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refrigeration and air conditioning MCQs

Practise focused refrigeration and air conditioning questions with marked answers for exam preparation and subject revision.

refrigeration and air conditioning Mcqs
1. In vapour compression cycle, the conditii of refrigerant is saturated liquid________________?
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A. before entering the expansion valve

B. after passing through the expansion throttle valve

C. before entering the compressor

D. after passing through the condenser

E. before passing through the condensei

2. Most of the domestic refrigerators work on the following refrigeration system _________________?
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A. vapour compression

B. electrolux refrigerator

C. dual cycle

D. carnot cycle

E. vapour absorption

3. Allowable pressure on high-pressure side or ammonia absorption system is of the order of_________________?
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A. 2-4 bars

B. 7-10 bars

C. 5-6 bars

D. atmospheric pressure

E. slightly above atmospheric pressure

4. If a heat pump cycle operates between the condenser temperature of +27C and evaporator temperature of 23C, then the Carnot COP will be_________________?
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A. 1.2

B. 6

C. 10

D. 0.2

E. 5

5. Aqua ammonia is used as refrigerant in the following type of refrigeration system_________________?
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A. compression

B. direct

C. absorption

D. none of the above

E. indirect

6. In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is_____________________?
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A. there is no such consideration

B. pone of the above

C. more than or equal to 3.65 kg

D. less than 2 kg

E. more than 10 kg

7. A refrigerant should have _____________________?
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A. Tow specific heat of liquid

B. low specific volume of vapour

C. k up the wrong statement ?

D. high latent heat of vaporisation

E. higher critical temperature

F. high boiling point
8. One ton refrigeratiqn corresponds to_________________?
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A. 50 kcal/min

B. 80 kcal/min

C. 80 kcal/hr

D. 50 kcal/kr

E. 1000 kcal/day

9. A refrigeration cycle operates between condenser temperature of + 27C and evaporator temperature of- 23C. The Cannot coefficient of performance of cycle will be_________________?
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A. 6

B. 5

C. 0.2

D. 10

E. 1.2

10. Critical temperature is the temperature above which _____________________?
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A. none of the above

B. water will evaporate

C. a gas will immediately liquefy

D. water will never evaporate

E. a gas will never liquefy
11. The COP of a domestic refrigerator___________________?
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A. is equal to 1

B. depends upon the make

C. is less than 1

D. is more than 1

E. depends upon the weather conditions

12. The refrigeration effect in a dry evaporator compared to flooded evaporator in a similar plant is_________________?
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A. unpredictable

B. same

C. more or less depending on ambient conditions

D. more

E. less
13. The evolution of heat of solution takes place in ammonia absorption plant when _____________________?
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A. lithium bromide is driven out of solution

B. lithium bromide mixes with ammonia

C. ammonia vapour goes into solution

D. ammonia vapour is driven out of solution

E. weak solution mixes with strong solution

14. Vertical lines on pressure-enthalpy chart show constant_______________?
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A. pressure lines

B. volume lines

C. total heat lines

D. temperature lines

E. entropy lines

15. The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will______________________?
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A. increase

B. unpredictable

C. remain unaffected

D. may increase or decrease depending on the type of refrigerant used

E. decrease

16. Clapeyron equation is applicable for registration at___________________?
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A. saturation point of vapor

B. saturation point of liquid

C. critical point

D. sublimation temperature

E. triple point

17. Presence of moisture in a refrigerant affects the working of___________________?
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A. expansion valve

B. heat transfer

C. evaparator

D. compressor

E. condenser

18. For obtaining high COP, the pressure range of compressor should be_______________?
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A. low

B. high

C. any value

D. there is no such criterion

E. optimum

19. In vapor compression cycle, the condition of refrigerant is very wet vapor________________?
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A. before entering the expansion valve

B. after passing through the condenser

C. before entering the compressor

D. before passing through the condenser

E. after passing through the expansion or throttle valve

20. The bank of tubes at the back of domestic refrigerator are _________________?
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A. condenser tubes

B. refrigerant cooling tubes

C. capillary tubes

D. evaporator tubes

E. throttling device

21. For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then_________________?
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A. perfectly tight vapour seal should be used

B. smaller cabinet should be used

C. refrigerant with high boiling point must be used

D. refrigerant with lower evaporation temperature should be used

E. bigger cabinet should be used

22. Vapor compression refrigeration is some what like ____________________?
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A. Rankine cycle

B. reversed Camot cycle

C. none of the above

D. reversed Rankine cycle

E. Carnot cycle

23. In vapor compression cycle, the condition of refrigerant is high pressure saturated liquid________________?
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A. before entering the expansion valve

B. after passing through the condenser

C. before passing through the condenser

D. before entering the compressor

E. after passing through the expansion or thiottle valve

24. In S.J. unit, one ton of refrigeration is equal to___________________?
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A. 210 kJ/min

