The curved lines on a psychrometric chart indicates
Dry bulb temperature
Wet bulb temperature
Dew point temperature
Relative humidity
Correct Answer :
D. Relative humidity
Related Questions
Which of the following statement is wrong?
The value of C.O.P. is always greater than one.
In a vapour compression system, the condition of refrigerant before entering the compressor is dry saturated vapour.
The space between the saturated liquid line and saturated vapour line, in a pressure enthalpy chart, is wet vapour region.
None of the above
A human body feels comfortable when the heat produced by the metabolism of human body is equal to the
Heat dissipated to the surroundings
Heat stored in the human body
Sum of (A) and (B)
Difference of (A) and (B)
The desirable property of a refrigerant is
Low boiling point
High critical temperature
High latent heat of vaporisation
All of these
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
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 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
Highest pressure encountered in a refrigeration system should be
Critical pressure of refrigerant
Much below critical pressure
Much above critical pressure
Near critical pressure
The reciprocating refrigerant compressors are very suitable for
Small displacements and low condensing pressures
Large displacements and high condensing pressures
Small displacements and high condensing pressures
Large displacements and low condensing pressures
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
The refrigerant widely used in domestic refrigerators is
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
The refrigeration effect in a dry evaporator compared to flooded evaporator in a similar plant is
Same
More
Less
More or less depending on ambient conditions
The thermostatic expansion valve is used in __________ type of evaporators.
Flooded
DX coil
Dry
None of these
Moisture in Freon refrigeration system causes
Ineffective refrigeration
High power consumption
Freezing automatic regulating valve
Corrosion of whole system
The boiling point of carbon dioxide is
-20.5°C
-50°C
-63.3°C
-78.3°C
Refrigeration in aeroplanes usually employs the following refrigerant
CO2
Freon-11
Freon-22
Air
Choose the wrong statement
Temperature of medium being cooled must be below that of the evaporator
Refrigerant leaves the condenser as liquid
All solar thermally operated absorption systems are capable only of intermittent operation
Frost on evaporator reduces heat transfer
A pressure gauge on the discharge side of a refrigerant compressor reads too high. The reasons will be
Lack of cooling water
Water temperature being high
Dirty condenser surface
All 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
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
A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67 kg/cm. The refrigerant used is
Ammonia
Carbon dioxide
Freon
Brine
The wet bulb temperature during sensible cooling of air
Remains constant
Increases
Decreases
None of these
In aircraft, air refrigeration Cycle is used because of
Low weight per tonne of refrigeration
High heat transfer rate
Low temperature at high altitudes
Higher coefficient of performance
Air refrigeration cycle is used in
Domestic refrigerators
Commercial refrigerators
Air conditioning
Gas liquefaction
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
During cooling and dehumidification, dry bulb temperature
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
A Bell Coleman refrigerator working on dense air system as compared to open air system, for the same range of temperature, results in ________ power per tonne of refrigeration.
Same
Lower
Higher
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
Rating of a domestic refrigerator is of the order of
0.1 ton
5 tons
10 tons
40 tons
If a heat pump cycle operates between the condenser temperature of +27°C and evaporator temperature of -23°C, then the Carnot COP will be
0.2
1.2
5
6