2528df0f75
These changes make it unnecessary to copy header files around during the build process, which tends to confuse IDEs and debuggers. The headers which comprise Cantera's external C++ interface are now in the 'include' directory. All of the samples and demos are now in the 'samples' subdirectory.
349 lines
7.1 KiB
C++
349 lines
7.1 KiB
C++
/* FILE: Heptane.cpp
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* DESCRIPTION:
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* representation of substance Heptane
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* values and functions are from
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* "Thermodynamic Properties in SI" bu W.C. Reynolds
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* AUTHOR: jrh@stanford.edu: GCEP, Stanford University
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*
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*/
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#include "Heptane.h"
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#include <math.h>
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#include <string.h>
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namespace tpx
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{
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/*
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* Heptane constants
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*/
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static const double Tmn = 182.56; // [K] minimum temperature for which calculations are valid
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static const double Tmx = 1000.0; // [K] maximum temperature for which calculations are valid
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static const double Tc=537.68; // [K] critical temperature
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static const double Roc=197.60; // [kg/m^3] critical density
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static const double To=300; // [K] reference Temperature
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static const double R=82.99504; // [J/(kg*K)] gas constant (for this substance)
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static const double Gamma=9.611604E-6; // [??]
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static const double u0=3.4058439E5; // [] internal energy at To
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static const double s0=1.1080254E3; // [] entropy at To
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static const double Tp=400; // [K] ??
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static const double Pc=2.6199E6; // [Pa] critical pressure
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static const double M=100.20; // [kg/kmol] molar density
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/*
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* array Ahept is used by the function Pp
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*/
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static const double Ahept[]= {
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2.246032E-3,
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2.082990E2,
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5.085746E7,
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3.566396E9,
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1.622168E9,
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1.065237E-5,
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5.987922E-1,
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7.736602,
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1.929386E5,
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5.291379E-9
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};
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/*
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* array F is used by Psat
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*/
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static const double F[]= {
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-7.2298764,
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3.8607475E-1,
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-3.4216472,
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4.6274432E-1,
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-9.7926124,
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-4.2058094E1,
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7.5468678E1,
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3.1758992E2
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};
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/*
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* array D is used by the function ldens
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*/
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static const double D[]= {
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1.9760405E2,
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8.9451237E2,
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-1.1462908E3,
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1.7996947E3,
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-1.7250843E3,
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9.7088329E2
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};
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/*
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* array G is used by the function sp
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*/
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static const double G[]= {
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1.1925213E5,
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-7.7231363E2,
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7.4463527,
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-3.0888167E-3,
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0.0,
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0.0
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};
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/*
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* C returns a multiplier in each term of the sum
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* in P-2, used in conjunction with C in the function Pp
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* j is used to represent which of the values in the summation to calculate
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* j=0 is the second additive in the formula in reynolds
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* j=1 is the third...
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*/
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double Heptane::C(int j,double Tinverse, double T2inverse, double T3inverse, double T4inverse)
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{
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switch (j) {
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case 0 :
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return Ahept[0] * R * T -
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Ahept[1] -
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Ahept[2] * T2inverse +
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Ahept[3] * T3inverse -
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Ahept[4] * T4inverse;
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case 1 :
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return Ahept[5] * R * T -
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Ahept[6] -
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Ahept[7] * Tinverse;
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case 2 :
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return Ahept[9] * (Ahept[6] + Ahept[7] * Tinverse);
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case 3 :
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return Ahept[8] * T2inverse;
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default :
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return 0.0;
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}
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}
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/* cprime
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* derivative of C(i)
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*/
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inline double Heptane::Cprime(int j, double T2inverse, double T3inverse, double T4inverse)
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{
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switch (j) {
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case 0 :
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return Ahept[0] * R -
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-2 * Ahept[2] * T3inverse +
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-3 * Ahept[3] * T4inverse -
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-4 * Ahept[4] * pow(T, -5.0);
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case 1 :
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return Ahept[5] * R -
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-1 * Ahept[7] * T2inverse;
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case 2 :
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return Ahept[9] * (-1 * Ahept[7] * T2inverse);
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case 3 :
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return -2 * Ahept[8] * T3inverse;
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default :
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return 0.0;
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}
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}
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/*
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* I = integral from o-rho { 1/(rho^2) * H(i, rho) d rho }
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* ( see section 2 of Reynolds TPSI )
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*/
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inline double Heptane::I(int j, double ergho, double Gamma)
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{
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switch (j) {
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case 0:
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return Rho;
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case 1:
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return Rho * Rho / 2;
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case 2:
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return pow(Rho, 5.0)/ 5;
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case 3:
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return 1 / Gamma - (Gamma * Rho * Rho + 2) * ergho / (2 * Gamma);
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default:
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return 0.0;
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}
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}
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/* H returns a multiplier in each term of the sum
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* in P-2
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* this is used in conjunction with C in the function Pp
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* this represents the product rho^n
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* i=0 is the second additive in the formula in reynolds
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* i=1 is the third ...
