Buildings.Fluid.Boilers
Package with boiler models
Information
This package contains components models for boilers.Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Package Content
| Name | Description |
|---|---|
 UsersGuide
|
User's Guide |
 BoilerPolynomial
|
Boiler with efficiency curve described by a polynomial of the control signal and (optional) temperature |
 BoilerTable
|
Boiler with efficiency described by a table with control signal and inlet temperature |
 Data
|
Package containing performance data for boilers |
 Examples
|
Collection of models that illustrate model use and test models |
| Validation
|
Collection of validation models |
 BaseClasses
|
Package with base classes for Buildings.Fluid.Boilers |
Buildings.Fluid.Boilers.BoilerPolynomial
Boiler with efficiency curve described by a polynomial of the control signal and (optional) temperature
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.
Extends from Buildings.Fluid.Boilers.BaseClasses.PartialBoiler (Boiler base class with efficiency unspecified).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Generic | fue | Fuel type | |
| Power | Q_flow_nominal | Nominal heating power [W] | |
| ThermalConductance | UA | 0.05*Q_flow_nominal/30 | Overall UA value [W/K] |
| Efficiency | eta_nominal | if effCur == Buildings.Fluid... | Boiler efficiency at nominal condition [1] |
| Efficiency | eta | if effCur == Buildings.Fluid... | Boiler efficiency [1] |
| EfficiencyCurves | effCur | Buildings.Fluid.Types.Effici... | Curve used to compute the efficiency |
| Real | a[:] | {0.9} | Coefficients for efficiency curve |
| Temperature | T_nominal | 353.15 | Temperature used to compute nominal efficiency (only used if efficiency curve depends on temperature) [K] |
| Nominal condition | |||
| MassFlowRate | m_flow_nominal | Nominal mass flow rate [kg/s] | |
| PressureDifference | dp_nominal | Pressure difference [Pa] | |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| 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 | true | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Boolean | from_dp | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics | |||
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Volume | VWat | 1.5E-6*Q_flow_nominal | Water volume of boiler [m3] |
| Mass | mDry | 1.5E-3*Q_flow_nominal | Mass of boiler that will be lumped to water heat capacity [kg] |
| Initialization | |||
| AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa] |
| Temperature | T_start | Medium.T_default | Start value of temperature [K] |
| MassFraction | X_start[Medium.nX] | Medium.X_default | Start value of mass fractions m_i/m [kg/kg] |
| ExtraProperty | C_start[Medium.nC] | fill(0, Medium.nC) | Start value of trace substances |
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) |
| input RealInput | y | Part load ratio |
| output RealOutput | T | Temperature of the fluid [K] |
| HeatPort_a | heatPort | Heat port, can be used to connect to ambient |
Modelica definition
model BoilerPolynomial
"Boiler with efficiency curve described by a polynomial of the control signal and (optional) temperature"
extends Buildings.Fluid.Boilers.BaseClasses.PartialBoiler(
eta=if effCur ==Buildings.Fluid.Types.EfficiencyCurves.Constant then
a[1]
elseif effCur ==Buildings.Fluid.Types.EfficiencyCurves.Polynomial then
Buildings.Utilities.Math.Functions.polynomial(a=a, x=y)
elseif effCur ==Buildings.Fluid.Types.EfficiencyCurves.QuadraticLinear then
Buildings.Utilities.Math.Functions.quadraticLinear(a=aQuaLin, x1=y, x2=T)
else
0,
final eta_nominal = if effCur ==Buildings.Fluid.Types.EfficiencyCurves.Constant then
a[1]
elseif effCur ==Buildings.Fluid.Types.EfficiencyCurves.Polynomial then
Buildings.Utilities.Math.Functions.polynomial(a=a, x=1)
elseif effCur ==Buildings.Fluid.Types.EfficiencyCurves.QuadraticLinear then
Buildings.Utilities.Math.Functions.quadraticLinear(a=aQuaLin, x1=1, x2=T_nominal)
else
999);
parameter Buildings.Fluid.Types.EfficiencyCurves
effCur=Buildings.Fluid.Types.EfficiencyCurves.Constant
"Curve used to compute the efficiency";
parameter Real a[:] = {0.9} "Coefficients for efficiency curve";
parameter Modelica.Units.SI.Temperature T_nominal=353.15
"Temperature used to compute nominal efficiency (only used if efficiency curve depends on temperature)";
protected
parameter Real aQuaLin[6] = if size(a, 1) == 6 then a else fill(0, 6)
"Auxiliary variable for efficiency curve because quadraticLinear requires exactly 6 elements";
initial equation
if effCur == Buildings.Fluid.Types.EfficiencyCurves.QuadraticLinear then
assert(size(a, 1) == 6,
"The parameter 'a' must have exactly 6 elements
when the boiler efficiency curve is set to
'Buildings.Fluid.Types.EfficiencyCurves.QuadraticLinear'.
