/[ascend]/trunk/models/johnpye/fprops/ideal.h
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Contents of /trunk/models/johnpye/fprops/ideal.h

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Revision 1849 - (show annotations) (download) (as text)
Mon Sep 1 14:48:55 2008 UTC (14 years, 9 months ago) by jpye
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Working on fixing the ideal component curves so that they calculate
directly from the cp0(T) form. Currently broken.
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
20 #define FPROPS_IDEAL_H
21
22 /*
23 Data types for declaration of ideal fluid components of property
24 correlations. Frequently property correlations for 'real' fluids are
25 given in terms of ideal gas components plus 'residual' or 'real'
26 components. For these cases, this file defines the data structures
27 used to declare those ideal component curves.
28 */
29
30 /*
31 Terms containing powers of 'tau', like
32
33 a0 * tau^t0
34 */
35 typedef struct IdealPowTerm_struct{
36 double a0;
37 double t0;
38 } 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
54 Properties of Water', Int J Thermophys v 3 no 1, 1982 and also
55 Span, Lemmon, Jacobsen & Wagner 'A Reference Quality Equation of State
56 for Nitrogen' 1998.
57
58 From the above expression, the term appearing in the reduced
59 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_i ln [ 1 - exp( -B_i tau0 ) ]
66
67 */
68 typedef struct IdealExpTerm_struct{
69 double b;
70 double B;
71 } IdealExpTerm;
72
73 typedef struct IdealData_struct{
74 double c;
75 double m;
76 unsigned np; /* number of power terms */
77 const IdealPowTerm *pt; /* power term data, may be NULL if np == 0 */
78 unsigned ne; /* number of 'exponential' terms */
79 const IdealExpTerm *et; /* exponential term data, maybe NULL if ne == 0 */
80 } IdealData;
81
82 #endif
83

john.pye@anu.edu.au
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