source: trunk/eml/pressure_changers/valve.mso @ 837

Last change on this file since 837 was 372, checked in by Argimiro Resende Secchi, 16 years ago

Adding pressure drop variable (Pdrop) and pressure ratio (Pratio) in some models. Need to do the same for other models.
  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 5.3 KB
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1#*-------------------------------------------------------------------
2* EMSO Model Library (EML) Copyright (C) 2004 - 2007 ALSOC.
3*
4* This LIBRARY is free software; you can distribute it and/or modify
5* it under the therms of the ALSOC FREE LICENSE as available at
6* http://www.enq.ufrgs.br/alsoc.
7*
8* EMSO Copyright (C) 2004 - 2007 ALSOC, original code
9* from http://www.rps.eng.br Copyright (C) 2002-2004.
10* All rights reserved.
11*
12* EMSO is distributed under the therms of the ALSOC LICENSE as
13* available at http://www.enq.ufrgs.br/alsoc.
14*
15*---------------------------------------------------------------------
16* Author: Estefane Horn, Núbia do Carmo Ferreira
17*$Id: valve.mso 372 2007-09-21 22:17:36Z arge $                                                                 
18*-------------------------------------------------------------------*#
19
20using "streams";
21       
22
23Model valve
24        ATTRIBUTES
25        Pallete         = true;
26        Icon            = "icon/Valve";
27        Brief           = "Model of a valve.";
28        Info            =
29"== Model of valves ==
30* Linear;
31* Parabolic;
32* Equal;
33* Quick;
34* Hyperbolic.
35       
36== Assumptions ==
37* Steady State;
38* Liquid;
39* Isentalpic.
40       
41== Specify ==
42* the valve type;
43* the inlet stream;
44* the Volumetric Flow (Qv);
45* the Valve Coefficient (cv);
46* the opening (x).
47";
48               
49        PARAMETERS
50        valve_type as Switcher (Valid = ["linear", "parabolic", "equal", "quick", "hyperbolic"], Default = "linear");
51outer PP                as Plugin       (Brief = "External Physical Properties", Type = "PP");
52outer NComp     as Integer      (Brief = "Number of chemical components", Lower = 1);
53        rho60F  as dens_mass;
54
55        VARIABLES
56        Pratio  as positive                     (Brief = "Pressure Ratio", Symbol ="P_{ratio}");       
57        Pdrop   as press_delta          (Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P");
58        Qv              as flow_vol                     (Brief = "Volumetric Flow");
59        fc              as positive                     (Brief = "Opening Function");
60        cv              as positive                     (Brief = "Valve Coefficient", Unit = 'm^3/h/kPa^0.5');
61        Gf              as positive                     (Brief = "Specific Gravity");
62        rho     as dens_mass;   
63        vm              as vol_mol                      (Brief = "Mixture Molar Volume");       
64        x               as fraction             (Brief = "Opening");
65in      Inlet   as stream                       (Brief = "Inlet stream", PosX=0, PosY=0.7365, Symbol="_{in}");
66out     Outlet  as streamPH                     (Brief = "Outlet stream", PosX=1, PosY=0.7365, Symbol="_{out}");
67       
68        SET
69        rho60F = 999.02 * 'kg/m^3';
70       
71        EQUATIONS
72        "Pressure Drop"
73        Outlet.P  = Inlet.P - Pdrop;
74
75        "Pressure Ratio"
76        Outlet.P = Inlet.P * Pratio;
77       
78        "Enthalpy Balance"
79        Outlet.h = Inlet.h;
80       
81        "Molar Balance"
82        Outlet.F = Inlet.F;
83       
84        "Calculate Outlet Composition"
85        Outlet.z = Inlet.z;
86
87        if Pdrop > 0 then
88                "Valve Equation - Flow"
89                Qv = fc*cv*sqrt(Pdrop/Gf);     
90        else
91                "Valve Equation - Closed"
92                Qv = 0 * 'm^3/h';
93        end
94       
95        "Calculate Gf"
