Nj blue seal final exam study guide (Original) EXAM |Latest Update | Original
Questions & Answers with Detailed Rationales | Graded A+
Section 1: Refrigeration Systems & Operations
Q1. What is the main advantage of a cascade refrigeration
system?
A. It uses less refrigerant.
B. It is capable of reaching very low temperatures.
C. It requires no compressor.
D. It operates at a single pressure level.
Answer: B
Rationale: A cascade system uses two or more separate
refrigeration circuits with different refrigerants to achieve very
low temperatures that a single-stage system cannot efficiently
reach.
Q2. Choose the statement that would prove false about
lithium bromide used in an absorption system.
A. It is non-corrosive.
B. It is a strong absorber of water vapor.
C. It can crystallize if the temperature drops suddenly.
D. It is used as the absorbent in the system.
Answer: A
Rationale: Lithium bromide is highly corrosive to certain metals
,and requires corrosion inhibitors. It is not considered non-
corrosive. It is used as the absorbent in absorption refrigeration
systems.
Q3. What is a sling psychrometer device used to measure?
A. Absolute pressure
B. Relative humidity
C. Refrigerant charge
D. Compressor efficiency
Answer: B
Rationale: A sling psychrometer measures the dry-bulb and
wet-bulb temperatures to determine the relative humidity of
the air.
Q4. A system using an evaporative condenser operates most
efficiently under what conditions?
A. When the wet-bulb temperature of the air is high.
B. When the dry-bulb temperature of the air is low.
C. When the wet-bulb temperature of the air is low.
D. When the relative humidity is high.
Answer: C
Rationale: An evaporative condenser relies on the evaporation
of water to reject heat. Its efficiency is highest when the wet-
bulb temperature of the ambient air is low, as this promotes
better evaporation and heat transfer.
,Q5. If a refrigeration system were overcharged with
refrigerant, what conditions would occur?
A. Increase in capacity and decrease in head pressure.
B. Decrease in capacity and increase in head pressure.
C. No change in capacity or head pressure.
D. Increase in capacity and increase in head pressure.
Answer: B
Rationale: Overcharging a system with refrigerant reduces the
condensing surface area available for heat rejection, which
increases head pressure and decreases system capacity.
Q6. If a cooling tower circulated 4,300 GPM of water, what is
the cooling capacity in tons?
A. 1,433 tons
B. 4,300 tons
C. 1,000 tons
D. 2,150 tons
Answer: A
Rationale: A common rule of thumb for cooling towers is 3
GPM per ton of refrigeration. Therefore, 4,300 GPM / 3 =
approximately 1,433 tons.
Q7. What condition would cause a system to not respond to
an expansion valve adjustment?
A. Low refrigerant charge.
B. Oil in the evaporator.
, C. A faulty compressor.
D. High ambient temperature.
Answer: B
Rationale: Oil that has logged in the evaporator will insulate the
heat transfer surfaces, preventing the system from responding
properly to adjustments made at the expansion valve.
Q8. In an absorption system, the generator receives what
medium?
A. Weak liquor
B. Strong liquor
C. Pure refrigerant vapor
D. Cooling water
Answer: B
Rationale: In an absorption refrigeration cycle, the generator
receives "strong liquor" (a concentrated solution of absorbent
and refrigerant) from the absorber. Heat is applied in the
generator to drive off the refrigerant vapor.
Q9. What is the purpose of a water jacket on a system?
A. To increase the system's pressure.
B. To prevent thermal shock and remove heat.
C. To lubricate moving parts.
D. To filter out impurities.
Answer: B
Rationale: A water jacket surrounds a component (like a
Questions & Answers with Detailed Rationales | Graded A+
Section 1: Refrigeration Systems & Operations
Q1. What is the main advantage of a cascade refrigeration
system?
A. It uses less refrigerant.
B. It is capable of reaching very low temperatures.
C. It requires no compressor.
D. It operates at a single pressure level.
Answer: B
Rationale: A cascade system uses two or more separate
refrigeration circuits with different refrigerants to achieve very
low temperatures that a single-stage system cannot efficiently
reach.
Q2. Choose the statement that would prove false about
lithium bromide used in an absorption system.
A. It is non-corrosive.
B. It is a strong absorber of water vapor.
C. It can crystallize if the temperature drops suddenly.
D. It is used as the absorbent in the system.
Answer: A
Rationale: Lithium bromide is highly corrosive to certain metals
,and requires corrosion inhibitors. It is not considered non-
corrosive. It is used as the absorbent in absorption refrigeration
systems.
Q3. What is a sling psychrometer device used to measure?
A. Absolute pressure
B. Relative humidity
C. Refrigerant charge
D. Compressor efficiency
Answer: B
Rationale: A sling psychrometer measures the dry-bulb and
wet-bulb temperatures to determine the relative humidity of
the air.
Q4. A system using an evaporative condenser operates most
efficiently under what conditions?
A. When the wet-bulb temperature of the air is high.
B. When the dry-bulb temperature of the air is low.
C. When the wet-bulb temperature of the air is low.
D. When the relative humidity is high.
Answer: C
Rationale: An evaporative condenser relies on the evaporation
of water to reject heat. Its efficiency is highest when the wet-
bulb temperature of the ambient air is low, as this promotes
better evaporation and heat transfer.
,Q5. If a refrigeration system were overcharged with
refrigerant, what conditions would occur?
A. Increase in capacity and decrease in head pressure.
B. Decrease in capacity and increase in head pressure.
C. No change in capacity or head pressure.
D. Increase in capacity and increase in head pressure.
Answer: B
Rationale: Overcharging a system with refrigerant reduces the
condensing surface area available for heat rejection, which
increases head pressure and decreases system capacity.
Q6. If a cooling tower circulated 4,300 GPM of water, what is
the cooling capacity in tons?
A. 1,433 tons
B. 4,300 tons
C. 1,000 tons
D. 2,150 tons
Answer: A
Rationale: A common rule of thumb for cooling towers is 3
GPM per ton of refrigeration. Therefore, 4,300 GPM / 3 =
approximately 1,433 tons.
Q7. What condition would cause a system to not respond to
an expansion valve adjustment?
A. Low refrigerant charge.
B. Oil in the evaporator.
, C. A faulty compressor.
D. High ambient temperature.
Answer: B
Rationale: Oil that has logged in the evaporator will insulate the
heat transfer surfaces, preventing the system from responding
properly to adjustments made at the expansion valve.
Q8. In an absorption system, the generator receives what
medium?
A. Weak liquor
B. Strong liquor
C. Pure refrigerant vapor
D. Cooling water
Answer: B
Rationale: In an absorption refrigeration cycle, the generator
receives "strong liquor" (a concentrated solution of absorbent
and refrigerant) from the absorber. Heat is applied in the
generator to drive off the refrigerant vapor.
Q9. What is the purpose of a water jacket on a system?
A. To increase the system's pressure.
B. To prevent thermal shock and remove heat.
C. To lubricate moving parts.
D. To filter out impurities.
Answer: B
Rationale: A water jacket surrounds a component (like a
