Comments on: And on the hardware side, the Giant Solar Funnel is live http://vinay.howtolivewiki.com/blog/hexayurt/and-on-the-hardware-side-the-giant-solar-funnel-is-live-1552 Free science and engineering in the global public interest Tue, 16 Feb 2010 17:22:50 -0800 http://wordpress.org/?v=2.8.4 hourly 1 By: Vinay Gupta http://vinay.howtolivewiki.com/blog/hexayurt/and-on-the-hardware-side-the-giant-solar-funnel-is-live-1552/comment-page-1#comment-6592 Vinay Gupta Mon, 29 Jun 2009 10:20:58 +0000 http://vinay.howtolivewiki.com/blog/?p=1552#comment-6592 William, it's a different design which looks like it might be easier to manufacture and give higher cooking performance, but we won't know until it's had some serious testing and field trials. RJ, the solar funnel wants to be as reflective as possible to concentrate the power at the bottom of the funnel, rather than absorbing heat further up. If we wanted a matt surface we could just use plastic ;-) On the cone angle, I think the optimal angle is about 45 degrees which is a bit narrower than the inventors suggest. Again, a topic of active research. Where did you get the 50 to 60 degrees figures? William, it’s a different design which looks like it might be easier to manufacture and give higher cooking performance, but we won’t know until it’s had some serious testing and field trials.

RJ, the solar funnel wants to be as reflective as possible to concentrate the power at the bottom of the funnel, rather than absorbing heat further up. If we wanted a matt surface we could just use plastic ;-)

On the cone angle, I think the optimal angle is about 45 degrees which is a bit narrower than the inventors suggest. Again, a topic of active research. Where did you get the 50 to 60 degrees figures?

]]> By: RJ http://vinay.howtolivewiki.com/blog/hexayurt/and-on-the-hardware-side-the-giant-solar-funnel-is-live-1552/comment-page-1#comment-6590 RJ Mon, 29 Jun 2009 08:41:26 +0000 http://vinay.howtolivewiki.com/blog/?p=1552#comment-6590 Vinay you made two critical errors in its construction hence the lacklustre results. You forgot to cut a semi circle out of the edge of one of the long sides. Then you fold on the semi circle giving a tighter angle of incidence. The best angle is a between 50 to 60 degrees. The result of what you have done is that the bulk of the reflected rays are bouncing out of the funnel because the funnel's angle is too wide.The funnel concentrates like a periscope not a parabola! Secondly, you used the wrong side of the aluminium foil,the matt finish side gives a far better result because it reflects less and absorbs more IR! Vinay you made two critical errors in its construction hence the lacklustre results. You forgot to cut a semi circle out of the edge of one of the long sides. Then you fold on the semi circle giving a tighter angle of incidence. The best angle is a between 50 to 60 degrees. The result of what you have done is that the bulk of the reflected rays are bouncing out of the funnel because the funnel’s angle is too wide.The funnel concentrates like a periscope not a parabola! Secondly, you used the wrong side of the aluminium foil,the matt finish side gives a far better result because it reflects less and absorbs more IR!

]]> By: William Wiltschko http://vinay.howtolivewiki.com/blog/hexayurt/and-on-the-hardware-side-the-giant-solar-funnel-is-live-1552/comment-page-1#comment-6549 William Wiltschko Mon, 15 Jun 2009 16:57:57 +0000 http://vinay.howtolivewiki.com/blog/?p=1552#comment-6549 Solar Cookers International (www.solarcookers.org) has been doing this for decades. How is this different or better? Is your distribution better? Just asking... Bill Solar Cookers International (www.solarcookers.org) has been doing this for decades. How is this different or better? Is your distribution better? Just asking…

Bill

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