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: Gerson Balbueno Bicca |
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17 | * $Id: HeatExchangerSimplified.mso 160 2007-02-08 18:37:44Z bicca $ |
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18 | *--------------------------------------------------------------------*# |
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19 | |
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20 | using "heat_exchangers/HEX_Engine"; |
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21 | |
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22 | Model HeatExchangerSimplified_Basic |
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23 | |
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24 | ATTRIBUTES |
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25 | Pallete = false; |
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26 | Brief = "Basic Models for Simplified Heat Exchangers"; |
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27 | Info = |
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28 | "to be documented."; |
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29 | |
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30 | PARAMETERS |
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31 | outer PP as Plugin (Brief="External Physical Properties", Type="PP"); |
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32 | outer NComp as Integer (Brief="Number of Components"); |
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33 | |
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34 | M(NComp) as molweight (Brief="Component Mol Weight"); |
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35 | |
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36 | VARIABLES |
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37 | |
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38 | in InletHot as stream (Brief="Inlet Hot Stream", PosX=0, PosY=0.4915, Symbol="^{inHot}"); |
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39 | out OutletHot as streamPH (Brief="Outlet Hot Stream", PosX=1, PosY=0.4915, Symbol="^{outHot}"); |
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40 | in InletCold as stream (Brief="Inlet Cold Stream", PosX=0.5237, PosY=1, Symbol="^{inCold}"); |
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41 | out OutletCold as streamPH (Brief="Outlet Cold Stream", PosX=0.5237, PosY=0, Symbol="^{outCold}"); |
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42 | |
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43 | xh(NComp) as fraction (Brief = "Liquid Molar Fraction in Hot Side"); |
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44 | yh(NComp) as fraction (Brief = "Vapour Molar Fraction in Hot Side"); |
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45 | vh as fraction (Brief = "Vapour Molar Fraction in Hot Side"); |
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46 | |
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47 | xc(NComp) as fraction (Brief = "Liquid Molar Fraction in Cold Side"); |
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48 | yc(NComp) as fraction (Brief = "Vapour Molar Fraction in Cold Side"); |
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49 | vc as fraction (Brief = "Vapour Molar Fraction in Cold Side"); |
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50 | |
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51 | Details as Details_Main (Brief="Heat Exchanger Details", Symbol=" "); |
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52 | HotSide as Main_Simplified (Brief="Heat Exchanger Hot Side", Symbol="_{hot}"); |
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53 | ColdSide as Main_Simplified (Brief="Heat Exchanger Cold Side", Symbol="_{cold}"); |
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54 | |
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55 | SET |
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56 | |
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57 | #"Component Molecular Weight" |
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58 | M = PP.MolecularWeight(); |
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59 | |
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60 | EQUATIONS |
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61 | |
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62 | "Flash Calculation in Hot Side" |
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63 | [vh, xh, yh] = PP.Flash(InletHot.T, InletHot.P, InletHot.z); |
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64 | |
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65 | "Flash Calculation in Cold Side" |
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66 | [vc, xc, yc] = PP.Flash(InletCold.T, InletCold.P, InletCold.z); |
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67 | |
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68 | "Hot Stream Average Temperature" |
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69 | HotSide.Properties.Average.T = 0.5*InletHot.T + 0.5*OutletHot.T; |
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70 | |
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71 | "Cold Stream Average Temperature" |
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72 | ColdSide.Properties.Average.T = 0.5*InletCold.T + 0.5*OutletCold.T; |
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73 | |
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74 | "Hot Stream Average Pressure" |
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75 | HotSide.Properties.Average.P = 0.5*InletHot.P+0.5*OutletHot.P; |
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76 | |
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77 | "Cold Stream Average Pressure" |
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78 | ColdSide.Properties.Average.P = 0.5*InletCold.P+0.5*OutletCold.P; |
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79 | |
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80 | "Cold Stream Wall Temperature" |
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81 | ColdSide.Properties.Wall.Twall = 0.5*HotSide.Properties.Average.T + 0.5*ColdSide.Properties.Average.T; |
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82 | |
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83 | "Hot Stream Wall Temperature" |
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84 | HotSide.Properties.Wall.Twall = 0.5*HotSide.Properties.Average.T + 0.5*ColdSide.Properties.Average.T; |
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85 | |
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86 | "Hot Stream Average Molecular Weight" |
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87 | HotSide.Properties.Average.Mw = sum(M*InletHot.z); |
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88 | |
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89 | "Cold Stream Average Molecular Weight" |
