Patent Application
20140291991
The present invention is directed to improving the performance of wind turbines and, more particularly, to increasing the electrical output generated by a wind turbine and doing so during low wind speed conditions.
Wind energy is increasingly being considered a viable alternative energy source for providing electrical power. Wind energy is free, plentiful, widely distributed, clean, and does not produce unwanted greenhouse gas emissions. Traditionally, wind energy has been converted to electrical energy by large-scale wind farms in which wind turbines convert the wind energy to electrical energy that is fed to the power grid for subsequent distribution to homes, businesses, municipal facilities, schools, hospitals, and the like increasingly, building owners and homeowners are exploring the use of relatively small-scale wind turbines to, provide off-the-grid electrical energy to individualized buildings, homes, or localized groups of buildings.
One of the drawbacks of localized installation of wind turbines to provide off-the-grid electrical power to a home or other building is the initial capital costs. While many governments, including the United States, offer tax incentives or tax rebates for making, such installations, for many, the equipment, installation, and maintenance costs largely outweigh the per/year return on investment associated with operation of such systems. In an effort to improve the viability of localized wind turbine system as a residential alternative energy source, efforts have been made to improve the operating efficiency of such wind turbines. These efforts have included modifications to the turbine construction and/or shroud or, guide structures that are designed and positioned to redirect and/or amply wind directed toward the blades or vanes of the wind turbine.
It has been largely believed that shrouded wind turbines are better able to convert wind energy to electrical power or energy than un-shrouded wind turbines. In fact, some manufacturers of shrouded wind turbines have suggested that their shrouded systems amplify wind speed by as much as twice the ambient wind speed. Amplifying the wind speed in such a manner would cause the rotor of the wind turbine to rotate when ambient unamplified wind speeds may otherwise be insufficient to do so. Testing of exemplary shrouded wind turbine systems has shown that many of the claims regarding improved turbine operation with wind speed amplification cannot be supported. In one experiment, the power output of one shrouded wind turbine was found to be close to the same as the power output of an un-shrouded wind turbine of similar size. Moreover, one tested shrouded wind turbine was found not to produce a positive energy output until an ambient wind speed reached 16 miles per hour (mph).
One skilled in the art would readily appreciate that requiring an ambient wind speed of 16 mph greatly limits the applicability of such a system. This problem of the prior art is particularly problematic given that, for most of the United States, wind speeds at rooftop elevations commonly average less than 12 miles per hour (mph). The testing described above indicates that, although commercial wind turbines are commonly positioned at substantially higher than rooftop elevations, where, greater wind speeds tend to exist, utilization of such improvements at rooftop elevations would increase the cost associated with the wind turbine and only provide a negligible, it any, power generation benefit.
There is therefore a need for an improved residentially available wind turbine assembly that is operable across a wider range of the wind conditions that commonly occur at elevations substantially lower than commercial wind turbine elevations.
The present invention is directed to a method and apparatus of forming a wind turbine assembly that overcomes one or more of the aforementioned drawbacks. In one aspect, wind speed amplification device is disclosed that includes a cone-shaped structure that is positioned adjacent the intake side of an un-shrouded wind turbine. The cone-shaped structure may be free standing or mounted to the frame, housing, or other structure of the wind turbine. The amplification structure is preferably centered about the hub of the rotor on the intake side of the wind turbine, and is designed to redirect wind away from the center portion of the rotor towards more radially outward located portions of the vanes.
It is appreciated that the cone-shaped structure of the amplification device can be provided in number of different angles, as measured as the angle between the outer conic surface and the imaginary axis extending through the vertex from the base of the cone. In one aspect, the angle of the cone is between 10 and 80 degrees. In a more preferred aspect, the angle is between 30 and 60 degrees. Even more preferably, the angle is 50 degrees.
While the amplification device may be cone-shaped, and centrally positioned relative to the rotational axis of the blades of the turbine, the invention is not so limited. In another aspect of the invention, the amplification device takes the form of a structure that is positioned radially outboard relative to the footprint associated with rotation of the turbine blade. In a preferred aspect, such an amplification device is positioned between adjacent wind turbines and/or at alternate lateral sides of each respective wind turbine. The amplification device redirects wind that would otherwise pass between adjacent turbines toward the cross-sectional area associated with rotation of the blades of the respective wind turbine.
In yet a further embodiment, an amplification system is provided in which a diamond or wedge shaped amplification device is, positioned adjacent the intake side of a wind turbine and an amplification structure is mounted between adjacent wind turbines. In a more preferred embodiment, each wedge shaped amplification device includes a forward facing and reward facing wedge portion that extend upstream and downstream, respectively, relative to the respective wind turbine(s).
Therefore, it is one object of the invention to provide an amplification device for use with a wind turbine.
It is another object of the invention to provide a wind turbine system that is operable at rooftop elevations and at reduced wind speeds.
It is yet a further object of the invention to provide a wind energy system capable of providing a meaningful electrical power output during low wind speed conditions.
The drawings illustrate the best modes presently contemplated of carrying out the invention.
