modelSingleCircuitSlab

Model of a single circuit of a radiant slab

Extends from Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.Slab (Base class for radiant slab), Buildings.Fluid.FixedResistances.BaseClasses.Pipe (Model of a pipe with finite volume discretization along the flow path).

Information

This is a model of a single flow circuit of a radiant slab with pipes or a capillary heat exchanger embedded in the construction. For a model with multiple parallel flow circuits, see Buildings.Fluid.HeatExchangers.RadiantSlabs.ParallelCircuitsSlab.

See the user's guide for more information.

Parameters

Type	Name	Default	Description
Buildings.Fluid.HeatExchangers.RadiantSlabs.Types.SystemType	sysTyp (from Slab)		Radiant system type
Modelica.Units.SI.Distance	disPip (from Slab)		Pipe distance
Buildings.Fluid.Data.Pipes.Generic	pipe (from Slab)		Record for pipe geometry and material
Boolean	homotopyInitialization (from Pipe)	true	= true, use homotopy method
Integer	nSeg (from Pipe)	10	Number of volume segments
Modelica.Units.SI.Length	thicknessIns (from Pipe)		Thickness of insulation
Modelica.Units.SI.ThermalConductivity	lambdaIns (from Pipe)		Heat conductivity of insulation
Modelica.Units.SI.Length	diameter (from Pipe)		Pipe diameter (without insulation)
Modelica.Units.SI.Length	length (from Pipe)		Length of the pipe
Buildings.Fluid.HeatExchangers.RadiantSlabs.Types.HeatTransfer	heatTransfer	Types.HeatTransfer.EpsilonNTU	Model for heat transfer between fluid and slab
Modelica.Units.SI.Velocity	v_nominal	4*m_flow_nominal/pipe.dIn^2/Modelica.Constants.pi/rho_default	Velocity at m_flow_nominal
Construction
HeatTransfer.Data.OpaqueConstructions.Generic	layers (from Slab)		Definition of the construction, which must have at least two material layers
Integer	iLayPip (from Slab)		Number of the interface layer in which the pipes are located
Modelica.Units.SI.Area	A		Surface area of radiant slab
Initialization › Construction
Boolean	steadyStateInitial (from Slab)	false	=true initializes dT(0)/dt=0, false initializes T(0) at fixed temperature using T_a_start, T_c_start and T_b_start
Modelica.Units.SI.Temperature	T_a_start (from Slab)	293.15	Initial temperature at surf_a, used if steadyStateInitial = false
Modelica.Units.SI.Temperature	T_b_start (from Slab)	293.15	Initial temperature at surf_b, used if steadyStateInitial = false
Modelica.Units.SI.Temperature	T_c_start	(T_a_startcon_b[1].layers.R + T_b_startcon_a[1].layers.R)/layers.R	Initial construction temperature in the layer that contains the pipes, used if steadyStateInitial = false
Dynamics
Boolean	stateAtSurface_a (from Slab)	true	=true, a state will be at the surface a
Boolean	stateAtSurface_b (from Slab)	true	=true, a state will be at the surface b
Real	mSenFac (from LumpedVolumeDeclarations)	1	Factor for scaling the sensible thermal mass of the volume
Dynamics › Conservation equations
Modelica.Fluid.Types.Dynamics	energyDynamics (from LumpedVolumeDeclarations)	Modelica.Fluid.Types.Dynamics.DynamicFreeInitial	Type of energy balance: dynamic (3 initialization options) or steady state
Modelica.Fluid.Types.Dynamics	substanceDynamics (from LumpedVolumeDeclarations)	energyDynamics	Type of independent mass fraction balance: dynamic (3 initialization options) or steady state
Modelica.Fluid.Types.Dynamics	traceDynamics (from LumpedVolumeDeclarations)	energyDynamics	Type of trace substance balance: dynamic (3 initialization options) or steady state
Advanced › Dynamics
Modelica.Fluid.Types.Dynamics	massDynamics (from LumpedVolumeDeclarations)	energyDynamics	Type of mass balance: dynamic (3 initialization options) or steady state, must be steady state if energyDynamics is steady state
Initialization
Medium.AbsolutePressure	p_start (from LumpedVolumeDeclarations)	Medium.p_default	Start value of pressure
Medium.Temperature	T_start (from LumpedVolumeDeclarations)	Medium.T_default	Start value of temperature
Medium.MassFraction[Medium.nX]	X_start (from LumpedVolumeDeclarations)	Medium.X_default	Start value of mass fractions m_i/m
Medium.ExtraProperty[Medium.nC]	C_start (from LumpedVolumeDeclarations)	fill(0, Medium.nC)	Start value of trace substances
Medium.ExtraProperty[Medium.nC]	C_nominal (from LumpedVolumeDeclarations)	fill(1E-2, Medium.nC)	Nominal value of trace substances. (Set to typical order of magnitude.)
Assumptions
Boolean	allowFlowReversal (from PartialTwoPort)	true	= false to simplify equations, assuming, but not enforcing, no flow reversal
Nominal condition
Modelica.Units.SI.MassFlowRate	m_flow_nominal (from PartialTwoPortInterface)		Nominal mass flow rate
Modelica.Units.SI.PressureDifference	dp_nominal (from TwoPortFlowResistanceParameters)		Pressure difference
Advanced
Modelica.Units.SI.MassFlowRate	m_flow_small (from PartialTwoPortInterface)	1E-4*abs(m_flow_nominal)	Small mass flow rate for regularization of zero flow
Advanced › Diagnostics
Boolean	show_T (from PartialTwoPortInterface)	false	= true, if actual temperature at port is computed
Flow resistance
Boolean	computeFlowResistance (from TwoPortFlowResistanceParameters)	true	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp (from TwoPortFlowResistanceParameters)	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Real	n (from TwoPortFlowResistanceParameters)	2	Flow exponent, n=1 for laminar, n=2 for turbulent
Boolean	linearizeFlowResistance (from TwoPortFlowResistanceParameters)	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM (from TwoPortFlowResistanceParameters)	0.1	Fraction of nominal flow rate where flow transitions to laminar
Real	ReC (from Pipe)	4000	Reynolds number where transition to turbulence starts

