Heat Transfer-1 (color)
Heat Transfer-1 (color)
Heat Transfer-1 (color)
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Example Calculation #1<br />
• Steam is transported through a 11/2 “ mild steel pipe. The inside<br />
and outside pipe wall temperatures are 205°F and 195°F,<br />
respectively. OD = 1.9” ; ID = 1.5”; k = 24.8 Btu.hr -1 .ft -1 .°F -1<br />
– 1) Find the heat loss for 10 feet of pipe<br />
– 2) FInd the heat flux based upon inside and outside surface<br />
areas.<br />
• <strong>Heat</strong> is transferred radially. The applicable scalar form of the<br />
Fourier rate equation is:<br />
qr = −kA<br />
For the steady state case, qr is constant<br />
dT ⎫<br />
dr ⎬<br />
A = 2 rL<br />
⎪<br />
⇒ qr = −k( 2 rL)<br />
⎪ ⎭<br />
dT<br />
dr<br />
rodr<br />
To<br />
qr ∫ = −2 kL ∫ dT ⇒ qr ln<br />
r<br />
ro ⎛ ⎞<br />
⎜ ⎟ = −2 kL( To − Ti )<br />
⎝ ⎠<br />
r i<br />
T i<br />
r i
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