Question

Overall heat transfer coefficient formula

Answer 1

The heat transfer coefficient or film coefficient, or film effectiveness, in thermodynamics and in mechanics is the proportionality constant between the heat fluxand the thermodynamic driving force for the flow of heat (i.e., the temperature difference, ΔT):

The overall heat transfer by combined Modes is usually expressed on terms of an overall conductance or overall heat transfer coefficient 'U'.

Heat transfer, Q=UA(T2-T1).


{\displaystyle h={\frac {q}{\Delta T}}}

where:

q: amount of heat transferred (heat flux), W/m2 i.e., thermal power per unit area, q = d{\displaystyle {\dot {Q}}}/dAh: heat transfer coefficient, W/(m2•K)ΔT: difference in temperature between the solid surface and surrounding fluid area, K