Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 6th Sem Old 160202 Automobile Heat Transfer Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VI (OLD) EXAMINATION ? WINTER 2018
Subject Code:160202 Date: 15/12/2018
Subject Name: Automobile Heat Transfer
Time: 02:30 PM TO 05:00 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) Write down general heat conduction equation for Cartesian co-ordinate and
derive equation for heat transfer through a plane wall.
07
(b) What is convection? Explain types of convection and explain newton?s law of
cooling.
07
Q.2 (a) ?It is true that insulation is provided to reduce heat transfer rate but due to
insulation heat transfer rate is not reduced always? Justify the statement
analytically.
07
(b) Explain hydrodynamic (velocity) boundary layer. 07
OR
(b) A wall of a furnace is made up of inside layer of silica brick 120 mm thick
covered with a layer of magnesite brick 240 mm thick. The temperature at the
inside surface of silica brick wall and outside surface of magnesite brick wall are
725
o
C and 110
o
C respectively. The contact thermal resistance between the two
walls at the interface is 0.0035
o
C/W per unit wall area. If thermal conductivities
of silica and magnesite bricks are 1.7 W/mK and 5.8 W/mK,
Calculate
1. Rate of heat loss unit area of wall
2. Temperature drop at the interface.
07
Q.3 (a) Derive an expression for heat flow through ?Rectangular Fin?. 07
(b) The resistance R experienced by a partially submerged body depends upon the
velocity V, length of the body L, viscosity of fluid ?, density of fluid ? and
gravitational acceleration g. Obtain a dimensionless expression for R using
Buckingham ? method.
07
OR
Q.3 (a) Write a short notes on the following: (A) Total emissive power, (B) Irradiation,
(C) Radiosity, (D) Gray Body.
07
(b) Assuming the sun to be a black body having a surface temperature of 5800 K,
calculate (a) total emissive power, (b) the wavelength at which the maximum
spectral intensity occurs, (c) the maximum value of Eb? (d) the total amount of
radiant energy emitted by the sun per unit time if its diameter can be assumed to
be 1.391?10
9
m.
07
Q.4 (a) Derive an expression for LMTD in case of counter flow heat exchanger. 07
(b) An oil of 0.27 kg/sec (Cp= 2.09 kJ/kg K) has to be cool from 80
o
C to 40
o
C using
coolant flow of 0.27 kg/sec (Cp= 4.18 kJ/kg K) at 30
o
C. Give your choice for
selection of heat exchanger with reason. Calculate the area of heat exchanger.
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VI (OLD) EXAMINATION ? WINTER 2018
Subject Code:160202 Date: 15/12/2018
Subject Name: Automobile Heat Transfer
Time: 02:30 PM TO 05:00 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) Write down general heat conduction equation for Cartesian co-ordinate and
derive equation for heat transfer through a plane wall.
07
(b) What is convection? Explain types of convection and explain newton?s law of
cooling.
07
Q.2 (a) ?It is true that insulation is provided to reduce heat transfer rate but due to
insulation heat transfer rate is not reduced always? Justify the statement
analytically.
07
(b) Explain hydrodynamic (velocity) boundary layer. 07
OR
(b) A wall of a furnace is made up of inside layer of silica brick 120 mm thick
covered with a layer of magnesite brick 240 mm thick. The temperature at the
inside surface of silica brick wall and outside surface of magnesite brick wall are
725
o
C and 110
o
C respectively. The contact thermal resistance between the two
walls at the interface is 0.0035
o
C/W per unit wall area. If thermal conductivities
of silica and magnesite bricks are 1.7 W/mK and 5.8 W/mK,
Calculate
1. Rate of heat loss unit area of wall
2. Temperature drop at the interface.
07
Q.3 (a) Derive an expression for heat flow through ?Rectangular Fin?. 07
(b) The resistance R experienced by a partially submerged body depends upon the
velocity V, length of the body L, viscosity of fluid ?, density of fluid ? and
gravitational acceleration g. Obtain a dimensionless expression for R using
Buckingham ? method.
07
OR
Q.3 (a) Write a short notes on the following: (A) Total emissive power, (B) Irradiation,
(C) Radiosity, (D) Gray Body.
07
(b) Assuming the sun to be a black body having a surface temperature of 5800 K,
calculate (a) total emissive power, (b) the wavelength at which the maximum
spectral intensity occurs, (c) the maximum value of Eb? (d) the total amount of
radiant energy emitted by the sun per unit time if its diameter can be assumed to
be 1.391?10
9
m.
07
Q.4 (a) Derive an expression for LMTD in case of counter flow heat exchanger. 07
(b) An oil of 0.27 kg/sec (Cp= 2.09 kJ/kg K) has to be cool from 80
o
C to 40
o
C using
coolant flow of 0.27 kg/sec (Cp= 4.18 kJ/kg K) at 30
o
C. Give your choice for
selection of heat exchanger with reason. Calculate the area of heat exchanger.
07
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2
OR
Q.4 (a) Derive formula for effectiveness of parallel flow heat exchanger. 07
(b) What do you mean by fouling? State the causes of fouling. 07
Q.5 (a) What is the function of radiator in an automobile? Explain with a neat sketch
construction and working of a radiator.
07
(b) What is boiling? Explain boiling regimes. 07
OR
Q.5 (a) What are the functions of cap which is used on a radiator? Explain construction
and working of a radiator cap.
07
(b) What is condensation? Explain film wise condensation and drop wise
condensation.
07
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This post was last modified on 20 February 2020