Experimental and Numerical Analysis of a PCM-Supported ...

latent heat transfer over the influence of MEHH. In this case we can see that
Hiflow packing produces 36% more distillate than the PCM packing, while the
specific surface area of Hi-Flow Rings is 600% that of the PCM spheres. At
higher air velocities and high wetted area, direct heat and mass transfer between
water and gas dominates, which reduces the energy flow from water to the PCM
beads. Thus results in damping the MEHH over the packing height.
It can be easily seen from the second, third, and fourth cases that lowering water
mass flow rate and/or air mass flow rate has an influence on decreasing the
direct contact heat and mass transport, and thus gives rise to the MEHH through
the liquid-sloid-gas parallel heat path accompanied by thermal stratification in the
bed. In the third case, which is already more interesting from the previous
section, the MEHH influence is more pronounced here and this is clear from the
fact that empty spheres produce almost the same distillate as Hiflow Rings and
the productivity of both of them is 16% lower than that of the PCM packing.
Figure 5.11: Comparative productivities for PCM, Empty spheres,
and Hiflow rings packing media for 0.38m packing height (for two
hours of steady state operation)
The last two cases under natural convection (V.C.), reveal that the influence of
MEHH increases under the high input energy to the system (m hw =500 l/h and
T w1 =83°C) resulting in a higher production of 13% more than that of the Hi-flow
Rings in the last case. Under natural convection where air flow is induced by the
double diffusion effects (density and humidity gradients), the MEHH boosts the
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