The moisture in a refrigerant is removed by
Evaporator
Safety relief valve
Dehumidifier
Driers
Correct Answer :
D. Driers
Related Questions
During sensible heating of air _________ decreases.
Wet bulb temperature
Relative humidity
Dry bulb temperature
Specific humidity
During sensible cooling,
Relative humidity remains constant
Wet bulb temperature increases
Specific humidity increases
Partial pressure of vapour remains constant
For better C.O.P of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be
Small
High
Equal
Anything
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
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
At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant
Decreases
Increases
Remain same
Depends on other factors
On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process
Involves no change in volume
Takes place at constant temperature
Takes place at constant entropy
Takes place at constant pressure
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 difference between dry bulb temperature and wet bulb temperature, is called
Dry bulb depression
Wet bulb depression
Dew point depression
Degree of saturation
The vertical and uniformly spaced lines on a psychrometric chart indicates
Dry bulb temperature
Wet bulb temperature
Dew point temperature
Specific humidity
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
An infinite parallel planes with emissivities e₁ and e₂, the interchange factor for radiation from surface 1 to surface 2 is given by
(e₁ + e₂)/ e₁ + e₂ - e₁e₂
1/e₁ + 1/e₂
e₁ + e₂
e₁e₂
The thermostatic expansion valve operates on the changes in the
Degree of superheat at exit from the evaporator
Temperature of the evaporator
Pressure in the evaporator
None of the above
The central air conditioning system has ________ overall efficiency as compared to individual systems.
Same
Lower
Higher
None of these
The optimum effective temperature for human comfort is
Higher in winter than in summer
Lower in winter than in summer
Same in winter and summer
Not dependent on season
In Electrolux refrigerator
Ammonia is absorbed in hydrogen
Ammonia is absorbed in water
Ammonia evaporates in hydrogen
Hydrogen evaporates in ammonia
The wet bulb depression indicates _________ humidity of the air.
Absolute
Relative
Specific
None of these
The wet bulb temperature at 100% relative humidity is ________ dew point temperature.
Same as
Lower than
Higher than
None of these
The bypass factor (B. P. F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil, and td₃ = Dry bulb temperature of heating coil)
(td₂ - td₃)/(td₃ - td₁)
(td₃ - td₂)/(td₃ - td₁)
(td₃ - td₁)/(td₂ - td₃)
(td₃ - td₁)/(td₃ - td₂)
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 refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called
Sub-cooling or under-cooling
Super-cooling
Normal cooling
None of these
The formation of frost on cooling coils in a refrigerator
Increases heat transfer
Improves C.O.P. of the system
Increases power consumption
Reduces power consumption
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 material of pipe lines for a system using Freon as a refrigerant should be
Brass
Copper
Steel
Aluminium
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
Carbon dioxide is
Colourless
Odourless
Non-flammable
All of these
Which of the following refrigerant has the lowest freezing point?
R-11
R-12
R-22
Ammonia
The refrigerant used in small tonnage commercial machines (hermetically sealed units) is
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
Where does the lowest temperature occur in a vapour compression cycle?
Condenser
Evaporator
Compressor
Expansion valve
Refrigeration in aeroplanes usually employs the following refrigerant
CO2
Freon-11
Freon-22
Air