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Reg No.: Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
Fourth semester B.Tech examinations (S), September 2020

Course Code: CH202
Course Name: PROCESS HEAT TRANSFER (CH)
Max. Marks: 100 Duration: 3 Hours
PARTA
Answer any two questions. Each question carries 15 marks.

1 a) Derive the expression for temperature distribution in a hollow cylinder without 9
internal energy generation. Also obtain the expression for heat flux. State your
assumptions properly.

b) Explain the significance of Biot and Fourier Numbers. 6

2 a) Analuminium sphere of weight 2.5 kg is initially kept at a temperature of 350 °C. It 9
is suddenly immersed into a fluid kept at 20 ° C. The convective heat transfer
coefficient is 58 W/m°K. Estimate the time required to 0001 the sphere to 100 °C
using lumped capacity analysis method. Given density of aluminium = 2700 kg/m? $
specific heat = 900 J/kgK, thermal conductivity = 205 W/mK.

b) Describe different types of boundary conditions applied to heat conduction 6
problems.

3 a) What is meant by thermal resistance? Explain the electrical analogy for solving 5
heat transfer problems.

b) Derive the expression for critical thickness of insulation for a cylindrical system. 8
Explain optimum thickness of insulation.
€) State Fourier’s law of heat conduction 2
PART ‏تا‎
‎Answer any two questions. Each question carries 15 marks

4 a) Develop the expression for Reynold’s analogy between momentum and heat 15
transfer. State the expression for Colburn analogy.

5 a) Describe the basic construction of a shell and tube heat exchanger with a neat 15
diagram.

6 a) Air at a temperature of 300 °C flows with a velocity of 10 m/s over a flat plate of 7
length 0.5 m. Compute the cooling rate per unit width of the plate needed to

maintain it at a surface temperature of 27 °C. (Given properties of air at 437 K are

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