Which of the following statement is correct?
The constant enthalpy lines are also constant wet bulb temperature lines.
The wet bulb and dry bulb temperature are equal at saturation condition.
The wet bulb temperature is a measure of enthalpy of moist air.
All of the above
Correct Answer :
D. All of the above
Related Questions
Domestic refrigerator working on vapour compression cycle uses the following type of expansion device
Electrically operated throttling valve
Manually operated valve
Thermostatic valve
Capillary tube
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
The wet bulb temperature during sensible cooling of air
Remains constant
Increases
Decreases
None of these
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
Aqua ammonia is used as refrigerant in the following type of refrigeration system
Compression
Direct
Indirect
Absorption
Which of the following refrigerant has the highest freezing point.
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
In a refrigeration cycle, the flow of refrigerant is controlled by
Compressor
Condenser
Evaporator
Expansion valve
The refrigerant for a refrigerator should have
High sensible heat
High total heat
High latent heat
Low latent heat
The capillary tube is not used in large capacity refrigeration systems because
Cost is too high
Capacity control is not possible
It is made of copper
Required pressure drop cannot be achieved
The freezing point of R-12 is
-86.6°C
-95.2°C
-107.7°C
-135.8°C
The central air conditioning system has ________ overall efficiency as compared to individual systems.
Same
Lower
Higher
None of these
One ton of the refrigeration is
The standard unit used in refrigeration problems
The cooling effect produced by melting 1 ton of ice
The refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours
The refrigeration effect to produce 1 ton of ice at NTP conditions
The undesirable property of a refrigerant is
Non-toxic
Non-flammable
Non-explosive
High boiling point
The condition of refrigerant after passing through the expansion or throttle valve, in a vapour compression system is
High pressure saturated liquid
Wet vapour
Very wet vapour
Dry vapour
The C.O.P. of a heat pump working on a reversed Carnot cycle is
T₁/(T₂ - T₁)
(T₂ - T₁)/T₁
(T₁ - T₂)/T₁
T₂/(T₂ - T₁)
Refrigeration in aeroplanes usually employs the following refrigerant
CO2
Freon-11
Freon-22
Air
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
Air conditioning means
Cooling
Heating
Dehumidifying
All of these
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)
Ammonia absorption refrigeration cycle requires
Very little work input
Maximum work input
Nearly same work input as for vapour compression cycle
Zero work input
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)
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
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
Most of the domestic refrigerators work on the following refrigeration system
Vapour compression
Vapour absorption
Carnot cycle
Electrolux refrigerator
Condensing temperature in a refrigerator is the temperature
Of cooling medium
Of freezing zone
Of evaporator
At which refrigerant gas becomes liquid
A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigerating machine with all other conditions unchanged, the coefficient of performance will be
1.33
2.33
3.33
4.33
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 human body feels comfortable when the heat stored in the body is
Positive
Negative
Zero
None 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
In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be
High, of the order of 25°
As low as possible (3 to 11°C)
Zero
Any value