JARA2i.CaseStudies.batchReactor.PhysicalModel

Models used to describe the batch reactor physical model

Information

Models used to describe the batch reactor physical model

Package Content

Name Description

batchReacLiqAtoP Batch reactor physical model

chReacAtoP Liquid-phase chemical reaction A -> P [1]: A, [2]: agua, [3]: P

sourceLiqCntrl Liquid source

sourceOfTemp Source of temperature

thermalResist Thermal resistor

Name	Description
batchReacLiqAtoP	Batch reactor physical model
chReacAtoP	Liquid-phase chemical reaction A -> P [1]: A, [2]: agua, [3]: P
sourceLiqCntrl	Liquid source
sourceOfTemp	Source of temperature
thermalResist	Thermal resistor

JARA2i.CaseStudies.batchReactor.PhysicalModel.batchReacLiqAtoP

Batch reactor physical model

JARA2i.CaseStudies.batchReactor.PhysicalModel.batchReacLiqAtoP

Information

Batch reactor model

In a batch reactor having a volume V, an exothermic reaction from A to P is carried out in the liquid phase.
The reaction velocity is r_A = kC_A, where k depends on the temperature in the following form: k = k₀₁exp(-k₀₂/T), expressed in units of second to minus one. The reactor contains a heat exchanger with a surface A and it can be operated in the following two ways:

Using steam with a heat transfer coefficient h_Ts at a T_s temperature as heating system.
Using cooling water with a heat transfer coefficient h_Tw at a T_w temperature as refrigerator.

The batch reactor model has been extracted from (Froment, G. F. and K. B. Bischoff 1979).
The model is composed of a CV containig the liquid stored in the reactor, a TP modeling the reaction inside the reactor, a pump model and the model of the heat exchanger.
The heat exchanger model is composed of a temperature source and a resistor.

The input of liquid water is placed at the boiler bottom, and the vapor output valve is placed at the top. The output valve has the following constitutive equation: F^m = (F⁰)*sqrt(p(p-p₀)), where p₀ is the valve output pressure. The water contained in the boiler is continually heated. Two control volumes are considered:

A control volume containing the liquid water stored in the boiler.

A gaseous control volume containing the vapor. <\ul>

The vapor volume is equal to the difference between the boiler-recipient inner volume and the water volume. The boiling is a transport phenomena represented by a model connecting both control volumes. The heat-flow into the boiler, the pressure at the valve output and the water pump are modeled using JARA2i source models.

References

Froment, G. F. and K. B. Bischoff (1979): Chemical Reactor Analysis and Design. John Wiley & Sons, New York, USA.

Parameters

Type Name Default Description

Integer nComp 3 Component number of the liqid mixture

Integer numChR 1 Number of irreversible chemical reactions

Boolean Ejs true

Boolean Sysquake false

Real CpCoefMInitial[nComp, 7] [4.5E3, 0, 0, 0, 0, 0, 0; 4.... [J/(Kg*K)]

Real massEnthalpyRefInitial[nComp] {167E4,0,0} Specific (per mass) enthalpy at reference temperature [J/Kg]

Real tempRefInitial 300 Reference temperature [K]

Real molecWeightInitial[nComp] {0.1,0.018,0.1} Molecular weight [Kg/mol]

Real densityInitial[nComp] {1E3,1E3,1E3} Components density [Kg/m3]

Real vesselVinitial 5 Initial reactor volume [m3]

Real vesselSinitial 3 Initial reactor section [m2]

Real stoichCoefInitial[numChR, nComp] [-1, 0, 1] Stoich coeffs.

Real kCoefInitial[2] {4E6,-7.9E3} Reaction velocity coeffs. [{s-1,K}]

Real heatExchAreaInitial 3.3 Exchanger area [m2]

Real hTSteamInitial 1360 Heat-transfer coeff. of the vapor [W/(m2.K)]

Real hTWaterInitial 1180 Heat-transfer coeff. of the water [W/(m2.K)]

Real tempSteam 393 Vapor temperature [K]

Real tempWater 288 Water temperature [K]

Real pmax 1.05*3*vesselVinitial*liq.li...

