modelCellConst

1-D fluid flow model (finite volume discretization - ideal fluid model)

Information

Model CellConst describes the flow of a constant specific heat fluid through a single cell. An overall flow model can be obtained by interconnecting several cells in series (see Flow1DConst)

Two types of variables can be distinguished: cell variables and node variables. Node variables are characterized by the su (supply) and ex (exhaust) subscripts, and correspond to the inlet and outlet nodes at each cell. The relation between the cell and node values depends on the discretization scheme selected.

The assumptions for this model are:

  • Velocity is considered uniform on the cross section. 1-D lumped parameter model
  • The model is based on dynamic energy balances and on a static mass and momentum balance
  • Constant pressure is assumed in the cell
  • Constant heat capacity is assumed in the cell
  • Axial thermal energy transfer is neglected
  • Thermal energy transfer through the lateral surface is ensured by the wall_int connector. The actual heat flow is computed by the thermal energy model

The thermal energy transfer through the lateral surface is computed by the ConvectiveHeatTransfer model which is inerithed in the CellConst model.

Modelling options

In the General tab the following option is availabe:

  • HeatTransfer: the user can choose the thermal energy model he prefers

Numerical options

In this tab several options are available to make the model more robust:

  • Discretization: 2 main discretization options are available: UpWind and central difference method.

Parameters

TypeNameDefaultDescription
IntegerNt1Number of cells in parallel
Modelica.SIunits.VolumeViVolume of a single cell
Modelica.SIunits.AreaAiLateral surface of a single cell
Modelica.SIunits.MassFlowRateMdotnom3Norminal fluid flow rate
Modelica.SIunits.CoefficientOfHeatTransferUnom500Nominal heat transfer coefficient,secondary fluid
Initialization
Modelica.SIunits.TemperatureTstart145 + 273.15Start value of temperature vector (initialized by default)
Numerical options
DiscretizationsDiscretizationThermoCycle.Functions.Enumerations.Discretizations.centr_diffSelection of the spatial discretization scheme
Initialization › Intialization options
Booleansteadystatetrueif true, sets the derivative of T to zero during Initialization

Connectors

TypeNameDefaultDescription
Interfaces.Fluid.Flange_CdotInFlow
Interfaces.Fluid.Flange_ex_CdotOutFlow
Interfaces.HeatTransfer.ThermalPortLWall_int

Components

TypeNameDefaultDescription
Modelica.SIunits.TemperatureT_su
Modelica.SIunits.MassFlowRateMdot
Modelica.SIunits.SpecificHeatCapacitycp
Modelica.SIunits.Densityrho_su
Modelica.SIunits.TemperatureTNode temperatures
Modelica.SIunits.TemperatureTnode_su
Modelica.SIunits.TemperatureTnode_ex
Modelica.SIunits.HeatFluxqdotAverage heat flux
Modelica.SIunits.PowerQ_totTotal heat flux exchanged by the thermal port
Modelica.SIunits.MassM_totTotal mass
HeatTransferheatTransfer

Contents

NameDescription
HeatTransfer