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 | * Model of valves: |
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17 | * |
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18 | * - Linear |
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19 | * - Parabolic |
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20 | * - Equal |
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21 | * - Quick |
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22 | * - valve: a very simple model |
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23 | * |
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24 | *-------------------------------------------------------------------- |
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25 | * - Assumptions |
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26 | * * Steady State |
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27 | * * Isentalpic |
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28 | * * Liquid |
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29 | * |
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30 | *--------------------------------------------------------------------- |
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31 | * Author: Estefane Horn, Núbia do Carmo Ferreira |
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32 | *$Id: valve.mso 98 2007-01-06 12:49:32Z nubinha $ |
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33 | *-------------------------------------------------------------------*# |
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34 | |
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35 | using "streams"; |
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36 | using "pressure_changers/flux_machine_basic"; |
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37 | |
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38 | |
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39 | Model valve_basic as flux_machine_basic_TP |
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40 | |
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41 | PARAMETERS |
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42 | ext PP as CalcObject (Brief = "External Physical Properties", File = "vrpp"); |
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43 | ext NComp as Integer (Brief = "Number of chemical components", Lower = 1); |
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44 | rho60F as dens_mass; |
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45 | |
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46 | VARIABLES |
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47 | Pdiff as press_delta (Brief = "Pressure Increase", Unit = "kPa"); |
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48 | Qv as flow_vol (Brief = "Volumetric Flow"); |
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49 | fc as positive (Brief = "Opening Function"); |
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50 | cv as positive (Brief = "Valve Coefficient", Unit = "m^3/h/kPa^0.5"); |
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51 | Gf as positive (Brief = "Specific Gravity"); |
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52 | rho as dens_mass; |
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53 | vm as vol_mol (Brief = "Mixture Molar Volume", Unit = "m^3/kmol"); |
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54 | |
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55 | SET |
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56 | rho60F = 99.022 * "kg/m^3"; |
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57 | |
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58 | EQUATIONS |
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59 | "Calculate Outlet Stream Pressure" |
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60 | Inlet.P - Outlet.P = Pdiff; |
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61 | |
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62 | "Enthalpy Balance" |
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63 | Outlet.h = Inlet.h; |
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64 | |
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65 | "Molar Balance" |
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66 | Outlet.F = Inlet.F; |
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67 | |
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68 | "Calculate Outlet Composition" |
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69 | Outlet.z = Inlet.z; |
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70 | |
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71 | "Valve Equation" |
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72 | #if Pdiff >= 0 then |
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73 | # "Flow" |
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74 | Qv = fc*cv*sqrt(Pdiff/Gf); |
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75 | #else |
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76 | # "Closed" |
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77 | # Pdiff < 0 * "kmol/h"; |
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78 | #end |
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79 | |
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80 | "Calculate Gf" |
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81 | Gf = rho/rho60F; |
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82 | |
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83 | "Calculate Specific Mass" |
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84 | rho = PP.LiquidDensity(Inlet.T,Inlet.P,Inlet.z); |
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85 | |
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86 | "Calculate Mass Flow" |
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87 | Qv = Inlet.F*vm; |
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88 | |
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89 | "Calculate Liquid Molar Volume" |
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90 | vm = PP.LiquidVolume(Inlet.T,Inlet.P,Inlet.z); |
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91 | |
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92 | end |
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93 | |
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94 | Model valve_linear as valve_basic |
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95 | |
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96 | VARIABLES |
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97 | x as fraction (Brief = "Opening"); |
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98 | |
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99 | EQUATIONS |
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100 | |
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101 | "Opening Equation" |
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102 | fc = 1*x; |
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103 | |
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104 | end |
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105 | |
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106 | Model valve_parabolic as valve_basic |
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107 | |
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108 | PARAMETERS |
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109 | n as positive (Brief = "Constant", Lower = 1.4, Upper = 2.6); |
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110 | |
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111 | VARIABLES |
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112 | x as fraction (Brief = "Opening"); |
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113 | |
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114 | EQUATIONS |
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115 | |
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116 | "Opening Equation" |
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117 | fc = 1*x^n; |
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118 | |
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119 | end |
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120 | |
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121 | Model valve_equal as valve_basic |