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*/
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double Heptane::H(int i, double egrho)
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{
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if (i < 2) {
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return pow(Rho,i+2);
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} else if (i == 2) {
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return pow(Rho,6.0);
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} else if (i == 3) {
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return pow(Rho,3) * (1 + Gamma * Rho * Rho) * egrho;
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} else {
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return 0;
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}
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}
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/*
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* internal energy
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* see Reynolds eqn (15) section 2
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* u = (the integral from T to To of co(T)dT) +
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* sum from i to N ([C(i) - T*Cprime(i)] + uo
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*/
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double Heptane::up()
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{
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double Tinverse = 1.0/T;
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double T2inverse = pow(T, -2);
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double T3inverse = pow(T, -3);
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double T4inverse = pow(T, -4);
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double egrho = exp(-Gamma*Rho*Rho);
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double sum = 0.0;
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int i;
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for (i=1; i<=5; i++) {
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sum += G[i]*(pow(T,i) - pow(To,i))/double(i);
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}
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sum += G[0]*log(T/To);
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for (i=0; i<=6; i++) {
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sum += (C(i, Tinverse, T2inverse, T3inverse, T4inverse) - T*Cprime(i,T2inverse, T3inverse, T4inverse))*I(i,egrho, Gamma);
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}
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sum += u0;
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return sum + m_energy_offset;
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}
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/*
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* entropy
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* see Reynolds eqn (16) section 2
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*/
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double Heptane::sp()
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{
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double T2inverse = pow(T, -2);
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double T3inverse = pow(T, -3);
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double T4inverse = pow(T, -4);
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double egrho = exp(-Gamma*Rho*Rho);
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double sum = 0.0;
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for (int i=2; i<=5; i++) {
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sum += G[i]*(pow(T,i-1) - pow(To,i-1))/double(i-1);
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}
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sum += G[1]*log(T/To);
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sum -= G[0]*(1.0/T - 1.0/To);
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for (int i=0; i<=6; i++) {
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sum -= Cprime(i,T2inverse, T3inverse, T4inverse)*I(i,egrho, Gamma);
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}
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sum += s0 - R*log(Rho);
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return sum + m_entropy_offset;
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}
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/*
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* Equation P-2 in Reynolds
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* P - rho - T
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* returns P (pressure)
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*/
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double Heptane::Pp()
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{
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double Tinverse = pow(T,-1);
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double T2inverse = pow(T, -2);
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double T3inverse = pow(T, -3);
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double T4inverse = pow(T, -4);
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double egrho = exp(-Gamma*Rho*Rho);
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double P = Rho*R*T;
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for (int i=0; i<=3; i++) {
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P += C(i,Tinverse, T2inverse, T3inverse, T4inverse)*H(i,egrho);
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}
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return P;
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}
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/*
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* Equation S-2 in Reynolds
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* Pressure at Saturation
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*/
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double Heptane::Psat()
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{
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double log, sum=0,P;
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if ((T < Tmn) || (T > Tc)) {
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set_Err(TempError); // Error("Heptane::Psat",TempError,T);
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}
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for (int i=1; i<=8; i++) {
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sum += F[i-1] * pow((T/Tp -1),double(i-1));
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}
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log = ((Tc/T)-1)*sum;
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P=exp(log)*Pc;
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return P;
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}
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/*
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* Equation D2 in Reynolds
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* liquid density, of rho_f
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*/
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double Heptane::ldens()
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{
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double xx=1-(T/Tc), sum=0;
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if ((T < Tmn) || (T > Tc)) {
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set_Err(TempError);
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}
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for (int i=1; i<=6; i++) {
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sum+=D[i-1]*pow(xx,double(i-1)/3.0);
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}
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return sum;
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}
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/*
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* the following functions allow users
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* to get the properties of Heptane
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* that are not dependent on the state
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*/
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double Heptane::Tcrit()
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{
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return Tc;
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}
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double Heptane::Pcrit()
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{
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return Pc;
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}
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double Heptane::Vcrit()
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{
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return 1.0/Roc;
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}
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double Heptane::Tmin()
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{
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return Tmn;
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}
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double Heptane::Tmax()
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{
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return Tmx;
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}
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char* Heptane::name()
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{
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return (char*) m_name.c_str();
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}
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char* Heptane::formula()
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{
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return (char*) m_formula.c_str();
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}
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double Heptane::MolWt()
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{
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return M;
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}
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}
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