PRENOS TOPLOTE
PRENOS TOPLOTE
PRENOS TOPLOTE
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<strong>PRENOS</strong> <strong>TOPLOTE</strong> – NESTACIONARNI <strong>PRENOS</strong> <strong>TOPLOTE</strong><br />
TELO KONČNIH DIMENZIJ<br />
Θ =<br />
2 ⋅<br />
∑ ∞<br />
n=<br />
0<br />
( −1)<br />
1<br />
( n + )<br />
2<br />
n<br />
⋅ e<br />
⋅π<br />
−<br />
1<br />
( n+<br />
)<br />
2<br />
2<br />
2<br />
π Fo<br />
⋅ cos<br />
1<br />
( n + )<br />
2<br />
⋅π<br />
⋅ n<br />
Θ = ⋅e<br />
π<br />
⎛<br />
2<br />
⎞<br />
⎜<br />
π<br />
− ⎟<br />
⋅Fo<br />
4 ⎝ 4 ⎠<br />
⎛ π ⋅ x ⎞<br />
⋅cos⎜<br />
⎟<br />
⎝ 2⋅<br />
L ⎠<br />
Na površini (x = L) je tok iz okolice enak toku v telesu, zato lahko zapišemo<br />
h⋅<br />
Fo Fo<br />
8 ⎜ ⎛<br />
2<br />
2<br />
π<br />
⎟ ⎞<br />
⎞<br />
⎟<br />
⎜ ⎛ π<br />
− ⋅<br />
− ⋅<br />
4<br />
⎝ ⎠<br />
2<br />
1 0<br />
⋅e<br />
2<br />
⎜ 4 ⎟<br />
⎝ ⎠<br />
( T −T<br />
) ⋅ ⋅e<br />
= λ ⋅( T −T<br />
)<br />
1<br />
0<br />
π<br />
⋅<br />
L<br />
Sledi definicija Nusseltovega števila in trditev<br />
- toplotna prestopnost ni odvisna od časa<br />
Nu<br />
=<br />
h⋅<br />
L<br />
λ
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