After reading a great Instructable on building a solar water bottle heater by robbtoberfest, I decided to try to design a system for backpacking and heating up water for use in dehydrated food. It appears the key to the temperature of the water is not so much the outside temperature, but the amount of sunlight. The original method used a 3 bottle system. I compared various alternatives including a 1, 2 and 3 bottle system.
With robbtoberfest's original 3 bottle system I could get water to about 135 F in 3 hours. If a larger outside bottle is used (a juice bottle), the temperature could reach about 150 F. If I used a 2 bottle system with a cut out half of a car window shade reflector, I could go as high as 196 F. Unfortunately, I think the water may have boiled and it melted and deformed the bottle.
I also have changed the outer bottle to type of PET with a wide mouth so that you don't have to cut it open and tape it after each use. You just screw the two halves together.
Although I would like to use just PET (like soda bottles) bottles due to their low weight and abundance, I now use HDPE (like the cloudy Nalgene bottles) for the inner bottle. (Lexan bottles may release estrogen like substance so I avoid those.) I also will investigate using a lighter reflector - mylar with a collapsible plastic frame.
A 3 bottle system may insulate the bottle better when the weather is cold. I will test this later.
SEE THE COMPLETED INSTRUCTABLE ON HOW TO BUILD A VERY EFFICIENT ONE BY GOING TO THIS INSTRUCTABLE LINK: www.instructables.com/id/Solar-Water-Heater-for-Backpacking-Using-Water-Bot/
Solar Water Heater for Backpacking
With robbtoberfest's original 3 bottle system I could get water to about 135 F in 3 hours. If a larger outside bottle is used (a juice bottle), the temperature could reach about 150 F. If I used a 2 bottle system with a cut out half of a car window shade reflector, I could go as high as 196 F. Unfortunately, I think the water may have boiled and it melted and deformed the bottle.
I also have changed the outer bottle to type of PET with a wide mouth so that you don't have to cut it open and tape it after each use. You just screw the two halves together.
Although I would like to use just PET (like soda bottles) bottles due to their low weight and abundance, I now use HDPE (like the cloudy Nalgene bottles) for the inner bottle. (Lexan bottles may release estrogen like substance so I avoid those.) I also will investigate using a lighter reflector - mylar with a collapsible plastic frame.
A 3 bottle system may insulate the bottle better when the weather is cold. I will test this later.
SEE THE COMPLETED INSTRUCTABLE ON HOW TO BUILD A VERY EFFICIENT ONE BY GOING TO THIS INSTRUCTABLE LINK: www.instructables.com/id/Solar-Water-Heater-for-Backpacking-Using-Water-Bot/
Solar Water Heater for Backpacking
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I would strongly advise against aluminum. It has become a major suspect for Alzheimers and I suppose if not so much of our dishes were made out of it this would have been made popular in a much broader sense already.
As rule of thumb, it might be best to not use anything that doesn't occur naturally on the surface of the earth. Clay, Glas, Wood, Stone, you get the idea.
I would also point out that fired clay and glass are not naturally occurring, and many glazes for ceramics are far more toxic than aluminum. I believe that diversification and moderation are key. Don't use only one type of container; try to thoughtful about what you use; discard (recycle) items that are showing signs of wear.
http://en.wikipedia.org/wiki/Rgb
Reflected light as in "pigments".
I GAVE YOU 5 STARS, I THINK ANYONE THAT PUTS SOMETHING ON FOR FREE SHOULD GET 5 STARS GREAT jOB!!!
Using a metal bottle solves the issues of contaminants leeching from the plastic.
regards
Graham
it's true that glass would be heavier, but the increased mass, and the insulative properties might mean hot, hot, heat.
My experience with re-sealable bottles is as follows. The most likely point of failure on a screw top glass bottle is actually the inside-threads on the metal lid. They tend to stop holding tightly after a short period of usage or from a single over-tightening. Beer bottles with the traditional pry-off crown cap are more likely to fail than anything in the capping mechanism. Yes, it takes a tremendous amount of pressure to burst a beer bottle due to over-pressurization, but that's not terribly difficult to produce if you were to make a miscalculation in the amount of priming sugar to add to a batch of beer. When they do rupture it can be a dangerous situation; they call them bottle grenades for a reason!
PET it is then. At least, until DuPont comes up with the next big thing in plastic bottles that is...
http://www.webstaurantstore.com/vacu-vin-white-wine-saver-vacuum-pump-set-with-1-stopper/9180854250.html?utm_source=NexTag&utm_medium=cse&utm_campaign=NexTag+Campaign
why doesn't anybody use metal, plus some types are better conductors of heat anyways, but i get what you guys saying about the inner bottle being plastic to insulate a bit better.
but plastic poisoning!!!!!! =( =( =(
I had the large size galvanized automatic waterer. I took a rubbery type heat tape, the kind you keep your pipes from freezing with, wrapped it around the outside part of the waterer and duct taped the whole thing down. I wrapped it so the end with the plug was at the top and left enough to attach an extension cord to.
Then I suspended the waterer and ran the extension cord up the cable holding the can. The heat tape thing has an automatic sensor that only turns on if the temperature drops below a certain amount. I never had to chip water and the hens had drinkable water even down to 0 degrees. It kept the metal conatiner just warm enough to keep the water flowing.
Hope this helps.
I cook rice in my solar oven in a canning jar painted black. What principles could feasibly be adapted (non-emission plastics, lightweight materials, portability, etc.) for a hiking situation from this?