| 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 | * Author: Gerson Balbueno Bicca |
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| 16 | * $Id: DoublePipe.mso 551 2008-07-08 20:51:28Z bicca $ |
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| 17 | *------------------------------------------------------------------*# |
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| 18 | |
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| 19 | using "HEX_Engine"; |
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| 20 | |
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| 21 | Model DoublePipe_Geometry |
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| 22 | |
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| 23 | ATTRIBUTES |
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| 24 | Pallete = false; |
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| 25 | Brief = "double pipe geometrical parameters."; |
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| 26 | |
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| 27 | PARAMETERS |
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| 28 | |
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| 29 | outer PP as Plugin (Brief="External Physical Properties", Type="PP"); |
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| 30 | outer NComp as Integer (Brief="Number of Components",Hidden=true); |
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| 31 | |
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| 32 | M(NComp) as molweight (Brief="Component Mol Weight",Hidden=true); |
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| 33 | |
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| 34 | Pi as constant (Brief="Pi Number",Default=3.14159265, Symbol = "\pi",Hidden=true); |
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| 35 | DoInner as length (Brief="Outside Diameter of Inner Pipe",Lower=1e-6); |
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| 36 | DiInner as length (Brief="Inside Diameter of Inner Pipe",Lower=1e-10); |
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| 37 | DiOuter as length (Brief="Inside Diameter of Outer pipe",Lower=1e-10); |
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| 38 | Lpipe as length (Brief="Effective Tube Length of one segment of Pipe",Lower=0.1, Symbol = "L_{pipe}"); |
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| 39 | Kwall as conductivity (Brief="Tube Wall Material Thermal Conductivity",Default=1.0, Symbol = "K_{wall}"); |
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| 40 | Rfi as positive (Brief="Inside Fouling Resistance",Unit='m^2*K/kW',Default=1e-6,Lower=0); |
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| 41 | Rfo as positive (Brief="Outside Fouling Resistance",Unit='m^2*K/kW',Default=1e-6,Lower=0); |
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| 42 | |
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| 43 | SET |
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| 44 | |
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| 45 | #"Component Molecular Weight" |
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| 46 | M = PP.MolecularWeight(); |
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| 47 | |
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| 48 | #"Pi Number" |
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| 49 | Pi = 3.14159265; |
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| 50 | |
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| 51 | end |
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| 52 | |
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| 53 | Model DoublePipe_Basic |
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| 54 | |
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| 55 | ATTRIBUTES |
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| 56 | Pallete = false; |
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| 57 | Brief = "Basic Equations for rigorous double pipe heat exchanger model."; |
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| 58 | Info = |
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| 59 | "Thermal analysis of double pipe heat exchanger using the NTU or LMTD Method. |
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| 60 | |
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| 61 | == References == |
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| 62 | |
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| 63 | [1] E.A.D. Saunders, Heat Exchangers: Selection, Design and |
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| 64 | Construction, Longman, Harlow, 1988. |
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| 65 | |
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| 66 | [2] Serth, Robert W., Process Heat Transfer: Principles and Applications, Elsevier, 2007. |
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| 67 | |
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| 68 | [3] Gnielinski, V., Forced convection in ducts, in Heat Exchanger Design Handbook, Vol. 2 |
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| 69 | Hemisphere Publishing Corp., New York, 1988."; |
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| 70 | |
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| 71 | PARAMETERS |
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| 72 | |
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| 73 | outer PP as Plugin (Brief="External Physical Properties", Type="PP"); |
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| 74 | outer NComp as Integer (Brief="Number of Components",Hidden=true); |
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| 75 | |
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| 76 | M(NComp) as molweight (Brief="Component Mol Weight",Hidden=true); |
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| 77 | |
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| 78 | HotSide as Switcher (Brief="Flag for Fluid Alocation ",Valid=["outer","inner"],Default="outer",Hidden=true); |
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| 79 | innerFlowRegime as Switcher (Brief="Inner Flow Regime ",Valid=["laminar","transition","turbulent"],Default="laminar",Hidden=true); |
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| 80 | outerFlowRegime as Switcher (Brief="Outer Flow Regime ",Valid=["laminar","transition","turbulent"],Default="laminar",Hidden=true); |
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| 81 | |
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| 82 | InnerLaminarCorrelation as Switcher (Brief="Heat Transfer Correlation in Laminar Flow for the Inner Side",Valid=["Hausen","Schlunder"],Default="Hausen"); |
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| 83 | InnerTransitionCorrelation as Switcher (Brief="Heat Transfer Correlation in Transition Flow for the Inner Side",Valid=["Gnielinski","Hausen"],Default="Gnielinski"); |
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| 84 | InnerTurbulentCorrelation as Switcher (Brief="Heat Transfer Correlation in Turbulent Flow for the Inner Side",Valid=["Petukhov","SiederTate"],Default="Petukhov"); |
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| 85 | |
