Heat Transfer From Extended Surfaces MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on Heat Transfer From Extended Surfaces, 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 Transfer From Extended Surfaces 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 Transfer From Extended Surfaces mcq questions that explore various aspects of Heat Transfer From Extended Surfaces problems. Each MCQ is crafted to challenge your understanding of Heat Transfer From Extended Surfaces 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 Transfer From Extended Surfaces MCQs are your pathway to success in mastering this essential Heat Transfer topic.

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Heat Transfer From Extended Surfaces MCQs | Page 3 of 8

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Q21.
Which one is true regarding rectangular fin?

a.

A C = b ฮด and P = 2(b + ฮด)

b.

A C = 2 b ฮด and P = 2(b + ฮด)

c.

A C = 3 b ฮด and P = 2(b + ฮด)

d.

A C = 4 b ฮด and P = 2(b + ฮด)

Discuss
Answer: (a).A C = b ฮด and P = 2(b + ฮด)
Q22.
Analysis of heat flow from the finned surface is made with the following assumptions
(i) Uniform heat transfer coefficient, h over the entire fin surface
(ii) No heat generation within the fin generation
(iii) Homogenous material
Identify the correct option

a.

i only

b.

i and ii only

c.

i, ii and iii

d.

ii only

Discuss
Answer: (c).i, ii and iii
Q23.
If heat conducted into the element at plane x is Q X = โ€“ k A C (d t/d x) X. Then heat conducted out of the element at plane (x + d x) is

a.

โ€“ 2k A C d/d x (t + d t/d x (d x))

b.

โ€“ k A C d/d x (t + d t/d x (d x))

c.

โ€“ 3k A C d/d x (t + d t/d x (d x))

d.

โ€“ 4k A C d/d x (t + d t/d x (d x))

Discuss
Answer: (b).โ€“ k A C d/d x (t + d t/d x (d x))
Q24.
A heating unit is made in the form of a vertical tube of 50 mm outside diameter and 1.2 m height. The tube is fitted with 20 steel fins of rectangular section with height 40 mm and thickness 2.5 mm. The temperature at the base of fin is 75 degree Celsius, the surrounding air temperature is 20 degree Celsius and the heat transfer coefficient between the fin as well as the tube surface and the surrounding air is 9.5 W/m² K. If thermal conductivity of the fin material is 55 W/m K, find the amount of heat transferred from the tube without fin

a.

98.44 W

b.

88.44 W

c.

78.44 W

d.

68.44 W

Discuss
Answer: (a).98.44 W
Q25.
For steady flow of heat along a rod, the general equation is
d²ฮฑ/dx² โ€“ m² ฮฑ = 0
The value of constant m is

a.

(h P/k A C)

b.

(h P/k A C)^3/2

c.

(h P/k A C)^1/2

d.

(h P/k A C)^2

Discuss
Answer: (c).(h P/k A C)^1/2
Q26.
In convection from the tip, we introduced a factor known as

a.

Fin length

b.

Correction length

c.

No fin length

d.

Radial length

Discuss
Answer: (b).Correction length
Q27.
Find the value of corrected length for rectangular fin?
Where, b is width and t is length of the fin

a.

L C = L + b t/2 (b + t)

b.

L C = L + b t/ (b + t)

c.

L C = L + 2 (b + t)

d.

L C = L + b t

Discuss
Answer: (a).L C = L + b t/2 (b + t)
Q28.
Which one is true for the spine?

a.

A C = ฯ€ d²/4 and P = 4 ฯ€ d

b.

A C = ฯ€ d²/4 and P = 3 ฯ€ d

c.

A C = ฯ€ d²/4 and P = ฯ€ d

d.

A C = ฯ€ d²/4 and P = 2 ฯ€ d

Discuss
Answer: (c).A C = ฯ€ d²/4 and P = ฯ€ d
Q29.
In convection from the tip what is the value of correction length?

a.

L C = A C/P

b.

L C = L + A C

c.

L C = L + P

d.

L C = L + A C/P

Discuss
Answer: (d).L C = L + A C/P
Q30.
Let us assume there are two pieces of copper wire 0.1625 cm in diameter with a device that melts it at 195 degree Celsius. The wires are positioned vertically in air at 24 degree Celsius and the heat transfer coefficient of the wire is 17 W/ square m K. Let us say k = 335W/m K i.e. of wire. Find out the energy input?

a.

1.234W

b.

2.652W

c.

4.562W

d.

9.435W

Discuss
Answer: (b).2.652W
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