( ) ... _______________________
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( ) .
- .
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- .
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.
, .
( ) - __________
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, (5.1)
Q - , , ;
l - , /(.);
- 䳺 , 0/;
F - , 2;
t - , .
. 5.1. :
- ; - ;
-
(5.2)
Q - , , ;
α - () (), /(2× );
t 1 - ,0;
t 2 - , 0;
F - , 2;
t - , .
3. .
Q = K×Dt×F×t, (5.3)
Q - , , ;
- , /(2×);
Dt - (t ) , (t ), Dt = t - t , 0;
F - , 2;
t - , 0.
ʳ , , , :
q =Q/F×t=K×Dt, (5.4)
q − , /2.
|
|
t, 0C t, 0C
. 5.2. : ; - :
Nu = (Gr * Pr) n (5.5)
Nu = 0,17 Re 0,33 Pr 0,43 Gr 0,1 (Pr / Pr ) 0,25 (5.6)
Nu = 0,021 Re 0,8 Pr 0,43(Pr p/ Pr )0,25 (5.7)
. 5.3. :
- ; - ; - : 1 - ; 2 -
:
Nu = C(Pr × G × ) 0,25, (5.8)
- ( 0,943, 0,728);
G - ;
- .
. 5.4. :
- ();
-
4. ,