Refrigeration and Air Conditioning 1

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Mechanical Engineering MCQ Question Papers: DRDO, ISRO, Interview

Subject: Refrigeration and Air Conditioning 1

Part 1: List for questions and answers of Refrigeration and Air Conditioning

Q1. In a mechanical refrigeration system the highest temperature of refrigerant occurs
a) Between condenser and evaporator
b) In evaporator
c) Before expansion valve
d) Between compressor and condenser

Q2. As warm air cools, its
a) Relative humidity increases
b) Relative humidity decreases
c) Capacity to hold moisture increases
d) Dew point occurs

Q3. When the air temperature reaches the point where relative humidity is 100% the air is saturated because it cannot hold any more moisture. This temperature is called
a) Freezing point
b) Dew point
c) Dew point of water vapour
d) Dew point of air

Q4. Defrosting of evaporators is done because
a) Frosting is undesirable
b) Frosting increases refrigerating effect
c) Frosting obstructs flow of refrigerant
d) Frosting may cause damage to equipment

Q5. The chemical formula for Freon-12 is
a) CHCIF2
b) CH3CL
c) CCIF3
d) CCIF2CF3

Q6. Of the following chemicals the liquid having the greatest cooling effect on an individual is
a) Water
b) Ether
c) Water containing ammonium hydroxide
d) Alcohol

Q7. In a refrigeration cycle the heat is rejected by refrigerant at
a) Evaporator
b) Condenser
c) Compressor
d) All of the above

Q8. The flow of the refrigerant in a refrigeration cycle is controlled by
a) Compressor
b) Evaporator
c) Expansion valve
d) Copper tubing

Q9. Sub-cooling is
a) Cooling a part of liquid
b) Differential cooling of a liquid
c) Removing sensible heat from a liquid
d) Cooling a liquid below 0?

Q10. An increase in the movement of the molecules within a solid, liquid or gas corresponds to
a) A drop in temperature
b) No change in temperature
c) A rise in temperature
d) None of the above

Q11. In a mechanical refrigeration system the refrigerant occurs as liquid (or very wet vapour) between
a) Compressor outlet and condenser
b) Condenser and expansion valve
c) Evaporation valve and compressor
d) Before and after compressor

Q12. A device designed to remove moisture from a refrigerant is called
a) Expansion valve
b) Dehumidifier
c) Drier
d) Humidistat

Q13. A desicant is
a) A solid substance capable of removing moisture from a gas, liquid or solid
b) A substance which reduces the viscosity of liquids
c) A process of removing heat under controlled conditions
d) An ammonia and a water solution

Q14. Freon 12 is a compound consisting of stoms of
a) Carbon, hydrogen and fluorine
b) Carbon, hydrogen, fluorine and chlorine
c) Carbon, fluorine and chlorine
d) Carbon and hydrogen

Q15. The condition of refrigerant before and after the expansion or throttle valve in a vapour compression system is
a) Wet vapour, very wet vapour
b) High pressure saturated liquid, very wet vapour
c) Very wet vapour, high pressure, saturated liquid
d) None of the above

Q16. In vapour absorption refrigeration system the power is required for vapour
compressor as compared to that in vapour compression cycle is
a) More
b) Half
c) One forth
d) There is no such relation

Q17. In a ammonia vapour compression cycle during gas charging the connection is made
a) Anywhere in the cycle
b) At the compressor cycle
c) On low pressure side near evaporate
d) On high pressure side close to receiver

Q18. In a newly charged ammonia compression system, the clicking sound in the expansion valve indicates
a) High pressure after compression
b) Excessive ammonia charged
c) Lack of ammonia
d) Leakage of ammonia

Q19. Air and other non-condensable gases (foul gases) get into a refrigeration system through
a) Decomposition of refrigerant in contact with impurities
b) Breakdown of oil
c) Under vacuum operation or during maintenance work
d) Any of the above

Q20. A plant has one 300 ton and one 500 ton centrifugal unit. The total flow of brine is 6400 litres per minute. What should be the distribution of brine flow through each unit?
a) 3200 litres each
b) 2400 litres through 300 ton plant and 4000 litres through 500 ton plant
c) 4000 litres through 300 ton plant and 2400 litres through 500 ton plant
d) Same brine should flow through both

Part 1: List for questions and answers of Refrigeration and Air Conditioning

Q1. Answer: d

Q2. Answer: b

Q3. Answer: b

Q4. Answer: d

Q5. Answer: a

Q6. Answer: d

Q7. Answer: b

Q8. Answer: c

Q9. Answer: a

Q10. Answer: c

Q11. Answer: b

Q12. Answer: c

Q13. Answer: a

Q14. Answer: c

Q15. Answer: b

Q16. Answer: d

Q17. Answer: d

Q18. Answer: c

Q19. Answer: d

Q20. Answer: c