BTU's of flat plate solar water collectors [RE-wrenches]

Dean T. Newberry deant at dcn.org
Fri Dec 31 10:08:53 PST 2004


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Hi Todd,

The whole story on solar incident radiation is at
http://solardat.uoregon.edu/SolarRadiationBasics.html#Ref3

The short answer is the incident radiation in the atmosphere on a sunny 
day on plane perpendicular to the sun beam is 1000 watts per square meter.
1 square meter = 10.76391 square feet.
That calcs to 92.9 Watts per square foot.
1kWh = 3413 Btu. So 92.9 W/M^2 / 1000 x 3413 Btu =  317.0781 Btu per 
square foot per hour.
The SRCC rates collectors bases on efficiency.

The Apricus is about 66% efficient at delta T 22C and 700 watts per 
square meter.
So at those conditions the Btu delivered to the heat transfer fluid is,
.7 (insolation) x .66 (collector efficiency) x 317 (Btu / sf / hr) = 
146.5 Btu / SqFt / Hour.

The SunEarth Imperial with black chrome is about 57% efficient at delta 
T 22C and 700 watts per square meter. So at those conditions the Btu 
delivered to the heat transfer fluid is,
.7 (insolation) x .57 (collector efficiency) x 317 (Btu / sf / hr) = 
126.5 Btu / SqFt / Hour.

Your collector is probably black paint. Using the SunEarth Imperial 
example with black paint at 54% efficient at delta T 22C and 700 watts 
per square meter. So at those conditions the Btu delivered to the heat 
transfer fluid is,
.7 (insolation) x .54 (collector efficiency) x 317 (Btu / sf / hr) = 
119.8 Btu / SqFt / Hour.

Your collector is 40 square feet, so the total delivered btu/hour is 40 
x 119.8 = 4794 Btu/Hour normal or perpendicular to the sun.

Plug that 4794 into the System BTU input cell on the spreadsheet at 
http://www.dcn.davis.ca.us/go/deant/ThermalCalc.xlt and you will get the 
net heat delivered in specific hour on a day in each month for your 
collectors. The spreadsheet opens with Redding sunniness and lattitude 
data, 5 in 12 slope facing south with the Angle of Incidence Modifier 
for Apricus turned on. Press the [Set Flat] button to get the 
performance of your flat collector.

Does that help??

cul  deant
*
*Tom DeBates wrote:

>Todd,
>  Two groups rating collectors are
>SRCC(www.solar-rating.org) and FSEC
>(www.fsec.ucf.edu). 
>
>Good Luck,
>
>Tom DeBates
>Habi-Tek
>Geneva,IL.
>  
>

-- 
Dean T. Newberry
Marketing and Sales

Quantum Energy Group
265 Applegate School Road, P.O. Box 158
Applegate, Ca. 95703

Email:  deant at dcn.org

Cell:   530 867-2392
Office:  530-878-4585
Fax:     530-878-6685 

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