Which of the following statement is correct?
In vapour absorption refrigerator, the compression of refrigerant is avoided.
Sub-cooling can be achieved by circulating more quantity of cooling water through the condenser.
In vapour compression refrigeration, the vapour is drawn in the compressor cylinder during its suction stroke and is compressed adiabatically during the compression stroke.
All of the above
Correct Answer :
D. All of the above
Related Questions
Freon group of refrigerants are
Inflammable
Toxic
Non-inflammable and toxic
Nontoxic and non-inflammable
The general rule for rating refrigeration systems (excepting for CO₂ system) is to approximate following h.p. per ton of refrigeration
0.1 to 0.5 h.p. per ton of refrigeration
0.5 to 0.8 h.p. per ton of refrigeration
1 to 2 h.p. per ton of refrigeration
2 to 5 h.p. per ton of refrigeration
In vapour compression refrigeration system, refrigerant occurs as liquid between
Condenser and expansion valve
Compressor and evaporator
Expansion valve and evaporator
Compressor and condenser
The alignment circle is marked on the psychrometric chart at
20°C DBT and 50% RH
26°C DBT and 50% RH
20°C DBT and 60% RH
26°C DBT and 60% RH
The fluids used in Electrolux refrigerator are
Water and hydrogen
Ammonia and hydrogen
Ammonia, water and hydrogen
None of these
The value of C.O.P in vapour compression cycle is usually
Always less than unity
Always more than unity
Equal to unity
Any one of the above
One ton refrigeration corresponds to
50 kcal/ min
50 kcal/ hr
80 kcal/ min
80 kcal/ hr
The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T₁ = Lowest absolute temperature, and T₂ = Highest absolute temperature)
T₁ / (T₂ - T₁)
(T₂ - T₁)/T₁
(T₁ - T₂)/T₁
T₂/ (T₂ - T₁)
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
During dehumidification process, the relative humidity
Remains constant
Increases
Decreases
None of these
Relative humidity is given by (where pv = Partial pressure of water vapour, pb = Barometric pressure, ps = Pressure of saturated air, pd = Pressure at dry bulb temperature, pw = Saturation pressure corresponding to wet bulb temperature, and μ = Degree of saturation)
0.622 Pv / (Pb - Pv)
μ/[1 - (1 - μ) (Ps/Pb)]
[Pv (Pb - Pd)]/ [Pd (Pb - Pv)]
None of these
A condenser of refrigeration system rejects heat at the rate of 120 kW, while its compressor consumes a power of 30 kW. The coefficient of performance of the system will be
1/4
1/3
3
4
During humidification process, __________ increases.
Wet bulb temperature
Relative humidity
Dry bulb temperature
Specific humidity
Environmental protection agencies advice against the use of chlorofluorocarbon refrigerants since
These react with water vapour and cause acid rain
These react with plants and cause greenhouse effect
These react with oxygen and cause its depletion
These react with ozone layer
For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is ________ that for counter flow.
Equal to
Less than
Greater than
None of these
Where does the lowest temperature occur in a vapour compression cycle?
Condenser
Evaporator
Compressor
Expansion valve
A vapour absorption refrigerator uses __________ as a refrigerant.
Water
Ammonia
Freon
Aqua-ammonia
Air refrigerator works on
Reversed Carnot cycle
Bell Coleman cycle
Both (A) and (B)
None of these
Most of the domestic refrigerators work on the following refrigeration system
Vapour compression
Vapour absorption
Carnot cycle
Electrolux refrigerator
In a refrigeration system, heat absorbed in comparison to heat rejected is
More
Less
Same
More for small capacity and less for high capacity
The thermal diffusivity for gases is generally __________ those for liquids.
Equal to
Less than
Greater than
None of these
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
In vapour compression cycle using NH₃ as refrigerant, initial charge is filled at
Suction of compressor
Delivery of compressor
High pressure side close to receiver
Low pressure side near receiver
A refrigerant with the highest critical pressure is
R-11
R-12
R-22
Ammonia
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
When the air is passed through an insulated chamber having sprays of water maintained at a temperature higher than the dew point temperature of entering air but lower than its dry bulb temperature, then the air is said to be
Cooled and humidified
Cooled and dehumidified
Heated and humidified
Heated and dehumidified
In actual air-conditioning applications for R-12 and R-22, and operating at a condenser temperature of 40° C and an evaporator temperature of 5° C, the heat rejection factor is about
1
1.25
2.15
5.12
An Electrolux refrigerator is called a __________ absorption system.
Single fluid
Two fluids
Three fluids
None of these
If a gas is to be liquefied, its temperature must be
Increased to a value above its critical temperature
Reduced to a value below its critical temperature
Equal to critical temperature
None of the above
The COP of a domestic refrigerator
Is less than 1
Is more than 1
Is equal to 1
Depends upon the make