cantera/src/tpx/Sub.cpp
2012-07-18 18:32:29 +00:00

765 lines
18 KiB
C++

/*
* The Substance class
* D. Goodwin, Caltech Nov. 1996
*/
#include "cantera/tpx/Sub.h"
#include <math.h>
#include <fstream>
#include <stdio.h>
using std::string;
namespace tpx
{
static string fp2str(double x, string fmt="%g")
{
char buf[30];
sprintf(buf, fmt.c_str(), x);
return string(buf);
}
/*
static string int2str(int n, string fmt="%d") {
char buf[30];
sprintf(buf, fmt.c_str(), n);
return string(buf);
}
*/
string TPX_Error::ErrorMessage = "";
string TPX_Error::ErrorProcedure = "";
string errorMsg(int flag)
{
switch (flag) {
case NoConverge:
return "no convergence";
case GenError:
return "general error";
case InvalidInput:
return "invalid input";
case TempError:
return "temperature error";
case PresError:
return "pressure error";
default:
return "(unknown error)";
}
}
//-------------- Public Member Functions --------------
Substance::Substance() :
T(Undef),
Rho(Undef),
Tslast(Undef),
Rhf(Undef),
Rhv(Undef),
Pst(Undef),
Err(0),
m_energy_offset(0.0),
m_entropy_offset(0.0),
kbr(0)
{
}
/// Pressure [Pa]. If two phases are present, return the
/// saturation pressure; otherwise return the pressure
/// computed directly from the underlying eos.
double Substance::P()
{
double ppp = (TwoPhase() ? Ps() : Pp());
return (Err ? Undef : ppp);
}
const double DeltaT = 0.000001;
/// The derivative of the saturation pressure
/// with respect to temperature.
double Substance::dPsdT()
{
double ps1, tsave, dpdt;
tsave = T;
ps1 = Ps();
set_T(T + DeltaT);
dpdt = (Ps() - ps1)/DeltaT;
set_T(tsave);
return (Err ? Undef : dpdt);
}
/// true if a liquid/vapor mixture, false otherwise
int Substance::TwoPhase()
{
if (T >= Tcrit()) {
return 0;
}
update_sat();
return ((Rho < Rhf) && (Rho > Rhv) ? 1 : 0);
}
/// Vapor fraction.
/// If T >= Tcrit, 0 is returned for v < Vcrit, and 1 is
/// returned if v > Vcrit.
double Substance::x()
{
double xx, vv, vl;
if (T >= Tcrit()) {
return (1.0/Rho < Vcrit() ? 0.0 : 1.0);
} else {
update_sat();
if (Rho <= Rhv) {
xx = 1.0;
} else if (Rho >= Rhf) {
xx = 0.0;
} else {
vv = 1.0/Rhv;
vl = 1.0/Rhf;
xx = (1.0/Rho - vl)/(vv - vl);
}
return (Err ? Undef : xx);
}
}
/// Saturation temperature at pressure p.
