Q7/ A 50-m-long section of a steam pipe whose outer diameter is 10 cm passes through an open space at 15°C. The average temperature of the outer surface of the pipe is measured to be 150°C. If the combined heat transfer coefficient on the outer surface of the pipe is 20 W/m2 °C, determine (a) the rate of heat loss from the steam pipe, (b) the annual cost of this energy lost if steam is generated in a natural gas furnace that has an efficiency of 75 percent and the price of natural gas is $0.52/therm (1 therm = 105,500 kJ), and (c) the thickness of fiberglass insulation (k = 0.035 W/m °C) needed in order to save 90 percent of the heat lost. Assume the pipe temperature to remain constant at 150°C . .

Q7/ A 50-m-long section of a steam pipe whose outer diameter is 10 cm passes through an open space at 15°C. The average temperature of the outer surface of the pipe is measured to be 150°C. If the combined heat transfer coefficient on the outer surface of the pipe is 20 W/m2 °C, determine (a) the rate of heat loss from the steam pipe, (b) the annual cost of this energy lost if steam is generated in a natural gas furnace that has an efficiency of 75 percent and the price of natural gas is $0.52/therm (1 therm = 105,500 kJ), and (c) the thickness of fiberglass insulation (k = 0.035 W/m °C) needed in order to save 90 percent of the heat lost. Assume the pipe temperature to remain constant at 150°C . .

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Question

Q7/ A 50-m-long section of a steam pipe whose outer diameter is 10 cm passes
through an open space at 15°C. The average temperature of the outer surface of the
pipe is measured to be 150°C. If the combined heat transfer coefficient on the outer
surface of the pipe is 20 W/m2 °C, determine (a) the rate of heat loss from the
steam pipe, (b) the annual cost of this energy lost if steam is generated in a natural
gas furnace that has an efficiency of 75 percent and the price of natural gas is
$0.52/therm (1 therm = 105,500 kJ), and (c) the thickness of fiberglass insulation
(k = 0.035 W/m °C) needed in order to save 90 percent of the heat lost. Assume
the pipe temperature to remain constant at 150°C

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