Grade 11 students and equipment to turn saltwater into sweet

The teachers and students in Ben Tre have just succeeded in creating a device to purify salt water into fresh water by using solar cells.

In the face of severe drought and saline intrusion in the Mekong Delta, many households do not have access to water, teachers and students of Nguyen Dinh Chieu High School (Ben Tre City, Ben Tre Province) have taken pictures. the idea of ​​filtering salt water into fresh water using solar energy. The study was carried out from May 2015 until now.

There are many ways to filter saltwater into sweetness like desalination, nanotechnology, but the group chose distillation by taking advantage of solar energy, in order to save natural resources, protect the environment and contribute to fighting Climate Change.

The device turns saltwater into sweet.(Photo provided by the research team).

Mr. Truong Huu Dung said, the device consists of three parts: the salt water boil is created by vacuum glass tube capable of absorbing 93% of sunlight, thereby turning the solar energy into boiling energy. salt water. Transparent tubes allow light rays to pass through and reflect at least. The inner tube is coated with a paint absorbing layer by spraying technology so the absorption of solar radiation is high. Below is a layer of stainless steel troughs to help absorb more sunlight.

The second part is a insulation bottle made of T-shaped thermoplastic resin. The group designs two plastic containers with high temperature resistance, can be interlocked, and has a gap in the middle to fill the insulation. .

The third part is a distillation tank made of 8mm glass, made of 2 layers. The glass outside the transparent rectangular box allows light rays to pass through; The smaller inner layer, shaped like a house with a black painted surface, absorbs sunlight from a stainless steel parabolic pan underneath.

In between these two layers of glass are vacuumed to retain heat. A stainless steel plate is placed on the top of the "roof" containing cool salt water to cool the condensed steam on the underside of the "roof" and flows downward into the pipe out, this is fresh water. Part of the salt water used for cooling has a pipeline through the insulation tank and has a locking valve when needed to open the water.

The bottom parabolic frame has a conical shape, made of iron and painted with lightning. It is mounted on a rack system that can rotate in the direction of the sun. The group used stainless steel with good gloss, good light reflection and no oxidation to make a parabolic pan.

The team hopes this device can help people in the Mekong Delta to have fresh water during the dry season.

With the above design, the user will pour saline water on the top of the distillation tank, then open the water valve that will flow through the insulation bottle, down the vacuum tube to absorb heat from the hot sun to converse with the water. colder in the insulation bottle (the proportion of hot water is lighter than cold water so hot water floats upward, cold water sinks). At this time, the water in the insulation tank heated up (highest in the range of 75 to 85 degrees C), the hot water through the lower part of the distillation tank continued to absorb heat from the parabolic pan, evaporation (fresh steam), condensation. The bottom of the stainless steel sheet flows down the plastic pipe to the fresh water container.

Nguyen Tan Loi said that the biggest difficulty is using solar energy. Because when the heat is lost, it will be lost in two parts, the insulation bottle and the distillation tank, so the group took a long time to overcome. If put into use, the machine will cost less than 2 million, reaching 6 liters / day. The group plans to continue to create new versions with more modern improvements.