Unit 2-REGS.ppt
- 1. DEPARTMENT OF ELECTRICAL ENGINEERING V-SEMESTER RENEWABLE ENERGY GENERATION SYSTEM UNIT II SOLAR ENERGY
- 2. UNIT III:- SYLLABUS Principles, scope and applications of solar Energy 1 Applications of Solar Energy 2 3 4 2 5 flat plate collectors solar radiation measurement solar power generation.
- 3. UNIT-3 SPECIFIC OBJECTIVE / COURSE OUTCOME •THREE PHSFORMER •MAINTENANCE OF TRANSFORMER •METHODS 3 1 Understand different applications of Solar energy 2 Understand solar radiation measurement The student will be able to: 3 Understand types of solar collector
- 4. 4 LECTURE 1 Solar Energy
- 5. 5 LECTURE 1 Solar Energy • Energy produced by the sun • Clean, renewable source of energy • Harnessed by solar collection methods such as solar cells • Converted into usable energy such as electricity • Solar energy is the most readily available source of energy. • It is free. • It is also the most important of the non-conventional sources of energy because it is non-polluting. What is Solar Energy?
- 6. 6 LECTURE 1 Solar Energy In the recent yeas there has been an extensive increase in the use of solar energy. For ex: Heating, cooling, power generation etc. The radiation from sun is in the form of Direct (Beam)radiation and Diffused radiation. Hence at a particular location we need to measure the irradiance data so that we can predict the performance of solar energy.
- 7. Radiation is energy that comes from a source and travels through space and may be able to penetrate various materials.
- 8. The bandwidth of radiant energy — from long wave to short wave. It consists of radio waves, microwaves, visible light (red and violet), ultraviolet rays, X rays, and gamma rays.
- 9. Definition Solar constant is defined as the rate at which solar energy arrives at the top of the atmosphere. This is the amount of energy received from the Sun in unit time on a unit of area perpendicular to the Sun’s direction at Earth’s mean distance from the Sun. • It is most accurately measured from satellites where atmospheric effects are absent •The value of the constant is approximately 1.366 kilowatts per square metre (1367 w/m2). •The “constant” is fairly constant, increasing by only 0.2 percent at the peak of each 11-year solar cycle •solar constant increases by about 10 percent every billion years.
- 10. Solar Radiation at the Earth's Surface • The solar radiation incident on the Earth's atmosphere is relatively constant, the radiation at the Earth's surface varies widely due to: 1. atmospheric effects, including absorption and scattering; 2. local variations in the atmosphere, such as water vapour, clouds, and pollution; 3. latitude of the location; and 4. the season of the year and the time of day. • The above effects have several impacts on the solar radiation received at the Earth's surface. These changes include variations in the overall power received, the spectral content of the light and the angle from which light is incident on a surface. In addition, a key change is that the variability of the solar radiation at a particular location increases dramatically. The variability is due to both local effects such as clouds and seasonal variations, as well as other effects such as the length of the day at a particular latitude.
- 21. 21 Types solar radiation measurement devices • PYRHELIOMETER a) The Angstrom Pyrheliometer b) The Abbot silver disc c) Eppley Pyrheliometer • PYRANOMETER a) For measuring global radiation b) For measuring diffuse radiation
- 22. 22 PYRHELIOMETER • PYRHELIOMETER It is an instrument which measure direct or beam radiation falling on a surface normal to the sun’s rays.
- 23. 23 PYRHELIOMETER
- 24. 24 Pyranometer • PYRANOMETER It is an instrument which measures either global or diffuse radiation falling on a horizontal surface over a hemispherical field of view.
- 25. 25 Pyranometer PYRANOMETER FOR MEASURING GLOBAL RADIATION
- 27. 27 Pyranometer 1) When sunlight falls on a pyranometer, the thermopile sensor produces a proportional response typically in 30 seconds or less: the more sunlight, the hotter the sensor gets and the greater the electric current it generates. 2) The thermopile is designed to be precisely linear (so a doubling of solar radiation produces twice as much current) and also has a directional response: it produces maximum output when the Sun is directly overhead (at midday) and zero output when the Sun is on the horizon (at dawn or dusk). 3) This is called a cosine response (or cosine correction), because the electrical signal from the pyranometer varies with the cosine of the angle between the Sun's rays and the vertical.
- 28. 28 Eppley Pyranometer • EPPLEY PYRANOMETER The Pyranometer when provided with a shadow band to prevent beam radiation from reaching the sensing element measures diffuse radiation only.
- 31. 31 Sunshine Recorder • The duration of bright sunshine is measured by means of a sunshine recorder. The sun’s rays are focused by a glass sphere to point on a card strip in a groove in a spherical bowl mounted concentrically with the sphere. Whenever there is a bright sunshine the image formed is intense enough to burn a spot on the card strip. Through the days the sun moves across the sky the image moves along the strip. Thus the burnt space whose length is proportional to the duration of sun shine is obtained on the strip.
- 35. 35 Solar water heater • Fuel saving: A 100 litres capacity SWH can replace an electric geyser for residential use and saves 1500 units of electricity annually. • Environmental benefits SWH of 100 litres capacity can prevent emission of 1.5 tons of carbon di oxide per year. • Life : 15-20 years The payback period depends on site of installation,utilization pattern and fuel replaced. Payback period : 3-4 years when electricity is replaced 4-5 years when furnace oil is replaced 5-6 years when coal is replaced
- 36. 36 Basic photovoltaic system A Basic photovoltaic system for power generation
- 37. 37 Solar collector • Solar energy collectors are special kind of heat exchangers that transform solar radiation energy to internal energy of the transport medium. • The major component of any solar system is the solar collector. • This is a device which absorbs the incoming solar radiation, converts it into heat, and transfers this heat to a fluid (usually air, water, or oil) flowing through the collector.
