source: trunk/eml/heat_exchangers/Hairpin.mso @ 1002

Last change on this file since 1002 was 528, checked in by gerson bicca, 15 years ago

updated hairpin model

File size: 25.4 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",Hidden=true);
35       
36        HotSide                         as Switcher             (Brief="Flag for Fluid Alocation ",Valid=["outer","inner"],Default="outer",Hidden=true);
37        innerFlowRegime         as Switcher     (Brief="Inner Flow Regime ",Valid=["laminar","transition","turbulent"],Default="laminar",Hidden=true);
38        outerFlowRegime         as Switcher     (Brief="Outer Flow Regime ",Valid=["laminar","transition","turbulent"],Default="laminar",Hidden=true);
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        CalculationApproach                             as Switcher             (Brief="Options for convergence Calculations ",Valid=["Simplified","Full"],Default="Full");
49        Qestimated                                                              as power                                (Brief="Estimated Duty", Default=70, Lower=1e-6, Upper=1e10);
50       
51        Pi                              as constant             (Brief="Pi Number",Default=3.14159265, Symbol = "\pi",Hidden=true);
52        DoInner         as length                       (Brief="Outside Diameter of Inner Pipe",Lower=1e-6);
53        DiInner as length                       (Brief="Inside Diameter of Inner Pipe",Lower=1e-10);
54        DiOuter as length                       (Brief="Inside Diameter of Outer pipe",Lower=1e-10);
55        Lpipe           as length                       (Brief="Effective Tube Length of one segment of Pipe",Lower=0.1, Symbol = "L_{pipe}");
56        Kwall           as conductivity         (Brief="Tube Wall Material Thermal Conductivity",Default=1.0, Symbol = "K_{wall}");
57        Rfi                     as positive                     (Brief="Inside Fouling Resistance",Unit='m^2*K/kW',Default=1e-6,Lower=0);
58        Rfo                     as positive                     (Brief="Outside Fouling Resistance",Unit='m^2*K/kW',Default=1e-6,Lower=0);
59
60VARIABLES
61
62in  InletInner          as stream               (Brief="Inlet Inner Stream", PosX=1, PosY=0.7, Symbol="_{inInner}");   
63in  InletOuter          as stream               (Brief="Inlet Outer Stream", PosX=0.8, PosY=0, Symbol="_{inOuter}");
64out OutletInner         as streamPH     (Brief="Outlet Inner Stream", PosX=1, PosY=0.3, Symbol="_{outInner}");
65out OutletOuter         as streamPH     (Brief="Outlet Outer Stream", PosX=0.8, PosY=1, Symbol="_{outOuter}");
66
67        Details         as Details_Main         (Brief="Some Details in the Heat Exchanger", Symbol=" ");
68        Inner                   as Main_DoublePipe      (Brief="Inner Side of the Heat Exchanger", Symbol="_{Inner}");
69        Outer                   as Main_DoublePipe      (Brief="Outer Side of the Heat Exchanger", Symbol="_{Outer}");
70
71SET
72
73#"Component Molecular Weight"
74        M  = PP.MolecularWeight();
75       
76#"Pi Number"
77        Pi      = 3.14159265;
78       
79#"Inner Pipe Cross Sectional Area for Flow"
80        Inner.HeatTransfer.As=Pi*DiInner*DiInner/4;
81       
82#"Outer Pipe Cross Sectional Area for Flow"
83        Outer.HeatTransfer.As=Pi*(DiOuter*DiOuter - DoInner*DoInner)/4;
84       
85#"Inner Pipe Hydraulic Diameter for Heat Transfer"
86        Inner.HeatTransfer.Dh=DiInner;
87       
