IIFT - Refrigeration & Air-Conditioning 1000+ MCQ [Solved] PDF Download

1. During humidification process, dry bulb temperature
A. Remains constant
B. Increases
C. Decreases
D. None of these
Answer : A

2. During dehumidification process, the relative humidity
A. Remains constant
B. Increases
C. Decreases
D. None of these
Answer : C

3. For unsaturated air, the dew point temperature is __________ wet bulb temperature.
A. Equal to
B. Less than
C. More than
D. None of these
Answer : B

4. The difference between dry bulb temperature and wet bulb temperature, is called
A. Dry bulb depression
B. Wet bulb depression
C. Dew point depression
D. Degree of saturation
Answer : B

5. A good refrigerant should have
A. High latent heat of vaporisation and low freezing point
B. High operating pressures and low freezing point
C. High specific volume and high latent heat of vaporisation
D. Low C.O.P. and low freezing point
Answer : A

6. In case of sensible heating of air, the coil efficiency is given by (where B.P.F. = Bypass factor)
A. B.P.F. - 1
B. 1 - B. P.F.
C. 1/ B.P.F.
D. 1 + B.P.F.
Answer : B

7. Dry bulb temperature is the temperature of air recorded by a thermometer, when
A. It is not affected by the moisture present in the air
B. Its bulb is surrounded by a wet cloth exposed to the air
C. The moisture present in it begins to condense
D. None of the above
Answer : A

8. In vapour compression cycle, the condition of refrigerant is very wet vapour
A. After passing through the condenser
B. Before passing through the condenser
C. After passing through the expansion or throttle valve
D. Before entering the compressor
Answer : D

9. Most air cooled condensers are designed to operate with a temperature difference of
A. 5°C
B. 8°C
C. 14°C
D. 22°C
Answer : C

10. The COP of a domestic refrigerator
A. Is less than 1
B. Is more than 1
C. Is equal to 1
D. Depends upon the make
Answer : B

11. Chaperon equation is a relation between
A. Temperature, pressure and enthalpy
B. Specific volume and enthalpy
C. Temperature and enthalpy
D. Temperature, pressure, specific volume and enthalpy
Answer : D

12. The sensible heat factor during the heating and humidification process is given by (where h? = Enthalpy of air entering the heating coil, h? = Enthalpy of air leaving the heating coil, and hA = Enthalpy of air at the end of humidification process)
A. (hA - h2)/ (h1 - h2)
B. (h2 - hA)/ (h1 - h2)
C. (h1 - h2)/ (hA - h2)
D. (hA - h1)/ (h2 - h1)
Answer : D

13. The dehumidification process, on the psychrometric chart, is shown by
A. Horizontal line
B. Vertical line
C. Inclined line
D. Curved line
Answer : B

14. The higher temperature in vapour compression cycle occurs at
A. Receiver
B. Expansion valve
C. Evaporator
D. Compressor discharge
Answer : D

15. The bypass factor for a cooling coil
A. Increases with increase in velocity of air passing through it
B. Decreases with increase in velocity of air passing through it
C. Remains unchanged with increase in velocity of air passing through it
D. May increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering
Answer : A

16. Short horizontal lines on pressure-enthalpy chart show
A. Constant pressure lines
B. Constant temperature lines
C. Constant total heat lines
D. Constant entropy lines
Answer : A

17. In a saturated air-water vapour mixture, the
A. Dry bulb temperature is higher than wet bulb temperature
B. Dew point temperature is lower than wet bulb temperature
C. Dry bulb, wet bulb and dew point temperature are same
D. Dry bulb temperature is higher than dew point temperature
Answer : C

18. The leaks in a refrigeration system using Freon are detected by
A. Halide torch which on detection produces greenish flame lighting
B. Sulphur sticks which on detection gives white smoke
C. Using reagents
D. Smelling
Answer : A

19. The wet bulb temperature at 100% relative humidity is ________ dry bulb temperature.
A. Same as
B. Lower than
C. Higher than
D. None of these
Answer : A

20. An infinite parallel planes with emissivities e? and e?, the interchange factor for radiation from surface 1 to surface 2 is given by
A. (e? + e?)/ e? + e? - e?e?
B. 1/e? + 1/e?
C. e? + e?
D. e?e?
Answer : A

21. Aqua ammonia is used as refrigerant in the following type of refrigeration system
A. Compression
B. Direct
C. Indirect
D. Absorption
Answer : D

22. In a pressure enthalpy chart, the space to the left of the saturated liquid line represents
A. Wet vapour region
B. Superheated vapour region
C. Sub-cooled liquid region
D. None of these
Answer : C

23. The human body feels comfortable when the heat stored in the body is
A. Positive
B. Negative
C. Zero
D. None of these
Answer : C

