Evaporadores Multiples

◦

◦

Q  = w  =  w ∗ Cp ∗ (T ) T ) t1  = 100

◦

t2  = 200

◦

tm  = tm ◦

tm t1  + t2  100 + 200 = = 150 F  2 2 ◦

Q = 75, 000 ∗ 0.63 ∗ (200 − 100) = 4, 725, 000Btu/h

Q = λ ∗ w λ

◦

w =

2

∗

Q 4, 725, 000 lb = = 4, 997.3559 λ 945.5 h

hio  = 1500Btu/h ∗ f t2 ∗

◦

DI  ∗ C  B as  = 144 ∗ P T  

P T 

as  =

17.25 ∗ (15/16 − 3/4) ∗ 7 = 1.667x10 144 ∗ 15/16

1

−

Gs  =

Gs  =

75, 000 1.667x10

1

−

ft

w as

= 4.472x105

Gs

lb ft ∗ h

µ Res  =

De ∗ Gs µ

◦

F 

De =

De =

4 ∗ Arealibre 4 ∗ 1/2P T x0.86P T  − 1/2πdo2 /4 = Primetrohumedo 1/2π ∗ do

(4 ∗ 1/2 ∗ (15/16)/12) ∗ (0.86 ∗ (15/16)/12) − (1/2 ∗ π ∗ ((3/4)/12)2 /4 = 4.44X 10 1/2 ∗ π ∗ (3/4)/12

2

−

ft

µ tm

µ  = 5.3Cp = 12.83lb/ft ∗ h Res

4.44x10 2 ∗ 447200 = 1547.6 12.83 L 1.3333 = = 30.02 De 4.44x10 2 −

Res  =

−

K  = 0.153

1/3

∗

 jH  =

k

0.14

−

 hD  Cp µ   µ  K 

µw

0.14

−

φ =

µ µw

ho K  = jH  φs De

1/3

 Cp µ  ∗

k

2

ho = 6.4 φs



0.153 4.44x10

1/3

2

−

 (0.63)(12.83)  0.153

φs

µw

tw  =  t c  + T c

= 82.7524

hio (T c − tc ) hio + ho

Btu/h ∗ f t2 ∗

tc ◦

BT U  h ∗ f t2 ∗ F 

)(

◦

BT U  h ∗ ft ∗ F 

tw  = 150 + tw 2µw  = 2(0.19cp)(2.42) = 0.9196

  1500 (250 − 150) = 244.7716 F  1500 + 82.7524 µw ◦

µw

φs 0.14

0.14

−

φs  =

µ µw

=

 12.83 

= 1.4463

0.9196

φ ho =

ho Btu φs  = (1.4463)(82.7524) = 119.6848 φs h ∗ f t2 ∗

◦

F  U c

hio ∗ ho hio + ho   1500 ∗ 119.6848 BT U  U c  =  = 110.8408 1500 + 119.6848 h ∗ f t2 U c  =

∗ F 

U d U d  =

Q At

t t = F T xMLDT 

MLDT  =

(T 1 − t2 ) − (T 2 − t1 )  (250 − 200) − (250 − 100) = = 91.0239 (T 1 − t2 ) (250 − 200) ln ln (T 2 − t1 ) (250 − 100)

F T 

R =

T 1 − T 2 250 − 250 = =0 t2 − t1 200 − 100

F T 

S  =

t2 − t1 200 − 100 = = 0.6667 T 1 − t1 250 − 100 t

Btu/h

U d  =

Q   4725000 Btu = = 73.79 At (703.5392)(91.0239) h ∗ ft2 ∗ Rd

Rd  =

110.8408 − 73.79 = 4.53x10 110.8408 ∗ 73.79

f t2 ∗ F  BT U 

3h∗

−

◦

F 

at in2

at

at  =

 No.detubos ∗ Areadeflujo/tubo 244 ∗ 0.268 = = 0.2084f t2 144 ∗ No.dePasos 144 ∗ 2

Gt  =

4, 997.3559 w lb = = 26, 263.4093 2 at 0.2048 ft ∗ h

T a  = 250F  lb ft ∗ h

µvap

µvap = 0.0130cp

 lb  2.42  lb ft h     = 0.0130cp  = 0.03146  1cp ft h ∗

∗

Ret  =

  1f t  DI  = 0.0584in = 0.0487f t 12in   lb (0.0487f t) ∗ 26, 263.4093

Ret  =

0.03146

lb ft ∗ h

f t2 ∗ h

DI  ∗ Gt µ

= 47722.9749 A  = a L ∗ N t 

a = 

N t A =

f t2 0.1963  lin (16 0 f t) (224) = 703.5392ft2 ft



υ = 20





f t2 lb

1/2 = 0.00080 62.5 Ret f  = 0.00018f t2 s =

t  =

1 2

∗

f  ∗ G2t ∗ L ∗ n 5.2x1010 ∗ Ds ∗ φt



1 ∆P t  = 2

∗

0.00018 ∗ 308602 ∗ 16 ∗ 2 lb = 1.3486 5.2x1010 ∗ 0.0487 ∗ ∗0.00080 in2



De =



De =

4(readeflujo) (P rimetrohmedofriccional)

4(1/2 ∗ P T (0.86P T  − (1/2 ∗ π ∗ do2 )/4)) 1/2 ∗ π ∗ do + 1/2 ∗ π ∗ di

P T 



4(1/2 ∗ (

De =

15/16  15/16 − (1/2 ∗ π ∗ (3/4)2 )/4)) )(0.86 ∗ 12 12 = 44.5525f t  3/4 17(1/4) 1/2 ∗ π ∗ + 1/2 ∗ π 12 12 2 /in2 .

P s  =

P s  =

f  ∗ Gs 2 L ∗ n 5.22x101 0(De )(s)(φs ) 

0.003 ∗ (447, 200)2 ∗ 16 ∗ 2 = 5.488x10 5.22x101 0(44.5525)( 1.04)(1.4463)

3

−

lb in2

◦

U 1 =

U 2 =

U 3 =

W/m2 K