Subject Code: 2153613
GUJARAT TECHNOLOGICAL UNIVERSITY
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BE - SEMESTER- V (New) EXAMINATION - WINTER 2019
Subject Name: Basics of Heat Transfer
Time: 10:30 AM TO 01:00 PM
Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
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Q.1
(a) Explain Fourier’s law of heat transfer. (MARKS 03)
(b) Explain convection heat transfer with suitable example. (MARKS 04)
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(c) Derive the general heat conduction equation in Cartesian co-coordinates. (MARKS 07)
Q.2
(a) Derive an expression for steady state heat conduction through composite wall. (MARKS 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? (MARKS 04)
(c) Explain various types of extended surfaces. Derive the expression for heat transfer through the rectangular fin. (MARKS 07)
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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. (MARKS 07)
Q.3
(a) The heat flux through a wood slab 50 mm thick, whose inner and outer surface temperatures are 40 and 20°C, respectively, has been determined to be 40 W/m². What is the thermal conductivity of the wood? (MARKS 03)
(b) Explain laws of radiation heat transfer in detail (any two). (MARKS 04)
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(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° C and the temperature of the outside of the insulation 60° C. Also find the interface temperature of layers. (MARKS 07)
OR
Q.3
(a) The convection heat transfer coefficient between a surface at 40°C and ambient air at 20°C is 20 W/m²K. Calculate the heat flux leaving the surface by convection. (MARKS 03)
(b) Explain Reynolds number, Nusselt Number in detail. (MARKS 04)
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(c) Elaborate the different feeding method for multi effect evaporator with neat sketch. (MARKS 07)
Q.4
(a) Elaborate plate type heat exchanger. (MARKS 03)
(b) Derive the expression for L.M.T.D. in counter current heat exchanger. (MARKS 04)
(c) Derive the expression for Prandtl analogy (MARKS 07)
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Q.4
(a) Explain boiling point elevation. (MARKS 03)
(b) Explain the shell and tube heat exchanger. (MARKS 04)
(c) Explain the construction and working of calendria type evaporators with neat sketch. (MARKS 07)
Q.5
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(a) What is condensation? List the factors on which condensation is depend. (MARKS 03)
(b) What is economy of evaporator? Explain any one method used to increase the economy of evaporator. (MARKS 04)
(c) Elaborate with neat sketch, falling film evaporator. (MARKS 07)
OR
Q.5
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(a) Explain film wise and drop wise condensation. (MARKS 03)
(b) Define following terms (MARKS 04)
- Effectiveness
- Absorptivity
- Reflectivity
- Transmissibility
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(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? (MARKS 07)
Date: 04/12/2019
Total Marks: 70
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This download link is referred from the post: GTU BE/B.Tech 2019 Winter Question Papers || Gujarat Technological University
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