The number of elements currently supplied is " + String(size(a, 1)) + ".");
end if;
end BoilerPolynomial;
Buildings.Fluid.Boilers.BoilerTable
Boiler with efficiency described by a table with control signal and inlet temperature
Information
This is a model of a boiler whose efficiency is described by a table with control signal and inlet temperature. See Buildings.Fluid.Boilers.UsersGuide for details.
The efficiency tables are supplied via Buildings.Fluid.Boilers.Data.
Extends from Buildings.Fluid.Boilers.BaseClasses.PartialBoiler (Boiler base class with efficiency unspecified).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Generic | fue | per.fue | Fuel type |
| Power | Q_flow_nominal | per.Q_flow_nominal | Nominal heating power [W] |
| ThermalConductance | UA | per.UA | Overall UA value [W/K] |
| Efficiency | eta_nominal | per.eta_nominal | Boiler efficiency at nominal condition [1] |
| Efficiency | eta | effTab.y | Boiler efficiency [1] |
| Generic | per | Records of efficiency curves | |
| Nominal condition | |||
| MassFlowRate | m_flow_nominal | per.m_flow_nominal | Nominal mass flow rate [kg/s] |
| PressureDifference | dp_nominal | per.dp_nominal | Pressure difference [Pa] |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| 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 | true | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Boolean | from_dp | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics | |||
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Volume | VWat | per.VWat | Water volume of boiler [m3] |
| Mass | mDry | per.mDry | Mass of boiler that will be lumped to water heat capacity [kg] |
| Initialization | |||
| AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa] |
| Temperature | T_start | Medium.T_default | Start value of temperature [K] |
| MassFraction | X_start[Medium.nX] | Medium.X_default | Start value of mass fractions m_i/m [kg/kg] |
| ExtraProperty | C_start[Medium.nC] | fill(0, Medium.nC) | Start value of trace substances |
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) |
| input RealInput | y | Part load ratio |
| output RealOutput | T | Temperature of the fluid [K] |
| HeatPort_a | heatPort | Heat port, can be used to connect to ambient |
Modelica definition
model BoilerTable
"Boiler with efficiency described by a table with control signal and inlet temperature"
extends Buildings.Fluid.Boilers.BaseClasses.PartialBoiler(
final eta=effTab.y,
final Q_flow_nominal = per.Q_flow_nominal,
final eta_nominal= per.eta_nominal,
final fue=per.fue,
final UA=per.UA,
final VWat = per.VWat,
final mDry = per.mDry,
final m_flow_nominal = per.m_flow_nominal,
final dp_nominal = per.dp_nominal);
parameter Buildings.Fluid.Boilers.Data.Generic per
"Records of efficiency curves";
Modelica.Blocks.Tables.CombiTable2Ds effTab(final table=per.effCur, final
smoothness=Modelica.Blocks.Types.Smoothness.ContinuousDerivative)
"Look-up table that represents a set of efficiency curves varying with both the firing rate (control signal) and the inlet water temperature";
Modelica.Blocks.Sources.RealExpression TIn(
y=Medium.temperature(state=Medium.setState_phX(
p=port_a.p, h=inStream(port_a.h_outflow), X=inStream(port_a.Xi_outflow))))
"Water inlet temperature";
initial equation
assert(abs(per.effCur[end,1] - 1) < 1E-6,
"Efficiency curve at full load (y = 1) must be provided.");
equation
connect(effTab.u1, y);
connect(TIn.y, effTab.u2);
end BoilerTable;