double Substance::Tsat(double p)
{
double Tsave, p_here, dp, dt, dpdt, dta,
dtm, tsat;
if (Err || (p <= 0.0) || (p > Pcrit())) {
throw TPX_Error("Substance::Tsat","illegal pressure value");
set_Err(PresError);
return Undef;
}
int LoopCount = 0;
double tol = 1.e-6*p;
Tsave = T;
if (T < Tmin()) {
T = 0.5*(Tcrit() - Tmin());
}
if (T >= Tcrit()) {
T = 0.5*(Tcrit() - Tmin());
}
do {
if (Err) {
break;
}
if (T > Tcrit()) {
T = Tcrit() - 0.001;
}
if (T < Tmin()) {
T = Tmin() + 0.001;
}
p_here = Ps();
dpdt = dPsdT();
dp = p - p_here;
dt = dp/dpdt;
dta = fabs(dt);
dtm = 0.1*T;
if (dta > dtm) {
dt = dt*dtm/dta;
}
T = T + dt;
LoopCount++;
if (LoopCount > 100) {
T = Tsave;
set_Err(NoConverge);
return Undef;
}
} while (fabs(dp) > tol);
tsat = T;
T = Tsave;
return (Err ? Undef : tsat);
}
// absolute tolerances
static const double TolAbsH = 0.0001; // J/kg
static const double TolAbsU = 0.0001;
static const double TolAbsS = 1.e-7;
static const double TolAbsP = 0.000; // Pa
static const double TolAbsV = 1.e-8;
static const double TolAbsT = 1.e-3;
static const double TolRel = 3.e-8;
void Substance::Set(int XY, double x0, double y0)
{
double temp;
clear_Err(); // clear error flag
/* if inverted (PT) switch order and change sign of XY (TP = -PT) */
if (XY < 0) {
double tmp = x0;
x0 = y0;
y0 = tmp;
XY *= -1;
}
switch (XY) {
case TV:
set_T(x0);
set_v(y0);
break;
case HP:
if (Lever(Pgiven, y0, x0, EvalH)) {
return;
}
set_xy(EvalH, EvalP, x0, y0, TolAbsH, TolAbsP, TolRel, TolRel);
break;
case SP:
if (Lever(Pgiven, y0, x0, EvalS)) {
return;
}
set_xy(EvalS, EvalP, x0, y0, TolAbsS, TolAbsP, TolRel, TolRel);
break;
case PV:
if (Lever(Pgiven, x0, y0, EvalV)) {
return;
}
set_xy(EvalP, EvalV, x0, y0, TolAbsP, TolAbsV, TolRel, TolRel);
break;
case TP:
if (x0 < Tcrit()) {
set_T(x0);
if (y0 < Ps()) {
Set(TX, x0, Vapor);
} else {
Set(TX, x0, Liquid);
}
} else {
set_T(x0);
}
set_xy(EvalT, EvalP, x0, y0, TolAbsT, TolAbsP, TolRel, TolRel);
break;
case UV:
set_xy(EvalU, EvalV, x0, y0, TolAbsU, TolAbsV, TolRel, TolRel);
break;
case ST:
if (Lever(Tgiven, y0, x0, EvalS)) {
return;
}
set_xy(EvalS, EvalT, x0, y0, TolAbsS, TolAbsT, TolRel, TolRel);
break;
case SV:
set_xy(EvalS, EvalV, x0, y0, TolAbsS, TolAbsV, TolRel, TolRel);
break;
case UP:
if (Lever(Pgiven, y0, x0, EvalU)) {
return;
}
set_xy(EvalU, EvalP, x0, y0, TolAbsU, TolAbsP, TolRel, TolRel);
break;
case VH:
set_xy(EvalV, EvalH, x0, y0, TolAbsV, TolAbsH, TolRel, TolRel);
break;
case TH:
set_xy(EvalT, EvalH, x0, y0, TolAbsT, TolAbsH, TolRel, TolRel);
break;
case SH:
set_xy(EvalS, EvalH, x0, y0, TolAbsS, TolAbsH, TolRel, TolRel);
break;
case PX:
temp = Tsat(x0);
if ((y0 >= 0.0) && (y0 <= 1.0) && (temp < Tcrit())) {
set_T(temp);
update_sat();
Rho = 1.0/((1.0 - y0)/Rhf + y0/Rhv);
} else {
set_Err(InvalidInput);
}
break;
case TX:
if ((y0 >= 0.0) && (y0 <= 1.0) && (x0 < Tcrit())) {
set_T(x0);
update_sat();
