WO2018083509A1

WO2018083509A1 - Solar radiation concentrator

Info

Publication number: WO2018083509A1
Application number: PCT/HR2017/000003
Authority: WO
Inventors: Vladimir Grlica
Original assignee: Vladimir Grlica
Priority date: 2016-11-02
Filing date: 2017-04-20
Publication date: 2018-05-11
Also published as: HRP20161427A2

Abstract

The Solar Radiation Concentrator with Two Coupled Parabolic Mirrors consists of: a large parabolic mirror (1) that has an opening (7) on its vertex (4), and a small parabolic mirror (2) that is mechanically connected to the large parabolic mirror, so that their axes (6) match, and their focus (3) is at the same point. The mirrors coupled in this way achieve concentrated solar radiation through the opening (4) on the large mirror's vertex, if the axis of the mirror (6) is directed towards the Sun. This system of parabolic mirrors is set on a mechanism that constantly directs the axis of the mirrors (6) towards the Sun. The mechanism has two flat mirrors inbuilt. One flat mirror (9) is set at the intersection of the axis of parabolic mirrors (6) and the horizontal axis of vertical rotation (8) and at an angle of 45° in relation to both axes. Another flat mirror (10) is set at the intersection of the horizontal axis of vertical rotation (8) and the vertical axis of horizontal rotation (1 1) and at an angle of 45° in relation to both axes. At output, the concentrated solar radiation is always parallel with the vertical axis of horizontal rotation (11), regardless of the position of the Sun in the sky.

Description

SOLAR RADIATION CONCENTRATOR

DESCRIPTION OF THE INVENTION

Area to Which the Invention Relates

The use of solar heat, solar collectors with elements for concentration of Sun radiation F24J2/0 and solar thermal systems not provided elsewhere F24J2/42.

Technical Problem

From ecological point of view, Sun is an ideal source of energy. However, a large drawback is that the sunshine is not present at all times, i.e. the Sun is not visible at night and during cloudy weather. This problem may be resolved by storing Sun's energy at times when there is solar radiation and using it later from the place of storage when it's not there.

Solar energy is essentially an electromagnetic radiation, and it cannot be stored. It is necessary to convert solar energy into a form of energy suitable for storage and later on in a form that is suitable for use.

The most appropriate form of energy storage is the thermal energy and especially thermal energy at high temperatures (temperatures between 500 and 800 °C). This kind of energy can be simply used at such high (or somewhat lower) temperatures (for the various types of furnace), or at substantially lower temperatures (e.g. for heating buildings or the preparation of hot water), but also it can be converted into electrical energy (well known technology of thermal power plants).

In order to use the Sun energy at higher temperatures, Concentrators can be applied. Solar Concentrators are devices that increase the density of solar radiation, thus creating higher temperatures on the receiver.

The receiver needs to be placed into the focal point of the Concentrator, so the problem is to transfer heat energy from the receiver to the consumer unit (or storage). This problem was, until now, addressed in one of the following two ways: by setting the consumer unit together with the receiver in the focus, or by using the

transmission fluid for heat transfer from the receiver to the consumer unit.

Current Technical Solutions

There are in principle four known ways of using solar energy with Concentrators. These are:

1. ) Parabolic Trough. It is a mirror made of polished metal, shaped so that in one plane it has a shape of a parabola, and in the second plane it is flat and set in an East-West direction and angled towards the Sun. This ensures that the Sun rays are reflected from the mirrors into the focal line during the entire day. A tube filled with working fluid is then placed into this focal line. The working fluid circulates from the receiver to the consumer unit, which is in this case most often a water steam generator. Possible working fluid temperature ranges from 150 to 350 °C, which represents a limitation of this system, as it provides relatively low temperatures.

2. ) Concentrating Fresnel Reflector. It is a Concentrator, much like the previous solution described, with the difference that instead of the elongated parabolic mirror it uses a mirror made up of multiple smaller strip mirrors that are set up in parabolic shape and reflect the solar radiation on the receiver (tube) placed in the focal line. The problem of this solution is the same as described under 1 ·).

3. ) Solar Power Tower. Receiver is mounted at the top of the tower and

connected with the consumer unit. Around the tower, higher number of flat mirrors are positioned and equipped with a mechanism which moves them continuously, so that they constantly reflect solar radiation to the receiver. The disadvantage of this solution is a reduced efficiency, which is a consequence of the changing effective surface of flat mirrors throughout the day due to the change of angle under which Sun rays come onto the mirror, as well as a consequence of the insufficient precision of directing the mirrors. This system is suitable for the storage of heat energy.