Real pcodo pmax/1.05 Source parameter

Real pmin 1 Source parameter

Real peps 0.2 Source parameter

Real massLinitial[:] {0,1,0} Initial condition [M]

Real tempLinitial 300 Initial condition [T]

Type	Name	Default	Description
Integer	nComp	3	Component number of the liqid mixture
Integer	numChR	1	Number of irreversible chemical reactions
Boolean	Ejs	true
Boolean	Sysquake	false
Real	CpCoefMInitial[nComp, 7]	[4.5E3, 0, 0, 0, 0, 0, 0; 4....	[J/(Kg*K)]
Real	massEnthalpyRefInitial[nComp]	{167E4,0,0}	Specific (per mass) enthalpy at reference temperature [J/Kg]
Real	tempRefInitial	300	Reference temperature [K]
Real	molecWeightInitial[nComp]	{0.1,0.018,0.1}	Molecular weight [Kg/mol]
Real	densityInitial[nComp]	{1E3,1E3,1E3}	Components density [Kg/m3]
Real	vesselVinitial	5	Initial reactor volume [m3]
Real	vesselSinitial	3	Initial reactor section [m2]
Real	stoichCoefInitial[numChR, nComp]	[-1, 0, 1]	Stoich coeffs.
Real	kCoefInitial[2]	{4E6,-7.9E3}	Reaction velocity coeffs. [{s-1,K}]
Real	heatExchAreaInitial	3.3	Exchanger area [m2]
Real	hTSteamInitial	1360	Heat-transfer coeff. of the vapor [W/(m2.K)]
Real	hTWaterInitial	1180	Heat-transfer coeff. of the water [W/(m2.K)]
Real	tempSteam	393	Vapor temperature [K]
Real	tempWater	288	Water temperature [K]
Real	pmax	1.053vesselVinitial*liq.li...
Real	pcodo	pmax/1.05	Source parameter
Real	pmin	1	Source parameter
Real	peps	0.2	Source parameter
Real	massLinitial[:]	{0,1,0}	Initial condition [M]
Real	tempLinitial	300	Initial condition [T]

Modelica definition

model batchReacLiqAtoP "Batch reactor physical model" 
// [1]: A, [2]: agua, [3]: P 
  
   parameter Integer nComp =    3 "Component number of the liqid mixture";
   parameter Integer numChR =   1 "Number of irreversible chemical reactions";
  
   // Interactivity
   inner parameter Boolean Ejs =      true;
   inner parameter Boolean Sysquake = false;
  
   parameter Real CpCoefMInitial[ nComp,7]( unit="J/(Kg*K)") = [ 4.5E3, 0, 0, 0, 0, 0, 0;
                                                          4.2E3, 0, 0, 0, 0, 0, 0;
                                                          4.5E3, 0, 0, 0, 0, 0, 0];
  
   parameter Real massEnthalpyRefInitial[nComp](  unit="J/Kg") = {167E4, 0, 0} 
    "Specific (per mass) enthalpy at reference temperature";
   parameter Real tempRefInitial(                 unit="K") =    300 
    "Reference temperature";
  
   parameter Real molecWeightInitial[nComp]( unit="Kg/mol") =  {0.1, 0.018, 0.1} 
    "Molecular weight";
   parameter Real densityInitial[nComp](     unit="Kg/m3") =   {1E3, 1E3, 1E3} 
    "Components density";
  
   parameter Real vesselVinitial(  unit="m3") = 5 "Initial reactor volume";
   parameter Real vesselSinitial(  unit="m2") = 3 "Initial reactor section";
  
