The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will
Increase
Decrease
Remain unaffected
May increase or decrease depending on the type of refrigerant used
Correct Answer :
A. Increase
Related Questions
A good refrigerant should have
High latent heat of vaporisation and low freezing point
High operating pressures and low freezing point
High specific volume and high latent heat of vaporisation
Low C.O.P. and low freezing point
Vapour compression refrigeration is somewhat like
Carnot cycle
Rankines cycle
Reversed Carnot cycle
None of the above
The bank of tubes at the back of domestic refrigerator is
Condenser tubes
Evaporator tubes
Refrigerant cooling tubes
Capillary tubes
The comfort conditions in air conditioning are at (where DBT = Dry bulb temperature, and RH = Relative humidity)
25°C DBT and 100% RH
20°C DBT and 80% RH
22°C DBT and 60% RH
25°C DBT and 40% RH
A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigerating machine with all other conditions unchanged, the coefficient of performance will be
1.33
2.33
3.33
4.33
The specific humidity during humidification process
Remains constant
Increases
Decreases
None of these
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 wet bulb temperature during sensible cooling of air
Remains constant
Increases
Decreases
None of these
In case of sensible cooling of air, the coil efficiency is given by
B.P.F. - 1
1 - B.P.F.
1/ B.P.F.
1 + B.P.F.
The cooling system used for supersonic aircrafts and rockets is
Simple air cooling system
Bootstrap air cooling system
Reduced ambient air cooling system
Regenerative air cooling system
One ton refrigeration corresponds to
50 kcal/ min
50 kcal/ hr
80 kcal/ min
80 kcal/ hr
The C.O.P. of a heat pump working on a reversed Carnot cycle is
T₁/(T₂ - T₁)
(T₂ - T₁)/T₁
(T₁ - T₂)/T₁
T₂/(T₂ - T₁)
In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is
Heated and dehumidified
Heated and humidified
Cooled and humidified
Cooled and dehumidified
Air refrigeration operates on
Carnot cycle
Reversed Carnot cycle
Rankines cycle
Brayton cycle
The human body feels comfortable when the heat stored in the body is
Positive
Negative
Zero
None of these
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
None of these
The specific humidity during heating and humidification process.
Remains constant
Increases
Decreases
None of these
The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will
Increase
Decrease
Remain unaffected
May increase or decrease depending on the type of refrigerant used
The thermostatic expansion valve is used in __________ type of evaporators.
Flooded
DX coil
Dry
None of these
The unit of thermal diffusivity is
m/hK
m/h
m²/h
m²/hK
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
Rick up the incorrect statement
Lithium bromide used in vapour absorption cycle is non volatile
Lithium bromide plant can't operate below 0°C
A separator is used in lithium bromide plant to remove the unwanted water vapour by condensing
Concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator
A thermostatic expansion valve in a refrigeration system
Ensures the evaporator completely filled with refrigerant of the load
Is suitable only for constant load systems
Maintains different temperatures in evaporator in proportion to load
None of the above
Dry 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
A vapour absorption refrigeration system
Gives noisy operation
Gives quiet operation
Requires little power consumption
Cools below 0°C
Moisture in Freon refrigeration system causes
Ineffective refrigeration
High power consumption
Freezing automatic regulating valve
Corrosion of whole system
The refrigerant used for absorption refrigerators working on heat from solar collectors is a mixture of water and
Carbon dioxide
Sulphur dioxide
Lithium bromide
R-12
The ratio of heat extracted in the refrigerator to the work-done on the refrigerant is called
Coefficient of performance of refrigeration
Coefficient of performance of heat pump
Relative coefficient of performance
Refrigerating efficiency
The leakage in a refrigeration system using ammonia is detected by
Halide torch
Sulphur sticks
Soap and water
All of these
In a domestic vapour compression refrigerator, the refrigerant commonly used is
CO₂
Ammonia
R-12
All of these