Thanks for the info - do you have a source for the lower efficiency numbers?
I’ve seen quite a range, myself. The 80% number I’ve never seen reached unless hydrogen was the working fluid - but hydrogen is rarely the working fluid because of “little” problems like leaking and perceived fire hazards. Helium is a bit more friendly, but less efficient....
Yes, 80% is a “theoretical peak efficiency”. The practical applications of this engine to achieve generally higher efficiency range require higher mass and expense and thus relegated to mostly niche uses where they may be economical over long period of time, such as converting collected trapped heat excess into energy or where quiet is more important than efficiency.
I’ve seen references to actual efficiency from about 20% to 36%. I myself came up with lower end of that range after talking to several Segway owners and doing quick calculations, and was disappointed in efficiency because to me that was a real selling point of Segway and Kamen’s demonstrations, not the gyros (which, for stability, could be easily replaced with a three/four- wheel design, such as has been done by ZAP). Needless to say that due to small numbers involved with Segway mileage and driving range, the small variances can give wide differences in range of efficiency.
Here are some references, there was also a program on The History Channel that discussed advantages and disadvantages:
http://en.wikipedia.org/wiki/Stirling_engine
http://freeenergynews.com/Directory/StirlingEngine/index.html
http://www.stirlingengine.com/faq/one?scope=public&faq_id=1
Just ran across this; I don’t think it would be a popular thread by itself, but an interesting update on Segway:
http://www.sfgate.com/cgi-bin/article.cgi?f=/n/a/2007/08/08/financial/f161626D82.DTL&type=printable
Segway scooter user group folds due to lack of interest
Wednesday, August 8, 2007
San Francisco (AP) —
The device that was supposed to revolutionize urban transportation seems unable to even hold on to a proper fan club.
The Segway Enthusiasts Group of America is disbanding because of inactivity and an absence of candidates for its board of directors, said the group’s treasurer, Fred Kaplan.
SEG America plans to cease operations at the end of this month. Other small fan groups for the Segway still exist, but SEG America was one of the more active organizations, sending out regular e-mails on various Segway-related gatherings.
.....
When the Segway debuted, executives at the exclusive preview predicted that it would have no trouble selling and that entire U.S. cities would eventually be designed to take advantage of its capabilities — which can move people at up to 12 mph.
Still, the Segway can be too pricey for even for personal electronics-hungry American consumers. The base model Segway PT i2 carries a suggested retail price of $5,145, and SEG America’s Kaplan says replacement batteries cost about $1,600 per pair.