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Ottermo, Fredric
Publications (10 of 16) Show all publications
Möllerström, E., Gipe, P., Beurskens, J. & Ottermo, F. (2019). A historical review of vertical axis wind turbines rated 100 kW and above. Renewable & sustainable energy reviews, 105, 1-13
Open this publication in new window or tab >>A historical review of vertical axis wind turbines rated 100 kW and above
2019 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 105, p. 1-13Article, review/survey (Refereed) Published
Abstract [en]

This paper summarizes and introduces all vertical axis wind turbine (VAWT) projects where 100 kW or larger turbines have been installed. The basis for the review is both existing literature and personal correspondence with people once involved in the different developments. By citing the most relevant work for each project, the paper will also work as an information hub, making information on these projects more accessible.

Since the 1970s, there have been several VAWT projects with installed turbines of significant size, either as attempts to commercialize VAWTs, or as university led research projects, or as a combination of the two. Most have involved Darrieus turbines built in North America during the 1980s. However, H-rotors, which have always been a favored concept in Europe, have seen a revival during the 2010s.

The reason VAWTs have never fully challenged the success of the horizontal axis wind turbine (HAWT) is too broad a question to answer here. However, the reasons some VAWT projects have failed are addressed in this paper. Besides the fact that many of the prototypes had terminal failures, most of the installed medium or large-scale VAWTs have to some extent had problems with metal fatigue and durability. Additionally, a lack of long-term interest from governmental or private funders, as well as the introduction of reliable HAWTs, was a recurring theme from those involved in VAWT development, regarding the reason VAWTs so far have failed to succeed. © 2018 The Author(s)

Place, publisher, year, edition, pages
Kidlington: Pergamon Press, 2019
Keywords
Vertical axis wind turbine, VAWT, Darrieus-turbine, H-rotor, Wind turbine history
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-38798 (URN)10.1016/j.rser.2018.12.022 (DOI)000460121000001 ()2-s2.0-85060475951 (Scopus ID)
Available from: 2019-01-27 Created: 2019-01-27 Last updated: 2019-03-21Bibliographically approved
Möllerström, E. & Ottermo, F. (2019). Calculational model for first-mode eigenfrequency of a semi-guy-wired vertical-axis wind turbine tower. Wind Engineering: The International Journal of Wind Power
Open this publication in new window or tab >>Calculational model for first-mode eigenfrequency of a semi-guy-wired vertical-axis wind turbine tower
2019 (English)In: Wind Engineering: The International Journal of Wind Power, ISSN 0309-524X, E-ISSN 2048-402XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

A simple model for accounting for tower mass when estimating the first-mode eigenfrequency of a semi-guy-wired tower has been derived. This extends previous work where an analytical model of the semi-guy-wired tower of a 200-kW vertical-axis wind turbine was developed. The model was primarily used to estimate the eigenfrequencies as a result of adding guy wires to a free-standing tower (thus creating a semi-guy-wired setup). However, a weakness with the model was that the tower mass was accounted for in a rough way that essentially ignored the guy wires, which gave a larger-than-necessary error. In this work, an effective top mass, that takes into account the tower mass and the constraints from the guy wires, is derived to achieve a higher accuracy when estimating the first-mode eigenfrequency. This, together with the earlier models, gives a more complete method to estimate the eigenfrequencies for a semi-guy-wired wind turbine.

Place, publisher, year, edition, pages
London: Sage Publications, 2019
Keywords
Vertical-axis wind turbine, eigenfrequency, natural frequency, semi-guy-wired
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-40775 (URN)10.1177/0309524X19882433 (DOI)
Available from: 2019-10-22 Created: 2019-10-22 Last updated: 2019-10-23
Möllerström, E. & Ottermo, F. (2019). Comparison of inflow-turbulence and trailing-edge noise models with measurements of a 200-kW vertical axis wind turbine. Paper presented at WindEurope Conference and Exhibition 2019, Bilbao, Spain, 2–4 April, 2019. Journal of Physics, Conference Series, 1222, Article ID 012028.
Open this publication in new window or tab >>Comparison of inflow-turbulence and trailing-edge noise models with measurements of a 200-kW vertical axis wind turbine
2019 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 1222, article id 012028Article in journal (Refereed) Published
Abstract [en]