96        Gf = rho/rho60F;
97       
98        "Calculate Specific Mass"
99        rho = PP.LiquidDensity(Inlet.T,Inlet.P,Inlet.z);
100       
101        "Calculate Mass Flow"
102        Qv = Inlet.F*vm;       
103       
104        "Calculate Liquid Molar Volume"
105        vm = PP.LiquidVolume(Inlet.T,Inlet.P,Inlet.z);
106       
107        switch valve_type
108        case "linear":
109
110                "Opening Equation"
111                fc = x;
112
113        case "parabolic":
114
115                "Opening Equation"
116                fc = x^2;
117
118        case "equal":
119
120                "Opening Equation"
121                fc = x^2/(2-x^4)^(1/2);
122
123        case "quick":
124       
125                "Opening Equation"
126                fc = 10*x/sqrt(1+99*x^2);
127
128        case "hyperbolic":
129
130                "Opening Equation"
131                fc = 0.1*x/sqrt(1-0.99*x^2);
132
133        end
134end
135
136#*-------------------------------------------------------------------
137* Model of a valve (simplified)
138*--------------------------------------------------------------------
139*
140* Author: Paula B. Staudt
141*--------------------------------------------------------------------*#
142Model valve_simplified
143        ATTRIBUTES
144        Pallete         = true;
145        Icon            = "icon/Valve";
146        Brief           = "Model of a very simple valve - used in distillation column models.";
147        Info            =
148"== Assumptions ==
149* no flashing liquid in the valve;
150* the flow in the valve is adiabatic;
151* dynamics in the valve are neglected;
152* linear flow type.
153       
154== Specify ==
155* the inlet stream
156* the plug position (x) OR outlet temperature (Outlet.T) OR outlet pressure (Outlet.P)
157       
158        OR             
159       
160* the inlet stream excluding its flow (Inlet.F)
161* the outlet pressure (Outlet.P) OR outlet flow (Outlet.F)
162* the plug position (x)
163";
164
165        PARAMETERS
166outer PP as Plugin(Type="PP");
167outer NComp as Integer;
168       
169        VARIABLES
170in      Inlet   as stream       (Brief = "Inlet stream", PosX=0, PosY=0.7365, Symbol="_{in}");
171out     Outlet  as streamPH     (Brief = "Outlet stream", PosX=1, PosY=0.7365, Symbol="_{out}");
172        x as fraction (Brief="Plug Position");
173        rho as dens_mass (Brief="Fluid Density", Default=1e3);
174        v as vol_mol (Brief="Specific volume", Default=1e3);
175        Pdrop     as press_delta (Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P");
176        Pratio  as positive     (Brief = "Pressure Ratio", Symbol ="P_{ratio}");       
177
178        PARAMETERS
179        rho_ref as dens_mass (Brief="Reference Density", Default=1e4);
180        k as Real (Brief="Valve Constant", Unit='gal/min/psi^0.5');
181
182        EQUATIONS
183        "Overall Molar Balance"
184        Inlet.F = Outlet.F;
185       
186        "Componente Molar Balance"
187        Inlet.z = Outlet.z;
188       
189        "Energy Balance"
190        Inlet.h = Outlet.h;
191
192        "Pressure Drop"
193        Outlet.P  = Inlet.P - Pdrop;
194
195        "Pressure Ratio"
196        Outlet.P = Inlet.P * Pratio;
197
198        "Density"
199        rho = Inlet.v*PP.VapourDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) +
200                (1-Inlet.v)*PP.LiquidDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z);
201
202        "Volume"
203        v = Inlet.v*PP.VapourVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) +
204                (1-Inlet.v)*PP.LiquidVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z);
205
206        if Pdrop > 0 then
207                "Flow"
208                Outlet.F * v = k*x*sqrt(Pdrop * rho_ref / rho ) ;
209        else
210                "Closed"
211                Outlet.F = 0 * 'kmol/h';
212        end
213end
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