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- Möllerström, Erik, 1984-, et al.
(författare)
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Turbulence influence on wind energy extraction for a medium size vertical axis wind turbine
- 2016
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Ingår i: Wind Energy. - Chichester : John Wiley & Sons. - 1095-4244 .- 1099-1824. ; 19:11, s. 1963-1973
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Tidskriftsartikel (refereegranskat)abstract
- The relation between power performance and turbulence intensity for a VAWT H-rotor is studied using logged data from a 14 month (discontinuous) period with the H-rotor operating in wind speeds up to 9 m/s. The turbine, designed originally for a nominal power of 200 kW, operated during this period mostly in a restricted mode due to mechanical concerns, reaching power levels up to about 80 kW. Two different approaches are used for presenting results, one that can be compared to power curves consistent with the International Electrotechnical Commission (IEC) standard and one that allows isolating the effect of turbulence from the cubic variation of power with wind speed. Accounting for this effect, the turbine still shows slightly higher efficiency at higher turbulence, proposing that the H-rotor is well suited for wind sites with turbulent winds. The operational data are also used to create a Cp(λ) curve, showing slightly lower Cp compared with a curve simulated by a double multiple streamtube model. Copyright © 2016 John Wiley & Sons, Ltd.
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| 2. |
- Tonderski, Karin S., et al.
(författare)
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Våtmarker : Närsaltsfällor och/eller myllrande mångfald?
- 2003
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Ingår i: Vatten: tidskrift för vattenvård. - Nykvarn : Föreningen Vatten. - 0042-2886. ; 59:4, s. 259-270
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the state-of-the-art with respect to wetlands for nutrient removal and biodiversity enhancement, as expressed at a research workshop in December 2002. In the end of 2002, 260 and 884 wetlands had been constructed in Sweden with subsidies from LIP and the European Union, respectively. Most frequently, the aims were to remove nutrients from water and enhance biodiversity. The question raised is if we know how to design multifunctional wetlands. Should a wetland be deep or shallow, with or without macrophytes to be an efficient nutrient sink? Diverging opinions are presented, but generally it appears that fairly shallow wetlands at least partly covered by emergent macrophytes are favourable. The importance of extreme high flows and hydraulic short-circuiting is highlighted, and Danish and Norwegian approaches to wetlands construction are presented. Also, there is a risk that nutrient retaining wetlands develop a fairly trivial flora and fauna unless special care is taken. Intentional establishment of desirable and less common species, as well as creation of a variation of depth gradients to favour such species are such measures. Others are allowing for water level variations, as well as vegetation management such as grazing and harvesting.
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