McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
Chapters
| 51. |
In a flooded type of Evaporator which of the following types of expansion device is utilized |
| A. | Float Valve |
| B. | Thermostatic device |
| C. | Capillary tube |
| D. | Self actuated expansion valve |
| Answer» A. Float Valve | |
| 52. |
Which of the following statements are TRUE? |
| A. | A capillary tube is a variable opening area type expansion device |
| B. | In a capillary tube pressure drop takes place due to fluid friction |
| C. | In a capillary tube pressure drop takes place due to fluid acceleration |
| D. | In a capillary tube pressure drop takes place due to fluid friction and acceleration |
| Answer» 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 |
| A. | more |
| B. | less |
| C. | may be more or less |
| D. | un - predictable |
| Answer» B. less | |
| 54. |
The function of compressor in vapour compression refrigeration system is performed in vapour absorption system by |
| A. | generator |
| B. | absorber |
| C. | generator, absorber and liquid pump |
| D. | absorber and liquid pump |
| Answer» 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 |
| A. | 0.5 |
| B. | 0.35 |
| C. | 2 |
| D. | in sufficient data |
| Answer» B. 0.35 | |
| 56. |
Electrolux system of refrigeration has |
| A. | only one liquid pump |
| B. | only two liquid pumps |
| C. | no liquid pump |
| D. | none of the above |
| Answer» C. no liquid pump | |
| 57. |
Electrolux refrigerators has the following working substances |
| A. | Hydrogen |
| B. | Ammonia and Hydrogen |
| C. | Ammonia and water |
| D. | Ammonia, hydrogen and water |
| Answer» D. Ammonia, hydrogen and water | |
| 58. |
Which of the following system can be called as mechanical system of refrigeration |
| A. | Vapour absorption system |
| B. | Vapour compression system |
| C. | Steam jet refrigeration system |
| D. | None of the above |
| Answer» B. Vapour compression system | |
| 59. |
The vapour absorption refrigeration system using Ammonia – water has cycle operating pressures |
| A. | higher than that using Lithium Bromide – water |
| B. | lower than that using Lithium Bromide – water |
| C. | may be higher or lower depending upon application |
| D. | higher for sub-zero application and lower for above zero application |
| Answer» A. higher than that using Lithium Bromide – water | |
| 60. |
Shaft work required for vapour absorption system to produce 1 ton refrigeration may be only |
| A. | 50 to 60% of that required for vapour compression system |
| B. | 20 to 30% of that required for vapour compression system |
| C. | 1 to 2% of that required for vapour compression system |
| D. | none of the above |
| Answer» 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 |
| A. | les |
| B. | more |
| C. | may be more or less |
| D. | un - predictable |
| Answer» A. les | |
| 62. |
Munters Platen system of refrigeration is |
| A. | Vapour absorption system with ammonia and water |
| B. | Vapour compression system with ammonia as working substance |
| C. | Electrolux system with Hydrogen, ammonia and water as working substances |
| D. | none of the above |
| Answer» C. Electrolux system with Hydrogen, ammonia and water as working substances | |
| 63. |
Electrolux refrigerators is |
| A. | Vapour compression refrigerator with one compressor |
| B. | vapour absorption refrigerator with no pump |
| C. | vapour absorption refrigerator with one aqua pump |
| D. | None of the above |
| Answer» B. vapour absorption refrigerator with no pump | |
| 64. |
The Wet bulb depression is zero when Relative humidity equals |
| A. | 0 |
| B. | 0.5 |
| C. | 0.75 |
| D. | 1 |
| Answer» D. 1 | |
| 65. |
.In a psychrometric chart, the vertical lines parallel to the ordinate indicate |
| A. | Dry bulb Temperature |
| B. | Wet bulb Temperature |
| C. | Specific humidity |
| D. | Enthalpy of saturation |
| Answer» A. Dry bulb Temperature | |
| 66. |
Which of the following statements are TRUE? |
| A. | Thermodynamic WBT is a property of moist air, while WBT as measured by wet bulb thermometer is not a property |
| B. | Both the thermodynamic WBT and WBT as measured by wet bulb thermometer are properties of moist air |
| C. | Under no circumstances, dry bulb and wet bulb temperatures are equal |
| D. | Wet bulb temperature is always lower than dry bulb temperature, but higher than dew point temperature |
