The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T₁ = Lowest absolute temperature, and T₂ = Highest absolute temperature)
T₁ / (T₂ - T₁)
(T₂ - T₁)/T₁
(T₁ - T₂)/T₁
T₂/ (T₂ - T₁)
Correct Answer :
A. T₁ / (T₂ - T₁)
Related Questions
The vertical and uniformly spaced lines on a psychrometric chart indicates
Dry bulb temperature
Wet bulb temperature
Dew point temperature
Specific humidity
The dry bulb temperature lines, on the psychrometric chart are
Vertical and uniformly spaced
Horizontal and uniformly spaced
Horizontal and non-uniformly spaced
Curved lines
The alignment circle is marked on the psychrometric chart at
20°C DBT and 50% RH
26°C DBT and 50% RH
20°C DBT and 60% RH
26°C DBT and 60% RH
Superheating in a refrigeration cycle
Increases C.O.P
Decreases C.O.P
C.O.P remains unaltered
Other factors decide C.O.P
Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system
Strong solution to weak solution
Weak solution to strong solution
Strong solution to ammonia vapour
Ammonia vapours to weak solution
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
Wet 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
Which of the following cycles uses air as the refrigerant?
Ericson
Stirling
Carnot
Bell Coleman
Which of the following refrigerant has the maximum ozone depletion potential in the stratosphere?
Ammonia
Carbon dioxide
Sulphur dioxide
Fluorine
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 value of C.O.P in vapour compression cycle is usually
Always less than unity
Always more than unity
Equal to unity
Any one of the above
The total pressure exerted by the mixture of air and water vapour is equal to the sum of pressures which each constituent would exert, if it occupied the same space by itself. This statement is called
Kinetic theory of gases
Newton's law of gases
Dalton's law of partial pressures
Avogadro's hypothesis
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)
In vapour compression cycle the condition off refrigerant is dry saturated vapour
After passing through the condenser
Before passing through the condenser
After passing through the expansion or throttle valve
Before entering the compressor
Air refrigeration cycle is used in
Commercial refrigerators
Domestic refrigerators
Air-conditioning
Gas liquefaction
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
During heating and humidification, the final relative humidity of air
Can be lower or higher than that of the entering air
Is lower than that of the entering air
Is higher than that of the entering air
None of the above
The leakage in a refrigeration system using Freon is detected by
Halide torch
Sulphur sticks
Soap and water
All of these
The vapour compression refrigerator employs the following cycle
Rankine
Carnot
Reversed Rankine
Reversed Carnot
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.
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 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
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
In a vapour compression cycle, the refrigerant immediately after expansion valve is
Liquid
Sub-cooled liquid
Saturated liquid
Wet vapour
A one tonne refrigerating machine means that
One tonne is the total mass of machine
One tonne refrigerant is used
One tonne of water can be converted into ice
One tonne of ice when melts from and at 0° C in 24 hours, the refrigeration effect is equivalent to 210 kJ/min
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
Which of the following refrigerant has the lowest boiling point?
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
In vapour compression cycle, the condition of refrigerant is high pressure saturated liquid
After passing through the condenser
Before passing through the condenser
After passing through the expansion or throttle valve
Before entering the expansion valve
The comfort conditions in air conditioning are at (where DBT = Dry bulb temperature, and RH = Relative humidity)
25°C DBT and 100% RH
20°C DBT and 80% RH
22°C DBT and 60% RH
25°C DBT and 40% RH
Which of the following refrigerant has the highest freezing point.
Ammonia
Carbon dioxide
Sulphur dioxide
R-12