Air2O

Air₂O is a solar powered dehumidifier designed by 5 seniors at The Citadel to help with humanitarian relief. It is designed to collect water and fill any jug through a 3' garden hose, it can easily be transported by 2 people.

It works by using a "Peltier" chip that cools a heat sink which is in contact with copper tubing filled with water that act as a natural convection loop. This condenses water from humid air that is pulled though the chamber via a fan running perpendicular to the coils. The water then drips off the coils to the bottom into the water storage container.

Unfortunately due to the Coronavirus construction was not complete.

In order to build the dehumidifier you will need:

• 1 Water/Dust proof computer fan
• 1 Thermos-electric cooler by Adafruit
• 4 sheets of 24x48x1/4 HDPE
• 1 50 ft roll of FoamSealR 5-1/2" insulation
• 10 ft of 1/4'' OD Soft Copper Refrigeration Coil Tubing
• Cold space 3D printed casing and fan cover
• Mesh screening
• 3 Brass Fitting 1/4" OD
• 5 Aluminum Angles 1.5x1/16x96"
• 100 1/4"-20 Stainless Steel Bolts, Nuts and washers
• 1 3ft water hose with US standard pipe fitting
• 1 Industrial size funnel

Tools

• 1/4" Drill bit and drill
• Jigsaw
• Table saw
• Drop saw
• Miter or hack saw
• Files
• Ratchets with 1/4" heads
• Hot glue gun

After inventory, the first step is cutting the stock into the correct dimensions.

HDPE

Cut 4 sheets of HDPE cut into six 24x24" squares using the table saw; they most likely need to be squared off as they come roughly cut. 6 squares should be made; 4 will need further cutting.

In one of the squares cut a circular hole of 3.5" diameter for a fan, in another square drill 21 inlet holes of 1/4" diameter in a 4 by 8 rectangular pattern that is centered on the sheet.

Set aside 2 squares; one will have 3 slots cut out centered to attach the cold space, the other will become the lid.

Aluminum Angles

To make the legs use the drop saw to cut two stock angles into 4' segments.

The remaining 3 angles will be cut into 2' segments also using the drop saw.

Angle Assembly

The frame of the device is entirely made from the aluminum angles cut in the prior step. The 4' segments will be the legs of the device, and the 2' segments will be the horizontal edges of the condensation box.

Assembling the frame will require a drill and 1/4" bit, screws, nuts, and washers to fasten the pieces together.

Measure 2' feet from the top of each 4' leg. Place the 2' segments perpendicular with the inside of the angles facing inwards. Fasten the angles at the corners to create a square. Do the same at the top-most end of the 4' legs with the remaining 2' segments to create the top edges of the condensation box.

Inserting the Squares

Insert the HDPE at the bottom and sides of the frame and attached using the same 1/4" bolts; there should be 4 screws per edge of the box. Make the squares with the fan cutout, and the inlet holes on opposite sides of each other. Leave the top end open for the lid.

To install the lid first four 24" angles are bolted flush with the top of the box to provide a lip for the lid to rest on and additional stability.

After this place the remaining 24x24" square on top and mark the outline of the bolts protruding on the lip onto the top square with a marker.

Then using a 1/4 in drill bit drill holes the length of the bolt into the HDPE, use a jigsaw to cut the holes to the edge allowing the top piece to fit.

For the corners of the top cut them at a 45° allowing them to clear the corner bolts. this should allow the top to fit on, however some more hand fitting may be necessary by using a file.

The heart of the Air2O system is the cold space which uses an Adafruit Thermo-electric unit (although any similar unit could be used)

The unit is housed in a 3-D Printed housing that is made in 3 components: a cold area containing insulation; a cradle that houses the unit, heat sink and tubes; and a hot space that fits over the end and protects the electronics.

Once the parts are finished 3D printing sand them until they fit snugly, then the cold space should have 4 1/4" holes drilled through it to mount it to the HDPE sheet with the 3 slits. Once aligned correctly it should be fastened to the sheet.

Cut down the heat sink to 1.6x2.4" in order to fit it to the Thermo-Electric unit. Then sand the inside of the cradle and the heat sink and connect them using a hammer and block of scrap wood. After checking the fit, remove to mark where the solid base ends then cut the walls of the cradle to allow the copper pipes to fit into the cold space.

Drill a 1/4" hole into the condensation box to allow the wires to pass through.

The convection loop implements three 1/4" diameter copper tubes bent, filled with water, and sealed.

To have the proper length of tubing, approximately 4' should be unspooled from the package. A mark should be made at 40" and then cut using either a jig saw or hack saw.

Once the cuts are complete, a metal file should be used along the edges of the cuts to create a smoother surface to allow for a more secure fit when sealed.

Measure and mark at 10" away from one of the ends of the tube. This will be the outer-most end of the radius at the tubes bend. Then, using a 2" diameter rod or pipe, center the marking and bend the tube evenly around without pinching the track. This will be the end that fits into the heat sink inside of the cold space.

For the remaining end of the tube, measure the half-way point and use this as the center of curvature to bend the tube around a 3 1/4" diameter rod applying pressure evenly.

Once both bends have been made, submerge the tube in water and secure the fitting to seal it shut.

Carry out this process for all three convection loop tubes.

The components to be wired to the breadboard are as follows: Weatherproof fan, Temperature Sensor, Peltier Refrigeration unit.

To complete this step the factory stranded wires, must be soldered or spliced to new single strand higher gauge wire to fit into the bread board. This should be done using wire strippers, soldering Iron, solder, assorted wire shrink and wire splices for 20 gauge wire.

For the temperature sensor, which requires 5 volt input voltage, use a voltage transistor and 22μF Diode to allow everything to be powered by the 12V 5W power source.

Cover everything that is exposed with electrical tape or weatherproof tubing.

The breadboard will be enclosed for safety.

Once all the electrical components are wired and the convection loop tubes are bent and sealed, the device can be fully assembled.

The fan may be screwed to the square with its respective 3.5" diameter hole cutout using the fasteners that were supplied in its package. After this, hot glue a generous size of mesh screening over the fan hole and inlet holes to protect from insects or contamination.

To fasten the cold space to the condensation box, drill four 1/4" diameter holes through the corners of the 3-D print box and line them up with corresponding holes on the HDPE square as well as the cutout slots for the copper tubing.

Next, feed the copper tubing from the inside of the condensation box through the slots and into the cold space. The tubes should fit snugly between the teeth of the heat sink. Then attach the fan cover over the cold space.

Lastly, drill a 2.5" diameter hole centered on the bottom face of the condensation box and insert a pipe fitting to screw on the hose. Make sure to apply caulk to reduce leakage. Insert the a funnel inside of the box leading to the hole drilled out for the hose. Insert the other end of the hose into the water container. Due to construction delays, a funnel, water container, and pipe fitting installation are not pictured above are not pictured here.

Place the lid on top of the box, and your device is ready to use!