Heat Exchangers and Mass Transfer MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on Heat Exchangers and Mass Transfer, a fundamental topic in the field of Heat Transfer. Whether you're preparing for competitive exams, honing your problem-solving skills, or simply looking to enhance your abilities in this field, our Heat Exchangers and Mass Transfer MCQs are designed to help you grasp the core concepts and excel in solving problems.

In this section, you'll find a wide range of Heat Exchangers and Mass Transfer mcq questions that explore various aspects of Heat Exchangers and Mass Transfer problems. Each MCQ is crafted to challenge your understanding of Heat Exchangers and Mass Transfer principles, enabling you to refine your problem-solving techniques. Whether you're a student aiming to ace Heat Transfer tests, a job seeker preparing for interviews, or someone simply interested in sharpening their skills, our Heat Exchangers and Mass Transfer MCQs are your pathway to success in mastering this essential Heat Transfer topic.

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Heat Exchangers and Mass Transfer MCQs | Page 6 of 7

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Q51.
E – NTU method is particularly useful in thermal design of heat exchangers when

a.

Inlet temperature of the fluid streams are not known as a priori

b.

The outlet temperatures of the hot fluid streams is known but that of cold fluid stream is not known as a priori

c.

The outlet temperatures of the fluid streams is known as a priori

d.

The outlet temperatures of the fluid streams are not known as a priori

Discuss
Answer: (d).The outlet temperatures of the fluid streams are not known as a priori
Q52.
The engine oil at 150 degree Celsius is cooled to 80 degree Celsius in a parallel flow heat exchanger by water entering at 25 degree Celsius and leaving at 60 degree Celsius. Estimate the number of transfer units

a.

1.221

b.

2.221

c.

3.221

d.

4.221

Discuss
Answer: (a).1.221
Q53.
In a surface condenser, the water flowing through a series of tubes at the rate of 200 kg/hr is heated from 15 degree Celsius to 75 degree Celsius. The steam condenses on the outside surface of tubes at atmospheric pressure and the overall heat transfer coefficient is estimated at 860 k J/m² hr degree. Find the number of transfer units of the heat exchanger. At the condensing pressure, stream has saturation temperature 0f 100 degree Celsius and the latent heat of vaporization is 2160 k J/kg. Further, the steam is initially just saturated and the condensate leaves the exchanger without sub-cooling i.e. only latent heat of condensing steam is transferred to water. Take specific heat of water as 4 k J/kg K

a.

3.224

b.

2.224

c.

1.224

d.

0.224

Discuss
Answer: (c).1.224
Q54.
NTU is a number of transfer units, dimensionless parameter defined as

a.

U A/C MIN

b.

2 U A/C MIN

c.

3 U A/C MIN

d.

4 U A/C MIN

Discuss
Answer: (a).U A/C MIN
Q55.
When two fluids of the heat exchanger are separated by a plane wall, the thermal resistance comprises
(i) Convection resistance due to the fluid film at the inside surface
(ii) Conduction resistance
(iii) Convection resistance due to the fluid film at the outside surface
Identify the correct option

a.

1 and 2

b.

1, 2 and 3

c.

2 and 3

d.

1 and 3

Discuss
Answer: (b).1, 2 and 3
Q56.
Figure represents the block diagram of a heat exchanger. There were some aspects in the design and performance analysis of a heat exchanger. Identify the correct one

a.

The coolant picks up heat = m h c c (t c1 – t c2)

b.

The hot fluid gives up heat = m h c h (t h1 – t c2)

c.

The coolant picks up heat = m c c h (t h1 – t c2)

d.

The hot fluid gives up heat = m h c h (t h1 – t h2)

Discuss
Answer: (d).The hot fluid gives up heat = m h c h (t h1 – t h2)
Q57.
The heat loss from unpainted aluminum side of a house has been calculated on the presumption that overall coefficient of heat transfer is 5 W/m² K. Later, it was discovered that the air pollution levels are such that fouling factor on this side is of the order of 0.0005 m² K/W. Find overall heat transfer coefficient of dirty side

a.

2.9875 W/m² K

b.

3.9875 W/m² K

c.

4.9875 W/m² K

d.

5.9875 W/m² K

Discuss
Answer: (c).4.9875 W/m² K
Q58.
What is the value of fouling factor for engine exhaust?

a.

0.002 m² K/W

b.

0.003 m² K/W

c.

0.004 m² K/W

d.

0.005 m² K/W

Discuss
Answer: (a).0.002 m² K/W
Q59.
What is the value of fouling factor for industrial liquids?

a.

0.0004 m² K/W

b.

0.0003 m² K/W

c.

0.0002 m² K/W

d.

0.0001 m² K/W

Discuss
Answer: (c).0.0002 m² K/W
Q60.
After being in service for a period of six months, a heat exchanger transforms 10% less heat than it does what new. Determine the effective fouling factor in terms of its clean overall heat transfer coefficient. It may be presumed that the heat exchanger operates between the same temperature differentials and that there is no change in the effective surface area due to scale build up

a.

0.13/ U CLEAN

b.

0.11/ U CLEAN

c.

0.09/ U CLEAN

d.

0.07/ U CLEAN

Discuss
Answer: (b).0.11/ U CLEAN
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