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90 | ColdSide.Properties.Average.Mw = sum(M*InletCold.z); |
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91 | |
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92 | "Cold Stream Average Heat Capacity" |
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93 | ColdSide.Properties.Average.Cp = (1-InletCold.v)*PP.LiquidCp(ColdSide.Properties.Average.T,ColdSide.Properties.Average.P,xc) + |
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94 | InletCold.v*PP.VapourCp(ColdSide.Properties.Average.T,ColdSide.Properties.Average.P,yc); |
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95 | |
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96 | "Cold Stream Average Mass Density" |
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97 | ColdSide.Properties.Average.rho = (1-InletCold.v)*PP.LiquidDensity(ColdSide.Properties.Average.T,ColdSide.Properties.Average.P,xc)+ |
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98 | InletCold.v*PP.VapourDensity(ColdSide.Properties.Average.T,ColdSide.Properties.Average.P,yc); |
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99 | |
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100 | "Cold Stream Inlet Mass Density" |
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101 | ColdSide.Properties.Inlet.rho = (1-InletCold.v)*PP.LiquidDensity(InletCold.T,InletCold.P,xc)+ |
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102 | InletCold.v*PP.VapourDensity(InletCold.T,InletCold.P,yc); |
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103 | |
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104 | "Cold Stream Outlet Mass Density" |
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105 | ColdSide.Properties.Outlet.rho = (1-OutletCold.v)*PP.LiquidDensity(OutletCold.T,OutletCold.P,OutletCold.x)+ |
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106 | OutletCold.v*PP.VapourDensity(OutletCold.T,OutletCold.P,OutletCold.y); |
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107 | |
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108 | "Cold Stream Average Viscosity" |
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109 | ColdSide.Properties.Average.Mu = (1-InletCold.v)*PP.LiquidViscosity(ColdSide.Properties.Average.T,ColdSide.Properties.Average.P,xc)+ |
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110 | InletCold.v*PP.VapourViscosity(ColdSide.Properties.Average.T,ColdSide.Properties.Average.P,yc); |
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111 | |
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112 | "Cold Stream Average Conductivity" |
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113 | ColdSide.Properties.Average.K = (1-InletCold.v)*PP.LiquidThermalConductivity(ColdSide.Properties.Average.T,ColdSide.Properties.Average.P,xc)+ |
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114 | InletCold.v*PP.VapourThermalConductivity(ColdSide.Properties.Average.T,ColdSide.Properties.Average.P,yc); |
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115 | |
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116 | "Cold Stream Viscosity at Wall Temperature" |
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117 | ColdSide.Properties.Wall.Mu = (1-InletCold.v)*PP.LiquidViscosity(ColdSide.Properties.Wall.Twall,ColdSide.Properties.Average.P,xc)+ |
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118 | InletCold.v*PP.VapourViscosity(ColdSide.Properties.Wall.Twall,ColdSide.Properties.Average.P,yc); |
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119 | |
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120 | "Hot Stream Average Heat Capacity" |
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121 | HotSide.Properties.Average.Cp = (1-InletHot.v)*PP.LiquidCp(HotSide.Properties.Average.T,HotSide.Properties.Average.P,xc) + |
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122 | InletHot.v*PP.VapourCp(HotSide.Properties.Average.T,HotSide.Properties.Average.P,yc); |
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123 | |
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124 | "Hot Stream Average Mass Density" |
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125 | HotSide.Properties.Average.rho = (1-InletHot.v)*PP.LiquidDensity(HotSide.Properties.Average.T,HotSide.Properties.Average.P,xc)+ |
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126 | InletHot.v*PP.VapourDensity(HotSide.Properties.Average.T,HotSide.Properties.Average.P,yc); |
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127 | |
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128 | "Hot Stream Inlet Mass Density" |
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129 | HotSide.Properties.Inlet.rho = (1-InletHot.v)*PP.LiquidDensity(InletHot.T,InletHot.P,xc)+ |
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130 | InletHot.v*PP.VapourDensity(InletHot.T,InletHot.P,yc); |
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131 | |
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132 | "Hot Stream Outlet Mass Density" |
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133 | HotSide.Properties.Outlet.rho = (1-OutletHot.v)*PP.LiquidDensity(OutletHot.T,OutletHot.P,OutletHot.x)+ |
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134 | OutletHot.v*PP.VapourDensity(OutletHot.T,OutletHot.P,OutletHot.y); |
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135 | |
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136 | "Hot Stream Average Viscosity" |
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137 | HotSide.Properties.Average.Mu = (1-InletHot.v)*PP.LiquidViscosity(HotSide.Properties.Average.T,HotSide.Properties.Average.P,xc)+ |
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138 | InletHot.v*PP.VapourViscosity(HotSide.Properties.Average.T,HotSide.Properties.Average.P,yc); |
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139 | |
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140 | "Hot Stream Average Conductivity" |
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141 | HotSide.Properties.Average.K = (1-InletHot.v)*PP.LiquidThermalConductivity(HotSide.Properties.Average.T,HotSide.Properties.Average.P,xc)+ |
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142 | InletHot.v*PP.VapourThermalConductivity(HotSide.Properties.Average.T,HotSide.Properties.Average.P,yc); |
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143 | |
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144 | "Hot Stream Viscosity at Wall Temperature" |
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145 | HotSide.Properties.Wall.Mu = (1-InletHot.v)*PP.LiquidViscosity(HotSide.Properties.Wall.Twall,HotSide.Properties.Average.P,xc)+ |
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146 | InletHot.v*PP.VapourViscosity(HotSide.Properties.Wall.Twall,HotSide.Properties.Average.P,yc); |
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147 | |
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148 | "Energy Balance Hot Stream" |