In the drawings:
The present invention is directed to a method and apparatus for improving the performance of wind turbines. While the invention is not limited to any particular implementation, the invention will be described with respect to a rooftop mounted wind turbine that rotates about a horizontal axis. However, as will become apparent from the following description, the invention is not limited for use with a specific wind turbine, and similarly can be used with wind turbines that rotate about a vertical axis at locations commonly associated with inoperability of utility power generating wind turbines. Thus, while the invention will be described with respect to an exemplary gearless blade tip wind turbine 20 manufactured by Honeywell International, Inc, as shown and described with respect to
As shown in
Still referring to
An outer surface 56 of each amplification device 40, 42, 44 extends in a conical shape between base or first end 50 and second or apex end 54. Once oriented relative to wind turbine 20, apex end 54 of each of amplification devices 40, 42, 44 is oriented to be generally aligned with an axis of rotation, indicated by line 60, of plurality of blades 22. The respective amplification device 40, 42, 44 is constructed to be secured to hub 26, frame assembly 32, or independently secured to be positioned forward and concentric relative to hub 26 of the corresponding wind turbine 20 so as to manipulate the cross-sectional footprint associated with directing the wind stream 34 through turbine 20. Although apex end 54 is preferably pointed or substantially pointed, it is appreciated that apex end 54 could be rounded, flat, or have another shape.
A cross sectional shape of each amplification device 40, 42, 44 is shown graphically in
Still referring to
In a preferred embodiment of the invention, amplification device 40 has a base that is 2 feet in diameter, amplification device 42 has a base that is 3 feet in diameter, and amplification device 44 has a base that is 4 feet in diameter when angle 78 is 50 degrees. As further explained below with respect to the first table, it is appreciated that the measure of angle 78 can be manipulated to provide a body of the respective amplification device with other base and geometric height parameters. Regardless of the specific shape of a particular amplification device, each amplification device 40, 42, 44 overlaps a radially center portion of blades 22 thereby directing a portion of the wind flow 34 associated with the amplification device 40, 4144 toward that portion of blades 22 that is not obscured by the respective amplification device 40, 42, 44.
Limiting the portion of blades 22 exposed to wind stream 34 concentrates or amplifies the wind stream associated with operational footprint 70, 72, 74 associated with a respective amplification device 40, 42, 44. Such manipulation of wind stream 34 increases the speed of the wind stream as the wind stream travels from the second or apex end 54 of a respective amplification device toward the respective base or first end 50 of the corresponding amplification device 40, 42, 44. Each amplification devices 40, 42, 44 manipulates the wind speed introduced to a respective turbine 20 to allow utilization of wind turbine 20 to generate electrical energy at ambient wind speed conditions that are substantially lower than ambient wind speed conditions required to effectuate operation of wind turbine 20 without utilization of a respective amplification device 40, 42, 44.
Still referring to
For instance, it is appreciated that angle 78 associated with amplification device 40 can be increased, with or without manipulating the height associated the conical shape, to yield operational cross sections that are between cross sections 70 and 74. Such manipulation would yield an amplification device having an apex that is nearer intake side 52 of wind turbine 20 than, for instance, either of amplification devices 42, 44. Said in another way, the cone shape of any of amplification devices 40, 42, 44 may be constructed such that its size (base radius, r, and cone height, h) as well as the angle 78 between the outer surface 56 of the cone and the vertical axis, h, of the cone provide a desired amplification. The table below shows the results achieved via testing of several conical shaped amplification devices having different angles of cone shape and the resultant percentage of energy increase according to the first embodiment of the present invention attained at wind speeds commonly unsuitable to achieve desired operation of wind turbine 20.
From the data above, it is clear that the wind cone with a 50 degree angle was found to provide the largest power amplification percent at a wind speed of 2.0 m/s. It is understood that the wind cones could be tested under other wind speeds and known statistical analyses could be used to determine the optimal wind cone shape, and size, for a particular wind turbine or common ambient conditions associated with the intended use of the respective turbine 20. It is further appreciated that any of amplification devices 40, 42, 44 can be formed of any material but, due to exposure to atmosphere, each of amplification devices 40, 42, 44 are preferably formed from corrosion resistant material.
System 100 includes one or more wind turbines 20 that each include a plurality of blades 22 that are rotatably supported by hub 26 and disposed radially inward of the outer ring 30. One or more frame members 32 extend between outer ring 30 and hub 26. Each amplification device 102 includes a first deflection wall 104 and the second deflection wall 106 that are shaped to define a first wedge that extends upstream relative to wind stream 34 with respect to the intake side 52 of the respective turbines 20.
