I would like to solve {na, nb, nw, T, P} at z=20 given these differential equations and initial conditions where these values are given
d := .686;
L := 6.73;
U := 812;
Te := 800;
eP := .6;
OS := .45;
Dp := .0046;
nao := 1.345;
nbo := 1.412;
mwa := .064;
mwb := .032;
mwi := .014;
G := 4*(nao*mwa + nbo*mwb + ni*mwi)/(Pi*d^2);
dens := (4*G*P[z])/(Pi*d*d*8.314*T[z]*(na[z] + nb[z] + nw[z] + ni));
H298 := 2*(-94470) - (2*(-70950));
aa := 5.697;
ab := 6.713;
aw := 12.13;
ba := 0.016;
bb := -0.0000000879;
bw := .00812;
ya := -0.00001185;
yb := .00000417;
yw := 0;
da := .000000003172;
db := -.000000002544;
dw := 0;
H[T[z]] := (H298 ) + (2*aw - 2*aa - 2*ab)*(T[z] -
298) + ((2*bw - 2*ba - bb)/2)*(T[z]^2 -
298^2) + ((2*yw - 2*ya - yb)/3)*(T[z]^3 -
298^3) + ((2*dw - 2*da - db)/4)*(T[z]^4 - 298^4)
NDSolve[{na'[z] == (-2*((Pi*d*d)/4))*r, nb'[z] == (-(Pi*d*d)/4)*r,
nw'[z] == 2*((Pi*d*d)/4)*r,
T'[z] == 1*((Pi*d*U*(Te - T[z])) - (((Pi*d*d)/4)*r*H))/(na[z]*Cpa +
nb[z]*Cpb + nw[z]*Cpw + ni*Cpi),
P'[z] == -1*((1 - eP)/
eP^3)*(G^2/(dens*OS*Dp*9.81))*(((150*(1 - eP)*.32)/(OS*Dp*G)) +
1.75), na[0] == 1.345, nb[0] == 1.412, nw[0] == 0,
T[0] == 727.6, P[0] == 2.5}, {na, nb, nw, T, P}, {z, 20}]
is what i thought would work but it is not
Attachments:
