rus
Issue #6/2015
S.Samokhvalov, O.Gorbachev, A. Klimenko
Use of Fiber-Optic Technology for Lighting Devices
Use of Fiber-Optic Technology for Lighting Devices
The simplest optical fiber the lighting device can convert energy sunlight energy into another form without additional costs and pass in a dark room on the fiber optic cable. This article describes design, calculations and test results and computer models of some nodes device.
Теги: hybrid fiber optic devices lighting engineering гибридные оптоволоконные устройства светотехника
W
orld costs for lighting are on average 20% of the electricity consumed. It is strange to see a light bulb on in the bathroom of a residential apartment, or in the hallway, when the sun is shining outside. However, a lamp in each standard apartment is on, it consumes power, and we are used to it.
In Volgograd, Krasnodar, Astrakhan and other southern cities, where almost 300 sunny days a year [1], and the temperature on the upper floors in summer reaches 60C, in the premises without windows, the lighting fixtures are switched on during daytime generating rather heat than light.
Of course, it is possible to accumulate solar energy, converting it into electricity using solar cells. And the resulting electrical energy can be used for illumination of the premises with the help of lighting fixtures.
However, double conversion of energy is inevitable, so there are the huge losses. It is known that solar cells have a low efficiency. Single-crystal silicon has an efficiency of 17–20%, while polycrystalline and amorphous silicon has less than 10%. If you continue to use the resulting energy for lighting using incandescent lamps, the efficiency of which is less than 10%, the lighting will use 1–2% of the input power. And the spectrum of light waves of the lighting equipment is far from the solar spectrum.
Using the lens concentrators, it is possible to reduce the cost per unit of installed capacity of photovoltaic cells only by 2–3 times [2].
To illuminate the upper floors with natural light, skylights can be used, but they have complex and expensive construction.
Hybrid fiber-optic units of direct sunlight are relatively new technology [3]. Hybrid fiber-optic units can light up to 300 m2 of living or office space, and are intended for the direct supply of natural daylight into the lighted premises [4]. The unit consists of a parabolic mirrors (collector, 2), focusing sun rays to the input end of the fiber optic cable, conveying light in the lighted premises. A part of the light energy is converted into electrical energy, which is accumulated and used for the system of positioning and power supply of the lamps during nighttime. The positioning system turns the collector during the daytime, constantly directing it to the sun. The presence of complex kinematic components for tracking the sun requires external power supply from the network or obtained from the conversion of light energy into electrical energy. The hybrid fiber-optic unit is also complicated and expensive. Its price goes up to 16 thousand dollars, and the cost of installation works range from 500 to 2000 dollars. However, despite the impressive prices, the experts predict that about 1 million of hybrid fiber-optic systems will be sold in the US in 2020. In the coming years, it is planned to implement 5000 hybrid fiber-optic lighting systems. This will save 50 million kW/h of electricity annually. According to a comparative analysis, performed by the US experts, the average cost of electricity from these systems is significantly lower than the cost of electricity offered in the unregulated energy market.
It is obvious that the demand for a system of direct natural lighting of buildings in the world will grow in proportion to the reduction in the cost of these systems, with an increase in power and decrease in the loss of fiber optics. These systems will be able to provide high-rise buildings with natural light from the first floor. Even nowadays, the hybrid fiber-optic systems are installed at public universities in San Diego, Las-Vegas, Nevada, in a number of Wall-Mart supermarkets and elsewhere. In the US, the buyers of hybrid systems receive 30% discount inclusive VAT. In Russia there is no tax relief for those who decide to invest the funds in energy efficiency, "green" technology.
In this research we conducted the studies aimed at creating a simple, reliable and inexpensive lighting apparatus using natural sunlight. For directing at the sun, the collector device uses the effect of thermal expansion (fig. 3). This reduces the cost by a factor of hundreds. A polymer fiber cable is not only used for the transport of light, but also to direct the collector to the sun. The collector may be fabricated from plastic in a sealed housing with metalized inner surface. It concentrates the sunlight by a lens, a large and a small mirror. The collector is secured to the focon, together they narrow light flux to a size of the input end of the optical fiber. Focon is bent under the influence of temperature, like a bimetallic plate and constantly directs the collector to the sun, similar to well-known sunflower.
For this purpose, the outer focon shell consists of translucent, heat-sensitive segments separated from each other by thermally insulating material. The focon input end is always perpendicular to the sun rays. Therefore, almost all light energy penetrates the focon, and is not reflected from it. The shift of the light spot from the center of the input end to the heat-sensitive segments leads to their heating, bending the focon, resulting in the deflection of the collector towards the sun.
The power of the infrared radiation entering the focon is significantly reduced when using the aberration. "Cold" sunlight of visible range is transported into a dark room through the polymer optical fiber (POF) without any conversion to other forms of energy. The device does not consume electricity, which ensures its high efficiency. With good transparency of polymeric optical fibers, the efficiency of the device is between 50–80%, depending on the length of the cable and its quality.
