Correct : B. two isentropic processes and two isothermal processes
2. Two Carnot Refrigerators are employed, one for ice making and other for comfort cooling
Correct : C. The COP of the refrigerator for ice making is lower than that for other
3. A reversed Carnot cycle has a COP of 4. The ratio of higher temperature to lower temperature will be
Correct : A. 1.25
4. Carnot refrigerator absorbs heat at -13° C and requires 1 kW for each 6.5 kW of heat absorbed, the COP and temperature of heat rejections respectively
Correct : A. COP = 6.5, t = 27° C
5. The dense air refrigeration system as compared to open air refrigeration system for same range of temperatures using Bell- Colemann cycle requires.
Correct : B. Lower power/Ton of Refrigeration
6. For very high speed planes cruising at Mach number 2.5 and above, the air craft refrigeration system recommended is
Correct : D. Boot strap evaporative type
7. The air craft system giving Lowest Dry Air Rated Turbine discharge temperature at supersonic cruising speeds of the plane, is
Correct : D. Boot strap evaporative system of Refrigeration
8. There are two cooling turbines in
Correct : A. Reduced ambient system of Refrigeration
9. There are two stages of compression of air in
Correct : B. Boot-strap system of Refrigeration
10. The amount of heat absorbed by the system at low temperature is
Correct : B. Refrigerating effect
11. No refrigerator using reversed Carnot cycle has been constructed because
Correct : D. isentropic portions of cycle require high speeds where as isothermal portions require low speeds
12. A refrigeration cycle is usually a
Correct : B. closed cycle
13. Co-efficient of performance of a Reversed Carnot cycle refrigerator working between
higher temperature T2 and lower temperature T1
Correct : A. will increase with increase in T1 keeping T2 fixed
14. Bell-Colemann cycle comprises
Correct : C. two isentropic processes and two isobaric processes
15. The COP of Carnot Refrigerator is 3 and it produces 1 TR. The work that will be done is equal to
Correct : A. 70 kJ/min
16. In Bell – Colemann refrigerator for the same temperature range
Correct : C. COP of dense air system is higher than COP of open air system
17. The air craft system giving Lowest Dry Air Rated Turbine discharge temperature at
supersonic cruising speeds of the plane, is
Correct : D. Boot strap evaporative system of Refrigeration
18. A Bell-Colemann cycle is
Correct : B. reversed Joule Cycle
19. In a refrigeration cycle the heat is rejected by refrigerant at
Correct : C. condenser
20. A reversible refrigerator working between two fixed temperatures
Correct : A. has the same COP whatever the working substance
21. A reversible refrigerator working between two fixed temperatures
Correct : A. has the same COP whatever the working substance
22. Heat is absorbed by the refrigerant, during vapour compression refrigeration cycle in
Correct : C. Evaporator
23. In a simple saturated vapour compression cycle, the refrigerant is in superheated condition
Correct : B. before entering condenser
24. Sub-cooling is a process of cooling the refrigerant in vapour compression refrigeration system
Correct : C. before Throttling
25. The order in which main components of vapour compression refrigeration system are used is
Correct : D. compressor-condenser- throttle valve- evaporator
26. The oil separator is incorporated in vapour compression refrigeration system
Correct : B. between compressor and condenser
27. In vapour compression refrigeration cycle the following data is available Heat rejected in condenser = 65 KW Work done in compressor = 10 kw, then COP( refrigerator) is
