Environmental Engineering Reference
In-Depth Information
Q
=
M
×
C
×
(
T
(
−
T
)
(22)
ph
fw
p
ph
cond
2
The log-mean temperature difference (Δ
T
)
ph
is assumed to be identical for each preheater.
5.3.5. OHTC of Condenser
The OHTC of the condenser is calculated from the measured seawater flow rate and
condenser inlet and outlet temperatures according to the equation:
Q
cond
U
=
(23)
cond
A
×
(Δ
T
)
cond
cond
where
Q
cond
is condenser heat flow rate, kcal/hr,
A
cond
is the condenser heat transfer area, m
2
(
A
cond
= 35.3 m
2
). The log-mean temperature difference for the condenser is calculated from
the equation:
(
T
(
18
)
T
)
(
T
(
18
)
T
)
−
−
−
(
Δ
T
)
=
ev
cond
1
ev
cond
2
(24)
cond
(
T
(
18
)
−
T
)
ln
ev
cond
1
(
T
(
18
)
−
T
)
ev
cond
2
5.3.6. Evaporator Economy
The performance ratio (
PR
) of the evaporator is calculated as the ratio between the
product flow rate,
M
d
(kg/hr) and the equivalent amount of heating steam to the heater (first
effect):
m
d
PR
=
(25)
(
Q
/
L
)
h
where
Q
h
is amount of heat supplied to the heater (first effect) and
L
is the latent heat of
vaporization (kcal/kg).
6. Weather Condition in Abu Dhabi
For a solar desalination plant, the solar radiation and ambient temperature have a great
effect on the heat collection efficiency of the collectors while the temperature and salinity of
the seawater influence the capacity of the distiller. Consequently, these data which have been
yielded by the research operation constitute valuable basic material for analyzing the
performance of the operation of the plant.The total solar radiation on a horizontal surface for
1985 ( see table 5) came to 1,923,000 kcal/m
2
year which gave a mean daily value of 5,270
kcal/m2 day. When the monthly average total solar radiation an a horizontal surface is
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