Heat transfer

Heat transfer

Heat transfer is called the transfer of heat from one fluid through a wall to another fluid. It consists of three processes:

• Heat transfer from fluid 1 to the surface of the wall

• Heat conduction through the wall

• Heat transfer from the surface of the wall to fluid 2

The heat flux density through a wall of the surface is calculated using the heat transfer coefficient (also called U in construction ) ${\displaystyle \textstyle {\dot {q}}}$ ${\displaystyle \textstyle A}$ ${\displaystyle k}$

${\displaystyle {\dot {q}}=k\cdot \Delta T}$,

where denotes the temperature difference between the two fluids at a sufficient distance from the wall. The heat transfer coefficient depends on the one hand on the geometry and the thermal conductivity of the wall. On the other hand, it also depends on the two heat transfer coefficients between the fluids and the wall, which in turn depend on the flow field (expressed by the Reynolds number ) and the physical properties of the fluids ( Prandtl number ) and can be calculated using Nusselt functions . ${\displaystyle \textstyle \Delta T}$

See also

• Thermal conductivity
• Thermal resistance

• Thermal boundary layer