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149 | Details.Q = InletHot.F*(InletHot.h-OutletHot.h); |
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150 | |
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151 | "Energy Balance Cold Stream" |
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152 | Details.Q =-InletCold.F*(InletCold.h-OutletCold.h); |
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153 | |
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154 | "Flow Mass Inlet Cold Stream" |
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155 | ColdSide.Properties.Inlet.Fw = sum(M*InletCold.z)*InletCold.F; |
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156 | |
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157 | "Flow Mass Outlet Cold Stream" |
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158 | ColdSide.Properties.Outlet.Fw = sum(M*OutletCold.z)*OutletCold.F; |
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159 | |
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160 | "Flow Mass Inlet Hot Stream" |
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161 | HotSide.Properties.Inlet.Fw = sum(M*InletHot.z)*InletHot.F; |
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162 | |
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163 | "Flow Mass Outlet Hot Stream" |
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164 | HotSide.Properties.Outlet.Fw = sum(M*OutletHot.z)*OutletHot.F; |
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165 | |
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166 | "Molar Balance Hot Stream" |
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167 | InletHot.F = OutletHot.F; |
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168 | |
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169 | "Molar Balance Cold Stream" |
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170 | InletCold.F = OutletCold.F; |
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171 | |
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172 | "Hot Stream Molar Fraction Constraint" |
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173 | OutletHot.z = InletHot.z; |
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174 | |
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175 | "Cold Stream Molar Fraction Constraint" |
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176 | OutletCold.z = InletCold.z; |
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177 | |
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178 | "Pressure Drop Hot Stream" |
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179 | OutletHot.P = InletHot.P - HotSide.PressureDrop.Pdrop; |
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180 | |
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181 | "Pressure Drop Cold Stream" |
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182 | OutletCold.P = InletCold.P - ColdSide.PressureDrop.Pdrop; |
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183 | |
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184 | "Fraction of Inlet Pressure : Hot Stream" |
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185 | HotSide.PressureDrop.Pdrop = InletHot.P*HotSide.PressureDrop.FPdrop; |
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186 | |
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187 | "Fraction of Inlet Pressure : Cold Stream" |
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188 | ColdSide.PressureDrop.Pdrop = InletCold.P*ColdSide.PressureDrop.FPdrop; |
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189 | |
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190 | end |
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191 | |
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192 | Model HeatExchanger_LMTD as HeatExchangerSimplified_Basic |
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193 | |
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194 | ATTRIBUTES |
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195 | Pallete = true; |
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196 | Icon = "icon/HeatExchanger_LMTD"; |
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197 | Brief = "Heat Exchanger Block - LMTD Method"; |
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198 | Info = |
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199 | "to be documented."; |
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200 | |
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201 | PARAMETERS |
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202 | |
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203 | FlowDirection as Switcher (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent"); |
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204 | |
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205 | VARIABLES |
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206 | |
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207 | Method as LMTD_Basic (Brief="LMTD Method of Calculation", Symbol =" "); |
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208 | |
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209 | EQUATIONS |
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210 | |
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211 | "Exchange Surface Area" |
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212 | Details.Q = Details.Ud*Details.A*Method.LMTD*Method.Fc; |
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213 | |
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214 | switch FlowDirection |
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215 | |
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216 | case "cocurrent": |
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217 | |
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218 | "Temperature Difference at Inlet" |
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219 | Method.DT0 = InletHot.T - InletCold.T; |
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220 | |
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221 | "Temperature Difference at Outlet" |
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222 | Method.DTL = OutletHot.T - OutletCold.T; |
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223 | |
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224 | case "counter": |
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225 | |
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226 | "Temperature Difference at Inlet" |
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227 | Method.DT0 = InletHot.T - OutletCold.T; |
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228 | |
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229 | "Temperature Difference at Outlet" |
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230 | Method.DTL = OutletHot.T - InletCold.T; |
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231 | |
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232 | end |
