3. Data reduction
Due to the cover plate, which was made of polycarbonate, an
adiabatic fin tip was assumed to obtain the wall heat flux, qw, calculated
based on the effective area, given by
qw ¼
qbðWch þWf Þ
ðWch þ 2gHf Þ
ð1Þ
where Wch, Wf, Hf and g represent, respectively, channel width, fin
thickness, channel depth and fin efficiency. qb, which is the heat flux
from the heater to the working fluid, was obtained from a steadyflow
thermal energy equation with no changes in latent energy.
The average heat transfer coefficient is given by
For one dimensional heat conduction with adiabatic fin tip, the
fin efficiency is expressed by
g ¼
tanhðmHf Þ
mHf
ð3Þ
where m is defined as
m2 ¼
hP
kAc
ð4Þ
In Eq. (4), P stands for fin perimeter, k for thermal conductivity
and Ac for fin cross-sectional area.
As suggested by Park and Thome [23], an iteration process for
Eqs. (1)–(4) was needed to determine the wall heat flux and heat
transfer coefficient. The process was carried out until the fin efficiency
converged to a fixed value.