, ;
t- , º.
4.14:
4.15:
w,/
4.8
. 10 .
δ2 :
1/ = 1/α1 + 1/α2 + (δ1/λ1 + δ2/λ2 + δ3/λ3), (4.17)
δ1 , 10 [4]; δ3 , , 1 [3]; λ1 , 53,3 /(); λ2 , 0,076 /(); λ3 , 57,8 /(); , /(2); α1 , /(2); α2 , /(2).
= Q/(FΔtcp), (4.18)
Q , ; F , 3; Δtcp .
F = πDL, (4.19)
D , 2,9 .
Δtcp= ((t1 t0) (t2 t0))/ln((t1 t0)/ (t2 t0)),
Δtcp = ((200 25) (110 25))/ln((200 25)/ (110 25)) = 124,7 ˚,
F = 3,142,912=109,272 2,
(4.18)
= (790,8105/3600)/(109,272124,7)=1,67 /(2),
α1 = 1,25(α1´ + α1´´), (4.20)
α1´ = (Nuλ)/D, (4.21)
λ , 0,031 /().
Nu = 0,0324Re0.8, (4.22)
:
Re = 0,27832,80,9461/2,110-5=3,51104
Nu = 0,0324351000,8=140,21,
(4.21), :
α1´ = (140,210,031)/2,8=1,6 /(2),
α1´´= (Nuλ)/d, (4.23)
Nu = 0,47Gr0.25, (4.24)
Gr ,
Gr = (gd3ρ2Δt)/(μ2 (T0+ tcp)), (4.25)
Δt ( 20 ˚).
Gr = (9,812,80,9461220)/((0,02110-3) 2(273+155)) =20,4109,
Nu = 0,47(20,4109)0.25=177,62
α1´´= (177,620,031)/2,8=2,03 /(2),
α1 = 1,25(1,6+2,03) =4,54 /(2),
|
|
α2 = α2´ + α2´´, (4.26)
α2´ , /(2); α2´´ , /(2).
α2´ = 1,08(Δt´/D)0,25, (4.27)
Δt´ ( 20 ˚).
α2´´= ε´0[(T/100)4(Tcp/100)4]/(T Tcp), (4.28)
ε´ , , 0,95; 0 , 5,7 /(24); T , ˚; Tcp , ˚.
T= 298 , T= 318 ;
α2´ = 1,08(20/2,9)0,25=1,76 /(2),
α2´´= 0,955,7[(318/100)4(298/100)4]/(318298) = 6,34/(2),
α2 =1,76+6,34 =8,1 /(2),
, :
1/1,67 = ¼,54+ 1/8,1 + (10/53,3 + δ2/0,076 + 1/57,8)
δ2=0,019 .
δ2 = 0,019 :
D = d + 2 δ2, (4.29)
D =2,8 + 20,019 =2,838 .
4.9
:
Δ = Δ + Δ, (4.47)
Δ , ; Δ , ; Δ , .
Δ :
Δ= ρ(1ε)gH, (4.48)
Δ= 1785(10,38)9,810,16 =1737,2 ,
:
Δmin= ΔKw2(εε0)/[(Kw21)(1ε0)], (4.49)
ε0 0,3. , :
Δmin=1737,22,52(0,380,3)/[(2,521)(10,3)] =336,8 .
Δ = ξ ρ(w/Fc)2/2. (4.50)
ξ = 0,75.
Δ = 0,750,966(0,26 /0,03)2/2 =27,21 .
Δ=27,21 Δmin.
Δ = 1737,2 .