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Field Experiments. References: Liu, C.C.K., Park, J.W., Migita, R. and Qing, G. (2002). Prototype Experiments of a Wind-Driven Reverse Osmosis Desalination System, Journal of Desalination , Vol. 150, No. 3, pp. 277-287. Energy conversion Efficiency. Wind-powered Two-stage Pumping. - PowerPoint PPT Presentation
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Field Experiments
References: Liu, C.C.K., Park, J.W., Migita, R. and Qing, G. (2002). Prototype Experiments of a Wind-Driven Reverse Osmosis Desalination System, Journal of Desalination, Vol. 150, No. 3, pp. 277-287.
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0.1
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2 3 4 5 6 7 8 9 10
Wind speed, m/s
Energy conversion Efficiency
99.189.1)438.0exp(73.0 UU
Wind-powered Two-stage Pumping
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20
40
60
80
100
120
12:14:24 12:57:36 13:40:48 14:24:00 15:07:12
Time
Pre
ssu
re, p
si
Field experiments on System Operation Under Varying Wind Speed
500
600
700
Pres
sure
, kPa
Time, hrs
Win
d s
pe
ed
, m
/sO
pe
rati
ng
pre
ss
ure
, k
Pa
Reverse osmosis sub-system
Water flux
)}(779.0{ pfw CCpkJ
Salt flux
)( pfii CCkJ
kw and ki = coefficient for water and salt flux, respectivelyp = imposed pressure gradient (kPa)Cf = TDS concentration of the feed water on RO membraneCp = TDS concentration of the product water.
Concentration of the feed water as it flows over the RO membrane
Cfn
Qfn
Cbn
Qbn
Cn, p
Cpn, Qp
n
dA, k, kNaCl
membrane
nth control volumen-1th n+1th
Cfn
Qfn
Cbn
Qbn
Cn, p
Cpn, Qp
n
dA, k, kNaCl
membrane
nth control volumen-1th n+1th
)(0779.0 np
nfw
np CCpdAkQ
dAkQ
dACkC
inp
nfin
p
System simulation: Feed water flow and pressure
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7
2 3 4 5 6 7 8 9 100
0.5
1
1.5
Pum
ping
rat
e, g
pm
Wind speed, m/s
100 psi (690 kPa)
80 psi (552 kPa)
60 psi (414 kPa)
Pum
ping
rat
e, m
3 /hr
120 psi (827 kPa)
Wind speed, m/s
Pu
mp
ing
rat
e, g
pm
Pu
mp
ing
rat
e, m
3 /h
r
System Optimization
Maximize the rate of permeate flow Qp = f (p, Cf, U, and membrane area)
Constraints414 p 965 kPa (60 p 140 psi) (1)
Qb / Qp ≥ 5 (at any element) (2)
Cp 400 ppm (3)
Qf 6 gpm (1.4 m3/h) for 2540, 16 gpm (3.6 m3/h) for 4040 (4)
Objective function
Reference: Park, S. and Liu, C.C.K. (2003). Experiment and Simulation of a Wind-driven Reverse Osmosis Desalination System, Water Engineering Research, Vol.4, No.1, pp. 1-17.
Effective RO membrane area of available RO configuration types
TypeRO Membrane Configuration
Effective areaMaximum recovery rate
A 2540 1 2.32 m2 (25 ft2) 15 %
B 2540 2 4.65 m2 (50 ft2) 25 %
C 2540 3 6.97 m2 (75 ft2) 35 %
D 4040 1 7.43 m2 (80 ft2) 15 %
E 4040 1 + 2540 1 9.75 m2 (105 ft2) 20 %
F 4040 2 14.9 m2 (160 ft2) 25 %
System design guide
Input:a. Wind speedb. Feed water salinity
System parameters:a. Membrane configurationb. Operating pressure (kPa)
Output:a. Permeate flow rate (m3/hr)b. Permeate salinity (ppm)
System optimization and design/operation guide
14-foot WindmillFeed Water Concentration (TDS, ppm)
1000 2000 3000 4000 5000
AveragedWindSpeed(m/s)
2
C1 4142 C 483 C 483 A 621
0.103 834 0.10 179 0.07 322 0.03 318
3C 552 C 621 C 621 C 690 B 758
0.15 61 0.14 129 0.11 222 0.11 315 0.07 372
4F 414 F 414 F 483 C 827 C 896
0.22 80 0.17 195 0.16 308 0.15 245 0.14 324
5F 414 F 483 F 552 C 896 C 965
0.22 77 0.21 162 0.20 258 0.17 215 0.16 283
6F 483 F 483 F 552 F 621 C 965
0.27 67 0.22 158 0.21 250 0.20 351 0.16 269
7F 483 F 552 F 552 F 621 C 965
0.27 66 0.26 138 0.21 246 0.20 344 0.17 261
8F 483 F 552 F 621 F 621 C 965
0.27 65 0.26 137 0.25 216 0.20 340 0.17 257
9F 483 F 552 F 621 F 758 C 965
0.27 65 0.26 136 0.25 214 0.24 301 0.17 255
Pilot Plant Design
Cost Analysis for a Scaling-up System with 50 20-ft Windmills
Cost Analysis for one single unit
Capital cost: $45364.00Capital recovery factor: 0.0736 (20 year project period at 4% interest)Annual operational cost: $4330.00Total annual costs: $6968.00
Total freshwater produced: 1,285,000 gallons
Freshwater Production Cost: $5.40 per 1,000 gallon
Technological Transfer Wind-powered RO Desalination Station on Penghu, Taiwan
1. Water and energy are critical natural resources and are inextricably linked.
2. Conventional water desalination processes are energy intensive and cannot be adopted by coastal and other similar remote communities where both freshwater and electric power are in short supply.
3. A renewable-energy--driven reverse osmosis system was designed and successfully tested at a pilot experimental site on Coconut Island, Hawaii.
4. A design guide for the system used for brackish water desalination was prepared based on mathematical simulation and optimization.
5. A pilot plant with 50 windmill units was designed and analyzed. This pilot plant can produce a freshwater of 0.20 million gallons per year per unit at a cost of $5.40 per 1,000 gallons.
IV. Concluding Remarks
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