Rho = 1.0/((1.0 - y0)/Rhf + y0/Rhv);
} else {
set_Err(InvalidInput);
}
break;
default:
set_Err(InvalidInput);
}
if (Err) {
T = Undef;
Rho = Undef;
Tslast = Undef;
Rhf = Undef;
Rhv = Undef;
}
}
//------------------ Protected and Private Functions -------------------
void Substance::set_Rho(double r0)
{
if (r0 > 0.0) {
Rho = r0;
} else {
set_Err(InvalidInput);
}
}
void Substance::set_T(double t0)
{
if ((t0 >= Tmin()) && (t0 <= Tmax())) {
T = t0;
} else {
throw TPX_Error("Substance::set_T",
"illegal temperature value "+fp2str(t0));
set_Err(TempError);
}
}
void Substance::set_v(double v0)
{
if (v0 > 0) {
Rho = 1.0/v0;
} else {
throw TPX_Error("Substance::set_v",
"negative specific volume: "+fp2str(v0));
set_Err(InvalidInput);
}
}
double Substance::Ps()
{
if (T < Tmin() || T > Tcrit()) {
throw TPX_Error("Substance::Ps",
"illegal temperature value "+fp2str(T));
set_Err(TempError);
return Undef;
}
update_sat();
return Pst;
}
// update saturated liquid and vapor densities and saturation pressure
void Substance::Set_meta(double phase, double pp)
{
if (phase == Liquid) {
Rho = ldens(); // trial value = liquid dens
} else {
Rho = pp*MolWt()/(8314.0*T); // trial value = ideal gas
}
set_TPp(T, pp);
}
void Substance::update_sat()
{
if ((T != Tslast) && (T < Tcrit())) {
double Rho_save = Rho;
double gf, gv, dg, dp, dlp, psold;
double pp = Psat();
double lps = log(pp);
// trial value = Psat from correlation
int i;
for (i = 0; i<20; i++) {
if (i==0) {
Rho = ldens(); // trial value = liquid density
} else {
Rho = Rhf;
}
set_TPp(T,pp);
Rhf = Rho; // sat liquid density
gf = hp() - T*sp();
if (i==0) {
Rho = pp*MolWt()/(8314.0*T); // trial value = ideal gas
} else {
Rho = Rhv;
}
set_TPp(T,pp);
Rhv = Rho; // sat vapor density
gv = hp() - T*sp();
dg = gv - gf;
if (Rhv > Rhf) {
std::swap(Rhv, Rhf);
dg = - dg;
}
if (fabs(dg) < 0.001 && Rhf > Rhv) {
break;
}
dp = dg/(1.0/Rhv - 1.0/Rhf);
psold = pp;
if (fabs(dp) > pp) {
dlp = dg/(pp*(1.0/Rhv - 1.0/Rhf));
lps -= dlp;
pp = exp(lps);
} else {
pp -= dp;
lps = log(pp);
}
if (pp > Pcrit()) {
pp = psold + 0.5*(Pcrit() - psold);
lps = log(pp);
} else if (pp < 0.0) {
pp = psold/2.0;
lps = log(pp);
}
}
if (Rhf <= Rhv) {
throw TPX_Error("Substance::update_sat",
"wrong root found for sat. liquid or vapor at P = "+fp2str(pp));
}
if (i >= 20) {
Pst = Undef;
Rhv = Undef;
Rhf = Undef;
Tslast = Undef;
throw TPX_Error("substance::update_sat","no convergence");
set_Err(NoConverge);
} else {
Pst = pp;
Tslast = T;
}
Rho = Rho_save;
}
}
double Substance::vprop(int ijob)
{
switch (ijob) {
case EvalH:
return hp();
case EvalS:
return sp();
case EvalU:
return up();
case EvalV:
return vp();
case EvalP:
return Pp();
default:
return Undef;
}
}
int Substance::Lever(int itp, double sat, double val, int ifunc)
{
/*
* uses lever rule to set state in the dome. Returns 1 if in dome,
* 0 if not, in which case state not set.
