research/cantera
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Modified hydrogen equation of state to fix reference state

Browse source 
This makes the reference state for enthalpy and entropy agree with the
book from which the equation of state is taken (Reynolds, Thermodynamic
Properties in SI).
This commit is contained in:
Ray Speth 2012-05-07 18:20:23 +00:00
parent eb12c611db
commit 3af22be158
1 changed files with 29 additions and 56 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

85
src/tpx/Hydrogen.cpp
View file

@ -18,8 +18,8 @@ Tt = 13.8,
Pt = 7042.09,
R = 4124.299539,
Gamma = 1.008854772e-3,
u0 = 308901.4703,
s0 = 7759.186436,
u0 = 3.9275114e5,
s0 = 2.3900333e4,
T1 = 35,
T2 = 400,
alpha = 1.5814454428, //to be used with psat
@ -51,6 +51,7 @@ static const double Ghydro[]= {
-3.9144179e2, 5.8277696e2, 6.5409163e2, -1.8728847e2
};
double hydrogen::C(int i, double rt, double rt2)
{
switch (i) {
@ -150,42 +151,27 @@ double hydrogen::up()
double rt2 = rt*rt;
double rt3 = rt*rt2;
double egrho = exp(-Gamma*Rho*Rho);
double x, xlg;
double sum = u0;
double sum2, sum3;
for (int i=0; i<14; i++) {
sum += (C(i, rt, rt2) - T*Cprime(i, rt, rt2, rt3))*I(i, egrho);
}
// add \int c_{v,0} term
if (T <= T1) {
sum2 = Ghydro[0]*T;
} else {
if (T < T2) {
x = T/T1;
} else {
x = T2/T1;
}
xlg = log(x);
int i;
for (i=0, sum2=0.0; i<12; i++) {
sum2 += Ghydro[i]*icv(i, x, xlg);
}
sum2 *= T1;
sum2 += Ghydro[0]*T1;
if (T > T2) {
x = T/T2;
xlg = log(x);
for (i=0, sum3=0.0; i<5; i++) {
sum3 += Ghydro[i+12]*icv(i, x, xlg);
}
sum3 *= T2;
sum2 += sum3;
sum += Ghydro[0] * (std::min(T, T1) - To);
if (T > T1) {
double x = std::min(T, T2) / T1;
for (int i = 0; i < 12; i++) {
sum += Ghydro[i] * T1 * icv(i, x, log(x));
}
}
sum += sum2 + m_energy_offset;
return sum;
if (T > T2) {
double x = T/T2;
for (int i = 0; i < 5; i++) {
sum += Ghydro[i+12] * T2 * icv(i, x, log(x));
}
}
return sum + m_energy_offset;
}
double hydrogen::sp()
@ -194,40 +180,27 @@ double hydrogen::sp()
double rt2 = rt*rt;
double rt3 = rt*rt2;
double egrho = exp(-Gamma*Rho*Rho);
double x, xlg;
double sum = s0 - R*log(Rho);
double sum2, sum3;
for (int i=0; i<14; i++) {
sum -= Cprime(i, rt, rt2, rt3)*I(i, egrho);
}
// add \int c_{v,0}/T term
if (T <= T1) {
sum2 = Ghydro[0]*log(T);
} else {
if (T < T2) {
x = T/T1;
} else {
x = T2/T1;
}
xlg = log(x);
int i;
for (i=0, sum2 = 0.0; i<12; i++) {
sum2 += Ghydro[i]*pow(xlg, i+1)/(i+1);
}
sum2 += Ghydro[0]*log(T1);
if (T > T2) {
x = T/T2;
xlg = log(x);
for (i=0, sum3=0.0; i<5; i++) {
sum3 += Ghydro[i+12]*pow(xlg,i+1)/(i+1);
}
sum2 += sum3;
sum += Ghydro[0] * log(std::min(T, T1)/ To);
if (T > T1) {
double xlg = log(std::min(T, T2)/T1);
for (int i = 0; i < 12; i++) {
sum += Ghydro[i] / (i + 1) * pow(xlg, i+1);
}
}
sum += sum2 + m_entropy_offset;
return sum;
if (T > T2) {
double xlg = log(T/T2);
for (int i = 0; i < 5; i++) {
sum += Ghydro[i+12] / (i + 1) * pow(xlg, i+1);
}
}
return sum + m_entropy_offset;
}
double hydrogen::Pp()