Related Questions

In case of cooling towers, the ratio of the rates of heat and mass transfer is indicated by the __________ number.
A Lewis
B Grashoff
C Sherwood
D None of these
Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the
A Surrounding temperature
B Average temperature of the fin
C Temperature of the fin end
D Constant temperature equal to that of the base
In actual operation of a bubble cap distillation tower, the __________ at the bottom of the tower is more than that at the top of the tower.
A Molal flow rate of vapour
B Vapour molecular weight
C Pressure and temperature
D All of the above
The scales form in heat exchanges after a period of operation and provide additional resistance to heat transfer with some heat transfer coefficient . The reciprocal of this scale heat transfer coefficient is called .
A scaling factor
B forming factor
C resisting factor
D fouling factor
Noise produced by cooling fans (employed in air cooled heat exchangers or cooling tower) is mainly caused due to the turbulence created by blade passage through air. It can be reduced by use of a slower fan
A With greater number of blades
B Of increased diameter
C Both A & B
D Neither A nor B
A natural draft cooling tower is filled with wooden grids, which covers about __________ percent of the tower height.
A 10-15
B 30-40
C 70-80
D 90-100
A packed tower compared to a plate tower for a particular mass transfer operation
A Incurs smaller pressure drop
B Allows installation of cooling coils
C Is less costly when built in large sizes/diameters
D Is more suitable, if suspended solids are present in fluid streams
Minimum temperature upto which water can be theoretically cooled down in the cooling tower by evaporative cooling is equal to the __________ temperature of air.
A Wet bulb
B Dry bulb
C Saturation
D Dew point
For experimental determination of mass transfer co-efficient by wetted wall tower, the mass transfer area is
A Calculated
B Unknown
C Known
D Not required
The cooling effect in a cooling tower can not be increased by
A Increasing the air velocity over the wet surfaces
B Reducing the humidity of entering air
C Lowering the barometric pressure
D None of these

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