ITRM20120111A1 - "HYBRID LIGHTING, NATURAL / ELECTRIC LIGHTING SYSTEM" - Google Patents

Description

Description of the industrial invention entitled: HYBRID LIGHTING SYSTEM, WITH NATURAL / ELECTRIC LIGHT;

The present invention substantially relates to the field of ambient lighting, capable of using both sunlight and artificial light, in order to guarantee the supply of the required quantity of light in the illuminated environment.

Basically, the invention provides for the use of sunlight as a source of light and of optical fiber as a means of propagation of light â € œfrom the Sunâ € to the environments to be illuminated.

According to the invention, the use of artificial light is provided as a supplement / integrating natural light in the event that the Sun is absent or covered by clouds.

The main advantages of using sunlight over artificial light are:

- reduction of atmospheric pollution produced by the consumption of electricity,

- chromatic quality of sunlight far more comfortable than artificial light, - absence of production of the heat that accompanies the light produced by the bulbs,

- possibility of use also in special environments (deposits with explosive gases, mines, ...) where the use of electricity is not recommended or prohibited for safety reasons.

State of the art

There are currently available on the market natural light systems that make use of optical fibers and solar tracking. The fibers distribute natural light inside buildings and can be integrated with existing artificial lighting systems. At the level of the ceiling light, the natural light conducted by the fiber can mix with the artificial light emitted by a bulb.

The well-known Parans Fiber Optic Skylight system is a system capable of transporting natural light inside buildings to places that are difficult to reach by solar radiation.

The system consists of an external panel with 64 Fresnel lenses that collects sunlight.

The lenses concentrate and collect the maximum of solar radiation available as they are equipped with a tracking system controlled by a computer placed inside, the solar radiation so concentrated is directed inside an optical fiber. 4 fiber optic cables come out of each panel, each of which can be up to 21 meters long.

The cables are distributed on walls and ceilings to bring natural light to internal ceiling lights which can be of different types, some of which combine natural light and artificial light.

Each hybrid ceiling light can be combined with a light sensor so that when there is enough natural light, the artificial light is automatically switched off.

Below is a summary of Parans products and their respective prices.

SolarPoint Lighting is another well-known system that distributes natural light inside buildings and is fully integrated with existing artificial light systems.

This system consists of a solar concentrator mounted on the roof, an approximately 15 m long plastic fiber optic cable and a plurality of hybrid ceiling lights.

Natural sunlight is concentrated in a small cable of optical fibers that conduct the light itself indoors where the hybrid ceiling lights diffuse the light itself. The maximum luminous flux is 25,000 lumens.

Through a controller, the power of artificial light is lowered or increased depending on the greater or lesser availability of natural light, thus favoring energy savings during daylight hours.

Considering all the installations, the aforementioned system boasts 1 million hours of experimentation.

Another known system, called Himawari, consists instead of a set of lenses and optical fibers.

The external collector, which is equipped with a solar tracking system with sensor and time mechanism, can collect solar radiation with maximum efficiency and transmit it inside optical fibers that allow it to be transported to the desired points.

The lenses are protected by a transparent acrylic screen which helps to shield the UV radiation, increasing the quality of the light.

In some installations, this system is equipped with photovoltaic cells intended for powering the tracker, reducing electricity consumption.

The following table shows a summary of the Himawari products available.

Number Of Number Of Light Total PowerLensesCables Receiving Lumen (lm) Usage Commercial

Projects198 33 14,035 63,360 15W Large Scale

Projects90 15 6,379 28,800 12W Mid Scale

Projects36 6 2,552 11,520 5W Small Scale

Projects12 2 851 3,840 2W Mid With

Solar Panels36 6 2,552 11,520 0 Small With

Solar Panels12 2 851 3.840 0

A better understanding of the invention will be obtained with reference to the following description and to the attached figures which illustrate, purely by way of example and not already imitative, a preferred embodiment.

