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 4 of 8

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Q31.
In the lumped system parameter model, the variation of temperature with time is

a.

Linear

b.

Exponential

c.

Sinusoidal

d.

Cube

Discuss
Answer: (b).Exponential
Q32.
Which of the following dimensionless number gives an indication of the ratio of internal (conduction) resistance to the surface (convective) resistance?

a.

Biot number

b.

Fourier number

c.

Stanton number

d.

Nusselt number

Discuss
Answer: (a).Biot number
Q33.
An egg with mean diameter of 4 cm and initially at 25 degree Celsius is placed in an open boiling water container for 4 minutes and found to be boiled at a particular level. For how long should a similar egg boil at the same level, when refrigerator temperature is 5 degree Celsius? Use lumped parameter theory and assume following properties of egg

k = 12 W/m K

h = 125 W/m² K

c = 2 k J/kg K

p = 1250 kg/m³

a.

251.49 seconds

b.

261.49 seconds

c.

271.49 seconds

d.

281.49 seconds

Discuss
Answer: (c).271.49 seconds
Q34.
A person is found dead at 5 pm in a room whose temperature is 20 degree Celsius. The temperature of body is measured to be 25 degree Celsius, when found and heat transfer coefficient is estimated to be 8 W/m² K. Modeling the body as a 30 cm diameter, 1.7 cm long cylinder. Estimate the time of death of person.

a.

13.55 seconds

b.

12.55 seconds

c.

11.55 seconds

d.

10.55 seconds

Discuss
Answer: (d).10.55 seconds
Q35.
The following data pertains to the junction of a thermocouple wire used to measure the temperature of the gas stream.

Density = 8500 kg/m³, specific heat = 325 J/kg K, thermal conductivity = 40 W/m K and the heat transfer coefficient between the junction and gas = 215 W/m² K.

If thermocouple junction can be approximated as 1 mm diameter sphere, determine how long it will take for the thermocouple to read 99% of the initial temperature difference.

a.

9.86 seconds

b.

8.86 seconds

c.

7.86 seconds

d.

6.86 seconds

Discuss
Answer: (a).9.86 seconds
Q36.
A thermocouple junction in the form of 4 mm radius sphere is to be used to measure the temperature of a gas stream. The junction is initially at 35 degree Celsius and is placed in a gas stream which is at 300 degree Celsius. The thermocouple is removed from the hot gas stream after 10 seconds and kept in still air at 25 degree Celsius with convective coefficient 10 W/m² K. Find out the time constant of the thermocouple. Assume the thermos-physical properties as given below:

h = 37.5 W/m² K

p = 7500 kg/m³

c = 400 J/kg K

a.

6.67 seconds

b.

106.67 seconds

c.

206.67 seconds

d.

306.67 seconds

Discuss
Answer: (b).106.67 seconds
Q37.
What percentage of water an average human body can have?

a.

52%

b.

62%

c.

72%

d.

82%

Discuss
Answer: (c).72%
Q38.
According to lumped system analysis, solid possesses thermal conductivity that is

a.

Infinitely large

b.

Infinitely small

c.

Moderate

d.

50% small

Discuss
Answer: (a).Infinitely large
Q39.
The temperature and rate of heat conduction are undoubtedly dependent on

a.

Time coordinates

b.

Space coordinates

c.

Mass coordinates

d.

Both time and space coordinates

Discuss
Answer: (d).Both time and space coordinates
Q40.
Lumped parameter analysis for transient heat conduction is essentially valid for

a.

B I < 0.1

b.

1 < B I < 10

c.

0.1 < B I < 0.5

d.

It tends to infinity

Discuss
Answer: (a).B I < 0.1
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