*/
double Valf, Valg, Tsave, Rhosave, xx, vv, psat;
Tsave = T;
Rhosave = Rho;
if (itp == Tgiven) {
if (sat >= Tcrit()) {
return 0;
}
set_T(sat);
psat = Ps();
} else if (itp == Pgiven) {
if (sat >= Pcrit()) {
return 0;
}
psat = sat;
T = Tsat(psat);
if (T == Undef) {
Err = 0;
T = Tsave;
Rho = Rhosave;
return 0;
}
} else {
throw TPX_Error("Substance::Lever","general error");
set_Err(GenError);
return GenError;
}
Set(TX, T, Vapor);
Valg = vprop(ifunc);
Set(TX, T, Liquid);
Valf = vprop(ifunc);
if (Err) {
return Err;
} else if ((val >= Valf) && (val <= Valg)) {
xx = (val - Valf)/(Valg - Valf);
vv = (1.0 - xx)/Rhf + xx/Rhv;
set_v(vv);
return 1;
} else {
T = Tsave;
Rho = Rhosave;
return 0;
}
}
void Substance::set_xy(int ifx, int ify, double X, double Y,
double atx, double aty,
double rtx, double rty)
{
double v_here, t_here, dv, dt, dxdt, dydt, dxdv, dydv,
det, x_here, y_here, dvm, dtm, dva, dta;
double Xa, Ya, err_x, err_y;
double dvs1 = 2.0*Vcrit();
double dvs2 = 0.7*Vcrit();
int LoopCount = 0;
double v_save = 1.0/Rho;
double t_save = T;
if (Err) {
return;
}
if ((T == Undef) && (Rho == Undef)) { // new object, try to pick
Set(TV,Tcrit()*1.1,Vcrit()*1.1); // "reasonable" starting point
t_here = T;
v_here = 1.0/Rho;
} else if (Rho == Undef) { // new object, try to pick
Set(TV,T,Vcrit()*1.1); // "reasonable" starting point
t_here = T;
v_here = 1.0/Rho;
} else {
v_here = v_save;
t_here = t_save;
}
Xa = fabs(X);
Ya = fabs(Y);
// loop
do {
if (Err) {
break;
}
x_here = prop(ifx);
y_here = prop(ify);
err_x = fabs(X - x_here);
err_y = fabs(Y - y_here);
if ((err_x < atx + rtx*Xa) && (err_y < aty + rty*Ya)) {
break;
}
/* perturb t */
dt = 0.001*t_here;
if (t_here + dt > Tmax()) {
dt *= -1.0;
}
/* perturb v */
dv = 0.001*v_here;
if (v_here <= Vcrit()) {
dv *= -1.0;
}
/* derivatives with respect to T */
Set(TV, t_here + dt, v_here);
dxdt = (prop(ifx) - x_here)/dt;
dydt = (prop(ify) - y_here)/dt;
/* derivatives with respect to v */
Set(TV, t_here, v_here + dv);
dxdv = (prop(ifx) - x_here)/dv;
dydv = (prop(ify) - y_here)/dv;
det = dxdt*dydv - dydt*dxdv;
dt = ((X - x_here)*dydv - (Y - y_here)*dxdv)/det;
dv = ((Y - y_here)*dxdt - (X - x_here)*dydt)/det;
dvm = 0.2*v_here;
if (v_here < dvs1) {
dvm *= 0.5;
}
if (v_here < dvs2) {
dvm *= 0.5;
}
dtm = 0.1*t_here;
dva = fabs(dv);
dta = fabs(dt);
if (dva > dvm) {
dv *= dvm/dva;
}
if (dta > dtm) {
dt *= dtm/dta;
}
v_here += dv;
t_here += dt;
if (t_here >= Tmax()) {
t_here = Tmax() - 0.001;
} else if (t_here <= Tmin()) {
t_here = Tmin() + 0.001;
}
if (v_here <= 0.0) {
v_here = 0.0001;
}
Set(TV, t_here, v_here);
LoopCount++;
