.Greenhouses.Components.HVAC.HeatStorageWaterHeater.Cell1DimInc_2ports

Information

This model describes the flow of an incompressible fluid through a single cell. An overall flow model can be obtained by interconnecting several cells in series (see Flow1DimInc).

Enthalpy is selected as state variable.

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 balance and on a static mass and momentum balances
• Constant pressure 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 model is characterized by two flow connector and one lumped thermal port connector. During normal operation the fluid enters the model from the InFlow connector and exits from the OutFlow connector. In case of flow reversal the fluid direction is inversed.

The thermal energy transfer through the lateral surface is computed by the ConvectiveHeatTransfer model which is inerithed in the Cell1DimInc model.

Modelling options

In the General tab the following options are available:

• Medium: the user has the possibility to easly switch Medium.
• HeatTransfer: the user can choose the thermal energy model he prefers

In the Initialization tab the following options are available:

• steadystate: If it sets to true, the derivative of enthalpy is sets to zero during Initialization

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. The authors raccomand the UpWind Scheme - AllowsFlowReversal in case flow reversal is expected.

Contents

Name	Description
Medium	Medium in the component
HeatTransfer	Convective heat transfer

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