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/*
freesteam - IAPWS-IF97 steam tables library
Copyright (C) 2004-2009 John Pye
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#define FREESTEAM_BUILDING_LIB
#include "steam.h"
#include "region.h"
#include "zeroin.h"
#include "b23.h"
#include "bounds.h"
#include "backwards.h"
#include <stdlib.h>
#include <assert.h>
#include <math.h>
int freesteam_bounds_Ts(double T, double s, int verbose){
double smax;
#define BOUND_WARN(MSG) \
if(verbose){\
fprintf(stderr,"%s (%s:%d): WARNING " MSG " (T = %g, s = %g kJ/kgK)\n"\
,__func__,__FILE__,__LINE__,T,s/1e3);\
}
if(T < IAPWS97_TMIN){
BOUND_WARN("T < TMIN");
return 1;
}
if(T > IAPWS97_TMAX + 1e-5){
BOUND_WARN("T > TMAX");
return 2;
}
smax = freesteam_region2_s_pT(0.,T);
if(s > smax){
BOUND_WARN("s > smax");
return 3;
}
if(T <= REGION1_TMAX){
double smin = freesteam_region1_s_pT(IAPWS97_PMAX,T);
if(s < smin){
BOUND_WARN("s < smin (region 1)");
return 4;
}
}else if(T > freesteam_b23_T_p(IAPWS97_PMAX)){
double smin = freesteam_region2_s_pT(IAPWS97_PMAX,T);
if(s < smin){
BOUND_WARN("s < smin (region 2)");
return 4;
}
}else{
/* region 3, need to iterate */
double smin;
SteamState S = freesteam_bound_pmax_T(T);
smin = freesteam_s(S);
if(s < smin){
BOUND_WARN("s < smin (region 3)");
return 4;
}
}
return 0;
#undef BOUND_WARN
}
int freesteam_region_Ts(double T, double s){
double p23, s23, psat, Tsat;
if(T <= REGION1_TMAX){
double p = freesteam_region4_psat_T(T);
double sf = freesteam_region1_s_pT(p,T);
double sg = freesteam_region2_s_pT(p,T);
if(s <= sf){
return 1;
}
if(s >= sg){
return 2;
}
return 4;
}
/* an optimisation, using known range of s values on b23 IAPWS97 sect 4, p 5 */
p23 = freesteam_b23_p_T(T);
s23 = freesteam_region2_s_pT(p23,T);
if(s >= s23){
return 2;
}
/* that leaves region 4 (near the C.P.) or region 3 */
/* FIXME need this hack to make low-s part of region behave correctly */
if(s < 3.7e3)return 3;
/* FIXME iterate to improve location of saturation curve? */
psat = freesteam_region3_psat_s(s);
Tsat = freesteam_region4_Tsat_p(psat);
if(T > Tsat)return 3;
return 4;
}
typedef struct{
double T, s, psat;
} SolveTSData;
#define D ((SolveTSData *)user_data)
static ZeroInSubjectFunction Ts_region1_fn, Ts_region2_fn, Ts_region4_fn1, Ts_region4_fn2;
double Ts_region1_fn(double p, void *user_data){
return D->s - freesteam_region1_s_pT(p, D->T);
}
double Ts_region2_fn(double p, void *user_data){
return D->s - freesteam_region2_s_pT(p, D->T);
}
double Ts_region3_fn(double rho, void *user_data){
return D->s - freesteam_region3_s_rhoT(rho, D->T);
}
double Ts_region4_fn1(double x, void *user_data){
/* for region 4 where T < REGION1_TMAX */
double sf = freesteam_region1_s_pT(D->psat,D->T);
double sg = freesteam_region2_s_pT(D->psat,D->T);
return D->s - (sf + x*(sg-sf));
}
double Ts_region4_fn2(double x, void *user_data){
/* for region 4 where T > REGION1_TMAX */
double rhof = freesteam_region4_rhof_T(D->T);
double rhog = freesteam_region4_rhog_T(D->T);
double sf = freesteam_region3_s_rhoT(rhof,D->T);
double sg = freesteam_region3_s_rhoT(rhog,D->T);
/* TODO: iteratively improve guess with forward fns*/
return D->s - (sf + x*(sg-sf));
}
#undef D
SteamState freesteam_set_Ts(double T, double s){
double lb, ub, tol, sol = 0, err;
int region;
SolveTSData D = {T, s, 0};
region = freesteam_region_Ts(T,s);
switch(region){
case 1:
lb = IAPWS97_PTRIPLE;
ub = IAPWS97_PMAX;
tol = 1e-9; /* ??? */
zeroin_solve(&Ts_region1_fn, &D, lb, ub, tol, &sol, &err);
assert(fabs(err/sol)<tol);
return freesteam_region1_set_pT(sol,T);
case 2:
lb = 0.;
ub = IAPWS97_PMAX;
if(T > REGION1_TMAX && T < freesteam_b23_T_p(IAPWS97_PMAX)){
ub = freesteam_b23_p_T(T);
}
tol = 1e-9; /* ??? */
zeroin_solve(&Ts_region2_fn, &D, lb, ub, tol, &sol, &err);
return freesteam_region2_set_pT(sol,T);
case 3:
lb = 0;
ub = 1000;
tol = 1e-9; /* ??? */
zeroin_solve(&Ts_region3_fn, &D, lb, ub, tol, &sol, &err);
assert(fabs(err/sol)<tol);
return freesteam_region3_set_rhoT(sol,T);
case 4:
lb = 0.;
ub = 1.;
tol = 1e-12; /* ??? */
D.psat = freesteam_region4_psat_T(T);
zeroin_solve(
(T < REGION1_TMAX ? &Ts_region4_fn1 : &Ts_region4_fn2)
, &D, lb, ub, tol, &sol, &err
);
assert(fabs(err)<tol);
return freesteam_region4_set_Tx(T,sol);
default:
/* ??? */
fprintf(stderr,"%s (%s:%d): Region '%d' not implemented\n",__func__,__FILE__,__LINE__,region);
exit(1);
}
}
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