Q.1

The temperature of air recorded by a thermometer, when its bulb is surrounded by a wet cloth exposed to the air, is called

  • wet bulb temperature
  • dry bulb temperature
  • dew point temperature
  • none of these
Q.2

In a pressure enthalpy chart, the space between the saturated liquid line and saturated vapour line, represents sub-cooled liquid region.

  • True
  • False
Q.3

The boiling point of carbon dioxide is

  • -20.5°C
  • -50°C
  • -63.3°C
  • -78.3°C
Q.4

A valve which maintains a constant degree of superheat at the end of the evaporator coil, is called

  • automatic expansion valve
  • high side float valve
  • thermostatic expansion valve
  • low side float valve
Q.5

The evaporator changes the low pressure liquid refrigerant from the expansion valve into

  • high pressure liquid refrigerant
  • low pressure liquid and vapour refrigerant
  • low pressure vapour refrigerant
  • none of these
Q.6

The ratio of actual heat transfer to the maximum possible heat transfer is known as heat exchanger effectiveness.

  • Agree
  • Disagree
Q.7

Most thermostatic expansion valves are set for a superheat of

  • 5°C
  • 10°C
  • 15°C
  • 20°C
Q.8

During sub-cooling, sensible heat from a liquid refrigerant is removed.

  • Yes
  • No
Q.9

R-has the highest critical point temperature.

  • Correct
  • Incorrect
Q.10

The mass of water vapour present in __________ is called absolute humidity.

  • 1 m3 of wetair
  • 1 m3 of dry air
  • 1 kg of wet air
  • 1 kg of dry air
Q.11

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 by-pass factor of the heating coil is

  • 0.376
  • 0.4
  • 0.6
  • 0.67
Q.12

Prandtl number (PN) is given by PN = μ.cp/k.

  • Yes
  • No
Q.13

For air conditioning the operation theatre in a hospital, the percentage of outside air in the air supplied is

  • zero
  • 20
  • 50
  • 100
Q.14

For large tonnage (more thanTR) air-conditioning applications, the compressor recommended is

  • reciprocating
  • rotating
  • centrifugal
  • screw
Q.15

If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called

  • absorptive power
  • emissive power
  • emissivity
  • none of these
Q.16

The ratio of heat extracted in the refrigerator to the workdone on the refrigerant is called

  • coefficient of performance of refrigeration
  • coefficient of performance of heat pump
  • relative coefficient of performance
  • refrigerating efficiency
Q.17

In a vapour compression system, the condition of refrigerant before passing through the condenser is

  • saturated liquid
  • wet vapour
  • dry saturated vapour
  • superheated vapour
Q.18

If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called

  • absorptive power
  • emissive power
  • emissivity
  • none of these
Q.19

The relative coefficient of performance is equal to

  • Actual C.O.P. x Theoretical C.O.P.
  • none of these
Q.20

An infinite parallel planes with emissivities e1 and e2, the interchange factor for radiation from surface 1 to surface 2 is given by

  • e1 + e2
  • e1e2
Q.21

In case ofsensible cooling of air, the coil efficiency is given by

  • B.P.F. - 1
    432-352-1.png
  • 1 - B.P.F.
    432-352-1.png
  • 1 + B.P.F.
Q.22

During adiabatic saturation process on unsaturated air __________ remains constant.

  • relative humidity
  • dew point temperature
  • dry bulb temperature
  • wet bulb temperature
Q.23

The humidity ratio or specific humidity is the mass of water vapour present in

  • 1 m3 of wet air
  • 1 m3 of dry air
  • 1 kg of wet air
  • 1 kg of dry air
Q.24

During a refrigeration cycle, heat is rejected by the refrigerant in a

  • compressor
  • condenser
  • evaporator
  • expansion valve
Q.25

While designing the refrigeration system of an aircraft, the prime consideration is that the

  • system has high C.O.P.
  • power per TR is low
  • mass of refrigerant circulated in the system is low
  • mass of the refrigeration equipment is low
Q.26

The critical radius is the insulation radius at which the resistance to heat flow is

  • maximum
  • minimum
  • zero
  • none of these
Q.27

The thickness of thermal and hydrodynamic boundary layer is equal if Prandtl number is

  • equal to one
  • greater than one
  • less than one
  • equal to Nusselt number
Q.28

The formation of frost on cooling coils in a refrigerator

  • increases heat transfer
  • improves C.O.P. of the system
  • increases power consumption
  • reduces power consumption
Q.29

A refrigeration system

  • removes heat from a low temperature body and delivers it to a high temperature body
  • removes heat from a high temperature body and delivers it to a low temperature body
  • rejects energy to a low temperature body
  • none of the above
Q.30

The heat transfer takes place according to

  • Zeroth law of thermodynamics
  • First law of thermodynamics
  • Second law of thermodynamics
  • Kirchhoff's law
0 h : 0 m : 1 s