modelBoilerPolynomial

Boiler with efficiency curve described by a polynomial of the control signal and (optional) temperature

Extends from Buildings.Fluid.Boilers.BaseClasses.PartialBoiler (Boiler base class with efficiency unspecified).

Information

This is a model of a boiler whose efficiency is described by a polynomial. See Buildings.Fluid.Boilers.UsersGuide for details.

The parameter effCur determines what polynomial is used to compute the efficiency with the following selections:

Parameter effCur	Efficiency curve
Buildings.Fluid.Types.EfficiencyCurves.Constant	η = a₁
Buildings.Fluid.Types.EfficiencyCurves.Polynomial	η = a₁ + a₂ y + a₃ y² + ...
Buildings.Fluid.Types.EfficiencyCurves.QuadraticLinear	η = a₁ + a₂ y + a₃ y² + (a₄ + a₅ y + a₆ y²) T

where T is the boiler outlet temperature in Kelvin. For effCur = Buildings.Fluid.Types.EfficiencyCurves.Polynomial, an arbitrary number of polynomial coefficients can be specified.

Parameters

Type	Name	Default	Description
Boolean	homotopyInitialization (from TwoPortHeatMassExchanger)	true	= true, use homotopy method
Buildings.Fluid.Data.Fuels.Generic	fue (from PartialBoiler)		Fuel type
Modelica.Units.SI.Power	Q_flow_nominal (from PartialBoiler)		Nominal heating power
Modelica.Units.SI.ThermalConductance	UA (from PartialBoiler)	0.05*Q_flow_nominal/30	Overall UA value
Modelica.Units.SI.Efficiency	eta_nominal (from PartialBoiler)		Boiler efficiency at nominal condition
Buildings.Fluid.Types.EfficiencyCurves	effCur	Buildings.Fluid.Types.EfficiencyCurves.Constant	Curve used to compute the efficiency
Real[:]	a	{0.9}	Coefficients for efficiency curve
Modelica.Units.SI.Temperature	T_nominal	353.15	Temperature used to compute nominal efficiency (only used if efficiency curve depends on temperature)
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
Dynamics › Nominal condition
Modelica.Units.SI.Time	tau (from TwoPortHeatMassExchanger)	30	Time constant at nominal flow (if energyDynamics <> SteadyState)
Dynamics › Conservation equations
Modelica.Fluid.Types.Dynamics	energyDynamics (from TwoPortHeatMassExchanger)	Modelica.Fluid.Types.Dynamics.DynamicFreeInitial	Type of energy balance: dynamic (3 initialization options) or steady state
Initialization
Medium.AbsolutePressure	p_start (from TwoPortHeatMassExchanger)	Medium.p_default	Start value of pressure
Medium.Temperature	T_start (from TwoPortHeatMassExchanger)	Medium.T_default	Start value of temperature
Medium.MassFraction[Medium.nX]	X_start (from TwoPortHeatMassExchanger)	Medium.X_default	Start value of mass fractions m_i/m
Medium.ExtraProperty[Medium.nC]	C_start (from TwoPortHeatMassExchanger)	fill(0, Medium.nC)	Start value of trace substances
Dynamics
Modelica.Units.SI.Volume	VWat (from PartialBoiler)	1.5E-6*Q_flow_nominal	Water volume of boiler
Modelica.Units.SI.Mass	mDry (from PartialBoiler)	1.5E-3*Q_flow_nominal	Mass of boiler that will be lumped to water heat capacity

Connectors

Type	Name	Description
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)
Modelica.Blocks.Interfaces.RealInput	y (from PartialBoiler)	Part load ratio
Modelica.Blocks.Interfaces.RealOutput	T (from PartialBoiler)	Temperature of the fluid
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a	heatPort (from PartialBoiler)	Heat port, can be used to connect to ambient

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.MixingVolumes.MixingVolume	vol (from TwoPortHeatMassExchanger)
Buildings.Fluid.FixedResistances.PressureDrop	preDro (from TwoPortHeatMassExchanger)		Flow resistance
Modelica.Units.SI.Efficiency	eta (from PartialBoiler)		Boiler efficiency
Modelica.Units.SI.Power	QFue_flow (from PartialBoiler)	y*Q_flow_nominal/eta_nominal	Heat released by fuel
Modelica.Units.SI.Power	QWat_flow (from PartialBoiler)	eta*QFue_flow + UAOve.Q_flow	Heat transfer from gas into water
Modelica.Units.SI.MassFlowRate	mFue_flow (from PartialBoiler)	QFue_flow/fue.h	Fuel mass flow rate
Modelica.Units.SI.VolumeFlowRate	VFue_flow (from PartialBoiler)	mFue_flow/fue.d	Fuel volume flow rate
Modelica.Thermal.HeatTransfer.Components.HeatCapacitor	heaCapDry (from PartialBoiler)		Heat capacity of boiler metal
Buildings.HeatTransfer.Sources.PrescribedHeatFlow	preHeaFlo (from PartialBoiler)		Prescribed heat flow
Modelica.Blocks.Sources.RealExpression	Q_flow_in (from PartialBoiler)		Heat transfer from gas into water
Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor	temSen (from PartialBoiler)		Temperature of fluid
Modelica.Thermal.HeatTransfer.Components.ThermalConductor	UAOve (from PartialBoiler)		Overall thermal conductance (if heatPort is connected)

Revisions

March 7, 2022, by Michael Wetter:
Set final massDynamics=energyDynamics.
This is for #1542.
October 13, 2021, by Hongxiang Fu:
For the implementation of Buildings.Fluid.Boilers.BoilerTable, moved most of the code to the base model Buildings.Fluid.Boilers.BaseClasses.PartialBoiler. This is for #2651.
May 27, 2016, by Michael Wetter:
Corrected size of input argument to Buildings.Utilities.Math.Functions.quadraticLinear for JModelica compliance check.
May 30, 2014, by Michael Wetter:
Removed undesirable annotation Evaluate=true.
October 9, 2013 by Michael Wetter:
Removed conditional declaration of mDry as the use of a conditional parameter in an instance declaration is not correct Modelica syntax.
December 14, 2012 by Michael Wetter:
Renamed protected parameters for consistency with the naming conventions.
December 22, 2011 by Michael Wetter:
Added computation of fuel usage and improved the documentation.
May 25, 2011 by Michael Wetter:
- Removed parameter dT_nominal, and require instead the parameter m_flow_nominal to be set by the user. This was needed to avoid a non-literal value for the nominal attribute of the pressure drop model.
- Changed assignment of parameters in model instantiation, and updated model for the new base class that does not have a temperature sensor.
January 29, 2009 by Michael Wetter:
First implementation.