Models of inflow-turbulence noise and turbulent-boundary-layer trailing-edge noise are compared to earlier measurements of a 200-kW vertical axis wind turbine so that conclusions regarding the origin of the aerodynamic noise can be drawn. The measurement campaigns, which aimed at establishing the noise emission value and locating the aerodynamic noise sources with a microphone array, are here both compared to further modified versions of the trailing-edge and inflow-turbulence models respectively. Unlike the case for horizontal axis wind turbine, inflow-turbulence noise is deemed as the prevailing noise mechanism. Reducing the self-induced turbulence could then be an effective way of lowering the noise levels for vertical axis wind turbines. Also, looking at the directivity of the inflow-turbulence noise model which indicate most noise in the cross-wind directions, a deviation from the standard downwind measurement position for measuring noise emission is suggested for the VAWT case.

Place, publisher, year, edition, pages
Bristol: Institute of Physics (IOP), 2019
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-39459 (URN)10.1088/1742-6596/1222/1/012028 (DOI)
Conference
WindEurope Conference and Exhibition 2019, Bilbao, Spain, 2–4 April, 2019
Available from: 2019-05-23 Created: 2019-05-23 Last updated: 2019-06-07Bibliographically approved
Averfalk, H., Ottermo, F. & Werner, S. (2019). Pipe Sizing for Novel Heat Distribution Technology. Energies, 12(7), Article ID 1276.
Open this publication in new window or tab >>Pipe Sizing for Novel Heat Distribution Technology
2019 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 7, article id 1276Article in journal (Refereed) Published
Abstract [en]

This paper assesses pipe sizing aspects for previously proposed, novel, low heat distribution technology with three pipes. Assessment issues include heat loss, pressure loss, and pipe sizing for different typical pipe configurations. This assessment has been provided by the analysis of a case area with single-family houses. Concerning heat loss, the proposed three-pipe solutions have the same magnitude of heat loss as conventional twin pipes, since lower return temperatures compensate for the larger heat loss area from the third pipe. Regarding pressure loss, the main restriction on the size of the third pipe is limited to the pressure loss in the third pipe. Thermostatic valves to manage the flow rate of the third pipe are advocated, since alternative small pumps have not been found to be commercially available. The pipe sizing recommendation is that the third pipe for recirculation purposes can be two to three standard pipe sizes smaller than the corresponding supply and return pipe, if no prosumer is connected in the heat distribution network.

Place, publisher, year, edition, pages
Basel: MDPI, 2019
Keywords
low temperature, district heating, pressure gradients, three-pipe system, 4GDH-3P
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-39198 (URN)10.3390/en12071276 (DOI)
Projects
TEMPO
Funder
EU, Horizon 2020, 768936
Available from: 2019-04-04 Created: 2019-04-04 Last updated: 2019-04-04Bibliographically approved
Ghadirinejad, N., Ottermo, F. & Hoseinzade, A. (2018). Experimental Evaluation, Simulation and Statistical Analysis of a Humidification-Dehumidification Solar Desalination System. In: : . Paper presented at 23rd International Congress of Chemical and Process Engineering (CHISA 2018), Prague, Czech Republic, 25-29 Aug., 2018.
Open this publication in new window or tab >>Experimental Evaluation, Simulation and Statistical Analysis of a Humidification-Dehumidification Solar Desalination System
2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Inspired by the precipitation cycle, the Humidification-Dehumidification (HDH) method is based on evaporation and consecutive condensation in a natural loop. The heat input to the system is provided by a solar collector, making the system suitable for remote locations with access to sea water and good insolation. In this study investigated parameters included temperatures and flow rates of cooling water, cycled air, and water intake to humidifier, as well as the height of packed bed column. A series of simulations has been performed in the ASPEN Plus software, in order to obtain optimum physical parameters in this desalination system. The experimental results showed that at constant heat flux and optimum air flow rate, three parameters have strong influence on the production of distilled water: the flow rate of cooling water, the flow rate of water inlet and its temperature augmentation. Moreover, although increasing flow rate of cooling water leads to an increase in the distilled water flow rate, this effect is mitigated at high rates. The most reliable Height Equivalent to a Theoretical Plate (HETP) model of random packing has been found by opting for the model of Mangers & Ponter. The estimated error of the model in predicting the height of the packed bed was less than 4%. Regarding closed versus open air flow; the closed air system provided an efficiency of distilled water production up to 15% higher than the open air system for the same conditions. This increase is a result of prevention of the loss of air humidity at the condenser outlet. A regression analysis was performed, which indicates that the HDH system can be well described by a linear model for the logarithm of the rate of desalinated water. The variables used are the saline water flow rate, the heat transfer rate in the solar collector and the air flow rate. The adjusted R-squared of the fit was computed as 89.8%.

