Here are 1000 MCQs on Refrigeration and Air Conditioning (Chapterwise).
1. What is Refrigeration?
a) Refrigeration is the process of removing heat from a substance and cooling it to a temperature or below the actual temperature
b) Refrigeration is the process of adding heat from a substance and cooling it to a temperature
c) Refrigeration is used to increase the level of humidity in the air by adding heat
d) None of the mentioned
View Answer
Explanation: Refrigeration is the process of removing heat from a substance and cooling it to a temperature or below the actual temperature. The refrigeration unit is expressed in terms of a ton of refrigeration (TR).
2. How is the refrigerant used in the Air refrigeration cycle?
a) In the compressor
b) In the condenser
c) Directly in contact
d) Not used at all
View Answer
Explanation: Refrigerant used in Air refrigeration cycle is pure air, and it’s used directly in contact with the area of refrigeration. Whereas in Expansion refrigeration, refrigerants are used in condensers, etc…
3. Which of the following refers to the term C.O.P. of refrigeration?
a) Cooling for Performance
b) Coefficient of Performance
c) Capacity of Performance
d) Co-efficient of Plant
View Answer
Explanation: Coefficient of Performance is generally referred to as C.O.P. for Refrigeration, which is used to measure the capacity or level up to which the refrigeration will occur.
4. Which of the following is NOT the advantages of using a closed Air Refrigeration system?
a) Compact in construction
b) Lower coefficient of performance
c) Lighter in weight
d) Environmental Friendly
View Answer
Explanation: Air refrigeration system is used mainly due to light in weight, smaller and environment friendly due to use of air as a refrigerant. Also, it has a higher co-efficient of performance.
5. In lithium bromide absorption refrigeration system it is not necessary to keep the refrigeration temperature above 0°C.
a) False
b) True
View Answer
Explanation: In lithium bromide absorption refrigeration system it is necessary to keep the refrigeration temperature above 0°C as it is the freezing point of water. Water is used as a refrigerant in the system.
6. Which of the following is the S.I. unit to measure pressure in refrigeration?
a) Bar
b) Newton
c) Joule
d) Pascal
View Answer
Explanation: Generally, unit like N/mm2, N/m2, KN/mm2 and MN/mm2 etc. are used but the S.I. unit used is N/m2 i.e. Pascal.
7. Which of the following is the main disadvantage of natural refrigeration methods?
a) natural refrigeration methods are dependent on local conditions
b) natural refrigeration methods are not environment friendly
c) natural refrigeration methods are expensive
d) natural refrigeration methods are poisonous
View Answer
Explanation: Natural Refrigeration process is dependent on the local conditions like temperature of surrounding, pressure at which it occurs, and volume of the refrigerant, etc. hence it cannot be predicted exactly.
8. Which of the following is the result of a reduction in operating pressure in the Air refrigeration cycle?
a) decrease in C.O.P.
b) always decreases
c) increase in C.O.P.
d) no change in C.O.P.
View Answer
Explanation: As the operating pressure reduces, the change in work done decreases. Hence the C.O.P of refrigeration increases.
9. Which of the following is the key difference between a simple VAR and Electrolux refrigerator?
a) Working mechanism
b) Generator
c) Absorber
d) Liquid pump
View Answer
Explanation: Simple VAR uses a generator to do work as well as a pump to pressurize the liquid to the generator. So, total work done is the summation of work done by a pump and generator. The refrigeration effect is the heat absorbed in the evaporator. But as in the case of Electrolux refrigerator pump is not present. It is the VAR system with no liquid pump; hence, it is the key difference between Simple VAR and Electrolux refrigerators.
10. Efficiency of the Refrigerator is _________ to the C.O.P of the refrigerator.
a) independent
b) directly proportional
c) inversely proportional
d) equal
View Answer
Explanation: Efficiency is the ratio of work done to heat supplied, whereas C.O.P is the ratio of Refrigeration effect to work done. Hence it is totally independent quantity.
