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Indirect, Throughpass, Solar Food Dryer - Open Knowledge — LiveJournal

Apr. 11th, 2004

08:33 pm - Indirect, Throughpass, Solar Food Dryer

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No survivalist bunker is complete without it's own indirect, throughpass, solar food dryer

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From:visgoth
Date:April 12th, 2004 02:13 am (UTC)
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Nifty.
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From:troyworks
Date:April 12th, 2004 04:51 am (UTC)
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I would think that a solar panel and battery with a real dehydrator would be more effective, I don't think they draw that much power since the heating is pretty low (I have a high end one and use it occasionally for various "raw" food dishes). It's not that complicated, but some things have to dehydrate longer and at a more stable temperature than solar/weatehr would allow.
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From:crasch
Date:April 12th, 2004 07:25 am (UTC)
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Hmm...I suppose it depends on what you mean by "effective". I think cost would be higher and energy efficiency would be lower with a photovoltaic system. First you have the efficiency losses converting light into electricity at the photocell, then the losses in storing it in the battery, and finally losses in converting the electrical energy stored in the battery back into heat in the dehydrator. It's much more efficient to use the sun's heat energy directly. A photovoltaic panel and battery system is much more expensive too.

On the other hand, a battery plus photovoltaic system could even out the temperature, and make it more uniform. It could dry during the night. Also, although the dehydrator's temperature and air flow can be controlled with vents, it would probably be more convenient with a photovolatic system. However, I'm skeptical that the additional cost would be worth the advantages.
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From:troyworks
Date:April 12th, 2004 07:45 am (UTC)
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I'm thinking effective from the primary purpose I'd use it for: preserving food, not cost of construction or possibly maintenance (as battries have a shorter lifetime than passive solar as presented).

my concern is out in the wilderness with a garden, that food supplies might be peaky (just killed a large game animal, had all the tomatoes go ripe at once etc) so that capacity would be better served dehydrating en mass with a elecrical system, the risk of losing food would be too high for me. Dehrating and different temperatures/durations make a difference in the quality of the food, it's nice to put a timer on a think set a temperature and forget it rather than havign to constantly go back and check.
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From:crasch
Date:April 12th, 2004 08:14 am (UTC)
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According to the article, most foods can be dried in a day or two. I don't think an electrical dehydrator would be much faster. The design they discussed could dehydrate about 50 apples at once. I don't think most commercially available home dehydrators have much more capacity.

It's true that drying temperature affects nutritional value, but I'm not sure it would be enough of a gain to justify the extra cost.

The main benefit of an electric dryer are reduced hassle: no time/frustration spent building it, easier controls, smaller space requirements. Perhaps you're right, and the reduced hassle is worth the extra cost, but electricity is precious on an off-the-grid system, and converting sunlight into chemical potential and back into heat again is quite inefficient. To resolve the issue would probably require some experimentation though.
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From:troyworks
Date:April 12th, 2004 06:27 pm (UTC)
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Your right in the time requirements, volume is relative, your right that a 9 tray might not dehydrate 50 apples at once, but 2-4 of them taking up the same space would.

The scenario I was suggesting: you just harvest something that now you have bushels of because lets say a large storm/frost is coming. Now you have bushels of all this food, with all the solar goodies on the fritz. Battery/chemical would be the only way to dry/freeze the things, unless one was into canning.

I suppose a hybrid system would be possible to gain the benefits and costs of both. The actual fan/heater is very small/simple. Forced with building one from scratch I might take this approach anyway of using an existing one as the plastic trays have lots of airflow and are already built, the rest of the housing wouldn't be as difficult to build except for the glass.
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From:chutzpahgirl
Date:April 12th, 2004 05:39 pm (UTC)
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There are lots of people who cook with solar power. Got any articles about that?
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From:crasch
Date:April 12th, 2004 06:01 pm (UTC)
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Yes--go back a few links in my journal for an article on making your own solar cooker.
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