It is worth clarifying the definition generator". Most have associations with gasoline or diesel generators built on the basis of an internal combustion engine. Of course, a do-it-yourself electric generator, an indispensable component of a car, and domestic power plants based on internal combustion engines are the most common of industrial designs. By definition, an electric generator is a device that converts various types of energy into electrical energy.
It will not be possible to use the energy of the atom at home (not the scale). The energy of the sun, wind, moving water and thermal energy (ICE) can be used according to one's strength.
Energy of sun
Solar battery- an alternative source of energy, not very powerful, but as an auxiliary (backup) system is already quite widespread.
It directly generates electricity, which is used to charge the battery. Of course, the power plant operates during the day and the power depends on the length of daylight hours. If you look at the insolation map of Russia, you can see that the duration of "sunshine" in half of the territory is from 1700 to 2000 hours per year, and in the southern regions (surprisingly, in Yakutsk) more than 2000 hours.
The efficiency of such batteries ranges from 9% - 25% of the declared power (depending on the type of cell), the most common models with an efficiency of 14-19%. If you do not go into the distinctive features of batteries, then in most cases, in order to get 1 kW of electricity, you need a panel with an area of 7 to 10 square meters. m. And now you can multiply by the number of hours of sunshine and get a good figure for annual savings ...
Another advantage of solar panels is the ease of installation. If you do not mount the system according to the “sunflower” principle, with rotation relative to the position of the sun, then the solar generator circuit is very simple.
Do-it-yourself electric generator: location of a stationary battery
for year-round operation it should be + 15 ° to latitude, for the summer months it is necessary to subtract 15 ° from latitude. Although for small systems it is possible to increase the power up to 50% by tracking the azimuth of the sun, since the deviation of the battery from the perpendicular of the sun's beam by no more than 15 ° gives 99% of helioradiation. The height of the sun need not be tracked, as it mostly falls within a 30° spread. The main thing is to take all this into account when installing the battery, for example, on a pitched roof.
In addition to stationary systems, you can buy or make a portable solar power station with your own hands, the power of which will be enough to recharge your phone or tablet somewhere in nature.
Do-it-yourself electric generator: wind energy
Wind is another environmentally friendly form of energy. But if solar energy is converted into electrical energy using photocells simply (from the point of view of the end user), then a wind power generator is a complex engineering structure that requires a whole range of work. In fact, at home, it is necessary to repeat the industrial installation.
The main components: engine - multiplier (reducer) - DC generator - battery charge controller - battery - voltage converter.
A wind turbine, or wind wheel, can be with a horizontally oriented axis and a vertical one. In the first case, this is the familiar (and most common) propeller design.
The vertical axis is wind turbines based on the Darrieus or Savonius rotor. Of the two, it is easier to make an electric generator with your own hands according to the second option.
Do-it-yourself power generator: each scheme has its own advantages.
Vertical-axis rotors have an efficiency of no more than 15%, but they also have a much lower noise level, and the Savonius rotor is quite simple from the point of view of a wind turbine. In addition, this type is less dependent on wind strength and does not require orientation relative to the direction of the air flow.
Horizontally axial modifications have a higher efficiency, but require orientation relative to the direction of the air flow (with a weather vane, or a shovel) and protection from strong winds. In addition, they are quite noisy, not only because of aerodynamic noise, but also mechanical ones are added (after all, the thrust bearing is “noisy”). Plus, to generate decent power, you need a rather large propeller size. But nevertheless, it is this type that is used in almost all industrial designs.
Now about the propeller, its dimensions and the number of blades. There is already a strictly verified, including empirically, table of the dependence of the power of the installation on wind speed, blade size and their number.
