Environmental Engineering Reference
In-Depth Information
Influence of the Water Feed Flow Rate
Just after its inlet in the cavity, the water is successively heated then evaporated. Both
operations depend on the mean velocity of the falling film along the heated wall which
depends on the water feed flow rate. This parameter thus influences the behavior of the
distillation cell. Figure (3-b) shows that the yield decreases when the water feed flow rate
increases. The energy aspect appears on figure (3-a) where it can be observed, that when the
water feed flow rate increases:
•
The sensitive heat flux density evacuated by the brine increases, as the outlet flow
rate
m
out
increases influencing
q
out
according to Equation (3).
•
The latent heat flux density decreases
q
l
as a consequence of the increase of
q
out
.
a
b
Figure 5. Influence of the feed flow rate on the exchanged fluxes (a) and on the yield (b).
(q
f
=
900W/m², T
c
= 23.7 °C, T
feed
= 25°C).
The best yield is obtained at low values of the feed flow rate. However, in real operating
conditions, imposing very low feed flow rates presents the risk of provoking a drying along
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