1. A refrigerating machine working on Reversed Carnot cycle takes out 2 kW per minute of heat from the system while working between temperature limits of 300?K and 200?K. The C.O.P. and power consumed by the cycle will be
Correct : A. 2. 1 kW
2. In halide torch test if there is leakage of refrigerant, the colour of flame with change to
Correct : C. Blue or bright green
3. If the discharge pressure of a refrigeration compressor is too high it shows
Correct : B. Lack of refrigerant
4. Oil separator in a refrigeration cycle is installed
Correct : D. Between compressor and condenser
5. If a refrigerator compressor cuts out on starter overloads the probable reason could be
Correct : E. Any of the above
6. In electrolus refrigerator
Correct : B. Ammonia evaporates in hydrogen
7. A condenser removes from the refrigerant
Correct : A. Sensible heat only
8. During dehumidification process
Correct : A. Relative humidity decreases
9. In a refrigerator evaporator is located
Correct : A. Inside the refrigerator cabinet
10. In case of wet bulb depression is zero, it can be concluded that
Correct : D. Relative humidity is 100%
11. Freon type (halocarbons) refrigerants are
Correct : E. Non-poisonous
12. Brine is always used as a secondary refrigerant in
Correct : D. Ice plant
13. The bulk of tubes at the back of the domestic refrigerator are
Correct : A. Condenser tubes
14. Out of the following refrigerants which one will provide highest compressor displacement per tonne of refrigeration in a vapour compression system operating between fixed temperatures
Correct : C. Freon 11
15. Which of the following has lowest COP?
Correct : C. Vapour absorption cycle
16. The performance of an evaporative condenser largely depends on
Correct : A. Wet bulb temperature
17. The rate of evaporation of water will be low when
Correct : C. Relative humidity is high
18. Dry bulb temperature depends on
Correct : E. None of the above
19. In a psychrometric chart vertical lines indicate
Correct : B. Dry bulb temperature
20. In case of completely dry air
Correct : B. Total heat is same as sensible heat
21. When the lower temperature is fixed, the COP of a refrigerating machine can be improved by
Correct : D. None of the above
22. Water is used as a refrigerant in
Correct : B. Steam jet refrigeration
23. During adiabatic saturation process on unsaturated air
Correct : B. Wet bulb temperature remains constant
24. In a vapour compression refrigeration cycle, high head pressure is indicated which does not change even when compressor is stopped and allowed to cool. The probable cause may be
Correct : C. Air in the system
25. A critical temperature is the temperature
Correct : B. Above which a gas will never be liquefied
26. A Salinometer
Correct : E. Measures density of brine
27. In cooling towers the heat is dissipated mainly by
Correct : E. Evaporation
28. Capacity of a domestic refrigerator is in the range
Correct : C. 0.1 to 0.3 tonnes
29. If a refrigerator is directly exposed to sun rays
Correct : C. There will be less cooling effect
30. A refrigerating system operates on the reversed Carnot cycle. The higher temperature of the refrigerant in the system is 40?C and the lower is - 15?C. The capacity is to be 10 tons. Neglecting all losses, the coefficient of performance of the system would be
Correct : D. 4.69
31. As warm air cools, its
Correct : B. Relative humidity decreases
32. In a small vapour compression cycle using capillary tubing for expansion, if suddenly uncondensed vapours enter the tubing, the result will be
Correct : B. Loss in refrigerating capacity
33. In which section of a vapour compression system, the refrigerant is generally in the form of a wet vapour?
Correct : C. Evaporator
34. In a vapour absorption system as compared to vapour compression system, the compressor is replaced by
Correct : E. Absorber and generator
35. In a refrigerating system work done per kg of air is 20 kcal and heat extracted per kg of air is 25 kcal. The quantity of refrigerant used is 10 kg. The coefficient of performance of the system would be
Correct : E. 1.25
36. If a one ton refrigeration machine, the significance of term "One ton" is that
Correct : B. One ton of ice when melts from and at 0?C in 24 hours the refrigeration effect equivalent to that
37. The change in temperature resulting from a gas expanding from one constant pressure, with no heat transfer and no external work other than to maintain the constant pressure is known as
Correct : D. Joule - Thomoson effect
38. Anhydrous substance is
Correct : E. Free of water especially water of crystallization
39. No refrigerator using reversed Carnot cycle has been constructed because
Correct : A. It is uneconomical
40. The statement: If a maximum of gases or vapours is enclosed in a container, each will exert its own pressure on the container entirely independent of the others and the total absolute pressure will be equal to the sum of the partial pressure exerted by each of the gases. This statement is known as
Correct : E. Dalton's law of partial pressures.
