ES2601222B1 - Fresnel linear solar concentrator with triple movement - Google Patents

Abstract

Fresnel linear solar concentrator with triple movement comprising a fixed structural system (1) anchored that supports a secondary concentrator system (3) which balances in the North-South direction and a mobile structural system (2) that balances in the North-South direction. The mobile structural system (2) supports a primary concentrator system (4) comprising a certain number of mirrors (5) or rows of mirrors (5), with the possibility of balancing in the East-West direction. The secondary concentrator system (3) comprises a tube or absorber tubes (9) that collects the energy projected by the mirrors (5) and transports it. # Of application in those sectors in which energy generation equipment is manufactured or used thermal from radiation, as in those of the building, or for water purification or desalination.

Description

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DESCRIPTION

Fresnel linear solar concentrator with triple movement.

The present invention relates to a Fresnel linear solar concentrator (CLF) equipped with three movements, comprising a fixed structural system, a mobile structural system with the possibility of balancing in the North-South direction pivoting with respect to a primary axis in the East direction. West, a primary concentrator system composed of a certain number of rows of mirrors with the possibility of balancing in the East-West direction pivoting with respect to a reflector axis in the North-South direction and a secondary concentrating system with the possibility of balancing in the North direction -Sur pivoting with respect to a secondary axis in East-West direction. The secondary concentrator in turn comprises a tube or absorber tubes through which a heat transfer fluid circulates that collects the energy projected by the mirrors and transports it.

The invention results from application in those sectors in which equipment for the generation of thermal energy from radiation is manufactured or used, as is the case of the building sector, in which the simultaneous production of electricity and heat is needed. (for heating and / or refrigeration and / or heating of sanitary water), that is, trigeneration. It also results from application in water purification and water desalination.

State of the art

In 2014, 54% of the world's population lives in urban areas and collectively consume 75% of the world's resources. In 2050, 66% of the world's population is expected to be urban (United Nations, World Urbanization Prospects: Revision 2014, 2014). Today, the most urbanized regions include North America (82% live in urban areas in 2014), Latin America and the Caribbean (80%) and Europe (73%) (United Nations, World Urbanization Prospects: Revision 2014, 2014). Therefore, it is essential to minimize energy consumption in the urban environment.

In the European Union (EU), the building sector represents one of the largest consumers of energy. In particular, it represents more than 40% of final energy consumption (Directive 2010/31 / EC, 2010. On the Energy Performance of Buildings). Therefore, the EU promotes a series of guidelines in order to encourage the use of energy alternatives for buildings (Directive 2009/28 / EC, 2009. On the promotion of the use of energy from renewable sources). These guidelines encourage the study of the combined production of heat and electricity (CHP). On the other hand, there are several different definitions of a nearly zero or zero net energy building (NZEB). The EU, in Directive 2010/31 / EU (Directive 2010/31 / EC, 2010. On the Energy Performance of Buildings), describes an almost zero energy building as a building with a very high energy efficiency, where "the almost zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced at the site of the facility or nearby. " The zero energy balance may include the energy used for heating, ventilation and air conditioning, lighting and the use of electrical equipment.

There are several renewable energy systems that can be used in the building sector for the production of electricity and heat (I. Ceron, E. Caamano-Martln, F.J.

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Neila State-of the-art of building integrated photovoltaic products, Renewable Energy, vol. 58, pp. 127-133, 2013; S.A. Kalogirou, Solar thermal collectors and applications, Progress in Energy and Combustion Science, vol. 30, pp. 23 1-295, 2004). Solar thermal and photovoltaic systems are currently the most widely used, especially in regions where annual solar radiation is high, as is the case in the countries of southern Europe. In these regions, the number of installations in the form of domestic solar hot water systems and photovoltaic systems connected to the network are increasing. In addition, work is being done on systems that generate domestic hot water, heat for heating or cooling through air conditioning systems. Therefore, solar energy technologies are called to play a viable alternative to fossil energy systems.