   parameter Real stoichCoefInitial[ numChR,nComp] =     [-1, 0, 1] 
    "Stoich coeffs.";
   parameter Real kCoefInitial[ 2](          unit="{s-1,K}") =   { 4E6, -7.9E3} 
    "Reaction velocity coeffs.";
  
   parameter Real heatExchAreaInitial(   unit="m2") =       3.3 
    "Exchanger area";
   parameter Real hTSteamInitial(        unit="W/(m2.K)") = 1360 
    "Heat-transfer coeff. of the vapor";
   parameter Real hTWaterInitial(        unit="W/(m2.K)") = 1180 
    "Heat-transfer coeff. of the water";
   parameter Real tempSteam(      unit="K") =        393 "Vapor temperature";
   parameter Real tempWater(      unit="K") =        288 "Water temperature";
  
   parameter Real pmax =      1.05*3*vesselVinitial*liq.liquid.g*
                              max(densityInitial[1],max(densityInitial[2],densityInitial[3])) /
                              (0.5*vesselSinitial);
   parameter Real pcodo =     pmax / 1.05 "Source parameter";
   parameter Real pmin =         1 "Source parameter";
   parameter Real peps =         0.2 "Source parameter";
  
   parameter Real massLinitial[ :](    unit="M") =  { 0, 1, 0} 
    "Initial condition";
   parameter Real tempLinitial(        unit="T") =  300 "Initial condition";
  
   JARA2i.liq.liquidCp6PrefVB liq(   nComp=nComp,CpCoefMInitial=CpCoefMInitial,
                                   vesselVolumeInitial=vesselVinitial,
      densityInitial =                                                               densityInitial,
                                   sectionInitial=vesselSinitial,
      massEnthalpyRefInitial =                                                          massEnthalpyRefInitial,
                                   tempRefInitial=tempRefInitial,
                                   massLinitial=massLinitial,tempLinitial=tempLinitial);
  
   chReacAtoP chRAtoP(       nComp=nComp,numChR=numChR,stoichCoefInitial=stoichCoefInitial,
      kCoefInitial =                                                                                    kCoefInitial,
                             molecWeightInitial=molecWeightInitial,
      densityInitial =                                                            densityInitial);
  
   JARA2i.liq.sourceVolLiqFB liqSource(  nComp=nComp,densityInitial=densityInitial,
      CpCoefMInitial =                                                                          CpCoefMInitial,
                                       pmax=pmax,pcodo=pcodo,pmin=pmin,peps=peps,
                                       massEnthalpyRefInitial=massEnthalpyRefInitial,
      tempRefInitial =                                                                              tempRefInitial);
  
   thermalResist resistTherm(   nCompI=nComp,heatExchAreaInitial=heatExchAreaInitial,
                                hTSteamInitial=hTSteamInitial, hTWaterInitial=hTWaterInitial);
  
   sourceOfTemp fluidTemp(      tempHeatInitial=tempSteam,tempCoolInitial=tempWater);
  
   sourceLiqCntrl sourceLiqCtrl( nComp=nComp);
  
equation 
   // Liquid flow
   connect(   liqSource.inMass,   liq.inMassBot);
   connect(   liq.inMassBot,  chRAtoP.inMass);
   connect(   liq.inHeat,  resistTherm.inHeat);
   connect(   fluidTemp.inHeat,  resistTherm.outHeat);
   connect(   liqSource.setPointSignal,  sourceLiqCtrl.setPointSignal);
  
   // Chemical reaction
  
   // Heat flow
  
   // Control signal
end batchReacLiqAtoP;

JARA2i.CaseStudies.batchReactor.PhysicalModel.chReacAtoP

Liquid-phase chemical reaction A -> P [1]: A, [2]: agua, [3]: P

JARA2i.CaseStudies.batchReactor.PhysicalModel.chReacAtoP

Information

Liquid phase chemical reaction

Class modeling the chemical reaction A ==> P. [1]: A, [2]: agua, [3]: P. This class inherits from chReac.chReacLiqB. The interactive variables of the model are shown in Table 1.

