Air refrigeration cycle is used in
Commercial refrigerators
Domestic refrigerators
Air-conditioning
Gas liquefaction
Correct Answer :
D. Gas liquefaction
Related Questions
Critical temperature is the temperature above which
A gas will never liquefy
A gas will immediately liquefy
Water will evaporate
Water will never evaporate
The horizontal and non-uniformly spaced lines on a psychrometric chart indicates
Dry bulb temperature
Wet bulb temperature
Dew point temperature
Specific humidity
The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure, is called
Humidity ratio
Relative humidity
Absolute humidity
Degree of saturation
Moisture in Freon refrigeration system causes
Ineffective refrigeration
High power consumption
Freezing automatic regulating valve
Corrosion of whole system
The condition of refrigerant as it leaves the compressor in a vapour compression system is
Saturated liquid
Wet vapour
Dry saturated vapour
Superheated vapour
Which of the following statement is wrong?
The performance of the vapour compression refrigerator varies considerably with both vaporising and condensing temperatures.
In vapour compression cycle, the useful part of the heat transfer is at the condenser.
In ammonia-hydrogen (Electrolux) refrigerator, no compressor, pump or fan is required.
The effect of under-cooling the liquid refrigerant is to decrease the coefficient of performance.
The boiling point of ammonia is
-10.5°C
-30°C
-33.3°C
-77.7°C
A refrigerant with the highest critical pressure is
R-11
R-12
R-22
Ammonia
During sensible cooling of air, specific humidity
Remains constant
Increases
Decreases
None of these
Mass flow ratio of NH₃ in comparison to Freon12 for same refrigeration load and same temperature limits is of the order of
1 : 1
1 : 9
9 : 1
1 : 3
The evolution of heat of solution takes place in ammonia absorption plant when
Ammonia vapour goes into solution
Ammonia vapour is driven out of solution
Lithium bromide mixes with ammonia
Weak solution mixes with strong solution
When the temperature of the surrounding is higher than the temperature of the body, then the heat loss by convection from the body to the surrounding will be
Positive
Negative
Zero
None of these
The lowest thermal diffusivity is of
Iron
Lead
Aluminium
Rubber
The bypass factor, in case of sensible cooling of air, is given by (where td₁ = Dry bulb temperature of air entering the cooling coil, td₂ = Dry bulb temperature of air leaving the cooling coil, and td₃ = Dry bulb temperature of the cooling coil)
(td₁ -td₃)/( td₂ -td₃)
(td₂ -td₃)/( td₁ -td₃)
(td₃ -td₁)/( td₂ -td₃)
(td₃ -td₂)/( td₁ -td₃)
The leaks in a refrigeration system using Freon are detected by
Halide torch which on detection produces greenish flame lighting
Sulphur sticks which on detection gives white smoke
Using reagents
Smelling
Air refrigeration cycle is used in
Domestic refrigerators
Commercial refrigerators
Air conditioning
Gas liquefaction
The total pressure exerted by the mixture of air and water vapour is equal to the sum of pressures which each constituent would exert, if it occupied the same space by itself. This statement is called
Kinetic theory of gases
Newton's law of gases
Dalton's law of partial pressures
Avogadro's hypothesis
In a vapour compression system, the condition of refrigerant before passing through the condenser is
Saturated liquid
Wet vapour
Dry saturated vapour
Superheated vapour
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
The relative humidity is defined as
The mass of water vapour present in 1 m3 of dry air
The mass of water vapour present in 1 kg of dry air
The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure.
The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure
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
Pressure of water vapour is given by
0.622 Pv/ (Pb - Pv)
μ/[1 - (1 - μ) (Ps/Pb)]
[Pv (Pb - Pd)]/ [Pd (Pb - Pv)]
None of these
Wet bulb temperature is the temperature of air recorded by a thermometer, when
It is not affected 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
One of the purposes of sub cooling the liquid refrigerant is to
Reduce compressor overheating
Reduce compressor discharge temperature
Increase cooling effect
Ensure that only liquid and not the vapour enters the expansion (throttling) valve
At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant
Decreases
Increases
Remain same
Depends on other factors
Ammonia absorption refrigeration cycle requires
Very little work input
Maximum work input
Nearly same work input as for vapour compression cycle
Zero work input
Efficiency of a Carnot engine is given as 80%. If the cycle direction be reversed, what will be the value of COP of reversed Carnot Cycle?
1.25
0.8
0.5
0.25
The capillary tube is not used in large capacity refrigeration systems because
Cost is too high
Capacity control is not possible
It is made of copper
Required pressure drop cannot be achieved
In a refrigerating machine, heat rejected is _________ heat absorbed.
Equal to
Less than
Greater than
None of these
The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is
Bigger
Smaller
Equal
Smaller/bigger depending on capacity