Buildings.Experimental.DistrictHeatingCooling.SubStations

Heating and cooling substations

Information

This package contains component and system models for district heating and cooling substations.

Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).

Package Content

Name	Description
Cooling	Cooling substation
Heating	Heating substation
VaporCompression	Package with substations that have a vapor compression engine for heating or cooling
Validation	Package with models for validation
BaseClasses	Package with base classes for substations

Buildings.Experimental.DistrictHeatingCooling.SubStations.Cooling

Cooling substation

Buildings.Experimental.DistrictHeatingCooling.SubStations.Cooling

Information

Substation that adds a prescribed heat flow rate to the water that flows through it. The substation has a built-in pump that draws as much water as needed to maintain the temperature difference dTHex.

Extends from Buildings.Experimental.DistrictHeatingCooling.SubStations.BaseClasses.HeatingOrCooling (Base class for heating or cooling substation).

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
HeatFlowRate	Q_flow_nominal	Q_flow_nominal(max=0)	Nominal heat flow rate added to medium (Q_flow_nominal <= 0) [W]
Nominal condition
MassFlowRate	m_flow_nominal	-Q_flow_nominal/cp_default/d...	Nominal mass flow rate [kg/s]
Design parameter
Pressure	dp_nominal	30000	Pressure difference at nominal flow rate [Pa]
TemperatureDifference	dTHex	4	Temperature difference over the heat exchanger (positive) [K]
Advanced
MassFlowRate	m_flow_small	1E-4*abs(m_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Boolean	show_T	false	= true, if actual temperature at port is computed
Flow resistance
Real	deltaM	0.1	Fraction of nominal flow rate where flow transitions to laminar
Dynamics
Time	tau	30	Time constant at nominal flow (if energyDynamics <> SteadyState) [s]
Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamic...	Type of energy balance: dynamic (3 initialization options) or steady state
Dynamics	massDynamics	energyDynamics	Type of mass balance: dynamic (3 initialization options) or steady state

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	PPum	Electrical power consumed by pump [W]
input RealInput	Q_flow	Heat flow rate extracted from system (Q_flow ≤ 0) [W]

Modelica definition

model Cooling "Cooling substation" extends Buildings.Experimental.DistrictHeatingCooling.SubStations.BaseClasses.HeatingOrCooling ( final m_flow_nominal = -Q_flow_nominal/cp_default/dTHex, mPum_flow(final k=-1/(cp_default*dTHex))); parameter Modelica.SIunits.TemperatureDifference dTHex( min=0.5, displayUnit="K") = 4 "Temperature difference over the heat exchanger (positive)"; parameter Modelica.SIunits.HeatFlowRate Q_flow_nominal(max=0) "Nominal heat flow rate added to medium (Q_flow_nominal <= 0)"; Modelica.Blocks.Interfaces.RealInput Q_flow( max=0, final unit="W") "Heat flow rate extracted from system (Q_flow ≤ 0)"; equation connect(Q_flow, mPum_flow.u); connect(Q_flow, hex.u); end Cooling;

Buildings.Experimental.DistrictHeatingCooling.SubStations.Heating

Heating substation

Buildings.Experimental.DistrictHeatingCooling.SubStations.Heating

Information

Substation that removes a prescribed heat flow rate from the water that flows through it. The substation has a built-in pump that draws as much water as needed to maintain the temperature difference dTHex.

Extends from Buildings.Experimental.DistrictHeatingCooling.SubStations.BaseClasses.HeatingOrCooling (Base class for heating or cooling substation).

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
HeatFlowRate	Q_flow_nominal	Q_flow_nominal(min=0)	Nominal heat flow rate added to medium (Q_flow_nominal > 0) [W]
Nominal condition
MassFlowRate	m_flow_nominal	-Q_flow_nominal/cp_default/d...	Nominal mass flow rate [kg/s]
Design parameter
Pressure	dp_nominal	30000	Pressure difference at nominal flow rate [Pa]
TemperatureDifference	dTHex	-4	Temperature difference over the heat exchanger (negative) [K]
Advanced
MassFlowRate	m_flow_small	1E-4*abs(m_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Boolean	show_T	false	= true, if actual temperature at port is computed
Flow resistance
Real	deltaM	0.1	Fraction of nominal flow rate where flow transitions to laminar
Dynamics
Time	tau	30	Time constant at nominal flow (if energyDynamics <> SteadyState) [s]
Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamic...	Type of energy balance: dynamic (3 initialization options) or steady state
Dynamics	massDynamics	energyDynamics	Type of mass balance: dynamic (3 initialization options) or steady state

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	PPum	Electrical power consumed by pump [W]
input RealInput	Q_flow	Heat flow rate extracted from system (Q_flow >= 0) [W]

Modelica definition

model Heating "Heating substation" extends Buildings.Experimental.DistrictHeatingCooling.SubStations.BaseClasses.HeatingOrCooling ( final m_flow_nominal = -Q_flow_nominal/cp_default/dTHex, mPum_flow(final k=-1/(cp_default*dTHex))); parameter Modelica.SIunits.TemperatureDifference dTHex( max=-0.5, displayUnit="K") = -4 "Temperature difference over the heat exchanger (negative)"; parameter Modelica.SIunits.HeatFlowRate Q_flow_nominal( min=0) "Nominal heat flow rate added to medium (Q_flow_nominal > 0)"; Modelica.Blocks.Interfaces.RealInput Q_flow( min=0, final unit="W") "Heat flow rate extracted from system (Q_flow >= 0)"; equation connect(Q_flow, mPum_flow.u); connect(Q_flow, hex.u); end Heating;