BaysideBob wrote: > > Speaking of "survival", does anyone have any info on distilling fresh from > salt? > I saw a website of a fellow who did it at the rate of one part fuel to one > part freshwater distilled, not too effecient and no details as to how it was > done. Or perhaps solar stills? Basically, to get the efficiency up, you have to make good use of the heat from the fuel by pre-warming the water entering the still pot with some of the "waste" heat from the condensing phase. That is SOP on the oil patch or in a refinery, where every calorie of waste heat is a few millicents lost, and every food Calorie is a penny lost. A practical thing when the operation is stationary and will be used endlessly. Some arid countries do this with sea water. Invariably, they have cheap fuel -- or, as in the Middle East, the fuel is "free:" in Saudi, natural gas has no market, so they just flare it off at the well head. At that price, it pays to make fresh water from salt. For we energy-poor sea kayakers, using a large surface-area unit which exploits the (low-grade) heat from the sun, and a condensing water source of coolness (read: sea water as the condensing fluid) is the only really "efficient" and practical method. Drawback: can't be done on the rolling deck of an enroute sea kayak. Can be done ashore, with some setup time. Good to know for a survival situation. I think NOLS has published some methods using black plastic as the solar collector for the heat. A Web search should reveal some tested techniques. -- Dave Kruger Astoria, OR chemist *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Tue Feb 01 2000 - 19:43:51 PST
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