Thermal solar systems can be basically classified into two types of solar collectors: collectors without concentration and concentration collectors. A collector without concentration has the same area to intercept the sun's rays as for the absorption of solar radiation. On the contrary, in a concentration manifold, the absorption zone is much smaller than the primary reception zone, thus increasing! solar irradiation on the concentrator. Collectors without concentration normally lack movement and remain fixed in the same position, so they do not have a solar tracking system. Instead, the collectors with concentration do have movement. Another difference is the operating temperature. A possible classification is shown in Table 1 (S. Kalogirou, The potential of solar industrial process heat applications, Applied Energy, vol. 76, pp. 337-361,2003).

Table 1. Types of Solar Collectors

 Movement

 Type dc Collator T (° C)

 Motionless

 Pianos Collectors 30-80

 Evacuated Tube Collectors

 50-200

 Compound parabolic collectors

 60-240

 One axis

 I-ineales concentrators Fresnel 60-250

 Parabolic trough concentrators

 60-300

 Two axes

 100-500 parabolic discs

 Heliostat fields

 150-2000

There are many studies on the use of Flat Collectors in buildings, such as: F. Motte, G. Notton, C. Cristofari, J.L. Canaletti, A building integrated solar collector: Performances characterization and first stage of numerical calculation, Renewable Energy, vol. 49, pp. 1-5, 2013; L. Navarro, A. Gracia, S. Colclough, M. Browne, S.J. McCormack, P. Gric ths, L.F. Head, Thermal energy storage in building integrated thermal systems: A review. Part 1. active storage systems, Renewable Energy, vol. 88, pp. 526-547, 2016; C. Good, I Andresen, A.G. Hestnes, Solar energy for net zero energy buildings. A comparison between solar thermal, PV and photovoltaic.thermal (PV / T) systems, Solar Energy, vol. 122, pp. 986-996, 2015; or G. Tsalikis, G. Martinopoulos, Solar energy systems potential for nearly net zero energy residential buildings, Solar Energy, vol. 115, pp. 743-756, 2015. However, there are not so many studies based on the use of CLF. For example, these concentrators can be used in domestic water heating (Sultana, G.L. Morrison, G. Rosengarten, Thermal performance of a

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novel rooftop solar micro-concentrating collector, Solar Energy, vol. 86, pp. 1992-2000, 2012) or in the cooling / heating of buildings (P. Bermejo, F.J. Pino, F. Rosa, Solar absorption cooling plant in Seville, Solar Energy, vol. 84, pp. 1503-1512, 2010).

Several CLF configurations have been proposed in the literature (MJ Montes, C. Rubbia, R. Abbas and JM Martlnez-Val, A comparative analysis of configurations of linear Fresnel collectors for concentrating solar power, Energy, vol. 73, pp. 192 -203, 2014). In the conventional CLF, there are two main parts: the primary concentrator system and the secondary concentrator system. The primary concentrator system consists of a structure, without the possibility of movement, in which the rows of mirrors oriented in the North-South direction are arranged. These mirrors are endowed with an East-West rotation movement. The secondary concentrator system consists of a concentrator cavity and an absorber tube or tubes, with no possibility of movement. The concentrating cavity serves to concentrate the solar rays reflected by the primary concentration system in the absorber tube that do not affect it and thermally isolate the absorber tube. The absorber tube is located inside the secondary concentrator system, and may be composed of one or more tubes through which the heat transfer fluid circulates. The secondary concentrator system is located at a certain height above the primary concentrator system. There are currently 15 power generation plants in the world using this configuration, such as, for example, the PE1 plant in Puerto Errado, Murcia (1.4 MW), the PE2 plant in Puerto Errado, Murcia (30 MW) or Reliance Areva CSP 1, India (125 MW). This configuration is used by large-scale CLFs. The length of the absorber tube is usually hundreds of meters long, distributed in several rows. Due to the length of the absorber tube the secondary concentrator system has no movement. With this configuration, and in the North-South direction, the absorber tube has a length greater than the rows of mirrors, to avoid that in the North-South direction the reflected rays of the primary concentrator system impact outside the absorber tube. In this type of plants the surface available for installation is not a problem.

In the Fresnel Linear Compact Concentrator (CCLF) (D. Milis and GL Morrison, Compact linear Fresnel re thermal solar powerplants, Solar Energy, vol. 68, no. 3, pp. 263-283, 2000) the secondary concentrator system , without the possibility of movement, it is divided into two parts, located on each side of the primary concentration system, so that the consecutive mirrors permanently point to different absorber tubes.

