Solar Thermal

[j]

Anyone doing solar thermal here? Perhaps Morris?

I've just reworked my Kreamer style pass through collector. 25' * 8'
of south facing collector (+ another 16" on top). Black felt for the
pass through, SunTuf glazing with a layer of mylar underneath for double
insulation. I'm drawing the air out and ducting it into a collector box
and then distributing that into the heating vents. I'm getting about
~16,000 BTUs/hr (20F delta at ~650 CFM) when the sun shines, but I
suspect some unfound leaks.

I've got the collector divided in half so I can throttle down half
when it falls in shade. The collector sits slightly to the west of due
south and solar gain starts about 3 hours after sun up.

If anyone is working on something similar, I'll post up some pics and
data. There is a lot unknown to me at this point.

One of the other projects has been the solar cabana, which has the roof
(formed of 3/4" 10' irrigation PVC, ie thin wall) glazed in corrugated
polycarbonate with vinyl under. The sides are all single wall vinyl (~8
* 10' footprint). That heats up nicely, well into the 80's on a blustery
40F day, but of course loses heat rapidly at sun down. But during the
day a delight to pour a glass of scotch and image myself in the tropics.

Jeff

 

[Jim Wilkins]

...> You might be very pleasantly surprised by the performance of twinwall
polycarbonate glazing. If you orient the channels vertically, it may even
extend the collection day.
Morris Dovey

Do you know how it compares as collector glazing to Suntuf polycarbonate
panels from Lowe's or Home Depot?

I have roofs of Palram Suntuf over cheaper clear PVC that have held up well
to sun, weather and falling branches for several years. Although the
corrugation shapes don't match the pitch is the same and together they will
support at least two feet of snow.

I'm long-term testing what I think is the most economical durable glazing,
after being quoted ~$80 per 4'x8' sheet for the twinwall. PVC alone becomes
quite brittle from UV but one layer of Suntuf seems to protect it.

My house windows have two layers of clear Mylar film on wood frames for
extra insulation, installed in 1981 and still doing fine.

jsw

 

[j]

I'm taking a break from solar thermal to see if I can incorporate a LENR
heat source into one of my solar designs. See bottom of

http://www.iedu.com/Solar/Electricity/ and
http://www.iedu.com/Solar/Electricity/Fusion.html

Glad to see you working on something new and bold! Anything new on the
fluidyne?

Good. Seal your leaks and work to minimize the delta-T. A large delta-T
means high (re)radiation losses and airflow resistance.

It's forced air. I have a collection box 25' back from the collector
sucking air back (12" flex duct). A smaller delta-T would need a bigger
fan. When the sun drops the delta-T moves down to 5F or less.

I suspect a leak because when I close the inlet to the collector I
still have an outlet flow. I may go around with a can of spray foam
insulation. Or wait for a still day and test it with some incense sticks.

Welcome to the club. Pix and data would be welcome!

I'll post up something tomorrow. I have too much on the plate today!

You might be very pleasantly surprised by the performance of twinwall
polycarbonate glazing. If you orient the channels vertically, it may
even extend the collection day.

I haven't found a local source for twinwall. Does it have the UV shield?
I ran the Lowes version of SunTuf which is minus a UV shield and the
felt turned gray after a year or so. My understanding is that mylar can
deteriorate under UV. I moved the Lowes corrugated polycarbonate over to
the solar cabana and put in some 4 mil and 8 mil vinyl under. I suppose
I'll see what the sun does to that eventually... So, I've got 1 mil
mylar, 2 mil mylar, 4 mil vinyl and 8 mil vinyl in the test bed. If
nothing else, I'll see what fails! I think the vinyl is UV transparent,
but I don't really know.

Cheers,
Jeff

 

[j]

Do you know how it compares as collector glazing to Suntuf polycarbonate
panels from Lowe's or Home Depot?

The Lowes corrugated definitely does *not* have a UV shield.

I have roofs of Palram Suntuf over cheaper clear PVC that have held up well
to sun, weather and falling branches for several years. Although the
corrugation shapes don't match the pitch is the same and together they will
support at least two feet of snow.

I'm long-term testing what I think is the most economical durable glazing,
after being quoted ~$80 per 4'x8' sheet for the twinwall. PVC alone becomes
quite brittle from UV but one layer of Suntuf seems to protect it.

SunTuf claims something in excess of 99% UV blocking.

My house windows have two layers of clear Mylar film on wood frames for
extra insulation, installed in 1981 and still doing fine.

Wow, that's pretty good. I have some mylar interior storms that have
been up 3 years and they seem fine.

http://en.wikipedia.org/wiki/Ultraviolet

Ordinary glass is partially transparent to UVA but is opaque to shorter
wavelengths, whereas silica or quartz glass, depending on quality, can
be transparent even to vacuum UV wavelengths. Ordinary window glass
passes about 90% of the light above 350 nm, but blocks over 90% of the
light below 300 nm.[7][8][9]

Thanks for the mylar storm info.

Cheers,
Jeff

 

[Jim Wilkins]

The Lowes corrugated definitely does *not* have a UV shield.

It's on only the label side of Suntuf, both on Suntuf UV2:
http://www.palramamericas.com/docs/upload/F409_Suntuf_Install-1-21-11.pdf
See Panel Orientation on page 5.

jsw

 

[j]

It's on only the label side of Suntuf, both on Suntuf UV2:
http://www.palramamericas.com/docs/upload/F409_Suntuf_Install-1-21-11.pdf
See Panel Orientation on page 5.

I hadn't heard of the SunTuf UV2 before.

My rough understanding is that polycarbonate deteriorates under UV,
acrylic (plexiglass) does not.

http://en.wikipedia.org/wiki/Polycarbonate

UV resistance: fair

What an amazing thing Wikipedia is... that is hard to find info. I had
only heard it previously, anecdotaly.

It seems the original idea behind the UV coating was to protect the
material itself, not what is behind it. How the Lowes' polycarbonate
does this, I do not know, but it does.

Thanks for the link. I didn't know they suggest cutting with the
blade reversed...

Jeff