88#"Outer Pipe Hydraulic Diameter for Heat Transfer"
89        Outer.HeatTransfer.Dh=(DiOuter*DiOuter-DoInner*DoInner)/DoInner;
90
91#"Inner Pipe Hydraulic Diameter for Pressure Drop"
92        Inner.PressureDrop.Dh=DiInner;
93       
94#"Outer Pipe Hydraulic Diameter for Pressure Drop"
95        Outer.PressureDrop.Dh=DiOuter-DoInner;
96
97EQUATIONS
98
99"Outer  Stream Average Temperature"
100        Outer.Properties.Average.T = 0.5*InletOuter.T + 0.5*OutletOuter.T;
101
102"Inner Stream Average Temperature"
103        Inner.Properties.Average.T = 0.5*InletInner.T + 0.5*OutletInner.T;
104       
105"Outer Stream Average Pressure"
106        Outer.Properties.Average.P = 0.5*InletOuter.P+0.5*OutletOuter.P;
107       
108"Inner Stream Average Pressure"
109        Inner.Properties.Average.P = 0.5*InletInner.P+0.5*OutletInner.P;
110
111"Inner Stream Wall Temperature"
112        Inner.Properties.Wall.Twall =   0.5*Outer.Properties.Average.T + 0.5*Inner.Properties.Average.T;
113
114"Outer Stream Wall Temperature"
115        Outer.Properties.Wall.Twall =   0.5*Outer.Properties.Average.T + 0.5*Inner.Properties.Average.T;
116
117"Outer Stream Average Molecular Weight"
118        Outer.Properties.Average.Mw = sum(M*InletOuter.z);
119
120"Inner Stream Average Molecular Weight"
121        Inner.Properties.Average.Mw = sum(M*InletInner.z);
122
123if InletInner.v equal 0
124       
125        then   
126
127"Average Heat Capacity Inner Stream"
128        Inner.Properties.Average.Cp             =       PP.LiquidCp(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
129
130"Average Mass Density Inner Stream"
131        Inner.Properties.Average.rho    =       PP.LiquidDensity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
132
133"Inlet Mass Density Inner Stream"
134        Inner.Properties.Inlet.rho              =       PP.LiquidDensity(InletInner.T,InletInner.P,InletInner.z);
135
136"Outlet Mass Density Inner Stream"
137        Inner.Properties.Outlet.rho     =       PP.LiquidDensity(OutletInner.T,OutletInner.P,OutletInner.z);
138
139"Average Viscosity Inner Stream"
140        Inner.Properties.Average.Mu     =       PP.LiquidViscosity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
141
142"Average        Conductivity Inner Stream"
143        Inner.Properties.Average.K              =       PP.LiquidThermalConductivity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
144
145"Viscosity Inner Stream at wall temperature"
146        Inner.Properties.Wall.Mu                =       PP.LiquidViscosity(Inner.Properties.Wall.Twall,Inner.Properties.Average.P,InletInner.z);
147
148        else
149
150"Average Heat Capacity InnerStream"
151        Inner.Properties.Average.Cp     =       PP.VapourCp(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
152
153"Average Mass Density Inner Stream"
154        Inner.Properties.Average.rho    =       PP.VapourDensity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
155
156"Inlet Mass Density Inner Stream"
157        Inner.Properties.Inlet.rho              =       PP.VapourDensity(InletInner.T,InletInner.P,InletInner.z);
158       
159"Outlet Mass Density Inner Stream"
160        Inner.Properties.Outlet.rho     =       PP.VapourDensity(OutletInner.T,OutletInner.P,OutletInner.z);
161
162"Average Viscosity Inner Stream"
163        Inner.Properties.Average.Mu     =       PP.VapourViscosity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
164
165"Average Conductivity Inner Stream"