B. 420 kJ/min

C. 840 kJ/min

D. 105 kJ/min

E. 21 kJ/min

25. Condensing temperature in a refrigerator is the temperature_________________?
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A. at which refrigerant gas becomes liquid

B. of evaporator

C. of freezing zone

D. of cooling medium

E. condensing temperature of ice

26. Ammonia-absorption refrigeration cycle requires__________________?
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A. none of the above

B. zero work input

C. maximum work input

D. very little work input

E. nearly same work input as for vapour compression cycle

27. Which of the following cycles uses air as the refrigerant__________________?
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A. Bell-coleman

B. Carnot

C. Ericsson

D. Stirling

E. none of the above

28. One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice_________________?
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A. in 10 hours

B. in 1 minute

C. in 1 hour

D. in 24 hours

E. in 12 hours

29. Rating of a domestic refrigerator is of the order of__________________?
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A. 5 tons

B. 10 tons

C. 40 tons

D. 0.1 ton

E. 100 tons

30. In vapour compression cycle the condition of refrigerant is superheated vapour _____________________?
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A. before entering the compressor

B. after passing through the expansion or throttle valve

C. after passing through the condenser

D. before passing through the condenser

E. before [entering the expansion valve

31. Clapeyron equation is a relation between___________________?
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A. temperature, pressure, and specil volume

B. specific volume and enthalpy

C. temperature, pressure, specific volur andenthalpy

D. temperature, pressure and enthalpy

E. temperature and enthalpy

32. The boiling point of ammonia is___________________?
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A. 33.3C

B. 33.3C

C. -50C

D. -100C

E. 0C

33. The value of COP in vapour compression cycle is usually__________________?
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A. none of the above

B. always more than unity

C. equal to unity

D. always less than unity

E. any one of the above

34. The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is_________________?
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A. bigger

B. smaller/bigger depending on capacity

C. unpredictable

D. smaller

E. equal

35. A standard ice point temperature corresponds to the temperature of ___________________?
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A. mixture of ice, water and vapour under equilibrium conditions under NTP conditions

B. solid and dry ice

C. water at 0C

D. mixture of ice and water Under equilibrium conditions

E. ice at 4C

36. The relative coefficient of performance is_____________________?
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A. 1-actual COP x theoretical COP

B. 1-actual COP/fheoretical COP.

C. actual COP/fheoretical COP

D. theoretical COP/actual COP

E. actual COP x theoretical COP

37. Efficiency of a Carnot engine is given as 80%. If the- cycle direction be reversed, what will be the value of COP of reversed Carnot cycle_________________?
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A. 0.8

B. 0.5

C. 0.25

D. 1.25

E. none of the above

38. The leaks in a refrigeration system using Freon are detected by____________________?
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A. halide torch which on detection produces greenish flame lighting

B. smelling

C. sulphur sticks which on detection gives white smoke

D. sensing reduction in pressure

E. using reagents

39. Ammonia is __________________?
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A. non-inflammable

B. non-toxic

C. toxic and non-inflammable

D. none of the above

E. highly toxic and inflammable
40. Moisture in freon refrigeration system causes________________?
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A. corrosion of whole system

B. ineffective refrigeration

C. breakdown of refrigerant

D. freezing automatic regulating valve

E. high power consumption

41. On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process ________________?
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A. takes place at constant enthalpy

B. takes place at constant pressure

C. takes place at constant temperature

D. involves no change in volume

E. takes place at constant entropy

42. Short horizontal lines on pressure-enthalpy chart show__________________?
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A. constant volume lines

B. constant entropy lines

C. constant total heat lines

D. constant pressure lines

E. constant temperature lines

43. An important characteristic of absorption system of refrigeration is__________________?
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A. quiet operation

B. its input only in the form of heating

C. cooling below 0C

D. noisy operation

E. very little power consumption

44. Which of the following refrigerants has lowest freezing point_______________?
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A. Freon-22

B. Freon-12

C. NH3

D. S02

E. C02

45. The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P_____________________?
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A. none of the above

B. unpredictable

C. more

D. equally.

E. less

46. Accumulators should have adequate volume to store refrigerant charge at least_________________?
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A. 50%

B. 25%

C. 100%

D. 10%

E. 75%

47. In vapour compression cycle using NH3 as refrigerant, initial charge is filled at_________________?
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A. low pressure side near receiver

B. anywhere in the cycle

C. high pressure side close to receiver

D. delivery of compressor

E. suction of compressor

48. The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will__________________?
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A. may increase or decrease depending on the type of refrigerant used

B. unpredictable

C. remain unaffected

D. increase

E. decrease

49. Air refrigeration cycle is used in ____________________?
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A. commercial refrigerators

B. such a cycle does not exist

C. gas liquefaction

D. domestic refrigerators

E. air conditioning

50. The advantage of dry compression is that________________?
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A. none of the above

B. it permits higher speeds to be used

C. it permits complete evaporation in the evaporator

D. all of the above

E. it results in high volumetirc and mechanical efficiency