Table 1. Interactive variables.

stoichCoefInitial[numChR,nComp]	Stoichometric coefficients of the chemical reactions. Sign criterium: Reactives are negative. Products are positive.
density[nComp]	Density of the pure components.
molecWeigth[nComp]	Molecular weight of the components.
kCoef[2]	Rate of reaction coefficients.
calcConversion	1: conversion calculation.

References

Froment, G. F. and K. B. Bischoff (1979): Chemical Reactor Analysis and Design. John Wiley & Sons, New York, USA.

Parameters

Type Name Default Description

Integer nComp 1 Number of components

Boolean Ejs false Global parameter - Runtime interactivity

Boolean Sysquake false Global parameter - Batch interactivity

Integer numChR 1 Number of chemical reactions

Real stoichCoefInitial[numChR, nComp] Stoichometric coefficients of the chemical reactions. Sign criterium: Reactives are negative. Products are positive.

Real densityInitial[nComp] Density of the pure components [M.L-3]

Real molecWeightInitial[nComp] Molecular weigth of the components [M.mol-1]

Real calcConversionInitial 0

Real kCoefInitial[2] Rate of reaction coefs [{t-1,T}]

Real eps 1E-8 Small constant to avoid by-zero division

Type	Name	Default	Description
Integer	nComp	1	Number of components
Boolean	Ejs	false	Global parameter - Runtime interactivity
Boolean	Sysquake	false	Global parameter - Batch interactivity
Integer	numChR	1	Number of chemical reactions
Real	stoichCoefInitial[numChR, nComp]		Stoichometric coefficients of the chemical reactions. Sign criterium: Reactives are negative. Products are positive.
Real	densityInitial[nComp]		Density of the pure components [M.L-3]
Real	molecWeightInitial[nComp]		Molecular weigth of the components [M.mol-1]
Real	calcConversionInitial	0
Real	kCoefInitial[2]		Rate of reaction coefs [{t-1,T}]
Real	eps	1E-8	Small constant to avoid by-zero division

Connectors

Type Name Description

cutLiquidR inMass Connector for the liquid flow

Type	Name	Description
cutLiquidR	inMass	Connector for the liquid flow

Modelica definition

model chReacAtoP 
  "Liquid-phase chemical reaction A -> P  [1]: A, [2]: agua, [3]: P " 
// Liquid-phase chemical reaction A -> P 
//  [1]: A, [2]: agua, [3]: P  
  
   extends chReac.chReacLiqB;
  
   Real conversion(           unit="") "Fractional conversion";
  
   Real calcConversion(        start=calcConversionInitial) 
    "1: conversion calculation";
   parameter Real calcConversionInitial = 0;
  
   Real kCoef[2](  unit="{t-1,T}", start=kCoefInitial, fixed=true) 
    "Rate of reaction coefs";
  
   parameter Real kCoefInitial[ 2](  unit="{t-1,T}") "Rate of reaction coefs";
  
   parameter Real eps(        unit="") =  1E-8 
    "Small constant to avoid by-zero division";
  
protected 
   Real kReactionRate(      unit="t-1") "Coeff. rate of reaction vs temp.";
   Real concMolL[  nComp](  unit="mol.L-3") "Molar concentration";
   Real molL[  nComp](      unit="mol") "Number of mols";
   Real massL1Initial(      start = 1, fixed=true) "Mass of A at time = time0";
  
equation 
  if (Ejs) then
   // Interactive parameters
   der(kCoef) = {0,0};
    
   // Interactive variable
   der(calcConversion) = 0;
  end if;
  if (Sysquake) then
   // Interactive parameters
   kCoef =  kCoefInitial;
    
   // Interactive variable
   //calcConversion = calcConversionInitial;
  end if;
   // Number of moles of the components
   for i in 1:nComp loop
      inMass.massL[i] = molecWeight[i] * molL[i];
   end for;
  
