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 2 of 8

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Q11.
Glass spheres of 2 mm radius and at 500 degree Celsius are to be cooled by exposing them to an air stream at 25 degree Celsius. Find maximum value of convective coefficient that is permissible. Assume the following property values
Density = 2250 kg/m³
Specific heat = 850 J/kg K
Conductivity = 1.5 W/m K

a.

245 W/m²K

b.

235 W/m²K

c.

225 W/m²K

d.

215 W/m²K

Discuss
Answer: (c).225 W/m²K
Q12.
The transient response of a solid can be determined by the equation. (Where, P is density, V is volume, c is specific heat and A is area)

a.

– 4 p V c = h A (t – t0)

b.

– 3 p V c = h A (t – t0)

c.

– 2 p V c = h A (t – t0)

d.

– p V c = h A (t – t0)

Discuss
Answer: (d).– p V c = h A (t – t0)
Q13.
A 2 cm thick steel slab heated to 525 degree Celsius is held in air stream having a mean temperature of 25 degree Celsius. Estimate the time interval when the slab temperature would not depart from the mean value of 25 degree Celsius by more than 0.5 degree Celsius at any point in the slab. The steel plate has the following thermal physical properties
Density = 7950 kg/m³
C P = 455 J/kg K
K = 46 W/m K

a.

6548 s

b.

6941 s

c.

4876 s

d.

8760 s

Discuss
Answer: (b).6941 s
Q14.
“The response of a thermocouple is defined as the time required for the thermocouple to reach the surrounding temperature when it is exposed to it”. Choose the correct answer

a.

True

b.

False

c.

May be

d.

Can't say

Discuss
Answer: (b).False
Q15.
The sensitivity of thermocouple is defined as the time required by thermocouple to reach how much percentage of its steady state values?

a.

43.3

b.

53.2

c.

63.3

d.

73.3

Discuss
Answer: (c).63.3
Q16.
The response time for different sizes and materials of thermocouple wires usually lie between

a.

0.04 to 2.5 seconds

b.

0.06 to 1.2 seconds

c.

0.02 to 0.04 seconds

d.

2.4 to 9.4 seconds

Discuss
Answer: (a).0.04 to 2.5 seconds
Q17.
A thermocouple junction of spherical form is to be used to measure the temperature of the gas stream. The junction is at 20 degree Celsius and is placed in a gas stream which is at 200 degree Celsius. Make calculations for time required by the thermocouple to reach 197 degree Celsius temperature. Assume the thermos-physical properties as given below
k = 20 W/ m K

h = 350 W/m² K

c = 0.4 k J/kg K

p = 8000 kg/m³

a.

1.094 seconds

b.

2.094 seconds

c.

3.094 seconds

d.

4.094 seconds

Discuss
Answer: (d).4.094 seconds
Q18.
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
Q19.
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
Q20.
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
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