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122 | |
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123 | PARAMETERS |
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124 | a as Real (Brief = "Constant", Default = 100); |
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125 | |
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126 | VARIABLES |
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127 | x as fraction (Brief = "Opening"); |
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128 | |
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129 | EQUATIONS |
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130 | |
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131 | "Opening Equation" |
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132 | fc = a^(x-1); |
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133 | |
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134 | end |
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135 | |
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136 | Model valve_quick as valve_basic |
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137 | |
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138 | PARAMETERS |
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139 | a as positive (Brief = "Constant", Default = 0.05); |
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140 | n as positive (Brief = "Constant", Default = 5); |
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141 | |
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142 | VARIABLES |
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143 | x as fraction (Brief = "Opening"); |
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144 | |
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145 | EQUATIONS |
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146 | |
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147 | "Opening Equation" |
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148 | fc = (1-(a*(1-x)-(a-1)*(1-x)^n)); |
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149 | |
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150 | end |
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151 | |
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152 | #*------------------------------------------------------------------- |
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153 | * Model of a valve (simplified) |
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154 | *-------------------------------------------------------------------- |
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155 | * |
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156 | * Streams: |
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157 | * * an inlet stream |
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158 | * * an outlet stream |
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159 | * |
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160 | * Assumptions: |
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161 | * * no flashing liquid in the valve |
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162 | * * the flow in the valve is adiabatic |
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163 | * * dynamics in the valve are neglected |
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164 | * * linear flow type |
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165 | * |
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166 | * Specify: |
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167 | * * the inlet stream |
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168 | * * one of: plug position (x), outlet temperature (Outlet.T) or |
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169 | * outlet pressure (Outlet.P) |
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170 | * or |
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171 | * * the inlet stream excluding its flow (Inlet.F) |
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172 | * * the outlet pressure (Outlet.P) OR outlet flow (Outlet.F) |
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173 | * * the plug position (x) |
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174 | * |
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175 | * |
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176 | *---------------------------------------------------------------------- |
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177 | * Author: Paula B. Staudt |
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178 | *--------------------------------------------------------------------*# |
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179 | Model valve |
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180 | PARAMETERS |
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181 | ext PP as CalcObject; |
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182 | ext NComp as Integer; |
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183 | |
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184 | VARIABLES |
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185 | in Inlet as stream; |
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186 | out Outlet as stream_therm; |
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187 | x as fraction (Brief="Plug Position"); |
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188 | rho as dens_mass (Brief="Fluid Density", Default=1e3); |
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189 | v as vol_mol (Brief="Specific volume", Default=1e3); |
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190 | |
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191 | PARAMETERS |
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192 | rho_ref as dens_mass (Brief="Reference Density", Default=1e4); |
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193 | k as Real (Brief="Valve Constant", Unit="gal/min/psi^0.5"); |
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194 | |
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195 | EQUATIONS |
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196 | "Molar Balance" |
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197 | Inlet.F = Outlet.F; |
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198 | Inlet.z = Outlet.z; |
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199 | |
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200 | "Energy Balance" |
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201 | Inlet.h = Outlet.h; |
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202 | |
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203 | "Vapourisation Fraction" |
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204 | Outlet.v = Inlet.v; |
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205 | |
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206 | "Density" |
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207 | rho = Inlet.v*PP.VapourDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) + |
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208 | (1-Inlet.v)*PP.LiquidDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z); |
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209 | |
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210 | "Volume" |
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211 | v = Inlet.v*PP.VapourVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) + |
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212 | (1-Inlet.v)*PP.LiquidVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z); |
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213 | |
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214 | #if Inlet.P > Outlet.P then |
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215 | # "Flow" |
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216 | Outlet.F * v = cv*x*sqrt((Inlet.P - Outlet.P)*rho_ref / rho ) ; |
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217 | #else |
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218 | # "Closed" |
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219 | # Outlet.F = 0 * "kmol/h"; |
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220 | #end |
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221 | end |
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