how to define the range with variable

h_H2 = 0;
h_O2 = 0;
h_H2O = -241827;
s_H2 = 130.59;
s_O2 = 205.14;
s_H2O = 188.83;
T_ref = 298;
T = 293:1173;
n = 2;
F = 96487; 
S = -163.25;
delH = (h_H2O + (143.05-58.04*(T.^0.25)+8.2751*(T.^0.5)-0.036989*T)*(T-T_ref)) - (1/2)*(h_H2 + (56.505-22222.6*(T.^(-0.75))+116500*(T.^(-1))-560700*(T.^(-1.5)))*(T-T_ref)) - (1/2)*(h_O2+(37.432+2.0102*(10.^(-5))*(T.^1.5)-178570*(T.^(-1.5))+2368800*(T.^(-2)))*(T-T_ref));
plot(T,delH)

it works if I use a value for T, but if I want to use the range of the T, it gives me error.

Answer 1

[KSSV]

You need to use elelement by element (.*) multiplication as well .

h_H2 = 0;
h_O2 = 0;
h_H2O = -241827;
s_H2 = 130.59;
s_O2 = 205.14;
s_H2O = 188.83;
T_ref = 298;
T = 293:1173;
n = 2;
F = 96487; 
S = -163.25;
delH = (h_H2O + (143.05-58.04*(T.^0.25)+8.2751*(T.^0.5)-0.036989*T).*(T-T_ref)) .....
      - (1/2)*(h_H2 + (56.505-22222.6*(T.^(-0.75))+116500*(T.^(-1))-560700.*(T.^(-1.5))).*(T-T_ref)) .....
      - (1/2)*(h_O2+(37.432+2.0102*(10.^(-5)).*(T.^1.5)-178570.*(T.^(-1.5))+2368800.*(T.^(-2))).*(T-T_ref));
plot(T,delH)

[hai xia]

h_H2 = 0;

h_O2 = 0;

h_H2O = -241827;

s_H2 = 130.59;

s_O2 = 205.14;

s_H2O = 188.83;

T_ref = 298;

T = 293:1173;

n = 2;

F = 96487;

S = -163.25;

CpH2 = 56.505-22222.6*(T.^(-0.75))+116500*(T.^(-1))-560700*(T.^(-1.5));

CpO2 = 37.432+2.0102*(10.^(-5))*(T.^1.5)-178570*(T.^(-1.5))+2368800*(T.^(-2));

CpH2O = 143.05-58.04*(T.^0.25)+8.2751*T.^0.5-0.036989*T;

delH = (h_H2O + CpH2O.*(T-T_ref)) .....

- (1/2)*(h_H2 + CpH2.*(T-T_ref)) .....

- (1/2)*(h_O2 + CpO2.*(T-T_ref));

delS = (s_H2O + CpH2O.*log(T/T_ref)) .....

- (1/2)*(s_H2 + CpH2.*log(T/T_ref)) .....

- (1/2)*(s_O2 + CpO2.*log(T/T_ref));

delG = delH - (T_ref*delS);

Er = -delG/(n*F);

Sr = S/(n*F);

E = Er + Sr*(T - T_ref);

n = delG/delH;

plot(T,E)

So i make it successfully with your help.

One more quesiton, I am trying to get the efficieny n plot with temperature, under the current code, it does not show me a graph of efficiency changing with T.

Answer 2

[Torsten]

h_H2 = 0;
h_O2 = 0;
h_H2O = -241827;
s_H2 = 130.59;
s_O2 = 205.14;
s_H2O = 188.83;
T_ref = 298;
T = 293:1173;
n = 2;
F = 96487; 
S = -163.25;
delH = (h_H2O + (143.05-58.04*(T.^0.25)+8.2751*(T.^0.5)-0.036989*T).*(T-T_ref)) - (1/2)*(h_H2 + (56.505-22222.6*(T.^(-0.75))+116500*(T.^(-1))-560700*(T.^(-1.5))).*(T-T_ref)) - (1/2)*(h_O2+(37.432+2.0102*(10.^(-5))*(T.^1.5)-178570*(T.^(-1.5))+2368800*(T.^(-2))).*(T-T_ref));
plot(T,delH)