Solar Thermal collectors

Solar thermal collectors are responsible for absorbing solar energy and transferring it to the fluid inside. These collectors are different from solar panels. In solar panels, electricity is produced. But in solar heat collectors, hot water is produced, which is stored and consumed by transferring it to tanks or heat exchangers.

In general, there are two types of solar collectors:

1- Flat solar collectors

2- Vacuum tube solar collectors

Solarkar company produces both types of these collectors.

دانلود کاتالوگ کلکتورهای خورشیدی صفحه تخت سولارکار
دانلود کاتالوگ کلکتورهای خورشیدی لوله خلاء سولارکار

Learn more about solar thermal collectors:

: ​Flat Plate Solar thermal Collectors

The working method of flat collectors is that the sun's rays pass through the glass and shine on the surface of the absorber and heat it up. Water or heat transfer fluid is inside the communication pipes connected to the plate and is heated by this means. In fact, after being absorbed by the screen, the energy of the sun is transferred to the heat transfer fluid and by directing it to the heat exchangers, the energy absorbed from the sun is transferred to the utility systems.
The glass on the collector creates a greenhouse in the collector chamber and raises the temperature inside even in winters.
The insulated body of the collectors also prevents the loss of absorbed heat.
The most important factor in the quality and efficiency of solar heat collectors is the quality of the absorber plate. These plates are usually made of copper or aluminum. The type of surface coating should be such that it has the maximum absorption of the sun's radiant energy while at the same time the minimum heat emission. This type of surface coating is called selective coating. The highest quality absorbent surfaces are obtained in titanium oxide layering technology (Tiox sputtering). This technology was developed in Germany and is known as blue coatings. Two companies, Tinox and Alanod, are the main manufacturers of absorbent plates with this method in the world.

Another important parameter is the way to connect the fluid transfer tubes to the absorbent plate. The type of this connection plays a significant role in the quality of heat transfer. This connection can be mechanical bonding or ultrasonic or laser welding.

The highest quality has now been achieved in laser welding, which allows the connection of thin aluminum plates and copper pipes without surface damage.

Flat plate solar collectors are composed of the following components:

1- Glass
2- absorbent plate
3- Communication pipes
4- Body insulation
5- Frame

Vacuume tubes :

Another important advantage that vacuum tubes have given to the solar heating industry is the extremely low temperature loss of zero. In such a way that the problem of water freezing inside these pipes at minus 20 degrees was eliminated and the need for antifreeze and insulation was practically eliminated.
To produce this product, permanent melting furnaces and glass surface coating devices are needed. Because of the need for high investment, the mass production of this product was actually concentrated in China, and despite the fact that its technical knowledge was related to Germany. , but its development and commercialization was realized in China. ​​​​​​​​​

Vacuum tube collectors consist of two glass tubes inside each other, which creates a relative vacuum in the space between these two tubes. By coating the outer surface of the inner tube with a layered combination of copper, aluminum and steel nanoparticles, an absorbent surface is created. Vacuum creates a very good thermal insulation. Therefore, when the water inside the tube is boiling, the outer surface of the tube is cold. Also, when the air surrounding the pipe is below zero, the water inside the pipe does not freeze.

The advantage of vacuum tubes is cheap price and no heat loss. Its disadvantage is its short lifespan compared to flat plates and its greater vulnerability.

Thermosiphon low pressure water heaters are made from vacuum tubes. Also, by adding a copper core and aluminum fins inside it, heat pipe collectors can also be made, which can be used in the production of high pressure vacuum tube solar water heaters.

With vacuum tubes, a variety of vertical and horizontal (propeller) collectors are made, which can be used in high capacity spa production.

The use of vacuum tubes in solar heating is a valuable invention of scientists in the field of renewable energy in recent decades. With the supply of vacuum tube collectors, it became possible to make inexpensive solar water heaters. Because the raw material used in the production of this product is glass, which is much cheaper than expensive metals such as copper and aluminum.