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| 86 | OuterLaminarCorrelation as Switcher (Brief="Heat Transfer Correlation in Laminar Flow for the Outer Side",Valid=["Hausen","Schlunder"],Default="Hausen"); |
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| 87 | OuterTransitionCorrelation as Switcher (Brief="Heat Transfer Correlation in Transition Flow for the OuterSide",Valid=["Gnielinski","Hausen"],Default="Gnielinski"); |
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| 88 | OuterTurbulentCorrelation as Switcher (Brief="Heat Transfer Correlation in Turbulent Flow for the Outer Side",Valid=["Petukhov","SiederTate"],Default="Petukhov"); |
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| 89 | |
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| 90 | CalculationApproach as Switcher (Brief="Options for convergence Calculations ",Valid=["Simplified","Full"],Default="Full"); |
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| 91 | Qestimated as power (Brief="Estimated Duty", Default=70, Lower=1e-6, Upper=1e10); |
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| 92 | |
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| 93 | VARIABLES |
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| 94 | |
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| 95 | Geometry as DoublePipe_Geometry (Brief="Double pipe geometry",Symbol=" "); |
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| 96 | in InletInner as stream (Brief="Inlet Inner Stream", PosX=0, PosY=0.5225, Symbol="_{inInner}"); |
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| 97 | in InletOuter as stream (Brief="Inlet Outer Stream", PosX=0.2805, PosY=0, Symbol="_{inOuter}"); |
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| 98 | out OutletInner as streamPH (Brief="Outlet Inner Stream", PosX=1, PosY=0.5225, Symbol="_{outInner}"); |
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| 99 | out OutletOuter as streamPH (Brief="Outlet Outer Stream", PosX=0.7264, PosY=1, Symbol="_{outOuter}"); |
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| 100 | |
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| 101 | Details as Details_Main (Brief="Some Details in the Heat Exchanger", Symbol=" "); |
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| 102 | Inner as Main_DoublePipe (Brief="Inner Side of the Heat Exchanger", Symbol="_{Inner}"); |
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| 103 | Outer as Main_DoublePipe (Brief="Outer Side of the Heat Exchanger", Symbol="_{Outer}"); |
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| 104 | |
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| 105 | SET |
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| 106 | |
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| 107 | #"Inner Pipe Cross Sectional Area for Flow" |
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| 108 | Inner.HeatTransfer.As = 0.25*Geometry.Pi*Geometry.DiInner*Geometry.DiInner; |
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| 109 | |
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| 110 | #"Outer Pipe Cross Sectional Area for Flow" |
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| 111 | Outer.HeatTransfer.As = 0.25*Geometry.Pi*(Geometry.DiOuter*Geometry.DiOuter - Geometry.DoInner*Geometry.DoInner); |
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| 112 | |
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| 113 | #"Inner Pipe Hydraulic Diameter for Heat Transfer" |
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| 114 | Inner.HeatTransfer.Dh = Geometry.DiInner; |
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| 115 | |
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| 116 | #"Outer Pipe Hydraulic Diameter for Heat Transfer" |
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| 117 | Outer.HeatTransfer.Dh = (Geometry.DiOuter*Geometry.DiOuter-Geometry.DoInner*Geometry.DoInner)/Geometry.DoInner; |
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| 118 | |
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| 119 | #"Inner Pipe Hydraulic Diameter for Pressure Drop" |
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| 120 | Inner.PressureDrop.Dh = Geometry.DiInner; |
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| 121 | |
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| 122 | #"Outer Pipe Hydraulic Diameter for Pressure Drop" |
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| 123 | Outer.PressureDrop.Dh=Geometry.DiOuter-Geometry.DoInner; |
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| 124 | |
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| 125 | EQUATIONS |
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| 126 | |
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| 127 | "Outer Stream Average Temperature" |
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| 128 | Outer.Properties.Average.T = 0.5*InletOuter.T + 0.5*OutletOuter.T; |
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| 129 | |
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| 130 | "Inner Stream Average Temperature" |
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| 131 | Inner.Properties.Average.T = 0.5*InletInner.T + 0.5*OutletInner.T; |
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| 132 | |
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| 133 | "Outer Stream Average Pressure" |
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| 134 | Outer.Properties.Average.P = 0.5*InletOuter.P+0.5*OutletOuter.P; |
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| 135 | |
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| 136 | "Inner Stream Average Pressure" |
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| 137 | Inner.Properties.Average.P = 0.5*InletInner.P+0.5*OutletInner.P; |
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| 138 | |
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| 139 | "Inner Stream Wall Temperature" |
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| 140 | Inner.Properties.Wall.Twall = 0.5*Outer.Properties.Average.T + 0.5*Inner.Properties.Average.T; |
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| 141 | |
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| 142 | "Outer Stream Wall Temperature" |
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| 143 | Outer.Properties.Wall.Twall = 0.5*Outer.Properties.Average.T + 0.5*Inner.Properties.Average.T; |
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| 144 | |
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| 145 | "Outer Stream Average Molecular Weight" |
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| 146 | Outer.Properties.Average.Mw = sum(M*InletOuter.z); |
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| 147 | |
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| 148 | "Inner Stream Average Molecular Weight" |
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| 149 | Inner.Properties.Average.Mw = sum(M*InletInner.z); |
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| 150 | |
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| 151 | "Flow Mass Inlet Inner Stream" |
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| 152 | Inner.Properties.Inlet.Fw = sum(M*InletInner.z)*InletInner.F; |
