I found this piece of info.

Glauber's salt is the chemical sodium sulfate decahydrate, sometimes used instead of sodium chloride in immersion dyeing, especially with wool and nylon. It is widely available from almost any company that supplies dyes at retail, such as Tie-dyed.com, PRO Chemical & Dye, Dharma Trading Company, etc.

Wishccr... Thanks for posting this. I had considered using early on and pretty much forgot about it. The one issue i have is that it's phase change occurs at about 90 F, which might be too high for effective heat capture in anything except a wall of tubes/plates as you mention.

In my freestanding GH, i don't want a wall of anything. I also was worried about using toxic materials and expense but looks like this stuff is considered non-toxic(?) and is cheap (saw one reference for $60 per ton - shipping may kill you though! lol). It has sources in Mexico and Canada so it may be available closer to home.

You might try contacting the fellow behind this page...

http://allanstime.com/SolarHome/index.html#5

There is a "contact" mailto link on the bottom left. looks like he built a home as least partially heated with the stuff in Utah.

Good luck and keep us posted!
Poppa

I thought I would rekindle this topic and question...
I have the same questions about using Glauber's salt. The most information I could find is that Dr. Allan stores it in 2 1/2 x36" black PVC tubes (I emailed him for info, but I have not heard back yet). Does anyone know the ocncentration you have to use? I have found a few sources for Glauber's salt online but I am uncertain how much to buy/ how much to add to water. What are the storage considerations? I have read that it can be corrosive- are there any concerns about storing it in PVC or handling it? Anyhow, any information on the practical uses of Glauber's salt are truly appreciated.
From everything I can find out about it it seems like it would be incredibly effective compared to convential passive solar thermal mass/ heat sinks like water and rock.

I'm not sure if this helps or not, but I use Calcium Chloride in my tractor tires for weight. It doesn't freeze, but if you have any leaks, it will rot any steel it contacts. I had to replace the wheels a couple years ago. One tire company refused to change them because of the Calcium. You also shouldn't come into contact with it...I hear you can get a wicked rash from it.

If you just doing heat storage, you may be better off filling your barrels with rocks and water. (rocks for mass and water to help pump the heat around if necessary) If you're concerned about freezing, add some rock salt (for a water softner) to the water. 10grams/liter will make it about the same as the ocean...and will get the freezing point down to 0C.

I am also quite curious about the use of phase change materials. The 90 degree phase change would work great in my setup but am having trouble finding out exactly how to use it. I did come across a link that discusses the products, but not their implementation. Anyone else had any luck recently?

I looked at the link mentioned in the previous post, but again does not discuss if all you put in the PVC tubes is the salt or if there needs to be some kind of mixture.

Here is a link that might be useful: Solar Heat Storage

Hiiiiii
I'm doing a project on Glauber's Salt And i've found some interesting informatiojn on it...
A) ther sell it for $6 a kilo in S.A
B) It gives off heat when combined with decahydrate or 10 parts of water
C) It is one of the most economically, cost-effective and eco-friendly option to insulation via other methods.
D) It can be heated using solar energy.
E) It gives off stored energy that can be used to heat or alternatively cool-down and object while hydrating and rehydrating itself.
F) It can be used to make artificial ice
G) It is most effective when placed between two insulators such as concrete.
H)It was discovered by a dutch german scientist named Johann Rudolf Glauber, and is also known as Sal Mirabilis which means Miraculous Salt.
I)It absorbs and releases its heat at a constant temperature which is what makes it so effective as a conductor and insulator.

Lot of problems long term with glauber's salt with it settling out of solution.

No it won't react with PVC, but PVC itself is an evil material. Use ABS (sewer) pipe instead. Cheaper and a lot easier on the environment.

All salts that are highly soluble in water are very corrosive to metals.

If you work out the BTU's needed, you're better off having a wall of black PEX pipe, and a tiny pump that moves water between that wall and a bunch of barrels you have under your benches.

Has anyone researched the bio friendly, less expensive, renewable and tested with better result PCM paraffin?
it seems that tiny encapsulated balls are being tested in wall board and brick with amazing results... the melt temp is lower as well and its not corrosive..I think this is huge?..couldn't we make a DIY tube or even use pop bottles?

Um....just a retired chemist stumbling across this thread.

The Glauber's salt should be used in SOLID form, not as a solution. The salt itself is just sodium sulfate with 10 waters as part of the solid crystal structure. Upon heating, the crystal structure breaks down, liberating the water molecules to form a very concentrated solution of sodium sulfate. When the temperature drops, the salt tends to recrystallize, releasing heat.

I don't know about the practicability of scaling the process up to a greenhouse wall scale (I've got a simple PVC free-stander, so it's out for me...), but the salt is certainly not "toxic" in the usual sense (remember, ingesting too much water will kill you!) and it would not attack PVC pipes.

Just based on supposition and observation in my own greenhouse (which gets both too hot and too cold), I would be most concerned about the kinetics of the process, i.e., how quickly would unstirred salt be able to make the initial phase change to liquid. I would not expect this to have much of an effect on the high temps of the greenhouse.

The other process, that is the recrystallizing, has a tendency to occur rather quickly once it gets going, meaning all of the heat is going to be released over a short period of time, although admittedly it will take it time to radiate away from sizable samples of the salt as might be stored in PVC pipes.

The only other issue that might be a problem is the potential for the liquefied salt to remain in that state even when the temperature drops, barring some kind of agitation (forming a supersaturated solution). Probably this could be forestalled by not using pure-grade salt but rather a (cheaper) technical grade. Or, you could just add a little dirt to each pipe!

Edit: looks like there is some reasonably current research into the practical problems associated with use of Glauber's salt for thermal storage: http://intraweb.stockton.edu/eyos/energy_studies/content/docs/FINAL_PAPERS/4B-4.pdf

This post was edited by steve_in_los_osos on Mon, Dec 3, 12 at 11:23

Hello Steve,

I realize your post is fairly old, but I am interested for the use of Glauber's salt as PCM for a rural development project.

I would like to contact you to explain you the project and get an honest feedback based on your personal opinion and homemade experience .

Is there a way to contact you through this website or another one? (I guess you are not so kin of leaving your coordinate to a perfect stranger and on a public internet forum with that, which I don't want to do either). If I could send you a private message somewhere, to initiate the discussion and explain you more about the project I am concerned with that would be great, and hopefully we could exchange more on the topic.

Best regards,

kthibault

Steve is active in this forum, try him there: http://www.cloudforest.com/cafe/gardening/

let us know if you find anything out.

Thanks a lot. I'll let you know!