Q.1

A refrigerant compressor is used to

  • raise the pressure of the refrigerant
  • raise the temperature of the refrigerant
  • circulate the refrigerant through the refrigerating system
  • all of the above
Q.2

In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the

  • expansion valve to the evaporator
  • evaporator to the thermostat
  • condenser to the expansion valve
  • condenser to the evaporator
Q.3

It is desired to condition the outside air fromrelative humidity andC dry bulb temperature torelative humidity andC dry bulb temperature (room condition). The practical arrangement will be

  • dehumidification
  • cooling and humidification
  • cooling and dehumidification
  • dehumidification and pure sensible cooling
Q.4

During heating and humidification, the final relative humidity of air

  • is higher than that of the entering air
  • is lower than that of the entering air
  • can be lower or higher than that of the entering air
  • none of the above
Q.5

The absolute humidity is the mass of water vapour present in 1 m3 of dry air.

  • Agree
  • Disagree
Q.6

During heating and dehumidification process, dry bulb temperature

  • remains constant
  • increases
  • decreases
Q.7

The fluids used in electrolux refrigerator are

  • water and hydrogen
  • ammonia and hydrogen
  • ammonia, water and hydrogen
  • none of these
Q.8

In a vapour absorption refrigeration system, the compressor of the vapour compression system is replaced by

  • liquid pump
  • generator
  • absorber and generator
  • absorber, generator and liquid pump
Q.9

The process of undercooling is generally brought about by

  • circulating more quantity of cooling water through the condenser
  • using water colder than the main circulating water
  • employing a heat exchanger
  • any one of the above
Q.10

The refrigerant used in small-tonnage commercial machines (hermetically sealed units) is

  • ammonia
  • carbon dioxide
  • sulphur dioxide
  • R-12
Q.11

The refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called

  • sub-cooling or under-cooling
  • super-cooling
  • normal cooling
  • none of these
Q.12

A refrigerant compressor is used to

  • raise the pressure of the refrigerant
  • raise the temperature of the refrigerant
  • circulate the refrigerant through the refrigerating system
  • all of the above
Q.13

In a lithium bromide absorption refrigeration system

  • lithium bromide is used as a refrigerant and water as an absorbent
  • water is used as a refrigerant and lithium bromide as an absorbent
  • ammonia is used as a refrigerant and lithium bromide as an absorbent
  • none of the above
Q.14

In which of the following refrigeration system, waste heat can be effectively used?

  • Vapour compression cycle
  • Vapour absorption cycle
  • Air refrigeration cycle
  • none of these
Q.15

R-has the __________ freezing point.

  • lowest
  • highest
Q.16

Planck's law holds good for all coloured bodies.

  • True
  • False
Q.17

A Bell Coleman refrigerator working on dense air system as compared to open air system, for the same range of temperature, results in higher coefficient of performance.

  • Agree
  • Disagree
Q.18

In a reversed Brayton cycle, the heat is absorbed by the air during

  • isentropic compression process
  • constant pressure cooling process
  • isentropic expansion process
  • constant pressure expansion process
Q.19

In mechanical refrigeration system, the refrigerant has the maximum temperature

  • in evaporator
  • before expansion valve
  • between compressor and condenser
  • between condenser and evaporator
Q.20

The product of Reynolds number and Prandtl number is known as

  • Stanton number
  • Biot number
  • Peclet number
  • Grashoff number
Q.21

The central air conditioning system has __________ overall efficiency as compared to individual systems.

  • same
  • lower
  • higher
Q.22

The ratio of surface convection resistance to the internal conduction resistance is known as

  • Grashoff number
  • Biot number
  • Stanton number
  • Prandtl number
Q.23

Wet bulb temperature is the temperature of air recorded by a thermometer, when

  • it is not effected by the moisture present in the air
  • its bulb is surrounded by a wet cloth exposed to the air
  • the moisture present in it begins to condense
  • none of the above
Q.24

The capacity of a domestic refrigerator is in the range of

  • 0.1 to 0.3 TR
  • 1 to 3 TR
  • 3 to 5 TR
  • 5 to 7 TR
Q.25

The critical thickness of insulation for a sphere is

  • k/h0
  • 2k/h0
  • h0/k
  • h0/2k
Q.26

Carbon dioxide is

  • colourless
  • odourless
  • non-flammable
  • all of these
Q.27

The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. This statement is known as

  • Wien's law
  • Stefan's law
  • Kirchhoff's law
  • Planck's law
Q.28

The critical thickness of insulation for a sphere is

  • k/h0
  • 2k/h0
  • h0/k
  • h0/2k
Q.29

A device used for transfering heat from one fluid to another is called heat exchanger.

  • True
  • False
Q.30

The condition of refrigerant after passing through the condenser in a vapour compression system is

  • saturated liquid
  • wet vapour
  • dry saturated vapour
  • superheated vapour
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