blockMerkel

Model for thermal performance of Merkel cooling tower
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Extends from Buildings.Obsolete.BaseClasses.ObsoleteModel (Icon for classes that are obsolete and will be removed in later versions), Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).

Information

Model for the thermal peformance of the Merkel cooling tower.

For the documentation, see Buildings.Obsolete.Fluid.HeatExchangers.CoolingTowers.Merkel.

Parameters

TypeNameDefaultDescription
Buildings.Obsolete.Fluid.HeatExchangers.CoolingTowers.Data.UAMerkelUACor
Modelica.Units.SI.HeatFlowRateQ_flow_nominal-m_flow_nominal*cpWat_nominal*(TWatIn_nominal - TWatOut_nominal)Nominal heat transfer, (negative)
Modelica.Units.SI.ThermalConductanceUA_nominalNTU_nominal*CMin_flow_nominal*Buildings.Utilities.Psychrometrics.Constants.cpAir/cpEqu_nominalThermal conductance at nominal flow, used to compute heat capacity
Realeps_nominalQ_flow_nominal/((TAirInWB_nominal - TWatIn_nominal)*CMin_flow_nominal)Nominal heat transfer effectiveness
RealNTU_nominalBuildings.Fluid.HeatExchangers.BaseClasses.ntu_epsilonZ(eps = min(1, max(0, eps_nominal)), Z = Z_nominal, flowRegime = Integer(Buildings.Fluid.Types.HeatExchangerConfiguration.CounterFlow))Nominal number of transfer units
Nominal condition
Modelica.Units.SI.MassFlowRatem_flow_nominalNominal mass flow rate of water
RealratWatAir_nominalWater-to-air mass flow rate ratio at design condition
Fan
Modelica.Units.SI.MassFlowRatemAir_flow_nominalm_flow_nominal/ratWatAir_nominalNominal mass flow rate of air
RealyMinMinimum control signal until fan is switched off (used for smoothing between forced and free convection regime)
Heat transfer
Modelica.Units.SI.TemperatureTAirInWB_nominalNominal outdoor (air inlet) wetbulb temperature
Modelica.Units.SI.TemperatureTWatIn_nominalNominal water inlet temperature
Modelica.Units.SI.TemperatureTWatOut_nominalNominal water outlet temperature
RealfraFreConFraction of tower capacity in free convection regime

Connectors

TypeNameDefaultDescription
Modelica.Blocks.Interfaces.RealInputyFan control signal
Modelica.Blocks.Interfaces.RealInputm_flowWater mass flow rate
Modelica.Blocks.Interfaces.RealInputTWatInInlet water temperature
Modelica.Blocks.Interfaces.RealInputTAirEntering air wet bulb temperature
Modelica.Blocks.Interfaces.RealOutputQ_flowHeat removed from water

Components

TypeNameDefaultDescription
Modelica.Units.SI.TemperatureTAirOutOutlet air temperature
Modelica.Units.SI.MassFlowRatemAir_flowAir mass flow rate
Modelica.Units.SI.MassFractionFRWatRatio actual over design water mass flow ratio
Modelica.Units.SI.MassFractionFRAirRatio actual over design air mass flow ratio
RealepsHeat exchanger effectiveness
Modelica.Units.SI.SpecificHeatCapacitycpWatHeat capacity of water
Modelica.Units.SI.ThermalConductanceCAir_flowHeat capacity flow rate of air
Modelica.Units.SI.ThermalConductanceCWat_flowHeat capacity flow rate of water
Modelica.Units.SI.ThermalConductanceCMin_flowMinimum heat capacity flow rate
Modelica.Units.SI.HeatFlowRateQMax_flowMaximum heat flow rate into air
Modelica.Units.SI.ThermalConductanceUAeThermal conductance for equivalent fluid
Modelica.Units.SI.ThermalConductanceUAThermal conductance

Contents

NameDescription
MediumMedium in the component
AirprotectedPackage of medium air

Revisions

  • April 27, 2026, by Michael Wetter:
    Moved to Obsolete package due to new cooling tower implementation.
    This is for issue 4567.
  • April 17, 2025, by Michael Wetter:
    Corrected computation of nominal UA value, which also needs to include the correction for cpEqu_nominal.
    This is for #4189.
  • January 20, 2020, by Michael Wetter:
    First implementation during refactoring of Buildings.Obsolete.Fluid.HeatExchangers.CoolingTowers.Merkel.