1 | #*------------------------------------------------------------------- |
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2 | * EMSO Model Library (EML) Copyright (C) 2004 - 2007 ALSOC. |
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3 | * |
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4 | * This LIBRARY is free software; you can distribute it and/or modify |
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5 | * it under the therms of the ALSOC FREE LICENSE as available at |
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6 | * http://www.enq.ufrgs.br/alsoc. |
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7 | * |
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8 | * EMSO Copyright (C) 2004 - 2007 ALSOC, original code |
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9 | * from http://www.rps.eng.br Copyright (C) 2002-2004. |
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10 | * All rights reserved. |
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11 | * |
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12 | * EMSO is distributed under the therms of the ALSOC LICENSE as |
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13 | * available at http://www.enq.ufrgs.br/alsoc. |
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14 | * |
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15 | *--------------------------------------------------------------------- |
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16 | * Author: Estefane Horn, Núbia do Carmo Ferreira |
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17 | *$Id: valve.mso 277 2007-06-16 20:17:45Z paula $ |
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18 | *-------------------------------------------------------------------*# |
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19 | |
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20 | using "pressure_changers/flux_machine_basic"; |
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21 | |
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22 | |
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23 | Model valve as flux_machine_basic_PH |
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24 | ATTRIBUTES |
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25 | Pallete = true; |
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26 | Icon = "Valve"; |
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27 | Brief = "Model of a valve."; |
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28 | Info = |
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29 | "Model of valves: |
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30 | * Linear; |
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31 | * Parabolic; |
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32 | * Equal; |
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33 | * Quick; |
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34 | * Hyperbolic. |
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35 | |
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36 | Assumptions: |
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37 | * Steady State; |
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38 | * Liquid; |
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39 | * Isentalpic. |
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40 | |
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41 | Specify: |
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42 | * the valve type; |
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43 | * the inlet stream; |
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44 | * the Volumetric Flow (Qv); |
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45 | * the Valve Coefficient (cv); |
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46 | * the opening (x). |
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47 | "; |
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48 | |
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49 | PARAMETERS |
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50 | valve_type as Switcher (Valid = ["linear", "parabolic", "equal", "quick", "hyperbolic"], Default = "linear"); |
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51 | outer PP as Plugin (Brief = "External Physical Properties", Type = "PP"); |
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52 | outer NComp as Integer (Brief = "Number of chemical components", Lower = 1); |
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53 | rho60F as dens_mass; |
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54 | |
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55 | VARIABLES |
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56 | Pdiff as press_delta (Brief = "Pressure Increase"); |
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57 | Qv as flow_vol (Brief = "Volumetric Flow"); |
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58 | fc as positive (Brief = "Opening Function"); |
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59 | cv as positive (Brief = "Valve Coefficient", Unit = 'm^3/h/kPa^0.5'); |
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60 | Gf as positive (Brief = "Specific Gravity"); |
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61 | rho as dens_mass; |
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62 | vm as vol_mol (Brief = "Mixture Molar Volume"); |
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63 | x as fraction (Brief = "Opening"); |
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64 | |
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65 | SET |
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66 | rho60F = 999.02 * 'kg/m^3'; |
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67 | |
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68 | EQUATIONS |
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69 | "Calculate Outlet Stream Pressure" |
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70 | Inlet.P - Outlet.P = Pdiff; |
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71 | |
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72 | "Enthalpy Balance" |
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73 | Outlet.h = Inlet.h; |
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74 | |
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75 | "Molar Balance" |
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76 | Outlet.F = Inlet.F; |
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77 | |
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78 | "Calculate Outlet Composition" |
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79 | Outlet.z = Inlet.z; |
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80 | |
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81 | if Pdiff > 0 then |
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82 | "Valve Equation - Flow" |
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83 | Qv = fc*cv*sqrt(Pdiff/Gf); |
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84 | else |
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85 | "Valve Equation - Closed" |
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86 | Qv = 0 * 'm^3/h'; |
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87 | end |
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88 | |
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89 | "Calculate Gf" |
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90 | Gf = rho/rho60F; |
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91 | |
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92 | "Calculate Specific Mass" |
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93 | rho = PP.LiquidDensity(Inlet.T,Inlet.P,Inlet.z); |
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94 | |
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95 | "Calculate Mass Flow" |
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96 | Qv = Inlet.F*vm; |
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97 | |
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98 | "Calculate Liquid Molar Volume" |