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233 | |
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234 | end |
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235 | |
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236 | Model Shell_and_Tubes_LMTD as HeatExchangerSimplified_Basic |
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237 | |
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238 | ATTRIBUTES |
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239 | Pallete = true; |
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240 | Icon = "icon/Shell_and_Tubes_LMTD"; |
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241 | Brief = "Shell and Tubes Heat Exchanger with 1 or 2 shell pass - LMTD Method"; |
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242 | Info = |
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243 | "to be documented."; |
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244 | |
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245 | PARAMETERS |
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246 | |
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247 | LMTDcorrection as Switcher(Brief="LMTD Correction Factor Model",Valid=["Bowmann","Fakeri"],Default="Bowmann"); |
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248 | ShellType as Switcher(Brief="TEMA Designation for Shell Type",Valid=["Eshell","Fshell"],Default="Eshell"); |
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249 | |
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250 | VARIABLES |
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251 | |
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252 | Method as LMTD_Basic (Brief="LMTD Method of Calculation", Symbol =" "); |
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253 | R as positive (Brief=" Capacity Ratio for LMTD Correction Fator",Lower=1e-6); |
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254 | P as positive (Brief="Non - Dimensional Variable for LMTD Correction Fator ",Lower=1e-6); |
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255 | Pc as positive (Brief="Non - Dimensional Variable for LMTD Correction Fator when 2 Pass Shell Side",Lower=1e-6); |
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256 | Rho as positive (Brief="Non - Dimensional Variable for LMTD Correction Fator in Fakeri Equation",Lower=1e-6); |
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257 | Phi as positive (Brief="Non - Dimensional Variable for LMTD Correction Fator in Fakeri Equation",Lower=1e-6, Symbol ="\phi"); |
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258 | lambdaN as Real (Brief="Non - Dimensional Variable for LMTD Correction Fator in Fakeri Equation when 2 Pass Shell Side", Symbol ="\lambda _{N}"); |
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259 | lambda1 as Real (Brief="Non - Dimensional Variable for LMTD Correction Fator in Fakeri Equationwhen 2 Pass Shell Side", Symbol ="\lambda _{1}"); |
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260 | |
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261 | EQUATIONS |
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262 | |
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263 | "Exchange Surface Area" |
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264 | Details.Q = Details.Ud*Details.A*Method.LMTD*Method.Fc; |
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265 | |
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266 | "R: Capacity Ratio for LMTD Correction Fator" |
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267 | R*(OutletCold.T - InletCold.T ) = (InletHot.T-OutletHot.T); |
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268 | |
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269 | "P: Non - Dimensional Variable for LMTD Correction Fator" |
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270 | P*(InletHot.T- InletCold.T)= (OutletCold.T-InletCold.T); |
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271 | |
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272 | "Temperature Difference at Inlet" |
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273 | Method.DT0 = InletHot.T - OutletCold.T; |
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274 | |
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275 | "Temperature Difference at Outlet" |
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276 | Method.DTL = OutletHot.T - InletCold.T; |
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277 | |
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278 | switch ShellType |
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279 | |
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280 | case "Fshell": |
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281 | |
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282 | switch LMTDcorrection |
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283 | |
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284 | case "Bowmann": |
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285 | |
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286 | " Variable not in use with Bowmann equation" |
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287 | lambdaN =1; |
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288 | |
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289 | " Variable not in use with Bowmann equation" |
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290 | lambda1 =1; |
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291 | |
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292 | " Variable not in use with Bowmann equation" |
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293 | Phi = 1; |
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294 | |
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295 | " Variable not in use with Bowmann equation" |
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296 | Rho =1; |
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297 | |
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298 | if R equal 1 |
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299 | |
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300 | then |
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301 | |
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302 | "Non Dimensional Variable for LMTD Correction Fator when 2 Pass Shell Side" |
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303 | Pc*(2-P)= P; |
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304 | |
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305 | "LMTD Correction Fator when 2 Pass Shell Side" |
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306 | Method.Fc= (sqrt(2)*Pc)/((1-Pc)*ln( abs( ( 2-Pc*0.585786)/( 2-Pc*3.414214)))); |
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307 | |
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308 | else |
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309 | |
