Related Questions

For pipes, turbulent flow occurs when Reynolds number is
A Less than 2000
B Between 2000 and 4000
C More than 4000
D Less than 4000
In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said to have the same hydraulic roughness, when they have equal values of
A Relative roughness
B Absolute roughness
C Friction co-efficient for flows at equal Reynold number
D All of the above
A tank is fitted with 8 pipes, some of them that fill the tank and others that are waste pipe meant to those that empty the tank can empty it in 6 hours. If all the pipes are kept open when the tank is full, it will take exactly 6 hours for the tank to empty. How many of these are these are fill pipes?
A 2
B 4
C 6
D 5
For pipes, laminar flow occurs when Reynolds number is
A Less than 2000
B Between 2000 and 4000
C More than 4000
D Less than 4000
In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by
A Convection
B Radiation
C Conduction
D Both convection and conduction
For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus-Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of
A 1
B 1.74
C 6.1
D 37
When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is
A Free convection
B Entry length problem in laminar forced conduction (developing thermal boundary layer)
C Mixed convection (both free and forced)
D Forced convection
According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, D = molecular diffusivity)
A D
B D2
C D0.5
D $$\frac{1}{{\text{D}}}$$
Overall mass transfer co-efficient in case of absorption of __________ in water is based on the gas film co-efficient only, as the mass transfer process is gas film (phase) controlling.
A CO2
B SO2
C NH3
D None of these
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

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