Connectors

Type	Name	Description
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a	surf_a (from Slab)	Heat port at construction surface
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a	surf_b (from Slab)	Heat port at construction surface
Modelica.Fluid.Interfaces.FluidPort_a	port_a (from PartialTwoPort)	Fluid connector a (positive design flow direction is from port_a to port_b)
Modelica.Fluid.Interfaces.FluidPort_b	port_b (from PartialTwoPort)	Fluid connector b (positive design flow direction is from port_a to port_b)

Components

Type	Name	Default	Description
Modelica.Units.SI.MassFlowRate	m_flow (from PartialTwoPortInterface)	port_a.m_flow	Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction)
Modelica.Units.SI.PressureDifference	dp (from PartialTwoPortInterface)	port_a.p - port_b.p	Pressure difference between port_a and port_b
Medium.ThermodynamicState	sta_a (from PartialTwoPortInterface)	if allowFlowReversal then Medium.setState_phX(port_a.p, noEvent(actualStream(port_a.h_outflow)), noEvent(actualStream(port_a.Xi_outflow))) else Medium.setState_phX(port_a.p, noEvent(inStream(port_a.h_outflow)), noEvent(inStream(port_a.Xi_outflow)))	Medium properties in port_a
Medium.ThermodynamicState	sta_b (from PartialTwoPortInterface)	if allowFlowReversal then Medium.setState_phX(port_b.p, noEvent(actualStream(port_b.h_outflow)), noEvent(actualStream(port_b.Xi_outflow))) else Medium.setState_phX(port_b.p, noEvent(port_b.h_outflow), noEvent(port_b.Xi_outflow))	Medium properties in port_b
Buildings.Fluid.FixedResistances.PressureDrop	preDro (from Pipe)		Flow resistance
Buildings.Fluid.MixingVolumes.BaseClasses.MixingVolumeHeatPort	vol (from Pipe)		Volume for pipe fluid
Buildings.HeatTransfer.Conduction.MultiLayer[nSeg]	con_a		Construction near the surface port surf_a
Buildings.HeatTransfer.Conduction.MultiLayer[nSeg]	con_b		Construction near the surface port surf_b

Revisions

October 18, 2017, by Michael Wetter:
Removed state at surface b of con_b. As this surface is connected to surface a of con_a, which already has a state, the state can be removed, rather than relying on the symbolic processor to remove one of these two states that are directly coupled. This is indeed required to avoid a warning about overdetermined initial equations.
January 06, 2016, by Thierry S. Nouidui:
Renamed parameter nSta2 to nSta.
November 17, 2016, by Thierry S. Nouidui:
Added parameter nSta2 to avoid translation error in Dymola 2107. This is a work-around for a bug in Dymola which will be addressed in future releases.
February 5, 2015, by Michael Wetter:
Renamed res to preDro for #292.
September 12, 2014, by Michael Wetter:
Set start value for hPip(fluid(T)) to avoid a warning about conflicting start values in Dymola 2015 FD01.
February 27, 2013, by Michael Wetter:
Fixed bug in the assignment of the fictitious thermal resistance by replacing RFic[nSeg](each G=A/Rx) with RFic[nSeg](each G=A/nSeg/Rx).
April 5, 2012, by Michael Wetter:
Revised implementation.
April 3, 2012, by Xiufeng Pang:
First implementation.