source: trunk/eml/heat_exchangers/Hairpin.mso @ 473

Last change on this file since 473 was 441, checked in by gerson bicca, 15 years ago

updated Hairpin model
File size: 22.9 KB
Line 
1#*-------------------------------------------------------------------
2* EMSO Model Library (EML) Copyright (C) 2004 - 2007 ALSOC.
3*
4* This LIBRARY is free software; you can distribute it and/or modify
5* it under the therms of the ALSOC FREE LICENSE as available at
6* http://www.enq.ufrgs.br/alsoc.
7*
8* EMSO Copyright (C) 2004 - 2007 ALSOC, original code
9* from http://www.rps.eng.br Copyright (C) 2002-2004.
10* All rights reserved.
11*
12* EMSO is distributed under the therms of the ALSOC LICENSE as
13* available at http://www.enq.ufrgs.br/alsoc.
14*--------------------------------------------------------------------
15* Author: Gerson Balbueno Bicca
16* $Id: Hairpin.mso  Z bicca $
17*------------------------------------------------------------------*#
18
19using "HEX_Engine";
20
21Model Hairpin_Basic
22
23ATTRIBUTES
24        Pallete         = false;
25        Brief           = "Basic Equations for hairpin heat exchanger model.";
26        Info            =
27        "to be documented.";
28
29PARAMETERS
30
31outer PP            as Plugin           (Brief="External Physical Properties", Type="PP");
32outer NComp     as Integer      (Brief="Number of Components");
33       
34        M(NComp)        as molweight    (Brief="Component Mol Weight");
35       
36        HotSide                         as Switcher             (Brief="Flag for Fluid Alocation ",Valid=["outer","inner"],Default="outer");
37        innerFlowRegime         as Switcher     (Brief="Inner Flow Regime ",Valid=["laminar","transition","turbulent"],Default="laminar");
38        outerFlowRegime         as Switcher     (Brief="Outer Flow Regime ",Valid=["laminar","transition","turbulent"],Default="laminar");
39
40        InnerLaminarCorrelation         as Switcher     (Brief="Heat Transfer Correlation in Laminar Flow for the Inner Side",Valid=["Hausen","Schlunder"],Default="Hausen");
41        InnerTransitionCorrelation  as Switcher         (Brief="Heat Transfer Correlation in Transition Flow for the Inner Side",Valid=["Gnielinski","Hausen"],Default="Gnielinski");
42        InnerTurbulentCorrelation   as Switcher (Brief="Heat Transfer Correlation in Turbulent Flow for the Inner Side",Valid=["Petukhov","SiederTate"],Default="Petukhov");
43
44        OuterLaminarCorrelation         as Switcher             (Brief="Heat Transfer Correlation in Laminar Flow for the Outer Side",Valid=["Hausen","Schlunder"],Default="Hausen");
45        OuterTransitionCorrelation  as Switcher         (Brief="Heat Transfer Correlation in Transition Flow for the OuterSide",Valid=["Gnielinski","Hausen"],Default="Gnielinski");
46        OuterTurbulentCorrelation   as Switcher         (Brief="Heat Transfer Correlation in Turbulent Flow for the Outer Side",Valid=["Petukhov","SiederTate"],Default="Petukhov");
47
48        Pi                              as constant             (Brief="Pi Number",Default=3.14159265, Symbol = "\pi");
49        DoInner         as length                       (Brief="Outside Diameter of Inner Pipe",Lower=1e-6);
50        DiInner as length                       (Brief="Inside Diameter of Inner Pipe",Lower=1e-10);
51        DiOuter as length                       (Brief="Inside Diameter of Outer pipe",Lower=1e-10);
52        Lpipe           as length                       (Brief="Effective Tube Length of one segment of Pipe",Lower=0.1, Symbol = "L_{pipe}");
