modelHeatExchanger

Base subsystem with district heat exchanger

Extends from Buildings.Obsolete.BaseClasses.ObsoleteModel, Buildings.Fluid.Interfaces.PartialFourPortInterface.

Information

This is a model for a district heat exchanger system with a variable speed pump on the secondary side, and a variable speed pump (in case of a passive network) or a two-way modulating valve (in case of an active network) on the primary side.

The system is controlled based on the logic described in Buildings.Obsolete.DHC.ETS.Combined.Controls.HeatExchanger. The pump flow rate is considered proportional to the pump speed under the assumption of a constant flow resistance in both the primary and the secondary loops.

Parameters

TypeNameDefaultDescription
Buildings.DHC.ETS.Types.ConnectionConfigurationconConDistrict connection configuration
Nominal condition
Modelica.Units.SI.PressureDifferencedp1Hex_nominalNominal pressure drop across heat exchanger on district side
Modelica.Units.SI.PressureDifferencedp2Hex_nominalNominal pressure drop across heat exchanger on building side
Modelica.Units.SI.PressureDifferencedpVal1_nominaldp1Hex_nominal/2Nominal pressure drop of primary control valve
Modelica.Units.SI.PressureDifferencedpVal2_nominaldp2Hex_nominal/2Nominal pressure drop of secondary control valve
Modelica.Units.SI.HeatFlowRateQ_flow_nominalNominal heat flow rate (from district to building)
Modelica.Units.SI.TemperatureT_a1_nominalNominal water inlet temperature on district side
Modelica.Units.SI.TemperatureT_b1_nominalNominal water outlet temperature on district side
Modelica.Units.SI.TemperatureT_a2_nominalNominal water inlet temperature on building side
Modelica.Units.SI.TemperatureT_b2_nominalNominal water outlet temperature on building side
Controls
RealspePum1Min0.1Heat exchanger primary pump minimum speed (fractional)
RealspePum2Min0.1Heat exchanger secondary pump minimum speed (fractional)

Components

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Interfaces.RealInput[2]yValIso_actualIsolation valves return position (index 1 for condenser)
Buildings.Controls.OBC.CDL.Interfaces.RealInputuControl signal for secondary side (from supervisory)
Buildings.Controls.OBC.CDL.Interfaces.RealOutputPPumPower drawn by pump motors
Buildings.Obsolete.DHC.ETS.Combined.Controls.HeatExchangerconDistrict heat exchanger loop controller
Buildings.Fluid.HeatExchangers.PlateHeatExchangerEffectivenessNTUhexHeat exchanger
Buildings.DHC.ETS.BaseClasses.Pump_m_flowpum1District heat exchanger primary pump
Buildings.DHC.ETS.BaseClasses.Pump_m_flowpum2Secondary pump
Buildings.Fluid.Sensors.TemperatureTwoPortsenT2WatEntHeat exchanger secondary water entering temperature
Buildings.Fluid.Sensors.TemperatureTwoPortsenT2WatLvgHeat exchanger secondary water leaving temperature
Buildings.Controls.OBC.CDL.Reals.MultiplyByParametergai2Scale to nominal mass flow rate
Buildings.Fluid.Actuators.Valves.TwoWayPressureIndependentval1Heat exchanger primary control valve
Buildings.Controls.OBC.CDL.Reals.MultiplyByParametergai1Scale to nominal mass flow rate
Buildings.Controls.OBC.CDL.Reals.MultiSumtotPPumTotal pump power
Buildings.Fluid.Actuators.Valves.ThreeWayEqualPercentageLinearval2Control valve
Buildings.DHC.ETS.BaseClasses.JunctionsplFlow splitter

Revisions

  • November 14, 2025, by Michael Wetter:
    Moved to Buildings.Obsolete.
    This is for #4354.
  • March 27, 2024, by David Blum:
    Update icon.
    This is for issue #3606.
  • July 14, 2021, by Antoine Gautier:
    Refactored after updating the control logic, changed the primary control valve to pressure-independent.
    This is for issue #2561.
  • July 31, 2020, by Antoine Gautier:
    First implementation.