.TAeZoSysPro.HeatTransfer.BasesClasses.FreeConvection

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.

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