53        Kwall           as conductivity         (Brief="Tube Wall Material Thermal Conductivity",Default=1.0, Symbol = "K_{wall}");
54        Rfi                     as positive                     (Brief="Inside Fouling Resistance",Unit='m^2*K/kW',Default=1e-6,Lower=0);
55        Rfo                     as positive                     (Brief="Outside Fouling Resistance",Unit='m^2*K/kW',Default=1e-6,Lower=0);
56
57VARIABLES
58
59in  InletInner          as stream               (Brief="Inlet Inner Stream", PosX=1, PosY=0.7, Symbol="_{inInner}");   
60in  InletOuter          as stream               (Brief="Inlet Outer Stream", PosX=0.8, PosY=0, Symbol="_{inOuter}");
61out OutletInner         as streamPH     (Brief="Outlet Inner Stream", PosX=1, PosY=0.3, Symbol="_{outInner}");
62out OutletOuter         as streamPH     (Brief="Outlet Outer Stream", PosX=0.8, PosY=1, Symbol="_{outOuter}");
63
64        Details         as Details_Main         (Brief="Some Details in the Heat Exchanger", Symbol=" ");
65        Inner                   as Main_DoublePipe      (Brief="Inner Side of the Heat Exchanger", Symbol="_{Inner}");
66        Outer                   as Main_DoublePipe      (Brief="Outer Side of the Heat Exchanger", Symbol="_{Outer}");
67
68SET
69
70#"Component Molecular Weight"
71        M  = PP.MolecularWeight();
72       
73#"Pi Number"
74        Pi      = 3.14159265;
75       
76#"Inner Pipe Cross Sectional Area for Flow"
77        Inner.HeatTransfer.As=Pi*DiInner*DiInner/4;
78       
79#"Outer Pipe Cross Sectional Area for Flow"
80        Outer.HeatTransfer.As=Pi*(DiOuter*DiOuter - DoInner*DoInner)/4;
81       
82#"Inner Pipe Hydraulic Diameter for Heat Transfer"
83        Inner.HeatTransfer.Dh=DiInner;
84       
85#"Outer Pipe Hydraulic Diameter for Heat Transfer"
86        Outer.HeatTransfer.Dh=(DiOuter*DiOuter-DoInner*DoInner)/DoInner;
87
88#"Inner Pipe Hydraulic Diameter for Pressure Drop"
89        Inner.PressureDrop.Dh=DiInner;
90       
91#"Outer Pipe Hydraulic Diameter for Pressure Drop"
92        Outer.PressureDrop.Dh=DiOuter-DoInner;
93
94EQUATIONS
95
96"Outer  Stream Average Temperature"
97        Outer.Properties.Average.T = 0.5*InletOuter.T + 0.5*OutletOuter.T;
98
99"Inner Stream Average Temperature"
100        Inner.Properties.Average.T = 0.5*InletInner.T + 0.5*OutletInner.T;
101       
102"Outer Stream Average Pressure"
103        Outer.Properties.Average.P = 0.5*InletOuter.P+0.5*OutletOuter.P;
104       
105"Inner Stream Average Pressure"
106        Inner.Properties.Average.P = 0.5*InletInner.P+0.5*OutletInner.P;
107
108"Inner Stream Wall Temperature"
109        Inner.Properties.Wall.Twall =   0.5*Outer.Properties.Average.T + 0.5*Inner.Properties.Average.T;
110
111"Outer Stream Wall Temperature"
112        Outer.Properties.Wall.Twall =   0.5*Outer.Properties.Average.T + 0.5*Inner.Properties.Average.T;
113
114"Outer Stream Average Molecular Weight"
115        Outer.Properties.Average.Mw = sum(M*InletOuter.z);
116
117"Inner Stream Average Molecular Weight"
118        Inner.Properties.Average.Mw = sum(M*InletInner.z);
119
120if InletInner.v equal 0
121       
122        then   
123
124"Average Heat Capacity Inner Stream"
125        Inner.Properties.Average.Cp             =       PP.LiquidCp(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
126
127"Average Mass Density Inner Stream"
128        Inner.Properties.Average.rho    =       PP.LiquidDensity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
