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| \( R_t \;=\; \dfrac{ ln \left( \dfrac{ r_2 }{ r_1 } \right) }{ 2 \cdot \pi \cdot k \cdot L } \) |
| Symbol |
English |
Metric |
| \( R_t \) = thermal resistance |
\(hr-F\;/\;Btu\) |
\(K\;/\;W\) |
| \( ln \) = natural logarithm |
\(dimensionless\) |
\(dimensionless\) |
| \( r_2\) = radius outside diameter (OD) |
\(in\) |
\(mm\) |
| \( r_1 \) = radius inside diameter (ID) |
\(in\) |
\(mm\) |
| \( \pi \) = Pi |
\(3.141 592 653 ...\) |
\(3.141 592 653 ...\) |
| \( k \) = thermal conductivity |
\(Btu-ft\;/\;hr-ft^2-F\) |
\(W\;/\;m-K\) |
| \( L \) = material length |
\(ft\) |
\(m\) |
