From the above review of the literature, the characteristics of
flow boiling heat transfer in small channels are not entirely consistent
with those in ordinarily sized channel. Moreover, there is
inconsistency in the micro-scale heat transfer results obtained
from different researchers and, as a result, the major heat transfer
mechanisms behind the phase-change phenomena are still unclear
for small flow passages. Flow patterns have been expected to affect
the heat transfer phenomena. Different flow patterns may give differences
in flow boiling mechanisms. The current work is, therefore,
aimed at examining the three-zone flow boiling model for
various flow patterns observed in R-134a refrigerant flow boiling
through a 1.75 mm tube.