129
130"Inlet Mass Density Inner Stream"
131        Inner.Properties.Inlet.rho              =       PP.LiquidDensity(InletInner.T,InletInner.P,InletInner.z);
132
133"Outlet Mass Density Inner Stream"
134        Inner.Properties.Outlet.rho     =       PP.LiquidDensity(OutletInner.T,OutletInner.P,OutletInner.z);
135
136"Average Viscosity Inner Stream"
137        Inner.Properties.Average.Mu     =       PP.LiquidViscosity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
138
139"Average        Conductivity Inner Stream"
140        Inner.Properties.Average.K              =       PP.LiquidThermalConductivity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
141
142"Viscosity Inner Stream at wall temperature"
143        Inner.Properties.Wall.Mu                =       PP.LiquidViscosity(Inner.Properties.Wall.Twall,Inner.Properties.Average.P,InletInner.z);
144
145        else
146
147"Average Heat Capacity InnerStream"
148        Inner.Properties.Average.Cp     =       PP.VapourCp(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
149
150"Average Mass Density Inner Stream"
151        Inner.Properties.Average.rho    =       PP.VapourDensity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
152
153"Inlet Mass Density Inner Stream"
154        Inner.Properties.Inlet.rho              =       PP.VapourDensity(InletInner.T,InletInner.P,InletInner.z);
155       
156"Outlet Mass Density Inner Stream"
157        Inner.Properties.Outlet.rho     =       PP.VapourDensity(OutletInner.T,OutletInner.P,OutletInner.z);
158
159"Average Viscosity Inner Stream"
160        Inner.Properties.Average.Mu     =       PP.VapourViscosity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
161
162"Average Conductivity Inner Stream"
163        Inner.Properties.Average.K              =       PP.VapourThermalConductivity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
164
165"Viscosity Inner Stream at wall temperature"
166        Inner.Properties.Wall.Mu                =       PP.VapourViscosity(Inner.Properties.Wall.Twall,Inner.Properties.Average.P,InletInner.z);
167
168end
169
170if InletOuter.v equal 0
171
172        then
173
174"Average Heat Capacity Outer Stream"
175        Outer.Properties.Average.Cp     =               PP.LiquidCp(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
176
177"Average Mass Density Outer Stream"
178        Outer.Properties.Average.rho =          PP.LiquidDensity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
179
180"Inlet Mass Density Outer Stream"
181        Outer.Properties.Inlet.rho              =               PP.LiquidDensity(InletOuter.T,InletOuter.P,InletOuter.z);
182
183"Outlet Mass Density Outer Stream"
184        Outer.Properties.Outlet.rho     =               PP.LiquidDensity(OutletOuter.T,OutletOuter.P,OutletOuter.z);
185
186"Average Viscosity Outer Stream"
187        Outer.Properties.Average.Mu     =               PP.LiquidViscosity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
188
189"Average Conductivity Outer Stream"
190        Outer.Properties.Average.K      =               PP.LiquidThermalConductivity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);       
191
192"Viscosity Outer Stream at wall temperature"
193        Outer.Properties.Wall.Mu                =               PP.LiquidViscosity(Outer.Properties.Wall.Twall,Outer.Properties.Average.P,InletOuter.z);       
194
195
196        else
197
198"Average Heat Capacity Outer Stream"