11. Which of the following will be the value of Refrigeration effect if m2 = 2 kg/min, m3 = 0.8 kg/min and enthalpies for the refrigerant at saturated vapor and saturated liquid line are 1420 and 1260 kJ/kg?
a) 129
b) 196
c) 194
d) 192
View Answer
Explanation: Given: m2 = 2 kg/min
m3 = 0.8 kg/min
h1 = 1420 kJ/kg and hf10 = h11 = 1260 kJ/kg
As, m1 = m2 – m3
= 2 – 0.8
= 1.2
Refrigeration effect = m1 (h1 – h11)
= 1.2 (1420 – 1260)
= 1.2 x 160
= 192 kJ/min.
12. Which of the following of the refrigerant is used as a refrigerant in Lithium Bromide Absorption Refrigeration system?
a) Lithium Bromide
b) Hydrogen
c) Water
d) Ammonia
View Answer
Explanation: Water is used as a refrigerant in Lithium Bromide Absorption Refrigeration system whereas lithium bromide, which is highly hydroscopic salt, is used as an absorbent. Lithium Chromate is used a corrosion inhibitor.
13. Which of the following refrigerants are used in Electrolux and Li-Br water refrigeration system?
a) Water and Bromide
b) Ammonia and Water
c) Ammonia and Lithium
d) Water and Water
View Answer
Explanation: In the Electrolux refrigerator, ammonia is used as a refrigerant, and in the case of Li-Br water system water is used as a refrigerant due to their desirable properties to produce refrigeration effect.
14. Which of the following will be the value of Refrigeration effect if m1 = 4 kg/min, and enthalpies for the point 1, 2, 4, 5, 9 are 1350, 1550, 1480, 1620, and 280 kJ/kg. If the refrigeration effect is 4280 kJ/min and work done is 15 kW, then what is the value of C.O.P.?
a) 4.75
b) 6.00
c) 5.50
d) 4.85
View Answer
Explanation: Given: m1 = 4 kg/min
h1 = 1350 kJ/kg
hf9 = h10 = 280 kJ/kg
h2 = 1550 kJ/kg
h4 = 1480 kJ/kg
h5 = 1620 kJ/kg
As, enthalpies of all points is given but it is a redundant data cause direct values of refrigeration effect and work is given, hence C.O.P. can be found easily.
Refrigeration effect = m1 (h1 – h11)
= 4280 kJ/min
Work = 15 kW = 900 kJ/min
C.O.P. = Refrigeration effect / Work
= 4280 / 900
= 4.75.
15. Which of the following is the common application of Air standard refrigeration system?
a) Cold storage
b) Car air conditioning system
c) Domestic refrigerators
d) Aircraft air conditioning
View Answer
Explanation: As a sufficient amount of air is obtained while aviation of air crafts, the only thing is to reduce its velocity, and then it can be used for air conditioning in air crafts.
16. What is Air Conditioning?
a) Air Conditioning is the process of adding heat and increasing the humidity
b) Air Conditioning is the process of removing heat and controlling the humidity of air in a closed space
c) Air conditioning is the process of controlling air moisture in an open area by adding heat
d) None of the mentioned
View Answer
Explanation: Air Conditioning is the process of removing heat and controlling the humidity of air in an enclosed space to achieve a more comfortable interior environment.
17. Which of the following process is used in winter air conditioning?
a) Cooling and Dehumidification
b) Heating and Humidification
c) Dehumidification
d) Humidification
View Answer
Explanation: In Winter, the weather is dry and cold, so the process of heating and humidification is done to get the desired comfort conditions.
18. On which of the following cycle the air conditioning systems are based in transport aviation?
a) Reversed Joule’s cycle
b) Otto cycle
c) Reversed Carnot cycle
d) Reversed Brayton cycle
View Answer
Explanation: It is because in vapor-cycle the disadvantage was that due to the leakage loss of fluid it would cause the aircraft to be complete without cooling.
19. Which of the following process is used in summer air conditioning?
a) Heating and Humidification
b) Cooling and Dehumidification
c) Humidification
d) Dehumidification
View Answer
Explanation: In Summer, the weather is humid and hot, so the process cooling and dehumidification is done to get the desired comfort conditions.