In the figures:

Figure 1 shows some examples of currently known mixed solar / artificial lighting;

Figure 2 shows the well-known Parans system;

Figure 3 shows some hybrid ceiling lights available on the market

Figures 4A and 4B illustrate the well-known SolarPoint Lighting system;

Figures 5A and 5B illustrate the well-known Himawari system, with and without photovoltaic panels to power the tracker;

Figure 6 shows the elevations and plan of the container used during the experiments;

Figure 7 shows the pre-construction situation - relative to the positioning of the lamps;

Figure 8 shows the pre-operam situation of the illuminance values expressed in lux at the points of the calculation grid;

Figure 9A is a diagram of the fiber optic hybrid lighting system according to the present invention;

Figure 9B shows two views of the mixing device of the solar light with the artificial light used in the experiments;

Figure 10 is a Fresnel lens;

Figure 11 shows the solar tracker used in the experiments;

Figure 12 shows one end of the glass fiber optic cable;

Figure 13 is a graph of the attenuation as a function of the wavelength of the glass fiber;

Figure 14 illustrates the initial end of the glass fiber cable for the transport of solar radiation;

Figure 15 is a metal halide illuminator;

Figure 16 is a detail of the optical fiber case;

Figure 17 is a diagram showing the mixing of the light coming from the solar source with that coming from the artificial source according to the present invention;

Figure 18 is a cylindrical plexiglass bar used to make the mixer;

Figure 19 shows a detail of the PMMA optical fiber cable;

Figure 20 is a graph of the attenuation as a function of the wavelength of the PMMA fiber; Figures 26 to 30 show some construction details of the experimental prototype;

Figure 31 shows the SoG lens; And

Figure 32 schematically shows the tracker used in the experiments, which has two axes and the tracking is regulated by sensors.

According to a peculiar characteristic of the present invention, means 4 are provided for mixing the solar light with the artificial light, in which the source of artificial light, for example a lamp 3, is normally off and is switched on if it is necessary to supply the absence of the Sun (for example at night or in the event of an overcast sky).

Principle of operation

In the experiments, a hybrid fiber optic system was developed for the lighting of a container, assuming a future use for office use.

Figure 6 shows the front elevation of the container, the side and the plan view.

In the ante operam situation, the container is equipped with a traditional lighting system.

The following lamps are installed inside the room

- n. 1 OSRAM lamps 4050300774206 72085

Luminous flux: 2700 lm

Lamp power: 36.0 W

Equipment: 2 x L18W / 830 (Correction factor 1.000).

- n. 3 OSRAM lamps 4050300774237 72086

Luminous flux: 6700 lm

Lamp power: 72.0 W

Equipment: 2 x L36W / 830 (Correction factor 1.000).

A general lighting design can be carried out using the following formula:

E <N> × fL× <f> × <M>

m =

A [1]

Where is it:

<Em => average illuminance (lux)

<N => number of lighting fixtures

<f> L = luminous flux of each luminaire (lumen) <f> = utilization factor

<M> = maintenance factor

<A> = surface of the room to be illuminated (m <2>) We consider the total luminous flux equal to fTOT = N × fL

The [1] can be written as:

f à — Em = <TOT f> × <M>

A [2]

Knowing that the surface A of the container is equal to 30 m <2>, the total luminous flux <f TOT> installed is equal to 22,800 lumens and assuming: M = 0.8 and f = 0.4, we obtain an illuminance medium Empari at 243 lux.

Simulation with Dialux 4.8

To verify the assumptions made, a simulation was carried out with the Dialux 4.8 software.

Figure 7 shows the plan of the container with the position of the lamps (No. 1 indicates the OSRAM lamp 4050300774206 72085 and the No. 2 indicates the OSRAM lamp 4050300774237 72086)

The grid used has the dimensions of the plant of the room and has been positioned at a height of 0.85 m (height that is generally assumed for the work surface).

Figure 8 shows the values expressed in lux of the illuminance calculated in points 63 (9x7 grid) of the calculation grid.

The aforementioned values are also reflected in those actually measured, by means of a luxmeter, inside the room at various points located at a height of 0.85 m from the ground.

The average illuminance value obtained with the simulation on the work surface is equal to 261 lux. This value is comparable with that obtained by applying formula [2] for the general lighting engineering dimensioning of the room.

In the post-operam situation, the container is expected to be used as an office.

For this type of room, the EN 12464-1 standard indicates an average illuminance value, on a work surface placed at a height of 0.85 m from the ground, equal to 500 lux. This value is suitable for writing, typing, reading and data processing and for CAD stations.