199        Outer.Properties.Average.Cp     =               PP.VapourCp(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
200
201"Average Mass Density Outer Stream"
202        Outer.Properties.Average.rho =          PP.VapourDensity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
203
204"Inlet Mass Density Outer Stream"
205        Outer.Properties.Inlet.rho              =               PP.VapourDensity(InletOuter.T,InletOuter.P,InletOuter.z);
206       
207"Outlet Mass Density Outer Stream"
208        Outer.Properties.Outlet.rho     =               PP.VapourDensity(OutletOuter.T,OutletOuter.P,OutletOuter.z);
209
210"Average Viscosity Outer Stream"
211        Outer.Properties.Average.Mu     =               PP.VapourViscosity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
212
213"Average Conductivity Outer Stream"
214        Outer.Properties.Average.K      =               PP.VapourThermalConductivity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);       
215
216"Viscosity Outer Stream at wall temperature"
217        Outer.Properties.Wall.Mu                =               PP.VapourViscosity(Outer.Properties.Wall.Twall,Outer.Properties.Average.P,InletOuter.z);
218
219end
220
221switch HotSide
222       
223        case "outer":
224
225"Energy Balance Outer Stream"
226        Details.Q = InletOuter.F*(InletOuter.h-OutletOuter.h);
227
228"Energy Balance Inner Stream"
229        Details.Q = InletInner.F*(OutletInner.h-InletInner.h);
230
231        when InletInner.T > InletOuter.T switchto "inner";
232
233case "inner":
234
235"Energy Balance Hot Stream"
236        Details.Q = InletInner.F*(InletInner.h-OutletInner.h);
237
238"Energy Balance Cold Stream"
239        Details.Q = InletOuter.F*(OutletOuter.h - InletOuter.h);
240
241        when InletInner.T < InletOuter.T switchto "outer";
242
243end
244
245"Flow Mass Inlet Inner Stream"
246        Inner.Properties.Inlet.Fw       =  sum(M*InletInner.z)*InletInner.F;
247
248"Flow Mass Outlet Inner Stream"
249        Inner.Properties.Outlet.Fw      =  sum(M*OutletInner.z)*OutletInner.F;
250
251"Flow Mass Inlet Outer Stream"
252        Outer.Properties.Inlet.Fw               =  sum(M*InletOuter.z)*InletOuter.F;
253
254"Flow Mass Outlet Outer Stream"
255        Outer.Properties.Outlet.Fw      =  sum(M*OutletOuter.z)*OutletOuter.F;
256
257"Molar Balance Outer Stream"
258        OutletOuter.F = InletOuter.F;
259       
260"Molar Balance Inner Stream"
261        OutletInner.F = InletInner.F;
262
263"Outer Stream Molar Fraction Constraint"
264        OutletOuter.z=InletOuter.z;
265       
266"InnerStream Molar Fraction Constraint"
267        OutletInner.z=InletInner.z;
268
269"Exchange Surface Area for one segment of pipe"
270        Details.A=Pi*DoInner*(2*Lpipe);
271
272switch innerFlowRegime
273       
274        case "laminar":
275       
276"Inner Side Friction Factor for Pressure Drop - laminar Flow"
277        Inner.PressureDrop.fi*Inner.PressureDrop.Re = 16;
278       
279        when Inner.PressureDrop.Re > 2300 switchto "transition";
280
281        case "transition":
282       
283"using Turbulent Flow - to be implemented"
284        (Inner.PressureDrop.fi-0.0035)*(Inner.PressureDrop.Re^0.42) = 0.264;
285
286        when Inner.PressureDrop.Re < 2300 switchto "laminar";
287        when Inner.PressureDrop.Re > 10000 switchto "turbulent";
288
289        case "turbulent":
290
291"Inner Side Friction Factor - Turbulent Flow"
292        (Inner.PressureDrop.fi-0.0035)*(Inner.PressureDrop.Re^0.42) = 0.264;
293
