radiation-cooled dew water condensers studied by computational fluid dynamic (cfd) owen clus
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Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Owen CLUS
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
2006 European PHOENICS User meeting
Wimbledon, 30th Nov. 1st Dec., 2006Radiation-cooled Dew Water
Condensers Studied by Computational Fluid Dynamic
(CFD) Owen CLUS
Jalil OUAZZANI Marc MUSELLI
Vadim NIKOLAYEV Girja
SHARANDaniel BEYSENS
Université de CorseArcofluidUniversité de CorseCEA/CNRS-ESPCI Paris Indian Inst. of Management, Ahmedabad CEA/CNRS-ESPCI Paris
International Organization For Dew Utilization International Organization For Dew Utilization
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Atmospheric vapour harvesting by radiative cooling
Researches for condensing atmospheric vapor as alternative water resource in arid
areas without energy supplying
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Atmospheric vapour harvesting by radiative cooling
Researches for condensing atmospheric vapor as alternative water resource without
energy supplyingRadiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
ROOF
CLEAR SKY
GROUND
substrate
Insulation
Radiative budget - 70 W/m²
Surface 3 to 8°C below Tambient
Innovative formulations cheap polymers
LDPE, paint high IR emissivity
polymerbasis
Radiative Filler
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Pilots, Prototypes
1 m²
Dew = 30 % of rain
Quantitativesystems
15 m² 7 L / night
800 m² 300 L/ night
Experimental prototypes
30 m² 10 L / night1 m² 0.6 L / night
FRANCE FRANCE
CROATIA
INDIA
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
CFD simulations of radiative condensers
The CFD tool has been developed for helping decision and technical choices before
implementing these huge systems without preliminary empirical tests
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Radiative condenser as thermal machine
Wind flow
condensation in weak wind, limit free / forced convection
variability of meteorological data induces long time outdoor experiments
no description for complex shapes without empirical corrections
α
r R
Condenser shape and thermal properties
Free convection heating
Radiative cooling
forced convection heating
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Radiative cooling inclusion in CFD
cos
1
, 11 bss
dR = (εs,θ σTamb4 – εr σTrad
4) dΩ
εr = 0.94
α
θ
1
0.94 dΩSKY
εm
εs,θ
α
θ
1
0.94 dΩSKY
εm
εs,θ
Specific radiative cooling for each shape
angular sky emissivity
isotropic radiator emissivity
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Radiative cooling inclusion in CFD
FORTRAN tool for integrating radiative budget on various shapes
angular integration
dissipation law included in Phoenics computation: ER = f(T)
-80
-70
-60
-50
-40
-30
-20
-10
0
5 10 15 20
BILANS RADIADIFS (en ciel nocturne clair à 15°C)
plan 0.0°
plan 30°
cone 20°
cone 30°
cone 40°
Pui
ssan
ce d
issi
pée
(W/m
²)
Température Foil (°C)Radiator Temp. (°C)
Rad
iati
ve b
ud
get
(W/m
²)
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Radiative condenser described in CFD
3 Dimensions virtual reality description
Shape Materials
LOG Wind Profile
Convective
heating
Radiative cooling
Radiative cooling power ER is dissipated for each radiator cell. TRAD (one phase model as in dry air)
GridVolumes
Convective heating for every shapes and for various wind speeds is given by Iterative calculation
P T ρ
u v w
ER
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Cone-shaped condenser simulation
Wind speed variations for 0.25 ; 0.5 ; 1.0 and 2.0 m/s at 10 m
WIND PROFILE
side tilt variations for 50 ; 40 ; 35 ; 30 ; and 25 Deg.
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Cone-shaped condenser simulation
30° tiltedMore efficient
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Cone-shaped condenser prototype (France)
30° tilted
7.3 m², Φ 3 m
3.160 L water / night
38 % more water than on the 1m² planar condenser
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
CFD simulations validation
Comparison of simulated efficiency with physical measurements on real system on 5 various condensers from 0.16 to 255 m² installed during long period
1 m² planar condenser is the reference because always set up simultaneously nearby each system
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Radiative condenser as thermal machine
(B)(A)
0.16 m²
(D)
30 m²
(C)
7.3 m²
(E)
3 ridges 255 m²
1 m² REF
(B)
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Comparison “Temperature gain” / “Dew gain”
Non quantitative comparison, the cooler the surface, the better
the dew yield.
Surface Temperature TCOND,
Simulations rough results
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Comparison “Temperature gain” / “Dew gain”
“Dew gain” related to 1 m² REF condenser water volume.
“Cooling power” or “temperature gain” related with Ta and 1 m² REF:
af
acond
TT
TTT
Re
0
REF
COND
H
HH 0
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Comparison “Temperature gain” / “Dew gain”
“Dew gain” related to 1 m² REF condenser water volume.
“Cooling power” or “temperature gain” related with Ta and 1 m² REF:
af
acond
TT
TTT
Re
0
REF
COND
H
HmmH )(
Radiation-cooled Dew Water Condensers Studied by Computational
Fluid Dynamic (CFD)
Comparison “Temperature gain” / “Dew gain”
“Dew gain” related to 1 m² REF condenser water volume.
“Cooling power” or “temperature gain” related with Ta and 1 m² REF:
af
acond
TT
TTT
Re
0
REF
COND
H
HmmH )(
Conclusion
INDIA
Little set of data is needed to conclude the validation of the program
This program has been advantageously used in Dew factory project for orientation and yields prospective
Next step is to develop a two phases dew condensation simulation for more accurate quantitative results
Radiation-cooled Dew Water Condensers Studied by Computational Fluid Dynamic
(CFD)
Owen CLUS
CONTACT : http://www.opur.u-bordeaux.fr/