Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 5th Sem New 2151909 Heat Transfer Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (NEW) EXAMINATION ? WINTER 2018
Subject Code:2151909 Date:27/11/2018
Subject Name: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.
4. Use of air table, steam table, heat exchanger chart is permitted.
MARKS
Q.1 (a) What is insulation? State its six applications in engineering
field.
03
(b) It is observed that the intensity of the radiation emitted by the sun
is maximum at a wavelength of 0.5 ?. Assuming the sun to be
black body. Calculate its surface temperature and emissive
power.
04
(c) Saturated steam at 120 ?C is condensing on the outer tube surface
of a single pass heat exchanger. The overall heat transfer
coefficient is 1800 W/m
2
K. Determines the surface area of a heat
exchanger capable of heating 1000 kg/h of water from 20 ?C to
90 ?C. Also calculate the rate of condensation of steam. Assume
latent heat of steam is 2200 KJ/Kg.
07
Q.2 (a) What is dimensional analysis? Explain dimensional
homogeneity.
03
(b) A copper pipe (temperature 55 ?C) is kept in atmosphere
(temperature 35 ?C). The length and diameter of pipe is 1m and
50 mm respectively. The air velocity is 3 m/s. use the co-relation
Nu= 0.0239 (Re)
0.805
. Calculate heat loss from the pipe.
04
(c) Derive the two dimensional energy equation for thermal
boundary layer over a flate plate.
07
OR
(c) By dimensional analysis, show that for force convection Nusselt
Number is a function of Reynold Number and Prandtl Number.
07
Q.3 (a) Explain film wise condensation. 03
(b) Emissivity of two large parallel plates maintained at 800 ?C and
300 ?C are 0.3 and 0.5 respectively. Find the net radiant heat
exchange per square meter for these plates.
04
(c) Derive equation of net heat transfer by radiation between two
infinite parallel plates.
07
OR
Q.3 (a) Define shape factor. What is shape factor with respect to itself if
the surface is concave, convex or flat?
03
(b) Differentiate between 1. Subcooled and saturated boiling 2.
Nucleate and film boiling
04
(c) State and prove Kirchof?s law of radiation. Derive Wein?s
displacement law.
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (NEW) EXAMINATION ? WINTER 2018
Subject Code:2151909 Date:27/11/2018
Subject Name: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.
4. Use of air table, steam table, heat exchanger chart is permitted.
MARKS
Q.1 (a) What is insulation? State its six applications in engineering
field.
03
(b) It is observed that the intensity of the radiation emitted by the sun
is maximum at a wavelength of 0.5 ?. Assuming the sun to be
black body. Calculate its surface temperature and emissive
power.
04
(c) Saturated steam at 120 ?C is condensing on the outer tube surface
of a single pass heat exchanger. The overall heat transfer
coefficient is 1800 W/m
2
K. Determines the surface area of a heat
exchanger capable of heating 1000 kg/h of water from 20 ?C to
90 ?C. Also calculate the rate of condensation of steam. Assume
latent heat of steam is 2200 KJ/Kg.
07
Q.2 (a) What is dimensional analysis? Explain dimensional
homogeneity.
03
(b) A copper pipe (temperature 55 ?C) is kept in atmosphere
(temperature 35 ?C). The length and diameter of pipe is 1m and
50 mm respectively. The air velocity is 3 m/s. use the co-relation
Nu= 0.0239 (Re)
0.805
. Calculate heat loss from the pipe.
04
(c) Derive the two dimensional energy equation for thermal
boundary layer over a flate plate.
07
OR
(c) By dimensional analysis, show that for force convection Nusselt
Number is a function of Reynold Number and Prandtl Number.
07
Q.3 (a) Explain film wise condensation. 03
(b) Emissivity of two large parallel plates maintained at 800 ?C and
300 ?C are 0.3 and 0.5 respectively. Find the net radiant heat
exchange per square meter for these plates.
04
(c) Derive equation of net heat transfer by radiation between two
infinite parallel plates.
07
OR
Q.3 (a) Define shape factor. What is shape factor with respect to itself if
the surface is concave, convex or flat?
03
(b) Differentiate between 1. Subcooled and saturated boiling 2.
Nucleate and film boiling
04
(c) State and prove Kirchof?s law of radiation. Derive Wein?s
displacement law.
07
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2
Q.4 (a) What is difference between heat transfer and thermodynamics? 03
(b) What is fouling? State the causes of fouling.
State the limitations of LMTD method. What is heat pipe?
04
(c) Derive equation of LMTD for counter flow heat exchanger. 07
OR
Q.4 (a) Which are the basic laws governing the heat transfer. State any
one.
03
(b) What is compact, multipass and regenerator type heat
exchanger? State six application of heat exchanger in the field of
engineering.
04
(c) Derive equation of effectiveness for parallel flow heat
exchanger.
07
Q.5 (a) What is Fourier?s law of heat conduction? State its assumptions. 03
(b) A steel pipe (k= 35 W/m K) with inner diameter 50 mm and outer
diameter 60 mm is insulated using insulation material having
(K=0.055 W/m.K). The temperature interface between pipe and
insulation is 573 K, while the temperature on outside of insulation
must not exceed 343 K, with permissible heat loss of 700 W/m.
calculate (1) the minimum thickness of insulation and (2) the
temperature of inside surface of pipe.
04
(c) Derive expression for temperature distribution and heat
dissipation in a straight infinitely long fin of rectangular profile.
07
OR
Q.5 (a) Define fin efficiency. Explain the situation, when addition of fin
to a surface is not useful.
03
(b) A steel rod (K= 54 W/ m? K) with a cross section of an equilateral
triangle (each side 5 mm) is 80 mm long. It is attached to a furnace
wall which is maintained at a temperature of 400 ?C. The
surrounding is at 50 ?C and surface conductance is 90 W/m
2
K.
Calculate the heat dissipated by the rod. Assume tip of the rod is
insulated.
04
(c) Derive expression for temperature distribution, under one
dimensional steady state heat conduction for the hollow cylinder.
07
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This post was last modified on 20 February 2020