Test: Laminar Film Condensation


10 Questions MCQ Test Heat Transfer | Test: Laminar Film Condensation


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This mock test of Test: Laminar Film Condensation for Chemical Engineering helps you for every Chemical Engineering entrance exam. This contains 10 Multiple Choice Questions for Chemical Engineering Test: Laminar Film Condensation (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Laminar Film Condensation quiz give you a good mix of easy questions and tough questions. Chemical Engineering students definitely take this Test: Laminar Film Condensation exercise for a better result in the exam. You can find other Test: Laminar Film Condensation extra questions, long questions & short questions for Chemical Engineering on EduRev as well by searching above.
QUESTION: 1

For laminar film condensation on a vertical plate, the velocity distribution at a distance δ from the top edge is given by

Solution:

An equation for the velocity distribution as a function of some distance from the wall surface can be set up by considering the equilibrium between the gravity and viscous forces on an elementary volume of the liquid film.

QUESTION: 2

For laminar film condensation on a vertical plate, the film thickness is given by

Solution:

The film thickness increases as the fourth root of the distance down the surface.

QUESTION: 3

For laminar film condensation on a vertical plate, the mass flow rate of the condensate per unit depth of the film at any position x is given by

Solution:

Mass flow rate = mean flow velocity * flow area * density.

QUESTION: 4

For laminar film condensation on a vertical plate, the gravitational acceleration g is replaced by

Where, α is the inclination angle with the horizontal

Solution:

It is replaced by sin α.

QUESTION: 5

For laminar film condensation on a vertical plate, the local heat transfer coefficient at the lower edge of the plate is given by

Solution:

The rate of condensation heat transfer is higher at the upper end of the plate than at the lower end.

QUESTION: 6

Mark the wrong statement with respect to laminar flow condensation on a vertical plate

Solution:

The average heat transfer coefficient is 4/3 of the local heat transfer coefficient at the lower edge of the plate.

QUESTION: 7

A plate condenser of dimensions l * b has been designed to be kept with side l in the vertical position. However due to oversight during erection and installation, it was fixed with side b vertical. How would this affect the heat transfer? Assume laminar conditions and same thermos-physical properties and take b = l/2

Solution:

1 = 0.943 [k 3 p 2 g h f g/δ l (t sat – t s)] 0.25, h2 = 0.943 [k 3 p 2 g h f g/δ b (t sat – t s)] 0.25. So, h 1/h = 0.8409.

QUESTION: 8

Determine the length of a 25 cm outer diameter tube if the condensate formed on the surface of the tube is to be same whether it is kept vertical or horizontal

Solution:

v = 0.943 [k 3 p 2 g h f g/δ l (t sat – t s)] 0.25, h H = 0.943 [k 3 p 2 g h f g/δ d (t sat– t s)] 0.25, l/d = 2.86.

QUESTION: 9

The critical Reynolds number for transition from laminar to turbulent film condensation is

Solution:

This should be 1800 for perfect transition from laminar to turbulent film condensation.

QUESTION: 10

Which of the following is a wrong statement in the context of convective heat transfer coefficient in laminar film condensation?The heat transfer coefficient varies as

Solution:

h = 0.943 [k 3 p 2 g h f g/δ l (t sat – t s)] 0.25. Further the heat transfer coefficient varies as ¼ power of acceleration due to gravity.

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