blob: 5982e7d1a4e59d800194255beaddf17149493439 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
clc;
clear;
//Example 6.13
Cpf=4.18 //[kJ/kg.K]
dT1=18 //[K]
dT2=17 //[K]
dT3=34 //[K]
mf_dot=4 //[kg/s]
Ts=394 //[K]
bp=325 //Bp of water at 13.172 kPa [K]
dT=Ts-bp //[K]
lambda_s=2200 //[kJ/kg]
T1=Ts-dT1 //[K]
lambda1=2249 //[kJ/kg]
lambda_v1=lambda1 //[kJ/kg]
T2=T1-dT2 //[K]
lambda2=2293 //[kJ/kg]
lambda_v2=lambda2 //[kJ/kg]
T3=T2-dT3 //[K]
lambda3=2377 //[kJ/kg]
lambda_v3=lambda3 //[kJ/kg]
ic=0.1 //Initial conc of solids
fc=0.5 //Final conc of solids
m3dot_dash=(ic/fc)*mf_dot //[kg/s]
mv_dot=mf_dot-m3dot_dash //Total evaporation in [kg/s]
//Material balance over first effect
//mf_dot=mv1_dot_m1dot_dash
//Energy balance:
//ms_dot*lambda_s=mf_dot*(Cpf*(T1-Tf)+mv1_dot*lambda_v1)
//Material balance over second effect
//m1dot_dash=mv2_dot+m2dot_dash
//Enthalpy balance:
//mv1_dot*lambda_v1+m1dot_dash(cp*(T1-T2)=mv2_dot*lambda_v2)
//Material balance over third effect
//m2dot_dash=mv3_dot+m3dot+dash
//Enthalpy balance:
//mv2_lambda_v2+m2dot_dash*cp*(T2-T3)=mv3_dot*lambda_v3
294
mv2_dot=3.2795/3.079 //[kg/s]
mv1_dot=1.053*mv2_dot-0.1305 //[kg/s]
mv3_dot=1.026*mv2_dot+0.051 //[kg/s]
ms_dot=(mf_dot*Cpf*(T1-294)+mv1_dot*lambda_v1)/lambda_s //[kg/s]
eco=mv_dot/ms_dot //Steam economy
eco=round(eco)
printf("\nSteam economy is %d\n",eco);
U1=3.10 //[kW/sq m.K]
U2=2 //[kW/sq m.K]
U3=1.10 //[kW/sq m.K]
//First effect:
A1=ms_dot*lambda_s/(U1*dT1) //[sq m]
A2=mv1_dot*lambda_v1/(U2*dT2) //[sq m]
A3=mv2_dot*lambda_v2/(U3*dT3) //[sq m]
//Areas are calculated witha deviation of +-10%
printf("\nArea pf heat transfer in each effect is %f sq m\n",A3)
|