Using formula [2] for the general lighting design by setting:

<Em - post> = 500 lux,

and using the same utilization and maintenance factors we have:

Em <-> post× A 500lux × 30m <2>

<f> TOT <-> post <=> = =

f × M0,4à — 0, 846,900 lm

By designing the lamps appropriately, it is possible to consider a utilization factor much higher than 0.4, for example 0.7, which implies a necessary luminous flux of about 26800 lm for the lighting of an office container. In this regard, it should be noted that the light emitted by the optical fiber can be used much more efficiently than that emitted by a light bulb, as the light emission occurs within a half-opening cone of about 30 degrees, which can be easily directed where desired. On the contrary, a traditional light bulb emits light over the whole space and this reduces its usability.

The lighting system according to the present invention is based on the transport of natural and artificial light energy through synthetic optical fiber in PMMA (PolyMethylMetaAcrylate) with point emission.

An extremely schematic representation of the invention is shown in figure 9A.

The invention includes the following main elements:

- solar concentrator 1 equipped with a solar tracking system;

- filter F for the abatement of the infrared component of concentrated solar radiation to be sent to the optical fibers;

- one or more 2S optical fibers in synthetic material or glass for the transport of concentrated sunlight;

- at least one source 3 of artificial light;

- mixer 4 for adding and mixing the solar and artificial light radiation, which receives sunlight from the optical and artificial fibers from the source;

- optical fiber bundle 5 at the mixer outlet;

- sensor for detecting the amount of solar radiation available;

- dimmable power supply for adjusting the power supply of the artificial light source.

In the illustrated embodiment example, the solar light radiation is collected through the concentrator which can be constituted by a Fresnel lens or optical conveyor, (Winston cone, parabola, etc.), and equipped with solar tracking means. Said light radiation is concentrated, filtered by the infrared component through the filter F and directed on the initial end of the optical fiber 2S placed in the focus of the concentrator.

The concentrated solar light radiation exiting from the final end of the fiber bundle 2S and the artificial light radiation of the lamp 3 are conveyed to the mixer 4 inlet.

The latter can be made up of a solid piece of highly transmissive material (PMMA) or a hollow piece with a highly reflective internal surface. The length of the mixer can be suitably sized in such a way as to ensure adequate mixing of the incoming sources.

For example, figure 9B shows an implementation of the mixer made in PMMA during the tests: the two light sources, circled in red (top) in the left figure, emit light at the entrance to the piece. The light from each source propagates inside the PMMA making total reflections on the walls (PMMA-air interface) and reaches the exit, indicated by the blue square (below), where the light leaves the material by refraction.

According to a peculiar characteristic of the invention, the last section of the mixer 4, that of square section, is of such length that the light introduced by the two sources has at least two total reflections. This guarantees light uniformity at the exit, as shown visually in the figure on the right.

In general, there are various `` sources '' of inefficiency that must be managed in the design phase:

(1) any roughness on the surface of the mixer

(2) any dirt on the surface of the mixer

(3) Fresnel reflections at the entrance and exit (4a) light rays incident on the entrance surface at too large angles

(4b) geometric shape with pronounced edges, sloping sides

(5) absorption / diffusion of light within the material.

These sources of inefficiency or dispersion are distinct issues that will be discussed below.

Problem (1) can be prevented by sanding the surfaces well and polishing them, for example, with fine Polish <®>. Problem (2) requires protecting the piece in a reflective paper package (such as Domopack <®>) or by wrapping it in a transparent film with a refractive index lower than that of PMMA (for example a film in THV, FEP or other fluorothermoplastic) so as to allow total reflection of light in the PMMA-film interface. The problem (3) can be minimized, and in principle even eliminated, by avoiding optical discontinuities (of refractive index) between the media crossed by the light, for example through the use of optical silicones.

