Solar Food Dehydrator

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Solar Food Dehydrator

Post by Admin on Sat Mar 10, 2012 11:02 pm

Solar Dehydrator

Today I spent some time in Google sketch up drawing out the designs of our Solar Dehydrator.
I do not have an exact parts list yet but this will give you a very good idea of what it looks like and how to build it.

This solar dehydrator works by convection draw.
The principals at work are thermo dynamic and are the same principals at use in our convection draw cooling system for our Earthships. In this case we are moving hot air and not cold air. Oh and this thing moves a whole lot of hot air.

This first picture is of the basic box. The box is a 4′x4′x8′ box. Plywood or ply siding walls with 2″x4″ construction.

Here we have the box with a false wall added. The false wall is 1′ deep and has a 1′x4′ hole at the bottom of it.
On the top of the box directly over the false wall you will cut a hole for your exhaust. This should be a 10″ or better exhaust vent. Next you will see a hole cut in the wall opposit the false wall. This is your air intake. This will be sized to your matterials. I will be using 2″x6″x8′ for the air ramp intake. so my hole will be 6 inches plus room for plywood and glass.

The vent pipe should be metal and 10″ by 6′ tall. The taller you go the more draw you will have. You will paint the vent pipe matt black. You want it to absorb as much sun light as possible.

In these pictures we have added the air intake ramp. This should be made of 2″x6″x8′ frame with a ply wood back. You will paint the whole interior of this matt black and cover the box with glass. At the base of this box is where your air intake will be. You will need to cover this with a good screen. You do not want anything but air to get into this.

Next we add the racks. The racks will be made of 1″x1″s and screen. They will be roughly 3′ square. Secure a row of 1″x1″s to each side wall so that the racks have something to rest on. Spacing is up to you. With a 6′x3′x3′ drying space you should be able to get in a rack at least every 6″ giving you 12 racks with 9 sqft of space per rack for a total of 108 sqft of rack space. You may be asking yourself will this thing actualy dry that much food? The answer is be careful on a sunny day not to burn your food!

Last we need to add a door.
As you build, caulk the seams. You want this to be as air tight as possible.
Your final product should look close to this. You are going to want to weather proof the outside and paint the main body of the box white.

The air flow heats and rises in the air ramp intake, then heads down through the food as it moves, drawing the moisture down. This is the way air would move as it comes in contact with moisture because the air will cool and settle. The black vent pipe causes a serious convection draw. It will pull the air right through the whole system.

Comments are welcome and I will answer any questions anyone has. I will be building another one of these in the next few months. I will post it when I do.

Capt Kirk


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