   // Arrhenius equation
   kReactionRate = kCoef[1] * exp( kCoef[2] / ( inMass.tempL + eps));
  
   // Molar concentration of the components
   concMolL = molL / ( fluidV + eps);
  
   // Conversion 
   when calcConversion > 0.5 then
      massL1Initial = inMass.massL[1];
   end when;
  
   conversion = if calcConversion < 0.5 then 
                     0 else 
                     ( massL1Initial - inMass.massL[1])  / massL1Initial;
  
   // Rate of reaction 
   reactionRate[1] = kReactionRate * concMolL[1]^ (-stoichCoef[1,1]);
end chReacAtoP;

JARA2i.CaseStudies.batchReactor.PhysicalModel.sourceLiqCntrl

Liquid source

JARA2i.CaseStudies.batchReactor.PhysicalModel.sourceLiqCntrl

Information

Liquid source

Class modeling the input liquid source. [1]: A, [2]: agua, [3]: P. This class inherits from interf.sourceVolLiqSignalI. The interactive variables of the model are shown in Table 1.

Table 1. Interactive variables.

flowVSP	Setpoint of the volumetric flow.
tempSP	Setpoint of the flow temperature.
fractVSP[nComp]	Volumetric fraction of the components.

Parameters

Type Name Default Description

Integer nComp 1 Number of components

Real flowVSPInitial 0 Setpoint of the volumetric flow

Real tempSPInitial 297 Setpoint of the flow temperature

Real fractVSPInitial[nComp] {0.1,0.9,0} Volumetric fraction of the components

Boolean Ejs false Global parameter - Runtime interactivity

Boolean Sysquake false Global parameter - Batch interactivity

Type	Name	Default	Description
Integer	nComp	1	Number of components
Real	flowVSPInitial	0	Setpoint of the volumetric flow
Real	tempSPInitial	297	Setpoint of the flow temperature
Real	fractVSPInitial[nComp]	{0.1,0.9,0}	Volumetric fraction of the components
Boolean	Ejs	false	Global parameter - Runtime interactivity
Boolean	Sysquake	false	Global parameter - Batch interactivity

Connectors

Type Name Description

cutEmitter setPointSignal Set-point of the total volumetric flow, component volume fraction and temperature

Type	Name	Description
cutEmitter	setPointSignal	Set-point of the total volumetric flow, component volume fraction and temperature

Modelica definition

model sourceLiqCntrl "Liquid source" 
  
   extends interf.sourceVolLiqSignalI(nComp=nComp);
   parameter Real flowVSPInitial = 0 "Setpoint of the volumetric flow";
   parameter Real tempSPInitial = 297 "Setpoint of the flow temperature";
   parameter Real fractVSPInitial[nComp] = {0.1, 0.9, 0} 
    "Volumetric fraction of the components";
   Real flowVSP(          unit="L3.t-1", start=flowVSPInitial) 
    "Setpoint of the volumetric flow";
   Real tempSP(           unit="T",      start=tempSPInitial) 
    "Setpoint of the flow temperature";
   Real fractVSP[nComp](  unit="",       start=fractVSPInitial) 
    "Volumetric fraction of the components";
   outer parameter Boolean Ejs = false 
    "Global parameter - Runtime interactivity";
   outer parameter Boolean Sysquake = false 
    "Global parameter - Batch interactivity";
equation 
   totalVolFSP    = flowVSP;
   volFractSP     = fractVSP;
   tempFSP        = tempSP;
  
   if (Ejs) then
   // Interactive variables
   der(flowVSP) = 0;
   der(tempSP)  = 0;
   der(fractVSP) = zeros(size(fractVSP,1));
   end if;
  
   if (Sysquake) then
    
   end if;
  
end sourceLiqCntrl;

JARA2i.CaseStudies.batchReactor.PhysicalModel.sourceOfTemp

Source of temperature

JARA2i.CaseStudies.batchReactor.PhysicalModel.sourceOfTemp

Information

Source of temperature

Class modeling the temperature source. This class inherits from heat.sourceTempB. The interactive variables of the model are shown in Table 1.

