Chapter 1 Study Questions
Note: There is only one correct answer per question.
1. What is the purpose of a refrigeration system?
To freeze food.
To cool buildings.
To preserve food.
To maintain a temperature.
2. Operators must keep refrigeration systems operating safely and efficiently.
Which of the following best describes the areas of required knowledge for
this to be possible?
Basic physical principles, interpretation of information from
temperature and pressure gauges, basic operating principles.
Basic physical principles, interpretation of information from
temperature and pressure gauges, manufacturer of the equipment.
Interpretation of information from temperature and pressure gauges,
basic operating principles, company quality control policies and
procedures.
Interpretation of information from temperature and pressure gauges,
manufacturer of the equipment, company quality control policies and
procedures.
3. Mechanical refrigeration is a series of steps that
moves heat energy from a space or object to an area where it can do no
harm.
adds cold to a space or object.
transforms heat energy into cold energy to reduce the temperature of the
area to be cooled.
utilizes the cooling effect of compressing a gas to reduce the
temperature in a space or object.
4. Heat energy always flows
from a substance with more heat energy to a substance with less heat
energy.
regardless of temperature.
from an object at a higher temperature to an object at a lower
temperature.
from a liquid to a vapor.
5. Sensible heat
is measured using a pressure gauge.
is always between 32 and 212 degrees Fahrenheit.
is heat energy that causes a change of state but does not cause a change
in temperature.
is heat energy that causes a change in temperature but does not cause a
change of state.
6. Latent heat
is measured using a pressure gauge.
can be sensed by using a thermometer.
is heat energy that causes a change of state but does not cause a change
in temperature.
is heat energy that causes a change in temperature but does not cause a
change of state.
7. Which of the answers below is an example of heat transfer by convection?
The sun’s rays.
A rod that is heated on one end resulting in a temperature change at the
other end.
Warm air moving over an object.
Heat transferred to a pan setting on an electric hot plate.
8. How does the refrigeration technician/operator know what the conditions are
within a refrigeration system?
By using his knowledge of system basic operating principles to evaluate
temperature and pressure readings.
By observing the alarm annunciator panel, if no alarms are displayed the
system is operating efficiently and correctly.
By keeping the discharge and suction pressures within specification the
operator assures proper system operation.
By observing product temperature, if the product is at temperature the
system is operating properly.
9. What is the scale used to measure Fahrenheit temperature absolute?
Extreme
Rankine
Celsius
Kelvin
10.Which of the following is used to measure the quantity of heat energy?
British Thermal Units (BTUs) or calories.
Pascals and Kilopascals.
Degrees Kelvin.
Degrees Celsius or Fahrenheit.
11.Which of the following are used in heat calculations?
Mass, sensible heat, temperature, specific heat.
Mass, latent heat, temperature, specific heat.
Mass, sensible heat, heat of cooling, change of state.
Mass, latent heat, temperature, heat of refrigeration.
12.Latent heat of vaporization
is calculated using temperature.
is always going to raise the temperature of the liquid it is trying to boil.
is the heat energy required to cause a liquid to become a vapor.
is the same for all liquids.
13.Pressure is a measure of
the action seen from the attraction of gravity.
weight.
the relationship of a force being applied over a given area.
the distance between the top of the piston and the discharge valve of a
reciprocating compressor.
14.The relationship between temperature difference and heat flow is.
There is no relationship between temperature and heat flow.
The greater the temperature difference the slower heat flows.
The greater the temperature difference the more rapid the heat flows.
The more rapidly the heat flows the greater the temperature increases.
15.Specific heat
is greater as the substance requires more heat energy to increase
temperature.
is less as the substance requires more heat energy to increase
temperature.
is 1 BTU/lb./degree Fahrenheit for all substances.
is related to change of state, not temperature change of a substance.
16.Temperature is a measure of
the latent heat of an object.
heat of fusion that has been absorbed by an object.
heat of vaporization.
the intensity of the heat energy in an object.
17.If the force acting on an area of 5 square inches is 150 lb., what is the
pressure on the area?
30 lb./in2
750 lb./in2
155 lb./in2
3750 lb./in2.
18.Using the vapor pressure curve for ammonia, 70°F equals approximately.
38 psig.
40 psia.
70 psig.
114 psig.
19.Thirty-two psia equals
46.7 psig.
17.3 psig.
3.2 in. Hg Vacuum.
760 mm Hg.
20.The pressure midway between 0 psia and 0 psig is
7.35 psia.
7.35 psig.
7.35 in. Hg Vacuum.
0 in. Hg Vacuum.
21.Which of the answers below is an example of heat transfer by conduction?
The sun’s rays.
A rod heated on one end becoming warm at the other end.
Product being frozen in a blast freezer.
Heat felt from a campfire when standing upwind.
22.If specific heat for air is .24 BTU/lb./°F and the specific volume is 12.7 cu.
ft. / lb., how much heat energy must be removed to cool the air in a room
that is 16’ x 12’ x 8’ from 70°F to 40°F?
121
1,536
29
871
BTUs
BTUs
BTUs
BTUs
23.The condition of a boiling liquid is
Hot.
superheated.
subcooled.
saturated.
Use the information below when calculating answers for questions
38 and 39.
The Specific Heat of Some Materials
Water
Air 0.24
Iron
Copper
Wood
Sirloin Steak
Eggs
1.0
Ammonia
0.118
0.092
0.57
0.735
0.94
Potatoes
0.87
1.12
(Saturated liquid at 70 F)
Ice Cream
0.389
Milk
0.93
Cardboard
0.32
Concrete
0.156
24. A gallon of milk weighs 8 pounds. If it leaves the cow at 90°F and must be
cooled to 35°F, how many BTUs must be removed in the cooling process
409.2 BTU
40.9 BTU
440 BTU
51.15 BTU
25.A meat plant processes 100 animals a day with an average processed weight
of 750 pounds of beef per animal. The meat must be cooled to 45°F from
85°F. How many BTUs must be removed in the cooling process? (Use the
specific heat of sirloin steak.)
3,000,000
2,205,000
220,500
55,125
26.A vapor can NOT be
compressed.
superheated.
subcooled.
saturated.
27.What kind of a measure is a ton of refrigeration?
An amount in pounds.
A rate of heat transfer in BTUs per unit of time.
A quantity in BTUs.
A measure of energy in BTUs per pound.
28.Convert –6.7 degrees C to Fahrenheit?
32° F
20° F
-20° F
-12° F
29.What does the first Lat of Thermodynamics say?
a. Energy content only changes with a change in temperature
b. Energy in created when a substance is heated up.
c. Energy cannot be created or destroyed.
d. Total energy in a substance is a function of its physical size.
30.-40ºF is equal to
a. -40ºC
b. 40ºC
c. 0ºK
d. -32ºR
31.What is the freezing point of water?
a. -32ºF
b. 32ºC
c. 32ºF
d. 0ºF