20. If the Coefficient of performance of a heat pump is 5, then what is the value of the Coefficient of performance of the refrigerator operating under the same conditions?
a) 0.2
b) 3
c) 4
d) 6
View Answer
Explanation: As we know, the equation between Coefficient of performance of Refrigerator and heat pump:
(C.O.P.)R = (C.O.P.)P − 1
Hence, C.O.P. of refrigerator = C.O.P. of heat pump − 1
= 5 − 1
= 4.
21. How is the cascade system achieved?
a) VCR system in a parallel combination
b) VCR system in a series combination
c) VAR system in a series combination
d) VAR system in a parallel combination
View Answer
Explanation: The cascade refrigeration system is structured by connecting two or more vapor compression refrigeration systems in series which use different refrigerants.
22. Dense air Bell-Coleman refrigerator is preferred over open cycle air refrigerator.
a) False
b) True
View Answer
Explanation: In open cycle air refrigerator the main drawback is the freezing of the moisture in the air during expansion stroke which is liable to choke up the valves. Hence dense air refrigerator is preferred.
23. In which of the following Capillary tube is used in as an expansion device?
a) Room air conditioners
b) Water coolers
c) Domestic refrigerators
d) All of the mentioned
View Answer
Explanation: The capillary tube as an expansion device is used in small capacity hermetic sealed refrigeration units such as in water coolers, domestic refrigerators and room air conditioners, etc.
24. Which of the following uses natural convection air-cooled condensers?
a) High capacity room air conditioners
b) Industrial air conditioners
c) Domestic refrigerators
d) High capacity water coolers
View Answer
Explanation: Natural convection phenomenon is used to carry out the operation. Large surface area is required for the proper heat transfer between the mediums. Due to the slow process and able to handle low capacity used just in small-capacity applications like domestic refrigerators.
25. Which of the following is the material of tubes used for shell and tube condenser in ammonia refrigeration system?
a) Copper
b) Steel
c) Brass
d) Aluminum
View Answer
Explanation: As ammonia is toxic and has the ability to rust the material which comes in the contact. So, in the ammonia refrigeration system, steel tubes are used for shell and tube condensers to avoid the corrosion.
26. Which of the following represents sensible cooling on the psychrometric chart?
a) Inclined line
b) Curve
c) Horizontal line
d) Vertical line
View Answer
Explanation: Sensible cooling is when DBT decreases. And as per the psychrometric chart, horizontal lines show the change in just DBT and represent sensible cooling.
27. Which of the following is the major equipment in the simplest form is used to do saturation of air?
a) Pipe
b) Chamber
c) Vessel
d) Insulated Chamber
View Answer
Explanation: The equipment used for saturation of the air in the simplest form is an insulated chamber containing an optimum amount of water.
28. Why is the evaporator used?
a) To absorb heat
b) To decrease the refrigeration effect
c) To reject heat
d) To improve C.O.P.
View Answer
Explanation: Evaporator is used to absorb the heat from the medium being cooled and get the refrigeration effect. Multiple evaporators are used to enhance the refrigeration effect and eventually the C.O.P. too.
29. Which of the following refrigerants is having the lowest C.O.P for refrigeration system working under the temperature limits of -15°C and 30°C as evaporator and condenser temperature respectively?
a) R – 12
b) Carbon dioxide
c) Ammonia
d) R – 30
View Answer
Explanation: Coefficient of performance is the ratio of refrigeration produced and work done to get that refrigeration effect. C.O.P. is a crucial entity. The more the C.O.P., more the refrigeration effect is produced, and lower temperatures can be achieved. Among the given options, Carbon dioxide is having least C.O.P. for given temperatures conditions, which is valued at 2.56. Whereas, Ammonia, R – 12 and R – 30 is having C.O.P. as 4.76, 4.70 and 4.90 respectively.
30. Which of the following type of refrigerants take a direct part in the refrigeration system?
a) Primary
b) Secondary
c) Tertiary
d) Mixed
View Answer
Explanation: Primary refrigerants are the one that takes a direct part in the refrigeration system. By absorbing the latent heat of vaporization effective refrigeration is produced.