Table 1. Interactive variables.

tempHeat	Heater temperature.
tempCool	Chiller temperature.
isHeater	1: isHeater.
isChiller	1: isChiller.

Parameters

Type Name Default Description

Integer nComp 1 Number of components

Real isHeaterInitial 0 1: heater

Real isChillerInitial 0 1: chiller

Real tempHeatInitial 300 Heater temperature [T]

Real tempCoolInitial 300 Chiller temperature [T]

Real tempOff 300 Off temperature [T]

Boolean Ejs false Global parameter - Runtime interactivity

Boolean Sysquake false Global parameter - Batch interactivity

Type	Name	Default	Description
Integer	nComp	1	Number of components
Real	isHeaterInitial	0	1: heater
Real	isChillerInitial	0	1: chiller
Real	tempHeatInitial	300	Heater temperature [T]
Real	tempCoolInitial	300	Chiller temperature [T]
Real	tempOff	300	Off temperature [T]
Boolean	Ejs	false	Global parameter - Runtime interactivity
Boolean	Sysquake	false	Global parameter - Batch interactivity

Connectors

Type Name Description

cutHeatMC inHeat Connector for the heat conduction.

Type	Name	Description
cutHeatMC	inHeat	Connector for the heat conduction.

Modelica definition

model sourceOfTemp "Source of temperature" 
  
   extends heat.sourceTempB;
  
   parameter Real isHeaterInitial = 0 "1: heater";
   parameter Real isChillerInitial = 0 "1: chiller";
  
   Real isHeater(       start=isHeaterInitial) "1: heater";
   Real isChiller(      start=isChillerInitial) "1: chiller";
  
   parameter Real tempHeatInitial(  unit="T") = 300 "Heater temperature";
   parameter Real tempCoolInitial(  unit="T") = 300 "Chiller temperature";
   parameter Real tempOff(          unit="T") = 300 "Off temperature";
  
   Real tempHeat(  unit="T", start=tempHeatInitial, fixed=true) 
    "Heater temperature";
   Real tempCool(  unit="T", start=tempCoolInitial, fixed=true) 
    "Chiller temperature";
  
   Real consumHeater(     unit="", start=0, fixed=true) 
    "Heater:  normalized amount of fluid";
   Real consumChiller(    unit="", start=0, fixed=true) 
    "Chiller: normalized amount of fluid";
   outer parameter Boolean Ejs = false 
    "Global parameter - Runtime interactivity";
   outer parameter Boolean Sysquake = false 
    "Global parameter - Batch interactivity";
equation 
   // Interactive parameters
  if (Ejs) then
   der(tempHeat)  = 0;
   der(tempCool)  = 0;
   der(isHeater)  = 0;
   der(isChiller) = 0;
  end if;
  
  if (Sysquake) then
    
  end if;
  
   // Source temperature
   sourceTemp = if isHeater > 0.5 then 
                     tempHeat else 
                     if isChiller > 0.5 then 
                          tempCool else 
                          tempOff;
  
   // Normalized amount of fluid
   der(consumHeater)  = if isHeater  > 0.5 then 1 else 0;
   der(consumChiller) = if isChiller > 0.5 then 1 else 0;
end sourceOfTemp;

JARA2i.CaseStudies.batchReactor.PhysicalModel.thermalResist

Thermal resistor

JARA2i.CaseStudies.batchReactor.PhysicalModel.thermalResist

Information

Thermal resistor

Class modeling the thermal resistor. This class inherits from heat.resistThermB. The interactive variables of the model are shown in Table 1.