294        when Inner.PressureDrop.Re < 10000 switchto "transition";
295       
296end     
297
298switch outerFlowRegime
299       
300        case "laminar":
301       
302"Outer Side Friction Factor - laminar Flow"
303        Outer.PressureDrop.fi*Outer.PressureDrop.Re = 16;
304       
305        when Outer.PressureDrop.Re > 2300 switchto "transition";
306
307        case "transition":
308       
309"using Turbulent Flow - Transition Flow must be implemented"
310        (Outer.PressureDrop.fi-0.0035)*(Outer.PressureDrop.Re^0.42) = 0.264;
311
312        when Outer.PressureDrop.Re < 2300 switchto "laminar";
313        when Outer.PressureDrop.Re > 10000 switchto "turbulent";
314
315        case "turbulent":
316
317"Outer Side Friction Factor - Turbulent Flow"
318        (Outer.PressureDrop.fi-0.0035)*(Outer.PressureDrop.Re^0.42) = 0.264;
319
320        when Outer.PressureDrop.Re < 10000 switchto "transition";
321       
322end
323
324switch innerFlowRegime
325       
326        case "laminar":
327       
328"Inner Side Friction Factor for Heat Transfer - laminar Flow"
329        Inner.HeatTransfer.fi   = 1/(0.79*ln(Inner.HeatTransfer.Re)-1.64)^2;
330       
331switch InnerLaminarCorrelation
332       
333        case "Hausen":
334
335"Nusselt Number"
336        Inner.HeatTransfer.Nu = 3.665 + ((0.19*((DiInner/Lpipe)*Inner.HeatTransfer.Re*Inner.HeatTransfer.PR)^0.8)/(1+0.117*((DiInner/Lpipe)*Inner.HeatTransfer.Re*Inner.HeatTransfer.PR)^0.467));
337       
338        case "Schlunder":
339
340"Nusselt Number"
341        Inner.HeatTransfer.Nu = (49.027896+4.173281*Inner.HeatTransfer.Re*Inner.HeatTransfer.PR*(DiInner/Lpipe))^(1/3);
342
343end
344       
345        when Inner.HeatTransfer.Re > 2300 switchto "transition";
346       
347        case "transition":
348       
349"Inner Side Friction Factor for Heat Transfer - transition Flow"
350        Inner.HeatTransfer.fi   = 1/(0.79*ln(Inner.HeatTransfer.Re)-1.64)^2;
351       
352switch InnerTransitionCorrelation
353       
354        case "Gnielinski":
355       
356"Nusselt Number"
357        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;
358
359        case "Hausen":
360
361"Nusselt Number"
362        Inner.HeatTransfer.Nu =0.116*(Inner.HeatTransfer.Re^(0.667)-125)*Inner.HeatTransfer.PR^(0.333)*(1+(DiInner/Lpipe)^0.667);
363       
364end
365
366        when Inner.HeatTransfer.Re < 2300 switchto "laminar";
367        when Inner.HeatTransfer.Re > 10000 switchto "turbulent";
368
369        case "turbulent":
370
371switch InnerTurbulentCorrelation
372       
373        case "Petukhov":
374       
375"Inner Side Friction Factor for Heat Transfer - turbulent Flow"
376        Inner.HeatTransfer.fi   = 1/(1.82*log(Inner.HeatTransfer.Re)-1.64)^2;
377
378"Nusselt Number"
379        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;
380       
381        case "SiederTate":
382
383"Nusselt Number"
384        Inner.HeatTransfer.Nu = 0.027*(Inner.HeatTransfer.PR)^(1/3)*(Inner.HeatTransfer.Re)^(4/5);
385
386"Inner Side Friction Factor for Heat Transfer - turbulent Flow"
387        Inner.HeatTransfer.fi   = 1/(1.82*log(Inner.HeatTransfer.Re)-1.64)^2;
388       
389end
390       
391        when Inner.HeatTransfer.Re < 10000 switchto "transition";
392       
393end
394
395switch outerFlowRegime
396       
397        case "laminar":
398       
399"Outer Side Friction Factor for Heat Transfer - laminar Flow"
400        Outer.HeatTransfer.fi   = 1/(0.79*ln(Outer.HeatTransfer.Re)-1.64)^2;
401       
402switch OuterLaminarCorrelation
