How to Build Solar Cells for Absorption Refrigeration How to Build Solar Cells for Absorption Refrigeration

What You'll Need
Wrench
Pipe cutter
Pipe wrench
Welder and supplies
Calcium chloride
Anhydrous Ammonia (in a pressurized tank)
2 10-foot Parabolic trough collectors with stands
3-inch black iron pipe (21 feet long)
2 1/4 -inch thick 4-inch square (or larger) steel plate
1/4 -inch black iron pipe coiled (21 feet)
2 Stainless steel valves
55-gallon drum (halved)
2 3-inch Black iron pipe caps
Condenser coil
Collecting tank
Reclaimed chest freezer or scrap wood or metal box

Solar absorption refrigeration is a great innovation for those who don’t have access to the electrical grid. It can keep vital vaccines and food cool by using solar energy. Small agricultural enterprises in remote areas can store their products longer until they can get it to market. There are two kinds of solar refrigerators. They use an absorption system, or they are connected to a solar panel which supplies electricity that runs the refrigerator’s compressor.

An absorption refrigerator uses solar heat as energy for the cooling system. This type of refrigerator uses a refrigerant with a low boiling point. Ammonia mixed with water is commonly used as the refrigerant. When heat is applied the temperature and pressure rise. When the heat is turned the pressure lowers and the liquid evaporates back into gas providing a cooling effect.

Step 1 – Set up the Troughs

Attach the parabolic troughs to their stands and place them end to end. Position these east to west and in the direction of the most direct sun, Fasteners will be included with the troughs.

Step 2 - Mount the Generator

Fill the steel pipe with with calcium chloride and cap both ends. Mount the pipe on the two parabolic troughs. This is the generator pipe.

Step 3 – Connect the Condenser

Connect the generator pipe to the condenser coil with a stainless steel valve. Place the condenser coil in the drum which is being used as the condenser tank.

Step 4 - Set up the Storage Tank

Weld the two steel plates to either end of the shorter 3-inch pipe. The other end of the condenser coil should be joined to the storage tank with another valve. All connections should be welded to be air tight.

Step 5 – Prepare the Ice Box

Insert the storage tank in the icemaker box (chest freezer or box). Put water in the condenser tank to make a bath for cooling. Place a couple of bags around the storage tank.

Cooling

Anhydrous ammonia in a pressurized tank evaporates into the generator via the valve. The generator pipe heats up and boil out of the pipe, In the condenser coil the gas turns to liquid. It drips into the storage tank below. At night the liquefied ammonia produces ice in the bags around the storage tank which keeps the icebox cool.

Warning

Ammonia is caustic and can be dangerous to work with. Be sure not to inhale it or get it near your eyes or nose. If there is a leak in the system water should be readily available to dilute the ammonia and for cleanup.

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