166        Inner.Properties.Average.K              =       PP.VapourThermalConductivity(Inner.Properties.Average.T,Inner.Properties.Average.P,InletInner.z);
167
168"Viscosity Inner Stream at wall temperature"
169        Inner.Properties.Wall.Mu                =       PP.VapourViscosity(Inner.Properties.Wall.Twall,Inner.Properties.Average.P,InletInner.z);
170
171end
172
173if InletOuter.v equal 0
174
175        then
176
177"Average Heat Capacity Outer Stream"
178        Outer.Properties.Average.Cp     =               PP.LiquidCp(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
179
180"Average Mass Density Outer Stream"
181        Outer.Properties.Average.rho =          PP.LiquidDensity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
182
183"Inlet Mass Density Outer Stream"
184        Outer.Properties.Inlet.rho              =               PP.LiquidDensity(InletOuter.T,InletOuter.P,InletOuter.z);
185
186"Outlet Mass Density Outer Stream"
187        Outer.Properties.Outlet.rho     =               PP.LiquidDensity(OutletOuter.T,OutletOuter.P,OutletOuter.z);
188
189"Average Viscosity Outer Stream"
190        Outer.Properties.Average.Mu     =               PP.LiquidViscosity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
191
192"Average Conductivity Outer Stream"
193        Outer.Properties.Average.K      =               PP.LiquidThermalConductivity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);       
194
195"Viscosity Outer Stream at wall temperature"
196        Outer.Properties.Wall.Mu                =               PP.LiquidViscosity(Outer.Properties.Wall.Twall,Outer.Properties.Average.P,InletOuter.z);       
197
198
199        else
200
201"Average Heat Capacity Outer Stream"
202        Outer.Properties.Average.Cp     =               PP.VapourCp(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
203
204"Average Mass Density Outer Stream"
205        Outer.Properties.Average.rho =          PP.VapourDensity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
206
207"Inlet Mass Density Outer Stream"
208        Outer.Properties.Inlet.rho              =               PP.VapourDensity(InletOuter.T,InletOuter.P,InletOuter.z);
209       
210"Outlet Mass Density Outer Stream"
211        Outer.Properties.Outlet.rho     =               PP.VapourDensity(OutletOuter.T,OutletOuter.P,OutletOuter.z);
212
213"Average Viscosity Outer Stream"
214        Outer.Properties.Average.Mu     =               PP.VapourViscosity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);
215
216"Average Conductivity Outer Stream"
217        Outer.Properties.Average.K      =               PP.VapourThermalConductivity(Outer.Properties.Average.T,Outer.Properties.Average.P,InletOuter.z);       
218
219"Viscosity Outer Stream at wall temperature"
220        Outer.Properties.Wall.Mu                =               PP.VapourViscosity(Outer.Properties.Wall.Twall,Outer.Properties.Average.P,InletOuter.z);
221
222end
223
224switch HotSide
225       
226        case "outer":
227
228"Energy Balance Outer Stream"
229        Details.Q = InletOuter.F*(InletOuter.h-OutletOuter.h);
230
231"Energy Balance Inner Stream"
232        Details.Q = InletInner.F*(OutletInner.h-InletInner.h);
233
234        when InletInner.T > InletOuter.T switchto "inner";
235
236case "inner":
237
238"Energy Balance Hot Stream"
239        Details.Q = InletInner.F*(InletInner.h-OutletInner.h);
240
241"Energy Balance Cold Stream"
242        Details.Q = InletOuter.F*(OutletOuter.h - InletOuter.h);
243
244        when InletInner.T < InletOuter.T switchto "outer";