Table 1. Interactive variables.

hTSteam	Heat transfer coefficient of the steam.
hTWater	Heat transfer coefficient of the water.
isHeater	1: isHeater.
isChiller	1: isChiller.
heatExchArea	Heat-exchanger area.

Parameters

Type Name Default Description

Integer nCompI 1 Number of components of inHeat

Integer nCompO 1 Number of components of outHeat

Boolean Ejs false Global parameter - Runtime interactivity

Boolean Sysquake false Global parameter - Batch interactivity

Real eps 1.E-10 Small parameter to avoid by-zero division [T.M-1.L-2.t3]

Real RthOff 1E20 Off thermal resistance [T.M-1.L-2.t3]

Real heatExchAreaInitial 3.3 Exchanger area [L2]

Real hTSteamInitial Heat transfer coefficient

Real hTWaterInitial Heat transfer coefficient

Real isHeaterInitial 0 1: heater

Real isChillerInitial 0 1: chiller

Type	Name	Default	Description
Integer	nCompI	1	Number of components of inHeat
Integer	nCompO	1	Number of components of outHeat
Boolean	Ejs	false	Global parameter - Runtime interactivity
Boolean	Sysquake	false	Global parameter - Batch interactivity
Real	eps	1.E-10	Small parameter to avoid by-zero division [T.M-1.L-2.t3]
Real	RthOff	1E20	Off thermal resistance [T.M-1.L-2.t3]
Real	heatExchAreaInitial	3.3	Exchanger area [L2]
Real	hTSteamInitial		Heat transfer coefficient
Real	hTWaterInitial		Heat transfer coefficient
Real	isHeaterInitial	0	1: heater
Real	isChillerInitial	0	1: chiller

Connectors

Type Name Description

cutHeatMR inHeat Heat flow

cutHeatMR outHeat Heat flow

Type	Name	Description
cutHeatMR	inHeat	Heat flow
cutHeatMR	outHeat	Heat flow

Modelica definition

model thermalResist "Thermal resistor" 
  
   extends heat.resistThermB;
  
   parameter Real RthOff(   unit="T.M-1.L-2.t3") = 1E20 
    "Off thermal resistance";
  
   Real RthHeater(    unit="T.M-1.L-2.t3") "Thermal resistance of the heater";
   Real RthCooler(    unit="T.M-1.L-2.t3") "Thermal resistance of the chiller";
  
   parameter Real heatExchAreaInitial(  unit="L2") = 3.3 "Exchanger area";
   parameter Real hTSteamInitial "Heat transfer coefficient";
   parameter Real hTWaterInitial "Heat transfer coefficient";
   parameter Real isHeaterInitial = 0 "1: heater";
   parameter Real isChillerInitial = 0 "1: chiller";
  
   // Interactive variables
  
   Real isHeater(    start=isHeaterInitial) "1: heater";
   Real isChiller(   start=isChillerInitial) "1: chiller";
  
   Real hTSteam(  start=hTSteamInitial, fixed=true);
   Real hTWater(  start=hTWaterInitial, fixed=true);
  
   Real heatExchArea( start=heatExchAreaInitial, fixed=true, unit="L2") 
    "Exchanger area";
  
equation 
   // Interactive variables
  if (Ejs) then
   der(hTSteam)   = 0;
   der(hTWater)   = 0;
   der(isHeater)  = 0;
   der(isChiller) = 0;
   der(heatExchArea) = 0;
  end if;
  
  if (Sysquake) then
   hTSteam   = hTSteamInitial;
   hTWater   = hTWaterInitial;
   heatExchArea = heatExchAreaInitial;
  end if;
  
   // Thermal resistance
   Rtherm = if isHeater > 0.5 then 
                 RthHeater else 
                 if isChiller > 0.5 then 
                      RthCooler else 
                      RthOff;
  
   RthHeater     = 1/(heatExchArea*hTSteam+1e-10);
  
   RthCooler     = 1/(heatExchArea*hTWater+1e-10);
end thermalResist;

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