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| 153 | |
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| 154 | "Flow Mass Outlet Inner Stream" |
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| 155 | Inner.Properties.Outlet.Fw = sum(M*OutletInner.z)*OutletInner.F; |
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| 156 | |
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| 157 | "Flow Mass Inlet Outer Stream" |
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| 158 | Outer.Properties.Inlet.Fw = sum(M*InletOuter.z)*InletOuter.F; |
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| 159 | |
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| 160 | "Flow Mass Outlet Outer Stream" |
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| 161 | Outer.Properties.Outlet.Fw = sum(M*OutletOuter.z)*OutletOuter.F; |
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| 162 | |
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| 163 | "Molar Balance Outer Stream" |
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| 164 | OutletOuter.F = InletOuter.F; |
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| 165 | |
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| 166 | "Molar Balance Inner Stream" |
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| 167 | OutletInner.F = InletInner.F; |
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| 168 | |
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| 169 | "Outer Stream Molar Fraction Constraint" |
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| 170 | OutletOuter.z=InletOuter.z; |
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| 171 | |
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| 172 | "Inner Stream Molar Fraction Constraint" |
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| 173 | OutletInner.z=InletInner.z; |
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| 174 | |
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| 175 | "Exchange Surface Area for one segment of pipe" |
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| 176 | Details.A=Geometry.Pi*Geometry.DoInner*Geometry.Lpipe; |
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| 177 | |
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| 178 | if InletInner.v equal 0 |
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| 179 | |
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| 180 | then |
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| 181 | |
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| 182 | "Average Heat Capacity Inner Stream" |
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| 183 | Inner.Properties.Average.Cp = PP.LiquidCp(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z); |
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| 184 | |
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| 185 | "Average Mass Density Inner Stream" |
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| 186 | Inner.Properties.Average.rho = PP.LiquidDensity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z); |
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| 187 | |
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| 188 | "Inlet Mass Density Inner Stream" |
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| 189 | Inner.Properties.Inlet.rho = PP.LiquidDensity(InletInner.T,InletInner.P,InletInner.z); |
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| 190 | |
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| 191 | "Outlet Mass Density Inner Stream" |
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| 192 | Inner.Properties.Outlet.rho = PP.LiquidDensity(OutletInner.T,OutletInner.P,OutletInner.z); |
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| 193 | |
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| 194 | "Average Viscosity Inner Stream" |
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| 195 | Inner.Properties.Average.Mu = PP.LiquidViscosity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z); |
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| 196 | |
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| 197 | "Average Conductivity Inner Stream" |
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| 198 | Inner.Properties.Average.K = PP.LiquidThermalConductivity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z); |
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| 199 | |
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| 200 | "Viscosity Inner Stream at wall temperature" |
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| 201 | Inner.Properties.Wall.Mu = PP.LiquidViscosity(Inner.Properties.Wall.Twall,Inner.Properties.Average.P,InletInner.z); |
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| 202 | |
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| 203 | else |
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| 204 | |
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| 205 | "Average Heat Capacity InnerStream" |
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| 206 | Inner.Properties.Average.Cp = PP.VapourCp(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z); |
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| 207 | |
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| 208 | "Average Mass Density Inner Stream" |
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| 209 | Inner.Properties.Average.rho = PP.VapourDensity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z); |
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| 210 | |
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| 211 | "Inlet Mass Density Inner Stream" |
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| 212 | Inner.Properties.Inlet.rho = PP.VapourDensity(InletInner.T,InletInner.P,InletInner.z); |
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| 213 | |
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| 214 | "Outlet Mass Density Inner Stream" |
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| 215 | Inner.Properties.Outlet.rho = PP.VapourDensity(OutletInner.T,OutletInner.P,OutletInner.z); |
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| 216 | |
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| 217 | "Average Viscosity Inner Stream" |
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| 218 | Inner.Properties.Average.Mu = PP.VapourViscosity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z); |
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| 219 | |
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| 220 | "Average Conductivity Inner Stream" |
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| 221 | Inner.Properties.Average.K = PP.VapourThermalConductivity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z); |
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| 222 | |
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| 223 | "Viscosity Inner Stream at wall temperature" |
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| 224 | Inner.Properties.Wall.Mu = PP.VapourViscosity(Inner.Properties.Wall.Twall,Inner.Properties.Average.P,InletInner.z); |
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| 225 | |
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| 226 | end |