Correct : B. 5.5
28. Following results are tabulated for vapour compression refrigeration cycle.
Enthalpy at suction = 190 kJ/kg
Enthalpy at discharge from compressor = 210 kJ/kg
Enthalpy at exit from condenser = 80 kJ/kg
COP of cycle would be
Correct : C. 5.5
29. For simple saturated vapour compression refrigeration cycle operating between 5°C and 40°C, and the refrigerants being R-11, R-12, R-717 and R-22, the evaporator pressure is lowest for
Correct : A. R-11
30. For simple saturated vapour compression refrigeration cycle operating between 5°C and 40°C, and the refrigerants being R-11, R-12, R-717 and R-22, the compressor displacement per min per ton of refrigeration is highest for
Correct : A. R-11
31. With reciprocating compressor in vapour compression refrigeration system, wetcompression is not desirable because
Correct : A. liquid trapped up in the head of cylinder may damage the compressor valves
32. An ideal refrigerant should have
Correct : B. high critical temperature
33. The refrigerant leaving throttle valve is
Correct : D. fraction as saturated vapour and remainder as liquid
34. Freon group of refrigerants
Correct : C. non-toxic and non-inflammable
35. The leaks of refrigerant from a cycle may be detected by
Correct : D. any of the above
36. During compression in a vapour compression cycle the refrigerant is super heated
Correct : A. work done is increased
37. Heat is rejected by the refrigerant, during vapour compression refrigeration cycle in
Correct : B. Condenser
38. Wet compression vapour compression refrigeration cycle means
Correct : A. Vapour compression takes place in wet region
39. For simple saturated vapour compression refrigeration cycle operating between 5°C and 40°C, and the refrigerants being R-11, R-12, R-717 and R-22, the evaporator pressure is highest for
Correct : D. R-22
40. With reciprocating compressor in vapour compression refrigeration system, wet compression is not desirable because
Correct : A. liquid trapped up in the head of cylinder may damage the compressor valves
41. An ideal refrigerant should have
Correct : C. lower boiling point
42. During compression in a vapour compression cycle the refrigerant is super heated
Correct : A. C.O.P is reduced
43. Heat is absorbed by a refrigerant, during a refrigeration cycle in a
Correct : B. evaporator
44. What is the effect of frost on the cooling coils of the evaporator of refrigeration system
Correct : D. It acts as the insulator and decreases the heat transfer rate
45. The widely used refrigerant in domestic refrigerators is
Correct : C. Freon-12
46. Freon group refrigerants are
Correct : D. non- toxic & non-inflammable
47. Latent heat of vaporization of a refrigerant ,at lower temperatures and pressures
Correct : A. increase
48. The refrigerant with highest critical pressure is
Correct : B. Ammonia
49. The Refrigerant commonly used in commercial ice plants is
Correct : C. Ammonia
50. Which of the following refrigerants has the lowest boiling point?
Correct : B. Carbon-dioxide
51. In a flooded type of Evaporator which of the following types of expansion device is utilized
Correct : A. Float Valve
52. Which of the following statements are TRUE?
Correct : D. In a capillary tube pressure drop takes place due to fluid friction and acceleration
53. Co-efficient of performance of vapour absorption refrigeration system as compared to that for vapour compression refrigeration system is
Correct : B. less
54. The function of compressor in vapour compression refrigeration system is performed in vapour absorption system by
Correct : C. generator, absorber and liquid pump
55. In vapour absorption refrigeration system heating in generator is done at 100°C, refrigeration in evaporator at 10°C and cooling by cooling water in condenser at 30°C. The (COP)max is
Correct : B. 0.35
56. Electrolux system of refrigeration has
Correct : C. no liquid pump
57. Electrolux refrigerators has the following working substances
Correct : D. Ammonia, hydrogen and water
58. Which of the following system can be called as mechanical system of refrigeration
Correct : B. Vapour compression system
59. The vapour absorption refrigeration system using Ammonia – water has cycle operating pressures
Correct : A. higher than that using Lithium Bromide – water
60. Shaft work required for vapour absorption system to produce 1 ton refrigeration may be only
Correct : C. 1 to 2% of that required for vapour compression system
61. Work of compression of the fluid in vapour absorption refrigeration system as compared to that for vapour compression refrigeration system is
Correct : A. les
62. Munters Platen system of refrigeration is
Correct : C. Electrolux system with Hydrogen, ammonia and water as working substances
63. Electrolux refrigerators is
Correct : B. vapour absorption refrigerator with no pump
64. The Wet bulb depression is zero when Relative humidity equals
Correct : D. 1
65. .In a psychrometric chart, the vertical lines parallel to the ordinate indicate