403       
404        case "Hausen":
405
406"Nusselt Number"
407        Outer.HeatTransfer.Nu = 3.665 + ((0.19*((Outer.HeatTransfer.Dh/Lpipe)*Outer.HeatTransfer.Re*Outer.HeatTransfer.PR)^0.8)/(1+0.117*((Outer.HeatTransfer.Dh/Lpipe)*Outer.HeatTransfer.Re*Outer.HeatTransfer.PR)^0.467));
408       
409        case "Schlunder":
410
411"Nusselt Number"
412        Outer.HeatTransfer.Nu = (49.027896+4.173281*Outer.HeatTransfer.Re*Outer.HeatTransfer.PR*(Outer.HeatTransfer.Dh/Lpipe))^(1/3);
413
414end
415       
416        when Outer.HeatTransfer.Re > 2300 switchto "transition";
417       
418        case "transition":
419       
420switch OuterTransitionCorrelation
421       
422        case "Gnielinski":
423
424"Outer Side Friction Factor for Heat Transfer - transition Flow"
425        Outer.HeatTransfer.fi   = 1/(0.79*ln(Outer.HeatTransfer.Re)-1.64)^2;
426
427"Nusselt Number"
428        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;
429
430        case "Hausen":
431
432"Nusselt Number"
433        Outer.HeatTransfer.Nu = 0.116*(Outer.HeatTransfer.Re^(0.667)-125)*Outer.HeatTransfer.PR^(0.333)*(1+(Outer.HeatTransfer.Dh/Lpipe)^0.667);
434
435
436"Outer Side Friction Factor for Heat Transfer - transition Flow"
437        Outer.HeatTransfer.fi   = 1/(0.79*ln(Outer.HeatTransfer.Re)-1.64)^2;
438       
439end
440       
441        when Outer.HeatTransfer.Re < 2300 switchto "laminar";
442        when Outer.HeatTransfer.Re > 10000 switchto "turbulent";
443       
444        case "turbulent":
445       
446switch OuterTurbulentCorrelation
447       
448        case "Petukhov":
449
450"Outer Side Friction Factor for Heat Transfer - turbulent Flow"
451        Outer.HeatTransfer.fi   = 1/(1.82*log(Outer.HeatTransfer.Re)-1.64)^2;
452       
453"Nusselt Number"
454        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;
455       
456        case "SiederTate":
457
458"Nusselt Number"
459        Outer.HeatTransfer.Nu = 0.027*(Outer.HeatTransfer.PR)^(1/3)*(Outer.HeatTransfer.Re)^(4/5);
460
461"Outer Side Friction Factor for Heat Transfer - turbulent Flow"
462        Outer.HeatTransfer.fi   = 1/(1.82*log(Outer.HeatTransfer.Re)-1.64)^2;
463       
464end
465
466        when Outer.HeatTransfer.Re < 10000 switchto "transition";
467
468end
469
470"Inner Pipe Film Coefficient"
471        Inner.HeatTransfer.hcoeff = (Inner.HeatTransfer.Nu*Inner.Properties.Average.K/DiInner)*Inner.HeatTransfer.Phi;
472
473"Outer Pipe Film Coefficient"
474        Outer.HeatTransfer.hcoeff= (Outer.HeatTransfer.Nu*Outer.Properties.Average.K/Outer.HeatTransfer.Dh)*Outer.HeatTransfer.Phi;
475
476"Total Pressure Drop Outer Stream"
477        Outer.PressureDrop.Pdrop  = Outer.PressureDrop.Pd_fric+Outer.PressureDrop.Pd_ret;
478
479"Total Pressure Drop Inner Stream"
480        Inner.PressureDrop.Pdrop  = Inner.PressureDrop.Pd_fric+Inner.PressureDrop.Pd_ret;
481       
482"Pressure Drop Outer Stream"
483        OutletOuter.P  = InletOuter.P - Outer.PressureDrop.Pdrop;
484
485"Pressure Drop Inner Stream"
486        OutletInner.P  = InletInner.P - Inner.PressureDrop.Pdrop;
487       
488"Outer Pipe Pressure Drop for friction"
489        Outer.PressureDrop.Pd_fric = (2*Outer.PressureDrop.fi*(2*Lpipe)*Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean^2)/(Outer.PressureDrop.Dh*Outer.HeatTransfer.Phi);
490       
491"Inner Pipe Pressure Drop for friction"
492        Inner.PressureDrop.Pd_fric = (2*Inner.PressureDrop.fi*(2*Lpipe)*Inner.Properties.Average.rho*Inner.HeatTransfer.Vmean^2)/(DiInner*Inner.HeatTransfer.Phi);