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310 | "Non Dimensional Variable for LMTD Correction Fator when 2 Pass Shell Side" |
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311 | Pc = (sqrt(abs(( 1-P*R)/(1-P)))-1)/(sqrt(abs(( 1-P*R)/(1-P)))-R); |
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312 | |
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313 | "LMTD Correction Fator when 2 Pass Shell Side" |
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314 | Method.Fc = sqrt(R*R+1)*ln(abs((1-Pc*R)/(1-Pc)))/((1-R)*ln( abs( ( 2-Pc*(R+1-sqrt(R*R+1)))/ ( 2-Pc*(R + 1 + sqrt(R*R+1)))))); |
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315 | |
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316 | end |
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317 | |
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318 | case "Fakeri": |
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319 | |
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320 | " Variable not in use with Fakeri equation" |
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321 | Pc = P; |
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322 | |
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323 | "Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation" |
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324 | Rho*(1-P*R) = (1-P); |
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325 | |
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326 | "Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation " |
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327 | Phi = (sqrt(((InletHot.T - OutletHot.T)*(InletHot.T- OutletHot.T))+((OutletCold.T - InletCold.T)*(OutletCold.T - InletCold.T))))/(2*((InletHot.T + OutletHot.T)-( InletCold.T + OutletCold.T))); |
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328 | |
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329 | if Rho equal 1 |
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330 | |
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331 | then |
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332 | |
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333 | " Variable not in use when Rho = 1" |
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334 | lambdaN = 1; |
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335 | |
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336 | " Variable not in use when Rho = 1" |
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337 | lambda1 = 1; |
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338 | |
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339 | "LMTD Correction Fator when 2 Pass Shell Side" |
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340 | Method.Fc = (2*Phi )/(ln(abs((1+Phi )/(1-Phi )))); |
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341 | |
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342 | else |
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343 | |
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344 | "Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation" |
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345 | lambdaN = (1/ln(sqrt(abs(Rho))))*((2*sqrt(abs(Rho))-2)/(sqrt(abs(Rho))+1)); |
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346 | |
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347 | "Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation" |
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348 | lambda1 = (1/ln(abs(Rho)))*((2*Rho-2)/(Rho+1)); |
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349 | |
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350 | "LMTD Correction Fator when 2 Pass Shell Side" |
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351 | Method.Fc = ((2*Phi *(lambdaN/lambda1))/(ln(abs((1+Phi *(lambdaN/lambda1))/(1-Phi *(lambdaN/lambda1))))))*(1/lambdaN); |
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352 | |
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353 | end |
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354 | |
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355 | |
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356 | end |
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357 | |
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358 | case "Eshell": |
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359 | |
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360 | " Variable not in use when 1 Pass Shell Side" |
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361 | lambdaN =1; |
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362 | |
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363 | " Variable not in use when 1 Pass Shell Side" |
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364 | lambda1 =1; |
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365 | |
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366 | " Variable not in use when 1 Pass Shell Side" |
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367 | Pc = P; |
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368 | |
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369 | switch LMTDcorrection |
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370 | |
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371 | case "Bowmann": |
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372 | |
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373 | " Variable not in use with Bowmann equation" |
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374 | Phi = 1; |
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375 | |
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376 | " Variable not in use with Bowmann equation" |
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377 | Rho = 1; |
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378 | |
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379 | |
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380 | if R equal 1 |
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381 | |
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382 | then |
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383 | |
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384 | "LMTD Correction Fator when 1 Pass Shell Side" |
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385 | Method.Fc = (sqrt(2)*P)/((1-P)*ln( abs( ( 2-P*0.585786)/( 2-P*3.414214)))); |
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386 | |
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387 | else |
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388 | |
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389 | "LMTD Correction Fator when 1 Pass Shell Side" |
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390 | Method.Fc = sqrt(R*R+1)*ln(abs((1-P*R)/(1-P)))/((1-R)*ln( abs( ( 2-P*(R+1-sqrt(R*R+1)))/ ( 2-P*(R + 1 + sqrt(R*R+1)))))); |
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391 | |