Keywords
Energy engineering, Solar desalination
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-38158 (URN)
Conference
23rd International Congress of Chemical and Process Engineering (CHISA 2018), Prague, Czech Republic, 25-29 Aug., 2018
Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2019-01-04Bibliographically approved
Ottermo, F., Möllerström, E., Nordborg, A., Hylander, J. & Bernhoff, H. (2017). Location of aerodynamic noise sources from a 200 kW vertical-axis wind turbine. Journal of Sound and Vibration, 400, 154-166
Open this publication in new window or tab >>Location of aerodynamic noise sources from a 200 kW vertical-axis wind turbine
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2017 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 400, p. 154-166Article in journal (Refereed) Published
Abstract [en]

Noise levels emitted from a 200 kW H-rotor vertical-axis wind turbine have been measured using a microphone array at four different positions, each at a hub-height distance from the tower. The microphone array, comprising 48 microphones in a spiral pattern, allows for directional mapping of the noise sources in the range of 500 Hz to 4 kHz. The produced images indicate that most of the noise is generated in a narrow azimuth-angle range, compatible with the location where increased turbulence is known to be present in the flow, as a result of the previous passage of a blade and its support arms. It is also shown that a semi-empirical model for inflow-turbulence noise seems to produce noise levels of the correct order of magnitude, based on the amount of turbulence that could be expected from power extraction considerations.

Place, publisher, year, edition, pages
London: Elsevier, 2017
Keywords
Vertical-axis wind turbine, H-rotor, Noise, Microphone array, Beamforming
National Category
Energy Engineering Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:hh:diva-33813 (URN)10.1016/j.jsv.2017.03.033 (DOI)000402355100011 ()2-s2.0-85019218669 (Scopus ID)
Funder
StandUpStiftelsen Olle Engkvist Byggmästare
Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2018-03-23Bibliographically approved
Möllerström, E., Ottermo, F., Hylander, J. & Bernhoff, H. (2016). Noise Emission of a 200 kW Vertical Axis Wind Turbine. Energies, 9(1), Article ID 19.
Open this publication in new window or tab >>Noise Emission of a 200 kW Vertical Axis Wind Turbine
2016 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 9, no 1, article id 19Article in journal (Refereed) Published
Abstract [en]

The noise emission from a vertical axis wind turbine (VAWT) has been investigated. A noisemeasurement campaign on a 200 kW straight-bladed VAWT has been conducted, and the result hasbeen compared to a semi-empirical model for turbulent-boundary-layer trailing edge (TBL-TE) noise.The noise emission from the wind turbine was measured, at wind speed 8 m/s, 10 m above ground, to96.2 dBA. At this wind speed, the turbine was stalling as it was run at a tip speed lower than optimaldue to constructional constraints. The noise emission at a wind speed of 6 m/s, 10 m above groundwas measured while operating at optimum tip speed and was found to be 94.1 dBA. A comparisonwith similar size horizontal axis wind turbines (HAWTs) indicates a noise emission at the absolutebottom of the range. Furthermore, it is clear from the analysis that the turbulent-boundary-layertrailing-edge noise, as modeled here, is much lower than the measured levels, which suggests thatother mechanisms are likely to be important, such as inflow turbulence.

Place, publisher, year, edition, pages
Basel: MDPI, 2016
Keywords
vertical axis wind turbine (VAWT), H-rotor, noise, noise emission, sound power level
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-27523 (URN)10.3390/en9010019 (DOI)000369501500013 ()2-s2.0-84956619748 (Scopus ID)
Funder
StandUp
Available from: 2015-01-19 Created: 2015-01-19 Last updated: 2018-03-22Bibliographically approved
Möllerström, E., Eriksson, S., Goude, A., Ottermo, F. & Hylander, J. (2016). Turbulence influence on optimum tip speed ratio for a 200 kW vertical axis wind turbine. Paper presented at 6th Science of Making Torque from Wind Conference, Technical University of Munich, Munich, Germany, Oct. 5-7, 2016. Journal of Physics, Conference Series, 753, Article ID 032048.
Open this publication in new window or tab >>Turbulence influence on optimum tip speed ratio for a 200 kW vertical axis wind turbine
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2016 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 753, article id 032048Article in journal (Refereed) Published
Abstract [en]

