KR20220024542A - Hybrid radiation absorbers for solar power plants and methods of making such absorbers - Google Patents

Abstract

The present invention relates to a solar radiation absorber for a concentrating solar power plant, wherein the absorber is formed from a silicon carbide monolith, the surface of the absorber is coated, for example, with tungsten dendrite, in particular for the production of systems or collectors for solar power plants is for The present invention also relates to a method for producing such an absorbent body.

Description

Hybrid radiation absorbers for solar power plants and methods of making such absorbers

The present invention relates to the field of energy absorbers having properties similar to the behavior of a black body.

A black body is an ideal object that perfectly absorbs all electromagnetic energy it receives, without reflection or transmission. Under the influence of thermal agitation, a blackbody emits electromagnetic waves. In thermal equilibrium, emission and absorption are balanced and the radiation actually emitted depends only on temperature (thermal radiation).

Typical, non-limiting applications: gaseous fluids are possible for Stirling/Ericsson type external combustion engines, hot air turbines (turbo alternators), industrial processes, cooking, etc., liquid fluids are water to be heated, liquid to be sterilized, standard turbo alternator, DHW (domestic hot water/heating; domestic hot water/heating), steam production for various fluids, etc.

A new device that combines a concentrator and a Stirling engine is currently being developed to generate an electric current. However, the thermodynamic efficiency is correlated with the input temperature, and for best efficiency the temperature must be high enough. Existing devices are limited to 650/800°C, so 40% efficiency cannot be exceeded. The present invention makes it possible to reach 1200° C. and thus to reach and exceed a net efficiency of 60%.

prior art

There are various technologies for collecting solar radiation, transporting and storing heat, and converting heat into electricity. In any case, one of the essential elements of a concentrating solar power plant is a solar radiation absorber that forms part of the receiver. In order to maximize the efficiency of the absorber, coatings these days commonly referred to as selective coatings or selective treatments are included. The selective coating is intended to absorb as much incident solar energy as possible while re-emitting as little infrared light as possible (blackbody principle). In particular, this selective coating is considered perfect if it absorbs all wavelengths less than the cutoff wavelength and reflects all wavelengths greater than this same cutoff wavelength. The optimal cutoff wavelength depends on the operating temperature of the absorber element being considered and is typically between 1.5 pm and 2.5 pm. The optimal cutoff wavelength is, for example, 1.8 pm when the temperature is on the order of 650 K.

Patent application US2015033740 describes a solar receiver comprising:

* Includes a low pressure fluid chamber operating at up to 2 atmospheres pressure, fluid inlet, fluid outlet and openings to receive concentrated solar radiation.

* Solar absorber housed in a low pressure fluid chamber; and

* a plurality of transparent objects having divided walls of the low pressure fluid chamber;

* Concentrated solar radiation received through the opening passes through the partitioned walls and between the transparent objects into the low pressure fluid chamber and impinges on the solar absorber.

Patent application US4047517 includes a plurality of elongated vane structures arranged in a converging configuration from an outer portion to an inner throat portion, wherein the outer intermediate surface of the vane is at least partially reflective surfaces and the intermediate to inner surface of the vane selected at a small angle of incidence Radiant energy impinging at least one portion of the surface that absorbs the radiant energy impinging on the surface, or the outer part of the vane by reflecting the radiant energy impinging at a greater angle of incidence, is reflected towards the throat of the vane and radiant energy of the inner part is impinging on the selection surface at a relatively small angle, and the movement of radiant energy relative to the vane while impinging the selection surface at a relatively large angle of incidence is reflected into the throat of the vane to create an elevated temperature adjacent the throat of the vane. Describes a radiant energy receiver that indicates that an initial or actual reversal of direction has been absorbed.

Disadvantages of prior art

The performance of the state-of-the-art problem-solving principles is limited by the energy conversion capacity of the absorber, which limits the efficiency.

In addition, known absorbers are exposed to ambient air which results in significant heat losses. Known absorbers have a smooth, low absorptive and high emissive heat collecting surface. Known absorber materials cannot be used at high temperatures and cannot withstand excessive pressure or stress.

The present invention is particularly ideal for solar radiation produced from solar radiation by solar power plants, which is 30% more efficient than solar power, but is more suitable for the production of bulky and large-capacity electricity, either by HHO or by flames of the renewable flame solar method. It relates to the field of absorbers intended for energy.

