blob: 7b641863c83c76f740df8c5bae79d6ac869143ec (
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
|
clear;
clc;
printf("\t Example 2.12\n");
// ammonia diffusing through inert air and air is non-diffusing
ya1=0.1;
ya2=0;
T=(293); //temperature in kelvin
pt=1*1.013*10^5; //total pressure in pascal
z=0.2*10^-2; //gas film thickness in m
Dab=.185*10^-4; //diffusion coefficient in m^2/s
R=8314; //universal gas constant
//part (i)when air is assumed to be stagnant and non-diffusing
Na=Dab*pt*log((1-ya2)/(1-ya1))/(z*R*T); //diffusion flux in kmol/m^2*s
mw=17; //molecular weight of ammonia
massflux=Na*mw; //mass flux of given NH3
printf("\n diffusion flux when total presssure is 1atm and air is non-diffusing :%f *10^-4 kg/m^2*s ",massflux/10^-4);
//part (ii) when pressure is increased to 10atm
//Dab_1/Dab_2=pt_2/pt_1
pt_2=10; //final pressure in atm
pt_1=1; //initially pressure was 1atm
Dab_1=.185; //initially diffusion coefficient was.185
Dab_2=Dab_1*pt_1/pt_2; //for gases Dab is proportional to 1/pt
Dab=Dab_2*10^-4; //new diffusion coefficient
pt=pt_2*1.013*10^5; //new total pressure
Na=Dab*pt*log((1-ya2)/(1-ya1))/(z*R*T); //diffusion flux in kmol/m^2*s
printf("\n diffusion flux when pressure is increased to 10atm :%f *10^-5 kmol/m^2*s ",Na/10^-5);
printf("\n \n so the rate of diffusion remains same on increasing the pressure");
//end
|