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| 227 | |
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| 228 | if InletOuter.v equal 0 |
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| 229 | |
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| 230 | then |
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| 231 | |
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| 232 | "Average Heat Capacity Outer Stream" |
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| 233 | Outer.Properties.Average.Cp = PP.LiquidCp(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z); |
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| 234 | |
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| 235 | "Average Mass Density Outer Stream" |
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| 236 | Outer.Properties.Average.rho = PP.LiquidDensity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z); |
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| 237 | |
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| 238 | "Inlet Mass Density Outer Stream" |
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| 239 | Outer.Properties.Inlet.rho = PP.LiquidDensity(InletOuter.T,InletOuter.P,InletOuter.z); |
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| 240 | |
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| 241 | "Outlet Mass Density Outer Stream" |
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| 242 | Outer.Properties.Outlet.rho = PP.LiquidDensity(OutletOuter.T,OutletOuter.P,OutletOuter.z); |
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| 243 | |
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| 244 | "Average Viscosity Outer Stream" |
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| 245 | Outer.Properties.Average.Mu = PP.LiquidViscosity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z); |
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| 246 | |
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| 247 | "Average Conductivity Outer Stream" |
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| 248 | Outer.Properties.Average.K = PP.LiquidThermalConductivity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z); |
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| 249 | |
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| 250 | "Viscosity Outer Stream at wall temperature" |
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| 251 | Outer.Properties.Wall.Mu = PP.LiquidViscosity(Outer.Properties.Wall.Twall,Outer.Properties.Average.P,InletOuter.z); |
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| 252 | |
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| 253 | |
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| 254 | else |
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| 255 | |
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| 256 | "Average Heat Capacity Outer Stream" |
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| 257 | Outer.Properties.Average.Cp = PP.VapourCp(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z); |
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| 258 | |
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| 259 | "Average Mass Density Outer Stream" |
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| 260 | Outer.Properties.Average.rho = PP.VapourDensity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z); |
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| 261 | |
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| 262 | "Inlet Mass Density Outer Stream" |
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| 263 | Outer.Properties.Inlet.rho = PP.VapourDensity(InletOuter.T,InletOuter.P,InletOuter.z); |
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| 264 | |
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| 265 | "Outlet Mass Density Outer Stream" |
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| 266 | Outer.Properties.Outlet.rho = PP.VapourDensity(OutletOuter.T,OutletOuter.P,OutletOuter.z); |
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| 267 | |
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| 268 | "Average Viscosity Outer Stream" |
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| 269 | Outer.Properties.Average.Mu = PP.VapourViscosity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z); |
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| 270 | |
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| 271 | "Average Conductivity Outer Stream" |
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| 272 | Outer.Properties.Average.K = PP.VapourThermalConductivity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z); |
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| 273 | |
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| 274 | "Viscosity Outer Stream at wall temperature" |
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| 275 | Outer.Properties.Wall.Mu = PP.VapourViscosity(Outer.Properties.Wall.Twall,Outer.Properties.Average.P,InletOuter.z); |
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| 276 | |
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| 277 | end |
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| 278 | |
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| 279 | switch HotSide |
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| 280 | |
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| 281 | case "outer": |
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| 282 | |
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| 283 | "Energy Balance Outer Stream" |
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| 284 | Details.Q = InletOuter.F*(InletOuter.h-OutletOuter.h); |
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| 285 | |
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| 286 | "Energy Balance Inner Stream" |
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| 287 | Details.Q = InletInner.F*(OutletInner.h-InletInner.h); |
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| 288 | |
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| 289 | when InletInner.T > InletOuter.T switchto "inner"; |
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| 290 | |
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| 291 | case "inner": |
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| 292 | |
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| 293 | "Energy Balance Hot Stream" |
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| 294 | Details.Q = InletInner.F*(InletInner.h-OutletInner.h); |
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| 295 | |
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| 296 | "Energy Balance Cold Stream" |
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| 297 | Details.Q = InletOuter.F*(OutletOuter.h - InletOuter.h); |
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| 298 | |
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| 299 | when InletInner.T < InletOuter.T switchto "outer"; |
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| 300 | |
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| 301 | end |
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| 302 | |
