Transient Heat MCQs

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

Note: Each of the following question comes with multiple answer choices. Select the most appropriate option and test your understanding of Transient Heat. You can click on an option to test your knowledge before viewing the solution for a MCQ. Happy learning!

So, are you ready to put your Transient Heat knowledge to the test? Let's get started with our carefully curated MCQs!

Transient Heat MCQs | Page 7 of 8

Discover more Topics under Heat Transfer

Q61.
When the surface temperature variation inside a solid are periodic in nature, the profile of temperature variation with time may assume

a.

Triangular

b.

Linear

c.

Parabolic

d.

Hyperbolic

Discuss
Answer: (a).Triangular
Q62.
The surface temperature oscillates about the mean temperature level in accordance with the relation

a.

ฮฑ S,T โ€“ ฮฑ S,A = 2 sin (2 ฯ€ n T)

b.

ฮฑ S,T โ€“ ฮฑ S,A = 5 sin (2 ฯ€ n T)

c.

ฮฑ S,T โ€“ ฮฑ S,A = sin (2 ฯ€ n T)

d.

ฮฑ S,T โ€“ ฮฑ S,A = 3 sin (2 ฯ€ n T)

Discuss
Answer: (c).ฮฑ S,T โ€“ ฮฑ S,A = sin (2 ฯ€ n T)
Q63.
The temperature variation of a thick brick wall during periodic heating or cooling follows a sinusoidal waveform. During a period of 24 hours, the surface temperature ranges from 25 degree Celsius to 75 degree Celsius. Workout the time lag of the temperature wave corresponding to a point located at 25 cm from the wall surface. Thermo-physical properties of the wall material are; thermal conductivity = 0.62 W/m K; specific heat = 450 J/kg K and density = 1620 kg/m³

a.

3.980 hour

b.

6.245 hour

c.

2.648 hour

d.

3.850 hour

Discuss
Answer: (b).6.245 hour
Q64.
A single cylinder 2-stroke engine operates at 1500 rpm. Calculate the depth where the temperature wave due to variation in cylinder is damped to 1% of its surface value. For the cylinder material, thermal diffusivity = 0.042 m²/hr

a.

0.1996 cm

b.

0.3887 cm

c.

0.2774 cm

d.

0.1775 cm

Discuss
Answer: (d).0.1775 cm
Q65.
The temperature distribution at a certain time instant through a 50 cm thick wall is prescribed by the relation

T = 300 โ€“ 500 x โ€“ 100 x² + 140x³

Where temperature t is in degree Celsius and the distance x in meters has been measured from the hot surface. If thermal conductivity of the wall material is 20 k J/m hr degree, calculate the heat energy stored per unit area of the wall

a.

4100 k J/hr

b.

4200 k J/hr

c.

4300 k J/hr

d.

4400 k J/hr

Discuss
Answer: (a).4100 k J/hr
Q66.
A large plane wall, 40 cm thick and 8 m² area, is heated from one side and temperature distribution at a certain time instant is approximately prescribed by the relation:

T = 80 โ€“ 60 x +12 x² + 25 x³ โ€“ 20 xโด

Where temperature t is in degree Celsius and the distance x in meters. Make calculations for heat energy stored in the wall in unit time.

For wall material:
Thermal conductivity = 6 W/m K and thermal diffusivity = 0.02 m²/hr

a.

870.4 W

b.

345.6 W

c.

791.04 W

d.

238.5 W

Discuss
Answer: (c).791.04 W
Q67.
Fourier number is given by

a.

ฮฑ T/LC²

b.

2 ฮฑ T/LC²

c.

3 ฮฑ T/LC²

d.

4 ฮฑ T/LC²

Discuss
Answer: (a).ฮฑ T/LC²
Q68.
Identify the correct relation between Biot number and Fourier number

a.

4 b T = B I F 0

b.

2 b T = B I F 0

c.

3 b T = B I F 0

d.

b T = B I F 0

Discuss
Answer: (d).b T = B I F 0
Q69.
A water line is buried underground in dry soil that has an assumed initial temperature of 4.5 degree Celsius. The pipe may have no flow through it for long period of time, yet it will not be drained in order that no freezing occurs, the pipe must be kept at a temperature not lower than 0 degree Celsius. The pipe is to be designed for a 30 hour period at the beginning of which the soil surface temperature suddenly drops to โ€“ 17 degree Celsius. Workout the minimum earth covering needed above the water pipe so as to prevent the possibility of freezing during 36 hour cold spell. The soil in which the pipe is buried has the following properties

Density = 640 kg/m³
Specific heat = 1843J/kg degree
Thermal conductivity = 0.345 W/m degree

a.

0.25 m

b.

0.35 m

c.

0.45 m

d.

0.55 m

Discuss
Answer: (b).0.35 m
Q70.
At a certain time instant, the temperature distribution in a long cylindrical fire tube can be represented approximately by the relation

T = 650 + 800 r โ€“ 4250 r²

Where temperature t is in degree Celsius and radius r is in meter. Find the rate of heat flow such that the tube measures: inside radius 25 cm, outside radius 40 cm and length 1.5 m.

For the tube material

K = 5.5 W/m K

ฮฑ = 0.004 m²/hr

a.

3.672 * 10 8 W

b.

3.672 * 10 2 W

c.

3.672 * 10 5 W

d.

โ€“ 3.672 * 10 5 W

Discuss
Answer: (d).โ€“ 3.672 * 10 5 W
Page 7 of 8