refrigeration and air conditioning MCQs – Page 2

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

refrigeration and air conditioning Mcqs
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