Chemical Engineering - Heat Transfer

1. 

Reason for operating an evaporator in multiple effect is to secure

A. increased steam economy.
B. decreased steam consumption.
C. both (a) and (b).
D. increased capacity.

Answer: Option C

Explanation:

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2. 

In a cooling tower, water becomes cool by

A. loosing sensible heat.
B. heat transfer to surroundings.
C. vaporisation due to heat loss to air.
D. loosing latent heat.

Answer: Option A

Explanation:

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3. 

In Fourier's law, the proportionality constant is called the

A. heat transfer co-efficient
B. thermal diffusivity
C. thermal conductivity
D. Stefan-Boltzman constant

Answer: Option C

Explanation:

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4. 

The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation.

A. greater than
B. lower than
C. is same as
D. half

Answer: Option B

Explanation:

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5. 

Pick out the wrong statement.

A. Bubble size increases with the dynamic viscosity of the liquid in case of nucleate pool boiling.
B. Thermal conductivity of a dry material is more than that of the damp material.
C. Ratio of its capacity to economy equals the steam consumption in kg/hr in an evaporator.
D. Vaporisation of organic substances in evaporator mostly causes foam formation.

Answer: Option B

Explanation:

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