- 38. 38 Types Of Solar collector 1. Non-concentrating or stationary . 2. Concentrating. 1)Non-concentrating or stationary A non-concentrating collector has the same area for intercepting and for absorbing solar radiation, whereas a sun- tracking. They can produce heat at low and medium temperatures (up to 100 °C). 2) Concentrating. Concentrating, or focusing, collectors intercept direct radiation over a large area and focus it onto a small absorber area .They can produce heat at high temperatures
- 39. 39 Stationary Collectors • Solar energy collectors are basically distinguished by their motion, i.e. stationary, single axis tracking and two axis tracking, and the operating temperature. • These collectors are permanently fixed in position and do not track the sun
- 40. 40 Types Of collectors 1. Flat plate collectors (FPC). 2. Stationary compound parabolic collectors (CPC). 3. Evacuated tube collectors (ETC).
- 42. 42 Flat plate collector Exploded view of a flat-plate collector.
- 43. 43 Flat plate collector 1. Glazing 2. Tubes, fins, or passages 3. Absorber plates 4. Headers or manifolds 5. Insulation 6. Container or casing Components of FPC
- 44. 44 Flat plate collector 1. Glazing :- The glazing cover has the function of isulating the solar collector from external environmental conditions and allowing solar radiation to pass through. It is usually made up of a single sheet of solid glass approximately 4mm thick. This part is only present in glazed flat plate solar collectors, designed to minimize heat loss. 2. Tubes, fins, or passages :- To conduct or direct the heat transfer fluid from the inlet to the outlet. 3. Absorber plates :- The absorbing plate is the element that intercepts solar radiation inside the collector and is responsible for transforming solar energy into thermal energy. The absorbing plate is usually formed by a metallic foil, usually copper (an excellent thermal conductor), that darkens. Dark, matte bodies capture solar radiation better than any other colour. 4.Headers or manifolds :- To admit and discharge the fluid.
- 45. 45 Flat plate collector 5.Insulation :- The insulation reduces heat losses from the inside of the collector - specifically from the absorbing plate - to the outside. It is usually made up of synthetic foam sheets (polyurethane, cyanides, fiberglass, etc.) located on the sides and the back of the solar panel. To minimize the heat loss from the back and sides of the collector. 6.Container or casing :- To surround the above mentioned components and keep them free from dust, moisture, etc.
- 46. 46 Flat plate collector Flat-plate collectors are the most common solar collectors for use in solar water-heating systems in homes and in solar space heating. A flat-plate collector consists basically of an insulated metal box with a glass or plastic cover (the glazing) and a dark-colored absorber plate. Solar radiation is absorbed by the absorber plate and transferred to a fluid that circulates through the collector in tubes. In an air-based collector the circulating fluid is air, whereas in a liquid-based collector it is usually water . Flat collectors can be mounted in a variety of ways, depending on the type of building, application, and size of collector. Options include mounting on a roof, in the roof itself, or free. Working Principle
- 47. 47 Flat plate collector 1. Flat-plate collectors will absorb energy coming from all directions above the absorber. 2. flat-plate collectors do not need to track the sun 3. Simple in design 4. No moving part 5. Requires little maintenance 6. Less cost Advantages
- 48. 48 Solar Dryer
- 49. 49 Solar Dryer Direct solar dryers expose the substance to be dehydrated to direct sunlight. Historically, food and clothing was dried in the sun by using lines, or laying the items on rocks or on top of tents. In Mongolia cheese and meat are still traditionally dried using the top of the ger (tent) as a solar dryer. In these systems the solar drying is assisted by the movement of the air (wind) that removes the more saturated air away from the items being dried. More recently, complex drying racks and solar tents[ were constructed as solar dryers.
- 50. 50 Solar Still
- 51. 51 Solar Still A solar still distills water with substances dissolved in it by using the heat of the Sun to evaporate water so that it may be cooled and collected, thereby purifying it .. In a solar still, impure water is contained outside the collector, where it is evaporated by sunlight shining through clear plastic or glass. The pure water vapour condenses on the cool inside surface and drips down, where it is collected and removed. ... The sun's energy heats water to the point of evaporation.
- 52. 52 Solar Cooker
- 53. 53 Solar Cooker A solar cooker is a device which uses the energy of direct sunlight(generated from sunlight) to heat, cook or pasteurize drink and other food materials. Most solar cookers work on the basic principle: Sunlight is converted to heat energy, that is used for cooking. ... Evacuated tube solar cookers use a highly insulated double-wall glass tube for the cooking chamber, and do not require large reflectors. Fuel: sunlight. Sunlight is the fuel. A solar cooker converts solar energy into heat, which is used to cook food kept in the cooking utensil. Solar cookers also enable some significant processes such as pasteurization and sterilization
- 56. 56 SUMMARY Principles, scope and applications of solar Energy solar radiation measurement flat plate collectors Applications of Solar Energy solar power generation.
- 57. 57 REFERENCES Reference Books : 1. Non conventional sources of Energy by G.D.Rai 2. Solar Energy : Principles of Thermal collection and storage 3 rd edition by S.P.Sukhatme,J.K.Nayak 3. Energy Technology:Nonconventional Renewable and Conventional by S. Rao and B.B Parulekar 4. Renewable Energy Sources Basic Principles and Applications by G. N. Tiwari and M. K. Ghoshal . References Web: 1. En.wikipedia.org
- 58. 58 Solar Cell