Heat Transfer (3151909) MCQs

MCQs of Two-Phase Heat Transfer

Showing 1 to 10 out of 11 Questions
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1.

Dropwise condensation usually occurs on 

(a)

glazed surface 
(b)

smooth surface
(c)

oily surface
(d)

coated surface
Answer:

Option (c)

2.

With an increase in excess temperature, the heat flux in boiling

(a)

increases continuously
(b)

decreases and then increases
(c)

decreases, and then increases and again decreases
(d)

increases then decrease and again increases
Answer:

Option (d)

3.

The excess temperature range 50°C<∆T<200°C is indicative of the region of

(a)

interface evaporation 
(b)

nuclear boiling 
(c)

partial film boiling
(d)

stable film boiling
Answer:

Option (c)

4.

Leiden frost effect is associated with 

(a)

evaporation of a solution
(b)

boiling of liquid on a hot surface
(c)

exchange of heat between two fluids
(d)

condensation of vapour on a cold surface
Answer:

Option (b)

5.

Heat flux increases with temperature excess beyond the Leiden frost point due to

(a)

the occurrence of subcooled boiling 
(b)

promotion of nucleate boiling 
(c)

radiation effect becomes predominant
(d)

vapour space becomes large
Answer:

Option (c)

6.

In the nucleate pool boiling, the heat flux depends on 

(a)

the material of the surface only 
(b)

material and roughness of the surface
(c)

liquid properties, the material of the surface
(d)

liquid properties material, and condition of the surface
Answer:

Option (d)

7.

Which of the following statement is wrong?

(a)

Film boiling is always desired.
(b)

Drop-wise condensation occurs on a contaminated surface.
(c)

Above a critical temperature of boiling, metal could burn-out.
(d)

Fins effectiveness could be increased by using high thermal conductivity materials.
Answer:

Option (a)

8.

The convective coefficients for boiling and condensation usually lie in the range

(a)

30-300 W/m2K
(b)

60-3000 W/m2K
(c)

300-10000 W/m2K
(d)

2500-10000 W/m2K
Answer:

Option (d)

9.

Milk spills over when it is boiled in an open vessel. The boiling of milk at this instant is referred to as 

(a)

interface evaporation
(b)

sub-cooled boiling
(c)

film boiling
(d)

saturated nucleate boiling
Answer:

Option (c)

10.

In spite of large heat transfer coefficients in boiling liquids, fins are used advantageously when the entire surface is exposed to

(a)

film boiling
(b)

transition boiling
(c)

nucleate boiling
(d)

all modes of boiling
Answer:

Option (d)

Showing 1 to 10 out of 11 Questions
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