In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the
Expansion valve to the evaporator
Evaporator to the thermostat
Condenser to the expansion valve
Condenser to the evaporator
Correct Answer :
A. Expansion valve to the evaporator
Related Questions
The wet bulb depression indicates _________ humidity of the air.
Absolute
Relative
Specific
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
The boiling point of ammonia is
-10.5°C
-30°C
-33.3°C
-77.7°C
The relative coefficient of performance is equal to
(Theoretical C.O.P.)/ (Actual C.O.P.)
(Actual C.O.P.) /(Theoretical C.O.P.)
(Actual C.O.P.) × (Theoretical C.O.P.)
None of these
For obtaining high COP, the pressure range of compressor should be
High
Low
Optimum
Any value
Which of the following refrigerants has lowest freezing point?
Freon-12
NH3
CO2
Freon-22
R-12 is generally preferred over R-22 in deep freezers since
It has low operating pressures
It gives higher coefficient of performance
It is miscible with oil over large range of temperatures
All of the above
The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases,
Will be higher
Will be lower
Will remain unaffected
May be higher or lower depending upon the nature of noncondensable gases
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 sensible heat factor during the heating and humidification process is given by (where h₁ = Enthalpy of air entering the heating coil, h₂ = Enthalpy of air leaving the heating coil, and hA = Enthalpy of air at the end of humidification process)
(hA - h2)/ (h1 - h2)
(h2 - hA)/ (h1 - h2)
(h1 - h2)/ (hA - h2)
(hA - h1)/ (h2 - h1)
The heat rejection factor (HRF) is given by
1 + C.O.P
1 - C.O.P.
1 + (1/C.O.P)
1 - (1/C.O.P)
The COP of a vapour compression plant in comparison to vapour absorption plant is
More
Less
Same
More/less depending on size of plant
The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P.
More
Less
Equally
Unpredictable
The COP of a domestic refrigerator
Is less than 1
Is more than 1
Is equal to 1
Depends upon the make
The pressure at the inlet of a refrigerant compressor is called
Suction pressure
Discharge pressure
Critical pressure
Back pressure
Most of the domestic refrigerators work on the following refrigeration system
Vapour compression
Vapour absorption
Carnot cycle
Electrolux refrigerator
It is desired to condition the outside air from 70% relative humidity and 45° C dry bulb temperature to 50% relative humidity and 25° C dry bulb temperature (room condition). The practical arrangement will be
Dehumidification
Cooling and humidification
Cooling and dehumidification
Dehumidification and pure sensible cooling
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
Absorption system normally uses the following refrigerant
Freon-11
Freon-22
CO2
Ammonia
The bypass factor for a cooling coil
Increases with increase in velocity of air passing through it
Decreases with increase in velocity of air passing through it
Remains unchanged with increase in velocity of air passing through it
May increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering
In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is
Heated and dehumidified
Heated and humidified
Cooled and humidified
Cooled and dehumidified
The thermal diffusivity for gases is generally __________ those for liquids.
Equal to
Less than
Greater than
None of these
In vapour compression cycle, the condition of refrigerant is saturated liquid
After passing through the condenser
Before passing through the condenser
After passing through the expansion throttle valve
Before entering the expansion valve
The boiling point of carbon dioxide is
-20.5°C
-50°C
-63.3°C
-78.3°C
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 operating temperature of a cold storage is 2°C. The heat leakage from the surrounding is 30 kW for the ambient temperature of 40°C. The actual C.O.P. of refrigeration plant used is one fourth that of ideal plant working between the same temperatures. The power required to drive the plant is
1.86 kW
3.72 kW
7.44 kW
18.6 kW
During dehumidification process, the relative humidity
Remains constant
Increases
Decreases
None of these
In air-conditioning of aeroplanes, using air as a refrigerant, the cycle used is
Reversed Carnot cycle
Reversed Joule cycle
Reversed Brayton cycle
Reversed Otto cycle
The air cooling system mostly used in transport type aircrafts is
Simple air cooling system
Simple evaporative air cooling system
Bootstrap air cooling system
All of these
In a vapour compression refrigeration system, a throttle valve is used in place of an expander because
It considerably reduces mass of the system
It improves the C.O.P., as the condenser is small
The positive work in isentropic expansion of liquid is very small
It leads to significant cost reduction