modelPartialBoiler
Boiler base class with efficiency unspecified
Extends from Interfaces.TwoPortHeatMassExchanger (Partial model transporting one fluid stream with storing mass or energy).
Information
This is a base model of a boiler. The efficiency specified in extended models. See Buildings.Fluid.Boilers.UsersGuide for details.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | homotopyInitialization (from TwoPortHeatMassExchanger) | true | = true, use homotopy method |
| Buildings.Fluid.Data.Fuels.Generic | fue | Fuel type | |
| Modelica.Units.SI.HeatFlowRate | Q_flow_nominal | Nominal heating power (useful heat) | |
| Modelica.Units.SI.Efficiency | eta_nominal | Boiler efficiency at nominal condition, useful heat divided by fuel use | |
| Modelica.Units.SI.HeatFlowRate | QFue_flow_nominal | Q_flow_nominal/eta_nominal | Fuel use at nominal conditions |
| 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 |
| Heat loss to ambient | |||
| Modelica.Units.SI.ThermalConductance | UA | 0.05*Q_flow_nominal/30 | Overall UA value |
| Dynamics | |||
| Modelica.Units.SI.Volume | VWat | 1.5E-6*Q_flow_nominal | Water volume of boiler |
| Modelica.Units.SI.Mass | mDry | 1.5E-3*Q_flow_nominal | Mass of boiler that will be lumped to water heat capacity |
Connectors
| Type | Name | Default | 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 | Part load ratio | |
| Modelica.Blocks.Interfaces.RealOutput | T | Temperature of the fluid | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | heatPort | 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 | Boiler efficiency, useful heat divided by fuel use | |
| Modelica.Units.SI.HeatFlowRate | QFue_flow | y*QFue_flow_nominal | Heat released by fuel |
| Modelica.Units.SI.HeatFlowRate | QUse_flow | eta*QFue_flow | Useful heat for exchange with fluid ports |
| Modelica.Units.SI.HeatFlowRate | QExh_flow | -QFue_flow + QWat_flow | Heat exhausted by flu gas (negative) |
| Modelica.Units.SI.Power | QAmb_flow | heatPort.Q_flow | Heat loss to ambient (negative) |
| Modelica.Units.SI.Power | QWat_flow | QUse_flow - QAmb_flow | Heat transfer from gas into water (from where some heat is lost to ambient) |
| Modelica.Units.SI.MassFlowRate | mFue_flow | QFue_flow/fue.h | Fuel mass flow rate |
| Modelica.Units.SI.VolumeFlowRate | VFue_flow | mFue_flow/fue.d | Fuel volume flow rate |
| Modelica.Thermal.HeatTransfer.Components.HeatCapacitor | heaCapDry | Heat capacity of boiler metal | |
| Buildings.HeatTransfer.Sources.PrescribedHeatFlow | preHeaFlo | Prescribed heat flow | |
| Modelica.Blocks.Sources.RealExpression | Q_flow_in | Heat transfer from gas into water | |
| Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor | temSen | Temperature of fluid | |
| Modelica.Thermal.HeatTransfer.Components.ThermalConductor | UAOve | Overall thermal conductance (if heatPort is connected) |
Revisions
-
October 11, 2026, by Michael Wetter:
Corrected bug that led to heat loss of boiler to be accounted twice in the energy balance. With this change, theheatPortmust be connected, as otherwise, the heat loss is not properly calculated. The translation will stop with an error message if theheatPortis unconnected.
This is for #4775. -
November 10, 2021, by Hongxiang Fu:
The heating power output of the boiler is now corrected by its heat loss to the ambient. This is for #2725. -
October 4, 2021, by Hongxiang Fu:
Renamed from the old Buildings.Fluid.Boilers.BoilerPolynomial and with the efficiency specification removed. This is for #2651.