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 5 of 8

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Q41.
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
Q42.
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)
Q43.
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
Q44.
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
Q45.
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
Q46.
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
Q47.
An average convective heat transfer coefficient for flow of air over a sphere has been measured by observing the temperature-time history of a 12 mm diameter copper sphere (density = 9000 kg/m³ and c = 0.4 k J/kg K) exposed to air at 30 degree Celsius. The temperature of the sphere was measured by two thermocouples one located at the center and the other near the surface. The initial temperature of the ball was 75 degree Celsius and it decreased by 10 degree Celsius in 1.2 minutes. Find the heat transfer coefficient

a.

27.46 W/m² K

b.

21.76 W/m² K

c.

29.37 W/m² K

d.

25.13 W/m² K

Discuss
Answer: (d).25.13 W/m² K
Q48.
Transient condition means

a.

Conduction when temperature at a point varies with time

b.

Very little heat transfer

c.

Heat transfer with a very little temperature difference

d.

Heat transfer for a short time

Discuss
Answer: (a).Conduction when temperature at a point varies with time
Q49.
Which of the following is not correct in a transient flow process?

a.

The state of matter inside the control volume varies with time

b.

There can be work and heat interactions across the control volume

c.

There is no accumulation of energy inside the control volume

d.

The rate of inflow and outflow of mass are different

Discuss
Answer: (c).There is no accumulation of energy inside the control volume
Q50.
A cylindrical stainless steel (k = 25 W/m K) ingot, 10 cm in diameter and 25 cm long, passes through a heat treatment furnace which is 5 meter in length. The initial ingot temperature is 90 degree Celsius, the furnace gas is at 1260 degree Celsius and the combined radiant and convective surface coefficient is 100 W/m² K. Determine the maximum speed with which the ingot moves through the furnace if it must attain 830 degree Celsius temperature. Take thermal diffusivity as 0.45 * 10¯โต m²/s

a.

. 000116 m/s

b.

.000216 m/s

c.

. 000316 m/s

d.

. 000416 m/s

Discuss
Answer: (b)..000216 m/s
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