## Achieve More Than 85% Efficiency Windmill

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Broad specifications for the proposed windmill are listed below..

• Windmill must have minimum of moving parts and light in weight to orient itself to face the wind.
• Wind flow escaping between blades is almost eliminated.
• We must avoid using brushes anywhere in the chain to tap electrical energy.
• To obtain highest tip speed one could consider using a conveyor design instead of a rotating wheel- be it horizontal or vertical axis.
• Hence use two generators of half capacity instead of one at the center.
• Betz’s formula only states that highest energy is extracted when incoming wind to out going wind speed ratio is 1/3.
• Let us say wind has a velocity of Vin. Then as per formula for power from the wind is Pin = ½* ?*A*(Vin^3), where ? = density of wind in (Kg/ meter ^3), A = Area of wind captured in meter^2, Vin = velocity of wind in m/ sec. http://en.wikipedia.org/wiki/Wind_power#mw-navigation />• Betz’s law http://en.wikipedia.org/wiki/Betz'_law#mw-navigation />o Interpretation of BETZ’s law.
• Design blades in such a manner that wind speed leaving the blade is about 1/3 incoming wind speed. It looks this is the real trick.
• Hence power in the incoming wind is Pin = ½* ?*A*(Vin^3) and residual power in the outgoing wind is Pout = ½* ?*A*(Vout^3) = (1/27)*½* ?*A*(Vin^3). Hence energy which can be extracted is Pin-Pout = (26/27)* ½* ?*A*(Vin^3) = 96.29% of the energy in the incoming wind

CONVEYOR TYPE WINDMILL.

• It is well known in defense that battle tanks have conveyor to simulate almost infinite radius and hence this approach is being adopted.
• Further to extract energy in a brushless manner – the wind is being captured in an omni directional manner – and converted to uni-directional wind always.
• Further to avoid wind escaping without any energy being extracted – additional passive radar / wind blocker is proposed.

Blade design requirements are as follows.
• In-coming wind speed must drop down to 1/3 as wind leaves the blade.
• This means area of wind captured must be = 1/3 of area at out going point.
• Hence to avoid confusion of area facing the wind and area at out going end- it must preferably in orthogonally perpendicular plains.

• To avoid build up of wind pressure, the area of the conveyor facing the wind= area of the wind captured perpendicular to it.
• Wind flow in horizontal plain is turned to vertical plain towards the conveyor.
• Conveyor will always move in same direction irrespective of wind flow direction.
• Wind blocking segment ensures wind will not escape in horizontal plain straight away.
• Note forces generated on every blade of conveyor is always aiding smooth movement always in one direction – both at upper belt side and lower belt side. This is not so with any rotating wheel- whether it is vertical axis or horizontal axis.

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• Name:
Mohan Divekar
• Type of entry:
individual
• Number of times previously entering contest:
2
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