modelIndirectEvaporativeHex

Indirect evaporative heat exchanger

Extends from IDEAS.Fluid.Interfaces.PartialFourPortInterface.

Parameters

TypeNameDefaultDescription
Realeps_adia_onHeat exchanger efficiency when adiabatic heat exchange is on, used when not use_eNTU
Realeps_adia_offHeat exchanger efficiency when adiabatic heat exchange is off, used when not use_eNTU
Booleanuse_eNTUtrueUse NTU method for efficiency calculation
Modelica.Units.SI.Timetau60Thermal time constant of the heat exchanger
RealUA_adia_onUA value when using evaporative cooling, used when use_eNTU = true
RealUA_adia_offUA value when not using evaporative cooling, used when use_eNTU = true
Modelica.Units.SI.MassFlowRatem_flow_small1E-4*abs(volTop.m_flow_nominal)Small mass flow rate for regularization of zero flow
BooleansimplifiedMassBalancetrueUse simplified evaporation model to determine outlet humidity of dumped air stream when evaporative cooling is on
BooleanprescribeTBotfalse=True, for validation. Need this option to avoid warnings.
Dynamics › Equations
Modelica.Fluid.Types.DynamicsenergyDynamicsModelica.Fluid.Types.Dynamics.DynamicFreeInitialFormulation of energy balance
Modelica.Fluid.Types.DynamicsmassDynamicsenergyDynamicsFormulation of mass balance
Dynamics
RealmSenFac1Factor for scaling the sensible thermal mass of the volume
Initialization › Medium 1
Medium1.AbsolutePressurep1_startMedium1.p_defaultStart value of pressure
Medium1.TemperatureT1_startMedium1.T_defaultStart value of temperature
Medium1.MassFraction[Medium1.nX]X1_startMedium1.X_defaultStart value of mass fractions m_i/m
Medium1.ExtraProperty[Medium1.nC]C1_startfill(0, Medium1.nC)Start value of trace substances
Medium1.ExtraProperty[Medium1.nC]C1_nominalfill(1E-2, Medium1.nC)Nominal value of trace substances. (Set to typical order of magnitude.)
Initialization › Medium 2
Medium2.AbsolutePressurep2_startMedium2.p_defaultStart value of pressure
Medium2.TemperatureT2_startMedium2.T_defaultStart value of temperature
Medium2.MassFraction[Medium2.nX]X2_startMedium2.X_defaultStart value of mass fractions m_i/m
Medium2.ExtraProperty[Medium2.nC]C2_startfill(0, Medium2.nC)Start value of trace substances
Medium2.ExtraProperty[Medium2.nC]C2_nominalfill(1E-2, Medium2.nC)Nominal value of trace substances. (Set to typical order of magnitude.)

Components

TypeNameDefaultDescription
Modelica.Units.SI.PowerQ
Modelica.Units.SI.EnergyEvolTop.U + volBot.U
Modelica.Blocks.Interfaces.BooleanInputadiabaticOnActivate adiabatic cooling
IDEAS.Fluid.MixingVolumes.MixingVolumeMoistAirvolBot
IDEAS.Fluid.MixingVolumes.MixingVolumeMoistAirvolTopTop heat exchanger volume
Modelica.Blocks.Interfaces.RealOutputTOutBotBottom outlet temperature
Modelica.Blocks.Sources.RealExpressionmFloAdiBotRealexpression for setting condensation mass flow rate
RealXw_in_botXi_bot_in[1]Water mass fraction of bottom stream

Contents

NameDescription
TWetBul_TDryBulXiProtectedprotectedModel for accessing protected variable

Revisions

  • May 22, 2022, by Filip Jorissen:
    Added access to protected variable XiSat. See #1254
  • April 7, 2020, by Filip Jorissen:
    Replaced thermal resistor by thermal conductor to avoid division. See #1129.
  • October 1, 2019, by Filip Jorissen:
    Revised computation of C_star to avoid division by zero for balanced flow.
  • May 15, 2018, by Filip Jorissen:
    Changes for setting unique initial conditions.
  • October 11, 2016, by Filip Jorissen:
    Added first implementation.