About how much free heat we can give summer the streams of sunlight that often comes to mind in summer, with violent heat and burning in the sun asphalt and walls. In clear summer weather, per square meter may fall from 600 to 800W/h Is a lot. If you multiply the square of sunlit farmsteads or roof, using solar collector to collect energy, comparable in magnitude with the needs of heating the home.
Solar thermal collectors allow you to collect energy and to direct the received heat in the right direction:
- Providing hot water for the shower, bathroom and kitchen;
- Heating a small enclosed greenhouses or garden of any design almost all year round;
- A significant additive in the heating circuit of the house in the cold and almost full support in the cool autumn days.
The collector is designed to collect solar energy in its most useful form. Conditionally on the device of their solar collector design can be divided into three main groups:
- Vacuum multi-tube or flat with forced or natural circulation of coolant. Most often this stationary design, designed for seasonal work.
- Air solar collectors, the most simple and easy. The accumulated heat is removed from the heated surface of the collector air flow.
- In the third embodiment of the solar collectors and the resulting heat can be used to convert this into electricity, ranging from thermohardening installations, to complex machines pyroelectricity devices.
The last group of products rarely finds a demand among the population due to the high cost and complexity of service.
The simplest variation of the flat design of the solar collector is panoramiczny variant with two-layer heat sink. The device itself according to the principle of operation is similar to the country version of summer shower, which is based on a barrel treated by the outer surface of the bitumen mastic or black paint.
To increase the amount of collected solar energy design of a solar collector is performed in a flat container of relatively small thickness, 5-7cm, width and length of the device depends on the specific needs of the power collector. One of the walls is made of anodized aluminum and painted in black as soot, color, no Shine. This so-called reception, or the working surface of the collector. On the inner side of the working part of the collector often are a thin rib of aluminum or plastic to improve heat removal of energy from the wall of the working surface to the coolant – water or antifreeze.
To reduce contamination and losses on the work surface are mounted a thin transparent film or sheet of plastic or glass, having good insulating characteristics. On the inner side, such protection is deposited mirror layer of aluminum, which allows to reduce heat loss by reflection and convection.
Design of flat solar collector can have instead of the usual aluminium sheet wall sandwich of powder of graphite, metal fibers and the reinforcing resin. Such a material with good thermal conductivity and high oxidation resistance.
Such structures are mandatory and are mounted on reinforced frame, usually on the Sunny side of the roof or the wall of the house.
For all its simplicity, reliability and low cost flat solar drives offer relatively good efficiency of heat only on a Sunny day. For higher latitudes in the early spring – late autumn heat output it crashes half.
Higher efficiency in comparison with flat solar collectors have a vacuum system. The design of inherent individual thermal element vacuum tube, the principle of operation of such a solar collector based on known physical device is a heat pipe, is quite complex and capricious, but efficient. Design features an ultra-high conductivity, thanks to which all the heat trapped on one end of the tube, in a matter of moments to assemble and is concentrated at the opposite end.
The vacuum element is an elongated flask-up of durable glass, inside of which is sprayed the mirror coating. Thanks to the one-way mirror, solar energy flow freely into the inside of the bulb and can not escape back effectively absorbed copper by the end of the heat tube placed inside the housing of the bulb. To reduce losses to the air from a glass flask is pumped out. Obtained from the luminous flux energy to the Central copper element passes the flow of coolant, typically antifreeze, or directly in the water tank.
Advantages of solar energy conversion in the embodiment with heat pipe:
- The efficiency of absorption and conversion of solar heat is 3-4 times higher and the air flat collector;
- Works well in the temperature range 0-50onWhereas other types of solar collectors, according to user reviews, have a working range from 20onWith;
- Less sensitive to the direction and the angle of incidence of sunlight. For normal operation of the solar collector is enough to be lit by the sun even at an acute angle of incidence of sunlight, the rest constructions of solar collectors at the output for optimum lighting angle of more than 20on the efficiency drops 10% per hour.
- Light weight design of the solar storage allows you to install it directly on the roof, without pillars.
When planning an acquisition is to make an indicative calculation of the area of the solar collector, based on the ratio: square meter will give a day of about 50-55литров hot water, but not boiling water. More accurate information can be found on the websites of the companies involved in the production of solar collectors. There you can obtain information on the cost of products. Each firm demonstrates overharvesting and cheapness of its products. A vacuum of 15 items will cost about 15-20 thousand. rubles for the heating power 1.3-1.5 kW and the storage tank 80-100литров.
Interesting features of such systems of solar collectors include the possibility of the health check every vacuum flask on their own, without any special tools. Enough in the evening, in an idle state, put his hand to the lower end of the tube. If the item is a long time to stay cold, and the sealing of the bulb is not a frost-like patina, this device is OK.
Hot water from the tank can be fed by gravity, but often set to low power primer pump to quickly fill the tank after using up hot water. In more serious design solar collector combined with a heat accumulator and an electronic control system and control hot water and heating. The cost of these systems is not less than 1000EUR. The warranty on the system with the heat pipes, as a rule, makes from 5 to 25 years, depending on the level of quality of the materials used in the device.
The more complex the design, the more expensive it is to operate, and more probability of unexpected failure. In this issue of the collector design with the air heat transfer are Champions in simplicity and reliability. In fact, the air manifold is a set of vertical channels or tubes with a matte black coating. In the work of manifold uses the principle of acceleration of heated air in a vertical tube.
The benefits and advantages of the aircraft design should include:
- Highest reliability and simple construction;
- The small weight of the device, the flexibility and ease of installation;
- Minimum power consumption on the fan, sometimes the fan can be switched off and heated by gravity.
Construction of the collector consists of a large number of thin-walled aluminum tubing with a blackened matte finish. Battery tubes has a Central inlet and cold outlet hot air ducts, cold set the centrifugal fan of zero resistance. If necessary it can be disabled and in this condition practically does not create resistance to a moving air stream.
The device has the air intake to regulate the amount and ratio of air take from the outside, from the heated space.
In the heating efficiency of air collectors is almost flat systems, require a vertical placement of the pipes and of maximum illumination by the sun. Power easily adjusted by selecting the number of tubes of the heat exchanger. It often happens that the air solar collectors are indispensable in the heating and ventilation of various warehouses, are used for drying of various vegetable and fruit products.