Dew condensation: effect on dust deposition rate

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Dew condensationeffect on dust deposition rate

• S.A. Biryukov1 and L.I.Yarmolinsky2
• 1-The Jacob Blaustein Institutes for Desert
  research, Department of Solar Energy and
  Environmental Physics. Ben-Gurion University of
  the Negev, Sde Boqer Campus, 84990, Israel
• 2-The Jacob Blaustein Institutes for Desert
  research, Albert Katz International School for
  Desert Studies. Ben-Gurion University of the
  Negev, Sde Boqer Campus, 84990, Israel

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Cleaning Solar collectors from the dust needs
spending much water and manpower
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Solar Power Production in Desert Area

• Aim
• Laboratory study of dew condensation influence
  on the process of dust deposition

Positive factor High level of solar radiation.
Negative factors
High dust concentration in the air.
The large difference between night and day
temperatures causes dew condensation on solar
collectors
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Methodology
Environmental dust was spread in a deposition
chamber and deposited on two horizontal samples
(glass slides).
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One of the slides was preliminarily cooled down
to the temperature lower than the dew point. The
second (reference) sample was kept at the room
temperature, which was much higher than the dew
point (typically, about 25 C).
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• 1- Dust deposition on the top surface of the slide

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• 2 - Dust deposition on the bottom surface

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• 2 - Dust deposition on the bottom surface

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After the exposure the particle size
distributions on surfaces were measured by
computerised microscope
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TOP SURFACE

• Dust deposition on reference
• slide.

• Dust deposition during water
• condensation on cool slide

Deposition rates were compared for all samples.
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Results (top slide)
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Results (top slide)
N wet reference / N dry reference
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Results (bottom slide)
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Discussion and conclusions
1. Gravity and convection
2. Combined Thermophoresis and
Diffusiophoresis (Stefan flow)
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Discussion and conclusions

• 1. Experiment demonstrated strong
• enhancement of dust deposition
• under conditions of water
• condensation on the cold surface
• 2. This enhancement is much higher
• than the effective enhancement,
• caused by reduced particles
• rebound from wetted surface

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Discussion and conclusions
3. Experiments revealed different dependence
of this enhancement on particle size for the
top and the bottom surfaces
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Discussion and conclusions
4. The additional enhancement for small particles
deposition on the top surface may be related to
supersaturated conditions in pre-surface
interface, which result in condensation of water
on dust particles and their growth.
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