Classification of solar collectors
⦁ The classification is based on the way they collect solar radiation. The non-concentrating type absorbs the radiation as it is received on the surface of the collector while the concentrating type first increases the concentration of radiation per unit area before absorbing it.
⦁ Further, based on the technique employed for concentration of radiation, the concentrating type is further categorized into focus and non-focus types. The focus type is further subdivided into line and point focus depending on the focusing method.
⦁ While non-focus type collectors consume both beam and diffuse radiation, the focus type collectors make use of beam radiation only, as diffuse radiation cannot be concentrated.
⦁ The important features of a solar collector are:
⦁ Collector efficiency: It is defined as the ratio of the energy actually absorbed by the collector to the energy incident on the collector.
⦁ Concentration ratio (CR): It is the ratio of the area of the aperture of the system to the area of the receiver. The aperture of the system is the projected area of the collector facing the beam.
⦁ Temperature range: It is the range of temperature to which the heat transport fluid is heated by the collector.
⦁ Non-concentrating collector or flat plate collector
⦁ In it, the area of a collector to catch the solar radiation is equal to the absorber plate. Here no optical system is used to reduce the solar radiation and therefore the concentration ratio is just 1.
⦁ Flat plate collector is the most substantial component of any solar thermal energy system. It is basically a heat exchanger which transfers the radiant energy of the incident sunlight to the sensible heat of a working fluid-liquid or air.
⦁ Flat plate collectors are designed for operation in the low temperature range, from ambient to 60˚C, or the medium temperature range, from ambient to 100˚C.
⦁ The constructional details of a simple flat plate collector are shown in Fig. 1.2.
Construction of flat plate collector
Basic elements of a flat plate collector:
⦁ Transparent cover (one or two sheets) of glass or radiation transmitting plastic film.
⦁ Blackened absorber plate usually of copper, aluminium or steel, typically 1-2mm thick.
⦁ Tubes (typically 1-2 cm DIA.), passages or channels, in thermal contact with the absorber plate or connected to it.
⦁ Thermal insulation usually of fiberglass or expended polystyrene, typically 5-10cm in thickness is provided at the back and sides to minimize the heat losses.
⦁ Tight container or casing to insert the above ingredients.
Working of flat plate collector:
⦁ As solar radiation impinges on specially treated metallic absorber plate, it is absorbed and increases its temperature.
Solar energy is energy taken from the light that reaches earth's surface from the sun. There are four different kinds of solar energy, which are active solar systems, passive solar systems, photovoltaic cells and concentrating power systems. An active solar systems is a system that captures solar energy by mechanical means. Common active solar systems are often in buildings or homes. Some examples are roof collectors and water heating. Low Intensity and high variability have limited the use of active solar energy in Canada. A pass...
The Solyndra Company, founded in 2005 by Christian Gronet, designed, manufactured, and sold a unique type of solar panels. They were termed “solar photovoltaic (PV) systems” and were designed for large, flat to low sloped commercial building roofs. The panels were designed to have the best performance when mounted horizontally and to be installed very close together so that they covered a much higher percentage of the roof top thus producing more electricity than the typical flat panel solar panels by comparison. This was created through the production by absorbing light from all directions including indirect and reflected light as well as direct sunlight when combined with a white roof. This was due to the design of having rolled its copper indium gallium selenite or CIGS into a cylindrical shape. Each tube had 40 of them in each 1-meter-by-2-meter panel (Solyndra, 2008).
good emitter of heat radiation so a lot of heat will be lost to the
Three types of heat transfers help solar cookers use the sun’s energy to cook food. Heat is always transferred from the warmer object to the cooler object. Heat is also transferred to and through some materials better than others. The three types of heat transfers are radiation, conduction, and convection. Convection is the heat transfer by movement through materials such as air or a liquid. Materials like these are called mediums. Convection is the primary way heat can be transferred through liquids and gases. To classify a heat transfer as convection, hot air has to rise up to equally heat the air around it. Box solar cookers have to retain this hot air to cook food, so the cookers have to have lids with a transparent covering. The transparent covering shuts in all of the hot air and keeps out the cool air. The second heat transfer is the transfer of heat between two objects, or substances, that are directly in contact with each other. This heat transfer, called conduction is the primary way heat can be transferred through solids. In gases and liquids, conduction works poorly because the atoms have a great deal of space between them. Since they have a lot of space between each other, they can’t communicate heat to one another. The solid, aluminum foil, is commonly used in homemade solar ovens because it is a metal. It is well known metal is a great conductor of heat. Since metal (aluminum) is a great conductor of heat, whatever comes in contact with it will gradually absorb the heat from the metal. The third type of heat transfer is radiation. Radiation is the transfer of energy (heat) through space by electromagnetic waves. Solar energy reaches Earth by radiation (Pearson 485). When an energy wave comes directly in contact with...
