Thermodynamics Questions and Answers – Vapor Compression Refrigeration Cycle-2

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This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Vapor Compression Refrigeration Cycle-2”.

1. Which of the following statement is true for a condenser?
a) it can be air-cooled or water-cooled
b) small self-contained units use water-cooled condenser
c) large installations use air-cooled condenser
d) all of the mentioned
View Answer

Answer: a
Explanation: We use air-cooled condenser for small self-contained units and water-cooled condenser for large installations.
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2. For an expansion device, which of the following is true?
a) it increases the pressure of refrigerant
b) it regulates the flow of refrigerant to evaporator
c) both of the mentioned
d) none of the mentioned
View Answer

Answer: b
Explanation: The expansion device reduces the pressure of refrigerant.

3. Which of the following is a type of expansion device?
a) capillary tubes
b) throttle valves
c) both of the mentioned
d) none of the mentioned
View Answer

Answer: c
Explanation: These are the two types of expansion devices.
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4. Throttle valves are used in ____
a) small units
b) larger units
c) both of the mentioned
d) none of the mentioned
View Answer

Answer: b
Explanation: They regulate the flow of refrigerant according to load on evaporator.

5. Capillary tubes are used in ____
a) small units
b) larger units
c) both of the mentioned
d) none of the mentioned
View Answer

Answer: a
Explanation: In their case, id size and length are fixed, the evaporator pressure also gets fixed.
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6. Types of compressor include
a) reciprocating
b) centrifugal
c) rotary
d) all of the mentioned
View Answer

Answer: d
Explanation: These are the three types of compressor.

7. When volume flow rate of refrigerant is large, which compressor is used?
a) reciprocating
b) centrifugal
c) rotary
d) all of the mentioned
View Answer

Answer: b
Explanation: For plants with higher capacities, centrifugal compressors are used.
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8. Which of the following statement is true?
a) rotary compressors are mostly used for small units
b) reciprocating compressors are employed in plants with capacity up to 100 tonnes
c) both of the mentioned
d) none of the mentioned
View Answer

Answer: c
Explanation: This is the difference in reciprocating and rotary compressors.

9. In reciprocating compressors, actual volume of gas drawn in cylinder is ____ the volume displaced by piston.
a) less than
b) more than
c) equal to
d) none of the mentioned
View Answer

Answer: a
Explanation: The reason being, leakage, clearance and throttling effects.
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10. The clearance volumetric efficiency is equal to
a) 1 + C + C(p2/p1)^(1/n)
b) 1 – C – C(p2/p1)^(1/n)
c) 1 – C + C(p2/p1)^(1/n)
d) 1 + C – C(p2/p1)^(1/n)
View Answer

Answer: d
Explanation: Here C is the clearance and p1,p2 are pressures.

11. Plate evaporator is a common type of evaporator.
a) true
b) false
View Answer

Answer: a
Explanation: In a plate evaporator, a coil is brazed on to a plate.

12. Why is multistage compression with intercooling adopted?
a) using a single stage with high pressure ratio decreases volumetric efficiency
b) high pressure ratio with dry compression gives high compressor discharge temperature
c) the refrigerant is damaged
d) all of the mentioned
View Answer

Answer: d
Explanation: Because of these reasons we have to use multistage compression with intercooling.

13. The intercooler pressure is given by
a) p1*p2
b) sqrt(p1*p2)
c) (p1*p2)/(p1+p2)
d) (p1+p2)/2
View Answer

Answer: b
Explanation: Here p1 is the evaporator pressure and p2 is the condenser pressure.

14. The most widely used refrigerants are
a) freon
b) genetron
c) arcton
d) all of the mentioned
View Answer

Answer: d
Explanation: These are a group of halogenated hydrocarbons.

15. Why is ammonia used in food refrigeration?
a) high COP
b) low cost
c) lower energy cost
d) all of the mentioned
View Answer

Answer: d
Explanation: Also ammonia can be detected easily in case of a leak.

Sanfoundry Global Education & Learning Series – Thermodynamics.
To practice all areas of Thermodynamics, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter