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MCQOPTIONS
This section includes 368 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
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» B. lower than that using Lithium Bromide water | |
| 52. |
With reciprocating compressor in vapour compression refrigeration system, wetcompression is not desirable because |
| A. | liquid trapped up in the head of cylinder may damage the compressor valves |
| B. | COP of the cycle decreases |
| C. | volumetric efficiency of compressor decreases |
| D. | mass flow rate per ton of refrigerant increases |
| Answer» B. COP of the cycle decreases | |
| 53. |
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» B. 22.5 C | |
| 54. |
The Wet bulb depression is zero when Relative humidity equals |
| A. | 0 |
| B. | 0.5 |
| C. | 0.75 |
| D. | 1 |
| Answer» E. | |
| 55. |
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» D. none of the above | |
| 56. |
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» B. dry bulb | |
| 57. |
During compression in a vapour compression cycle the refrigerant is super heated |
| A. | work done is increased |
| B. | C.O.P is increased |
| C. | Work done is reduced |
| D. | Refrigerating effect is reduced |
| Answer» B. C.O.P is increased | |
| 58. |
Wet compression vapour compression refrigeration cycle means |
| A. | Vapour compression takes place in wet region |
| B. | Vapour compression in dry region, but evaporation in wet region |
| C. | vapour compression in wet region, but leaves in superheated region |
| D. | None of the above |
| Answer» B. Vapour compression in dry region, but evaporation in wet region | |
| 59. |
The oil separator is incorporated in vapour compression refrigeration system |
| A. | between evaporator and compressor |
| B. | between compressor and condenser |
| C. | between condenser and Throttle valve |
| D. | between throttle valve and evaporator |
| Answer» C. between condenser and Throttle valve | |
| 60. |
A refrigeration cycle is usually a |
| A. | open cycle |
| B. | closed cycle |
| C. | mixed cycle |
| D. | Hybrid cycle |
| Answer» C. mixed cycle | |
| 61. |
At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant%! |
| A. | decreases |
| B. | increases |
| C. | remains same |
| D. | depends on other factors |
| Answer» C. remains same | |
| 62. |
In a refrigeration cycle, the flow of refrigerant is controlled by%! |
| A. | Compressor |
| B. | Condenser |
| C. | Evaporator |
| D. | Expansion valve |
| Answer» E. | |
| 63. |
An evaporator is also known as%! |
| A. | Freezing coil |
| B. | Cooling coil |
| C. | Chilling coil |
| D. | All of these |
| Answer» E. | |
| 64. |
The optimum effective temperature for human comfort is%! |
| A. | Higher in winter than in summer |
| B. | Lower in winter than in summer |
| C. | Same in winter and summer |
| D. | Not dependent on season |
| Answer» C. Same in winter and summer | |
| 65. |
Which of the following refrigerant has the highest freezing point.%! |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | R-12 |
| Answer» C. Sulphur dioxide | |
| 66. |
The bypass factor, in case of sensible cooling of air, is given by (where td‚ÇÅ = Dry bulb temperature of air entering the cooling coil, td‚ÇÇ = Dry bulb temperature of air leaving the cooling coil, and td‚ÇÉ = Dry bulb temperature of the cooling coil)%! |
| A. | (td‚ÇÅ -td‚ÇÉ)/( td‚ÇÇ -td‚ÇÉ) |
| B. | (td‚ÇÇ -td‚ÇÉ)/( td‚ÇÅ -td‚ÇÉ) |
| C. | (td‚ÇÉ -td‚ÇÅ)/( td‚ÇÇ -td‚ÇÉ) |
| D. | (td‚ÇÉ -td‚ÇÇ)/( td‚ÇÅ -td‚ÇÉ) |
| Answer» C. (td‚Äö√á√â -td‚Äö√á√Ö)/( td‚Äö√á√á -td‚Äö√á√â) | |
| 67. |
The reciprocating refrigerant compressors are very suitable for%! |
| A. | Small displacements and low condensing pressures |
| B. | Large displacements and high condensing pressures |
| C. | Small displacements and high condensing pressures |
| D. | Large displacements and low condensing pressures |
| Answer» D. Large displacements and low condensing pressures | |
| 68. |
In a vapour compression system, the condition of refrigerant before entering the expansion or throttle valve is%! |
| A. | High pressure saturated liquid |
| B. | Wet vapour |
| C. | Very wet vapour |
| D. | Dry vapour |
| Answer» B. Wet vapour | |
| 69. |
The air cooling system mostly used in transport type aircrafts is%! |
| A. | Simple air cooling system |
| B. | Simple evaporative air cooling system |
| C. | Bootstrap air cooling system |
| D. | All of these |
| Answer» D. All of these | |
| 70. |
A mixture of dry air and water vapour, when the air has diffused the maximum amount of water vapour into it, is called%! |
| A. | Dry air |
| B. | Moist air |
| C. | Saturated air |
| D. | Specific humidity |
| Answer» D. Specific humidity | |
| 71. |
The boiling point of ammonia is%! |
| A. | -10.5°C |
| B. | -30°C |
| C. | -33.3°C |
| D. | -77.7°C |
| Answer» D. -77.7¬¨‚àûC | |
| 72. |
The dry bulb temperature during sensible heating of air%! |
| A. | Remains constant |
| B. | Increases |
| C. | Decreases |
| D. | None of these |
| Answer» C. Decreases | |
| 73. |
The advantage of dry compression is that%! |
| A. | It permits higher speeds to be used |
| B. | It permits complete evaporation in the evaporator |
| C. | It results in high volumetric and mechanical efficiency |
| D. | All of the above |
| Answer» E. | |
| 74. |
The capillary tube is not used in large capacity refrigeration systems because%! |
| A. | Cost is too high |
| B. | Capacity control is not possible |
| C. | It is made of copper |
| D. | Required pressure drop cannot be achieved |
| Answer» C. It is made of copper | |
| 75. |
A standard ice point temperature corresponds to the temperature of%! |
| A. | Water at 0°C |
| B. | Ice at 4°C |
| C. | Solid and dry ice |
| D. | Mixture of ice and water under equilibrium conditions |
| Answer» E. | |
| 76. |
In case of sensible cooling of air, the coil efficiency is given by%! |
| A. | B.P.F. - 1 |
| B. | 1 - B.P.F. |
| C. | 1/ B.P.F. |
| D. | 1 + B.P.F. |
| Answer» C. 1/ B.P.F. | |
| 77. |
The vapour pressure of refrigerant should be%! |
| A. | Lower than atmospheric pressure |
| B. | Higher than atmospheric pressure |
| C. | Equal to atmospheric pressure |
| D. | Could be anything |
| Answer» C. Equal to atmospheric pressure | |
| 78. |
*$_The reciprocating refrigerant compressors are very suitable for? |
| A. | Small displacements and low condensing pressures |
| B. | Large displacements and high condensing pressures |
| C. | Small displacements and high condensing pressures |
| D. | Large displacements and low condensing pressures |
| Answer» D. Large displacements and low condensing pressures | |
| 79. |
*$_The air cooling system mostly used in transport type aircrafts is? |
| A. | Simple air cooling system |
| B. | Simple evaporative air cooling system |
| C. | Bootstrap air cooling system |
| D. | All of these |
| Answer» D. All of these | |
| 80. |
*$_In a vapour compression system, the condition of refrigerant before entering the expansion or throttle valve is? |
| A. | High pressure saturated liquid |
| B. | Wet vapour |
| C. | Very wet vapour |
| D. | Dry vapour |
| Answer» B. Wet vapour | |
| 81. |
*$_The bypass factor, in case of sensible cooling of air, is given by (where td‚ÇÅ = Dry bulb temperature of air entering the cooling coil, td‚ÇÇ = Dry bulb temperature of air leaving the cooling coil, and td‚ÇÉ = Dry bulb temperature of the cooling coil)? |
| A. | (td‚ÇÅ -td‚ÇÉ)/( td‚ÇÇ -td‚ÇÉ) |
| B. | (td‚ÇÇ -td‚ÇÉ)/( td‚ÇÅ -td‚ÇÉ) |
| C. | (td‚ÇÉ -td‚ÇÅ)/( td‚ÇÇ -td‚ÇÉ) |
| D. | (td‚ÇÉ -td‚ÇÇ)/( td‚ÇÅ -td‚ÇÉ) |
| Answer» C. (td‚Äö√á√â -td‚Äö√á√Ö)/( td‚Äö√á√á -td‚Äö√á√â) | |
| 82. |
*$_In case of sensible cooling of air, the coil efficiency is given by? |
| A. | B.P.F. - 1 |
| B. | 1 - B.P.F. |
| C. | 1/ B.P.F. |
| D. | 1 + B.P.F. |
| Answer» C. 1/ B.P.F. | |
| 83. |
*$_A standard ice point temperature corresponds to the temperature of? |
| A. | Water at 0°C |
| B. | Ice at 4°C |
| C. | Solid and dry ice |
| D. | Mixture of ice and water under equilibrium conditions |
| Answer» E. | |
| 84. |
*$_The boiling point of ammonia is? |
| A. | -10.5°C |
| B. | -30°C |
| C. | -33.3°C |
| D. | -77.7°C |
| Answer» D. -77.7¬¨‚àûC | |
| 85. |
*$_The vapour pressure of refrigerant should be? |
| A. | Lower than atmospheric pressure |
| B. | Higher than atmospheric pressure |
| C. | Equal to atmospheric pressure |
| D. | Could be anything |
| Answer» C. Equal to atmospheric pressure | |
| 86. |
*$_The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases,? |
| A. | Will be higher |
| B. | Will be lower |
| C. | Will remain unaffected |
| D. | May be higher or lower depending upon the nature of non-condensable gases |
| Answer» B. Will be lower | |
| 87. |
*$_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» B. Decreases with increase in velocity of air passing through it | |
| 88. |
*$_Bell Coleman cycle is a? |
| A. | Reversed Carnot cycle |
| B. | Reversed Otto cycle |
| C. | Reversed Joule cycle |
| D. | Reversed Rankine cycle |
| Answer» D. Reversed Rankine cycle | |
| 89. |
*$_The refrigerant supplied to a compressor must be? |
| A. | Superheated vapour refrigerant |
| B. | Dry saturated liquid refrigerant |
| C. | A mixture of liquid and vapour refrigerant |
| D. | None of these |
| Answer» B. Dry saturated liquid refrigerant | |
| 90. |
*$_Absorption system normally uses the following refrigerant? |
| A. | Freon-11 |
| B. | Freon-22 |
| C. | CO2 |
| D. | Ammonia |
| Answer» E. | |
| 91. |
*$_The humidification process, on the psychrometric chart is shown by? |
| A. | Horizontal line |
| B. | Vertical line |
| C. | Inclined line |
| D. | Curved line |
| Answer» C. Inclined line | |
| 92. |
*$_The vertical and uniformly spaced lines on a psychrometric chart indicates? |
| A. | Dry bulb temperature |
| B. | Wet bulb temperature |
| C. | Dew point temperature |
| D. | Specific humidity |
| Answer» B. Wet bulb temperature | |
| 93. |
*$_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» C. Higher than | |
| 94. |
*$_Critical temperature is the temperature above which? |
| A. | A gas will never liquefy |
| B. | A gas will immediately liquefy |
| C. | Water will evaporate |
| D. | Water will never evaporate |
| Answer» B. A gas will immediately liquefy | |
| 95. |
*$_Relative humidity is given by (where pv = Partial pressure of water vapour, pb = Barometric pressure, ps = Pressure of saturated air, pd = Pressure at dry bulb temperature, pw = Saturation pressure corresponding to wet bulb temperature, and μ = Degree of saturation)? |
| A. | 0.622 Pv / (Pb - Pv) |
| B. | μ/[1 - (1 - μ) (Ps/Pb)] |
| C. | [Pv (Pb - Pd)]/ [Pd (Pb - Pv)] |
| D. | None of these |
| Answer» C. [Pv (Pb - Pd)]/ [Pd (Pb - Pv)] | |
| 96. |
*$_The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P.? |
| A. | More |
| B. | Less |
| C. | Equally |
| D. | Unpredictable |
| Answer» B. Less | |
| 97. |
*$_The atmospheric air at dry bulb temperature of 15°C enters a heating coil maintained at 40°C. The air leaves the heating coil at 25°C. The bypass factor of the heating coil is? |
| A. | 0.376 |
| B. | 0.4 |
| C. | 0.6 |
| D. | 0.67 |
| Answer» D. 0.67 | |
| 98. |
*$_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» D. None of these | |
| 99. |
*/*_The advantage of dry compression is that? |
| A. | It permits higher speeds to be used |
| B. | It permits complete evaporation in the evaporator |
| C. | It results in high volumetric and mechanical efficiency |
| D. | All of the above |
| Answer» E. | |
| 100. |
*/*_A mixture of dry air and water vapour, when the air has diffused the maximum amount of water vapour into it, is called? |
| A. | Dry air |
| B. | Moist air |
| C. | Saturated air |
| D. | Specific humidity |
| Answer» D. Specific humidity | |