24. The thermostatic expansion valve is used in __________ type of evaporators.
A. Flooded
B. DX coil
C. Dry
D. None of these
Answer : C

25. The humidification process, on the psychrometric chart is shown by
A. Horizontal line
B. Vertical line
C. Inclined line
D. Curved line
Answer : B

26. The alignment circle is marked on the psychrometric chart at
A. 20°C DBT and 50% RH
B. 26°C DBT and 50% RH
C. 20°C DBT and 60% RH
D. 26°C DBT and 60% RH
Answer : B

27. As relative humidity decreases, the dew point temperature will be ________ wet bulb temperature.
A. Same as
B. Lower than
C. Higher than
D. None of these
Answer : B

28. The relative humidity lines on a psychrometric chart are
A. Vertical and uniformly spaced
B. Horizontal and uniformly spaced
C. Horizontal and non-uniformly spaced
D. Curved lines
Answer : D

29. The coefficient of performance is the ratio of the refrigerant effect to the
A. Heat of compression
B. Work done by compressor
C. Enthalpy increase in compressor
D. All of the above
Answer : D

30. Bell Coleman cycle is a
A. Reversed Carnot cycle
B. Reversed Otto cycle
C. Reversed Joule cycle
D. Reversed Rankine cycle
Answer : C

31. One ton refrigeration corresponds to
A. 50 kcal/ min
B. 50 kcal/ hr
C. 80 kcal/ min
D. 80 kcal/ hr
Answer : A

32. The refrigerant widely used in domestic refrigerators is
A. Ammonia
B. Carbon dioxide
C. Sulphur dioxide
D. R-12
Answer : D

33. The index which correlates the combined effects of air temperature, relative humidity and air velocity on the human body, is known as
A. Mean radiant temperature
B. Effective temperature
C. Dew point temperature
D. None of these
Answer : B

34. Freon group of refrigerants are
A. Inflammable
B. Toxic
C. Non-inflammable and toxic
D. Nontoxic and non-inflammable
Answer : D

35. During dehumidification process, __________ remains constant.
A. Wet bulb temperature
B. Relative humidity
C. Dry bulb temperature
D. Specific humidity
Answer : C

36. The ratio of heat extracted in the refrigerator to the work-done on the refrigerant is called
A. Coefficient of performance of refrigeration
B. Coefficient of performance of heat pump
C. Relative coefficient of performance
D. Refrigerating efficiency
Answer : A

37. The bank of tubes at the back of domestic refrigerator is
A. Condenser tubes
B. Evaporator tubes
C. Refrigerant cooling tubes
D. Capillary tubes
Answer : A

38. The cooling system used for supersonic aircrafts and rockets is
A. Simple air cooling system
B. Bootstrap air cooling system
C. Reduced ambient air cooling system
D. Regenerative air cooling system
Answer : D

39. For better C.O.P of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be
A. Small
B. High
C. Equal
D. Anything
Answer : A

40. The specific humidity during dehumidification process
A. Remains constant
B. Increases
C. Decreases
D. None of these
Answer : C

41. The pressure at the inlet of a refrigerant compressor is called
A. Suction pressure
B. Discharge pressure
C. Critical pressure
D. Back pressure
Answer : A

42. The wet bulb temperature during sensible heating of air
A. Remains constant
B. Increases
C. Decreases
D. None of these
Answer : B

43. Moisture in Freon refrigeration system causes
A. Ineffective refrigeration
B. High power consumption
C. Freezing automatic regulating valve
D. Corrosion of whole system
Answer : C

44. The condition of refrigerant after passing through the expansion or throttle valve, in a vapour compression system is
A. High pressure saturated liquid
B. Wet vapour
C. Very wet vapour
D. Dry vapour
Answer : C

45. The process of under-cooling is generally brought about by
A. Circulating more quantity of cooling water through the condenser
B. Using water colder than the main circulating water
C. Employing a heat exchanger
D. Any one of the above
Answer : D

46. Refrigeration in aeroplanes usually employs the following refrigerant
A. CO2
B. Freon-11
C. Freon-22
D. Air
Answer : D

47. Chaperon equation is applicable for registration at
A. Saturation point of vapour
B. Saturation point of liquid
C. Sublimation temperature
D. Triple point
Answer : A

48. In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is
A. Heated and dehumidified
B. Heated and humidified
C. Cooled and humidified
D. Cooled and dehumidified
Answer : B

49. 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?
A. 1.25
B. 0.8
C. 0.5
D. 0.25
Answer : D

50. Domestic refrigerator working on vapour compression cycle uses the following type of expansion device
A. Electrically operated throttling valve
B. Manually operated valve
C. Thermostatic valve
D. Capillary tube
Answer : D