In order not to get confused with fractions, it is worth giving a simple layout with a wind speed of 4 m (the efficiency of the horizontal “windmill” is 0.35, the efficiency of the generator is 0.9, the gearbox is 0.8):
- diameter 2 m: 2 blades - 10 watts, 3 blades - 15 watts, 4 blades - 20 watts, 6 blades - 30 watts, 8 blades - 40 watts;
- diameter 4 m: 2 blades - 40 watts, 3 blades - 60 watts, 4 blades - 80 watts, 6 blades - about 120 watts.
In principle, as the diameter increases, the dependence is not quite linear, but gives a general idea. To get 500 watts at a wind speed of 4 m per second, the diameter of the wind wheel for 2 blades is 14 m, 3 blades is 11.48 m, 4 blades is 9.94.
Why is 4 meters per second chosen for the calculation?
As a rule, for central Russia, this indicator is the ceiling for average monthly values. For example, for Moscow and the region, the average monthly wind speed during 2012 generally fluctuates around 2.5 m/s. So when choosing a wind power generator, you should first take an interest in the statistics in the region, and then calculate whether it is worth straining, but if there are materials and components available, then why not make such a device.
Now about the blades - the most crucial moment. Sailing blades (like old windmills) have low efficiency, so you need aerodynamic blades, like an airplane wing.
You can even carve them out of wood, although many craftsmen cut a plastic pipe. But here there are nuances.
With a small number of blades, they are more difficult to balance and, moreover, vibrations are possible. A wind wheel with 2-3 blades is a high-speed one, the linear speed at a strong wind at the end of the blade can reach up to 200 m / s (the Makarov pistol bullet is 400 m / s, and the speed of the Saint-Etienne duel pistol of the 1835 model is 168 m / s ).
Plastic is a brittle material and can break at high speed in the presence of vibration. Therefore, it is best to use more “low-speed” wind wheels with 6 blades and a diameter of 2-3 meters to make a wind generator with your own hands.
And for their manufacture, take a PVC pipe for pressure water supply with a wall thickness of 4 mm or more. We cut out the blades, grind its edges and grind to obtain the required aerodynamic characteristics.
Then a "star" is made from sheet steel to assemble the propeller.
After mounting the blades, the wind wheel must be balanced. To do this, it is installed indoors on a vertical support with the axis level strictly horizontal and ensure that the wheel does not arbitrarily turn at any position of the blades, otherwise vibrations will occur.
Simultaneously with balancing, the position of the blades in space relative to the vertical is checked. For this, a fixed reference is used at the lower (or upper) point, determining the distance from this point to each blade when it is opposite it.
Unfortunately, without the use of a factory-made electric generator with your own hands or a DC motor, it will not work to make a wind generator.
Theoretically, it can be made, but why ... You can always find and buy a low-speed DC electric motor with permanent magnets and a voltage of up to 100 V. You can also install an automobile one, but it requires high speeds, and therefore a gearbox. You can choose a bike motor that has a maximum power of 250 watts at 200 rpm, at 24 V (enough with a margin).
After the propeller and the choice of the generator, it is necessary to make a frame with a reliable design (after all, the "airplane" on a leash).
Then make a swivel assembly attached to the frame and carrying the wind wheel and generator, with a brush current collector (if it is possible to pick up a factory one, it is better to use it).
And to protect against hurricane winds, install a movable side shovel with a spring tie on the hinge. In strong winds, there will not be enough spring force to align the shovel perpendicular to the blades. And the force of the wind will simply turn the blades along the direction of the wind. At normal flow rates, the spring will turn the blades perpendicular to the shovel.
It remains to assemble the structure: the propeller to the generator, the generator to the frame, the frame to the frame, the shovel is attached to it on the stretch, the frame to the rotary mechanism, the generator to the current collector, and already from it there are wires to the electrical part.
The whole structure is mounted on a mast.
The electrical part of the wind generator is the simplest: the diode bridge through the fuses and the voltage controller is connected to the battery, and the voltage is distributed further from it. Constant - for powering devices with the appropriate type of power supply. A voltage converter is used to obtain alternating current.
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