In the last decade, solar energy as an alternative source of energy is used more and more for heating buildings and provide hot water. The main reason - the desire to replace the traditional fuel accessible, environmentally clean and renewable energy resources.
Converting solar energy into heat takes place in the Solar - module design and operating principle determines the specificity of its application.
In this article we look at the variety of solar collectors and principles of their operation, as well as tell you about popular models of solar modules.
The content of the article:
- The feasibility of using solar
- The general design and function
Variety of solar collectors
- Vacuum - for cold and temperate climate
- Water - the best option for the southern latitudes
Solar: features of the design and operation
- Active and passive range
- Thermosiphon and circulation systems
- Technical schemes solution, one - and two-circuit
- Working conditions and efficiency
- Popular model "solar" modules
- Conclusions and useful videos on the topic
The feasibility of using solar
Geliosistema - system for converting solar radiation into thermal energy, which is then passed to a heat exchanger for heating the coolant or heating water system.
Efficiency solar thermal installation depends on the insolation - the amount of energy supplied for a light day on the surface of 1 square meter at an angle of 90 ° relative to the direction of sunlight. Measuring the value of the index - kWh / sq m, the value varies depending on the season.
The average level of solar insolation for the temperate continental climate of the region - 1000-1200 kWh / square meter (per year). The amount of the sun - defining the parameter to calculate the solar performance.
Using an alternative energy source to heat the house allows getting hot water without traditional energy - solely by solar radiation
Installation gelioteplosnabzheniya system - an expensive event. To capital expenditures were justified, an accurate calculation of the system and compliance with the installation technology.
Example. The average value of insolation for Tula in midsummer - 4.67 kW / m * day provided installation panel at an angle of 50 °. Performance solar collector 5 square meters is calculated as follows: 4.67 * 4 = 18.68 kW of heat energy per day. This volume is sufficient for 500 liters of water heated to a temperature of from 17 ° C to 45 ° C.
As practice shows, using solar, the owners of the cottage in the summer can completely go with the electric or gas water heater on a sunny method
Speaking about the feasibility of the introduction of new technologies, it is important to take into account the specific technical features of the solar collector. Some start working at 80 W / m of solar energy and other enough - 20 W / sqm
Even in the southern climate, the use of the collector system only not pay for heating. If the installation will be used exclusively in the winter sun with a deficit, the cost of the equipment is covered and for 15-20 years.
To maximize geliokompleks, it must be included in the hot water system. Even in winter geliolektor would "cut" account for energy for heating water up to 40-50%.
According to experts, with domestic use of solar system pays for itself in about 5 years. With the growth in prices for electricity and gas, the payback period of the complex will be reduced
In addition to the economic benefits of "solar heating" has additional advantages:
- Environmentally friendly. Reduced carbon dioxide emissions. Over 1 year sq solar collector into the atmosphere prevents 350-730 kg mining.
- Aesthetics. Space of a compact bath or kitchen manages to get rid of bulky boilers or geysers.
- Durability. Manufacturers claim that, subject to installation technology, the complex will last about 25-30 years. Many companies provide a guarantee of up to 3 years.
Arguments against the use of solar energy: a pronounced seasonality, depending on weather and high initial investment.
The general design and function
Consider the embodiment with the solar collector as a primary system operating element. Exterior unit resembles a metal box, the front side of which is made of tempered glass. Inside the box is located a working body - the coil to the canister.
A heat absorbing block provides coolant heating - circulating fluid transfers heat generated in the water circuit.
Main components solar 1 - collector field, 2 - air vent, 3 - Distribution station 4 - tank pressure relief, 5 - Controller, 6 - tank heater, 7,8 - heating element and a heat exchanger 9 - termosmesitelny valve, 10 - flow rate of hot water, 11 - the delivery of cold water, 12 - drain, T1 / T2 - temperature sensors
Solar collector necessarily work in tandem with the storage tank. Since the coolant is heated to a temperature of 90-130 ° C, it can not be fed directly into the hot water taps or radiators. Heat transfer fluid enters the heat exchanger of the boiler. Storage tank is often supplemented by an electric heater.
Scheme of work:
- The sun heats the surface collector.
- Thermal radiation is transmitted absorbent member (absorber), which contains a working fluid.
- Circulating in the coil tubes is heated coolant.
- Pumps, control unit and provide the retraction control of the coolant conduit to the coil of the storage tank.
- Implemented heat transfer water in the boiler.
- The cooled coolant flows back into the reservoir and the cycle repeated.
The heated water from the heater is fed into the heating circuit or to the water intake points.
