The relationship between two-phase friction and Reynolds
number in the HFMs, and the C-value in the SFMs indicates
that the flow pattern is strongly related to the two-phase
frictional pressure drop in the rectangular microchannels.
In addition, the flow patterns in the rectangular microchannel
are different from existing patterns. Therefore, correlations
based on the flow pattern were proposed for both
HFM and SFM. The new HFM based on flow pattern is developed
from Beattie and Whalley (1982)’s viscosity model, and
is improved to its MAE of 13.21%. The new SFM based on the
flow pattern was developed by modifying Qu and Mudawar
(2003)’s correlation, and decreased its MAE of 11.13%. In
both new correlations, a dependency on a channel diameter
was observed only in the liquid ring flow regime. This could
be due to the different ARs of the rectangular cross-sections.
To achieve more accurate correlations for rectangular microchannels,
studies of the effects of both diameter and AR on
the pressure drop in microchannels are necessary