if (LoopCount > 200) {
throw TPX_Error("Substance::set_xy","no convergence");
set_Err(NoConverge);
break;
}
} while (1);
}
double Substance::prop(int ijob)
{
double xx, pp, lp, vp, Rho_save;
if (ijob == EvalP) {
return P();
}
if (ijob == EvalT) {
return T;
}
xx = x();
if ((xx > 0.0) && (xx < 1.0)) {
Rho_save = Rho;
Rho = Rhv;
vp = vprop(ijob);
Rho = Rhf;
lp = vprop(ijob);
pp = (1.0 - xx)*lp + xx*vp;
Rho = Rho_save;
return pp;
} else {
return vprop(ijob);
}
}
static const double ErrP = 1.e-7;
static const double Big = 1.e30;
void Substance::BracketSlope(double Pressure)
{
if (kbr == 0) {
dv = (v_here < Vcrit() ? -0.05*v_here : 0.2*v_here);
if (Vmin > 0.0) {
dv = 0.2*v_here;
}
if (Vmax < Big) {
dv = -0.05*v_here;
}
} else {
double dpdv = (Pmax - Pmin)/(Vmax - Vmin);
v_here = Vmax;
P_here = Pmax;
dv = dvbf*(Pressure - P_here)/dpdv;
dvbf = 0.5*dvbf;
}
}
void Substance::set_TPp(double Temp, double Pressure)
{
kbr = 0;
dvbf = 1.0;
Vmin = 0.0;
Vmax = Big;
Pmin = Big;
Pmax = 0.0;
double dvs1 = 2.0*Vcrit();
double dvs2 = 0.7*Vcrit();
int LoopCount = 0;
double v_save = 1.0/Rho;
set_T(Temp);
v_here = vp();
// loop
while (P_here = Pp(),
fabs(Pressure - P_here) >= ErrP* Pressure || LoopCount == 0) {
if (P_here < 0.0) {
BracketSlope(Pressure);
} else {
dv = 0.001*v_here;
if (v_here <= Vcrit()) {
dv *= -1.0;
}
Set(TV, Temp, v_here+dv);
double dpdv = (Pp() - P_here)/dv;
if (dpdv > 0.0) {
BracketSlope(Pressure);
} else {
if ((P_here > Pressure) && (v_here > Vmin)) {
Vmin = v_here;
} else if ((P_here < Pressure) && (v_here < Vmax)) {
Vmax = v_here;
}
if (v_here == Vmin) {
Pmin = P_here;
}
if (v_here == Vmax) {
Pmax = P_here;
}
if (Vmin >= Vmax) {
throw TPX_Error("Substance::set_TPp","Vmin >= Vmax");
set_Err(GenError);
} else if ((Vmin > 0.0) && (Vmax < Big)) {
kbr = 1;
}
dvbf = 1.0;
if (dpdv == 0.0) {
dvbf = 0.5;
BracketSlope(Pressure);
} else {
dv = (Pressure - P_here)/dpdv;
}
}
}
double dvm = 0.2*v_here;
if (v_here < dvs1) {
dvm *= 0.5;
}
if (v_here < dvs2) {
dvm *= 0.5;
}
if (kbr != 0) {
double vt = v_here + dv;
if ((vt < Vmin) || (vt > Vmax)) {
dv = Vmin + (Pressure - Pmin)*(Vmax - Vmin)/(Pmax - Pmin) - v_here;
}
}
double dva = fabs(dv);
if (dva > dvm) {
dv *= dvm/dva;
}
v_here += dv;
if (dv == 0.0) {
throw TPX_Error("Substance::set_TPp","dv = 0 and no convergence");
set_Err(NoConverge);
return;
}
Set(TV, Temp, v_here);
LoopCount++;
if (LoopCount > 100) {
Set(TV, Temp, v_save);
throw TPX_Error("Substance::set_TPp",string("no convergence for ")
+"P* = "+fp2str(Pressure/Pcrit())+". V* = "
+fp2str(v_save/Vcrit()));
set_Err(NoConverge);
return;
}
}
Set(TV, Temp,v_here);
}
}