Buildings.Experimental.DHC.Networks.Steam

Collection of models for distribution networks involving steam

Information

This package contains models for steam heating distribution networks.

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

Package Content

Name Description
Buildings.Experimental.DHC.Networks.Steam.ConnectionCondensatePipe ConnectionCondensatePipe Connection for a steam district heating network featuring the condensate return pipe
Buildings.Experimental.DHC.Networks.Steam.DistributionCondensatePipe DistributionCondensatePipe Model of a steam distribution network using fixed resistance pipe model for condensate returns
Buildings.Experimental.DHC.Networks.Steam.Examples Examples Collection of models that illustrate model use and test models

Buildings.Experimental.DHC.Networks.Steam.ConnectionCondensatePipe Buildings.Experimental.DHC.Networks.Steam.ConnectionCondensatePipe

Connection for a steam district heating network featuring the condensate return pipe

Buildings.Experimental.DHC.Networks.Steam.ConnectionCondensatePipe

Information

This network connection model contains one pipe declaration for the condensate pipe, featuring a fixed hydraulic resistance. This model is intended for steam heating systems that utilize a split-medium approach with two separate medium declarations between liquid and vapor states.

In this model, it is assumed that there are no mass losses in the network connection. Further, heat transfer with the external environment and transport delays are also not included.

Reference

Hinkelman, Kathryn, Saranya Anbarasu, Michael Wetter, Antoine Gautier, and Wangda Zuo. 2022. “A Fast and Accurate Modeling Approach for Water and Steam Thermodynamics with Practical Applications in District Heating System Simulation.” Preprint. February 24. doi:10.13140/RG.2.2.20710.29762.

Extends from Buildings.Experimental.DHC.Networks.BaseClasses.PartialConnection2Pipe2Medium (Partial model for connecting an agent to a two-pipe distribution network with two medium declarations).

Parameters

TypeNameDefaultDescription
replaceable package MediumSupPartialMediumMedium model for supply fluid
replaceable package MediumRetPartialMediumMedium model for return fluid
replaceable model Model_pipDisSupPartialTwoPortInterfaceInterface for inlet pipe for the distribution supply
replaceable model Model_pipDisRetPartialTwoPortInterfaceInterface for outlet pipe for the distribution return
Nominal condition
MassFlowRatemDis_flow_nominal Nominal mass flow rate in the distribution line [kg/s]
MassFlowRatemCon_flow_nominal Nominal mass flow rate in the connection line [kg/s]
PressureDifferencedp_nominal Pressure drop at nominal mass flow rate [Pa]
Assumptions
BooleanallowFlowReversalfalse= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
Equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Type of energy balance: dynamic (3 initialization options) or steady state
Nominal condition
Timetau10Time constant at nominal flow for dynamic energy and momentum balance [s]

Connectors

TypeNameDescription
replaceable model Model_pipDisSupInterface for inlet pipe for the distribution supply
replaceable model Model_pipDisRetInterface for outlet pipe for the distribution return
FluidPort_aport_aDisSupDistribution supply inlet port
FluidPort_bport_bDisSupDistribution supply outlet port
FluidPort_aport_aDisRetDistribution return inlet port
FluidPort_bport_bDisRetDistribution return outlet port
FluidPort_bport_bConConnection supply port
FluidPort_aport_aConConnection return port

Modelica definition

model ConnectionCondensatePipe "Connection for a steam district heating network featuring the condensate return pipe" extends Buildings.Experimental.DHC.Networks.BaseClasses.PartialConnection2Pipe2Medium ( redeclare final model Model_pipDisRet = Buildings.Fluid.FixedResistances.PressureDrop ( final dp_nominal=dp_nominal), redeclare model Model_pipDisSup = Buildings.Fluid.FixedResistances.LosslessPipe); parameter Modelica.Units.SI.PressureDifference dp_nominal(displayUnit="Pa") "Pressure drop at nominal mass flow rate"; Buildings.Fluid.FixedResistances.PressureDrop pipConRet( redeclare package Medium = MediumRet, m_flow_nominal=mCon_flow_nominal, final dp_nominal=dp_nominal) "Connection return pipe"; equation connect(port_aCon, pipConRet.port_a); connect(pipConRet.port_b, junConRet.port_3); connect(port_bCon, junConSup.port_3); end ConnectionCondensatePipe;

Buildings.Experimental.DHC.Networks.Steam.DistributionCondensatePipe Buildings.Experimental.DHC.Networks.Steam.DistributionCondensatePipe

Model of a steam distribution network using fixed resistance pipe model for condensate returns

Buildings.Experimental.DHC.Networks.Steam.DistributionCondensatePipe

Information

This is a model of a distribution network for steam heating systems. The model utilizes a split-medium approach with two separate medium declarations between liquid (condensate return) and vapor (steam supply) states. The piping network features:

Reference

Hinkelman, Kathryn, Saranya Anbarasu, Michael Wetter, Antoine Gautier, and Wangda Zuo. 2022. “A Fast and Accurate Modeling Approach for Water and Steam Thermodynamics with Practical Applications in District Heating System Simulation.” Preprint. February 24. doi:10.13140/RG.2.2.20710.29762.

Extends from Buildings.Experimental.DHC.Networks.BaseClasses.PartialDistribution2Pipe2Medium (Partial model for a two-pipe distribution network with two medium declarations).

Parameters

TypeNameDefaultDescription
replaceable package MediumSupPartialMediumMedium model for supply fluid
replaceable package MediumRetPartialMediumMedium model for return fluid
IntegernCon Number of connections
replaceable model Model_pipDisPartialTwoPortInterfaceModel for distribution pipe
Booleanshow_heaFlofalseSet to true to output the heat flow rate transferred to each connected load
Nominal condition
MassFlowRatemDis_flow_nominal Nominal mass flow rate in the distribution line before the first connection [kg/s]
MassFlowRatemCon_flow_nominal[nCon] Nominal mass flow rate in each connection line [kg/s]
MassFlowRatemEnd_flow_nominalmDis_flow_nominal - sum(mCon...Nominal mass flow rate in the end of the distribution line [kg/s]
MassFlowRatemDisCon_flow_nominal[nCon]cat(1, {mDis_flow_nominal}, ...Nominal mass flow rate in the distribution line before each connection [kg/s]
PressureDifferencedp_nominal Pressure drop at nominal mass flow rate [Pa]
Assumptions
BooleanallowFlowReversalfalse= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
Equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Type of energy balance: dynamic (3 initialization options) or steady state
Nominal condition
Timetau10Time constant at nominal flow for dynamic energy and momentum balance [s]

Connectors

TypeNameDescription
FluidPorts_aports_aCon[nCon]Connection return ports
FluidPorts_bports_bCon[nCon]Connection supply ports
FluidPort_aport_aDisSupDistribution supply inlet port
FluidPort_bport_bDisSupDistribution supply outlet port
replaceable model Model_pipDisModel for distribution pipe
FluidPort_bport_bDisRetDistribution return outlet port
FluidPort_aport_aDisRetDistribution return inlet port

Modelica definition

model DistributionCondensatePipe "Model of a steam distribution network using fixed resistance pipe model for condensate returns" extends Buildings.Experimental.DHC.Networks.BaseClasses.PartialDistribution2Pipe2Medium ( redeclare ConnectionCondensatePipe con[nCon]( each final dp_nominal=dp_nominal), redeclare model Model_pipDis=Buildings.Fluid.FixedResistances.LosslessPipe); parameter Modelica.Units.SI.PressureDifference dp_nominal(displayUnit="Pa") "Pressure drop at nominal mass flow rate"; end DistributionCondensatePipe;