Light pipes or tubes

  • View
    759

  • Download
    4

Embed Size (px)

DESCRIPTION

Solar energy is freely available and it is simple wasted.. if we utilize this energy we can save electrical energy upto some extent..

Text of Light pipes or tubes

  • 1. Deccan college of engineering and technology Seminar on Light pipes By Mohd Rizwan Basharat B.E (4/4) (160310736305)

2. Contents Introduction Existing model Working Features Future enhancement journals 3. Over the past few years considerable research has been undertaken on the use of light pipes as transport devices or light emitters. The majority of systems in use employ electric lamps or sun tracking devices as light sources and thus rely on expensive equipment to capture, transport and distribute light. Recent interest has focused on passive light pipes as a means of lighting interiors. These devices operate according to the same physical principles as electric or solar systems to transport and distribute light but, due to their simplicity, are cheaper to construct and maintain. Introduction 4. Light tubes or light pipes are physical structures used for transporting or distributing natural or artificial light for the purpose of illumination, and are examples of optical waveguides. In their applications to daylighting, they are also often called tubular daylighting devices, sun pipes, sun scopes, or daylight pipes. Light pipes may be divided into two broad categories: hollow structures that contain the light with a reflective lining, and transparent solids that contain the light by total internal reflection. 5. Existing model The light pipes literally transport sunlight to the indoors, with the help of an ingeniously devised technology of light trapping and enhancement mechanisms. To understand how the system works, one has to just imagine sound travelling down a pipeline by hitting its walls, and gaining strength from its echoes. A Polycarbonate dome with two deflection panels sloping against each other, acts as the light collector on the roof. 6. The deflection panels are arranged so as to absorb maximum light from the morning and evening Sun, and least from the mid-day so as to avoid the heat. The silver metal oxide used to coat the inside of the pipe reflects and re-reflects the light, till the crisscross of light travels down the pipe and hits the Light Diffuser which in turn controls the brightness depending on the requirement. Daylight use of 10 hours per day can be ensured by using the light pipes, says 7. An office filled with sunlight 8. working The structure of the dome allows it to capture light from the sun when high in the sky and even at low angles, maximizing the light throughput. As the sun rises, sunlight enters the light pipe through an acrylic diffuser. Inside, the light bounces off reflectors and is focused to the center 9. The deflection panels are arranged so as to absorb maximum light from the morning and evening Sun, and least from the mid-day so as to avoid the heat. The silver metal oxide used to coat the inside of the pipe reflects and re- reflects the light, till the crisscross of light travels down the pipe and hits the Light Diffuser which in turn controls the brightness depending on the requirement. 10. Features Roof dome Diffusers Flexible tube Tube with an Adhesive Reflective Foil on an Aluminium Surface. Mirrored Reflective Surface 11. Roof dome Roof dome are made from Bohemian Crystal and practically dont age compared to plastic domes. Crystal has great capacity for collecting daylight when there is cloud cover. Crystal domes dont distort the natural colors of daylight. The surface of crystal is very hard and smooth and smog and dust doesnt stick to it as on plastic. Crystal domes dont yellow after several years on a roof and continue to emit light for decades 12. Diffuser Lightway chose sodium- potassium glass for the ceiling diffusers of incoming light. Other producers make this feature from plastic, which means faster aging and the danger of color distortion in the incoming daylight. There is a difference visible to the eye between plastic and glass diffusers. 13. Flexible tube Amount of light: due to physical laws, it delivers very little light. For this kind, the name dark pipe has been created . Construction companies like to use it as a substitute for a light pipe because its price is a third of a light pipe which shines. It works only in direct sunlight. 