 Solar Thermal Collector Dish A solar thermal collector is a solar collector specifically intended to collect heat: that is, to absorb sunlight to provide heat. Although the term may be applied to simple solar hot water panels, it is usually used to denote more complex installations. There are various types of thermal collectors, such as solar parabolic, solar trough and solar towers. These type of collectors are generally used in solar power plants where solar heat is used to generate electricity by heating water to produce steam and driving a turbine connected to the electrical generator. Image File history File links No higher resolution available. ...
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Image File history File links Portal. ...
A laundromat in California with solar collectors on the roof. ...
For other uses, see Heat (disambiguation) In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature. ...
Absorption, in optics, is the process by which the energy of a photon is taken up by another entity, for example, by an atom whose valence electrons make a transition between two electronic energy levels. ...
Prism splitting light High Resolution Solar Spectrum Sunlight in the broad sense is the total spectrum of the electromagnetic radiation given off by the Sun. ...
A solar heater A laundromat in California with solar hot water panels on the roof. ...
Solar thermal energy is a technology for harnessing solar power for practical applications from solar heating to electrical power generation. ...
Lightning strikes during a night-time thunderstorm. ...
A Siemens steam turbine with the case opened. ...
“Dynamo†redirects here. ...
Types
Flat plate and box-type collectors are typically used in domestic and light industry applications. Parabolic troughs, dishes and towers are used almost exclusively in solar power generating stations or for research purposes. Solar thermal energy is a technology for harnessing solar power for practical applications from solar heating to electrical power generation. ...
Flat plate
 Solar thermal system for water heating - these are deployed on flat roof. This is the most common type of solar thermal collector, and is usually used as a solar hot water panel to generate solar hot water. A weatherproofed, insulated box containing a black metal absorber sheet with built in pipes is placed in the path of sunlight. Solar energy heats up water in the pipes causing it to circulate through the system by natural convection. The water is usually passed to a storage tank located above the collector. This passive solar water heating system is generally used in hotels and homes in sunny climates such as those found in southern Europe. Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (1280 × 960 pixel, file size: 546 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ...
Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (1280 × 960 pixel, file size: 546 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ...
Solar hot water refers to water heated by solar energy. ...
For these purposes, the general practice is to use flat-plate solar energy or evacuated tube collectors with a fixed orientation (position). The highest efficiency with a fixed flat-plate collector or evacuated tube collector is obtained if it faces toward the sun and slopes at an angle to the horizon equal to the latitude plus about 10 degrees. Solar collectors fall into two general categories: nonconcentrating and concentrating. Solar power describes a number of methods of harnessing energy from the light of the sun. ...
Collector - in electronics, the amplified terminal on a Bipolar junction transistor (PNP) or (NPN) list of collectors- People with note-worthy collections. ...
Sol redirects here. ...
In the nonconcentrating type, the collector area (i.e. the area that intercepts the solar radiation) is the same as the absorber area (i.e., the area absorbing the radiation).
There are many flat-plate collector designs but generally all consist of (1) a flat-plate absorber, which intercepts and absorbs the solar energy, (2) a transparent cover(s) that allows solar energy to pass through but reduces heat loss from the absorber, (3) a heat-transport fluid (air or water) flowing through tubes to remove heat from the absorber, and (4) a heat insulating backing. One flat plate collector is designed to be evacuated, to prevent heat loss.
The most effective use of collectors is with a sealed heat exchange system, rather than having the potable water flow through the collectors. A mixture of water and propylene glycol (which is used in the food industry) can be used as a heat exchange fluid to protect against freeze damage, up to a temperature that depends on the proportion of propylene glycol in the mixture.
The first accurate model of flat plate solar collectors were developed by Hottel and Whillier in the 1950's.
Evacuated Tube
Evacuated (or vacuum) tubes panel. These collectors have multiple evacuated glass tubes which heat up solar absorbers and, ultimately, solar working fluid (water or an antifreeze mix -- typically propylene glycol) in order to heat domestic hot water, or for hydronic space heating. The evacuated tubes minimize the re-radiation of infrared energy from the collectors, allowing them to reach considerably higher temperatures than most flat-plate collectors. For this reason they can perform well in colder conditions. The advantage is largely lost in warmer climates, except in those cases where very hot water is desirable, for example commercial process water. The high temperatures that can occur may require special system design to avoid or mitigate overheating conditions. A further advantage this design has over the flat-plate type is that the constant profile of the round tube means that the collector is always perpendicular to the sun's rays and therefore the energy absorbed is approximately constant over the course of a day. Image File history File links U.S. Department of Energy File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Image File history File links U.S. Department of Energy File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Look up Vacuum in Wiktionary, the free dictionary. ...