245
246end
247
248"Flow Mass Inlet Inner Stream"
249        Inner.Properties.Inlet.Fw       =  sum(M*InletInner.z)*InletInner.F;
250
251"Flow Mass Outlet Inner Stream"
252        Inner.Properties.Outlet.Fw      =  sum(M*OutletInner.z)*OutletInner.F;
253
254"Flow Mass Inlet Outer Stream"
255        Outer.Properties.Inlet.Fw               =  sum(M*InletOuter.z)*InletOuter.F;
256
257"Flow Mass Outlet Outer Stream"
258        Outer.Properties.Outlet.Fw      =  sum(M*OutletOuter.z)*OutletOuter.F;
259
260"Molar Balance Outer Stream"
261        OutletOuter.F = InletOuter.F;
262       
263"Molar Balance Inner Stream"
264        OutletInner.F = InletInner.F;
265
266"Outer Stream Molar Fraction Constraint"
267        OutletOuter.z=InletOuter.z;
268       
269"InnerStream Molar Fraction Constraint"
270        OutletInner.z=InletInner.z;
271
272"Exchange Surface Area for one segment of pipe"
273        Details.A=Pi*DoInner*(2*Lpipe);
274
275switch innerFlowRegime
276       
277        case "laminar":
278       
279"Inner Side Friction Factor for Pressure Drop - laminar Flow"
280        Inner.PressureDrop.fi*Inner.PressureDrop.Re = 16;
281       
282        when Inner.PressureDrop.Re > 2300 switchto "transition";
283
284        case "transition":
285       
286"using Turbulent Flow - to be implemented"
287        (Inner.PressureDrop.fi-0.0035)*(Inner.PressureDrop.Re^0.42) = 0.264;
288
289        when Inner.PressureDrop.Re < 2300 switchto "laminar";
290        when Inner.PressureDrop.Re > 10000 switchto "turbulent";
291
292        case "turbulent":
293
294"Inner Side Friction Factor - Turbulent Flow"
295        (Inner.PressureDrop.fi-0.0035)*(Inner.PressureDrop.Re^0.42) = 0.264;
296
297        when Inner.PressureDrop.Re < 10000 switchto "transition";
298       
299end     
300
301switch outerFlowRegime
302       
303        case "laminar":
304       
305"Outer Side Friction Factor - laminar Flow"
306        Outer.PressureDrop.fi*Outer.PressureDrop.Re = 16;
307       
308        when Outer.PressureDrop.Re > 2300 switchto "transition";
309
310        case "transition":
311       
312"using Turbulent Flow - Transition Flow must be implemented"
313        (Outer.PressureDrop.fi-0.0035)*(Outer.PressureDrop.Re^0.42) = 0.264;
314
315        when Outer.PressureDrop.Re < 2300 switchto "laminar";
316        when Outer.PressureDrop.Re > 10000 switchto "turbulent";
317
318        case "turbulent":
319
320"Outer Side Friction Factor - Turbulent Flow"
321        (Outer.PressureDrop.fi-0.0035)*(Outer.PressureDrop.Re^0.42) = 0.264;
322
323        when Outer.PressureDrop.Re < 10000 switchto "transition";
324       
325end
326
327switch innerFlowRegime
328       
329        case "laminar":
330       
331"Inner Side Friction Factor for Heat Transfer - laminar Flow"
332        Inner.HeatTransfer.fi   = 1/(0.79*ln(Inner.HeatTransfer.Re)-1.64)^2;
333       
334switch InnerLaminarCorrelation
335       
336        case "Hausen":
337
338"Nusselt Number"
339        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));
340       
341        case "Schlunder":
342
343"Nusselt Number"
344        Inner.HeatTransfer.Nu = (49.027896+4.173281*Inner.HeatTransfer.Re*Inner.HeatTransfer.PR*(DiInner/Lpipe))^(1/3);
345
346end
347       
348        when Inner.HeatTransfer.Re > 2300 switchto "transition";
349       
350        case "transition":
351       
352"Inner Side Friction Factor for Heat Transfer - transition Flow"
353        Inner.HeatTransfer.fi   = 1/(0.79*ln(Inner.HeatTransfer.Re)-1.64)^2;
