Critical pressure of a liquid is the pressure
Above which liquid will remain liquid
Above which liquid becomes gas
Above which liquid becomes vapour
Above which liquid becomes solid
Correct Answer :
A. Above which liquid will remain liquid
Related Questions
Mass flow ratio of NH₃ in comparison to Freon12 for same refrigeration load and same temperature limits is of the order of
1 : 1
1 : 9
9 : 1
1 : 3
As relative humidity decreases, the dew point temperature will be ________ wet bulb temperature.
Same as
Lower than
Higher than
None of these
Absorption system normally uses the following refrigerant
Freon-11
Freon-22
CO2
Ammonia
For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of
Copper
Aluminium
Steel
Brass
Vertical lines on pressure-enthalpy chart show constant
Pressure lines
Temperature lines
Total heat lines
Entropy lines
In a vapour absorption refrigeration system, the compressor of the vapour compression system is replaced by
Liquid pump
Generator
Absorber and generator
Absorber, generator and liquid pump
The minimum temperature to which water can be cooled in a cooling tower is
Dew point temperature of air
Wet bulb temperature of air
Dry bulb temperature of air
Ambient air temperature
Air conditioning means
Cooling
Heating
Dehumidifying
All of these
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
Oil separator in a refrigeration cycle is installed
Before compressor
Between compressor and condenser
Between condenser and evaporator
Between condenser and expansion valve
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
In a vapour compression system, the condition of refrigerant before entering the expansion or throttle valve is
High pressure saturated liquid
Wet vapour
Very wet vapour
Dry vapour
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 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
In order to collect liquid refrigerant and to prevent it from going to a ________, a device known as accumulator is used at the suction of compressor.
Compressor
Condenser
Expansion valve
Evaporator
A refrigeration system
Removes heat from a low temperature body and delivers it to a high temperature body
Removes heat from a high temperature body and delivers it to a low temperature body
Rejects energy to a low temperature body
None of the above
Most thermostatic expansion valves are set for a superheat of
5°C
10°C
15°C
20°C
In vapour compression cycle the condition of refrigerant is superheated vapour
After passing through the condenser
Before passing through the condenser
After passing through the expansion or throttle valve
Before entering the expansion valve
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 COP of a vapour compression plant in comparison to vapour absorption plant is
More
Less
Same
More/less depending on size of plant
Highest pressure encountered in a refrigeration system should be
Critical pressure of refrigerant
Much below critical pressure
Much above critical pressure
Near critical pressure
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
Ammonia is
Non-toxic
Non-inflammable
Toxic and non-inflammable
Highly toxic and inflammable
When the lower temperature of a refrigerating machine is fixed, then the coefficient of performance can be improved by
Operating the machine at higher speeds
Operating the machine at lower speeds
Raising the higher temperature
Lowering the higher temperature
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
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
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 capillary tube, as an expansion device, is used in
Domestic refrigerators
Water coolers
Room air conditioners
All of these
The boiling point of ammonia is
100°C
50°C
33.3°C
0°C
The bank of tubes at the back of domestic refrigerator is
Condenser tubes
Evaporator tubes
Refrigerant cooling tubes
Capillary tubes