quinta-feira, 31 de maio de 2012

Solar Food Dehydrator

Many of you are dehydrating food in order to preserve it. In a conversation recently with the Shibaguyz, I promised to post pictures of my solar food dehydrator. I bought it about fifteen or sixteen years ago from an advertisement in Earth Garden or Grass Roots (I can't remember which). It is called a Solar Safe and is manufactured in Euroa; the address is RMB 2317 Euroa, Vic 3666. I do not know whether or not they are still in production nor how much they would cost.

I'm thinking that a handy person could probably construct one of these. In deference to the intellectual property of the person(s) that designed it and also because they have a "Patent Pending" sign on the side, I'll just list a few of the measurements. You'll need to work out a detailed design for yourself if you want to make one. There are plans for various solar food dehydrators on Mother Earth News, but all are different to mine, so I thought I'd add it to the melting pot.

Here is the front view. The cover appears to be polycarbonate (laserlite) sheeting. It is held down by battens on the top and sides and by capped screws along the bottom. It seems to be pretty good at keeping any moisture out. There is an overhang of a few cm at the bottom, which shields the bottom vent.

As you can see, the bottom of the drier and the back panel are covered internally with black plastic.

This is the side view. Again, the side is covered with polycarbonate sheeting. The height of the side panel is 24" (61cm) at the apex and it is 28" (71cm) long on the base.

Because of the triangular side design, shelves are staggered and so each shelf gets a bit of direct sunlight. Food placed on the top shelf tends to dry fastest, so I often shuffle the food upwards, as the top layer dries.

I forgot to take a photo of a shelf, but they are basically rectangular wooden structures with plastic mesh attached. The bottom three measure 22" (55cm) x 12" (30cm). The top shelf is 22" x 8" (20cm). The shelves rest on wooden runners and are easily removed or fitted through the open back door.

Here is the back panel. It is 24" (61cm) high and 25" (64cm) wide. It consists of a top meshed part (the back vent), a door and a bottom support. The back vent is about 2.5" (6cm) high and extends across the entire back.

The door is held in place by wing-nut type catches. There should be a knob in the centre top of the door, but mine has fallen off (note to self: replace knob before next drying season!).

Here is a close up of half of the back vent.
Here is a close up of half of the front vent. It is about the same size as the back vent, only positioned at the lower front, under cover of the polycarbonate sheeting.

The principle employed in this drier is that the air is heated by virtue of the sun and the black plastic. Because warm air rises, cool air is drawn in at the bottom, warmed, and expelled at the top. This creates a nice air current for drying the food.

The dehydrator is virtually vermin proof, as everything is fairly tightly fitting. The only issue I have ever had is with ants, but that was solved by having a moat around each leg, so that the ants can't crawl up. The way to do this is to get four average sized tin cans (or similar) and turn them upside down inside larger tins cans (or ice-cream containers or similar). Rest the dehydrator on top of the four smaller tins and place water in the larger vessels. This way, you have water which the ants cannot cross and the wooden legs (which are about 6" (15cm) long) are not sitting directly in water.

Hopefully this is enough to get you started on your own solar dehydrator project. I like this design because it is simple and compact and can be carried by one person. Food dries in a day or two (depending on original moisture content, thickness, etc) and of course, it uses free energy and lowers our impact on the planet.

love and light
Fonte - naturewitch

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