.LibRAS.Tanks.PartialLumpedVessel

Information

This base class extends PartialLumpedVolume with a vector of fluid ports and a replaceable wall HeatTransfer model.

The following modeling assumption are made:

• homogeneous medium, i.e., phase separation is not taken into account,
• no kinetic energy in the fluid, i.e., kinetic energy dissipates into the internal energy,
• pressure loss definitions at vessel ports assume incompressible fluid,
• outflow of ambient media is prevented at each port assuming check valve behavior. If fluidlevel < portsData_height[i] and   ports[i].p < vessel_ps_static[i] mass flow at the port is set to 0.

Each port has a (hydraulic) diameter and a height above the bottom of the vessel, which can be configured using the  portsData record. Alternatively the impact of port geometries can be neglected with use_portsData=false. This might be useful for early design studies. Note that this means to assume an infinite port diameter at the bottom of the vessel. Pressure drops and heights of the ports as well as kinetic and potential energy fluid entering or leaving the vessel are neglected then.

The following variables need to be defined by an extending model:

• input fluidVolume, the volume of the fluid in the vessel,
• vessel_ps_static[nPorts], the static pressures inside the vessel at the height of the corresponding ports, at zero flow velocity, and
• Wb_flow, work term of the energy balance, e.g., p*der(V) if the volume is not constant or stirrer power.

An extending model should define:

• parameter vesselArea (default: Modelica.Constants.inf m2), the area of the vessel, to be related to cross flow areas of the ports for the consideration of dynamic pressure effects.

Optionally the fluid level may vary in the vessel, which effects the flow through the ports at configurable portsData_height[nPorts]. This is why an extending model with varying fluid level needs to define:

• input fluidLevel (default: 0m), the level the fluid in the vessel, and
• parameter fluidLevel_max (default: 1m), the maximum level that must not be exceeded. Ports at or above fluidLevel_max can only receive inflow.

An extending model should not access the portsData record defined in the configuration dialog, as an access to portsData may fail for use_portsData=false or nPorts=0.

Instead the predefined variables

• portsData_diameter[nPorts],
• portsData_height[nPorts],
• portsData_zeta_in[nPorts], and
• portsData_zeta_out[nPorts]

should be used if these values are needed.

Contents

Revisions

• Jan. 2009 by Rüdiger Franke: extended with
  • portsData record and threat configurable port heights,
  • consideration of kinetic and potential energy of fluid entering or leaving in energy balance
• Dec. 2008 by Rüdiger Franke: derived from OpenTank, in order to make general use of configurable port diameters