Each deflection wall 104, 106 includes a first edge 110, 112 and a second edge 114. First edge 110 of first deflection wall 104 is offset from the first edge 112 associated with second deflection wall 106 such that the first edges 110, 112 define non-common edges of deflection walls 104, 106. Edge 114 is offset forward or upstream from the generally vertical plane 118 associated with system 100 relative to wind flow 34 so as to define a common edge of deflection walls 104, 106. Each amplification device 102 includes a third, deflection wall 120 and a fourth deflection wall 122 that extend in a generally rearward or downstream direction from edges 110, 112 associated with respective deflection walls 104, 106. As such, edges 110, 112 associated with first deflection wall 104 and second deflection wall 106 define non-common edges of third deflection wall 120 and fourth deflection wall 122. Third and fourth deflection walls 120, 122 intersect one another at a common edge 124 that is oriented rearward of plane 118 of turbine 20 and relative to wind flow 34.
Referring to
Still referring to
Like amplification devices 40, 42, 44 shown in
In a preferred embodiment of the invention, amplification devices 102 have a vertical height that approximates the vertical height of a respective turbine 20. In a preferred embodiment, amplification devices 102 are approximately 6 feet tall or generally extend in a vertical direction so as to extend the vertical direction associated with the vertical dimension of the foot print associated with operation of a given turbine. It is further appreciated that such an amplification device can be provided with approximately 8 feet 6 inches between common or apex edges 114, 120 and nearly 4 feet between non-common edges 110, 112. It is appreciated that such dimensions may vary as a function of the size and spacing associated with a respective array of one or more of turbines 20 and/or the dimensions of the respective turbine 20.
It should be appreciated that facility 140 can be configured to benefit from the use of one or any number of turbines 20 and a corresponding number of amplification devices 102. Preferably, the number of amplification devices 102 is at least one greater than the number of turbines 100 associated with the respective system 100 such that each turbine 20 is flanked or otherwise disposed between a pair of adjacent amplification devices 102. It is further appreciated that one or more of turbines 20 can be configured to cooperate with a respective amplification device 40, 42, 44 as well as one or more amplification devices 102. Such a configuration further improves the operational range of a respective wind energy system relative to ambient wind speed conditions and allows utilization of wind, power based electrical power generation at conditions that may not otherwise satisfy the suitable minimum wind speeds associated with operation of unamplified turbine 20.
As evidenced by the data provided above, equipping a wind turbine 20 with one of amplification devices 40, 42, 44 and/or one or more of amplification devices 102 allows utilization of the wind turbine at wind conditions that would otherwise be unsuitable or incapable of generating a desired operation of the wind turbine to generate electrical power. Accordingly, each of amplification devices 40, 42, 44, 102 increases the range of operation of a given wind turbine thereby improving the return on investment associated with utilization of such systems.
Therefore, one, embodiment of the invention includes an apparatus for amplifying a speed of a wind stream directed at a wind turbine that is operable at rooftop elevations. The apparatus includes a body having a first end and a second end wherein the first end is positioned adjacent an intake side of the wind turbine and the second end is displaced upstream relative to a wind direction from the first end. An outer surface of the body is configured to increase the speed of the wind stream that strikes the outer surface as the wind stream travels from the second end toward the first end of the body and redirect the wind steam toward a blade area of the wind turbine.
Another embodiment of the invention that is usable with one or more features of the above embodiment includes a system for generating electrical power from wind energy occurring proximate rooftop elevations. The system includes a first wind turbine and a second wind turbine that each includes a plurality of blades that are independently rotatable relative to the blades of the other wind turbine. The first and second wind turbines are mountable to a building structure such that a space is formed between the first and second wind turbines. A wind speed amplifier is disposed in the space between the first and second wind turbines. The wind speed amplifier has a wedge-shaped cross section relative to a plane that intersects the first and second wind turbines. The wedge-shaped cross section has a base that is nearer the first and second wind turbines and an apex that is offset in a direction of wind flow relative to the first and second wind turbines to amplify wind stream energy directed toward the first and second wind turbines.
Another embodiment of the invention that is usable with one or more features of the above embodiments includes a system for amplifying ambient wind speed communicated to a rooftop elevation wind turbine system. The system includes a wedge having a first deflection wall and a second deflection wall. The first deflection wall and the second deflection wall intersect at a forward common edge. Each of the first deflection wall and the second deflection wall have a non-common edge that is spaced from the non-common edge of the other of the first deflection wall and the second deflection wall such that, when the non-common edge of one of the first deflection wall or the second deflection wall, is positioned adjacent a wind turbine, the forward common edge is spaced radially outward and longitudinally forward of an area of rotation, of a plurality of blades of the wind turbine. The system includes a hub amplifier having a conical shape defined by a base shaped to be disposed adjacent an inlet side of the wind turbine and an apex that is offset longitudinally from the base along an axis of rotation of the plurality of blades of the wind turbine.
Many changes and modifications could be made to the invention without departing from the spirit thereof The scope of these changes will become apparent from the appended claims.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/529,355 filed on Aug. 31, 2011 titled “Method and Apparatus For Amplifying Wind Stream To A Wind Turbine” and the disclosure of which is expressly incorporated herein.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US12/53286 | 8/31/2012 | WO | 00 | 4/3/2014 |
| Number | Date | Country | |
|---|---|---|---|
| 61529355 | Aug 2011 | US |
