Asymptotic conditions is reached, when for a fluid flowing in laminar flow through a long tube

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 a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is

A

Nu = 0.023 Re^0.8.Pr^0.4

B

Nu = $$\frac{\pi }{2}$$ Gz

C

Nu = $$\frac{2}{\pi }$$ Gz

D

Nu = 2 Gz^0.5

The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are

A

Re.Gz

B

Nu, Pr

C

Nu, Pr, Re

D

Nu, Gz

Transition from laminar flow to turbulent flow in fluid flow through a pipe does not depend upon the

A

Length of the pipe

B

Diameter of the pipe

C

Density of the fluid

D

Velocity of the fluid

Experimental study of laminar fluid flow through a circular tube was conducted by

A

Reynolds

B

Hagen and Poiseuille

C

Pascal

D

Blake-Plummer

The velocity profile for a Bingham plastic fluid flowing (under laminar conditions) in a pipe is

A

Parabolic

B

Flat

C

Flat near the wall and parabolic in the middle

D

Parabolic near the wall and flat in the middle

A Newtonion liquid (ρ = density, μ = viscosity) is flowing with velocity v in a tube of diameter 'D'. Let Δp be the pressure drop across the length 'L'. For a laminar flow, Δp is proportional to

A

L ρv²/D

B

L μ;V/D²

C

D ρv²/L

D

Μ V/L

Heat exchangers operating, when the asymptotic range is reached,

A

Provide very large heat transfer co-efficient

B

Results in making part of the heating surface inactive

C

Results in abruptly increased velocity

D

None of these

Applying a pressure drop across a capillary results in a volumetric flow rate 'Q' under laminar flow conditions. The flow rate for the same pressure drop, in a capillary of the same length but half the radius is

A

$$\frac{{\text{Q}}}{2}$$

B

$$\frac{{\text{Q}}}{4}$$

C

$$\frac{{\text{Q}}}{8}$$

D

$$\frac{{\text{Q}}}{{16}}$$

The ratio of average fluid velocity to the maximum velocity in case of laminar flow of a Newtonion fluid in a circular pipe is

A

0.5

B

1

C

2

D

0.66

Asymptotic conditions is reached, when for a fluid flowing in laminar flow through a long tube

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