
344 Heat Transfer: Thermal Management of Electronics
where
is the radiation heat transfer rate from a U-shaped channel, N
f
is the num-
ber of ns, σ is the Stefan–Boltzmann constant, ε is the surface emissivity, and t, t
b
,
H, L, W, and S are heat sink dimensions as shown in Figure 13.16. Rea and West [6]
and Bilitzky [7] dened “apparent” or “effective” channel emittance,
, such that the
channel radiation heat transfer rate can be calculated as
QSLT T
ch rs,
ˆ
().=−εσ
44
surr
(13.78)
The effective emittance accounts for emission as well as reection from the plate
ns. Since channel base area rather than the whole channel area is used in ...