354       
355switch InnerTransitionCorrelation
356       
357        case "Gnielinski":
358       
359"Nusselt Number"
360        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;
361
362        case "Hausen":
363
364"Nusselt Number"
365        Inner.HeatTransfer.Nu =0.116*(Inner.HeatTransfer.Re^(0.667)-125)*Inner.HeatTransfer.PR^(0.333)*(1+(DiInner/Lpipe)^0.667);
366       
367end
368
369        when Inner.HeatTransfer.Re < 2300 switchto "laminar";
370        when Inner.HeatTransfer.Re > 10000 switchto "turbulent";
371
372        case "turbulent":
373
374switch InnerTurbulentCorrelation
375       
376        case "Petukhov":
377       
378"Inner Side Friction Factor for Heat Transfer - turbulent Flow"
379        Inner.HeatTransfer.fi   = 1/(1.82*log(Inner.HeatTransfer.Re)-1.64)^2;
380
381"Nusselt Number"
382        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;
383       
384        case "SiederTate":
385
386"Nusselt Number"
387        Inner.HeatTransfer.Nu = 0.027*(Inner.HeatTransfer.PR)^(1/3)*(Inner.HeatTransfer.Re)^(4/5);
388
389"Inner Side Friction Factor for Heat Transfer - turbulent Flow"
390        Inner.HeatTransfer.fi   = 1/(1.82*log(Inner.HeatTransfer.Re)-1.64)^2;
391       
392end
393       
394        when Inner.HeatTransfer.Re < 10000 switchto "transition";
395       
396end
397
398switch outerFlowRegime
399       
400        case "laminar":
401       
402"Outer Side Friction Factor for Heat Transfer - laminar Flow"
403        Outer.HeatTransfer.fi   = 1/(0.79*ln(Outer.HeatTransfer.Re)-1.64)^2;
404       
405switch OuterLaminarCorrelation
406       
407        case "Hausen":
408
409"Nusselt Number"
410        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));
411       
412        case "Schlunder":
413
414"Nusselt Number"
415        Outer.HeatTransfer.Nu = (49.027896+4.173281*Outer.HeatTransfer.Re*Outer.HeatTransfer.PR*(Outer.HeatTransfer.Dh/Lpipe))^(1/3);
416
417end
418       
419        when Outer.HeatTransfer.Re > 2300 switchto "transition";
420       
421        case "transition":
422       
423switch OuterTransitionCorrelation
424       
425        case "Gnielinski":
426
427"Outer Side Friction Factor for Heat Transfer - transition Flow"
428        Outer.HeatTransfer.fi   = 1/(0.79*ln(Outer.HeatTransfer.Re)-1.64)^2;
429
430"Nusselt Number"
431        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;
432
433        case "Hausen":
434
435"Nusselt Number"
436        Outer.HeatTransfer.Nu = 0.116*(Outer.HeatTransfer.Re^(0.667)-125)*Outer.HeatTransfer.PR^(0.333)*(1+(Outer.HeatTransfer.Dh/Lpipe)^0.667);
437
438
439"Outer Side Friction Factor for Heat Transfer - transition Flow"
440        Outer.HeatTransfer.fi   = 1/(0.79*ln(Outer.HeatTransfer.Re)-1.64)^2;
441       
442end
443       
444        when Outer.HeatTransfer.Re < 2300 switchto "laminar";
445        when Outer.HeatTransfer.Re > 10000 switchto "turbulent";
446       
447        case "turbulent":
448       
449switch OuterTurbulentCorrelation
450       
451        case "Petukhov":
452
453"Outer Side Friction Factor for Heat Transfer - turbulent Flow"
454        Outer.HeatTransfer.fi   = 1/(1.82*log(Outer.HeatTransfer.Re)-1.64)^2;
455       
456"Nusselt Number"
457        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;
458       
459        case "SiederTate":
460
461"Nusselt Number"
462        Outer.HeatTransfer.Nu = 0.027*(Outer.HeatTransfer.PR)^(1/3)*(Outer.HeatTransfer.Re)^(4/5);
463
464"Outer Side Friction Factor for Heat Transfer - turbulent Flow"
