Solar collectors are a modern solution that allows the use of solar energy to obtain heat. It is primarily used to heat utility water. However, for the entire solar installation system to operate effectively, it must be properly constructed and prepared.
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How to choose the cross-section of a solar pipe?
As in every system, in a solar installation the fluid that is the energy carrier must be transported from the collectors to the tank, exchanger or other target location. Appropriate pipes are necessary here to ensure the tightness of the system and to be resistant to the action of glycol that is poured into the installation .
The solar pipe is most often made of stainless steel , which is highly resistant to harmful factors and mechanical damage. Copper pipes are also a good solution. The exceptionally high temperature of the systems, large temperature fluctuations, and high pressure mean that the products used to make the installation must be exceptionally durable.
In practice, pipes are available in various variants, and the most important parameter to consider when buying is the diameter. In addition, attention should be paid to the material from which the product is made. In the case of copper pipes, models are available in hard and soft versions. The former are usually sold without insulation, which must be purchased separately, while soft pipes are protected by a single or double layer of insulation. It is worth noting that copper models are used only when their diameter does not exceed 42x1.5 mm.
A major advantage is the use of stainless steel pipes in the installation. They are characterized by a corrugated structure, which allows for compensation of thermal expansions. For optimal operation, steel pipes are protected with an appropriate layer of insulation, and its thickness depends on the individual needs of the project being implemented. Steel models are available as mono and duo solutions, with the latter always equipped with a factory connection to the temperature sensor.
Correct flow of the medium in the solar installation
Incorrect selection of the solar pipe diameter will cause a number of problems, but it should be remembered that both too small and too large pipe diameters are very problematic. If the cross-section is too small, a situation occurs in which the heating medium encounters high hydraulic resistance and its flow through the system is inadequate for the needs of effective heating.
The reduced flow rate also causes the glycol to be raised too little by the circulation pump . As a result, the efficiency of the entire solar installation system decreases. The lack of effective heat transfer causes the heat losses generated by the solar collectors to increase. Instead of going to the tank, the energy is released into the environment. A major problem is then the operation of the circulation pump, which consumes significantly more electricity. It needs more power to raise the heating medium to the required level. An incorrect, too small diameter of the pipes causes them to wear out faster. This leads to faster erosion of the internal surface , especially if copper pipes have been installed in the system.
If the solar pipe is too large in diameter, then the fluid flow rate will be too low during operation . In such a situation, there is a risk that air will accumulate in the installation, and when the system is filled with air, it will block the proper flow of glycol. Additionally, there will be problems with heat loss to the environment , and the losses from the external surface of the pipes will be large.
The flow rate of glycol in the system, in order for it to function properly, should be between 0.40 and 0.70 m/s. The optimal pipe diameter is determined individually, taking into account primarily the needs of the given system. Determining the total aperture area is therefore necessary to indicate the best cross-section, which is why this task should be entrusted to specialists.
For example , if the system consists of five flat collectors, in which the absorber surface is 1.8 m2, it is possible to install a pipe with a diameter of 16, and the flow rate will be equal to 0.70 m/s. At the same time, it is worth noting that in such a variant the maximum recommended speed of the glycol heating medium must be achieved, therefore a better solution will be to increase the cross-section to DN20 - a larger diameter will reduce the glycol flow rate, but the value will still be within the established range. The installer will perform appropriate measurements, taking into account individual needs and the construction itself, because in each system, apart from the piping, it is also necessary to use additional elements, such as gaskets , tees , elbows and others. Only optimal project development and professional implementation help to optimally prepare an effective and economical installation .
Solar pipes at the Onninen wholesaler
Onninen's offer includes high-quality solar pipes , such as the double inch pre-insulated steel pipe Duo Solar in black . The product prepared by the armacell brand has all the necessary certificates. Prepared for use in complete systems. The product is basically two corrugated steel pipes, thanks to which you can easily and efficiently connect solar panels to a hot water tank, because each pipe has a specific function - supply and return. Due to the specific requirements of the system, the pipe is adapted to work at temperatures of up to -50 degrees, at a maximum pressure of 16 bar.
An alternative solution is the SOLAR PRO solar pipe with rubber insulation and protective coating . This model is made of acid-resistant stainless steel. A big advantage is the wide temperature range in which it can operate effectively. According to the manufacturer, this is from -40 to +150 degrees Celsius, although the maximum value is even higher, 175 degrees C. Rubber insulation provides excellent protection against UV radiation, while also having a low thermal conductivity coefficient.