/[ascend]/trunk/models/johnpye/fprops/ideal.h
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revision 1848 by jpye, Mon Sep 1 05:42:21 2008 UTC revision 1849 by jpye, Mon Sep 1 14:48:55 2008 UTC
# Line 1  Line 1 
1    /*  ASCEND modelling environment
2        Copyright (C) 2008 Carnegie Mellon University
3    
4        This program is free software; you can redistribute it and/or modify
5        it under the terms of the GNU General Public License as published by
6        the Free Software Foundation; either version 2, or (at your option)
7        any later version.
8    
9        This program is distributed in the hope that it will be useful,
10        but WITHOUT ANY WARRANTY; without even the implied warranty of
11        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12        GNU General Public License for more details.
13    
14        You should have received a copy of the GNU General Public License
15        along with this program; if not, write to the Free Software
16        Foundation, Inc., 59 Temple Place - Suite 330,
17        Boston, MA 02111-1307, USA.
18    */
19  #ifndef FPROPS_IDEAL_H  #ifndef FPROPS_IDEAL_H
20  #define FPROPS_IDEAL_H  #define FPROPS_IDEAL_H
21    
# Line 20  typedef struct IdealPowTerm_struct{ Line 38  typedef struct IdealPowTerm_struct{
38  } IdealPowTerm;  } IdealPowTerm;
39    
40  /*  /*
41        Terms containing exponential expressions with tau, like
42    
43        b x^2 exp(-x) / [1-exp(-x)]^2
44    
45        where x = beta / T. Instead of representing in terms of beta, we ask the
46        user to provide (b,beta) in the form of
47    
48            b,B
49    
50        where B = beta / T*, with T* being the normalisation temperature used
51        to calculate tau in the main 'residual' correlation.
52    
53      See J R Cooper 'Representation of the Ideal-Gas Thermaldynamic      See J R Cooper 'Representation of the Ideal-Gas Thermaldynamic
54      Properties of Water', Int J Thermophys v 3 no 1, 1982 and also      Properties of Water', Int J Thermophys v 3 no 1, 1982 and also
55      Span, Lemmon, Jacobsen & Wagner 'A Reference Quality Equation of State      Span, Lemmon, Jacobsen & Wagner 'A Reference Quality Equation of State
56      for Nitrogen' 1998.      for Nitrogen' 1998.
57    
58      The form of exponential terms appearing in the reduced      From the above expression, the term appearing in the reduced
59      Helmholtz function equation is      Helmholtz function equation becomes
60    
61            b_i ln [ 1 - exp( -B_i tau ) ]
62    
63        This is the component in tau, there is also a constant term added,
64    
65          b ln [ 1 - exp( -B tau ) ]          - b_i ln [ 1 - exp( -B_i tau0 ) ]
66    
     where B is defined as beta / tau in the nomenclature of Cooper.  
67  */  */
68  typedef struct IdealExpTerm_struct{  typedef struct IdealExpTerm_struct{
69      double b;      double b;
# Line 38  typedef struct IdealExpTerm_struct{ Line 71  typedef struct IdealExpTerm_struct{
71  } IdealExpTerm;  } IdealExpTerm;
72    
73  typedef struct  IdealData_struct{  typedef struct  IdealData_struct{
74      double c; /* constant value in phi_0 expression */      double c;
75      double m; /* linear coefficient in phi_0 expression */      double m;
76      unsigned np; /* number of power terms */      unsigned np; /* number of power terms */
77      const IdealPowTerm *pt; /* power term data, may be NULL if np == 0 */      const IdealPowTerm *pt; /* power term data, may be NULL if np == 0 */
78      unsigned ne; /* number of 'exponential' terms */      unsigned ne; /* number of 'exponential' terms */
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john.pye@anu.edu.au
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