Refrigeration in aeroplanes usually employs the following refrigerant
CO2
Freon-11
Freon-22
Air
Correct Answer :
D. Air
Related Questions
The lowest thermal diffusivity is of
Iron
Lead
Aluminium
Rubber
The material of pipe lines for a system using Freon as a refrigerant should be
Brass
Copper
Steel
Aluminium
Air refrigeration cycle is used in
Commercial refrigerators
Domestic refrigerators
Air-conditioning
Gas liquefaction
The COP of a vapour compression plant in comparison to vapour absorption plant is
More
Less
Same
More/less depending on size of plant
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
The vapour pressure of refrigerant should be
Lower than atmospheric pressure
Higher than atmospheric pressure
Equal to atmospheric pressure
Could be anything
Which of the following refrigerant has the highest freezing point.
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
The boiling point of carbon dioxide is
-20.5°C
-50°C
-63.3°C
-78.3°C
One ton refrigeration corresponds to
50 kcal/ min
50 kcal/ hr
80 kcal/ min
80 kcal/ hr
The boiling point of ________ is 10.5°C.
Ammonia
R-12
Sulphur dioxide
Carbon dioxide
The C.O.P. of an absorption type refrigerator is given by (where T₁ = Temperature at which the working substance receives heat, T₂ = Temperature of cooling water, and T₃ = Evaporator temperature)
[T₁ (T₂ - T₃)] / [T₃ (T₁ - T₂)]
[T₃ (T₁ - T₂)]/ [T₁ (T₂ - T₃)]
[T₁ (T₁ - T₂)] / [T₃ (T₂ - T₃)]
[T₃ (T₂ - T₃)] / [T₁ (T₁ - T₂)]
The power per tonne of refrigeration is
3.5/C.O.P.
C.O.P/3.5
3.5 × C.O.P.
None of these
During a refrigeration cycle, heat is rejected by the refrigerant in a
Compressor
Condenser
Evaporator
Expansion valve
A one tonne refrigerating machine means that
One tonne is the total mass of machine
One tonne refrigerant is used
One tonne of water can be converted into ice
One tonne of ice when melts from and at 0° C in 24 hours, the refrigeration effect is equivalent to 210 kJ/min
Which of the following refrigerants has lowest freezing point?
Freon-12
NH3
CO2
Freon-22
The capillary tube, as an expansion device, is used in
Domestic refrigerators
Water coolers
Room air conditioners
All of these
The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P.
More
Less
Equally
Unpredictable
The air cooling system mostly used in transport type aircrafts is
Simple air cooling system
Simple evaporative air cooling system
Bootstrap air cooling system
All of these
Chaperon equation is a relation between
Temperature, pressure and enthalpy
Specific volume and enthalpy
Temperature and enthalpy
Temperature, pressure, specific volume and enthalpy
During heating and dehumidification process, dry bulb temperature
Remains constant
Increases
Decreases
None of these
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
The temperature of ammonia after compression in a vapour compression system is
20 to 50°C
50 to 70°C
70 to 110°C
None of these
If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be
Same
More
Less
More/less depending on rating
Formation of frost on evaporator in refrigerator
Results in loss of heat due to poor heat transfer
Increases heat transfer rate
Is immaterial
Can be avoided by proper design
Most air cooled condensers are designed to operate with a temperature difference of
5°C
8°C
14°C
22°C
Carbon dioxide is
Colourless
Odourless
Non-flammable
All of these
An Electrolux refrigerator is called a __________ absorption system.
Single fluid
Two fluids
Three fluids
None of these
The fluids used in Electrolux refrigerator are
Water and hydrogen
Ammonia and hydrogen
Ammonia, water and hydrogen
None of these
One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice
In 1 hour
In 1 minute
In 24 hours
In 12 hours
The specific humidity during cooling and dehumidification
Remains constant
Increases
Decreases
None of these