When constructing a heating system or year-round hot water, the system is equipped with an additional heating source (boiler, electric heater). This is a prerequisite for maintaining a predetermined temperature
Variety of solar collectors
Regardless of the destination, solar system comes with a flat or spherical tube geliokollektorom. Each option has a number of distinctive features in terms of performance and operation efficiency.
Vacuum - for cold and temperate climate
Solar collector vacuum structurally resembles a thermos - narrow tubes with coolant placed in flasks larger diameter. Formed between the vacuum vessels layer responsible for the thermal insulation (heat preservation - up to 95%). The tubular shape is optimal to hold the vacuum and "occupation" of the sun's rays.
The basic elements of a tubular solar thermal installation: the support frame, the heat exchanger body, vacuum glass tubes treated with highly selective coating for intensive "absorption" Solar energy
The inner (heat) tube filled with saline solution having a low boiling point (24-25 ° C). When heated liquid is evaporated - the evaporation flask move upward and heated heat medium circulating in the collector housing.
During the condensation of water droplets flow down in the tube tip and the process repeats.
Due to the vacuum within the liquid layer of the flask is capable of heat to boil and vaporize in subzero outdoor temperatures (up to -35 ° C).
Characteristics of solar modules depend on such criteria:
- tube design - fountain, coaxial;
- heat channel device - «Heat pipe», Co-current circulation.
Fountain bulb - a glass tube, in which the enclosed plate and the heat absorber duct. Vacuum layer extends across the channel length of the heat.
coaxial tube - double vacuum flask with "insert" between the walls of the two tanks. Heat transfer is carried out from the inner surface of the tube. Tip Heat-equipped vacuum indicator.
Efficacy fountain tubes (1) above as compared with coaxial models (2). However, the first is more expensive and harder to install. In addition, in case of breakage, feather flask have to change the whole
Channel «Heat pipe» - the most common heat transfer in solar collectors embodiment.
The mechanism of action is based on placement in sealed metal tubes of a volatile liquid.
The popularity of «Heat pipe» due to affordable price, unpretentious service and maintainability. Because of the complexity of the heat exchange process, the maximum level of efficiency - 65%
The continuous-flow channel - through a glass flask are parallel connected in a U-shaped metal arc tube
The coolant flowing through the channel is heated and supplied to the manifold housing.
Embodiments of structures of vacuum solar collector 1 - modification with «Heat pipe» central heating tube, 2 - a solar power plant with a co-current circulation of coolant
Coaxial and fountain tubes can be combined in different ways with the thermal channels.
Option 1. Coaxial with the bulb «Heat pipe» - the most popular solution. The collector occurs multiple heat transfer from the walls of the glass tube to the inner flask and then to the coolant. The degree of optical efficiency reaches 65%.
Driving device coaxial tube «Heat pipe»: 1 shell is made of glass, 2 - selective coating 3 - metallic fins 4 - vacuum 5 - Thermal flask legkozakipayuschim substance 6 - inner tube glass
Option 2. Coaxial flask with a co-current circulation is known as the, U-shaped collector. Due to the design reduces heat loss - the heat energy is transferred from the aluminum tubes with a circulating coolant.
Along with high efficiency (up to 75%) of the model has some drawbacks:
- installation complexity - bulb are integral with the body of a two-pipe manifold (mainfold) and are set entirely;
- It ruled out the replacement of single tubes.
In addition, U-shaped assembly demanding and expensive coolant «Heat pipe» models.
Device U-shaped solar collector 1 - glass "cylinder", 2 - absorbing coating 3 - Aluminum "Case", 4 - flask with coolant 5 - vacuum 6 - the inner tube is made of glass
Option 3. Pen tube with the principle of action «Heat pipe». Distinctive features of the reservoir:
- high optical characteristics - an efficiency of about 77%;
- flat absorber directly transfers energy to heat with the coolant tube;
- by utilizing a single glass layer is reduced reflection of solar radiation;
Possible replacement of the damaged element without emptying the solar system.
Option 4. Fountain bulb ram action - the most effective tool for the use of solar energy as an alternative energy source for heating water or home heating. High collector operates with efficiency - 80%. The disadvantage of the system - the difficulty of repair.
Scheme fountain device solar collector 1 - solar system with «Heat pipe» channel, 2 - geliokolektora twin-tube housing with coolant movement propulsive
Regardless of the performance tube collectors have the following advantages:
- operability at a low temperature;
- low heat loss;
- the duration of operation during the day;
- ability to heat the coolant to a high temperature;
- low windage;
- ease of installation.