There are other possible configurations for the CLF model (horizontal, vertical or inclined) that have been studied by several research groups. For example, in D. Milis and G. L. Morrison, Compact linear Fresnel thermal solar reflector powerplants, Solar Energy, vol. 68, no. 3, pp. 263-283, 2000 there are two linear receivers in separate towers. In R. Abbas, J. Munoz and J. M. Martlnez-Val, Steady-state thermal analysis of an innovative receiver for linear Fresnel reflectors, Appt. Energy, vol. 92, pp. 503-515, 2012 the receiver consists of a bundle of tubes parallel to the rows of mirrors. In R. Abbas, M. J. Montes, M. Piera and J. M. Martlnez-Val, Solar radiation concentration features in linear Fresnel reflector arrays, Energy Convers Manag, vol. 54, pp. 133-144, 2012 analyze the use of different optical designs, including circular-cylindrical mirrors and parabolic-cylindrical mirrors with different reference positions.

In all these mentioned configurations, the primary concentrator system and the secondary concentrator system lack movement, so that a

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large area available for the implantation of all the elements of the equipment to be effective in solar captation. This is mainly due to the variation in the relative position of the sun in its daily traffic and in its seasonal movement, which causes the direction of the sun's rays to change over time. In addition, due to this lack of movement, there is a loss of energy called "end of tube loss" that is due to the fact that during a large part of the solar collection period the solar rays do not affect the ends of the absorber tube (Y. Elmaanaoui, D. Saifaoui, Parametric analysis of end loss efficiency in linear Fresnel reflector, Renewabte and Sustainable Energy Conference, 2014, pp. 104-107, 2014; S. Pu, C. Xia, End-effect of linear Fresnel collectors, Conf PPEEC, pp. 1-4, 2011). There are other types of applications, such as in the building sector, in which the available area is a parameter that limits the use of these configurations. In addition, the lack of movement in the primary and secondary concentrator systems means that the secondary concentrator system has to be disposed a certain distance from the primary concentrator system, which limits the installation of other CFLs.

Description of the invention

The present invention relates to a CLF with triple movement to collect and concentrate solar energy on a heat transfer fluid that transports it to where it can be used.

For the purposes of this invention and its description, pivoting, pivoting, balancing or balancing refers to the movement of rotation of an object around a pivot axis, in a plane perpendicular to it. The axis is normally defined by its direction with respect to cardinal points. The balancing movement is usually defined by a balancing direction perpendicular to the pivot axis, designated with cardinal points.

An object of the present invention therefore relates to a Fresnel linear solar concentrator comprising:

- A fixed structural system, anchored to a stable surface, which supports a secondary concentrator system and a mobile structural system. The secondary concentrator system can be balanced in the North-South direction by pivoting respect to a secondary axis oriented in the East-West direction.

- A mobile structural system with the possibility of balancing in the North-South direction pivoting with respect to a primary axis in the East-West direction, which supports a primary concentrating system.

- A primary concentrator system that in turn comprises one or several mirrors arranged in one or several rows, where each of the mirrors swings in an East-West direction pivoting with respect to a reflector axis in the North-South direction to follow the apparent movement of the sun during successive day periods. These mirrors reflect solar radiation on the secondary concentrator system.

- A secondary concentrating system with the possibility of balancing in the North-South direction pivoting with respect to a secondary axis in the East-West direction, which comprises an absorber tube or tubes which / is / contains a heat transfer fluid. The fluid collects the energy projected by the mirrors and transports it.

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- Controlled motor means and transmission means that transmit the movement of the controlled motor means and pivot the secondary concentrator system, the mobile structural system and the mirrors, providing the Fresnel linear solar concentrator with triple movement.

In a preferred embodiment, the movement of the secondary concentrator system with respect to the mobile structural system is in the same direction and at the same angular velocity, keeping both systems in parallel. In this way an optimization of the absorption of solar energy by the absorber tube or tubes is achieved by eliminating the losses of the end of the tube.

In another preferred embodiment, the mirrors are flat. In another preferred embodiment, the mirrors are curved, preferably with the focus arranged on the secondary concentrator system.

