1. 1. Applications of Different Energy sources
2. 2. Flat-plate collectors Flat-plate collectors are in wide use for domestic household hot-water heating and for space heating. The basic parts noted are a full-aperture absorber, transparent or translucent cover sheets, and an insulated box. The absorber is usually a sheet of high-thermal- conductivity metal with tubes or ducts either integral or attached. Its surface is painted or coated to maximize radiant energy absorption and in some cases to minimize radiant emission. The cover sheets, called glazing, let sunlight pass through to the absorber but insulate the space above the absorber to prohibit cool air from flowing into this space.
3. 3. Flat-plate collectors The insulated box provides structure and sealing and reduces heat loss from the back or sides of the collector. Flat-plate collectors will absorb energy coming from all directions above the absorber. Because of this characteristic, flat-plate collectors do not need to track the sun.
4. 4. Parabolic trough collectors Parabolic trough collectors use trough-shaped reflectors that concentrate sunlight on a receiver tube running along the reflector's focal line, achieving much higher temperatures than flat- plate collectors. These systems usually include a mechanical control system that keeps the trough reflector pointed at the sun throughout the day. Parabolic-trough concentrating systems can provide hot water and steam, and are generally used in commercial and industrial applications.
5. 5. Parabolic trough collectors Compound parabolic concentrating collectors (CPCCs) use mirrored surfaces to concentrate the sun's energy on an absorber called a receiver, similar to parabolic trough collectors. CPCCs achieve moderate concentration and moderately high temperatures but, unlike parabolic trough collectors, they can collect both direct and diffuse sunlight and don't require an automated sun-tracking system. CPCCs are being investigated for use in commercial applications where higher temperatures are required.
6. 6. Parabolic dish collectors Parabolic dish concentrating systems use parabolic dish shaped mirrors to focus incoming solar radiation onto a receiver that is positioned at the focal point of the dish. Fluid in the receiver is heated to high temperatures, around 750oC. This fluid is then used to generate electricity in a small Stirling or Brayton cycle engine, which is attached to the receiver. Parabolic dish systems are the most efficient of all solar technologies, at approximately 25% efficient, compared to around 20% for other solar thermal technologies.
7. 7. Parabolic dish collectors
8. 8. Solar Cell / Photovoltaic Cell A slab (or wafer) of pure silicon is used to make a PV cell. The top of the slab is very thinly diffused with an n dopant such as phosphorous. On the base of the slab a small amount of a p dopant, typically boron, is diffused. The phosphorous gives the wafer of silicon an excess of free electrons; it has a negative character. This is called the n-type silicon (n = negative). The n-type silicon is not chargedit has an equal number of protons and electronsbut some of the electrons are not held tightly to the atoms. They are free to move to different locations within the layer. The boron gives the base of the silicon a positive character, because it has a tendency to attract electrons. The base of the silicon is called p-type silicon (p = positive). The p-type silicon has an equal number of protons and electrons; it has a positive character but not a positive charge.
9. 9. Solar Cell / Photovoltaic Cell Where the n-type silicon and p-type silicon meet, free electrons from the n-layer flow into the p-layer for a split second, then form a barrier to prevent more electrons from moving between the two sides. This point of contact and barrier is called the p-n junction. If the PV cell is placed in the sun, photons of light strike the electrons in the p-n junction and energize them, knocking them free of their atoms.
10. 10. Solar Cell / Photovoltaic Cell A conducting wire connects the p-type silicon to an electrical load, such as a light or battery, and then back to the n-type silicon, forming a complete circuit. As the free electrons are pushed into the n-type silicon they repel each other because they are of like charge. The wire provides a path for the electrons to move away from each other. This flow of electrons is an electric current that travels through the circuit from the n-type to the p-type silicon.
11. 11. Hydropower Hydroelectric power comes from water at work, water in motion. To generate electricity, water must be in motion. This is kinetic (moving) energy. When flowing water turns blades in a turbine, the form is changed to mechanical (machine) energy. The turbine turns the generator rotor which then converts this mechanical energy into another energy form -- electricity. Since water is the initial source of energy, it is called hydroelectric power or hydropower for short.
12. 12. Hydropower Dams store water for later release for such purposes as irrigation, domestic and industrial use, and power generation. The reservoir acts much like a battery, storing water to be released as needed to generate power. The dam creates a head or height from which water flows. A pipe (penstock) carries the water from the reservoir to the turbine. The fast-moving water pushes the turbine blades, something like a pinwheel in the wind. The waters force on the turbine blades turns the rotor, the moving part of the electric generator. When coils of wire on the rotor sweep past the generators stationary coil (stator), electricity is produced.
13. 13. Flat Plate Solar Collectors
14. 14. Concentrating Solar Collectors
15. 15. Dish Collectors
16. 16. Solar Cell
17. 17. Natural Circulation Water Heating System A simple, small capacity, natural circulation system, suitable for domestic purposes is shown in figure. Two main components; the liquid flat- plate collector and the storage tank, located above the level of the collector. As the water is heated by the solar energy, it flows automatically to the top of the water and it is replaced by cold water from the bottom of the tank.
18. 18. Natural Circulation Water Heating System Hot water for use is withdrawn from the top of the tank. Whenever this is done, cold water automatically enters at the bottom. Most of the systems have capacities of 100 or 200 litres per day, and use one or two flat plate collectors having a surface area of 2m2 each. The temperature of the hot water delivered ranges from 50 to 70OC.
19. 19. Power generation using flat plate collectors Solar thermal power cycle can be classified as low (about 100OC), medium (about maximum up to 400OC) and high (above 400OC) temperature cycle. Low temperature systems use flat-plate collectors or solar ponds for collecting solar energy. The energy of the sun is collected by water flowing through the array of flat-plate collectors. The hot water at temperatures close to 100OC is stored in a well-insulated thermal storage tank. From here, it flows through a vapor generator through which the working fluid is also passed. The working fluid (low boiling point temperature) vapor at about 90OC at few atmospheric pressure leaves the vapor generator and flowing through a prime mover (turbine), a condenser and a liquid pump.
20. 20. Power generation using flat plate collectors A power generator is coupled with turbine and electric power is produced by generator. Up to 50KW power can be produced by this system .
21. 21. Photovoltaic System Application The system is an integrated assembly of modules and other components designed to provide a particular services, either alone or in conjunction of backup supply. A such simplest system for street lighting is shown in figure. The modules or array supplying a dc loads which can be stored in the battery. During at night, the dc power is supplied by controller through Inverter (which converts dc to ac voltage) to the light (load).
22. 22. Nuclear Power Plant The main components of a nuclear power plant are nuclear reactor, heat exchanger (steam generator), turbine, electric generator and condenser. The heat liberation in the reactor due to the nuclear fission of the fuel is taken up by the coolant circulating through the reactor core. Hot coolant leaves the reactor at top and then flows through the tubes of steam generator (boiler) and passes on its heat to the feed water. The steam produced is passed through the turbine and after work has been done by the expansion of steam in the turbine steam leaves the turbine and flows to the condenser. Pumps are provided to maintain the flow of coolant, condensate and feed water. The electric generator connected with the turbine produces the electric power.
23. 23. Nuclear Power Plant
24. 24. Nuclear Power Plant
25. 25. Nuclear Power Plant