Parameterization and Extension of Interfaces

1 Tank

External interfaces to component classes are defined primarily through the use of connectors. Assume that we have a definition of a Tank model in a model library. The model has an external interface in terms of the connectors inlet and outlet, as well as a formal class parameter TankStream which is a connector class with its default class value being the Stream connector class. (See ModelicaBook page 176)

connector Stream //Connector class Real pressure; flow Real volumeFlowRate; end Stream;
model Tank parameter Real area = 1; replaceable connector TankStream = Stream; // Class parameterization TankStream inlet, outlet; // The connectors Real level(start=2); equation // Mass balance area * der(level) = inlet.volumeFlowRate + outlet.volumeFlowRate; outlet.pressure = inlet.pressure; end Tank;

1.1 Instantiation of Tank

instantiateModel( Tank )

2 HeatTank

We would like to extend the Tank model to include temperature dependent effects, analogous to how we extended a resistor to a temperature dependent resistor.

connector HeatStream extends Stream; Real temp; end HeatStream;
model HeatTank extends Tank(redeclare connector TankStream = HeatStream); Real level(start=2); Real temp; equation // Energy balance for temperature effects area*level*der(temp) = inlet.volumeFlowRate*inlet.temp + outlet.volumeFlowRate*outlet.temp; outlet.temp = temp; // Perfect mixing assumed. end HeatTank;

2.1 Instantiation of HeatTank

Instantiate it:

instantiateModel(HeatTank) // 2015-09-08 - Warning about non-balanced connector OK?

3 HeatTankExpanded

The definition of HeatTank is equivalent to the definition of HeatTankExpanded

model HeatTankExpanded //Modelica Book version, Added start values etc. parameter Real area=1; // and some inlet and outlet equations TankStream inlet, outlet; Real level(start=2); Real temp; connector TankStream Real pressure; flow Real volumeFlowRate; Real temp; end TankStream; equation // Mass balance: area*der(level) = inlet.volumeFlowRate + outlet.volumeFlowRate; outlet.pressure = inlet.pressure; // Energy balance: area*level*der(temp) = inlet.volumeFlowRate * inlet.temp + outlet.volumeFlowRate * outlet.temp; outlet.temp = temp; end HeatTankExpanded;
instantiateModel(HeatTankExpanded)

4 TODO provide simulation model