2) Mirror image rule - The absorption spectrum is a mirror image of the emission spectrum for many fluorophores. This is known as the mirror image rule.
The effectiveness of PV module depends on how perpendicular the sunrays fall on the PV. If PV is facing toward the sun, it produces maximum power. Stationary solar panels cannot face toward the sun all day as sun moves. However, maximum radiation depends on two other aspects of stationary solar panels. One is the direction and the other is the tilt angle of the panels. A meter long panels can generate maximum of 1000W, if sunlight strikes directly on it. Few factors affect the sunlight strikes a PV panel. When the sunlight passes through the air, air molecules such as dust, vapor, clouds, volcanoes can absorb some of the radiation. This absorbed part of radiation is known as diffuse solar radiation. Atmospheric conditions have great effect on solar radiation. The solar radiation can decrease 10% to 100% depending on
absorb the energy from the sun, but it does absorb some of the heat energy
Rotman, David. "Finding a Solar Solution." Technology Review 2 (2012): 48-51. Print. 22 November 2014.
Passive solar design and architecture may seem like a distant dream in our fast paced modern world, but in reality it’s more of a modern revival of a style of energy efficient building that has been around for millennia. What once seemed to be common sense ideas for designing a house that could both keep you cool in the summer and warm in the winter has somehow been forgotten since we started to overuse the planet’s resources on our own comforts. When heating a house took lots of effort it was the wise choice to design a building that could use the energy provided by the sun in the most advantageous ways. Unfortunately, in my opinion, since all we have to do now to heat our house is a turn a dial and pay the bills, many of the simplest ways to cut down on our rising energy consumption have been completely disregarded. Fossil fuels allowed people to provide artificial light and temperatures. This meant that houses could be built without paying attention to the natural world. However, as more and more people agree that fossil fuels will almost certainly run out sometime in the next century, there has been a growing revival in passive solar design. Here, I hope to show you some of the basic principles of passive solar design and how they helped people thousands of years ago in an effort to make people understand how these ancient techniques can be improved on today to help with our growing energy problem.
Siegel, RP. "Solar Thermal: Pros and Cons - Part 1: Solar Heating and Cooling." Triple Pundit RSS. N.p., 21 May 2012. Web. 04 Mar. 2014. .
The first telescope developed, and the one most widely used, is the optical telescope, which gathers visible light radiation. There are three basic types of optical telescopes: refractors that use lenses, reflectors that use mirrors, and catadioptrics that use a combination of both lenses and mirrors.
Light can be classified as a form of electromagnetic radiation, which includes visible light. The ‘light’ commonly referred to in everyday life belongs in this category. The electromagnetic spectrum includes other types of radiation such as gamma rays, radio waves and cosmic rays, all of which possess distinct wavelengths, frequencies and energy levels. These forms of electromagnetic radiation are not visible to the human eye but can be perceived by selected species of animals, such as bees. Figure 1 below displays the electromagnetic spectrum and provides a basic insight into the respective characteristics of different forms of radiation.
Solar power utilizes the sun’s energy to produce electricity, unlike other sources of energy, which rely on continual mining for raw materials. Consequently, producing solar energy from the heat from the sun does not result in the annihilation of the ecosystem, compared to the extraction of fossil fuels (Bode, 2005). Therefore, with the use of solar energy, it will help keep the environment clean, thus helping to combat the issue of global warming, which is a threat to the world’s ecosystem worldwide. The use of solar energy will help save the worlds vegetation, and help prevent the effects of global warming in future.... ... middle of paper ...
Hot Water Heaters: The easiest way to exploit solar radiation is as thermal energy. One way to harness this solar energy is to heat water. Aro...
Generally one of the most well known kind of solar systems, photovoltaics are found across multiple common solar applications. Photovoltaics make up solar panels across nations and can stand alone in a glass casing to act as a solar charger for cars and batteries (Hezel 2003, p 554). They can be attached to rooftops or stand together in solar farms, acting as a solar power grid.