Chapterwise Multiple Choice Questions on Refrigeration and Air Conditioning
- Vapour Refrigeration Cycles
- Vapour Refrigeration Systems
- Simple Vapour Compression Refrigeration Systems
- Compound Vapour Compression Refrigeration Systems
- Expansion Devices
- Vapour Absorption Refrigeration System
- Multiple Evaporators and Compressor System
- Refrigerants
- Refrigerant Compressors
- Condensers & Evaporators
- Psychrometric
- Comfort Conditions
- Air Conditioning Systems
1. Refrigeration and Air Conditioning MCQ on Vapour Refrigeration Cycles
The section contains Refrigeration and Air Conditioning multiple choice questions and answers on refrigeration units and performance, open air refrigeration system, heat pump, air refrigerator working on reverse carnot and bell coleman cycle.
2. Refrigeration and Air Conditioning Multiple Choice Questions on Vapour Refrigeration Systems
The section contains Refrigeration and Air Conditioning questions and answers on simple air cooling system, boot strap and regenerative air cooling system.
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3. Refrigeration and Air Conditioning MCQ on Simple Vapour Compression Refrigeration Systems
The section contains Refrigeration and Air Conditioning MCQs on simple vcr system mechanism, theoretical vcr with dry saturated vapour and superheated vapour after compression, actual vcr cycle, vcr system various parameters effect and pressure – enthalpy chart.
4. Refrigeration and Air Conditioning MCQ on Compound Vapour Compression Refrigeration Systems
The section contains Refrigeration and Air Conditioning multiple choice questions and answers on two multi stage compression with liquid intercooling, water intercooling and liquid subcooling, cascade systems and refrigerant reciprocating compressor performance characteristics.
5. Refrigeration and Air Conditioning MCQ on Expansion Devices
The section contains Refrigeration and Air Conditioning questions and answers on expansion devices.
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6. Refrigeration and Air Conditioning MCQ on Vapour Absorption Refrigeration System
The section contains Refrigeration and Air Conditioning MCQs on ideal var system and its performance, domestic electrolux and lithium bromide refrigeration system.
7. Refrigeration and Air Conditioning MCQ on Multiple Evaporators and Compressor System
The section contains Refrigeration and Air Conditioning multiple choice questions and answers on multiple evaporators and compressor system.
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8. Refrigerants MCQ
The section contains Refrigeration and Air Conditioning questions and answers on refrigerants classification, refrigerants designation system, refrigerants thermodynamic, physical and chemical properties.
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9. Refrigeration and Air Conditioning MCQ on Refrigerant Compressors
The section contains Refrigeration and Air Conditioning MCQs on multi stage compression, refrigerant compressors and its types.
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10. Refrigeration and Air Conditioning MCQ on Condensers & Evaporators
The section contains Refrigeration and Air Conditioning multiple choice questions and answers on condensers, cooling towers, evaporators types, factors and defrosting methods.
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11. Refrigeration and Air Conditioning MCQ on Psychrometry
The section contains Refrigeration and Air Conditioning questions and answers on psychrometric terms and relations, psychrometric chart, thermodynamic wet bulb temperature, bypass factor, heating and cooling factor, partial pressure daltons law, two streams adiabatic mixing, humidification and dehumidification.
12. Refrigeration and Air Conditioning MCQ on Comfort Conditions
The section contains Refrigeration and Air Conditioning MCQs on optimum effective temperature, human body heat production and rejection.
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13. Refrigeration and Air Conditioning Multiple Choice Questions on Air Conditioning Systems
The section contains Refrigeration and Air Conditioning multiple choice questions and answers on comfort air conditioning, air conditioning systems equipments, industrial air-conditioning, winter and summer air-conditioning, unitary and central air conditioning, room and grand sensible heat factors, fans and its laws.
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Wish you the best in your endeavor to learn and master Refrigeration and Air Conditioning!
Important Links:
- Refrigeration and Air Conditioning Books
- Refrigeration Systems Books
- Basic Refrigeration Technology Books
- Air Conditioning and Ventilation Books
- Mechanical Engineering Multiple Choice Questions