| Answer» 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? |
| A. | During cooling and humidification process, the enthalpy of air decreases |
| B. | During cooling and humidification process, the enthalpy of air increases |
| C. | During cooling and humidification process, the enthalpy of air remains constant |
| D. | During cooling and humidification process, the enthalpy of air may increase, decrease or remain constant depending upon the temperature of the wet surface |
| Answer» 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: |
| A. | 20 C |
| B. | 22.5 C |
| C. | 25 C |
| D. | Cannot be found |
| Answer» A. 20 C | |
| 69. |
The temperature at which the water vapour in the air starts. condensing is known as |
| A. | dew point |
| B. | dry bulb |
| C. | wet bulb |
| D. | saturation |
| Answer» A. dew point | |
| 70. |
When moisture is added to air at constant dry bulb temperature, the process is known as |
| A. | Sensible cooling |
| B. | humidification |
| C. | dehumidification |
| D. | Chilling |
| Answer» B. humidification | |
| 71. |
Which of the following can be measured by a sling psychrometer? |
| A. | Wet bulb temperature |
| B. | Dry bulb as well as wet bulb temperatures |
| C. | Specific humidity |
| D. | Absolute humidity |
| Answer» 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 |
| A. | Drier |
| B. | Solenoid valve |
| C. | Expansion valve |
| D. | The change is gradual throughout the cycle |
| E. | Evaporator |
| Answer» C. Expansion valve | |
| 73. |
The ratio of sensible heat to total heat is known as |
| A. | Relative humidity |
| B. | Humidification ratio |
| C. | Sensible heat factor |
| D. | Specific humidity |
| E. | Dew point |
| Answer» C. Sensible heat factor | |
| 74. |
The flow of the refrigerant in a refrigeration cycle is controlled by |
| A. | Copper tubing |
| B. | Compressor |
| C. | Expansion valve |
| D. | Evaporator |
| E. | Condenser |
| Answer» C. Expansion valve | |
| 75. |
The refrigerant used for the air-conditioning of passenger aircraft cabin is |
| A. | Air |
| B. | Carbondioxide |
| C. | Freon 11 |
| D. | Ammonia |
| E. | Freon 12 |
| Answer» B. Carbondioxide | |
| 76. |
Under increased atmospheric pressure (as compared to the standard conditions) the steam will condense at |
| A. | 100?C |
| B. | More than 100?C |
| C. | Depends on other conditions |
| D. | Less than 100?C |
| E. | Has nothing to do with pressure |
| Answer» B. More than 100?C | |
| 77. |
Which refrigerant has the highest critical point temperature? |
| A. | Ammonia |
| B. | Freon 11 |
| C. | Freon 12 |
| D. | Freon 22 |
| E. | None of the above |
| Answer» B. Freon 11 | |
| 78. |
The ratio of high temperature to low temperature for reversed Carnot refrigerator is 1.25. The COP will be |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| E. | All of the above |
| Answer» C. 4 | |
| 79. |
When the higher temperature is fixed, the COP of a refrigerating machine can be improved by |
| A. | Operating the machine at higher speeds |
| B. | Operating the machine at lower speeds |
| C. | Raising the higher temperature |
| D. | Lowering the higher temperature |
| E. | None of the above |
| Answer» 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 |
| A. | 1.5 |
| B. | 2 |
| C. | 1.25 |
| D. | 2.5 |
| E. | None of the above |
| Answer» 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 |
| A. | Baffle |
| B. | Bellows |
| C. | Regulator |
| D. | Diffuser |
| E. | None of the above |
| Answer» A. Baffle | |
| 82. |
The leaks of refrigerant from a cycle may be detected by |
| A. | Halide torch test |
| B. | Sulphur candle test |
| C. | Soap and water test |
| D. | Any of above |
| E. | None of the above |
| Answer» D. Any of above | |
| 83. |
Super-conductors |
| A. | Cannot be magnetised at low temperatures |
| B. | Can be rubbed with other superconductors without frictional effects at low temperatures |
| C. | Offer no resistance to flow of electricity at low remperatures |
| D. | Offer no resistance to flow of heat at low temperatures |
| E. | Offer no resistance to flow of fluids at low temperatures |
| Answer» C. Offer no resistance to flow of electricity at low remperatures | |
| 84. |
A desicant is |
| A. | A process of removing heat under controlled conditions |