The influence of turbulence intensity (TI) on the tip speed ratio for maximum power coefficient, here called λCp-max, is studied for a 200 kW VAWT H-rotor using logged data from a 14 month period with the H-rotor operating in wind speeds up to 9 m/s. The TI - λCp-max relation is examined by dividing 10 min mean values in different turbulence intensity ranges and producing multiple CP(λ) curves. A clear positive relation between TI and λCp-max is shown and is further strengthened as possible secondary effects are examined and deemed non-essential. The established relation makes it possible to tune the control strategy to enhance the total efficiency of the turbine.

Place, publisher, year, edition, pages
Bristol: Institute of Physics Publishing (IOPP), 2016
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-32175 (URN)10.1088/1742-6596/753/3/032048 (DOI)000436325701024 ()2-s2.0-84995467631 (Scopus ID)
Conference
6th Science of Making Torque from Wind Conference, Technical University of Munich, Munich, Germany, Oct. 5-7, 2016
Funder
StandUp
Available from: 2016-10-09 Created: 2016-10-09 Last updated: 2019-02-01Bibliographically approved
Möllerström, E., Ottermo, F., Goude, A., Eriksson, S., Hylander, J. & Bernhoff, H. (2016). Turbulence influence on wind energy extraction for a medium size vertical axis wind turbine. Wind Energy, 19(11), 1963-1973
Open this publication in new window or tab >>Turbulence influence on wind energy extraction for a medium size vertical axis wind turbine
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2016 (English)In: Wind Energy, ISSN 1095-4244, E-ISSN 1099-1824, Vol. 19, no 11, p. 1963-1973Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Chichester: John Wiley & Sons, 2016
Keywords
VAWT, H-rotor, turbulence intensity, power coefficient curve
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-30366 (URN)10.1002/we.1962 (DOI)000386149700001 ()2-s2.0-84990178448 (Scopus ID)
Funder
StandUp
Available from: 2016-02-19 Created: 2016-02-19 Last updated: 2018-03-22Bibliographically approved
Möllerström, E., Bolin, K., Ottermo, F., Bååth, L. & Hylander, J. (2015). Noise directivity from a vertical axis wind turbine. In: Proceedings of the 6th International Conference on Wind Turbine Noise 2015: . Paper presented at The 6th International Conference on Wind Turbine Noise (WTN2015), Glasgow, Scotland, 20-23 April, 2015. New Brighton: INCE/Europe
Open this publication in new window or tab >>Noise directivity from a vertical axis wind turbine
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2015 (English)In: Proceedings of the 6th International Conference on Wind Turbine Noise 2015, New Brighton: INCE/Europe , 2015Conference paper, Published paper (Other academic)
Abstract [en]

The directivity of wind turbine noise is of widespread interest and has received attention over an extended period. The reason for this is partly that noise optimization procedures can be implemented in order to increase the efficiency of the power output. Although directivity of horizontal axis wind turbines (HAWTs) are well understood, the directivity pattern around vertical axis wind turbines (VAWTs) are less well investigated.This paper presents measurements of directivity on a 200 kW VAWT, a so called H-rotor, with variable speed and a tower height of 40 m. The turbine, which is situated in a flat agricultural landscape close to Falkenberg at the Swedish west coast, is one of the world’s largest today operational VAWTs. Experimental results as well as a theoretical model based on the turbulent-boundary-layer trailing-edge (TBL-TE) noise suggest higher noise levels upwind of the rotor and the lowest noise levels in the perpendicular directions. Moreover, modulation analysis of the measurements indicates the presence of modulations but the results are inconclusive.

Place, publisher, year, edition, pages
New Brighton: INCE/Europe, 2015
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-28164 (URN)
Conference
The 6th International Conference on Wind Turbine Noise (WTN2015), Glasgow, Scotland, 20-23 April, 2015
Funder
StandUp
Available from: 2015-04-27 Created: 2015-04-27 Last updated: 2018-03-22Bibliographically approved
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