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

compounds, and the usable temperature ranges generally limit Ste to ζ (10 −2 ).
However, the practical average yearly limit of Ste is ζ (1) for the present case, which
means that with this larger value of Ste the amount of sensible heat is much higher
than the latent heat.
8.3.7 Effect of PCM melting temperature (T m )
For examining the effect of different melting points, the specific heat capacities (i.e.
solid, liquid and apparent heat capacity) of all simulated PCM candidates are
assumed to be equal and the same as the PCM A-70. Only the melting point of the
PCM was changed individually. Thus, the influence of the melting temperature shall
become evident even if a PCM with these characteristics does not exist in reality.
Figure (8.12) shows the
effect of T m on the plant
hourly distillate rate for
both Al-Arish and Al-
Kharga locations at two
different collector areas.
For low and high values of
T m =40 and 80°C, the
distillate rate is higher than
the intermediate melting
points. As the T m at
intermediate points of 50,
60, and 70°C becomes
more closer to the inlet hot
water temperature, the
distillate rate is reduced.
When T m becomes
sufficiently lower than the
inlet hot water temperature
to the store, i.e. at
T m =40°C, it represents a
mostly latent heat storage
in the response since most
Figure 8.12: Effect PCM melting temperature in
the external thermal buffer
of the PCM layers will be in a molten state for many hours a day. This implies that
the thermal storage will behave as a sensible storage during these molten hours and
the storage axial temperature profile will become more homogeneous (i.e. less
stratified). Thus, the outlet fluid temperature gets better as one gets away from
discontinuity in the storage temperature.
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