The sun is the most powerful source of energy on Earth. Every second it sends us more than 80 thousand billion kilowatts. This is several thousand times more than all the power plants in the world produce. People have always tried to find a way to use solar energy for their needs. Already in the early Middle Ages, they knew how to make fire with the help of lenses, and nowadays the tank on the roof, painted black, heats the water and serves as a summer shower in the villages and cottages. By the way, it is the simplest solar collector - an uncomplicated and original device that allows you to use solar energy to heat water or heat. If you slightly improve the design, hot water is enough for all household needs, and for heating the house. For this you need to understand the principle of the solar collector.
How does the solar collector work?
The principle of operation of these devices is based on the transformation of radiant solar energy into thermal energy:
- the sun's rays heat the coolant circulating in the collector through thin tubes;
- heated coolant (water or antifreeze) enters the accumulation tank;
- in the tank it heats the water intended for household needs;
- coolant returns to the collector.
The principle of operation of the solar collector can be compared with the automotive cooling system - the excess heat is diverted from the engine running through the radiator and spent on the heating of the cabin. But, if it is important for a car, first of all, to take heat away from the engine, then when building a solar collector, it is necessary to effectively save it.
Advantages and disadvantages of using solar collectors
World scientists agree that the share of energy received from the sun will only increase and the following facts are given:
- the sun is an inexhaustible and free source of energy;
- the use of solar energy does not pollute the environment and does not contribute to an increase in the greenhouse effect;
- solar energy can be used everywhere, it does not need to be transported;
- modern scientific developments allow to effectively accumulate the received energy;
- solar collectors need minimal maintenance;
- the device of the collector is relatively simple and inexpensive.
However, scientists note and difficulties in the use of solar energy:
- collector efficiency depends on the level of insolation;
- installation of equipment will require certain initial costs;
- in winter, heat losses increase significantly.
Another significant drawback is the possibility of obtaining energy only during daylight hours.
Types of solar collectors
Above, we briefly described the principle of a double-circuit collector: a coolant flows through one circuit, and water flows through the second. This device can be single circuit. In it, the coolant is only water, which is subsequently consumed. A single-circuit collector is not suitable for use in winter, as water will freeze and sever the pipes.
In addition to dividing the reservoir into single and dual circuit, there are other generally accepted classifications. Thus, solar collectors are divided according to the principle of operation into:
Consider their structure and principle of operation in more detail.
Flat solar collector
This simple device resembles a sandwich with the following layers:
- aluminum frame with fasteners;
- heat insulation;
- absorbent absorbent surface;
- copper tubes;
- protective glass.
The absorber plate is painted black and provides maximum absorption of solar radiation, and special tempered glass covering the entire structure minimizes energy loss, creating a greenhouse effect and warming up the absorbent layer.
Flat solar collectors are simple in design, reliable, but have low efficiency.
Vacuum solar collector
Solar collectors based on vacuum tubes have a different principle of operation.
Unlike flat-type collectors, heat in vacuum collectors accumulate hermetically sealed tubes and heat collector. The glass surface of the tubes with a special coating effectively absorbs solar energy, which heats the heat carrier inside the tubes. Vacuum prevents heat loss by working as an insulator. Through the heat collector, the circulating fluid enters the storage tank to heat the water and then returns to the vacuum tube system.
Vacuum elements allow to provide a higher efficiency in collectors of this type compared to flat counterparts.
Aerial solar collector
Collectors of this type do not have high efficiency, since the air has a lower heat capacity. But they can be used all year round, since the air is not able to freeze in winter.
The design of the air manifold is simpler and highly reliable. Air-type manifolds can be used to heat residential buildings as well as industrial premises, vegetable stores, warehouses, garages, basements.
The device and the principle of operation of the air collector differ little from flat analogs: the system of copper tubes with coolant circulating through them replaces the heat sink panel with fins.
The device panel is similar to cellular polycarbonate. Air passes between the edges of the panel and heats up in the process. The heated air flows into the room, transfers its heat and returns to the collector. The panels are made of materials with high thermal conductivity - copper, aluminum, steel.
In the conditions of the Russian climatic zone with frosty winters, the air collector does not fully heat the house, but as an additional source of free heat can significantly save heating costs.
How to make a solar collector with your own hands?
The power of the solar collector is directly dependent on its area, but with the increase in the area will increase the cost of acquisition. In some cases it is much more profitable to make a solar collector from scrap materials. Its effectiveness will be relatively small, but spending on materials will not affect the family budget. Any homemade design will pay off very quickly if it is possible to prevent heat loss. The easiest way to do it at home is to make an air or flat solar collector.
First of all, you need to determine the place to install it:
- Panels need to be oriented strictly to the south at a certain angle, ensuring maximum insolation. The efficiency of the device will be higher if the angle of inclination of the panel can be changed, focusing on the height of the sun in this period. So, in winter, the angle of inclination should be maximum, and in summer, the panels should be at a lower angle.
- The collector panels should be installed as close as possible to the room to be heated in order to reduce heat loss. Effective installation of the collector on the southern slope of the roof of the house or on the gable. This minimizes heat loss, but additional holes will have to be made in the roof.
- On the place chosen for installation of a collector the shadow from fences, trees or other structures should not fall.
It should be borne in mind that in winter the shadows are much longer due to the low position of the sun above the horizon.
After choosing the optimal place, you need to decide on the materials that will serve as heat sinks. For homemade air collector suitable aluminum cans from under the drinks. Convenience is obvious - aluminum has a high thermal conductivity and is easy to cut, the banks are standard sizes and are joined one above the other.
After the required number of cans is collected, they must be thoroughly washed, dried, cut holes in the neck and bottom, glued with glue and sealant and painted black.
The number of cans in length and width should match the size of the panel. After placing the battery cans in the panel, you need to organize the supply and exhaust ducts. To do this, you can use ready-made tubes that are sold for the installation of ventilation. In the process of assembling the system, it is necessary to provide for the insulation of the rear side of the panel and the upper glass. It can be replaced with a piece of polycarbonate.
The finished collector can be connected to the room ventilation system or left autonomous. For greater efficiency, a fan is connected to it. The temperature difference at the inlet and outlet in such a collector can reach 35 degrees.
In addition to air, you can organize and water heating. As the heat sinks can serve as iron or aluminum batteries, pipe or hose PND. If the collector is planning
use year-round, the system should be double-circuit and pour antifreeze or any other coolant as a coolant.
The device in your home or in the country of a solar collector can significantly reduce heating costs and fully meet the needs for hot water.