The mass of water vapour present in __________ is called absolute humidity.
1 m3 of water
1 m3 of dry air
1 kg of wet air
1 kg of dry air
Correct Answer :
B. 1 m3 of dry air
Related Questions
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
Which of the following is not a desirable property of a refrigerant?
High risibility with oil
Low boiling point
Good electrical conductor
Large latent heat
The specific humidity during cooling and dehumidification
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.
Air refrigeration cycle is used in
Domestic refrigerators
Commercial refrigerators
Air conditioning
Gas liquefaction
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
The advantage of dry compression is that
It permits higher speeds to be used
It permits complete evaporation in the evaporator
It results in high volumetric and mechanical efficiency
All of the above
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
For obtaining high COP, the pressure range of compressor should be
High
Low
Optimum
Any value
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 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
Air refrigeration operates on
Carnot cycle
Reversed Carnot cycle
Rankines cycle
Brayton cycle
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
The reduced ambient air cooling system has
One cooling turbine and one heat exchanger
One cooling turbine and two heat exchangers
Two cooling turbines and one heat exchanger
Two cooling turbines and two heat exchangers
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
The freezing point of R-12 is
-86.6°C
-95.2°C
-107.7°C
-135.8°C
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
While designing the refrigeration system of an aircraft, the prime consideration is that the
System has high C.O.P.
Power per TR is low
Mass of refrigerant circulated in the system is low
Mass of the refrigeration equipment is low
The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy diagram represents
Condensation of the refrigerant vapour
Evaporation of the refrigerant liquid
Compression of the refrigerant vapour
Metering of the refrigerant liquid
In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to
Collect liquid refrigerant and prevent it from going to compressor
Detect liquid in vapour
Superheat the vapour
Collect vapours
During adiabatic saturation process on unsaturated air __________ remains constant.
Relative humidity
Dew point temperature
Dry bulb temperature
Wet bulb temperature
In a reversed Brayton cycle, the heat is absorbed by the air during
Isentropic compression process
Constant pressure cooling process
Isentropic expansion process
Constant pressure expansion process
During dehumidification process, the relative humidity
Remains constant
Increases
Decreases
None of these
The bypass factor of a cooling coil decreases with
Decrease in fin spacing and increase in number of rows
Increase in fin spacing and increase in number of rows
Increase in fin spacing and decrease in number of rows
Decrease in fin spacing and decrease in number of rows
The refrigerant widely used in domestic refrigerators is
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
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, is called
Humidity ratio
Relative humidity
Absolute humidity
Degree of saturation
Most air cooled condensers are designed to operate with a temperature difference of
5°C
8°C
14°C
22°C
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
In a psychrometric chart, specific humidity (moisture content) lines are
Vertical and uniformly spaced
Horizontal and uniformly spaced
Horizontal and non-uniformly spaced
Curved lines
In which of the following refrigeration system, waste heat can be effectively used?
Vapour compression cycle
Vapour absorption cycle
Air refrigeration cycle
None of these