Expansion Tank


The model ExpansionTank describes the storage of fluid in liquid phase in a closed volume filled with gas.

Pressure and enthalpy are selected as state variables.

The assumptions for this model are:

  • The gas is considered ideal and using Boyle’s law: p_gas*V_gas = Const = pstart*V_gas
  • The gas is considered at the same temperature of the fluid
  • The model is based on dynamic mass and energy balances of the fluid
  • The static pressure head due to the liquid level is taken into account
  • Thermal energy transfer due to external air convection through the tank surface (lateral+top+bottom) is ensured by the TankWall connector. The actual heat flow is computed by the thermal energy model
  • Minimum liquid level with respect to tank height= 0
  • Maximum liquid level with respect to tank height= 0.5

The model is characterized by one flow connector.

The thermal energy transfer through the Tank surface is computed by the ConvectiveHeatTransfer model which is inerithed in the ExpansionTank model

Modelling options

In the General tab the following options are availabe:

  • Medium: the user has the possibility to easly switch Medium.
  • HeatTransfer: selection between the different heat transfer models available in ThermoCycle