ASSIGNMENT ONE
QUESTION ONE
a) A 250mm steam main, 225metres long is covered with 50mm of high temperature
insulation (k = 0.095W/m K) and 40 mm of low temperature insulation (k = 0.065W/m K).
The inner and outer surface temperatures as measured are 400°C and 50°C respectively.
Calculate :
(i)
The total heat loss per hour.
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(ii)
The total heat loss per m2 of outer surface.
[5]
(iii)
The heat loss per m2 of pipe surface.
[4]
(iv)
The temperature between the two layers of insulation.
[4]
Neglect heat conduction through pipe material
b) A steam pipe of 160 mm inside diameter and 170 mm outside diameter (k = 58 W/m K) is
covered with first layer of insulating material of 30 mm thickness (k = 0.17 W/m K) and
second layer of insulating material of 50 mm thickness (k = 0.093 W/m K). The temperature
of steam passing through the pipe is 300°C and ambient air temperature surrounding the
pipe is 30°C. Taking inner and outer heat transfer co-efficients 30 and 5.8 W/m2 K
respectively, find the heat lost per metre length of pipe.
[7]