The temperature of air recorded by a thermometer, when it is not affected by the moisture present in the air, is called
Wet bulb temperature
Dry bulb temperature
Dew point temperature
None of these
Correct Answer :
B. Dry bulb temperature
Related Questions
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 thermal diffusivity for gases is generally __________ those for liquids.
Equal to
Less than
Greater than
None of these
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
In Electrolux refrigerator
Ammonia is absorbed in hydrogen
Ammonia is absorbed in water
Ammonia evaporates in hydrogen
Hydrogen evaporates in ammonia
The cooling system used for supersonic aircrafts and rockets is
Simple air cooling system
Bootstrap air cooling system
Reduced ambient air cooling system
Regenerative air cooling system
The curved lines on a psychrometric chart indicates
Dry bulb temperature
Wet bulb temperature
Dew point temperature
Relative humidity
The moisture in a refrigerant is removed by
Evaporator
Safety relief valve
Dehumidifier
Driers
Moisture in Freon refrigeration system causes
Ineffective refrigeration
High power consumption
Freezing automatic regulating valve
Corrosion of whole system
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)
Critical temperature is the temperature above which
A gas will never liquefy
A gas will immediately liquefy
Water will evaporate
Water will never evaporate
Environmental protection agencies advice against the use of chlorofluorocarbon refrigerants since
These react with water vapour and cause acid rain
These react with plants and cause greenhouse effect
These react with oxygen and cause its depletion
These react with ozone layer
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 evolution of heat of solution takes place in ammonia absorption plant when
Ammonia vapour goes into solution
Ammonia vapour is driven out of solution
Lithium bromide mixes with ammonia
Weak solution mixes with strong solution
Air refrigeration cycle is used in
Commercial refrigerators
Domestic refrigerators
Air-conditioning
Gas liquefaction
The higher temperature in vapour compression cycle occurs at
Receiver
Expansion valve
Evaporator
Compressor discharge
The specific humidity during heating and humidification process.
Remains constant
Increases
Decreases
None of these
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
The humidification process, on the psychrometric chart is shown by
Horizontal line
Vertical line
Inclined line
Curved line
The temperature of air recorded by a thermometer, when its bulb is surrounded by a wet cloth exposed to the air, is called
Wet bulb temperature
Dry bulb temperature
Dew point temperature
None of these
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
The wet bulb depression indicates _________ humidity of the air.
Absolute
Relative
Specific
None of these
Which of the following is not a desirable property of a refrigerant?
High risibility with oil
Low boiling point
Good electrical conductor
Large latent heat
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
In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is
Less than 2 kg
More than or equal to 3.65 kg
More than 10 kg
There is no such consideration
The sensible heat factor during cooling and dehumidification process is given by (where h₁ = Enthalpy of air entering the cooling coil, h₂ = Enthalpy of air leaving the cooling coil, and hA = Enthalpy of air at the end of dehumidification process)
(hA - h2)/ (h1 - h2)
(h2 - hA)/ (h1 - h2)
(h1 - h2)/ (hA - h2)
(hA - h1)/ (h2 - h1)
The atmospheric air at dry bulb temperature of 15°C enters a heating coil maintained at 40°C. The air leaves the heating coil at 25°C. The bypass factor of the heating coil is
0.376
0.4
0.6
0.67
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
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 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
The relative coefficient of performance is
Actual COP/theoretical COP
Theoretical COP/actual COP
Actual COP × theoretical COP
None of these