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99 | vm = PP.LiquidVolume(Inlet.T,Inlet.P,Inlet.z); |
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100 | |
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101 | switch valve_type |
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102 | case "linear": |
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103 | |
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104 | "Opening Equation" |
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105 | fc = x; |
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106 | |
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107 | case "parabolic": |
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108 | |
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109 | "Opening Equation" |
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110 | fc = x^2; |
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111 | |
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112 | case "equal": |
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113 | |
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114 | "Opening Equation" |
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115 | fc = x^2/(2-x^4)^(1/2); |
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116 | |
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117 | case "quick": |
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118 | |
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119 | "Opening Equation" |
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120 | fc = 10*x/sqrt(1+99*x^2); |
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121 | |
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122 | case "hyperbolic": |
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123 | |
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124 | "Opening Equation" |
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125 | fc = 0.1*x/sqrt(1-0.99*x^2); |
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126 | |
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127 | end |
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128 | end |
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129 | |
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130 | #*------------------------------------------------------------------- |
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131 | * Model of a valve (simplified) |
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132 | *-------------------------------------------------------------------- |
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133 | * |
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134 | * Author: Paula B. Staudt |
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135 | *--------------------------------------------------------------------*# |
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136 | Model valve_simplified |
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137 | ATTRIBUTES |
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138 | Pallete = true; |
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139 | Icon = "Valve"; |
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140 | Brief = "Model of a very simple valve - used in distillation column models."; |
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141 | Info = |
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142 | "Assumptions: |
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143 | * no flashing liquid in the valve; |
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144 | * the flow in the valve is adiabatic; |
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145 | * dynamics in the valve are neglected; |
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146 | * linear flow type. |
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147 | |
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148 | Specify: |
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149 | * the inlet stream |
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150 | * the plug position (x) OR outlet temperature (Outlet.T) OR outlet pressure (Outlet.P) |
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151 | |
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152 | OR |
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153 | |
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154 | * the inlet stream excluding its flow (Inlet.F) |
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155 | * the outlet pressure (Outlet.P) OR outlet flow (Outlet.F) |
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156 | * the plug position (x) |
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157 | "; |
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158 | |
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159 | PARAMETERS |
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160 | outer PP as Plugin(Type="PP"); |
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161 | outer NComp as Integer; |
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162 | |
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163 | VARIABLES |
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164 | in Inlet as stream; |
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165 | out Outlet as streamPH; |
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166 | x as fraction (Brief="Plug Position"); |
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167 | rho as dens_mass (Brief="Fluid Density", Default=1e3); |
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168 | v as vol_mol (Brief="Specific volume", Default=1e3); |
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169 | |
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170 | PARAMETERS |
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171 | rho_ref as dens_mass (Brief="Reference Density", Default=1e4); |
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172 | k as Real (Brief="Valve Constant", Unit='gal/min/psi^0.5'); |
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173 | |
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174 | EQUATIONS |
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175 | "Molar Balance" |
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176 | Inlet.F = Outlet.F; |
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177 | Inlet.z = Outlet.z; |
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178 | |
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179 | "Energy Balance" |
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180 | Inlet.h = Outlet.h; |
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181 | |
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182 | "Density" |
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183 | rho = Inlet.v*PP.VapourDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) + |
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184 | (1-Inlet.v)*PP.LiquidDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z); |
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185 | |
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186 | "Volume" |
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187 | v = Inlet.v*PP.VapourVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) + |
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188 | (1-Inlet.v)*PP.LiquidVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z); |
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189 | |
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190 | if Inlet.P > Outlet.P then |
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191 | "Flow" |
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192 | Outlet.F * v = k*x*sqrt((Inlet.P - Outlet.P)*rho_ref / rho ) ; |
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193 | else |
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194 | "Closed" |
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195 | Outlet.F = 0 * 'kmol/h'; |
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196 | end |
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197 | end |
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