Antifreeze is used in internal combustion engines, and for many other heat transfer applications, such as electronics cooling and chillers for HVAC. Compounds are added to water to reduce the freezing point of the mixture to below the lowest temperature that the system is likely to be exposed to, and...
Propylene glycol, also known as 1,2-propanediol, is an organic compound (a diol alcohol), usually a tasteless, odorless, and colorless clear oily liquid that is hygroscopic and miscible with water, acetone, and chloroform. ...
Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ...
Pool or Unglazed This type of collector is much like a flat-plate collector, except that it has no glazing/transparent cover. It is used extensively for pool heating, as it works quite well when the desired output temperature is near the ambient temperature (that is, when it's warm outside). As the ambient temperature gets cooler, these collectors become extremely ineffective.
Air These collectors heat air directly, almost always for space heating. They are also used for pre-heating make-up air in commercial and industrial HVAC systems HVAC systems use ventilation air ducts installed throughout a building that supply conditioned air to a room through rectangular or round outlet vents, called diffusers; and ducts that remove air from return-air grilles Fire-resistance rated mechanical shaft with HVAC sheet metal ducting and copper piping, as well as...
Box type A common solar cooker is a box type collector. It is a metal box open from top, and insulated from sides with an equally sized mirror hinged to it (like a simple box with a mirror attached to the underside of the cover). A solar box cooker is an insulated transparent-topped box with a reflective lid. ...
Parabolic trough This type of collector is generally used in solar power plants. A trough-shaped parabolic reflector is used to concentrate sunlight on an insulated tube (Dewar tube) or heat pipe, placed at the focal point, containing coolant which transfers heat from the collectors to the boilers in the power station. Image File history File links Smallsketch. ...
Image File history File links Smallsketch. ...
Solar thermal energy is a technology for harnessing solar power for practical applications from solar heating to electrical power generation. ...
A parabolic reflector (also known as a parabolic dish or a parabolic mirror) is a reflective device formed in the shape of a paraboloid of revolution. ...
Dewar tubes are constructed like Dewar flasks, but unsilvered and open at both ends, to allow a heat transfer fluid to flow through and absorb sunlight. ...
A heat sink (aluminium) with heat pipe (copper) A heat pipe is a heat transfer mechanism that can transport large quantities of heat with a very small difference in temperature between the hot and cold interfaces. ...
Child – 5:16 All I Need – 3:55 Drifting – 6:43 Hold On – 4:40 Open Me – 3:35 Beautiful – 5:44 Look In – 4:14 Without You – 4:55 Live It – 7:23 Dont Walk Away – 3:04 Lead Me On – 5:34 Rest – 5:06 Child [Piano...
A coolant, or heat transfer fluid, is a fluid which flows through a device in order to prevent its overheating, transferring the heat produced by the device to other devices that utilize or dissipate it. ...
A boiler is a closed vessel in which water or other fluid is heated under pressure. ...
Parabolic dish It is the most powerful type of collector which concentrates sunlight at a single, focal point, via one or more parabolic dishes -- arranged in a similar fashion to a reflecting telescope focuses starlight, or a dish antenna focuses radio waves. This geometry may be used in solar furnaces and solar power plants. Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (1024 × 768 pixel, file size: 52 KB, MIME type: image/jpeg) I have created this image. ...
Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (1024 × 768 pixel, file size: 52 KB, MIME type: image/jpeg) I have created this image. ...
A parabola A graph showing the reflective property, the directrix (light blue), and the lines connecting the focus and directrix to the parabola (blue) In mathematics, the parabola (from the Greek: παÏαβολή) (IPA pronunciation: ) is a conic section generated by the intersection of a right circular conical surface and a plane...
A reflecting telescope (reflector) is an optical telescope which uses a combination of curved and plane (flat) mirrors to reflect light and form an image (catoptric), rather than lenses to refract or bend light to form an image (dioptric). ...
A dish antenna is a type of antenna in which a parabolic dish focuses a signal onto an antenna, located at the parabolas focal point. ...
solar oven A solar oven or solar furnace is a way of harnessing the suns power to cook food. ...
Solar thermal energy is a technology for harnessing solar power for practical applications from solar heating to electrical power generation. ...