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| 303 | switch innerFlowRegime |
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| 304 | |
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| 305 | case "laminar": |
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| 306 | |
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| 307 | "Inner Side Friction Factor for Pressure Drop - laminar Flow" |
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| 308 | Inner.PressureDrop.fi*Inner.PressureDrop.Re = 16; |
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| 309 | |
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| 310 | when Inner.PressureDrop.Re > 2300 switchto "transition"; |
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| 311 | |
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| 312 | case "transition": |
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| 313 | |
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| 314 | "using Turbulent Flow" |
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| 315 | (Inner.PressureDrop.fi-0.0035)*(Inner.PressureDrop.Re^0.42) = 0.264; |
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| 316 | |
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| 317 | when Inner.PressureDrop.Re < 2300 switchto "laminar"; |
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| 318 | when Inner.PressureDrop.Re > 10000 switchto "turbulent"; |
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| 319 | |
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| 320 | case "turbulent": |
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| 321 | |
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| 322 | "Inner Side Friction Factor" |
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| 323 | (Inner.PressureDrop.fi-0.0035)*(Inner.PressureDrop.Re^0.42) = 0.264; |
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| 324 | |
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| 325 | when Inner.PressureDrop.Re < 10000 switchto "transition"; |
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| 326 | |
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| 327 | end |
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| 328 | |
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| 329 | switch outerFlowRegime |
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| 330 | |
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| 331 | case "laminar": |
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| 332 | |
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| 333 | "Outer Side Friction Factor - laminar Flow" |
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| 334 | Outer.PressureDrop.fi*Outer.PressureDrop.Re = 16; |
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| 335 | |
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| 336 | when Outer.PressureDrop.Re > 2300 switchto "transition"; |
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| 337 | |
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| 338 | case "transition": |
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| 339 | |
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| 340 | "using Turbulent Flow" |
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| 341 | (Outer.PressureDrop.fi-0.0035)*(Outer.PressureDrop.Re^0.42) = 0.264; |
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| 342 | |
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| 343 | when Outer.PressureDrop.Re < 2300 switchto "laminar"; |
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| 344 | when Outer.PressureDrop.Re > 10000 switchto "turbulent"; |
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| 345 | |
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| 346 | case "turbulent": |
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| 347 | |
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| 348 | "Outer Side Friction Factor" |
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| 349 | (Outer.PressureDrop.fi-0.0035)*(Outer.PressureDrop.Re^0.42) = 0.264; |
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| 350 | |
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| 351 | when Outer.PressureDrop.Re < 10000 switchto "transition"; |
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| 352 | |
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| 353 | end |
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| 354 | |
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| 355 | switch innerFlowRegime |
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| 356 | |
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| 357 | case "laminar": |
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| 358 | |
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| 359 | "Inner Side Friction Factor for Heat Transfer - laminar Flow" |
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| 360 | Inner.HeatTransfer.fi = 1/(0.79*ln(Inner.HeatTransfer.Re)-1.64)^2; |
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| 361 | |
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| 362 | switch InnerLaminarCorrelation |
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| 363 | |
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| 364 | case "Hausen": |
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| 365 | |
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| 366 | "Nusselt Number" |
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| 367 | Inner.HeatTransfer.Nu = 3.665 + ((0.19*((Geometry.DiInner/Geometry.Lpipe)*Inner.HeatTransfer.Re*Inner.HeatTransfer.PR)^0.8)/(1+0.117*((Geometry.DiInner/Geometry.Lpipe)*Inner.HeatTransfer.Re*Inner.HeatTransfer.PR)^0.467)); |
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| 368 | |
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| 369 | case "Schlunder": |
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| 370 | |
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| 371 | "Nusselt Number" |
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| 372 | Inner.HeatTransfer.Nu = (49.027896+4.173281*Inner.HeatTransfer.Re*Inner.HeatTransfer.PR*(Geometry.DiInner/Geometry.Lpipe))^(1/3); |
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| 373 | |
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| 374 | end |
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| 375 | |
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| 376 | when Inner.HeatTransfer.Re > 2300 switchto "transition"; |
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| 377 | |
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| 378 | case "transition": |
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| 379 | |
|---|
| 380 | "Inner Side Friction Factor for Heat Transfer - transition Flow" |
|---|
| 381 | Inner.HeatTransfer.fi = 1/(0.79*ln(Inner.HeatTransfer.Re)-1.64)^2; |
|---|
| 382 | |
|---|
| 383 | switch InnerTransitionCorrelation |
|---|
| 384 | |
|---|
| 385 | case "Gnielinski": |
|---|
| 386 | |
|---|
| 387 | "Nusselt Number" |
|---|
| 388 | Inner.HeatTransfer.Nu*(1+(12.7*sqrt(0.125*Inner.HeatTransfer.fi)*((Inner.HeatTransfer.PR)^(2/3) -1))) = 0.125*Inner.HeatTransfer.fi*(Inner.HeatTransfer.Re-1000)*Inner.HeatTransfer.PR; |
|---|
| 389 | |
|---|
| 390 | case "Hausen": |
