Q.1

Thermal conductivity of air increases with rise in temperature.

  • Correct
  • Incorrect
Q.2

The transfer of heat from one body to another takes place only when there is a temperature difference between the bodies.

  • Yes
  • No
Q.3

The curved lines on a psychrometric chart indicates

  • dry bulb temperature
  • wet bulb temperature
  • dew point temperature
  • relative humidity
Q.4

The centrifugal compressors are generally used for refrigerants that require

  • small displacements and low condensing pressures
  • large displacements and high condensing pressures
  • small displacements and high condensing pressures
  • large displacements and low condensing pressures
Q.5

The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number)n, where n is equal to

  • -1/3
  • -2/3
  • 1
  • -1
Q.6

The critical pressure of a liquid is the pressure

  • above which a liquid will remain a liquid
  • above which a liquid will explode
  • above which a liquid will always convert into a vapour
  • below which a liquid will always be in vapour form
Q.7

The specific humidity during dehumidification process

  • remains constant
  • increases
  • decreases
Q.8

The process, generally used in winter air-conditioning to warm and humidity the air, is called

  • humidification.
  • dehumidification
  • heating and humidification
  • cooling and dehumidification
Q.9

During gas charging in an ammonia vapour compression system, the connection is made at the compressor outlet.

  • Agree
  • Disagree
Q.10

In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in

  • parallel flow
  • counter flow
  • cross flow
  • all of these
Q.11

The material of pipe lines for a system using ammonia as a refrigerant should be copper.

  • Yes
  • No
Q.12

During humidification process, __________ increases.

  • wet bulb temperature
  • relative humidity
  • dry bulb temperature
  • specific humidity
Q.13

The water, alcohol and ammonia have same refrigerating effect at different altitudes.

  • Yes
  • No
Q.14

Conduction is a process of heat transfer

  • from one particle of the body to another without the actual motion of the particles
  • from one particle of the body to another by the actual motion of the heated particles.
  • from a hot body to a cold body, in a straight line, without affecting the intervening medium
  • none of the above
Q.15

Which of the following refrigerant has the lowest freezing point?

  • R-11
  • R-12
  • R-22
  • Ammonia
Q.16

Atrelative humidity, wet bulb temperature, dry bulb temperature, dew point temperature and saturation temperature are equal.

  • Correct
  • Incorrect
Q.17

Which of the following statement is correct?

  • A grey body is one which absorbs all radiations incident on it.
  • At thermal equilibrium, the emissivity and absorptivity are same.
  • The energy absorbed by a body to the total energy falling on it, is called emissivity.
  • A perfect body is one which is black in colour.
Q.18

The wave length corresponding to the maximum energy is inversely proportional to the absolute temperature. This statement is called Planck's law.

  • Yes
  • No
Q.19

A pressure gauge on the discharge side of a refrigerant compressor reads too high. The reasons will be

  • lack of cooling water
  • water temperature being high
  • dirty condenser surface
  • all of these
Q.20

The automobile radiator is a heat exchanger of

  • parallel flow type
  • counter flow type
  • cross flow type
  • regenerator type
Q.21

Thermal diffusivity of a substance is

  • directly proportional to the thermal conductivity
  • inversely proportional to density of substance
  • inversely proportional to specific heat
  • all of the above
Q.22

Thermal diffusivity of a substance is given by (where h = Thermal diffusivity, ρ = Density of substance, S = Specific heat, and k = Thermal conductivity)

Q.23

For a white body, absorptivity (α ) =reflectivity (ρ) = 1 and transmittivity (τ) = 0.

  • Correct
  • Incorrect
Q.24

Bell-Coleman cycle is a

  • reversed Carnot cycle
  • reversed Otto cycle
  • reversed Joule cycle
  • reversed Rankine cycle
Q.25

The horizontal and uniformly spaced lines on a psychrometric chart indicates relative humidity.

  • Correct
  • Incorrect
Q.26

Which of the following statement is correct for ammonia as a refrigerant?

  • It is toxic to mucous membranes.
  • it requires large displacement per TR compared to fluoro carbons.
  • It reacts with copper and its alloys.
  • all of these
Q.27

The counter-current flow heat exchanger can transfer __________ heat than parallel flow heat exchanger.

  • less
  • more
Q.28

The freon group of refrigerants are

  • halo-carbon refrigerants
  • azeotrope refrigerants
  • inorganic refrigerants
  • hydro-carbon refrigerants
Q.29

In mechanical refrigeration system, the refrigerant occurs as liquid between condenser and expansion valve.

  • True
  • False
Q.30

Which of the following statement is correct for ammonia as a refrigerant?

  • It is toxic to mucous membranes.
  • it requires large displacement per TR compared to fluoro carbons.
  • It reacts with copper and its alloys.
  • all of these
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