The reliability of the lighting device is very high. The parts of the lighting device hardly heat up, thus achieving a high level of operational safety. The novelty of the work is confirmed by two patents [5–7].
To determine the optimal size of the device and the calculation of its parameters, its computer model has been created. Fig. 4 shows a 3D-computer model of the collector.
By the number of input, output and scattered rays the collector efficiency is determined. In good reflective properties of the mirrors, its value can be increased to 95%. Also, the optimal size of focon was determined; the material for its outer layer of heat-sensitive segment was selected. Fig. 5 shows the dependence of the number of rays that have passed from focon to POF on the length of focon. According to the results of calculations, the prototype devices have been elaborated.
Figure 6 with the help of computer modeling shows the propagation of a light wave in the focon in 3 planes. The computer model consists of a focused light flux source (1) of the focon (2) that focuses sunlight, directing it to the optical fiber (3). During the study, the optimum aperture was established to minimize the reflected and scattered light, and to maximize light output in the optical cable.
The authors of this work have been carried out preliminary tests of the reduced layout of the proposed lighting device. A round glass convex lens with a diameter of 10 cm was used for focusing the solar light flux. The luminous flow was transported via a polymer fiber with a diameter of 1 mm and a length of 10 m. In this manner, a small room (4 m 2) without windows was lit. And though the light level was very small (about 15 lux), such lighting is quite acceptable for a man’s orientation in space. In this experiment, the infrared spectrum of light flux was not cut, so the melting of the plastic coating of the input end of the optical fiber occurred. However, such problems can be avoided during transportation of the "cold" sunlight.
The power level of the light flux can be increased by an order of magnitude, even when using a 1 mm fiber. To this end, the diameter of the front lens of the collector should be increased to 25–30 cm. Nowadays polymer optical fibers with a diameter up to 3 mm are produced in Russia. Their use will allow illuminating with natural sunlight a relatively large room during daytime with no electricity costs. Retail price of such simple and reliable lighting devices is hundreds of times less than the price of their hybrid fiber counterparts, and mass production can be totaled to 3–7 thousand RUB only.
A large guaranteed demand for these simple and reliable devices can be predicted. The sales in Russia alone could reach several million pieces. Furthermore, such devices allow for safe lighting in hazardous areas (mines, chemical plants), as well as in humid areas (pools, saunas, winter gardens, aquariums, etc.). These devices can be considered as remote windows or remote skylights with cable transportation of light flux. It is fair to say that they only work during the daytime and in sunny weather.
There is no doubt that the incandescent lamps, fluorescent lamps, LED and other lamps must give a way to sunlight wherever possible.
orld costs for lighting are on average 20% of the electricity consumed. It is strange to see a light bulb on in the bathroom of a residential apartment, or in the hallway, when the sun is shining outside. However, a lamp in each standard apartment is on, it consumes power, and we are used to it.
In Volgograd, Krasnodar, Astrakhan and other southern cities, where almost 300 sunny days a year [1], and the temperature on the upper floors in summer reaches 60C, in the premises without windows, the lighting fixtures are switched on during daytime generating rather heat than light.
Of course, it is possible to accumulate solar energy, converting it into electricity using solar cells. And the resulting electrical energy can be used for illumination of the premises with the help of lighting fixtures.
However, double conversion of energy is inevitable, so there are the huge losses. It is known that solar cells have a low efficiency. Single-crystal silicon has an efficiency of 17–20%, while polycrystalline and amorphous silicon has less than 10%. If you continue to use the resulting energy for lighting using incandescent lamps, the efficiency of which is less than 10%, the lighting will use 1–2% of the input power. And the spectrum of light waves of the lighting equipment is far from the solar spectrum.
Using the lens concentrators, it is possible to reduce the cost per unit of installed capacity of photovoltaic cells only by 2–3 times [2].
To illuminate the upper floors with natural light, skylights can be used, but they have complex and expensive construction.
Hybrid fiber-optic units of direct sunlight are relatively new technology [3]. Hybrid fiber-optic units can light up to 300 m2 of living or office space, and are intended for the direct supply of natural daylight into the lighted premises [4]. The unit consists of a parabolic mirrors (collector, 2), focusing sun rays to the input end of the fiber optic cable, conveying light in the lighted premises. A part of the light energy is converted into electrical energy, which is accumulated and used for the system of positioning and power supply of the lamps during nighttime. The positioning system turns the collector during the daytime, constantly directing it to the sun. The presence of complex kinematic components for tracking the sun requires external power supply from the network or obtained from the conversion of light energy into electrical energy. The hybrid fiber-optic unit is also complicated and expensive. Its price goes up to 16 thousand dollars, and the cost of installation works range from 500 to 2000 dollars. However, despite the impressive prices, the experts predict that about 1 million of hybrid fiber-optic systems will be sold in the US in 2020. In the coming years, it is planned to implement 5000 hybrid fiber-optic lighting systems. This will save 50 million kW/h of electricity annually. According to a comparative analysis, performed by the US experts, the average cost of electricity from these systems is significantly lower than the cost of electricity offered in the unregulated energy market.