Problems (4a) and (4b) have a common origin in the fact that the rays of light, in order to propagate inside the piece without escaping laterally, must affect the side faces at angles greater than what is defined in optics as the limit angle for the total reflection. Quantitatively, this angle is determined by Snell's law, once the refractive indices of the material within which the light propagates (PMMA in the embodiment shown here) and of the material at the interface (air in our embodiment) are known. In order to satisfy this requirement, it is necessary that the light entering the mixer hits the inlet surface with angles that are not too large (with respect to the normal to the inlet surface) and that the geometry of the mixer is such as not to introduce appreciable deviations of the light path (for example in the presence of edges) inside the mixer, such as to determine a lateral leakage. For example, in the case of a PMMA construction (refractive index n = 1.49) with fluorothermoplastic coating (refractive index n = 1.35) the incoming light with an angle greater than about 40 degrees (with respect to the normal to the entrance surface ) does not meet the optical requirement and will pop out of the part as soon as it hits the PMMA / Fluorothermoplastic interface. The incident light with an angle of 30 degrees will not escape, unless the side surface is tilted introducing an additional angle greater than 40-30 = 10 degrees to the direction of propagation of the light inside the blender.

The problem (5) is unfortunately unavoidable and depends on the properties of the vehicle and the dimensions of the piece. It can be reasonably kept small by choosing a material with a low concentration of impurities (for example, for the part shown in the figure, made of commercial grade PMMA, this loss is about 1.0%).

According to the invention, in front of the outlet of the mixer 4 is positioned the initial end of another bundle 5 of optical fiber cables, which constitute the final ducts of the transport system of the light radiation inside the room. .

The final ends of these cables 5, suitably distributed inside the room, will allow the light radiation to exit at the light points 6. These ends, which can be equipped with adequate diffusing terminations, constitute the light points 6 of the room.

The invention is preferably equipped with a system for regulating and controlling the power supply of the lamp which supplies the source of artificial light, which consists of said brightness sensor which detects the quantity of sunlight and which drives a dimmable power supply. which powers the lamp directly, or through a dedicated electronic control unit.

This allows you to automatically adjust the power supply of the artificial source based on the amount of solar radiation actually available, guaranteeing the desired level of illumination inside the room at all times, minimizing the consumption of the lamp.

A first prototype of the invention substantially realizes the previously indicated design scheme. The main purpose was to evaluate the implementation difficulties, as well as to have an indication of any unforeseen critical issues. Constructively, a Fresnel lens of

reasonable size was mounted on tracker

solar light of a known type, the captured sunlight is

focused on a fiberglass, mixed with

that coming from an artificial lamp (if

switched on) and distributed to the light points.

The first prototype includes the following elements

a) Solar concentrator

The device for the concentration of

solar radiation consists of a lens of

Square Fresnel with 280 mm side and 208 mm focal length.

(fig. 10)

b) Solar tracker

The selected solar tracker is a

two-axis tracker. The east-west pursuit is of

time type. (fig. 11)

In Table 1 below, the

characteristics of the solar tracking system.

Table 1:

Number of moving axles 2

Hourly limit angle 100Ëš, software and hardware limit Elevation angle 15 - 90Ëš

Motor type for clockwise angle Linear motor, 520 mm stroke Lift type Linear motor, 520 mm stroke Bar rotation speed 0.039 - 0.063 ° / s without load Hourly angle

Bar rotation speed of 0.052 - 0.062 ° / s without load elevation

0.5 ° tracking accuracy

c) Glass fiber optic cable, on the initial end of which the solar radiation is concentrated.

The solar radiation concentrated by the Fresnel lens is collected by a glass fiber optic cable with an optical diameter of 8 mm made up of 6160 monofibers of 0.1 mm (Figure 12), the initial end of which is placed in correspondence with the focus of the lens itself. .

Figure 13 shows the attenuation of the light radiation as a function of the length of the optical fiber.

Table 2 below shows the characteristics of the glass fibers that make up the cable.

Table 2:

Material High quality optical glass Attenuation 150 dB / km Diameter of the single ones

monofibre <0.1 mm>

Numerical aperture 0.5

Megolon sheath (self-extinguishing PVC) The cable is positioned so that the initial section, equipped with a terminal and suitably machined (Figure 14), is perpendicular to the focal length of the lens.

The cable section has been chosen suitably large, in order to take into account the tracking inaccuracy of the solar tracker and any external factors that could cause the fire to fall outside the initial section of the cable.

d) Artificial source

The artificial source consists of a specific illuminator for use with glass optical fibers with a 150W metal halide lamp which has a concentrated light radiation output of approximately 5200 lm (Figure 15).

e) Bundle of glass optical fibers, on the initial end of which the radiation of the artificial source is concentrated.

