Dessicant for Drying Fruit. (Dry in Solar Cooker to Recharge)

These should help...

http://www.motherearthproducts.com/desiccant.htm

http://www.sciencedirect.com/science/article/pii/S1876610213009909

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

If you are going to use a desiccant, I would look to silica gel. Not the cheapest but very easy to regenerate, I've even used a microwave on smaller amounts.

Thanks, I am keen on the calcium chloride. I like it because it is cheap. Want to concentrate on it. Below are the melting points and decomposition points from wikipedia (which is tabulated a little oddly and the last stuff (hexahydrate) sounds incomplete). I like that it turns to a solution when it is completely discharged. And how it is exothermic as it absorbs moisture. If it is possible to reliably make large crystals in a solar cooker, it could work not just for drying fruit but also as a supplemental heat source in a greenhouse. All you got to do is have a tub of it, and a fan, and pump the greenhouse air through it, The calcium chloride absorbs water and maybe heats the air at the same time? and (hopefully) you get a drip of calcium hydroxide solution as things progress. (without a caking that prevents air flow). Then you just recrystalize the calcium hydroxide in the solar cooker on sunny days. This sounds like a thing that could make a difference in sunny northern climates. Because in those places a greenhouse can become moisture laden ideal for disease and the drying of the air might clean up that type of problem.

772-775 °C (1,422-1,427 °F; 1,045-1,048 K) anhydrous^[4]

260 °C (500 °F; 533 K) monohydrate, decomposes 175 °C (347 °F; 448 K)

dihydrate, decomposes 45.5 °C (113.9 °F; 318.6 K)

tetrahydrate, decomposes^[4] 30 °C (86 °F; 303 K) hexahydrate, decompose

That would be my second choice. However, do some research on the rejuvenation, it's not quite as simple as silica gel. If it gets too wet, it can end up as a hard lump.

Try this rednek solar drying method:

Place the sliced apples,pears,etc. in the back windshield of a car,preferably of a dark color.

During the daytime,they will dry gradually, at night they will distribute the moisture

evenly.

The next day, the cycle continues.

This has worked for years with near perfect results.

Try it,you will see.

Pay no attention to the inquisitive looks of passers by.

If you seriously want to consider calcium chloride, check out this link from Dow-http://www.prog-univers.com/IMG/pdf/CalciumChloridHandbook.pdf (sorry, won't hyperlink!).

To use it you need a sealed, vapor tight drying compartment. Otherwise you will not be able to lower the humidity to the point of usability. Secondly, you need to determine the operating temperature/RH needed to desiccate the fruit effectively and correlate that to a calcium chloride hydration level, which will be the cutoff point of use- in my opinion, not likely to reach saturation. Thirdly you need to calculate the energy input needed to regenerate the calcium chloride from that point back to a usable restarting point, keeping in mind that this is significantly more than simply boiling that amount of water. Finally, you have to consider how to handle and store it as needed in between these points, especially as it can cake up (note that flakes give you the best surface area ratio and thus speed of absorbency), and if you intend to dry large amounts and store it for use at a later time the storage has to be extremely vapor tight as well.

So it definitely isn't impossible, but you have to determine the practicality!

Thanks very much for the answers. I did my solar cooker stuff several years ago. All sorts of weird stuff. I had dripper trackers and clam shaped reflectors and other things too but how do you solar cook when you work days? It is impossible so my half assed designs ended up pretty much useless. Last spring I got the earliest peas in Victoria with the "drip-wall delta" and that was just using a drip of water to collect heat from the back wall of a greenhouse and send it into the soil under the plants for nighttime frost protection. It was never more than 200 watts but it sure made a difference. So, maybe this winter, I can rig up something to use a desiccant to dry the greenhouse air at night and simultaneously warm it too. At night you get condensation on the roof of the thing and presumably that means that it is losing lots of heat through the roof. But if it is dried in the desiccant chamber, maybe the heat is "lost" there instead. It would still need a fan of course but that is tiny energy compared to condensation energies. Thanks Brian