Welcome everybody to the first post of my new blog dedicated to what I hope will become a new and important technology in solar energy capture. Read about how I came up with the idea, read about the idea itself, read a little more about why I made this blog, download and print a little white paper I wrote, check out the instructable I set up, and contact me if you have any questions or think you know how you can be a part of this project. I will be using feedback I get on this site to help guide my posts.
Check out the video I made of my first plastic particle panel below.
I have received some comments that indicate some confusion as to why these panels are a good idea, or what the innovation is. That means I am not doing a good job in explaining things. Let me try:
This design reduces the cost and weight by 80% and is many times more durable (because there is no glass). The result is a solar thermal panel that is much cheaper, much lighter, many time more durable and equally (or perhaps more?) efficient as what is on the market today.
That why I think this is a good idea. Please call me on this if I am wrong or you see any problems with my logic.
note about the video: I think the stuff I say about the turbulent flow being less resistive to flow is not correct. I think its actually opposite. Anyway, something to look into. If anybody out there can explain to me how/why those convection current are set up, please leave a comment!
Is that polycarbonate?
ReplyDeleteyes, it is. As it turns out polycarbonate can be damaged by water at high temperatures (over 60C I think). For a production panel, another plastic would have to be used, a coating applied to the polycarbonate, or the control system must turn the panels off if the system gets close to the hydrolysis temps. Solvable problem I think.
ReplyDeleteHi Alex,
ReplyDeleteLooks like fun, but as you say polycarbonate will degrade in regular performance.
PC and water will eventually make the PC brittle and fail.
It is not a simple issue to reconcile, but the concept is fun to play with. Most solar pool collectors work with other plastics in the same fashion.
Hi Alex,
ReplyDeleteYour solution to the overheating problem is ingenious. I watched your video with keen anticipation waiting to see the panel darken when the water began to flow. Absolutely beautiful. A couple questions: Your whitepaper indicates 750-830 W/m^2 power output. That seems quite high and I was wondering what the range of water temperature and ambient temperature were for that test. I assume based on the high values that you were simply passing cold water through the panel and measuring the temperature rise? Have you set up a closed loop with pump yet and measured the average power output while heating water from say 25°C to 50°C (a typical home heating range)? Also, you say "the distance that the heat must travel to reach the water is only the particle radius" but in fact, the distance is 0 since the surface of the particle is the location of heat "generation", not the center of the particle. In that case the thermal conductivity of the absorber is irrelevant, and it makes for a VERY efficient panel. I look forward to the day I can buy one of your panels off the shelf. Best of luck and I'll definitely keep an eye on your blog. -Rob
Thanks Rob! yeah, you guessed my method of measuring the output. This was for an uninsulated panel. I pumped cold water for a minute, measured the temp rise on the output port, then measured the water volume. Long story short, I had huge variance (i measured 95% at one point but figured that was a mistake). I would not trust these numbers just yet, however as you mention the design does lend itself to very high efficiencies, so i expect high numbers. I really need to do a closed loop test. I want to work an another version with a better manifold, insulate it, and hook it up to a closed loop pump. Man I wish I had the time right now. leaving for a week-long business trip today. :(
ReplyDeletehello all, I am appreciative of your making, and I want to know what is the use of silicon carbonate particles.
ReplyDeleteIn France (I'm French) no body's perfect, those who have tried with these easter had sealing problems between the polycarbonate and the collector.
What adhesive did you used to Resit heat and expansion?
1) The silicon carbonate particles are used for absorbing the light. Any small black particle that does not dissolve in water would probably work. Its the only particle I could find that was available pre-sifted into a uniform size.
ReplyDelete2) I am no longer attempting to use polycarbonate because it degrades in water. I am currently looking at acrylic or polypropylene.
3) the best solution is to weld the plastic, not to use adhesive. However, assuming the surfaced to be joined are perfectly flat, acrylic and polycarbonate can be solvent welded.
Just an idea Aex: Why not pump* a heavily dyed-black anti-freeze* through the primary system and then use a heat exchanger to transfer the heat out into secondary system. Inefficiencies aside, at least you can exclude toxins like BPA from entering the secondary system (or even pool chemicals from entering the primary). You'll need to actively pump so that the panel drains when not in use -- to prevent overheating through absorption. Harry
ReplyDelete*or some other solution that doesn't degrade polycarbonate
Harry,
ReplyDeleteplease see my May 1st post which explains why I am not fond of this solution. Other tried this in the 70's. Some googling will dig that work up.
1) its very hard to get a black liquid to remain stable in suspension and not degrade after long exposure to the sun
2) It creates a disposal problem
3) Its expensive (you have to buy a lot of anifreeze)
4) It is not clear to me that antifreeze will not degrade after exposure to the sun (if you have data on this, please let me know)
5) I plan to use the panels to power space heaters that include a mass of water to store the heat and radiate it at night. Its hard to stomach the thought of a vat of black antifreeze spilling all over the room if something went wrong. (a leak from the hose, a container spilling, etc)
Alex, yes, after I rummaged around your site I did come across your follow up "ink" article. Since you won't be immersing yourself in the hot water I think your solution is probably best for space heating -- but to heat a hot tub/pool (which is what I'm interested in) I have reservations about what chemicals are leeched out of plastics into hot water. A heat exchanger offers a method of isolation. Thanks, Harry
ReplyDeleteHarry, I also don't plan on using polycarbonate for exactly the use you bring up. Acrylic is a better choice, and its bio-compatible (you inject it or inject it without problems).
ReplyDeleteUse glass instead of plastic. Source? Check the craigslist adds for people getting rid of old sliding glass doors. Very affordable, and keeps them from the land fills. You can also get old ones from window/glass installers. They are usually happy to get rid of them.
ReplyDeleteFor several years I've been wanting to install floor heating using pex tubing (ebay) and a solar collector from old sliding doors. Should be easy to accomplish, just haven't pulled the trigger to get it started.
The solar collector would use coils of pex tubing between the glass panels. It "should" work.
venturahandyman@aol.com