The radiation emitted by the artificial source is concentrated on the initial end of a bundle of glass fibers with a total optical diameter of 27 mm made up of 50 glass fiber cables each with an optical diameter of 3.3 mm (each cable has its own vault made up of 1820 monofibres of 0.07 mm).

The fibers are of the same type of glass as those of the cable used for the transport of solar radiation (see Table 2).

The cables are collected in a single union (Figure 16) which allows you to connect the fiber bundle to the illuminator

f) Plexiglass mixer for mixing solar and artificial radiation

The final end of the 2S optical fiber cable which carries the solar radiation and that of the 2A beam which carries the artificial radiation are collected in a single outlet which has the sum of the two radiations (Figure 17).

In order to make the radiation resulting from the sum of solar radiation and artificial radiation uniform, a mixer is positioned at the outlet of the nozzle.

The mixer consists of a plexiglass cylinder with a diameter of 30 mm and a length of 100 mm (Figure 18).

g) Bundle of PMMA optical fibers exiting the mixer

The ends of another bundle 5 of optical fibers in PMMA consisting of n. 8 cables with 9.85 mm optical diameter each consisting of 75 synthetic 1 mm monofibers (Figure 19).

Table 3 shows the characteristics of the PMMA fibers that make up cable 5.

Table 3: technical characteristics of PMMA fibers

PMMA material

Attenuation 150 dB / km

Diameter of the single ones

monofibre <0.1 mm>

Numerical aperture 0.51

Self-extinguishing PVC sheath

Figure 20 is a graph showing the attenuation of the intensity of the light entering the fiber, as a function of the wavelength of the light entering the PMMA fiber

A variant of the invention relates to a different concentrator in which the use of a (multi) Fresnel lens of the Silicon on Glass (SoG) type is provided to focus the light on PMMA optical fiber (instead of glass as in the case of the first prototype). After measuring the efficiency of the concentrator, the problem of giving angular tolerance to the system was faced: according to the invention, this was done by placing an oversized fiber optic cable (circular 6mm diameter) in the focus of each lens. ) compared to the optical image of the Sun (circle with a diameter of about 3mm). In this way, alignment errors (perpendicularity of the lens with respect to the sun's rays) of about -0.5 degrees are advantageously tolerated.

Figure 26 shows this variant in which the concentrator is housed on a solar tracker. In this case, the elements that make up the concentrator are the following:

- SoG lens with overall dimensions 480 mm x 780 mm, divided into a matrix of lenses with dimensions of 150 mm x 150 mm and nominal focal length of 200 mm (fig.

31)

- ITEM aluminum profile frame

- perforated aluminum plate with threaded holes arranged in a 3 x 5 matrix equidistant at 150 mm from each other (like the optical centers of the lens) - brass cable gland with biconical ogive system

The lens is supported by the aluminum frame, integrally with the solar tracker. The perforated aluminum plate is placed on the plane of the lens foci and the cable glands to which the optical fibers are fixed are screwed onto these holes.

It is interesting to note that the solar tracker is preferably of the type with active sensor tracking in order to provide greater precision in positioning with respect to the Sun.

In addition, the optical fibers consist of a band of small fibers with a total section of 6 mm, and optical filters are provided that eliminate the infrared component of solar radiation by reflecting it, in order to prevent thermal damage to the head of the optical fiber on which it beats. the concentrated light of the Sun.

Figure 26 is a view of the tracker with lens and fiber optic strips positioned under the focuses of the lens, behind the infrared radiation filter:

Figure 27 shows a detail of the infrared radiation filter, while figure 28 shows a detail of the fiber end illuminated by the light. Note that the light comes out laterally from the fiber, this leakage is mainly due to the light that hits the empty interstices between one fiber and the other of the end and consequently comes out.

Figure 29 below presents five light points inside the room to be illuminated, while figure 30 shows a prototype chandelier to which the light points are fixed.

The tracker used has two axes and the tracking is regulated by sensors (fig. 32).

The following table shows the technical characteristics of the tracker.

Table 4

Finally, it is interesting to observe that, since one of the two inputs of the mixer is reserved for artificial light, this involves the use of at least one light bulb of some kind that runs on electricity.

Since said bulb is located close to the mixer, it follows that electric cables for powering the bulb are inevitably required, which are also located close to the mixer. If the latter is placed outside the room to be illuminated, then the electric power cables of the light bulb are also located outside the mixer.

