Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 7th Sem New 2171911 Advance Heat Transfer Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VII (New) EXAMINATION ? WINTER 2019
Subject Code: 2171911 Date: 23/11/2019
Subject Name: Advance Heat Transfer
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) What are Heisler charts? How these charts are used to obtain temperature
distribution?
03
(b) Define Biot number and Fourier number? State their significances? 04
(c) Draw the boiling curve and identify the burnout point on the curve.
Explain how burnout is caused. Why is the burnout point avoided in the
design of boilers?
07
Q.2 (a) With suitable examples, explain in brief about periodic variation and non-
periodic variation transient heat transfer.
03
(b) Explain all the different mechanisms of heat transfer from the human
body (a) Through the skin, and (b) through the lungs.
04
(c) What is an irregular boundary? What is a practical way of handling
irregular boundary surfaces with the finite difference method?
07
OR
(c) What is lumped system analysis? Derive equation for lumped parameter
analysis.
07
Q.3 (a) Differentiate clearly between boiling and condensation. 03
(b) Define the following terms used in the finite difference formulation:
Node, Nodal Network, Volume Element, and Nodal Spacing.
04
(c) Explain radial fins of rectangular and parabolic profiles. 07
OR
Q.3 (a) Differentiate clearly between dropwise condensation and filmwise
condensation.
03
(b) Explain in brief about free convection and force convection with suitable
examples.
04
(c) Define fin efficiency and fin effectiveness. Why is the insulated-tip
solution important for the fin problems?
07
Q.4 (a) What do you mean by extended surfaces? Under what circumstances, one
should opt for extended surfaces?
03
(b) Write a short note on Emissivity and absorptivity of gases and gas
mixtures.
04
(c) 25mm thick steel plate (K= 48 W/mk) with uniform heat generation of
300*10
5
W/m
3
having surface temperatures of 453k and 393k
respectively. Determine :
a) The temperature distribution across the plate,
b) The position and value of maximum temperature,
c) The flow of heat from each surface of the plate.
07
OR
Q.4 (a) Explain the function of extended surfaces with classification. 03
(b) Define mean bulk temperature and mean film temperature with their
significances.
04
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VII (New) EXAMINATION ? WINTER 2019
Subject Code: 2171911 Date: 23/11/2019
Subject Name: Advance Heat Transfer
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) What are Heisler charts? How these charts are used to obtain temperature
distribution?
03
(b) Define Biot number and Fourier number? State their significances? 04
(c) Draw the boiling curve and identify the burnout point on the curve.
Explain how burnout is caused. Why is the burnout point avoided in the
design of boilers?
07
Q.2 (a) With suitable examples, explain in brief about periodic variation and non-
periodic variation transient heat transfer.
03
(b) Explain all the different mechanisms of heat transfer from the human
body (a) Through the skin, and (b) through the lungs.
04
(c) What is an irregular boundary? What is a practical way of handling
irregular boundary surfaces with the finite difference method?
07
OR
(c) What is lumped system analysis? Derive equation for lumped parameter
analysis.
07
Q.3 (a) Differentiate clearly between boiling and condensation. 03
(b) Define the following terms used in the finite difference formulation:
Node, Nodal Network, Volume Element, and Nodal Spacing.
04
(c) Explain radial fins of rectangular and parabolic profiles. 07
OR
Q.3 (a) Differentiate clearly between dropwise condensation and filmwise
condensation.
03
(b) Explain in brief about free convection and force convection with suitable
examples.
04
(c) Define fin efficiency and fin effectiveness. Why is the insulated-tip
solution important for the fin problems?
07
Q.4 (a) What do you mean by extended surfaces? Under what circumstances, one
should opt for extended surfaces?
03
(b) Write a short note on Emissivity and absorptivity of gases and gas
mixtures.
04
(c) 25mm thick steel plate (K= 48 W/mk) with uniform heat generation of
300*10
5
W/m
3
having surface temperatures of 453k and 393k
respectively. Determine :
a) The temperature distribution across the plate,
b) The position and value of maximum temperature,
c) The flow of heat from each surface of the plate.
07
OR
Q.4 (a) Explain the function of extended surfaces with classification. 03
(b) Define mean bulk temperature and mean film temperature with their
significances.
04
2
(c) An ordinary egg can be approximated as a 50mm diameter sphere with
approximately 75% water. The egg is initially at a uniform temperature
of 5?C and is dropped into boiling water at 95?C. Taking the convection
heat transfer coefficient to be h=1200W/m
2 0
C, determine how long it
will take for the center of the egg to reach 70?C. Take thermal
conductivity and diffusivity of eggs at the average temperature of 37.5?C;
k =0.627W/m
0
C , A1 = 1.9958, ? = 0.151?10
-6
m
2
/s and
?1= 3.0753.
07
Q.5 (a) What is Beer?s law? Why do surfaces absorb differently for solar or earth
bound radiation?
03
(b) What do you mean by ?heat generation?? With suitable examples,
explain in brief about ?uniform heat generation?.
04
(c) Explain effect of radiation on measurement of temperature by a bare
thermometer. A bare thermometer measuring the temperature of a gas
body reads 600K. The surrounding walls are at 500K. The thermometer
bulb is 3mm in diameter and is spherical, its surface emissivity being 0.7.
The convective heat transfer coefficient over the surface is 40W/m
2
K.
Determine the gas temperature and error involved.
07
OR
Q.5 (a) What is latent heat? How is the latent heat loss from the human body
affected by (a) skin wetness and (b) Relative humidity of the
environment?
03
(b) Derive Nusselt theory of laminar condensation on vertical plate. 04
(c) A thermocouple (?=0.6) is used to measure the temperature of flue gases
in a large duct. The temperature of the duct wall is 20
0
C and the
temperature measured by the thermocouple is 500
0
C. The convective
heat transfer coefficient is 200W/m
20
C. Determine the true gas
temperature and error involved.
A thin radiation shield (?=0.3) is enveloped to minimize the error.
Estimate the error for the above case.
07
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This post was last modified on 20 February 2020