modelFreeConvection
Information
This component links the heat flow to a temperature difference between a wall and a fluid thanks to the Newton's law of cooling. The basic constitutive equation for convection is :
Where :
- Q_flow: Heat flow rate from connector 'wall' (e.g., a plate) to connector 'fluid' (e.g., the surrounding air).
- add_on is a user paramater to adjust if needed the Heat flow to the temperature difference dT
- h_cv is the convective Heat transfer coefficient (Newton's coefficient)
- A is the contact surface area between the wall and the fluid
- dT is the Temperature difference between the wall (port_a.T) and the fluid (port_b.T)
The Heat Transfert coefficient is calculated from correlations. The correlation is set via the parameter correlation . Multiple correlations from multiple sources and for severals geometries are available. The details of correlations is in the released theoretical note.
Available geometries:
- Flow over a flat vertical wall: the characteristic length (Lc parameter) is the height of the wall
- Cross flow over a horizontal cylinder: the characteristic length (Lc parameter) is external diameter of the cylinder
- Flow over a horizontal flat wall: the characteristic length (Lc parameter) is the perimeter of the flat wall. A particular attention is required when dealing with horizontal surfaces. The correlation has to be ground_ASHRAE if the fluid is above the wall and ceiling_ASHRAE otherwise. The exchange coefficient is calculated differently depending on whether the wall is warmer or not.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | add_on | 1 | Custom add-on |
| Geometrical properties | |||
| SI.Area | A | 0 | Wall surface Area |
| SI.Length | Lc | 1 | characteritic dimension for correlation |
| Flow properties | |||
| TAeZoSysPro.HeatTransfer.Types.FreeConvectionCorrelation | correlation | Correlations.vertical_plate_ASHRAE | Free convection Correlation |
| SI.CoefficientOfHeatTransfer | h_cv_const | 0 | constant heat transfer coefficient (optional: if correlation 'Constant' choosen) |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| HeatTransfer.Interfaces.HeatPort_a | port_a | ||
| TAeZoSysPro.FluidDynamics.Interfaces.FlowPort_b | port_b |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| SI.TemperatureDifference | dT | Wall- fluid Temperatures | |
| Medium.Temperature | T_mean | Mean temperature between fluid and wall | |
| SI.CoefficientOfHeatTransfer | h_cv | Heat transfert coefficient | |
| SI.Density | d | Density of fluid at T_mean | |
| SI.SpecificHeatCapacity | cp | Specific heat capacity of fluid at T_mean | |
| SI.DynamicViscosity | mu | Dynamic viscosity of fluid at T_mean | |
| SI.ThermalConductivity | k | Thermal Conductivity of fluid at T_mean | |
| SI.PrandtlNumber | Pr | Prandtl Number | |
| SI.GrashofNumber | Gr | Grashof Number | |
| SI.RayleighNumber | Ra | Rayleigh Number | |
| SI.NusseltNumber | Nu | Nusselt Number | |
| SI.HeatFlowRate | Q_flow | Heat flow rate from wall to fluid | |
| SI.Energy | E | Energy passed throught the component |
Contents
| Name | Description |
|---|---|
 Medium |