Basic constitutive equations

Convection from a fluid to a wall

Heat flows from a fluid to a wall as illustrated to the right: Heat transfer to a wall

The rate of heat flow Q [W] over the area A [m2] and through a laminar film of thickness x [m] may be written as:
Convection to a wall
where λ [W/m·K] is the wall thermal conductivity.

Since the thickness of the film is unknown and almost impossible to estimate this equation is usually rewritten as:
Convection to a wall, rewritten
where λ is called the individual heat transfer coefficient [W/m2·K].

In English literature the heat transfer coefficient is normally denoted h [Btu/hr·ft2·°F].



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