There are two key phenomenena to understand in order to comprehend the design of a parabolic dish. One is that the shape of a parabola is defined such that incoming rays which are parallel to the dish's axis will be reflected toward the focus, no matter where on the dish they arrive. The second key is that the light rays from the sun arriving at the earth's surface are almost completely parallel. So if dish can be aligned with its axis pointing at the sun, the incoming radiation will almost all be reflected towards the focal point of the dish -- most losses are due to imperfections in the parabolic shape and imperfect reflection.
Losses due to atmosphere between the dish and its focal point are minimal, as the dish is generally designed specifically to be small enough that this factor is insignificant on a clear, sunny day. Compare this though with some other designs, and you will see that this could be an important factor, and if the local weather is hazy, or foggy, it may reduce the efficiency of a parabolic dish significantly.
In some power plant designs, a stirling engine coupled to a dynamo, is placed at the focus of the dish, which absorbs the heat of the incident solar radiation, and converts it into electricity. See Knowing Parabolic Concentrators and Concentrating Solar power overview Cut away diagram of a Rhombic Drive Beta Stirling Engine Design Pink - Hot cylinder wall, Dark grey - Cold cylinder wall (with coolant inlet and outlet pipes in Yellow), Dark Green - Thermal insulation separating the two cylinder ends, Light Green - Displacer piston, Dark Blue - Power piston, Light Blue - Flywheels, Not Shown...
Power tower A power tower is a large tower surrounded by small rotating (tracking) mirrors called heliostats. These mirrors align themselves and focus sunlight on the receiver at the top of tower, collected heat is transferred to a power station below. Image File history File links No higher resolution available. ...
Image File history File links No higher resolution available. ...
A Heliostat is a device that tracks the movement of the sun. ...
Advantages - Very high temperatures reached. High temperatures are suitable for electricity generation using conventional methods like steam turbine or some direct high temperature chemical reaction.
- Good efficiency. By concentrating sunlight current systems can get better efficiency than simple solar cells.
- A larger area can be covered by using relatively inexpensive mirrors rather than using expensive solar cells.
- Concentrated light can be redirected to a suitable location via optical fiber cable. For example illuminating buildings, like here (Hybrid Solar Lighting).
A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ...
A solar cell, made from a monocrystalline silicon wafer A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. ...
Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length by confining as much light as possible in a propagating form. ...
Disadvantages - Concentrating systems require dual axis sun tracking to maintain Sunlight focus at the collector.
- Inability to provide power in diffused light conditions. Solar Cells are able to provide some output even if the sky becomes little bit cloudy, but power output from concentrating systems drop drastically in cloudy conditions as diffused light cannot be concentrated passively.
A backyard installation of passive single–axis trackers, DC rated at 2340 watts. ...
Diagram of diffuse reflection Diffuse reflection is the reflection of light from an uneven or granular surface such that an incident ray is seemingly reflected at a number of angles. ...
See also Insulated Glazing Unit or Insulating Glass Unit (commonly referred to as IGU) is described as two or more lites of glass spaced apart and hermetically sealed to form a single glazed unit with an air space between each lite. ...
In solar thermal collectors, a selective surface is chosen based on the ratio of radiation-absorption (alpha) to radiation-emission (epsilon), with a higher ratio meaning better performance. ...
A laundromat in California with solar collectors on the roof. ...
a solar oven A solar oven or solar cooker is a way of harnessing the suns power to cook food. ...
Passive solar design using an unvented trombe wall and summer shading A Trombe wall is a sun-facing wall built from material that can act as a thermal mass (such as stone, concrete, adobe or water tanks), combined with an air space, insulated glazing and vents to form a large...
Zeolite The micro-porous molecular structure of a zeolite, ZSM-5 Zeolites (Greek, zein, to boil; lithos, a stone) are minerals that have a micro-porous structure. ...
References - The US ratings of solar thermal collectors, updated regularly -- flat plate, evacuated, air and pool collectors rated
- Sorption Materials for Application in Solar Heat Energy Storage
- Solar Energy Blog Discuss new and out-of-the-box ideas on Solar energy and see how our future depends upon Solar Thermal power.
- Hottel, H. C. and Whillier, A.: "Evaluation of Flat-Plate Solar Collector Performance," Trans. of the Conference on the Use of Solar Energy - The Scientific Basis, Vol. 2, Tucson, AZ, Oct. 31- Nov. 1, 1955, pp 74-104.
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