It is obvious that the demand for a system of direct natural lighting of buildings in the world will grow in proportion to the reduction in the cost of these systems, with an increase in power and decrease in the loss of fiber optics. These systems will be able to provide high-rise buildings with natural light from the first floor. Even nowadays, the hybrid fiber-optic systems are installed at public universities in San Diego, Las-Vegas, Nevada, in a number of Wall-Mart supermarkets and elsewhere. In the US, the buyers of hybrid systems receive 30% discount inclusive VAT. In Russia there is no tax relief for those who decide to invest the funds in energy efficiency, "green" technology.
In this research we conducted the studies aimed at creating a simple, reliable and inexpensive lighting apparatus using natural sunlight. For directing at the sun, the collector device uses the effect of thermal expansion (fig. 3). This reduces the cost by a factor of hundreds. A polymer fiber cable is not only used for the transport of light, but also to direct the collector to the sun. The collector may be fabricated from plastic in a sealed housing with metalized inner surface. It concentrates the sunlight by a lens, a large and a small mirror. The collector is secured to the focon, together they narrow light flux to a size of the input end of the optical fiber. Focon is bent under the influence of temperature, like a bimetallic plate and constantly directs the collector to the sun, similar to well-known sunflower.
For this purpose, the outer focon shell consists of translucent, heat-sensitive segments separated from each other by thermally insulating material. The focon input end is always perpendicular to the sun rays. Therefore, almost all light energy penetrates the focon, and is not reflected from it. The shift of the light spot from the center of the input end to the heat-sensitive segments leads to their heating, bending the focon, resulting in the deflection of the collector towards the sun.
The power of the infrared radiation entering the focon is significantly reduced when using the aberration. "Cold" sunlight of visible range is transported into a dark room through the polymer optical fiber (POF) without any conversion to other forms of energy. The device does not consume electricity, which ensures its high efficiency. With good transparency of polymeric optical fibers, the efficiency of the device is between 50–80%, depending on the length of the cable and its quality.
The reliability of the lighting device is very high. The parts of the lighting device hardly heat up, thus achieving a high level of operational safety. The novelty of the work is confirmed by two patents [5–7].
To determine the optimal size of the device and the calculation of its parameters, its computer model has been created. Fig. 4 shows a 3D-computer model of the collector.
By the number of input, output and scattered rays the collector efficiency is determined. In good reflective properties of the mirrors, its value can be increased to 95%. Also, the optimal size of focon was determined; the material for its outer layer of heat-sensitive segment was selected. Fig. 5 shows the dependence of the number of rays that have passed from focon to POF on the length of focon. According to the results of calculations, the prototype devices have been elaborated.
Figure 6 with the help of computer modeling shows the propagation of a light wave in the focon in 3 planes. The computer model consists of a focused light flux source (1) of the focon (2) that focuses sunlight, directing it to the optical fiber (3). During the study, the optimum aperture was established to minimize the reflected and scattered light, and to maximize light output in the optical cable.
The authors of this work have been carried out preliminary tests of the reduced layout of the proposed lighting device. A round glass convex lens with a diameter of 10 cm was used for focusing the solar light flux. The luminous flow was transported via a polymer fiber with a diameter of 1 mm and a length of 10 m. In this manner, a small room (4 m 2) without windows was lit. And though the light level was very small (about 15 lux), such lighting is quite acceptable for a man’s orientation in space. In this experiment, the infrared spectrum of light flux was not cut, so the melting of the plastic coating of the input end of the optical fiber occurred. However, such problems can be avoided during transportation of the "cold" sunlight.
The power level of the light flux can be increased by an order of magnitude, even when using a 1 mm fiber. To this end, the diameter of the front lens of the collector should be increased to 25–30 cm. Nowadays polymer optical fibers with a diameter up to 3 mm are produced in Russia. Their use will allow illuminating with natural sunlight a relatively large room during daytime with no electricity costs. Retail price of such simple and reliable lighting devices is hundreds of times less than the price of their hybrid fiber counterparts, and mass production can be totaled to 3–7 thousand RUB only.
A large guaranteed demand for these simple and reliable devices can be predicted. The sales in Russia alone could reach several million pieces. Furthermore, such devices allow for safe lighting in hazardous areas (mines, chemical plants), as well as in humid areas (pools, saunas, winter gardens, aquariums, etc.). These devices can be considered as remote windows or remote skylights with cable transportation of light flux. It is fair to say that they only work during the daytime and in sunny weather.
There is no doubt that the incandescent lamps, fluorescent lamps, LED and other lamps must give a way to sunlight wherever possible.
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