4. ) Dish Stirling. The mirror is made in the shape of a parabolic dish, with a

receiver positioned in the focus of the mirror. This receiver is connected with a Stirling engine, and the Stirling engine is connected to an electricity generator. The reflector is constantly bi-axially managed (rotation), so that the Sun rays constantly fall in parallel to the axis of the reflector. This system has demonstrated the greatest efficiency in practice so far: it delivers efficiency of solar-to-electrical energy of 34%. A disadvantage of this system is its impossibility of storing thermal energy. Exposing the Essence of the Invention

The primary goal of the invention is to achieve a concentrated solar radiation at one fixed place and with a fixed direction, regardless of the position of the Sun on the sky during the day.

The secondary goal of the invention is to achieve high solar radiation intensity sufficient for obtaining high temperatures on the receiver, in principle over 750 °C, and therefore be adequate for usage as a heat source in thermal plants for production of electrical energy, or usage in thermal facilities for various other purposes.

A further goal of the invention is to enable transfer of the concentrated solar radiation - through a system of fixed set of mirrors or througha light waveguide - to a receiver located at around 100 m distance.

Another goal of the invention is to allow the usage of solar energy both when there is Sun radiation (e.g. during a sunny day) and when this radiation is not present (e.g. during a cloudy day or during the night). To achieve this goal it is necessary to provide an efficient heat storage by using either already known solutions or potential new inventions.

The Concentrator consists of two coupled parabolic mirrors, one with a larger diameter and one with a smaller diameter, and they are coupled so that their axes coincide, and their focus is at the same point. The smaller mirror must have a smaller distance from its vertex to the focus. The larger mirror has an aperture (opening, hole) at its vertex, with diameter that is somewhat larger than the diameter of the smaller mirror. This sort of coupling of parabolic mirrors provides a concentrated solar radiation through the opening in the vertex of the large parabolic mirror at all times when the joint axis of the mirrors is directed towards the Sun. The radiation obtained in this way is mutually parallel and parallel to the axis of the mirror. Ratio of concentration is equal to the ratio between surface areas of large and small parabolic mirrors.

The Concentrator is equipped with a device for the bi-axial rotation, which enables tracking the Sun throughout the day. Bi-axial rotation consists of a horizontal and a vertical rotation. The vertical rotation is performed around a horizontal axis, which is located behind the vertex of the large parabolic mirror. The horizontal rotation is performed around a vertical axis which is set asymmetrically in relation to the axis of the mirrors.

At the intersection of the axis of the mirrors and the axis of vertical rotation, there is a flat mirror set at an angle of 45 ° in relation to both axes. This flat mirror is fixed to a carrier of the large parabolic mirror and tilts together with the carrier. The flat mirror reflects radiation shining through the opening on the large parabolic mirror's vertex. This reflection is parallel with the axis of vertical rotation at all times, regardless of vertical rotation stage.

The mechanism of horizontal rotation must have an opening (holeopening around the vertical axis of horizontal rotation. This opening must be either equally sized or larger than the opening on the large parabolic mirror's vertex. The flat mirror Is set at the intersection of the axis of vertical rotation and the axis of horizontal rotation, and at an angle of 45 ° in relation to both axes. There, the flat mirror is fixed to a rotating part of the horizontal alignment mechanism. This mirror reflects a parallel radiation comming from the previous mirror and directs it parallel to the axis of horizontal rotation, right through the opening in the mechanism of horizontal rotation.

A Brief Description of the Drawings

1. ) Drawing on Fig.1 is a cross-section view through the vertical plane of the common axis of parabolic mirrors (CROSS SECTION A-A on Fig.2).

2. ) Drawing on Fig.2 is a cross-section view through the horizontal plane - through the vertex of the large parabolic mirror.

3. ) Drawing on Fig.3 is a cross-section view through the plane that is common for axes of horizontal and vertical rotation of the parabolic reflectors (CROSS-SECTION B-B on Fig.1).

Application Mode of the Invention

This invention allows for solar energy to be used as thermal energy at high temperatures. Such thermal energy usage is possible either instantly or it can be stored in insulated thermal containers and used later on, when there is no Sun. This kind of energy can be used to power the furnaces of various types and purposes, such as for food preparation (for professional cooking facilities, bakeries, etc.), or for various industrial thermal processing, or for the production of electricity (solar thermal power plants). This invention can be produced and used in various sizes to result in a power ranging from 1 KW or less, up to 100 KW and more, depending on need.

