Q.1

A grey body is one whose absorptivity does not vary with temperature and wave length of the incident ray.

  • True
  • False
Q.2

The wet bulb temperature during sensible cooling of air

  • remains constant
  • increases
  • decreases
Q.3

The superheated vapour region, in a pressure enthalpy chart, is represented by the space

  • to the left of saturated liquid line
  • to the right of saturated liquid line
  • between the saturated liquid line and saturated vapour line
  • none of the above
Q.4

Which of the following refrigerant has the maximum ozone depletion potential in the stratophere?

  • Ammonia
  • Carbon dioxide
  • Sulphur dioxide
  • Flourine
Q.5

The C.O.P. of a Carnot refrigerator in winter will be __________ as compared to C.O.P. in summer.

  • same
  • lower
  • higher
Q.6

A boot-strap air cooling system has

  • one heat exchanger
  • two heat exchangers
  • three heat exchangers
  • four heat exchangers
Q.7

The thermostatic expansion valve operates on the changes in the

  • degree of superheat at exit from the evaporator
  • temperature of the evaporator
  • pressure in the evaporator
  • none of the above
Q.8

The sensible heat during humidification process decreases.

  • True
  • False
Q.9

Thermal conductivity of a material may be defined as the

  • quantity of heat flowing in one second through a slab of the material of area 1 cm2 and thickness 1 cm when its faces differ in temperature by 1° C
  • quantity of heat flowing in one second through one cm of material when opposite faces are maintained at a temperature difference of 1° C
  • heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces
  • all of the above
Q.10

The desirable property of a refrigerant is

  • low boiling point
  • high critical temperature
  • high latent heat of vaporisation
  • all of these
Q.11

In a boot-strap air evaporative cooling system, the evaporator is provided

  • between the combustion chamber and the first heat exchanger
  • between the first heat exchanger and the secondary compressor
  • between the secondary compressor and the second heat exchanger
  • between the second heat exchanger and the cooling turbine
Q.12

In absorption vapour systems, the refrigerant widely used is R-12.

  • Correct
  • Incorrect
Q.13

The minimum temperature to which water can be cooled in a cooling tower is

  • dew point temperature of air
  • wet bulb temperature of air
  • dry bulb temperature of air
  • ambient air temperature
Q.14

Which of the following statement is correct?

  • The constant enthalpy lines are also constant wet bulb temperature lines.
  • The wet bulb and dry bulb temperature are equal at saturation condition.
  • The wet bulb temperature is a measure of enthalpy of moist air.
  • all of the above
Q.15

Which of the following statement is correct?

  • The human body can lose heat even if its temperature is less than the atmospheric temperature.
  • The increase in air movement increases the evaporation from the human body.
  • The warm air increases the rate of radiation of heat from the human body.
  • both (a) and (b)
Q.16

The boiling point of __________ is -10.5°C.

  • ammonia
  • R-12
  • sulphur dioxide
  • carbon dioxide
Q.17

In a vapour compression system, the condition of refrigerant before entering the expansion or throttle valve is

  • high pressure saturated liquid
  • wet vapour
  • very wet vapour
  • dry vapour
Q.18

According to Newton's law of cooling, the heat transfer from a hot body to a cold body is

  • directly proportional to the surface area
  • directly proportional to the difference of temperatures between the two bodies
  • either (a) or (b)
  • both (a) and (b)
Q.19

During sensible heating of air, specific humidity remains constant.

  • Agree
  • Disagree
Q.20

The condition of refrigerant after passing through the expansion or throttle valve, in a vapour compression system is

  • high pressure saturated liquid
  • wet vapour
  • very wet vapour
  • dry vapour
Q.21

In a shell and coil condenser, water flows in the shell and the refrigerant in the coil.

  • True
  • False
Q.22

In counter-current flow heat exchanger, the logarithmic temperature difference between the fluids is __________ as compared to parallel flow heat exchanger.

  • same
  • less
  • greater
Q.23

The humidification process, on the psychrometric chart is shown by

  • horizontal line
  • vertical line
  • inclined line
  • curved line
Q.24

According to Stefan-Boltzmann law, the total radiation from a black body per second per unit area is directly proportional to the

  • absolute temperature
  • square of the absolute temperature
  • cube of the absolute temperature
  • fourth power of the absolute temperature
Q.25

Hydrogen is used in electrolux refrigeration system so as to __________ the rate of evaporation of the liquid ammonia passing through the evaporator.

  • equalise
  • reduce
  • increase
Q.26

The index which corelates the combined effects of air temperature, relative humidity and air velocity on the human body, is known as

  • mean radiant temperature
  • effective temperature
  • dew point temperature
  • none of these
Q.27

According to Stefan's law, the total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature.

  • Correct
  • Incorrect
Q.28

The heat is transferred by conduction, convection and radiation in

  • melting of ice
  • boiler furnaces
  • condensation of steam in condenser
  • none of these
Q.29

The expansion valve in a refrigerator controls the flow of refrigerant.

  • Correct
  • Incorrect
Q.30

Dehydration is the process of removing water vapour from the surrounding air.

  • True
  • False
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