41. Defrosting of evaporators is done because
Correct : B. Frosting retards heat flow
42. No liquid can exist as a liquid at
Correct : B. Zero pressure
43. Dischloromono fluoroethane is
Correct : D. Freon 22
44. In a refrigeration system, if the compressor short cycles, the probable cause could be
Correct : E. Any of the above
45. Reversed Carnot cycle assumes that all processes in the cycle are
Correct : D. Non flow or steady flow
46. Which of the following valves is used on domestic refrigerators
Correct : E. None of the above
47. A thermometer installed, in a vapour compression ammonia system, after the condenser shows elevated reading than the normal. It shows that
Correct : D. Any of the above
48. One a psychrometric chart cooling and humidification process using spray can be shown by
Correct : A. A line parallel to wet bulb temperature lines
49. In a vapour compression cycle the refrigerant immediately after expansion valve is in
Correct : B. Wet vapour form
50. If wet bulb temperature is same as dew point, the relative humidity of air will be
Correct : D. 100
51. 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
Correct : C. 4000 litres through 300 ton plant and 2400 litres through 500 ton plant
52. Which of the following refrigerant has the lowest specific volume?
Correct : E. Carbondioxide
53. Which of the following refrigerant compressor is not classified as positive displacement compressor
Correct : B. Centrifugal compressor
54. Class II group of refrigerants absorb sensible heat while giving refrigeration effect. Which of the following is a class II refrigerant
Correct : D. Methyl chloride
55. The critical pressure of a liquid is the pressure
Correct : B. Above which a liquid will remain a liquid
56. Frost on cooling coils
Correct : D. Acts as an insulation, increasing power consumption
57. The coefficient of performance of a domestic refrigerator as compared to that of an air conditioner is gererally
Correct : A. Less
58. The leakage in a refrigeration system using freon is detected by
Correct : B. Halide torch
59. The critical temperature for Freon 12 is
Correct : A. Above 100?C
60. In a vapour compression cycle the lowest temperature occurs in
Correct : A. Evaporator
61. If dry bulb temperature is 25?C and wet bulb temperature is 18?C, then which of the following temperatures could possibly represent dew point?
Correct : A. 14?C
62. The effect of under cooling the refrigerant is to
Correct : B. Increase the COP of the cycle
63. Clear ice
Correct : D. Is produced by blowing air during freezing
64. Two thermometers are constructed in the same way except that one has a spherical bulb and the other an elongated cylindrical bulb. Which one will respond quickly to temperature change?
Correct : B. Cylindrical bulb thermometer
65. A low wet bulb temperature indicates
Correct : D. (A) and (B) above
66. On a psychrometric chart sensible heating or cooling is represented by
Correct : A. A horizontal line
67. During sensible heating of air
Correct : D. Both dry bulb temperature as well as enthalpy increase
68. Air and other non-condensable gases (foul gases) get into a refrigeration system through
Correct : E. Any of the above
69. Refrigerant 717 is
Correct : E. Ammonia
70. The relation between vapour pressure to the enthalpy of vaporisation is expressed in
Correct : D. Clausius Clapeyron equation
71. For a sensible heating the air is passed over a heating coil which may be
Correct : E. Heated by any of the above methods
72. Cryogenics
Correct : D. Is the field of engineering associated with development, production and use of equipment in the range -180?C to absolute zero
73. Dew point is
Correct : E. The temperature at which condensation of water vapour in air starts
74. A refrigerant with lowest freezing point temperature is
Correct : C. Freon 22
75. A storage tank which receives liquid refrigerant from evaporator and prevents it from flowing into suction line is known as
Correct : A. Accumulator
76. In a vapour compression refrigeration cycle using ammonia as a refrigerant the temperature of ammonia after compression will be at the range
Correct : B. 70?C to - 110?C
77. The condition of refrigerant before and after compression in vapour compression cycle is
Correct : D. Wet vapour, cry saturated vapour
78. The ratio of water vapour to the mass of dry air in a given mixture is known as
Correct : A. Humidity ratio
79. When air is adiabatically saturated, the temperature attained is known as
Correct : D. Wet bulb temp
80. In case air is cooled by a process in which the humidity ratio of air does not change, the process is known as
Correct : D. Sensible cooling
81. If the compressor of a refrigeration system is noisy, it shows that
Correct : E. Any of the above
82. Which of the following refrigerant is highly toxic?
Correct : E. Sulphurdioxide
83. For for measurement of temperature in cryogenic range the thermometers used are
Correct : A. Gas thermometers
84. The freezing point of ammonia is
Correct : C. ? 77.8?C
85. Presence of moisture in a refrigeration cycle will show its effect at
Correct : C. Expansion valve
86. The colour of the flame of halide torch in case of leakage of freon refrigerant, will change to
Correct : C. Green
87. One tonne of refrigeration is equivalent to SI units of
Correct : A. 3.5 kW
88. In vapour compression cycle the highest temperature of the refrigerant during the cycle occurs
Correct : D. After compression
89. Sub-cooling is
Correct : D. Cooling a part of liquid
90. Which of the following refrigerant is the cheapest?
Correct : A. Air
91. Which of the following is not a property of Carbondioxide?
Correct : D. Pungent odour
92. If a room has bad ammonia leaks
Correct : D. Gas mask should be put on
93. The moisture in a refrigeration system is removed by
Correct : A. Driers
94. When ammonia is used as a refrigerant in vapour compression cycle, the mass circulated per ton of refrigerating effect will be nearly
Correct : A. 0.2 kg
95. Which type of compressor is commonly used in room air-conditioner
Correct : A. Reciprocating
96. If the condensation temperature of a refrigerant is 25?C which type of condenser cannot be used?
Correct : A. Air cooled condenser
97. During air conditioning whenever two or more streams of moist air are mixed they follow
Correct : E. Adiabatic process
98. Air for air conditioning of aircraft cabin is obtained by
Correct : C. Bleeding from air compressor
99. Which of the following connections is usually not provided in a hermetically sealed type compressors?
Correct : D. Lubricating oil charging connection
100. In ammonia vapour compression system the temperature rise between the condenser outlet and the expansion valve should be
Correct : C. As little as possible for better performance