|---|
| 391 | |
|---|
| 392 | "Nusselt Number" |
|---|
| 393 | Inner.HeatTransfer.Nu =0.116*(Inner.HeatTransfer.Re^(0.667)-125)*Inner.HeatTransfer.PR^(0.333)*(1+(Geometry.DiInner/Geometry.Lpipe)^0.667); |
|---|
| 394 | |
|---|
| 395 | end |
|---|
| 396 | |
|---|
| 397 | when Inner.HeatTransfer.Re < 2300 switchto "laminar"; |
|---|
| 398 | when Inner.HeatTransfer.Re > 10000 switchto "turbulent"; |
|---|
| 399 | |
|---|
| 400 | case "turbulent": |
|---|
| 401 | |
|---|
| 402 | switch InnerTurbulentCorrelation |
|---|
| 403 | |
|---|
| 404 | case "Petukhov": |
|---|
| 405 | |
|---|
| 406 | "Inner Side Friction Factor for Heat Transfer - turbulent Flow" |
|---|
| 407 | Inner.HeatTransfer.fi = 1/(1.82*log(Inner.HeatTransfer.Re)-1.64)^2; |
|---|
| 408 | |
|---|
| 409 | "Nusselt Number" |
|---|
| 410 | Inner.HeatTransfer.Nu*(1.07+(12.7*sqrt(0.125*Inner.HeatTransfer.fi)*((Inner.HeatTransfer.PR)^(2/3) -1))) = 0.125*Inner.HeatTransfer.fi*Inner.HeatTransfer.Re*Inner.HeatTransfer.PR; |
|---|
| 411 | |
|---|
| 412 | case "SiederTate": |
|---|
| 413 | |
|---|
| 414 | "Nusselt Number" |
|---|
| 415 | Inner.HeatTransfer.Nu = 0.027*(Inner.HeatTransfer.PR)^(1/3)*(Inner.HeatTransfer.Re)^(4/5); |
|---|
| 416 | |
|---|
| 417 | "Inner Side Friction Factor for Heat Transfer - turbulent Flow" |
|---|
| 418 | Inner.HeatTransfer.fi = 1/(1.82*log(Inner.HeatTransfer.Re)-1.64)^2; |
|---|
| 419 | |
|---|
| 420 | end |
|---|
| 421 | |
|---|
| 422 | when Inner.HeatTransfer.Re < 10000 switchto "transition"; |
|---|
| 423 | |
|---|
| 424 | end |
|---|
| 425 | |
|---|
| 426 | switch outerFlowRegime |
|---|
| 427 | |
|---|
| 428 | case "laminar": |
|---|
| 429 | |
|---|
| 430 | "Outer Side Friction Factor for Heat Transfer - laminar Flow" |
|---|
| 431 | Outer.HeatTransfer.fi = 1/(0.79*ln(Outer.HeatTransfer.Re)-1.64)^2; |
|---|
| 432 | |
|---|
| 433 | switch OuterLaminarCorrelation |
|---|
| 434 | |
|---|
| 435 | case "Hausen": |
|---|
| 436 | |
|---|
| 437 | "Nusselt Number" |
|---|
| 438 | Outer.HeatTransfer.Nu = 3.665 + ((0.19*((Outer.HeatTransfer.Dh/Geometry.Lpipe)*Outer.HeatTransfer.Re*Outer.HeatTransfer.PR)^0.8)/(1+0.117*((Outer.HeatTransfer.Dh/Geometry.Lpipe)*Outer.HeatTransfer.Re*Outer.HeatTransfer.PR)^0.467)); |
|---|
| 439 | |
|---|
| 440 | case "Schlunder": |
|---|
| 441 | |
|---|
| 442 | "Nusselt Number" |
|---|
| 443 | Outer.HeatTransfer.Nu = (49.027896+4.173281*Outer.HeatTransfer.Re*Outer.HeatTransfer.PR*(Outer.HeatTransfer.Dh/Geometry.Lpipe))^(1/3); |
|---|
| 444 | |
|---|
| 445 | end |
|---|
| 446 | |
|---|
| 447 | when Outer.HeatTransfer.Re > 2300 switchto "transition"; |
|---|
| 448 | |
|---|
| 449 | case "transition": |
|---|
| 450 | |
|---|
| 451 | switch OuterTransitionCorrelation |
|---|
| 452 | |
|---|
| 453 | case "Gnielinski": |
|---|
| 454 | |
|---|
| 455 | "Outer Side Friction Factor for Heat Transfer - transition Flow" |
|---|
| 456 | Outer.HeatTransfer.fi = 1/(0.79*ln(Outer.HeatTransfer.Re)-1.64)^2; |
|---|
| 457 | |
|---|
| 458 | "Nusselt Number" |
|---|
| 459 | Outer.HeatTransfer.Nu*(1+(12.7*sqrt(0.125*Outer.HeatTransfer.fi)*((Outer.HeatTransfer.PR)^(2/3) -1))) = 0.125*Outer.HeatTransfer.fi*(Outer.HeatTransfer.Re-1000)*Outer.HeatTransfer.PR; |
|---|
| 460 | |
|---|
| 461 | case "Hausen": |
|---|
| 462 | |
|---|
| 463 | "Nusselt Number" |
|---|
| 464 | Outer.HeatTransfer.Nu = 0.116*(Outer.HeatTransfer.Re^(0.667)-125)*Outer.HeatTransfer.PR^(0.333)*(1+(Outer.HeatTransfer.Dh/Geometry.Lpipe)^0.667); |
|---|
| 465 | |
|---|
| 466 | |
|---|
| 467 | "Outer Side Friction Factor for Heat Transfer - transition Flow" |
|---|
| 468 | Outer.HeatTransfer.fi = 1/(0.79*ln(Outer.HeatTransfer.Re)-1.64)^2; |
|---|
| 469 | |
|---|
| 470 | end |
|---|
| 471 | |
|---|
| 472 | when Outer.HeatTransfer.Re < 2300 switchto "laminar"; |
|---|
| 473 | when Outer.HeatTransfer.Re > 10000 switchto "turbulent"; |
|---|
| 474 | |
|---|
| 475 | case "turbulent": |
|---|
| 476 | |
|---|
| 477 | switch OuterTurbulentCorrelation |
|---|
| 478 | |
|---|
| 479 | case "Petukhov": |
|---|
| 480 | |
|---|
| 481 | "Outer Side Friction Factor for Heat Transfer - turbulent Flow" |
|---|
| 482 | Outer.HeatTransfer.fi = 1/(1.82*log(Outer.HeatTransfer.Re)-1.64)^2; |
|---|
| 483 | |
|---|
| 484 | "Nusselt Number" |
|---|
| 485 | Outer.HeatTransfer.Nu*(1.07+(12.7*sqrt(0.125*Outer.HeatTransfer.fi)*((Outer.HeatTransfer.PR)^(2/3) -1))) = 0.125*Outer.HeatTransfer.fi*Outer.HeatTransfer.Re*Outer.HeatTransfer.PR; |
|---|
| 486 | |
|---|
| 487 | case "SiederTate": |
|---|
| 488 | |
|---|
| 489 | "Nusselt Number" |
|---|
| 490 | Outer.HeatTransfer.Nu = 0.027*(Outer.HeatTransfer.PR)^(1/3)*(Outer.HeatTransfer.Re)^(4/5); |
|---|
| 491 | |
|---|
| 492 | "Outer Side Friction Factor for Heat Transfer - turbulent Flow" |
|---|
| 493 | Outer.HeatTransfer.fi = 1/(1.82*log(Outer.HeatTransfer.Re)-1.64)^2; |
|---|
| 494 | |
|---|
| 495 | end |
|---|
| 496 | |
|---|
| 497 | when Outer.HeatTransfer.Re < 10000 switchto "transition"; |
|---|
| 498 | |
|---|
| 499 | end |
|---|
| 500 | |
|---|
| 501 | switch CalculationApproach |
|---|
| 502 | |
|---|
| 503 | case "Full": |
|---|
| 504 | |
|---|
| 505 | "Total Pressure Drop Outer Stream" |
|---|
| 506 | Outer.PressureDrop.Pdrop = Outer.PressureDrop.Pd_fric; |
|---|
| 507 | |
|---|
| 508 | "Total Pressure Drop Inner Stream" |
|---|
| 509 | Inner.PressureDrop.Pdrop = Inner.PressureDrop.Pd_fric; |
|---|
| 510 | |
|---|
| 511 | "Pressure Drop Outer Stream" |
|---|
| 512 | OutletOuter.P = InletOuter.P - Outer.PressureDrop.Pdrop; |
|---|
| 513 | |
|---|
| 514 | "Pressure Drop Inner Stream" |
|---|
| 515 | OutletInner.P = InletInner.P - Inner.PressureDrop.Pdrop; |
|---|
| 516 | |
|---|
| 517 | "Outer Pipe Pressure Drop for friction" |
|---|
| 518 | Outer.PressureDrop.Pd_fric = (2*Outer.PressureDrop.fi*Geometry.Lpipe*Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean^2)/(Outer.PressureDrop.Dh*Outer.HeatTransfer.Phi); |
|---|
| 519 | |
|---|
| 520 | "Inner Pipe Pressure Drop for friction" |
|---|
| 521 | Inner.PressureDrop.Pd_fric = (2*Inner.PressureDrop.fi*Geometry.Lpipe*Inner.Properties.Average.rho*Inner.HeatTransfer.Vmean^2)/(Geometry.DiInner*Inner.HeatTransfer.Phi); |
|---|
| 522 | |
|---|
| 523 | case "Simplified": |
|---|
| 524 | |
|---|
| 525 | "Total Pressure Drop Outer Stream" |
|---|
| 526 | Outer.PressureDrop.Pdrop = Outer.PressureDrop.Pd_fric; |
|---|
| 527 | |
|---|
| 528 | "Total Pressure Drop Inner Stream" |
|---|
| 529 | Inner.PressureDrop.Pdrop = Inner.PressureDrop.Pd_fric; |
|---|
| 530 | |
|---|
| 531 | "Pressure Drop Outer Stream" |
|---|
| 532 | OutletOuter.P = InletOuter.P - Outer.PressureDrop.Pdrop; |
|---|
| 533 | |
|---|
| 534 | "Pressure Drop Inner Stream" |
|---|
| 535 | OutletInner.P = InletInner.P - Inner.PressureDrop.Pdrop; |
|---|
| 536 | |
|---|
| 537 | "Outer Pipe Pressure Drop for friction" |
|---|
| 538 | Outer.PressureDrop.Pd_fric = 0.01*InletOuter.P; |
|---|
| 539 | |
|---|
| 540 | "Inner Pipe Pressure Drop for friction" |
|---|
| 541 | Inner.PressureDrop.Pd_fric = 0.01*InletInner.P; |
|---|
| 542 | |
|---|
| 543 | end |
|---|
| 544 | |
|---|
| 545 | "Inner Pipe Film Coefficient" |
|---|
| 546 | Inner.HeatTransfer.hcoeff = (Inner.HeatTransfer.Nu*Inner.Properties.Average.K/Geometry.DiInner)*Inner.HeatTransfer.Phi; |
|---|
| 547 | |
|---|
