Heat Transfer-1 (color)

• Regardless of the flow phenomenon involved, it is known that
directly adjacent to the interface, the energy transfer mechanism is
that of conduction. The surface conductive layers of fluid control
the heat transfer rate and determine the value of “h”, which is
justifiably often called the “film coefficient”. The only difficulty in
describing convective phenomena lies in the evaluation of “h”.
• If we write : q = KΔT where K is the thermal conductance.
K convection = hA
K conduction hollow cylinder =
K conduction plane wall = kA
L
2 kL
ln r ⎫
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⎬ Btu / hr.°F
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