Advantageously, the absence of electric cables inside the room to be illuminated makes the invention usable also in all environments in which the use of electric current is prohibited or inadvisable, such as in mines, explosives deposits, etc.

Therefore, a further peculiar feature of the invention is that of being able to install the light mixer and the related artificial light source outside the room to be illuminated, so that only the optical fiber enters the room itself to provide the lighting. ™ desired lighting, both day and night.

LEGEND:

1 solar concentrator

2S optical fibers that transport concentrated sunlight from the concentrator to the mixer 2A optical fibers that transport artificial light from its source to the mixer

3 source of artificial light, for example a known type of lamp

4 mixer of sunlight with artificial light

5 optical fibers that carry concentrated solar / artificial light from the mixer to the lighting bodies

6 lighting bodies

F filter that reduces / eliminates infrared radiation from solar radiation sent to the optical fibers

Claims (13)

CLAIMS: 1. Hybrid lighting system, with natural / electric light, of the type comprising means for capturing / concentrating (1) the sunlight, preferably installed on solar tracking means, which convey the solar radiation into one or more optical fibers carrying the sunlight up to lighting bodies arranged inside the rooms to be illuminated, characterized by the fact of including, in combination: - means (F) for the abatement of the infrared component of the concentrated solar radiation to be sent to the optical fibers (2S); - one or more optical fibers (2S) in synthetic material or glass for the transport of concentrated sunlight; - at least one source (3) of artificial light of a known type; - at least one mixing device (4) for adding and mixing the solar and artificial light radiation, to receive sunlight from the optical fibers (2S) and artificial light from the source (3); - at least one bundle of optical fibers (5) exiting the mixer (4) to bring the solar / artificial light to one or more lighting bodies (6). 2. Plant according to the preceding claim, characterized in that said means for reducing the infrared component of solar radiation consist of a filter (F) such as for example a film of material opaque to IR radiation. 3. Plant according to the preceding claim, characterized in that it comprises a dimmable power supply for adjusting the power supply of the source (3) of artificial light. 4. Plant according to claim 1, characterized in that it comprises at least one sensor for detecting the quantity of solar radiation available. 5. Plant according to claims 3 and 4, characterized in that it comprises electronic means for adjusting the power supply of the artificial light source (3) as a function of the data detected by the solar radiation sensor. 6. Plant according to claim 2, characterized in that said concentrator (1) which collects the solar light radiation is constituted by a Fresnel lens or other optical conveyor such as Winston cone, parabola, etc., and is installed on suitable for solar tracking vehicles. 7. Plant according to the preceding claim, characterized in that said light radiation, concentrated and filtered of the infrared component, is directed on the initial end of the optical fiber (2S) placed in the focus of the concentrator. 8. Plant according to the preceding claim, characterized in that the concentrated solar light radiation exiting from the final end of the fiber bundle (2S) and the artificial light radiation of a lamp (3), are conveyed to the mixer ( 4). 9. Plant according to the preceding claim, characterized in that said mixer (4) of solar and artificial light is constituted by a solid piece of highly transmissive material (PMMA) or by a hollow piece with a highly reflective internal surface; the length of the mixer (4) being suitably sized in such a way as to ensure adequate mixing of the incoming sources. 10. Plant according to the preceding claim, characterized in that the last section of the mixer (4) is of such length that the light introduced by the two sources has at least two total reflections; thus obtaining the guarantee of luminous uniformity at the exit. 11. System according to one of the preceding claims, characterized in that said mixer (4) and said source (3) of artificial light are installed externally to the environment to be illuminated, so that only the optical fiber (5) exiting the mixer enters the environment itself to provide the desired lighting. 12. Plant according to one of the preceding claims, characterized in that said concentrator (1) is substantially constituted by one or more Fresnel lenses of the Silicon on Glass (SoG) type to focus the light on PMMA optical fiber. 13. Plant according to the preceding claim, characterized in that, in order to give angular tolerance to the system, it provides for the provision of an optical fiber cable with an oversized section in the focus of each lens compared to the optical image of the Sun, thus obtaining the possibility of tolerating alignment errors, ie perpendicularity of the lens with respect to the sun's rays, of about -0.5 degrees.