Patent ID: 12203450

DETAILED DESCRIPTION

FIG.1illustrates a graph showing the thermal losses along the radius of a conventional wind turbine blade for a plurality of temperature increases. Therefore, it can be seen how the heat flux demand and hence in turn the exact heat flux that should be generated ideally varies gradually as the radius of the blade increases.

Additionally, the heat flux demand increases gradually from the trailing edge until the leading edge (not shown) and further, it may be found that the surface to be heated covers the leading edge until a certain distance towards the trailing edge, and the distance may not be constant along the blade.

Thus, it is illustrated the significance importance of optimizing the heat flux generated along each single section of the radius of the blade and along its chord in each single section of the blade to reduce the energy consumption for de-icing and anti-icing.

FIG.2aillustrates a schematic view of a first preferred configuration clearly showing a wind turbine blade comprising a blade root (1), a blade tip (2), a leading edge (3), a trailing edge (4).

FIG.2aalso illustrates that the wind turbine blade comprises a plurality of heating unit (5) comprising two terminals (6), adapted to be fed by an electric heating current by a conductor (C) and wherein each heating unit (5) is disposed along the longitudinal direction, between the blade root (1) and the blade tip (2) and between the leading edge (3) and the trailing edge (4),

Additionally,FIG.2aillustrates that each heating unit (5) comprises a plurality of heating elements (7).

FIG.2billustrates a schematic view of a second preferred configuration clearly showing that the wind turbine blade comprises a single heating unit (5) extended until the blade tip (2).

FIG.3illustrates a detailed schematic view of a first preferred embodiment of a single heating unit (5) according to the first configuration described above. This is with a plurality of heating units (5) along the blade.

FIG.3clearly shows a single heating unit (5) comprising six heating elements (7) arranged both in parallel and in series in a matrix configuration by string overlaps (9) between adjacent heating elements (7) connected in series and by cross-adjoining junctions (8) between adjacent heating elements (7) connected in parallel.

The heating unit (5) described inFIG.3, is able to change the electric heating current flow (I) without including extra terminal cables. This is a significant advantage as every terminal cable should be connected to a conductor located at inner surface of the blade, which causes great inconvenience for assembly the heating system to a wind turbine blade.

Additionally, by changing the resistance of each heating element (7) the heating unit (4) is further able to generate accurately an increasing heat flux from the blade root (1) towards the blade tip (2) and from the trailing edge (4) towards the leading edge (3) through each heating unit (5). That is, along the longitudinal direction of blade and along the chord.

In a first embodiment shown inFIG.3, this is achieved by changing the material and/or the geometry of heating element (5) and therefore modifying its resistivity and as a consequence its resistance.

In a first embodiment heating elements E1and E3are made of the same material, likewise are E4and E6, but of different materials between each group thereof. Heating elements E2and E5comprise each else another different material. Therefore, linear resistivity and hence resistance is changed and optimized according to desired heat flux at a precise radius and chord portion of the blade.

Additionally, the width of the elements is also varied, in particular the width of elements E2and E5is reduced in relation to the width of elements E1, E3, E4and E6. Again, with the object of optimizing the required heat flux demand at each precise portion of the blade.

Note, that optimizing the resistance of every individual heating element (7) according to the specific configuration, the heating flux can be accurately optimized through every single heat unit (5) and as a consequence more accurately optimized along the longitudinal and cross-sectional direction of the blade.

FIG.3also shows that the cross-adjoining junction (8) between elements E1and E4with E2is a cross overlap while the cross-adjoining junction (8) between elements E4and E6with E5is an adjacent junction with no distance apart or overlap thereof.

FIG.4illustrates a detailed schematic view of a second preferred embodiment of a single heating unit (5) according to the first configuration previously described.

FIG.4clearly shows six heating elements (7) arranged both in parallel and in series in a matrix configuration by string overlaps (9) between adjacent heating elements (7) connected in series and by cross-adjoining junctions (8) between adjacent heating elements (7) connected in parallel.

In this second embodiment shown inFIG.4, the width of the heating elements E4and E6linearly decreases along the length of the heating elements (7) thereof, thus increasing the resistance as the width shortens.

Furthermore, heating elements E1and E3are made of the same material, likewise to E4and E6but different materials or geometry between each other thereof. Heating elements E2and E5comprise each else another different material or geometry to the previously mentioned.

Additionally, inFIG.4, it is shown that the cross-adjoining junction of E4and E6with E5is of 0 mm. Nevertheless, note that even a separation of a distance apart of some millimeters could be feasible for cross-adjoining junctions (not illustrated).

FIG.5illustrates another preferred embodiment of a heating unit (5). It can be seen fromFIG.5, that the matrix configuration does not need to have an equal number of rows and columns.

FIG.5shows heating element E1and E3directly connected to the terminals (6) and wherein the width of the heating elements E1and E3is reduced linearly along its corresponding length. Furthermore, the heating elements E1and E3have the same material and resistivity and in turn are overlapped to elements E2, E4and E5which in turn each comprise else different material and length.

FIG.5also shows an additional conductive element (10) which overlap both heating elements E4and E5. This may be accomplished by a metallic mesh or any other conductive sheet, fabric or mesh between two strings overlapped (8) heating elements (7). The use of a metallic mesh between two overlapped heating elements (7) can only be applied for those in transversal direction respect the electrical current flow, this is for string overlapped (9) t heating elements (7).

Note that in any of the embodiments described, the heat flux can be optimized along every single heat unit (5) and hence able to achieve an extremely accurate gradual heat flux along each individual portion of the blade to adapt to the heating flux ideally demanded. In other words, by modifying the amount of heating elements (5) in series and in parallel, thus the matrix configuration, and further modifying the material, the width and/or the thickness of every heating element (5), a very accurate profile of the heat flux to be generated along the blade can be achieved adapting very accurately to the ideal heat flux demand. Thus, the energy consumption for de-icing and anti-icing can be greatly reduced and consequently energy yield and production to the grid greatly increased. This is achieved without increasing the number of terminal cables (6) for each heating unit (5).

Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.