Environmental Engineering Reference
In-Depth Information
11.2. Capital Equipment Cost
11.2.1. Capital Cost of MED Evaporator
The cost of MED evaporator is based on budget offers from different manufacturers and
on cost information available in the open literature. The capital cost depends on the design
capacity, number of effects and maximum brine temperature according to the correlation
given by Fosselard et al.[6]:
m
PR
70
d
0
0
0
.
47
C
=
5
005
,
000
(
)
(
)
(
)
100
≤
m
≤
1000
(68)
ev
d
2
500
8
T
b
max
where
C
ev
= evaporator capital cost, $
m
d
= rated (design) capacity, m
3
day-1
PR
= performance ratio
T
bmax
= design maximum brine temperature, °C.
The performance ratio (
PR
) of the evaporator (defined as the distillate output in kg per
1055 kJ of heat input) is related to the number of effects by the following equation[1]:
2
PR
=
−
0
809
+
0
932
N
−
0
0091
N
(69)
11.2.2. Capital Cost of Solar Thermal Collectors
Solar collectors used for this application should be capable of producing hot water at a
temperature ranging between 70 and 90°C. Evacuated tube collectors and high-efficiency flat
plate collectors can be used to produce hot water at a temperature in excess of 80°C. The
specific cost of the solar collectors are assumed to range 200 - 600 $ m-2 (flat plate and
evacuated tube collectors). The cost is assumed to include both the solar collector proper as
well as the support structure, piping, valves, etc.
11.2.3. Capital Cost of Heat Accumulator
The heat accumulator is assumed to be a vertical cylindrical tank made of mild steel with
a thick layer of fiberglass insulation to reduce heat loss. The tank is designed to operate at
atmospheric pressure and is provided with a pressure relief valve as a safety measure. Hot
water from the collector field is supplied to the tank at the top via a special water distribution
grid that ensures that hot water diffuses slowly through the surrounding water with causing
too much turbulence in order to enhance thermal stratification through the tank.
The capital cost of the heat accumulator as obtained from manufacturer's data is obtained
from the following relation
0
525
C
=
7803
.
×
m
100
≤
m
st
≤
600
(70)
st
st
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