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F1003 Pages: 2

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
SIXTH SEMESTER B.TECH DEGREE EXAMINATION(R&S), MAY 2019

Course Code: ME302
Course Name: Heat and Mass Transfer

PARTA
Answer any three full questions, each carries 10 marks.

What are the mechanisms of heat transfer? How are they distinguished from each
other?
A hollow sphere (k = 65 W/mK) of 120 mm inner diameter and 350 mm outer

diameter is covered 10 mm layer of insulation (k =10 W/mK). The inside and
outside temperatures are 5000 and 50°C respectively. Calculate the rate of heat
flow through this sphere.
Derive the general heat conduction equation in Cartesian coordinates
Explain velocity boundary layer and thermal boundary layer with neat sketches.
Discuss the significance Nusselt number and Prandtl number in convection
Air at 20°C at atmospheric pressure flows over a flat plate at a velocity of 3 m/s.
If the plate is 1 m wide and at 80°C, calculate the following at x = 300 mm.
i. Hydrodynamic boundary layer thickness

ii. Thermal boundary layer thickness

iii. Local friction coefficient

iv. Average heat transfer coefficient

v. Heat transfer rate

PART ‏تا‎
‎Answer any three full questions, each carries 10 marks.

An aluminium alloy fin (k = 200 W/mK) of 1 m width, 3.5 mm thick, and 2.5 cm
long protrudes from a wall. The base is at 420°C, the ambient air temperature is
30°C and the heat transfer coefficient is 11 W/m*.K. Find the rate of heat loss
and fin efficiency, if the fin tip is insulated.
Derive equations of temperature distribution and heat dissipation for an infinitely
long fin
Derive an expression for Log Mean Temperature Difference in the case of a
counter flow heat exchanger.

In a double pipe heat exchanger hot water flows at a rate of 14 kg/s and gets

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Duration: 3 Hours

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