Correct : A. Dry bulb Temperature
66. Which of the following statements are TRUE?
Correct : A. Thermodynamic WBT is a property of moist air, while WBT as measured by wet bulb thermometer is not a property
67. Which of the following statements are TRUE?
Correct : D. During cooling and humidification process, the enthalpy of air may increase, decrease or remain constant depending upon the temperature of the wet surface
68. An air stream at a flow rate of 1 kg/s and a DBT of 30 C mixes adiabatically with another air stream flowing with a mass flow rate of 2 kg/s and at a DBT of 15 C. Assuming no condensation to take place, the temperature of the mixture is approximately equal to:
Correct : A. 20 C
69. The temperature at which the water vapour in the air starts. condensing is known as
Correct : A. dew point
70. When moisture is added to air at constant dry bulb temperature, the process is known as
Correct : B. humidification
71. Which of the following can be measured by a sling psychrometer?
Correct : B. Dry bulb as well as wet bulb temperatures
72. In which part of the vapour compression cycle there is abrupt change in pressure and temperature
Correct : C. Expansion valve
73. The ratio of sensible heat to total heat is known as
Correct : C. Sensible heat factor
74. The flow of the refrigerant in a refrigeration cycle is controlled by
Correct : C. Expansion valve
75. The refrigerant used for the air-conditioning of passenger aircraft cabin is
Correct : B. Carbondioxide
76. Under increased atmospheric pressure (as compared to the standard conditions) the steam will condense at
Correct : B. More than 100?C
77. Which refrigerant has the highest critical point temperature?
Correct : B. Freon 11
78. The ratio of high temperature to low temperature for reversed Carnot refrigerator is 1.25. The COP will be
Correct : C. 4
79. When the higher temperature is fixed, the COP of a refrigerating machine can be improved by
Correct : C. Raising the higher temperature
80. A reversed Carnot cycle has a COP of 4. The ratio of higher temperature to lower temperature will be
Correct : C. 1.25
81. A plate of vane used to direct or control movement of fluid or air within the confined area is known as
Correct : A. Baffle
82. The leaks of refrigerant from a cycle may be detected by
Correct : D. Any of above
83. Super-conductors
Correct : C. Offer no resistance to flow of electricity at low remperatures
84. A desicant is
Correct : C. A solid substance capable of removing moisture from a gas, liquid or solid
85. A device designed to remove moisture from a refrigerant is called
Correct : B. Drier
86. The difference between wet and dry bulb temperatures
Correct : C. Increases as air gets drier
87. In a vapour compression cycle the vapour as it leaves the compressor is
Correct : D. Dry and saturated vapour
88. Refrigerant No. 717 is
Correct : A. Ammonia
89. In a domestic refrigerator if the compressor runs continuously, it shows that
Correct : C. The system is overloaded
90. The ability of an evaporator to absorb heat does not depends on
Correct : C. Kind of refrigerant used
91. pH value of a brine solution is
Correct : E. Could be any value
92. In case of freon as refrigerant the pipe lines should be of
Correct : C. Seamless steel tubes
93. When Freon 12 is used as a refrigerant in vapour compression cycle, the mass circulated per ton of refrigerating effect will be nearly
Correct : A. 1.8 kg
94. In control cooling water system, chromates, phosphates and silicates are added to water
Correct : C. To inhibit corrosion
95. In a psychrometric chart horizontal line indicate
Correct : B. Dew point temperature
96. In a mechanical refrigeration system the highest temperature of refrigerant occurs
Correct : D. Between compressor and condenser
97. Which of the following refrigerant has the freezing point?
Correct : D. Freon 22
98. Dehumidification means
Correct : C. Reducing the moisture content of a substance
99. In a refrigeration system a condenser
Correct : C. Receives vapour refrigerant and supplies liquid refrigerant