It is also possible to connect more of these Concentrators to a single user with a simple system of flat mirrors or with a light vaweguide. The temperature can be changed by selecting an appropriate concentration ratio, which is achieved by selecting a different ratio of parabolic mirrors' surface areas, as well as by selecting different receiver types or designs. A Detailed Description of One of the Application Modes of the Invention

The Concentrator consists of two parabolic mirrors: a large parabolic mirror (1) that has an opening (7) on its vertex (4), and a small parabolic mirror (2) which is mechanically connected to the large parabolic mirror in a way that their axes (6) match, and their focus is at the same point. Such a mutual coupling allows for passing of a parallel beam of concentrated solar radiation through the opening in the vertex of the large parabolic mirror and in parallel with the common axis of both mirrors, if this axis is directed towards the Sun. The system of parabolic mirrors is set on a mechanism that constantly directs joint axis towards the Sun. This mechanism allows for vertical rotation in the wrist of the vertical rotation (13) around the horizontal axis of the vertical rotation (8), which is located behind the mirror. This mechanism also allows for horizontal rotation around the vertical axis (11), that is asymmetrical in relation to the axis of parabolic mirrors (6) and that crosses the horizontal axis of vertical rotation (8).

At the intersection of the axis of parabolic mirrors (6) and the horizontal axis of vertical rotation (8), a flat mirror (9) is positioned and attached to the large parabolic mirror at an angle of 45 ° in relation to both axes. This ensures that a parallel beam of concentrated radiation that passes through the opening (7) at the vertex of large parabolic mirror falls right on that flat mirror (9), and reflects in parallel with the horizontal axis of vertical rotation (8). At the intersection of the horizontal axis of vertical rotation (8) and the vertical axis of horizontal rotation (11), and at an angle of 45 ° in relation to both axes, the second flat mirror (10) is set and fixed to the rotating part of the horizontal rotation device (12). With such a set of flat mirrors, the system achieves a concentrated solar radiation being always in the same place, which is in parallel with the vertical axis of horizontal rotation, regardless of the stage of vertical and horizontal rotation of parabolic mirrors, provided that the axis of the mirror is directed towards the Sun. This invention enables for a concentrated solar energy to be either used on the vertical axis of the horizontal rotation, or delivered to a remote place of usage - via a system of fixed mirrors or a light vaweguide.

List of Labels Used

1. ) Large parabolic mirror

2. ) Small parabolic mirror

3. ) Common focus of the large and small parabolic mirrors

4. ) Vertex of the large parabolic mirror

5. ) Sun rays

6. ) Common axis of the large and small parabolic mirrors

7. ) Opening in the vertex of the large parabolic mirror

8. ) Horizontal axis of vertical rotation

9. ) Flat mirror A

10. ) Flat mirror B

11. ) Vertical axis of horizontal rotation

12. ) Rotating part of the horizontal rotation device

13. ) Vertical rotation joint

14. ) Carrier of the large parabolic mirror

15. ) Stationary part of the horizontal rotation device

Claims

I CLAIM

1. The Concentrator is a system of two parabolic mirrors, one of which is small

(2) and the other large (1) with opening (7) on the peak (4) wherein mirrors are set up in the way that their axis (6) match and their focus is at the same point

(3) . The Sun rays (5) that fall on the large mirror (1) in parallel to the axis (6), reflect on the small mirror (2). From there rays are reflected in a beam parallel to the axis of the mirror (6) and pass through the opening (7) on the vertex (4) of the large mirror (1).

2. The Concentrator as under claim 1 wherein it is set on a mechanism for

vertical rotation in the joints (13) around horizontal axis (8) that is located behind the large parabolic mirror and horizontal rotation around vertical axis (1 1) that is set up asymmetrically in relation to the mirrors' axis (6), with an opening (16) around this axis (1 1).

3. The Concentrator as under claim 2 wherein at the intersection of the axis of parabolic mirrors (6) and the horizontal axis of the vertical rotation (8) a flat mirror (9) is set at an angle of 45° in relation to both axes and fixed to a carrier (14).

4. The Concentrator as under claim 3 wherein at the intersection of the vertical axis of horizontal rotation (1 1 ) and the horizontal axis of vertical rotation (8) another flat mirror (10) is set at an angle of 45° in relation to both axes and is fixed to a rotating part of the horizontal rotation device (12).