Help in solving the equation of van der vusse reactor

dx=(u1)*(x0-x)-(k10*exp(E1/t+273.15)*x)-(k30*exp(E3/t+273.15)*x^2);

dy=-((u1)*y)+(k10*exp(E1/t+273.15)*x)-(k20*exp(E2/t+273.15)*y);

dt=(u1*(t0-t))-(k10*exp(E1/t+273.15)*x*DHab+k20*exp(E2/t+273.15)*y*DHbc+k30*exp(E3/t+273.15)*(x^2)*DHad)/(P*Cp)+ ((Kw*Ar)/(P*Cp))*(t-tk);

dtk=((Fck*Cpk)*(tk0-tk)+(Kw*Ar)*(t-tk))/(Mk*Cpk);

% param Vr=10; E1=9758.3; %(K) E2=E1; %(K)

        E3=-8560;           %(k)
        DHab=4.2;            %(KJ/MOL A)
        DHbc=-11.0;          %(KJ/MOL A)
        DHad=-41.85;         %(KJ/MOL A)
        P=0.9342;           %(KG/L)
        Cp=3.01;            %(KJ/KG K)
        Kw=432;             %(KJ/h M^2 K)
        Ar=0.215;           %(M^2)
        Mk=5;               %(KG) 
        Cpk=2.0;            %(KJ/KG K)
        x0=5.1;           
        t0=60;             
        tk0=110;
        y0=0;  
        Fck=10.52;          %(KG/H)             
        k10=1.287e+12;
        k20=1.287e+12;
        k30=9.043e+9;

       in stat sapce i wantknow 
x=!
y=!
t=!
tk=!
 help me plz
[x,y,t,tk]=solve('(u1)*(x0-x)-(k10*exp(E1/t+273.15)*x)-(k30*exp(E3/t+273.15)*x^2)=0','-((u1)*y)+(k10*exp(E1/t+273.15)*x)-(k20*exp(E2/t+273.15)*y)=0','(u1*(t0-t))-(k10*exp(E1/t+273.15)*x*DHab+k20*exp(E2/t+273.15)*y*DHbc+k30*exp(E3/t+273.15)*(x^2)*DHad)/(P*Cp)+ ((Kw*Ar)/(P*Cp))*(t-tk)=0','((Fck*Cpk)*(tk0-tk)+(Kw*Ar)*(t-tk))/(Mk*Cpk)=0')

Warning: Explicit solution could not be found. > In solve at 81 In Untitled14 at 31

x =

[ empty sym ]

y =

     []

t =

     []

tk =

     []

Answer 1

[bym]

You need some parentheses, for example

k10*exp(E1/t+273.15)*x  %<-- your expression

should be

k10*exp(E1/(t+273.15))*x

fix all occurrences and see what you get

[azou]

thx for answer but

when i try this

syms u1 x0 x k10 E1 z k k30 E3 y k20 z0 DHad DHbc DHab P Cp Vr Fck Kw Mk Ar l0 l

% % %=====================================

S=solve('u1*(x0-x)-(k10*exp(E1/(z+k))*x)-(k30*exp(E3/(z+k))*x^2)=0','-(u1*y)+(k10*exp(E1/(z+k))*x)-(k20*exp(E2/(z+k))*y)=0','(u1*(z0-z))-((k10*exp(E1/(z+k))*x*DHab)+(k20*exp(E2/(z+k))*y*DHbc)+(k30*exp(E3/(z+k))*(x^2)*DHad))/(P*Cp)+ (u2/(P*Cp*Vr))=0','((Fck*Cpk)*(l0-l)+(Kw*Ar)*(z-l))/(Mk*Cpk)=0')

result is

S =

x: [1x1 sym]

x0: [1x1 sym]

y: [1x1 sym]

z: [1x1 sym]

if i change S =[x,y,z,l] or S=[l ,x,z,y] is same not i want !!!!

[bym]

what are u1 u2 k z0

[Walter Roberson]

What does asking for S.x show?