465        Outer.HeatTransfer.fi   = 1/(1.82*log(Outer.HeatTransfer.Re)-1.64)^2;
466       
467end
468
469        when Outer.HeatTransfer.Re < 10000 switchto "transition";
470
471end
472
473"Inner Pipe Film Coefficient"
474        Inner.HeatTransfer.hcoeff = (Inner.HeatTransfer.Nu*Inner.Properties.Average.K/DiInner)*Inner.HeatTransfer.Phi;
475
476"Outer Pipe Film Coefficient"
477        Outer.HeatTransfer.hcoeff= (Outer.HeatTransfer.Nu*Outer.Properties.Average.K/Outer.HeatTransfer.Dh)*Outer.HeatTransfer.Phi;
478
479switch CalculationApproach
480       
481        case "Full":
482
483"Total Pressure Drop Outer Stream"
484        Outer.PressureDrop.Pdrop  = Outer.PressureDrop.Pd_fric+Outer.PressureDrop.Pd_ret;
485
486"Total Pressure Drop Inner Stream"
487        Inner.PressureDrop.Pdrop  = Inner.PressureDrop.Pd_fric+Inner.PressureDrop.Pd_ret;
488       
489"Pressure Drop Outer Stream"
490        OutletOuter.P  = InletOuter.P - Outer.PressureDrop.Pdrop;
491
492"Pressure Drop Inner Stream"
493        OutletInner.P  = InletInner.P - Inner.PressureDrop.Pdrop;
494       
495"Outer Pipe Pressure Drop for friction"
496        Outer.PressureDrop.Pd_fric = (2*Outer.PressureDrop.fi*(2*Lpipe)*Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean^2)/(Outer.PressureDrop.Dh*Outer.HeatTransfer.Phi);
497       
498"Inner Pipe Pressure Drop for friction"
499        Inner.PressureDrop.Pd_fric = (2*Inner.PressureDrop.fi*(2*Lpipe)*Inner.Properties.Average.rho*Inner.HeatTransfer.Vmean^2)/(DiInner*Inner.HeatTransfer.Phi);
500
501"Outer Pipe Pressure Drop due to return"
502        Outer.PressureDrop.Pd_ret = 1.5*Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean^2;
503
504"Inner Pipe Pressure Drop due to return"
505        Inner.PressureDrop.Pd_ret = 1.5*Inner.Properties.Average.rho*Inner.HeatTransfer.Vmean^2;
506
507"Outer Pipe Phi correction"
508        Outer.HeatTransfer.Phi = (Outer.Properties.Average.Mu/Outer.Properties.Wall.Mu)^0.14;
509       
510"Inner Pipe Phi correction"
511        Inner.HeatTransfer.Phi  = (Inner.Properties.Average.Mu/Inner.Properties.Wall.Mu)^0.14;
512
513        case "Simplified":
514
515"Total Pressure Drop Outer Stream"
516        Outer.PressureDrop.Pdrop  = 0*'kPa';
517
518"Total Pressure Drop Inner Stream"
519        Inner.PressureDrop.Pdrop  = 0*'kPa';
520       
521"Pressure Drop Outer Stream"
522        OutletOuter.P  = InletOuter.P;
523
524"Pressure Drop Inner Stream"
525        OutletInner.P  = InletInner.P;
526       
527"Outer Pipe Pressure Drop for friction"
528        Outer.PressureDrop.Pd_fric = 0*'kPa';
529       
530"Inner Pipe Pressure Drop for friction"
531        Inner.PressureDrop.Pd_fric = 0*'kPa';
532
533"Outer Pipe Pressure Drop due to return"
534        Outer.PressureDrop.Pd_ret = 0*'kPa';
535
536"Inner Pipe Pressure Drop due to return"
537        Inner.PressureDrop.Pd_ret = 0*'kPa';
538
539"Outer Pipe Phi correction"
540        Outer.HeatTransfer.Phi = 1;
541       
542"Inner Pipe Phi correction"
543        Inner.HeatTransfer.Phi  = 1;
544
545end
546
547"Outer Pipe Prandtl Number"
548        Outer.HeatTransfer.PR = ((Outer.Properties.Average.Cp/Outer.Properties.Average.Mw)*Outer.Properties.Average.Mu)/Outer.Properties.Average.K;
549
550"Inner Pipe Prandtl Number"
551        Inner.HeatTransfer.PR = ((Inner.Properties.Average.Cp/Inner.Properties.Average.Mw)*Inner.Properties.Average.Mu)/Inner.Properties.Average.K;
552
553"Outer Pipe Reynolds Number for Heat Transfer"