493
494"Outer Pipe Pressure Drop due to return"
495        Outer.PressureDrop.Pd_ret = 1.5*Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean^2;
496
497"Inner Pipe Pressure Drop due to return"
498        Inner.PressureDrop.Pd_ret = 1.5*Inner.Properties.Average.rho*Inner.HeatTransfer.Vmean^2;
499
500"Outer Pipe Phi correction"
501        Outer.HeatTransfer.Phi = (Outer.Properties.Average.Mu/Outer.Properties.Wall.Mu)^0.14;
502       
503"Inner Pipe Phi correction"
504        Inner.HeatTransfer.Phi  = (Inner.Properties.Average.Mu/Inner.Properties.Wall.Mu)^0.14;
505
506"Outer Pipe Prandtl Number"
507        Outer.HeatTransfer.PR = ((Outer.Properties.Average.Cp/Outer.Properties.Average.Mw)*Outer.Properties.Average.Mu)/Outer.Properties.Average.K;
508
509"Inner Pipe Prandtl Number"
510        Inner.HeatTransfer.PR = ((Inner.Properties.Average.Cp/Inner.Properties.Average.Mw)*Inner.Properties.Average.Mu)/Inner.Properties.Average.K;
511
512"Outer Pipe Reynolds Number for Heat Transfer"
513        Outer.HeatTransfer.Re = (Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean*Outer.HeatTransfer.Dh)/Outer.Properties.Average.Mu;
514
515"Outer Pipe Reynolds Number for Pressure Drop"
516        Outer.PressureDrop.Re = (Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean*Outer.PressureDrop.Dh)/Outer.Properties.Average.Mu;
517
518"Inner Pipe Reynolds Number for Heat Transfer"
519        Inner.HeatTransfer.Re = (Inner.Properties.Average.rho*Inner.HeatTransfer.Vmean*Inner.HeatTransfer.Dh)/Inner.Properties.Average.Mu;
520
521"Inner Pipe Reynolds Number for Pressure Drop"
522        Inner.PressureDrop.Re = Inner.HeatTransfer.Re;
523
524"Outer Pipe Velocity"
525        Outer.HeatTransfer.Vmean*(Outer.HeatTransfer.As*Outer.Properties.Average.rho)  = Outer.Properties.Inlet.Fw;
526
527"Inner Pipe Velocity"
528        Inner.HeatTransfer.Vmean*(Inner.HeatTransfer.As*Inner.Properties.Average.rho)  = Inner.Properties.Inlet.Fw;
529
530"Overall Heat Transfer Coefficient Clean"
531        Details.Uc*((DoInner/(Inner.HeatTransfer.hcoeff*DiInner) )+(DoInner*ln(DoInner/DiInner)/(2*Kwall))+(1/(Outer.HeatTransfer.hcoeff)))=1;
532
533"Overall Heat Transfer Coefficient Dirty"
534        Details.Ud*(Rfi*(DoInner/DiInner) +  Rfo + (DoInner/(Inner.HeatTransfer.hcoeff*DiInner) )+(DoInner*ln(DoInner/DiInner)/(2*Kwall))+(1/(Outer.HeatTransfer.hcoeff)))=1;
535
536end
537
538Model Hairpin_NTU as Hairpin_Basic
539
540ATTRIBUTES
541
542        Icon = "icon/hairpin";
543        Pallete = true;
544        Brief  = "Hairpin Heat Exchanger - NTU Method";
545        Info  =
546        "to be documented.";
547
548PARAMETERS
549
550FlowDirection   as Switcher     (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent");
551       
552VARIABLES
553
554Method as NTU_Basic     (Brief="NTU Method of Calculation", Symbol=" ");
555
556EQUATIONS
557
558"Number of Units Transference"
559        Method.NTU*Method.Cmin = Details.Ud*Pi*DoInner*(2*Lpipe);
560       
561"Minimum Heat Capacity"
562        Method.Cmin  = min([Method.Ch,Method.Cc]);
563
564"Maximum Heat Capacity"
565        Method.Cmax  = max([Method.Ch,Method.Cc]);
566
567"Thermal Capacity Ratio"
568        Method.Cr    = Method.Cmin/Method.Cmax;
569
570"Effectiveness Correction"
571        Method.Eft1 = 1;
572
573if Method.Cr equal 0
574       
575        then   
576"Effectiveness"
577        Method.Eft = 1-exp(-Method.NTU);
578       
579        else
580
581switch  FlowDirection
582
583        case "cocurrent":
