Article 31547 of alt.solar.thermal: Path: news.misty.com!not-for-mail From: nicksanspam@ece.villanova.edu Newsgroups: alt.solar.thermal Subject: Re: cheap and easy space heater panel? Date: 23 Dec 2008 06:39:10 -0500 Organization: Villanova University Lines: 23 Message-ID: References: <5364b731-021a-480f-92a8-eea359c434a8@k18g2000yqj.googlegroups.com> NNTP-Posting-Host: acadia.ece.villanova.edu X-Trace: max.inside.misty.com 1230032352 22729 153.104.44.130 (23 Dec 2008 11:39:12 GMT) X-Complaints-To: abuse@misty.com NNTP-Posting-Date: Tue, 23 Dec 2008 11:39:12 +0000 (UTC) Xref: news.misty.com alt.solar.thermal:31547 schooner wrote: >>>> An empty box would have fewer parts :-) >>> >>>No baffles or absorber panels? >> >> Right, altho a transpired mesh absorber (eg dark window screen) >> would improve efficiency. > >As would any absorber plate, such as a flat plate or say aluminum ducting. >But then that is more parts isn't it? ;-) The back of the box can be the "absorber plate." Slower-moving air near the inside surface of the glazing improves solar collection efficiency, but an absorber plate with air moving behind it may not add much, compared to a box that is deep enough to make a low air velocity near the glazing. A transpired mesh can be more efficient, since it can keep cool room air vs sun-warmed air between the mesh and the glazing and block some reradiation from the back of the box to the glazing. Nick