Vertical lines on pressure-enthalpy chart show constant
Pressure lines
Temperature lines
Total heat lines
Entropy lines
Correct Answer :
C. Total heat lines
Related Questions
Which of the following refrigerant has the lowest boiling point?
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
Air refrigeration cycle is used in
Commercial refrigerators
Domestic refrigerators
Air-conditioning
Gas liquefaction
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
The boiling point of ________ is 10.5°C.
Ammonia
R-12
Sulphur dioxide
Carbon dioxide
During sensible heating of air _________ decreases.
Wet bulb temperature
Relative humidity
Dry bulb temperature
Specific humidity
For obtaining high COP, the pressure range of compressor should be
High
Low
Optimum
Any value
In a bootstrap 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
The boiling point of ammonia is
100°C
50°C
33.3°C
0°C
The humidity ratio or specific humidity is the mass of water vapour present in
1 m3 of wet air
1 m3 of dry air
1 kg of wet air
1 kg of dry air
Under cooling in a refrigeration cycle
Increases C.O.P
Decreases C.O.P
C.O.P remains unaltered
Other factors decide C.O.P
In aqua ammonia absorption refrigeration system, incomplete rectification leads to accumulation of water in
Condenser
Evaporator
Absorber
None of these
In a pressure enthalpy chart, the space to the left of the saturated liquid line represents
Wet vapour region
Superheated vapour region
Sub-cooled liquid region
None of these
The pressure at the outlet of a refrigerant compressor is called
Suction pressure
Discharge pressure
Critical pressure
Back pressure
One ton of the refrigeration is
The standard unit used in refrigeration problems
The cooling effect produced by melting 1 ton of ice
The refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours
The refrigeration effect to produce 1 ton of ice at NTP conditions
In a refrigerating machine, heat rejected is _________ heat absorbed.
Equal to
Less than
Greater than
None of these
The evaporator used in household refrigerators is
Frosting evaporator
Non-frosting evaporator
Defrosting evaporator
None of these
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 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
The freezing point of sulphur dioxide is
-56.6°C
-75.2°C
-77.7°C
-135.8°C
Which of the following statement is correct for ammonia as a refrigerant?
It is toxic to mucous membranes.
It requires large displacement per TR compared to fluoro carbons.
It reacts with copper and its alloys.
All of these
An evaporator is also known as
Freezing coil
Cooling coil
Chilling coil
All of these
The coefficient of performance is the ratio of the refrigerant effect to the
Heat of compression
Work done by compressor
Enthalpy increase in compressor
All of the above
Moisture in Freon refrigeration system causes
Ineffective refrigeration
High power consumption
Freezing automatic regulating valve
Corrosion of whole system
In a vapour compression system, the condition of refrigerant before passing through the condenser is
Saturated liquid
Wet vapour
Dry saturated vapour
Superheated vapour
As relative humidity decreases, the dew point temperature will be ________ wet bulb temperature.
Same as
Lower than
Higher than
None of these
The relative humidity lines on a psychrometric chart are
Vertical and uniformly spaced
Horizontal and uniformly spaced
Horizontal and non-uniformly spaced
Curved lines
The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will
Increase
Decrease
May increase or decrease depending on the type of refrigerant used
Remain unaffected
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
The wet bulb depression indicates _________ humidity of the air.
Absolute
Relative
Specific
None of these
During heating and humidification, the final relative humidity of air
Can be lower or higher than that of the entering air
Is lower than that of the entering air
Is higher than that of the entering air
None of the above