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392 | end |
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393 | |
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394 | case "Fakeri": |
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395 | |
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396 | "Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation " |
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397 | Phi = (sqrt(((InletHot.T- OutletHot.T)*(InletHot.T- OutletHot.T))+((OutletCold.T - InletCold.T)*(OutletCold.T - InletCold.T))))/(2*((InletHot.T+ OutletHot.T)-(InletCold.T+ OutletCold.T))); |
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398 | |
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399 | "Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation" |
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400 | Rho*(1-P*R) = (1-P); |
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401 | |
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402 | if Rho equal 1 |
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403 | |
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404 | then |
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405 | |
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406 | "LMTD Correction Fator when 1 Pass Shell Side" |
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407 | Method.Fc = (4*Phi)/(ln(abs((1+2*Phi)/(1-2*Phi)))); |
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408 | |
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409 | else |
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410 | |
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411 | "LMTD Correction Fator when 1 Pass Shell Side" |
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412 | Method.Fc = (2*Phi*(Rho+1)*ln(abs(Rho)))/( ln(abs((1+2*Phi)/(1-2*Phi)))*(Rho-1)); |
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413 | |
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414 | end |
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415 | |
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416 | end |
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417 | |
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418 | |
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419 | end |
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420 | |
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421 | end |
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422 | |
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423 | Model HeatExchanger_NTU as HeatExchangerSimplified_Basic |
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424 | |
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425 | ATTRIBUTES |
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426 | Pallete = true; |
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427 | Icon = "icon/HeatExchanger_NTU"; |
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428 | Brief = "Heat Exchanger Block - NTU Method"; |
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429 | Info = |
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430 | "to be documented."; |
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431 | |
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432 | PARAMETERS |
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433 | |
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434 | FlowDirection as Switcher (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent"); |
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435 | |
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436 | VARIABLES |
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437 | |
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438 | Method as NTU_Basic (Brief="NTU Method of Calculation", Symbol =" "); |
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439 | |
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440 | EQUATIONS |
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441 | |
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442 | "Number of Units Transference" |
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443 | Method.NTU*Method.Cmin = Details.Ud*Details.A; |
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444 | |
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445 | "Minimum Heat Capacity" |
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446 | Method.Cmin = min([Method.Ch,Method.Cc]); |
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447 | |
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448 | "Maximum Heat Capacity" |
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449 | Method.Cmax = max([Method.Ch,Method.Cc]); |
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450 | |
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451 | "Thermal Capacity Ratio" |
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452 | Method.Cr = Method.Cmin/Method.Cmax; |
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453 | |
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454 | "Duty" |
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455 | Details.Q = Method.Eft*Method.Cmin*(InletHot.T-InletCold.T); |
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456 | |
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457 | "Hot Stream Heat Capacity" |
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458 | Method.Ch = InletHot.F*HotSide.Properties.Average.Cp; |
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459 | |
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460 | "Cold Stream Heat Capacity" |
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461 | Method.Cc = InletCold.F*ColdSide.Properties.Average.Cp; |
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462 | |
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463 | "Effectiveness Correction" |
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464 | Method.Eft1 = 1; |
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465 | |
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466 | if Method.Cr equal 0 |
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467 | |
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468 | then |
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469 | |
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470 | "Effectiveness" |
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471 | Method.Eft = 1-exp(-Method.NTU); |
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472 | |
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473 | else |
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474 | |
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475 | switch FlowDirection |
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476 | |
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477 | case "cocurrent": |
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478 | |
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479 | "Effectiveness in Cocurrent Flow" |