| B. | A substance which reduces the viscosity of liquids |
| C. | A solid substance capable of removing moisture from a gas, liquid or solid |
| D. | Anammonia and a water solution |
| E. | Heat given off by cargo |
| Answer» 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 |
| A. | Dehumidifier |
| B. | Drier |
| C. | Solenoid |
| D. | Expansion valve |
| E. | Humidstat |
| Answer» B. Drier | |
| 86. |
The difference between wet and dry bulb temperatures |
| A. | Increases at atmospheric temperature |
| B. | Increases as air gets wet |
| C. | Increases as air gets drier |
| D. | remains constant always |
| E. | None of the above |
| Answer» C. Increases as air gets drier | |
| 87. |
In a vapour compression cycle the vapour as it leaves the compressor is |
| A. | In liquid form |
| B. | Wet vapour |
| C. | Dry vapour |
| D. | Dry and saturated vapour |
| E. | None of the above |
| Answer» D. Dry and saturated vapour | |
| 88. |
Refrigerant No. 717 is |
| A. | Ammonia |
| B. | Freon 12 |
| C. | Carbondioxide |
| D. | Freon 22 |
| E. | Methyl chloride |
| Answer» A. Ammonia | |
| 89. |
In a domestic refrigerator if the compressor runs continuously, it shows that |
| A. | The system is working perfectly all right |
| B. | The refrigeration is to full capacity |
| C. | The system is overloaded |
| D. | Any of the above |
| E. | None of the above |
| Answer» C. The system is overloaded | |
| 90. |
The ability of an evaporator to absorb heat does not depends on |
| A. | Temperature difference between the evaporator and the surrounding air |
| B. | Its size, surface condition and material |
| C. | Kind of refrigerant used |
| D. | Velocity of turbulence |
| E. | Compressor speed |
| Answer» C. Kind of refrigerant used | |
| 91. |
pH value of a brine solution is |
| A. | More than |
| B. | 14 |
| C. | 70 |
| D. | Less than 7 |
| E. | Could be any value |
| Answer» E. Could be any value | |
| 92. |
In case of freon as refrigerant the pipe lines should be of |
| A. | Copper |
| B. | Brass |
| C. | Seamless steel tubes |
| D. | Stainless steel tubes |
| E. | None of the above |
| Answer» 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 |
| A. | 1.8 kg |
| B. | 0.5 kg |
| C. | 12 kg |
| D. | 1 kg |
| E. | 0.2 kg |
| Answer» A. 1.8 kg | |
| 94. |
In control cooling water system, chromates, phosphates and silicates are added to water |
| A. | To remove odour |
| B. | To increase remove foreign particle |
| C. | To inhibit corrosion |
| D. | To prevent scale formation |
| E. | To prevent algae growth |
| Answer» C. To inhibit corrosion | |
| 95. |
In a psychrometric chart horizontal line indicate |
| A. | Percentage humidity |
| B. | Dew point temperature |
| C. | Wet bulb temperature |
| D. | Relative humidity |
| E. | Dry bulb temperature |
| Answer» B. Dew point temperature | |
| 96. |
In a mechanical refrigeration system the highest temperature of refrigerant occurs |
| A. | Between condenser and evaporator |
| B. | In evaporator |
| C. | Before expansion valve |
| D. | Between compressor and condenser |
| E. | Before expansion valve |
| Answer» D. Between compressor and condenser | |
| 97. |
Which of the following refrigerant has the freezing point? |
| A. | Ammonia |
| B. | Carbondioxide |
| C. | Freon 11 |
| D. | Freon 22 |
| E. | All of the above |
| Answer» D. Freon 22 | |
| 98. |
Dehumidification means |
| A. | Removing humidity from a space |
| B. | Reducing the quantity of water vapour in a space |
| C. | Reducing the moisture content of a substance |
| D. | Any of the above |
| E. | None of the above |
| Answer» C. Reducing the moisture content of a substance | |
| 99. |
In a refrigeration system a condenser |
| A. | Receives liquid refrigerant and supplies liquid refrigerant |
| B. | Receives vapour refrigerant and supplies vapour refrigerant |
| C. | Receives vapour refrigerant and supplies liquid refrigerant |
| D. | Receives liquid refrigerant and supplies liquid refrigerant |
| E. | None of the above |
| Answer» C. Receives vapour refrigerant and supplies liquid refrigerant | |
| 100. |
Dry ice is |
| A. | Free from water |
| B. | Free from dissolved air or gases |
| C. | Does not contain impurities |
| D. | Solidified form of carbondioxide |
| E. | None of the above |
| Answer» D. Solidified form of carbondioxide | |
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