This is a model of a boiler whose efficiency is described by a polynomial. The heat input into the medium is

Q̇ = y Q̇_{0}
η ⁄ η_{0}

where *y ∈ [0, 1]* is the control signal,
*Q̇ _{0}* is the nominal power,

`T_nominal`

.The parameter `effCur`

determines what polynomial is
used to compute the efficiency, which is defined as

η = Q̇ ⁄
Q̇_{f},

where *Q̇* is the heat transferred to the working fluid
(typically water or air), and *Q̇ _{f}* is the heat of
combustion released by the fuel.

The following polynomials can be selected to compute the efficiency:

Parameter `effCur` |
Efficiency curve |
---|---|

Buildings.Fluid.Types.EfficiencyCurves.Constant | η = a_{1} |

Buildings.Fluid.Types.EfficiencyCurves.Polynomial | η = a_{1} + a_{2} y + a_{3}
y^{2} + ... |

Buildings.Fluid.Types.EfficiencyCurves.QuadraticLinear | η = a_{1} + a_{2} y + a_{3}
y^{2} + (a_{4} + a_{5} y + a_{6}
y^{2}) 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.

The parameter `Q_flow_nominal`

is the power
transferred to the fluid for `y=1`

and, if the
efficiency depends on temperature, for `T=T0`

.

The fuel mass flow rate and volume flow rate are computed as

ṁ_{f} =
Q̇_{f} ⁄ h_{f}

and

V̇_{f} =
ṁ_{f} ⁄ ρ_{f},

where the fuel heating value *h _{f}* and the fuel
mass density

`fue`

. Note that if Optionally, the port `heatPort`

can be connected to a
heat port outside of this model to impose a boundary condition in
order to model heat losses to the ambient. When using this
`heatPort`

, make sure that the efficiency curve
`effCur`

does not already account for this heat
loss.

On the Assumptions tag, the model can be parameterized to compute a transient or steady-state response. The transient response of the boiler is computed using a first order differential equation to compute the boiler's water and metal temperature, which are lumped into one state. The boiler outlet temperature is equal to this water temperature.

- 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.

- Removed parameter
- January 29, 2009 by Michael Wetter:

First implementation.

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