Icing and Mitigation of wind turbine

1. ICING AND ICING MITIGATION OF
WIND TURBINE
PRESENTED BY: GUIDED BY:
ABOOBACKER MT NISAR O
CEANEME003 ASSISTANT PROFESSOR
S8 ME1 MECHANICAL DEPT.
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2. CONTENTS
• Introduction
• Icing of wind turbine
• Ice formation
• Type of icing
• Effect of icing
• Icing mitigation system
• Conclusion
• References
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3. INTRODUCTION
• Wind energy, mainly applied for electricity generation
using wind turbine
• There are two important issues related to wind turbine
performance in offshore site
• That located in cold region and presence of
atmospheric icing
• Atmospheric icing due to water condensed in
atmosphere
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4. ICING OF WIND TURBINE
• The phenomena of icing means climates exposed to
freezing temperature
• As the wind energy project continue to be developed
in these region
• Surface of wind turbine blade are inevitably exposed
to icing
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6. ICING FORMATION DEPENDS ON
• Air temperature
• Relative humidity
• Wind speed
• Air density
• Altitude
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7. TYPE OF ICING
1. In-cloud icing
2. Precipitation
3. Frost
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8. 1.IN-CLOUD ICING
• It happens when super cooled water droplets hit a
surface below 0 °C and freeze upon impact.
• The droplets temperature can be as low as −30 °C and
they do not freeze in the air, because of their size.
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9. TYPE OF IN-CLOUD ICING
• Soft rime
• Hard rime
• Glaze
• Wet snow
• Freezing rain
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10. RIME ICE GLAZE ICE
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11. 2. PRECIPITATION
• It can be snow or rain.
• The accretion rate can be much higher than in-cloud,
which causes more damage.
3. FROST
• It also called hoarfrost
• It forms when the temperature of the surface is lower
than the dew point of the air.
• This causes water vapour to deposit on the surface
forming small ice crystals
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12. EFFECT OF ICING
• Aerodynamic effects
• Mass imbalance
• Power losses
• Safety risk
• Effects on instrumentation and controls.
• Measurement errors
• Mechanical failures
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13. AERODYNAMIC EFFECT
• The build-up of ice on the wind turbine blades
disturbs the aerodynamics which decreases the power
production
• For severe icing, it may not be possible to start the
turbine with subsequent loss of all possible power
production.
• Even for slight icing, the roughness due to ice
adhesion may also alter the aerodynamics and
therefore leads to power loss.
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14. MASS IMBALANCE
• The added ice mass increases the loads on all turbine
components.
• Asymmetric masses cause a mass imbalance between
blades, which might reduce the turbine lifetime
significantly.
• Blade mass imbalance induces rotor mass imbalance
and leads to vibrations of rotating shaft
• Resonance may occur due to change of natural
frequencies of the blades.
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15. POWER LOSSES
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16. ICING MITIGATION SYSTEM
• Icing mitigation system have two process
1. ANTI-ICING: To prevent ice to accrete on object
2. DE-ICING: It is the process of removing the ice
layer from the surface
• The both strategies can divided into two method:
passive and active
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17. PASSIVE ANTI-ICING SYSTEM
1. SPECIAL COATING:
• Ice-phobic coatings prevent ice from sticking to the
surface because of their anti-adherent property.
• While super-hydrophobic coatings do not allow water
to remain on the surface because of repulsive features
2. BLACK PAINT:
• Black paint allows blade heating during daylight and
is used with an ice-phobic coating.
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18. 3.CHEMICALS:
• When applied on blade surface, chemicals lower the
water's freezing.
DISADVANTAGES:
• It is a pollutant
• It needs special maintenance.
• It cannot remain on the surface of the blade for a long
period.
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19. PASSIVE DE-ICING SYSTEM
1. FLEXIBLE BLADES:
• Flexible blades are flexible enough to crack the ice
loose.
• Blade flexing is known to help shed the ice.
2. ACTIVE PITCHING:
• Semi-active methods use start/stop cycles to
orient iced blades into the sun.
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20. ACTIVE ANTI-ICING SYSTEM
1. THERMAL:
• Heating resistance and warm air can be used in anti-
icing mode to prevent icing..
ADVANTAGES:
• No ice accumulates on blades.
• Blade can be kept at−5 °C, instead of 0 °C, in good
condition.
DISADVANTAGES:
• It needs a lot of energy
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21. 2. AIR LAYER
• Air layer consist in an air flow
• It originating inside the blade
• The air is pushed through rows of small holes near
the blades
• To prevent the ice formation
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22. 3. MICROWAVE
• It consists of heating the blade's material with
microwaves to prevent ice formation.
• The objective is to maintain the blade surface
at a temperature slightly above 0 °C, it save
some energy
• It is recommended to cover the surface of the
blade with a material that reflects microwaves
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23. ACTIVE DE-ICING SYSTEM
1. HEATING RESISTANCE:
• It consists of electrical heating element embedded
inside the membrane or laminated on the surface.
• The idea is to create a water film between the ice and
the surface.
• Electrically heated foils can be heating wires or
carbon fibres.Heating elements cover the leading
edge area of the blade.
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24. 2. WARM AIR AND RADIATOR:
• It consists of blowing warm air into the rotor blade
at standstill with special tubes.
• Blowers located in the root of each blade or inside the
hub produce the hot air.
• The heat is transferred through the blade shell in
order to keep the blade free of ice.
DISADVANTAGES:
• This method consumes lot of power
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25. CONCLUSION
• Icing of wind turbines is by no means trivial.
• It is necessary to understand how icing occurs, and
the effects of icing.
• There are two reasons.
• One is based on the model for icing and other is that
the blade tips can experience icing due to low clouds.
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26. REFERENCES
• 1) Jasinski, W.J., Noe, S.C., Selig, M.S. and Bragg,
M.B, “Wind Turbine Performance under Icing
Conditions, Aerospace Sciences Meeting & Exhibit”.
AIAA, 1997, pp. 8.
• 2) Makkonen, L. and Autti, M, “The Effects of Icing
on Wind Turbines”, EWEC, 1991, pp. 575-580
• 3) Battisti, L., Baggio, P. and Fedrizzi, R, “Warm-Air
Intermittent De-Icing System for Wind Turbines”,
Wind Engineering, 2006, pp. 361-374
• 4) Tammelin, B, “Wind Energy Production in Cold
Climate” (WECO),2000
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27. THANK YOU
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