| 548 | "Outer Pipe Film Coefficient" |
|---|
| 549 | Outer.HeatTransfer.hcoeff= (Outer.HeatTransfer.Nu*Outer.Properties.Average.K/Outer.HeatTransfer.Dh)*Outer.HeatTransfer.Phi; |
|---|
| 550 | |
|---|
| 551 | "Outer Pipe Pressure Drop due to return" |
|---|
| 552 | Outer.PressureDrop.Pd_ret = 0*'kPa'; |
|---|
| 553 | |
|---|
| 554 | "Inner Pipe Pressure Drop due to return" |
|---|
| 555 | Inner.PressureDrop.Pd_ret = 0*'kPa'; |
|---|
| 556 | |
|---|
| 557 | "Outer Pipe Phi correction" |
|---|
| 558 | Outer.HeatTransfer.Phi = (Outer.Properties.Average.Mu/Outer.Properties.Wall.Mu)^0.14; |
|---|
| 559 | |
|---|
| 560 | "Inner Pipe Phi correction" |
|---|
| 561 | Inner.HeatTransfer.Phi = (Inner.Properties.Average.Mu/Inner.Properties.Wall.Mu)^0.14; |
|---|
| 562 | |
|---|
| 563 | "Outer Pipe Prandtl Number" |
|---|
| 564 | Outer.HeatTransfer.PR = ((Outer.Properties.Average.Cp/Outer.Properties.Average.Mw)*Outer.Properties.Average.Mu)/Outer.Properties.Average.K; |
|---|
| 565 | |
|---|
| 566 | "Inner Pipe Prandtl Number" |
|---|
| 567 | Inner.HeatTransfer.PR = ((Inner.Properties.Average.Cp/Inner.Properties.Average.Mw)*Inner.Properties.Average.Mu)/Inner.Properties.Average.K; |
|---|
| 568 | |
|---|
| 569 | "Outer Pipe Reynolds Number for Heat Transfer" |
|---|
| 570 | Outer.HeatTransfer.Re = (Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean*Outer.HeatTransfer.Dh)/Outer.Properties.Average.Mu; |
|---|
| 571 | |
|---|
| 572 | "Outer Pipe Reynolds Number for Pressure Drop" |
|---|
| 573 | Outer.PressureDrop.Re = (Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean*Outer.PressureDrop.Dh)/Outer.Properties.Average.Mu; |
|---|
| 574 | |
|---|
| 575 | "Inner Pipe Reynolds Number for Heat Transfer" |
|---|
| 576 | Inner.HeatTransfer.Re = (Inner.Properties.Average.rho*Inner.HeatTransfer.Vmean*Inner.HeatTransfer.Dh)/Inner.Properties.Average.Mu; |
|---|
| 577 | |
|---|
| 578 | "Inner Pipe Reynolds Number for Pressure Drop" |
|---|
| 579 | Inner.PressureDrop.Re = Inner.HeatTransfer.Re; |
|---|
| 580 | |
|---|
| 581 | "Outer Pipe Velocity" |
|---|
| 582 | Outer.HeatTransfer.Vmean*(Outer.HeatTransfer.As*Outer.Properties.Average.rho) = Outer.Properties.Inlet.Fw; |
|---|
| 583 | |
|---|
| 584 | "Inner Pipe Velocity" |
|---|
| 585 | Inner.HeatTransfer.Vmean*(Inner.HeatTransfer.As*Inner.Properties.Average.rho) = Inner.Properties.Inlet.Fw; |
|---|
| 586 | |
|---|
| 587 | "Overall Heat Transfer Coefficient Clean" |
|---|
| 588 | Details.Uc*((Geometry.DoInner/(Inner.HeatTransfer.hcoeff*Geometry.DiInner) )+(Geometry.DoInner*ln(Geometry.DoInner/Geometry.DiInner)/(2*Geometry.Kwall))+(1/(Outer.HeatTransfer.hcoeff)))=1; |
|---|
| 589 | |
|---|
| 590 | "Overall Heat Transfer Coefficient Dirty" |
|---|
| 591 | Details.Ud*(Geometry.Rfi*(Geometry.DoInner/Geometry.DiInner) + Geometry.Rfo + (Geometry.DoInner/(Inner.HeatTransfer.hcoeff*Geometry.DiInner) )+(Geometry.DoInner*ln(Geometry.DoInner/Geometry.DiInner)/(2*Geometry.Kwall))+(1/(Outer.HeatTransfer.hcoeff)))=1; |
|---|
| 592 | |
|---|
| 593 | end |
|---|
| 594 | |
|---|
| 595 | Model DoublePipe_NTU as DoublePipe_Basic |
|---|
| 596 | |
|---|
| 597 | ATTRIBUTES |
|---|
| 598 | |
|---|
| 599 | Icon = "icon/DoublePipe"; |
|---|
| 600 | Pallete = true; |
|---|
| 601 | Brief = "Double Pipe Heat Exchanger - NTU Method"; |
|---|
| 602 | Info = |
|---|
| 603 | "Thermal analysis of double pipe heat exchanger using the NTU Method. |
|---|
| 604 | |
|---|
| 605 | == Specify == |
|---|
| 606 | * The Inlet Inner stream |
|---|
| 607 | * The Inlet Outer stream |
|---|
| 608 | == Setting Parameters == |
|---|
| 609 | * Flow Direction: |
|---|
| 610 | ** counter flow |
|---|
| 611 | ** cocurrent flow (Default) |
|---|
| 612 | * Heat Transfer Correlations: |
|---|
| 613 | ** Laminar flow |
|---|
| 614 | *** Hausen (Default) |
|---|
| 615 | *** Schlunder |
|---|
| 616 | ** Transition flow |
|---|
| 617 | *** Gnielinski (Default) |
|---|
| 618 | *** Hausen |
|---|
| 619 | ** Turbulent flow |
|---|
| 620 | *** Petukhov (Default) |
|---|
| 621 | *** Sieder Tate |
|---|
| 622 | * Geometrical Parameters: |
|---|
| 623 | ** DoInner - Outside Diameter of Inner Pipe |
|---|
| 624 | ** DiInner - Inside Diameter of Inner Pipe |
|---|
| 625 | ** DiOuter - Inside Diameter of Outer pipe |
|---|
| 626 | ** Lpipe - Effective Tube Length of one segment of Pipe |
|---|
| 627 | ** Kwall - Tube Wall Material Thermal Conductivity |
|---|
| 628 | * Fouling: |
|---|
| 629 | **Rfi - Inside Fouling Resistance |
|---|
| 630 | **Rfo - Outside Fouling Resistance |
|---|
| 631 | "; |
|---|
| 632 | |
|---|
| 633 | PARAMETERS |
|---|
| 634 | |
|---|
| 635 | FlowDirection as Switcher (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent"); |
|---|
| 636 | Eftestimated as positive (Brief="Effectiveness estimate",Default=0.5); |
|---|
| 637 | |
|---|
| 638 | VARIABLES |
|---|
| 639 | |
|---|
| 640 | Method as NTU_Basic (Brief="NTU Method of Calculation", Symbol=" "); |
|---|
| 641 | |
|---|
| 642 | EQUATIONS |
|---|
| 643 | |
|---|
| 644 | "Effectiveness Correction" |
|---|
| 645 | Method.Eft1 = 1; |
|---|
| 646 | |
|---|
| 647 | switch CalculationApproach |
|---|
| 648 | |
|---|
| 649 | case "Full": |
|---|
| 650 | |
|---|
| 651 | "Number of Units Transference" |
|---|
| 652 | Method.NTU*Method.Cmin = Details.Ud*Geometry.Pi*Geometry.DoInner*Geometry.Lpipe; |
|---|
| 653 | |
|---|
| 654 | "Minimum Heat Capacity" |
|---|
| 655 | Method.Cmin = min([Method.Ch,Method.Cc]); |
|---|
| 656 | |
|---|
| 657 | "Maximum Heat Capacity" |
|---|
| 658 | Method.Cmax = max([Method.Ch,Method.Cc]); |
|---|
| 659 | |
|---|
| 660 | "Thermal Capacity Ratio" |
|---|
| 661 | Method.Cr = Method.Cmin/Method.Cmax; |
|---|
| 662 | |
|---|
| 663 | if Method.Cr equal 0 |
|---|
| 664 | |
|---|
| 665 | then |
|---|
| 666 | "Effectiveness" |
|---|
| 667 | Method.Eft = 1-exp(-Method.NTU); |
|---|
| 668 | |
|---|
| 669 | else |
|---|
| 670 | |
|---|
| 671 | switch FlowDirection |
|---|
| 672 | |
|---|
| 673 | case "cocurrent": |
|---|
| 674 | |
|---|
| 675 | "Effectiveness in Cocurrent Flow" |
|---|
| 676 | Method.Eft = (1-exp(-Method.NTU*(1+Method.Cr)))/(1+Method.Cr); |
|---|
| 677 | |
|---|
| 678 | case "counter": |
|---|
| 679 | |
|---|
| 680 | if Method.Cr equal 1 |
|---|
| 681 | |
|---|
| 682 | then |
|---|
| 683 | |
|---|
| 684 | "Effectiveness in Counter Flow" |
|---|
| 685 | Method.Eft = Method.NTU/(1+Method.NTU); |
|---|
| 686 | |
|---|
| 687 | else |
|---|
| 688 | |
|---|
| 689 | "Effectiveness in Counter Flow" |
|---|
| 690 | Method.Eft = (1-exp(-Method.NTU*(1-Method.Cr)))/(1-Method.Cr*exp(-Method.NTU*(1-Method.Cr))); |
|---|
| 691 | |
|---|
| 692 | end |
|---|
| 693 | |
|---|
| 694 | end |
|---|
| 695 | |
|---|
| 696 | end |
|---|
| 697 | |
|---|
| 698 | case "Simplified": |
|---|
| 699 | |
|---|
| 700 | "Number of Units Transference" |
|---|
| 701 | Method.NTU = 1; |
|---|
| 702 | |
|---|
| 703 | "Minimum Heat Capacity" |
|---|
| 704 | Method.Cmin = min([Method.Ch,Method.Cc]); |
|---|
| 705 | |
|---|
| 706 | "Maximum Heat Capacity" |
|---|
| 707 | Method.Cmax = max([Method.Ch,Method.Cc]); |
|---|
| 708 | |
|---|
| 709 | "Thermal Capacity Ratio" |
|---|
| 710 | Method.Cr = 1; |
|---|
| 711 | |
|---|
| 712 | "Effectiveness" |
|---|
| 713 | Method.Eft = Eftestimated; |
|---|
| 714 | |
|---|
| 715 | end |
