(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A vertical steam pipe of outside diameter 7.5 cm and height 4 m has its outer surface at the constant temperature of 95^{0}C. The surrounding air is at atmospheric pressure and at 20^{0}C.

How much heat is delivered to the air by natural convection in 1 hr?

2. Relevant equations

[tex]\mbox{The heat convection current H: }H=hA\,\Delta t[/tex]

[tex]\mbox{Coefficient of naural convection in air at atmospheric pressure for a vertical pipe (diameter D): }h=1.00\times10^{-4\left(\frac{\Delta t}{D}\right)^{1/4}}[/tex]

3. The attempt at a solution

[tex]h=1.00\times10^{-4\left(\frac{75}{7.5}\right)^{1/4}=0.00018[/tex]

[tex]H=0.00018\cdot\frac{\pi\cdot 7.5^2}{4}400\cdot 75=235.7\left[Cal/Sec\right]=848,469\left[Cal/hr\right][/tex]

The answer, according to the book, should be 454,000.

If this isn't the place for this subject, please guide me to another sight that deals with those kind of problems.

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# Homework Help: Heat transmitted in convection from a pipe

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