clear; clc; // Illustration 4.5 // Page: 245 printf('Illustration 4.5 - Page: 245\n\n'); // solution //*****Data*****// // a-chloroform b-water c-air T = 298; // [K] Dv = 1; // [vessel diameter, m] Vb = 10; // [kg/s] ca = 240*10^-6; // [gram/l] xr = 0.9; // [chloroform which is to be removed] m = 220; Ds = 0.5; // [diameter of sparger, m] no = 90; // [number of orifices] Do = 3*10^-3; // [diameter of orifice, m] nm = 0.6; // [mechanical efficiency] rowb = 1000; // [kg/cubic m] R = 8.314; Mc = 29; // [gram/mole] Mb = 18; // [gram/mole] g = 9.8; // [square m/s] //*****// Vair = 0.1; // [kg/s as calculated in chapter 3] mg = Vair/no; // [mass flow rate through each orifice, kg/s] ug = 1.8*10^-5; // [kg/m.s] Reo = 25940; // [Renoylds number] // From equ. 4.20 dp = 0.0071*Reo^-0.05; // [m] // Since the water column height is not known, therefore an iterative procedure must be implemented. // Assuming column height, Z = 0.5 m Z = 0.5; // [m] // For Z = 0.5 m rowl = 1000; // [kg/cubic m] Ps = 101.3; // [kPa] Po = Ps + (1000*9.8*0.5/1000); // [kPa] Pavg = (Po+Ps)/2; // [kPa] rowg = Pavg*Mc/(R*T); // [kg/cubic m] area = %pi*Dv^2/4; // [square m] vg = Vair/(rowg*area); // [m/s] // In this case rowl = rowg and sigma = sigmaAW // From equation 4.22 // Vg = vg // vg/vs = 0.182 vs = vg/0.182; // [m/s] vl = -Vb/(rowl*area); // [negative because water flows downward, m/s] // From equ 4.21 deff('[y] = f12(phig)','y = vs - (vg/phig)-(-vl/(1-phig))'); phig = fsolve(0.1,f12); // Now in this case S = vl/(1-phig); // Value of 'S' comes out to be less than 0.15 m/s // Therefore dp = (dp^3*Po/Pavg)^(1/3); // [m] // From equ 4.23 a = 6*phig/dp; // [m^-1] // Now we calculate diffusivity of chloroform Vba = 88.6; // [cubic cm/mole] u = 0.9*10^-3; // [Pa-s] e = (9.58/(Vba)-1.12); // From equation 1.53 Dl = 1.25*10^-8*((Vba)^-0.19 - 0.292)*T^1.52*(u*10^3)^e; // [square cm/s] // And Schmidt number is Scl = 833; // [Schmidt Number] // Now we calculate dp*g^(1/3)/Dl^(2/3) = J J = dp*g^(1/3)/(Dl*10^-4)^(2/3) Reg = dp*vs*rowl/u; // [Gas bubble Renoylds number] // From equ 4.25 Shl = 2 + 0.0187*Reg^0.779*Scl^0.546*J^0.116; // For dilute solution xbm = 1 or c = 55.5 kmole/cubic m // Then for Nb = 0 c = 55.5; // [kmole/cubic m] kx = Shl*c*Dl*10^-4/dp; // [kmole/square m.s] mtc = kx*a; // [kmole/cubic m.s] L = Vb/Mb; // [kmole/s] Gmx = L/area; // [kmole/square m.s] V = Vair/Mc; // [kmole/s] A = L/(m*V); // [absorption factor] // From equ 4.28 // For, xin/xout = x = 10 x = 10; Z = (Gmx/(kx*a*(1-A)))*log(x*(1-A)+A); // With this new estimated Z ,we again calculate average pressure in the // column of water Po1 = 110.1; // [kPa] Pavg1 = 105.7; // [kPa] rowg1 = Pavg1*Mc/(R*T); // Now value of rowg1 obtained is very close to value used in the first // iteration. Therefore on three iteractions we achieve a value of 'Z' Z1 = 0.904; // [m] rowgo = Po1*Mc/(R*T); // [kg/cubic m] vo1 = 4*mg/(%pi*Do^2*rowgo); // [m/s] // Therefore, vo1^2/(2*gc) = F gc = 1; F = vo1^2/(2*gc); // [J/kg] // And R*T*log(Po/Ps)/Mc = G G = R*T*1000*log(Po1/Ps)/Mc; // [J/kg] Zs = 0 // And (Z1-Zs)*g/gc = H H = (Z1-Zs)*g/gc; // [J/kg] // From equ 4.27 W = F+G+H; // [J/kg] // Now the air compressor power is W1 = W*Vair*10^-3/nm; // [kW] printf("The depth of the water column required to achieve the specified 90percent removal efficiency is %f m\n\n",Z1); printf("The power required to operate the air compressor is %f kW\n\n",W1);