Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 5th Sem New 2153613 Basics Of Heat Transfer Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? V (New) EXAMINATION ? WINTER 2019
Subject Code: 2153613 Date: 04/12/2019
Subject Name: Basics of Heat Transfer
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instruction0073:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Explain Fourier?s law of heat transfer. 03
(b) Explain convection heat transfer with suitable example. 04
(c) Derive the general heat conduction equation in Cartesian co-coordinates.
07
Q.2 (a) Derive an expression for steady state heat conduction through composite
wall.
03
(b) The wall of an industrial furnace is constructed from 0.2 m thick fireclay
brick having a thermal conductivity of 2.0 W/mK. Measurements made
during steady state operation reveal temperatures of 1500 and 1250 K at
the inner and outer surfaces, respectively. What is the rate of heat loss
through a wall which is 0.5 m by 4 m on a side?
04
(c) Explain various types of extended surfaces. Derive the expression for heat
transfer through the rectangular fin.
07
OR
(c) What do you mean by critical radius of insulation? Explain the significance
of critical radius, Derive expression of critical radius for Spherical shape.
07
Q.3 (a) The heat flux through a wood slab 50 mm thick, whose inner and outer
surface temperaturesare 40 and 20?C, respectively, has been determined to
be 40 W/m
2
. What is the thermalconductivity of the wood?
03
(b) Explain laws of radiation heat transfer in detail (any two). 04
(c) Calculate the rate of heat loss through the vertical walls of a boiler furnace
of size 4 m by 3 m by 3 m high. The walls are constructed from an inner
fire brick wall 25 cm thick of thermal conductivity 0.4 W/mK, a layer of
ceramic blanket insulation of thermal conductivity 0.2 W/mK and 8 cm
thick, and a steel protective layer of thermal conductivity 55 W/mK and 2
mm thick. The inside temperature of the fire brick layer was measured at
600
0
C and the temperature of the outside of the insulation 60
0
C. Also find
the interface temperature of layers.
07
OR
Q.3 (a) The convection heat transfer coefficient between a surface at 40?C and
ambient air at 20?C is20 W/m
2
K. Calculate the heat flux leaving the
surface by convection.
03
(b) Explain Reynolds number, Nusselt Number in detail. 04
(c) Elaborate the different feeding method for multi effect evaporator with
neat sketch.
07
Q.4 (a) Elaborate plate type heat exchanger. 03
(b) Derive the expression for L.M.T.D. in counter current heat exchanger. 04
(c) Derive the expression for Prandtl analogy 07
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? V (New) EXAMINATION ? WINTER 2019
Subject Code: 2153613 Date: 04/12/2019
Subject Name: Basics of Heat Transfer
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instruction0073:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Explain Fourier?s law of heat transfer. 03
(b) Explain convection heat transfer with suitable example. 04
(c) Derive the general heat conduction equation in Cartesian co-coordinates.
07
Q.2 (a) Derive an expression for steady state heat conduction through composite
wall.
03
(b) The wall of an industrial furnace is constructed from 0.2 m thick fireclay
brick having a thermal conductivity of 2.0 W/mK. Measurements made
during steady state operation reveal temperatures of 1500 and 1250 K at
the inner and outer surfaces, respectively. What is the rate of heat loss
through a wall which is 0.5 m by 4 m on a side?
04
(c) Explain various types of extended surfaces. Derive the expression for heat
transfer through the rectangular fin.
07
OR
(c) What do you mean by critical radius of insulation? Explain the significance
of critical radius, Derive expression of critical radius for Spherical shape.
07
Q.3 (a) The heat flux through a wood slab 50 mm thick, whose inner and outer
surface temperaturesare 40 and 20?C, respectively, has been determined to
be 40 W/m
2
. What is the thermalconductivity of the wood?
03
(b) Explain laws of radiation heat transfer in detail (any two). 04
(c) Calculate the rate of heat loss through the vertical walls of a boiler furnace
of size 4 m by 3 m by 3 m high. The walls are constructed from an inner
fire brick wall 25 cm thick of thermal conductivity 0.4 W/mK, a layer of
ceramic blanket insulation of thermal conductivity 0.2 W/mK and 8 cm
thick, and a steel protective layer of thermal conductivity 55 W/mK and 2
mm thick. The inside temperature of the fire brick layer was measured at
600
0
C and the temperature of the outside of the insulation 60
0
C. Also find
the interface temperature of layers.
07
OR
Q.3 (a) The convection heat transfer coefficient between a surface at 40?C and
ambient air at 20?C is20 W/m
2
K. Calculate the heat flux leaving the
surface by convection.
03
(b) Explain Reynolds number, Nusselt Number in detail. 04
(c) Elaborate the different feeding method for multi effect evaporator with
neat sketch.
07
Q.4 (a) Elaborate plate type heat exchanger. 03
(b) Derive the expression for L.M.T.D. in counter current heat exchanger. 04
(c) Derive the expression for Prandtl analogy 07
2
OR
Q.4 (a) Explain boiling point elevation. 03
(b) Explain the shell and tube heat exchanger. 04
(c) Explain the construction and working of calendria type evaporators with
neat sketch.
07
Q.5 (a) What is condensation? List the factors on which condensation is depend. 03
(b) What is economy of evaporator? Explain any one method used to increase
the economy of evaporator.
04
(c) Elaborate with neat sketch, falling film evaporator. 07
OR
Q.5 (a) Explain film wise and drop wise condensation. 03
(b) Define following terms
1. Effectiveness 2. Absorptivity
3. Reflectivity 4. Transmissibility
04
(c) A hot fluid enters a concentric pipe apparatus at a temperature of 148 ?C
and is to cooled to 93 ?C by a cold fluid entering at 37 ?C and heated to 65
?C. Shall they be directed in parallel flow or counter flow?
07
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This post was last modified on 20 February 2020