584       
585"Effectiveness in Cocurrent Flow"
586        Method.Eft = (1-exp(-Method.NTU*(1+Method.Cr)))/(1+Method.Cr);
587
588        case "counter":
589
590if Method.Eft >= 1
591       
592        then
593       
594"Effectiveness in Counter Flow"
595        Method.Eft = 1;
596       
597        else
598       
599"Effectiveness in Counter Flow"
600        Method.NTU*(Method.Cr-1.00001) = ln(abs((Method.Eft-1.00001))) - ln(abs((Method.Cr*Method.Eft-1.00001)));
601end
602
603end
604
605end
606
607switch HotSide
608       
609        case "outer":
610
611"Duty"
612        Details.Q       = Method.Eft*Method.Cmin*(InletOuter.T-InletInner.T);
613
614"Hot Stream Heat Capacity"
615        Method.Ch  = InletOuter.F*Outer.Properties.Average.Cp;
616       
617"Cold Stream Heat Capacity"
618        Method.Cc = InletInner.F*Inner.Properties.Average.Cp;
619
620        when InletInner.T > InletOuter.T switchto "inner";
621       
622        case "inner":
623
624"Duty"
625        Details.Q       = Method.Eft*Method.Cmin*(InletInner.T-InletOuter.T);
626
627"Cold Stream Heat Capacity"
628        Method.Cc = InletOuter.F*Outer.Properties.Average.Cp;
629       
630"Hot Stream Heat Capacity"
631        Method.Ch = InletInner.F*Inner.Properties.Average.Cp;
632       
633        when InletInner.T < InletOuter.T switchto "outer";
634       
635end
636
637end
638
639Model Hairpin_LMTD as Hairpin_Basic
640       
641ATTRIBUTES
642
643        Icon = "icon/hairpin";
644        Pallete = true;
645        Brief  = "Hairpin Heat Exchanger - LMTD Method";
646        Info  =
647        "to be documented.";
648
649PARAMETERS
650
651FlowDirection   as Switcher     (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent");
652       
653VARIABLES
654
655Method as LMTD_Basic    (Brief="LMTD Method of Calculation", Symbol=" ");
656
657EQUATIONS
658
659"Exchange Surface Area"
660        Details.Q = Details.Ud*Pi*DoInner*(2*Lpipe)*Method.LMTD;
661       
662"LMTD Correction Factor - True counter ou cocurrent flow"
663        Method.Fc = 1;
664
665switch HotSide
666       
667        case "outer":
668       
669switch FlowDirection
670
671        case "cocurrent":
672       
673"Temperature Difference at Inlet - Cocurrent Flow"
674        Method.DT0 = InletOuter.T - InletInner.T;
675
676"Temperature Difference at Outlet - Cocurrent Flow"
677        Method.DTL = OutletOuter.T - OutletInner.T;
678
679        case "counter":
680       
681"Temperature Difference at Inlet - Counter Flow"
682        Method.DT0 = InletOuter.T - OutletInner.T;
683
684"Temperature Difference at Outlet - Counter Flow"
685        Method.DTL = OutletOuter.T - InletInner.T;
686       
687
688end
689
690        when InletInner.T > InletOuter.T switchto "inner";
691       
692        case "inner":
693
694switch FlowDirection
695
696        case "cocurrent":
697       
698"Temperature Difference at Inlet - Cocurrent Flow"
699        Method.DT0 = InletInner.T - InletOuter.T;
700
701"Temperature Difference at Outlet - Cocurrent Flow"
702        Method.DTL = OutletInner.T - OutletOuter.T;
703       
704        case "counter":
705       
706"Temperature Difference at Inlet - Counter Flow"
707        Method.DT0 = InletInner.T - OutletOuter.T;
708
709"Temperature Difference at Outlet - Counter Flow"
710        Method.DTL = OutletInner.T - InletOuter.T;
711       
712end
713
714        when InletInner.T < InletOuter.T switchto "outer";
715
716end
717
718end
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