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

A vertical steam pipe of diameter 8 cm and emissivity e=0.8 has it's surface at 95^{0}C. The surrounding air and the temperature of the room and things in it are at 27^{0}C.

What is the heat emission rate H from the pipe, for meter length, by radiation?

2. Relevant equations

Stefan's law: [itex]R=e\sigma T^4[/itex]

[tex]\sigma=5.672\times 10^{-8}\left[Watt/m^2\right][/tex]

[tex]1\left[Calorie\right]=4.186\left[Joule\right][/tex]

3. The attempt at a solution

[tex]R=0.8\cdot 5.672\times10^{-8}\left(373^4-300^4\right)=511\left[Watt/m^2\right][/tex]

[tex]H=511\cdot \pi \cdot 0.08\cdot 1=128\left[Watt/m\right][/tex]

[tex]128\left[Watt\right]\div 4.186=30.6\left[Calorie/Sec/m\right][/tex]

The answer, according to the book, is [itex]29\left[Calorie/Sec/m\right][/itex]

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# Homework Help: Energy emitted by radiation from a pipe

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