14. Tube with an Adhesive Reflective Foil on an Aluminium Surface 15. Disadvantages You cant see the outdoors through a solar tube. Of limited value if you dont live in a sunny climate. Condensation can form if you live in a humid area. If they are not straight, the effect is compromised. Add-ons such as dimmers jack up the cost quickly. When water leaks from a light pipe on cold days and leads to heat loss in winter 16. Advantages Much more energy efficient than lights Better insulated than skylights or windows Can bring light to interior rooms that do not have outside walls More secure than standard windows. No thief can break into your home through a solar tube Can be installed in wet areas such as bathrooms and indoor pools because they dont draw on any electricity. They work well in closets, too. Much less expensive than skylights 17. Future enhancement Fluorescence based system: fluorescent polymer layers in a flat panel capture short wave sunlight, particularly ultraviolet light, generating red and green light, respectively, which is guided into the interior of a building. There, the red and green light is mixed with artificial blue light to yield white light, without infrared or ultraviolet. This system, which collects light without requiring mobile parts such as a heliostat or a parabolic collector, is intended to transfer light to any place within a building. . 18. The fluorescent emitted light travels to the edges of the panels by total internal reflection. Normally all edges of the panels but one (the extraction edge) are covered with reflective material to redirect exiting light back inside the panel until it finds its way to the extraction edge. In the product developed by the fluorescent panels are connected to a PMMA flexible guide at the extraction edge, where the light of different wavelengths is mixed and travels to the extraction point or luminary by total internal reflection, finally leaving the guide as white light in buildings. 19. Solar panels The great challenge for the lightpipe industry is to produce 24 hour energy-free lighting. By using small solar panels during the day to charge solar batteries to provide power to LEDs embedded into the surround of a lightpipe diffuser. As external light levels drop, the batteries will illuminate the LEDs. PIRSs will activate the lighting 20. Journal Passive Roof Mounted Light Pipes When the configuration of a building permit that is when the number of floors from the roof to the space to be illuminated by daylight is limited, passive roof-mounted light pipes offer an effective means of transferring natural daylight from the roof of a building to spaces at lower levels. These light pipes typically comprise a clear polycarbonate dome at the upper end, a zenithal or vertical circular pipe section, and a diffuser section as exit port for daylight at the lower end. Figure 1(a) illustrates the configuration of a roof-mounted pipe. Such light pipes are commercially available. 21. References JouSimulation of Transmission of Daylight through Cylindrical Light Pipes S. Chirarattananon1,*, V.D. Hien1, P. Chaiwiwatworakul1, and P. Chirarattananon2 1 Energy Program, Joint Graduate School of Energy and Environment, King Mongkuts University of Technology Thonburi, Bangkok, Thailandrnal of Sustainable Energy & Garcia Hansen, V. and Edmonds, I. ISES 2003 1 NATURAL ILLUMINATION OF DEEP-PLAN OFFICE BUILDINGS: LIGHT PIPE STRATEGIES Garcia Hansen, V1. and Edmonds, I2. 1.COLAB, School of Design and Built Environment, Queensland University of Technology (QUT). P.O. Box 2434Environment 1 (2010) 97-103 22. RefrenceJournal of Sustainable Energy & Environment 1 (2010) 97-103 Copyright @ 2010 By Journal of Sustainable Energy and Environment 103 [3] Scartezzini JL, Courret G, Anidolic daylighting systems, Solar Energy 73/2 (2002) 123-135. [4] Beltran LO, Lee ES, Selkowitz SE, Advanced optical daylighting systems: light shelves and light pipes, Journal of the illuminating engineering society 26 (1997) summer 91-106. [5] CIE, CIE-173:2006. Tubular Daylight Guidance Systems (2006). [6] Reas M, editor IESNA Lighting Handbook: Reference and Application (2000) 9th edition, Ch. 8: Daylighting, 8.1-8.28. Illuminating Engineering Society of North America. [7] Lam CJ, Li DHW, Daylight availability in Hong Kong and energy implications, International Journal of Ambient Energy 17/2 (1996) 79-88. [8] Zain-Ahmed A, Sopian K, Zainol Abidin Z, Othman MYH, The availability of daylight from tropical skies-a case study of Malaysia, Renewable Energy 25 (2002) 21-30. [9] Chirarattananon S, Chaiwiwatworakul P, Pattanasethanon S Daylight availability and models for global and diffuse horizontal illuminance and irradiance for Bangkok, Renewable Energy 26 (2002) 69-89. [10] Mahdavi A, Pal V, Lam KP, Empirical evaluation of solar radiation, sky luminance and daylight prediction models, Journal of Illumination Engineering Society 28/1 (1999) 30-36. [11] Perez R, Seals R, Ineichen P, Menicucci D, A new simplified version of the Perez diffuse irradiance model for tilted surfaces. Solar Energy 39/3 (1987) 221-231. 23. Thankyou