FAQ Category: Modeling

Please use the ‘DefineVolumeFlow’ and ‘ExtractVolumeFlow’ elements under GreenCity.Interfaces.Thermal. This allows you to apply a constant assumed temperature and volume flow to a heating circuit, for example, in order to be able to easily check numerical effects in the downstream model area or an initial model reaction.

Always start by modelling the load(s) (building, heating loads, hot water, cooling load, etc.). Cut out thermal circuits and simulate the submodels individually in order to recognise and solve subsystem errors at an early stage. Continue successively with distributions, storage tanks, generators and their control and repeatedly carry out test simulations. If the problems continue,…

Heat storage tanks are defined in Green City as layers of superimposed media (usually water). The number of layers is set via the parameter ‘n’. Each connection (1 to 6) is assigned a layer index as the inlet or outlet height. This is also done via separate indices (iFlow or iReturn). If these indices exceed…

Transformers are treated differently in the equation system of Green City models due to the definition of the voltage level. Therefore, please select the ‘Transformer’ option for the ‘OutputType’ parameter in the grid model. You will then receive an additional connector for connecting a transformer above the model. The procedure is similar for hierarchical grids…

Green City models utilise existing knowledge to increase simulation performance. This includes the fact that the direction of the media flow in a heating system is usually unidirectional. In order to avoid numerical problems in the model (i.e. overdetermination of the system of equations), only the output volume flows are set in the ‘Pump’ model…

Green City uses a predefined direction of movement of the media flow. Therefore, connectors of the type ‘VolumeFlowIn’ (coloured red circle as symbol) indicate that the media flow enters the model at this point and connectors of the type ‘VolumeFlowOut’ (red circle with white inner surface) indicate that the media flow exits the model at…