Hoagy,
I sent the following to the wind list, --------------------------------- I am a long time member of the biofuel list and usually post all what I do on this list. A member "Hoagy" made a very important comment. He pointed me to a wind primer made by Dr. Gary L. Johnson, "Wind Energy Systems" <http://www.eece.ksu.edu/~gjohnson/>http://www.eece.ksu.edu/~gjohnson/ In chapter 1, page 1-17, Dr. Johnson make the following remark, "A chart of efficiency of five different turbine types is shown in Fig. 8. The efficiency or power coefficient varies with the ratio of blade tip speed to wind speed, with the peak value being the number quoted for a comparison of turbines. This will be discussed in more detail in Chapter 4. It may be noticed that the peak efficiencies of the two bladed propeller, the Darrieus, and the Savonius are all above 30%, while the American Multiblade and the Dutch windmills peak at about 15%. These efficiencies indicate that the American Multiblade is not competitive for generating electricity, even though it is almost ideally suited and very competitive for pumping water. The efficiency curves for the Savonius and the American Multiblade have been known for a long time [6, 10]. Unfortunately, the labels on the two curves were accidentally interchanged in some key publication in recent years, with the result that many authors have used an erroneous set of curves in their writing. This historical accident will probably take years to correct." I belong to one who almost in all literature have seen the Savonius efficiency set to 14% and this is probably wrong. It seems that most of us commits to this mistake and it is important to correct it. The curves shown are very interesting as is the whole primer. Hakan ----------------------------------------------------------------- At 20:40 08/01/2004, you wrote: > > you wrote: > > > > Hoagy, > > > > Thanks, it was very interesting and I missed it. Need to check it, but if > > it is right it is quite a big thing. All literature I looked at, set the > > Savonius at 14%, but also the American Multiblade at 14%. Will be > > interesting to explore. LOL > > > > He is right, it will take decades to correct. > > > > Hakan > > >The information is interesting Hakan and Dr. Johnson >does led up to his summary with reference material >so I thought it might have coincided with the >newer development you'd mentioned previously >along with the reference link you'd given earlier >but includes photo with caption from ><http://www.aerotecture.com/projects/view.nhtml?profile=projects&UID=10009>http://www.aerotecture.com/projects/view.nhtml?profile=projects&UID=10009 > > >with reference to the blade configuration. Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/index.php?list=biofuel Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Yahoo! Groups Links To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