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480 | Method.Eft = (1-exp(-Method.NTU*(1+Method.Cr)))/(1+Method.Cr); |
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481 | |
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482 | case "counter": |
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483 | |
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484 | if Method.Cr equal 1 |
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485 | |
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486 | then |
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487 | "Effectiveness in Counter Flow" |
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488 | Method.Eft = Method.NTU/(1+Method.NTU); |
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489 | |
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490 | else |
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491 | "Effectiveness in Counter Flow" |
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492 | Method.Eft = (1-exp(-Method.NTU*(1-Method.Cr)))/(1-Method.Cr*exp(-Method.NTU*(1-Method.Cr))); |
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493 | |
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494 | end |
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495 | |
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496 | end |
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497 | |
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498 | |
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499 | end |
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500 | |
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501 | end |
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502 | |
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503 | Model Shell_and_Tubes_NTU as HeatExchangerSimplified_Basic |
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504 | |
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505 | ATTRIBUTES |
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506 | Pallete = true; |
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507 | Icon = "icon/Shell_and_Tubes_NTU"; |
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508 | Brief = "Shell and Tubes Heat Exchanger with 1 or 2 shell pass - NTU Method"; |
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509 | Info = |
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510 | "to be documented."; |
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511 | |
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512 | PARAMETERS |
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513 | |
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514 | ShellType as Switcher (Brief="TEMA Designation",Valid=["Eshell","Fshell"],Default="Eshell"); |
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515 | |
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516 | VARIABLES |
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517 | |
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518 | Method as NTU_Basic (Brief="NTU Method of Calculation" , Symbol =" "); |
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519 | |
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520 | EQUATIONS |
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521 | |
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522 | "Number of Units Transference" |
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523 | Method.NTU*Method.Cmin = Details.Ud*Details.A; |
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524 | |
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525 | "Minimum Heat Capacity" |
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526 | Method.Cmin = min([Method.Ch,Method.Cc]); |
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527 | |
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528 | "Maximum Heat Capacity" |
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529 | Method.Cmax = max([Method.Ch,Method.Cc]); |
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530 | |
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531 | "Thermal Capacity Ratio" |
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532 | Method.Cr = Method.Cmin/Method.Cmax; |
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533 | |
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534 | "Duty" |
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535 | Details.Q = Method.Eft*Method.Cmin*(InletHot.T-InletCold.T); |
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536 | |
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537 | "Hot Stream Heat Capacity" |
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538 | Method.Ch = InletHot.F*HotSide.Properties.Average.Cp; |
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539 | |
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540 | "Cold Stream Heat Capacity" |
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541 | Method.Cc = InletCold.F*ColdSide.Properties.Average.Cp; |
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542 | |
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543 | switch ShellType |
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544 | |
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545 | case "Fshell": |
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546 | |
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547 | "Effectiveness Correction for 2 pass shell side" |
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548 | Method.Eft1 = 2*(1+Method.Cr+sqrt(1+Method.Cr^2)*((1+exp(-Method.NTU*sqrt(1+Method.Cr^2)))/(1-exp(-Method.NTU*sqrt(1+Method.Cr^2)))) )^-1; |
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549 | |
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550 | "TEMA F Shell Effectiveness" |
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551 | Method.Eft = ( ((1-Method.Eft1*Method.Cr)/(1-Method.Eft1))^2 -1 )*( ((1-Method.Eft1*Method.Cr)/(1-Method.Eft1))^2 - Method.Cr )^-1; |
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552 | |
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553 | case "Eshell": |
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554 | |
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555 | "TEMA E Shell Effectiveness" |
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556 | Method.Eft = 2*(1+Method.Cr+sqrt(1+Method.Cr^2)*((1+exp(-Method.NTU*sqrt(1+Method.Cr^2)))/(1-exp(-Method.NTU*sqrt(1+Method.Cr^2)))) )^-1; |
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557 | |
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558 | "Variable not in use when 1 Pass Shell Side" |
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559 | Method.Eft1 = 1; |
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560 | |
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561 | end |
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562 | |
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563 | end |
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