The main drawback of the vacuum models - the impossibility of self-cleaning of the snow cover. Vacuum layer does not transmit the heat to the outside, so the layer of snow melts and covers the sun access to the collector field. Additional disadvantages: the high cost and the need for working angle flasks not less than 20 °.
More details about the working principle of vacuum solar collector tubes to read Further.
Water - the best option for the southern latitudes
Flat (panel) Solar collector - a rectangular aluminum plate, a closed top plastic or glass cover. Inside the box is arranged an absorption field, the metal coil and insulation layer. collector area is filled with a flow conduit through which coolant moves.
The basic components of a flat solar collector: a housing, an absorber, a protective coating, a layer of insulation, and fasteners. When assembling the frosted glass is used with an indicator transmission spectral range 0.4-1.8 microns
Heat absorption by a highly selective absorbent coating reaches 90%. The flow conduit is arranged between the metallic "absorbent" and thermal insulation. It is used two tubes laying schemes: "Harp" and "meander".
Tubular collector with heat transfer fluid acts as a "greenhouse" effect - the sun's rays penetrate through the glass and heated tubing. Due tightness and heat insulation is maintained within the panel.
The strength of the solar module is largely determined by the material of the protective cover:
- ordinary glass - the cheapest and brittle coating;
- strained glass - a high degree of light scattering and increased strength;
- antirefleksnoe glass - different maximum absorption capacity (95%) by the presence of the layer depleting reflected rays of the sun;
- self-cleaning (polar) glass with titanium dioxide - organic pollution fade in the sun, and the remains of garbage washed away by rain.
Most endures blows polycarbonate glass. The material is installed in expensive models.
Reflection sunlight absorbing ability: 1 - antirefleksnoe coating 2 - tempered safety glass. The optimum thickness of the protective outer sheath - 4 mm
Operational and functional features panel solar power plants:
- in forced circulation systems is provided defrosting function allows you to quickly get rid of the snow cover at Heliopolis;
- prismatic glass captures a wide range of beams from different angles - efficiency of the plant in the summer reaches 78-80%;
- the collector is not afraid of overheating - if an excess of thermal energy possibly forced cooling the coolant;
- improved impact strength as compared with tubular counterparts;
- can be mounted at any angle;
- affordable pricing.
Systems are not without drawbacks. Between the solar radiation deficiency with increasing temperature difference, the efficiency of a flat solar collector falls significantly due to insufficient thermal insulation. Therefore, the panel module pays off in the summer or in warm climates.
Solar: features of the design and operation
The variety of solar systems can be classified according to parameters: the method of use of solar radiation, the method of circulation of the coolant, and the number of circuits operating seasonality.
Active and passive range
In any solar energy conversion system has a suntrap. Proceeding from a method of using generated heat geliokompleksov two types: passive and active.
The first kind - solar heating system where the heat sink element sunlight act structural elements of the building. As geliopriemnoy surface act roof, wall or window-collector.
Scheme passive low-temperature solar collector with a wall-: 1 - sun, 2 - a translucent screen 3 - air barrier 4 - heated air, exhaust air flows 5-, 6 - thermal radiation from the wall, 7 - the heat absorbing surface of the collector wall, 8 - decorative shutters
In European countries, passive technologies are used in the construction of energy efficient buildings. Geliopriemnye surface decorated with a false window. For the coated glass is placed brick wall with svetoproemami blackened.
As the storage tank are the elements of construction - walls and ceilings, polystyrene insulated from the outside.
Active systems involve the use of stand-alone devices that are not related to construction.
In this category are discussed above complexes with tubular, flat plate collectors - solar thermal installation is usually placed on the roof of the building
Thermosiphon and circulation systems
Solar thermal equipment with the natural movement of the coolant circuit of the collector-accumulator-collector carried by convection - warm fluid with low density rises cooled - flows way down.
In systems of thermosiphon storage tank is located above the reservoir, providing a spontaneous circulation of the coolant.
Scheme of characteristic seasonal single loop systems. Thermosiphon complex is not recommended for the collectors, an area more than 12 m
Gravity solar system is a wide range of shortcomings:
- on cloudy days of the complex performance falls - for coolant flow large temperature difference is required;
- heat loss due to a slow movement of the liquid;
- risk of overheating due to uncontrollability tank heating process;
- instability of the collector;
- the complexity of the placement of the storage tank - for installation on the roof of the heat loss increases, accelerated corrosion processes, the risk of freezing pipes appears.
Pros "gravity" of the system: simplicity of design and affordability.
Capital costs for the circulation arrangement (forced) considerably higher solar installation unconfined complex. The circuit "cuts" pump for coolant flow. Job controller operated pump station.