|---|
| 716 | |
|---|
| 717 | switch HotSide |
|---|
| 718 | |
|---|
| 719 | case "outer": |
|---|
| 720 | |
|---|
| 721 | switch CalculationApproach |
|---|
| 722 | |
|---|
| 723 | case "Full": |
|---|
| 724 | |
|---|
| 725 | "Duty" |
|---|
| 726 | Details.Q = Method.Eft*Method.Cmin*(InletOuter.T-InletInner.T); |
|---|
| 727 | |
|---|
| 728 | case "Simplified": |
|---|
| 729 | |
|---|
| 730 | "Duty" |
|---|
| 731 | Details.Q = Qestimated; |
|---|
| 732 | |
|---|
| 733 | end |
|---|
| 734 | |
|---|
| 735 | "Hot Stream Heat Capacity" |
|---|
| 736 | Method.Ch = InletOuter.F*Outer.Properties.Average.Cp; |
|---|
| 737 | |
|---|
| 738 | "Cold Stream Heat Capacity" |
|---|
| 739 | Method.Cc = InletInner.F*Inner.Properties.Average.Cp; |
|---|
| 740 | |
|---|
| 741 | when InletInner.T > InletOuter.T switchto "inner"; |
|---|
| 742 | |
|---|
| 743 | case "inner": |
|---|
| 744 | |
|---|
| 745 | switch CalculationApproach |
|---|
| 746 | |
|---|
| 747 | case "Full": |
|---|
| 748 | |
|---|
| 749 | "Duty" |
|---|
| 750 | Details.Q = Method.Eft*Method.Cmin*(InletInner.T-InletOuter.T); |
|---|
| 751 | |
|---|
| 752 | case "Simplified": |
|---|
| 753 | |
|---|
| 754 | "Duty" |
|---|
| 755 | Details.Q = Qestimated; |
|---|
| 756 | |
|---|
| 757 | end |
|---|
| 758 | |
|---|
| 759 | "Cold Stream Heat Capacity" |
|---|
| 760 | Method.Cc = InletOuter.F*Outer.Properties.Average.Cp; |
|---|
| 761 | |
|---|
| 762 | "Hot Stream Heat Capacity" |
|---|
| 763 | Method.Ch = InletInner.F*Inner.Properties.Average.Cp; |
|---|
| 764 | |
|---|
| 765 | when InletInner.T < InletOuter.T switchto "outer"; |
|---|
| 766 | |
|---|
| 767 | end |
|---|
| 768 | |
|---|
| 769 | end |
|---|
| 770 | |
|---|
| 771 | Model DoublePipe_LMTD as DoublePipe_Basic |
|---|
| 772 | |
|---|
| 773 | ATTRIBUTES |
|---|
| 774 | |
|---|
| 775 | Icon = "icon/DoublePipe"; |
|---|
| 776 | Pallete = true; |
|---|
| 777 | Brief = "Double Pipe Heat Exchanger - LMTD Method"; |
|---|
| 778 | Info = |
|---|
| 779 | "Thermal analysis of double pipe heat exchanger using the LMTD Method. |
|---|
| 780 | |
|---|
| 781 | == Specify == |
|---|
| 782 | * The Inlet Inner stream |
|---|
| 783 | * The Inlet Outer stream |
|---|
| 784 | == Setting Parameters == |
|---|
| 785 | * Flow Direction: |
|---|
| 786 | ** counter flow |
|---|
| 787 | ** cocurrent flow (Default) |
|---|
| 788 | * Heat Transfer Correlations: |
|---|
| 789 | ** Laminar flow |
|---|
| 790 | *** Hausen (Default) |
|---|
| 791 | *** Schlunder |
|---|
| 792 | ** Transition flow |
|---|
| 793 | *** Gnielinski (Default) |
|---|
| 794 | *** Hausen |
|---|
| 795 | ** Turbulent flow |
|---|
| 796 | *** Petukhov (Default) |
|---|
| 797 | *** Sieder Tate |
|---|
| 798 | * Geometrical Parameters: |
|---|
| 799 | ** DoInner - Outside Diameter of Inner Pipe |
|---|
| 800 | ** DiInner - Inside Diameter of Inner Pipe |
|---|
| 801 | ** DiOuter - Inside Diameter of Outer pipe |
|---|
| 802 | ** Lpipe - Effective Tube Length of one segment of Pipe |
|---|
| 803 | ** Kwall - Tube Wall Material Thermal Conductivity |
|---|
| 804 | * Fouling: |
|---|
| 805 | **Rfi - Inside Fouling Resistance |
|---|
| 806 | **Rfo - Outside Fouling Resistance |
|---|
| 807 | "; |
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| 808 | |
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| 809 | PARAMETERS |
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| 810 | |
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| 811 | FlowDirection as Switcher (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent"); |
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| 812 | |
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| 813 | VARIABLES |
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| 814 | |
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| 815 | Method as LMTD_Basic (Brief="LMTD Method of Calculation", Symbol=" "); |
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| 816 | |
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| 817 | EQUATIONS |
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| 818 | |
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| 819 | switch CalculationApproach |
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| 820 | |
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| 821 | case "Full": |
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| 822 | |
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| 823 | "Duty" |
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| 824 | Details.Q = Details.Ud*Geometry.Pi*Geometry.DoInner*Geometry.Lpipe*Method.LMTD; |
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| 825 | |
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| 826 | case "Simplified": |
|---|
| 827 | |
|---|
| 828 | "Duty" |
|---|
| 829 | Details.Q = Qestimated; |
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| 830 | |
|---|
| 831 | end |
|---|
| 832 | |
|---|
| 833 | "LMTD Correction Factor - True counter ou cocurrent flow" |
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| 834 | Method.Fc = 1; |
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| 835 | |
|---|
| 836 | switch HotSide |
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| 837 | |
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| 838 | case "outer": |
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| 839 | |
|---|
| 840 | switch FlowDirection |
|---|
| 841 | |
|---|
| 842 | case "cocurrent": |
|---|
| 843 | |
|---|
| 844 | "Temperature Difference at Inlet - Cocurrent Flow" |
|---|
| 845 | Method.DT0 = InletOuter.T - InletInner.T; |
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| 846 | |
|---|
| 847 | "Temperature Difference at Outlet - Cocurrent Flow" |
|---|
| 848 | Method.DTL = OutletOuter.T - OutletInner.T; |
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| 849 | |
|---|
| 850 | case "counter": |
|---|
| 851 | |
|---|
| 852 | "Temperature Difference at Inlet - Counter Flow" |
|---|
| 853 | Method.DT0 = InletOuter.T - OutletInner.T; |
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| 854 | |
|---|
| 855 | "Temperature Difference at Outlet - Counter Flow" |
|---|
| 856 | Method.DTL = OutletOuter.T - InletInner.T; |
|---|
| 857 | |
|---|
| 858 | |
|---|
| 859 | end |
|---|
| 860 | |
|---|
| 861 | when InletInner.T > InletOuter.T switchto "inner"; |
|---|
| 862 | |
|---|
| 863 | case "inner": |
|---|
| 864 | |
|---|
| 865 | switch FlowDirection |
|---|
| 866 | |
|---|
| 867 | case "cocurrent": |
|---|
| 868 | |
|---|
| 869 | "Temperature Difference at Inlet - Cocurrent Flow" |
|---|
| 870 | Method.DT0 = InletInner.T - InletOuter.T; |
|---|
| 871 | |
|---|
| 872 | "Temperature Difference at Outlet - Cocurrent Flow" |
|---|
| 873 | Method.DTL = OutletInner.T - OutletOuter.T; |
|---|
| 874 | |
|---|
| 875 | case "counter": |
|---|
| 876 | |
|---|
| 877 | "Temperature Difference at Inlet - Counter Flow" |
|---|
| 878 | Method.DT0 = InletInner.T - OutletOuter.T; |
|---|
| 879 | |
|---|
| 880 | "Temperature Difference at Outlet - Counter Flow" |
|---|
| 881 | Method.DTL = OutletInner.T - InletOuter.T; |
|---|
| 882 | |
|---|
| 883 | end |
|---|
| 884 | |
|---|
| 885 | when InletInner.T < InletOuter.T switchto "outer"; |
|---|
| 886 | |
|---|
| 887 | end |
|---|
| 888 | |
|---|
| 889 | end |
|---|
