.
mullion
The spring-loaded type of relief valve is normally brass with a(n) _ seat.
neoprene
Two types of relief valves are the spring-loaded valve and the _ valve.
one time
The heat reclaim valve is a three-way valve that is activated by a solenoid operated by a ____.
pilot
The most popular secondary fluid currently used in refrigeration systems is
propylene glycol
Retail stores use _ refrigeration units for merchandising their products.
reach in
are basically refrigeration systems located in the air supply, after the storage tank.
refrigerated air driers
The process of removing heat from a place where it is not wanted and transferring that heat to a place where it makes little or no difference is known as
refrigeration
In a kitchen, ____ condensing units may be easier to maintain.
remote
When the refrigerant vapor is saturated with heat it is known as a(n)
saturated vapor
The precharged tubing for refrigeration piping is _ at both ends and has quick connect fittings.
sealed
