Deccan college of engineering and technology

Seminar onLight pipes

ByMohd Rizwan Basharat

B.E (4/4) (160310736305)

Contents

• Introduction• Existing model• Working• Features• Future enhancement• journals

• 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

• 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.

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.

• 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

An office filled with sunlight

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

• 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.

Features• Roof dome• Diffusers

• Flexible tube• Tube with an Adhesive Reflective Foil on an

Aluminium Surface.• Mirrored Reflective Surface

Roof dome• Roof dome are made from

Bohemian Crystal and practically don’t age compared to plastic

domes.• Crystal has great capacity for

collecting daylight when there is cloud cover.

• Crystal domes don’t distort the natural colors of daylight.

• The surface of crystal is very hard and smooth and smog and dust doesn’t stick to it as on plastic.

• Crystal domes don’t yellow after several years on a roof and

continue to emit light for decades

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.

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.

Tube with an Adhesive Reflective Foil on an Aluminium Surface

Disadvantages• You can’t see the outdoors through a

solar tube.

• Of limited value if you don’t 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

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 don’t draw on any electricity. They work well in

closets, too.• Much less expensive than

skylights

Future enhancementFluorescence 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. • .

• 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.

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

Journal• Passive Roof Mounted Light PipesWhen 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.

References• JouSimulation of Transmission of Daylight through

Cylindrical Light PipesS. Chirarattananon1,*, V.D. Hien1, P. Chaiwiwatworakul1, and

P. Chirarattananon21 Energy Program, Joint Graduate School of Energy and Environment, King Mongkut’s 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

RefrenceJournal of Sustainable Energy & Environment 1 (2010) 97-103

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[5]CIE, CIE-173:2006. Tubular Daylight Guidance Systems (2006).

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Thankyou