This example shows how to use a Modelica model to solve for some unknown parameters, given some desired system output (please look at the Modelica textual code). In this case, the nominal heat transfer coefficient Plant.Boiler.gamma_nom is computed in order to obtain an initial value of the gas outlet temperature equal to 130 degrees Celsius. This can be used to match the model to known design data. Note that steady-state initial conditions are required to make the computation meaningful.
This is performed by defining a gamma_unknown parameter at the top level, with a fixed = false attribute (meaning that its value is a unknown) and with a start = 150 attribute to provide a reasonable initial guess for the solver. This parameter is then used to override the value of Plant.Boiler.gamma_nom. In order to obtain a closed initialization problem, a corresponding initial equation to set the desired value of Plant.GasOut.T is added.
The transient starts at steady state, with the desired values of the heat transfer coefficient and gas outlet temperature. At time t = 100 s, the water valve is closed by 10%. At time t = 200 s, the gas flow rate is increased by 10%.