Article 30355 of alt.solar.thermal: Path: news.misty.com!not-for-mail From: nicksanspam@ece.villanova.edu Newsgroups: alt.solar.thermal Subject: Re: Overnight air heater thermal storage Date: 27 Apr 2008 08:45:16 -0400 Organization: Villanova University Lines: 80 Message-ID: References: NNTP-Posting-Host: acadia.ece.villanova.edu X-Trace: max.inside.misty.com 1209296704 24569 153.104.44.130 (27 Apr 2008 11:45:04 GMT) X-Complaints-To: abuse@misty.com NNTP-Posting-Date: Sun, 27 Apr 2008 11:45:04 +0000 (UTC) Keywords: sanspam Xref: news.misty.com alt.solar.thermal:30355 > 8' > ------------------------------------------ > | | | > | | ----------- | > | | | | | > | | | --- | | > | | | | | ^ | ^ | > | | | | | | | | | > | | | | | | | > | | | | | |c | > | | | | |h |o | > | | | | |o |o | > | | | |h |t |l | > | | | |o | | | > | |Cc |Ch |u |Tha|Tca| 8' south --> > | | | |s | | | > | | | |e |c |c | > | | | | |a |a | > | | | |w |v |v | > | | | |a |i |i | > | | | |l |t |t | > | | | |l |y |y | > | | | | | | | > | | | | | | | > | | | --- | | > | | | | | > | | ----------- | > | | | > ------------------------------------------ > >We might replace the corrugated polycarbonate glazing and window screen in >Gary's nice 12/06 MEN air heater described at http://builditsolar.com and >http://www.motherearthnews.com/multimedia/image-gallery.aspx?id=74688&seq=1 >with a $64 4'x16'6.5" UPS-shippable 3-pound roll of 0.007" GE HP92W Lexan >folded over a flat 2x4 at the top, with a bottom tensioning spring to make >a 3.5"-deep outer cool cavity and a 2" inner hot cavity and solar thermal >cogeneration, as above, viewed in a fixed font... >With more thermosyphoning airflow and exponential vs linear warming and finite >airfilm conductance and passive thermal control details, we might end up with >a 2x3 cool wall and a 2x4 hot wall... Looks OK so far: 20 AC=6*8*8'cube surface (ft^2) 30 RV=15'US R-value of cube walls 40 GC=AC/RV'cube conductance (Btu/h-F) 50 TA=30'outdoor temp (F) 60 SUN=1000'average sun on south wall (Btu/ft^2-day) 70 CH=8'solar collection hours 80 TR=70'room temp (F) 90 QH=(TR-TA)*GC'hourly heatflow (Btu/h) 100 QN=16*QH'overnight heat 110 QD=24*QH'daily heatflow (Btu/day) 120 AS=8*8'south glazing area (ft^2) 130 RS=1'south glazing resistance (per layer) 140 TS=.92'south glazing transmittance (per layer) 150 SSS=TS^2*AS*SUN'sun entering south glazing (Btu/day) 160 TCA=TA+RS*(SSS-QD)/CH/AS'average cool cavity temp (F) 170 AV=8*8/12'vent area (ft^2) 180 H=8'vent height difference (ft) 190 DT=(QH/11.7/AV/SQR(H))^(2/3) 200 AN=8*8'1-sided overnight heat store area (ft^2) 210 UA=1.5'slow airfilm conductance (Btu/h-F-ft^2) 220 TMIN=TR+DT+QH/(2*UA*AN)'dawn heat store temp (F) 230 TMAX=2*TCA-TMIN'max cool cavity temp (F) 240 CN=QN/(TMAX-TMIN)'overnight heat capacity 250 DN=12*CN/AN/62.33'overnight store depth (inches) 260 PRINT TMIN,TMAX,DN 270 THA=TMAX+SSS*RS/AS/CH'hot store temp (F) 280 CC=5*QD/(THA-TMIN)'hot store cap (Btu/F) 290 DC=12*CC/AN/62.33'hot store depth (inches) 300 PRINT TMIN,THA,DC 78.56218 97.03782 2.667623 78.56218 202.8378 2.974399 Nick