Solar Water Heating Idea

It seems a rather convoluted way of doing it...
You need surface area this worked for me, cheap and simple.
Del

Glass or ceramic bead media would be my first choice. Density about right, size and color adjustable, low or no toxicity (inert).

Is this idea really that much more efficient or less expensive than the "simple" solutions (like Del's) that have been working fine for many decades?

Sorry, I keep trying to apply those pesky things called physics, math, and cost. Best wishes on your project.

@ Del: I don't think it is convoluted, on the contrary, it is stunningly simple. The surface area equals the total surface of all the particles exposed to the sun. @ mjb: I agree about glass or ceramic beads, or maybe graphite. The problem is: where to obtain them, off the shelf? What industry is using these kind of beads or balls? As for efficiency: I'm trying to find a low-cost lightweight low-risk heat-storage solution for the (hybrid) solar fruitdryers I'm building in Africa. The panels will consist of the double wall (acrylic or polypropylene) used for 'glazing' patios etc., actually square tubes between two sheets. @ DVader: Yes, the beads will occupy space, up to 1/6 of the tube's volume, but there is no transfer-loss because the surface of the beads is in contact with the water. Another great advantage is that the panel won't overheat when there is no water flowing, it switches itself 'off' because the particles will sink to the bottom.

I gave you a hint in my first 5 words, but here it is again...

Do a Google search for "Glass or ceramic bead media"

and proceed from there. Good luck.

@ mjb: Thanks for repeating, I didn't take it as a searching hint at first but turns out very fruitful, just what I was looking for! BLACK beads remain a problem though. @ Del: No traces of nut found in your answer. You're right concerning surface. However, I'm not going to use "glass tubes" (as explained in #4). And lightweight and low-cost are high priorities, as well as non-vulnerability. @ kebang: I think the movement of the particles, touching the inside everywhere, will keep the the panel free of algea, don't you? If not, I could still add a few grains of sodium carbonate now and then. see this video: http://www.particlepanels.com/2010/02/here-we-go.html (sorry, linking nor spacing seem to work...)

love that site/video.. brilliant engineering and inventing.

Of course you are free to dissagree...but have you thought about the problems of sealing glass tubes and linking them up...
The surface area of the particles isn't very good as if you take one spherical particle, only half is exposed to the sun, and much of that is exposed at an oblique angle, the one particle will then shade some of the others.
BUT... if you had flat particles laid out flat with no gaps between...ah! we call this a sheet!
A sheet of black material with a glass face plate...(plate is cheaper than tube) with water trickling over the surface. This would be cheaper, simpler to make and more effective. Other than that I totally agree with you.
Del

Yes, your idea will work, but why not simply use black painted copper pipes to carry the water? After all, the beads in your concept will occupy space and reduce the water carrying capacity of your tubes.

An effective, cheap and simple answer, therefore a GA from me.

Why go to the bother of searching for some black beads.....a total waste of time, probably money as well and wait up for possible pump problems if just one escapes into the system...... impractical.

K.I.S.S. is the master word.......

If the simple system is a few % less effective (I doubt that but just in case) then build the simple system a tad larger......remember, the energy is free in the first place, so taking a little bit more of it is not a failure. Thats why I would never buy the evacuated glass tubes unless I only had a tiny area to use AND money was no object!!

I worked at a small solar factory back in the early eighties... We put together some Siemens evacuated tube collectors with 8 tubes.. could boil water in 2 minutes! faster than the kettle. neat and easy to maintain. (socket type adapters)

Chris

...but not cheap......

If its a DIY project and costs are a problem, you can build something with a greater catchment area for a small part of the costs of a complete system.

My Daughters Grandparents in law paid almost $50,000 for a system recently. Its good, but payback will take over 30 years at the present energy costs.....and their roof STILL leaks.......they would have been better off getting the roof right!!!

I think you will have a serious problem with a quick buildup of algea inside the transparent tube, rapidly reducing the efficiency of the unit...

Hi Fredart,

Please let me know your e-mail add I will send you detailed write up on DIY Home made Solar Water Heater. It is cheaper way of making Solar Water Heater.

Regards,

Suresh Sharma.

Just go to the web site build it solar.com and you get plenty of information.

The bead thing seems to be the current 'hot thing' around. İ have seen it on a couple of other blogs and one site dedicated to it. As others have pointed out it is a lot of work to make a backwards step.

Hello Fredart,

I think the use of beads will be a waste of time and money due to the perceived recipient surface area issue as previously discussed by others in this Blog. May I suggest that you instead try Evacuated glass tube collectors with a copper pipe heat tube installed inside of them. I'm currently building 52 of them for my system to heat the house via the existing Hydronic System + to produce Domestic Hot Water. These tubes are highly efficient, but very expensive brand new. As far as I know, these types of tubes are state of the art and the most efficient energy efficient in terms of radiant energy capture and transference.

However, you can buy US Government Surplus tubes (NASA and USDOE test bed surplus) on Ebay for a cheap price (less than $25 USD apiece in the US.....more if elsewhere due to freight costs and insurance). I've tested some of my tubes just this past month in the weak May sunlight, and as a result I found that I was obtaining heat bulb temps of around 350 degrees F without the tubes being connected to any heat transference device like a water-jacketed heat transfer manifold. Anyhow, if you go this route just make sure you buy the tubes that were manufactured w/ the gold film on the inner tube and that there is a vacuum present between the two glass tubes.

You can also artificially boost the capture radiant energy from the sun by installing a fabricated Linear Fresnel Lens (curved or flat) that is made of Acrylic. At a minimum, you most likely will boost the captive radiant energy by a factor of no less than 8 Suns......and ideally, up to 15 or more Suns. Beware, these lenses are not cheap! There are several companies worldwide that manufacture these lenses....in Japan and the UK.

Just a little guidance.....Suns up!

Is water the best medium to collect heat?

Yes, to store heat maybe, but air is easier and cheaper to transport
and, can be passed through an exchanger, to heat the water.

Would a glass panel, (sheet) fixed about 100mm above a black/dark roof surface,
draw air under it's open base, be heated as it rises to the apex, to be extracted
via a trunking at the apex by a fan, directing it to a heat exchanger, work better?

I have thought of doing something like this for a while, being always put-off
by the £xx thousands of pounds asked for by the certified installers.

I am inclined to try a simple, if less efficient (?) air system, than a seem (to me)
an "over-complicate" water / pump / piping system. What do the team think?

jt.

I'm a very simple fellow....

İ am all for solar thermal air heating - have seen several home made units on the net that worked quite well. Water heating for space heat is more difficult as you need higher temps - someone mentioned a vacuum tube system that would certainly take of that though.

About 50 years ago, on the island of Petit St. Vincent in the Caribbean, there was a hotel with a solar still which provided freshish water from sea water by means of a solar still. This was essentially a shallow swimming pool of salt water covered with a plastic sheet which deposited condensed water into a peripheral gutter.

It was decided to increase the evaporative surface by floating black plastic beads on the surface.

I think that these beads were un-expanded polystyrene beads. This is the raw material used to make steam-expanded polystyrene insulating sheets and coffee cups.

I have a vague sense that this idea was not successful. Maybe it was algae as has been previously suggested. Anyway, you could check it out. It's cheap.

why not just put black dye in the water?

For environmental and practical reasons: it would no longer "switch itself off" and overheat when the water stops flowing. Could be done though, in a different configuration i.e. absolutely closed circuit. Take a glance at the video (mentioned in my comment #8).

when flow stops.. just cover it up. or turn away from the sun, if using solar tracking system. will check video.

That would do it!!