554        Outer.HeatTransfer.Re = (Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean*Outer.HeatTransfer.Dh)/Outer.Properties.Average.Mu;
555
556"Outer Pipe Reynolds Number for Pressure Drop"
557        Outer.PressureDrop.Re = (Outer.Properties.Average.rho*Outer.HeatTransfer.Vmean*Outer.PressureDrop.Dh)/Outer.Properties.Average.Mu;
558
559"Inner Pipe Reynolds Number for Heat Transfer"
560        Inner.HeatTransfer.Re = (Inner.Properties.Average.rho*Inner.HeatTransfer.Vmean*Inner.HeatTransfer.Dh)/Inner.Properties.Average.Mu;
561
562"Inner Pipe Reynolds Number for Pressure Drop"
563        Inner.PressureDrop.Re = Inner.HeatTransfer.Re;
564
565"Outer Pipe Velocity"
566        Outer.HeatTransfer.Vmean*(Outer.HeatTransfer.As*Outer.Properties.Average.rho)  = Outer.Properties.Inlet.Fw;
567
568"Inner Pipe Velocity"
569        Inner.HeatTransfer.Vmean*(Inner.HeatTransfer.As*Inner.Properties.Average.rho)  = Inner.Properties.Inlet.Fw;
570
571"Overall Heat Transfer Coefficient Clean"
572        Details.Uc*((DoInner/(Inner.HeatTransfer.hcoeff*DiInner) )+(DoInner*ln(DoInner/DiInner)/(2*Kwall))+(1/(Outer.HeatTransfer.hcoeff)))=1;
573
574"Overall Heat Transfer Coefficient Dirty"
575        Details.Ud*(Rfi*(DoInner/DiInner) +  Rfo + (DoInner/(Inner.HeatTransfer.hcoeff*DiInner) )+(DoInner*ln(DoInner/DiInner)/(2*Kwall))+(1/(Outer.HeatTransfer.hcoeff)))=1;
576
577end
578
579Model Hairpin_NTU as Hairpin_Basic
580
581ATTRIBUTES
582
583        Icon = "icon/hairpin";
584        Pallete = true;
585        Brief  = "Hairpin Heat Exchanger - NTU Method";
586        Info  =
587        "to be documented.";
588
589PARAMETERS
590
591FlowDirection   as Switcher     (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent");
592Eftestimated            as positive     (Brief="Effectiveness estimate",Default=0.5);
593
594VARIABLES
595
596Method as NTU_Basic     (Brief="NTU Method of Calculation", Symbol=" ");
597
598EQUATIONS
599
600"Effectiveness Correction"
601        Method.Eft1 = 1;
602
603switch CalculationApproach
604
605        case "Full":
606
607"Number of Units Transference"
608        Method.NTU*Method.Cmin = Details.Ud*Pi*DoInner*(2*Lpipe);
609       
610"Minimum Heat Capacity"
611        Method.Cmin  = min([Method.Ch,Method.Cc]);
612
613"Maximum Heat Capacity"
614        Method.Cmax  = max([Method.Ch,Method.Cc]);
615
616"Thermal Capacity Ratio"
617        Method.Cr    = Method.Cmin/Method.Cmax;
618
619if Method.Cr equal 0
620       
621        then   
622"Effectiveness"
623        Method.Eft = 1-exp(-Method.NTU);
624       
625        else
626
627switch  FlowDirection
628
629        case "cocurrent":
630       
631"Effectiveness in Cocurrent Flow"
632        Method.Eft = (1-exp(-Method.NTU*(1+Method.Cr)))/(1+Method.Cr);
633
634        case "counter":
635
636if Method.Eft >= 1
637       
638        then
639       
640"Effectiveness in Counter Flow"
641        Method.Eft = 1;
642       
643        else
644       
645"Effectiveness in Counter Flow"
646        Method.NTU*(Method.Cr-1.00001) = ln(abs((Method.Eft-1.00001))) - ln(abs((Method.Cr*Method.Eft-1.00001)));
647end
648
649end
650
651end
652
653        case "Simplified":
654
655"Number of Units Transference"
656        Method.NTU = 1;
657       
658"Minimum Heat Capacity"
659        Method.Cmin  = min([Method.Ch,Method.Cc]);
660
661"Maximum Heat Capacity"
662        Method.Cmax  = max([Method.Ch,Method.Cc]);
663
664"Thermal Capacity Ratio"
665        Method.Cr    = 1;
666
667"Effectiveness"
668        Method.Eft = Eftestimated;
