Film Temperature

 , where:

Tf = Film Temperature (K)

Ts = Surface Temperature (K)

 = Surrounding Temperature (K)

Fin Efficiency Equation

The efficiency of a fin, which should not be confused with the fin effectiveness, is defined and can be graphed as:

 , where:

 = Fin Efficiency (%)

hf = Convection Coefficient of Fin (W/(m2*K))

k = Thermal Conductivity of Fin (W/(m*K))

tf = Thickness of Fin (m)

Grashof Number

 , where:

Gr = Grashof Number

g = Gravity (m/s2)

 = Coefficient of Thermal Expansion (1/K)

Ts = Surface Temperature (K)

 = Bulk Temperature (K)

Heat loss through a heat sink

 , where:

 = Rate of Heat Lost (W)

Ths = Temperature at base of heat sink (K)

Rhs = Thermal Resistance of Heat Sink (K/W)

Heat Transfer Coefficient

 , where:

h = Heat Transfer Coefficient (W/(m2*K))

q = Flow of Heat (W)

A = Cross-Sectional Area (m2)

T = Difference in temperature (K)