In another preferred embodiment, the heat transfer fluid is water.

In a specific embodiment, the controlled motor means comprise:

- electric motors, associated with each pivot axis;

- an electric or electronic speed and / or angular position control of each electric motor.

In another specific embodiment, the transmission means comprise an axle and two bearing and bearing carrier assemblies, associated with each pivot axis.

With the use of the three-movement CLF, it is possible to maximize the absorption of solar energy by the secondary concentrator system, reduce the surface area necessary for its installation, reduce the separation between several CLFs in their joint installation and optimize their application to heating or heating. refrigeration since it allows to obtain more energy in the winter months than in the summer months, or vice versa.

The concentrator of the invention allows solar tracking over time in an optimized manner and can also concentrate solar radiation more efficiently thanks to the possibility of having a triple movement. This makes it possible to manufacture very effective equipment, but at the same time very compact. In addition, thanks to its flexibility of movements, the area necessary for its installation is reduced, which is another important parameter in applications such as building, where the available space is usually limited to the building floor.

In one of the embodiments of the invention, balancing is proposed in the North-South direction, both of the mobile structural system and of the secondary concentrator system, so that all the rays reflected in the North-South direction impact on the absorber tube, regardless of the time of day and day of the year canceling the end of tube losses.

The invention results from application in those sectors in which equipment for the generation of thermal energy from radiation is manufactured or used, such as the case of the building sector, where domestic hot water, heating and / or water is needed. cooling and electric energy simultaneously.

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Due to its high efficiency, it also results from application in water purification and water desalination.

Description of the figures

Fig. 1 shows a side view of the CLF with triple movement. This figure shows the fixed structural system (1), the mobile structural system (2) and the secondary concentrator (3). The mobile structural system (2) supports a primary concentrator system (4) not shown in this figure since it is hidden, with the mirrors (5) not rotated, behind the mobile structural system (2). The figure also shows transmission means (7) between the fixed structural system (1) and the mobile structural system (2) that serve so that the mobile structural system (2) can balance in the North-South direction pivoting with respect to a primary axis (y) (represented in this figure by a point) in the East-West direction. Also shown in the figure are other transmission means (7) between the fixed structural system (1) and the secondary concentrator system (3) that serve so that the secondary concentrator system (3) can balance in the North-South direction by pivoting with respect to a secondary axis (x) (represented in this figure by a point) in the East-West direction. Associated with the two previous axes are also shown controlled motor means (8). In the figure you can also see the direction of the reflector axis (z) by means of a dashed and dotted line. In the lower part, the North-South cardinal direction is indicated by an arrow with the letters N and S at its ends and perpendicular to it, in the form of a point with an E inside, the direction

Fig. 2 shows a front view of the triple movement CLF of the previous figure. This figure shows the fixed structural system (1), the secondary concentrator system (3), transmission means (7) between the fixed structural system (1) and the secondary concentrator system (3), the concentrator system primary (4), the rows of mirrors (5) of the primary concentrator system (4) and transmission means (7) that allow the rows of mirrors (5) to balance in an East-West direction pivoting with respect to a reflector axis ( z) North-South direction. In the lower part, the East-West cardinal direction is indicated by an arrow with the letters E and O at its ends and perpendicular to it, in the form of a point with an N inside, the North-South direction.

Fig. 3 shows the primary concentrator system (4). In this figure you can see the rows of mirrors (5) of the primary concentrator system (4), transmission means

(7) that allow the rows of mirrors (5) to balance in the East-West direction by pivoting with respect to a reflector axis (z) in the North-South direction and controlled motor means

(8). In the lower part, the east-west and north-south cardinal directions are indicated.

Fig. 4 shows the inside of a secondary concentrator system (3). In this figure you can see an absorber tube (9), a specular surface (10) reflecting the radiation reflected in the mirrors (5), an insulation (11), a transparent bottom cover (12) and controlled motor means ( 8).

Explanation of a preferred embodiment

For a better understanding of the present invention, the following example of preferred embodiment is described, described in detail, which should be understood without limiting the scope of the invention.