Additional thermal power generated by forcibly complex power exceeds consumed by pumping equipment. effectiveness of the system will increase by a third
Such a process is involved in circulation year-round dual-circuit solar heating units.
A full-featured set of pros:
- unlimited choice of the location of the storage tank;
- performance out of season;
- selection of the optimum heating mode;
- Safety - lock operation in case of overheating.
The disadvantage of the system - dependent on electricity.
Technical schemes solution, one - and two-circuit
In single-loop installations circulating fluid that subsequently is supplied to the water intake points. In winter, the water drained from the system is necessary to prevent freezing and cracking tubes.
Features single-circuit solar heating systems:
- Recommended "refill" system nonrigid purified water - deposition of salts on the tube walls leads to clogging of channels and reservoir damage;
- corrosion due to the excess air in water;
- limited lifetime - within four to five years;
- high efficiency in the summer.
The combi geliokompleksah special circulates coolant (antifreeze with antifoam and anti-corrosion additives), water gives off heat through the heat exchanger.
single-circuit device (1) and dual-circuit (2) Solar. The second option is more reliable, the ability to work in the winter and operation duration (20-50 years)
Nuances of operation of a bypass module: a slight decrease in efficiency (3-5% less than in the single-system), the need for complete replacement of the coolant every 7 years.
Working conditions and efficiency
Calculation and installation of solar systems is best left to professionals. Compliance with the installation equipment to ensure the efficiency and performance of applications received. To improve the efficiency and the period of service must take into account some of the nuances.
Thermostatic valve. In traditional heating systems thermostatic element rarely installed as for temperature control responds heat source. However, the regeneration of the solar safety valve must not be forgotten.
Heating the tank to the maximum allowable temperature of the collector increases performance and allows to use solar heat even in cloudy weather
Optimal placement of the valve - 60 cm from the heater. In close proximity "thermostat" is heated and blocks the flow of hot water.
Placement of the storage tank. DHW buffer tank must be installed in an accessible location. When placed in a compact room focuses on the height of ceilings.
The minimum free space above the tank - 60 cm. This clearance is required for maintenance and the battery replacement magnesium anode
installation expansion tank. Member compensates thermal expansion in the stagnation period. Installation of the tank above the pump equipment will provoke overheating of the membrane and its premature wear.
The optimal place for the expansion tank - under pumping group. Temperature effect in this installation is significantly reduced, and the membrane is longer retains elasticity
Connecting the solar circuit. When connecting the pipes is recommended to arrange the loop. "Termopetlya" reduces heat loss by preventing the heated fluid outlet.
Technically correct way to "loop" the solar circuit. Neglecting requirement causes a temperature decrease in the storage tank at 1-2 ° C over night
The check valve. Warns "overturning" circulation of the coolant. With a lack of solar activity check valve does not dissipate heat accumulated during the day.
Popular model "solar" modules
Demand for solar domestic and foreign companies. Good reputation won the product manufacturers: NPO Machine Building (Russia), Helion (Russia), Ariston (Italy), Viola (Ukraine), Viessman (Germany), the Amcor (Israel) and others.
"Falcon" solar system. Flat Solar collector, equipped with an optical multilayer coated with magnetron sputtering. The minimum emission capacity and high absorption rate provide efficiency up to 80%.
- Working temperature - up to -21 ° C;
- reverse heat radiation - 3-5%;
- the top layer - glass (4 mm).
Collector CRS-A (Viola). Vacuum solar thermal system with absorption area 0,8-2,41 m (depending on model). Coolant - propylene insulated copper heat exchanger 75 mm minimizes heat loss.
- housing - anodised aluminum;
- coil diameter - 38 mm;
- isolation - with rockwool antigigroskopichnoy treatment;
- coating - borosilicate glass of 3.3 mm;
- Efficiency - 98%.
Vitosol 100-F - Solar collector flat horizontal or vertical assembly. Copper absorber arfoobraznym tubular coil and titanium coated. Light transmission - 81%.
The tentative prices Solar: Flat solar collectors - from 400 USD / sq.m, tubular solar collectors - 350 USD / 10 vacuum flasks. A complete set of the circulation system - from 2500 USD
Conclusions and useful videos on the topic
Principle of operation of solar collectors and their types:
Assessment of the Performance of a flat collector-zero temperatures:
Technology mounting panel solar collector on the example of Buderus models:
Solar energy - renewable sources provide heat. Taking into account the rise in prices for traditional energy resources justifies the introduction of solar systems, and capital investment pays off in the next five years, subject to installation technology.
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