669
670end
671
672switch HotSide
673       
674        case "outer":
675
676switch CalculationApproach
677
678        case "Full":
679
680"Duty"
681        Details.Q       = Method.Eft*Method.Cmin*(InletOuter.T-InletInner.T);
682
683        case "Simplified":
684
685"Duty"
686        Details.Q       = Qestimated;
687
688end
689
690"Hot Stream Heat Capacity"
691        Method.Ch  = InletOuter.F*Outer.Properties.Average.Cp;
692       
693"Cold Stream Heat Capacity"
694        Method.Cc = InletInner.F*Inner.Properties.Average.Cp;
695
696        when InletInner.T > InletOuter.T switchto "inner";
697       
698        case "inner":
699
700switch CalculationApproach
701
702        case "Full":
703
704"Duty"
705        Details.Q       = Method.Eft*Method.Cmin*(InletInner.T-InletOuter.T);
706
707        case "Simplified":
708
709"Duty"
710        Details.Q       = Qestimated;
711       
712end
713
714"Cold Stream Heat Capacity"
715        Method.Cc = InletOuter.F*Outer.Properties.Average.Cp;
716       
717"Hot Stream Heat Capacity"
718        Method.Ch = InletInner.F*Inner.Properties.Average.Cp;
719       
720        when InletInner.T < InletOuter.T switchto "outer";
721       
722end
723
724end
725
726Model Hairpin_LMTD as Hairpin_Basic
727       
728ATTRIBUTES
729
730        Icon = "icon/hairpin";
731        Pallete = true;
732        Brief  = "Hairpin Heat Exchanger - LMTD Method";
733        Info  =
734        "to be documented.";
735
736PARAMETERS
737
738FlowDirection   as Switcher     (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent");
739       
740VARIABLES
741
742Method as LMTD_Basic    (Brief="LMTD Method of Calculation", Symbol=" ");
743
744EQUATIONS
745
746switch CalculationApproach
747
748        case "Full":
749
750"Duty"
751        Details.Q = Details.Ud*Pi*DoInner*(2*Lpipe)*Method.LMTD;
752
753        case "Simplified":
754
755"Duty  Estimated"
756        Details.Q = Qestimated;
757
758end
759
760"LMTD Correction Factor - True counter ou cocurrent flow"
761        Method.Fc = 1;
762
763switch HotSide
764       
765        case "outer":
766       
767switch FlowDirection
768
769        case "cocurrent":
770       
771"Temperature Difference at Inlet - Cocurrent Flow"
772        Method.DT0 = InletOuter.T - InletInner.T;
773
774"Temperature Difference at Outlet - Cocurrent Flow"
775        Method.DTL = OutletOuter.T - OutletInner.T;
776
777        case "counter":
778       
779"Temperature Difference at Inlet - Counter Flow"
780        Method.DT0 = InletOuter.T - OutletInner.T;
781
782"Temperature Difference at Outlet - Counter Flow"
783        Method.DTL = OutletOuter.T - InletInner.T;
784       
785
786end
787
788        when InletInner.T > InletOuter.T switchto "inner";
789       
790        case "inner":
791
792switch FlowDirection
793
794        case "cocurrent":
795       
796"Temperature Difference at Inlet - Cocurrent Flow"
797        Method.DT0 = InletInner.T - InletOuter.T;
798
799"Temperature Difference at Outlet - Cocurrent Flow"
800        Method.DTL = OutletInner.T - OutletOuter.T;
801       
802        case "counter":
803       
804"Temperature Difference at Inlet - Counter Flow"
805        Method.DT0 = InletInner.T - OutletOuter.T;
806
807"Temperature Difference at Outlet - Counter Flow"
808        Method.DTL = OutletInner.T - InletOuter.T;
809       
810end
811
812        when InletInner.T < InletOuter.T switchto "outer";
813
814end
815
816end
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