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The fixed structural system (1) was constructed with a square tube of carbon steel, whose mission is to support the mobile structural system (2) and the secondary concentrator system (3). This fixed structural system (1) consisted of two bases, one lower and one upper. On the lower base, transmission means (7) were placed, which serve so that the mobile structural system (2) can balance in the North-South direction pivoting with respect to a primary axis (and) in the East-West direction. The rotation motion energy in the North-South direction of the mobile structural system (2) was provided by controlled motor means (8) consisting of an electric motor and an electronic angular position control. Transmission means (7) were placed on the upper base. These transmission means serve so that the secondary concentrator system (3) can balance in the North-South direction pivoting with respect to a primary axis (x) oriented in the East-West direction. These transmission means (7) were materialized by means of a shaft and two bearing and bearing carrier assemblies, associated with each pivot shaft. The rotational motion energy in the North-South direction was provided by other controlled motor means (8) similar to the previous ones.

The mobile structural system (2) supports the primary concentrator system (4). The primary concentrator system (4) was made up of rows of mirrors (5). It was also provided with transmission means (7) that allow each of the rows of mirrors (5) to balance in the East-West direction pivoting with respect to a reflector axis (z) in the North-South direction, and they were also arranged controlled motor means (8) consisting of another electric motor and an electronic angular position control to obtain this rotational movement.

The secondary concentrator system (3) consists of an absorber tube (9), a reflective specular surface (10), an insulation (11), a transparent bottom cover (12), and motor means (8) like the previous ones. The specular reflecting surface (10) was given the appropriate shape to concentrate on the absorber tube or tubes (9) the reflected rays of the primary concentrator system (4) that do not directly impinge on the absorber tube or tubes (9). It was made of polished stainless steel sheet. The insulation (11) was constructed of glass wool and serves to prevent the transmission of heat by conduction of the absorber tube (9) towards the surrounding environment. The lower cover (12) was made of tempered glass and serves to prevent cooling of the absorber tube (9) due to air currents that could affect the secondary concentrating system (3). The absorber tube (9) was made of carbon steel tube and serves to circulate a heat transfer fluid inside. The heat transfer fluid was sanitary quality drinking water obtained from the water supply network. This fluid is heated due to the direct solar irradiance that hits this tube. The absorber tube (9) was painted matt black with a special high temperature resistant paint.

Claims (7)

5 10 fifteen twenty 25 30 35 40 Four. Five 1. Fresnel linear solar concentrator comprising: - a fixed structural system (1) anchored that supports a secondary concentrator system (3) which balances in the North-South direction pivoting respect to a secondary axis (x) oriented in the East-West direction, and also serves of support for a mobile structural system (2) that balances in the North-South direction pivoting with respect to a primary axis (and) in the East-West direction; - a mobile structural system (2) that supports a primary concentrator system (4); - a primary concentrator system (4) which in turn comprises one or more mirrors (5) arranged in one or several rows, where each of the mirrors (5) swings in an East-West direction pivoting with respect to a reflector axis (z ) in the North-South direction and where each of the mirrors (5) reflects the solar radiation on the secondary concentrator system (3); - a secondary concentrator system (3), which in turn contains a heat transfer fluid that circulates inside the tube or absorber tubes (9), which collects the energy projected by the mirrors (5) and transports it; - controlled motor means (8) and transmission means (7) that transmit the movement of the controlled motor means (8) and pivot the secondary concentrator system (3), the mobile structural system (2) and the mirrors (5 ), providing the triple-movement solar concentrator. 2. Solar concentrator according to claim 1 characterized in that the movement of the secondary concentrator system (3) with respect to the mobile structural system (2) is in the same direction and at the same angular velocity keeping both systems in parallel. 3. Solar concentrator according to claim 1 characterized in that the mirrors (5) are flat. 4. Solar concentrator according to claim 1 characterized in that the mirrors (5) are curved. 5. Solar concentrator according to claim 1 characterized in that the heat transfer fluid is water. 6. Solar concentrator according to claim 1 characterized in that the controlled motor means (8) comprise: - electric motors, associated with each pivot axis; - an electric or electronic speed and / or angular position control of each electric motor. 7. Solar concentrator according to claim 1 characterized in that the transmission means (7) comprise an axis and two bearing and bearing carrier assemblies, associated with each pivot axis.