In order to solve this drawback, the present invention is characterized in that it is formed from a monolithic piece of silicon carbide in the most general sense, the surface of which is absorbing, for example, coated with tungsten dendrite (or other substrate). It relates to solar radiation absorbers for power plants. The present invention also relates to a collector for a concentrating solar power plant, formed by a cavity, for example a graphite cavity, having a transparent entrance window arranged with an absorber according to the invention, the surface of which is ideally Coated with tungsten (or other) dendrite, characterized in that it is formed from a monolithic piece of silicon carbide.

Advantageously, the collector comprises a burner arranged in said cavity, which directs the flame in the direction of the absorber.

According to one variant, the collector consists of an optical fiber that transmits solar energy to the absorber.

Advantageously, at least part of the inner surface of the cavity has a cavity that behaves like a light trap (conical honeycomb).

The present invention also relates to a system comprising a collector for a concentrating solar power plant thermally and mechanically coupled to the inlet of a thermal machine, said collector by means of a graphite cavity with a transparent inlet window disposed with an absorber formed as a monolith of silicon carbide. formed, and its absorption surface is coated with tungsten dendrite.

Advantageously, said expansion machine has an upper part made of silicon carbide.

The present invention also relates to a method for manufacturing an absorber according to the present invention, wherein the manufacturing method comprises, for example, a thin layer absorbing radiation which may consist of a plasma spray on the surface of a silicon carbide monolith or a concentrated solar flux of tungsten dendrites. It characterized in that it comprises the step of depositing. Said layer can also advantageously be deposited as soon as it emerges from the moulding, and the paste obtained is relatively cohesive, allowing easy fixation of the dendrites by simple mechanical spraying or powdering.

According to one variant, this method comprises the step of laser projection of tungsten dendrites onto the surface of a monolith made of silicon carbide.

According to another variant, the present invention relates to:

Characterized in that the surface of the absorber is formed by an isolated cavity under vacuum, for example a graphite cavity, disposed in an absorber formed by a monolith of pure silicon carbide, coated by tungsten dendrite, with a transparent entrance window. Collectors for concentrating solar power plants.

Advantageously, the solar radiation absorber for a concentrating solar power plant comprises:

- Honeycomb configuration, the cells of the absorber are conical/trumpet-shaped with a greater height in the center and represent microcavities.

- Sealed spherical top/bottom support interface that serves as an assembly/sealing flange with supports with honeycomb and pin and threaded connections to the thermodynamic device.

- Fins with a higher height microcavity in the center and heat exchange with a rosette-shaped fluid

- Sealing discs and fluid passage ports.

- Central spiral truncated section with 90° return and trumpet/conical shape.

- A burner disposed inside the cavity to guide the flame in the direction of the absorber.

- Exchange the surface with microcavities.

- The present invention also relates to a system comprising a collector for the aforementioned concentrating solar power plant thermally and mechanically coupled to a tubing (hot fluid outlet) or an inlet of a thermal machine, said collector comprising a monolithic piece of silicon carbide The formed absorber is formed by a graphite cavity with a transparent entrance window disposed therein, the surface of which is coated with tungsten dendrite.

Preferably, the expansion machine has an upper part made of silicon carbide.

Advantageously, it is produced in a plasma spraying step of coating tungsten dendrite on the surface of a monolithic piece made of silicon carbide and/or in a pasty phase of tungsten dendrite on the surface of a monolithic silicon carbide piece. It includes a deposition step by pulverization while forming.

The absorber according to the present invention allows for the hybridization of other heat sources, such as for example solar and "solar fuel" = HHO (or biogas, petroleum derivatives, etc.), and thus at full power despite fluctuations or absence of solar fluxes. Enables continuous operation of the equipment.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood by reading the detailed description of the non-limiting embodiments of the present invention set forth below with reference to the accompanying drawings.
- Figure 1 shows the pin, absorber body of the fluid exchanger at the top, the sealed interface in the center (3) and the bottom towards the top (sun/fire) comprising a honeycomb.
- Figure 2 shows a bottom view of the exchanger with a helical cone in the center;
- Figure 3 shows only the interface part and the lower part.
- Figure 4 shows a honeycomb.
- Figure 4a shows a dendrite.
- Figure 5 is a simplified representation of the honeycomb matrix.
6 shows a first form of tungsten dendrite.
- Figure 6a shows another form of tungsten dendrite.
7 shows a close - up of a dendrite fused to a CSi support.
Figure 8 shows the external containment enclosure (unit for solar concentrators).
9 shows a detailed cross-section of a helical cone;
- Figure 10 shows a 3D representation of a helical cone for the understanding of the device.

DETAILED DESCRIPTION OF THE NON-LIMITING EMBODIMENTS OF THE INVENTION

Description of the use situation of the absorber according to the present invention

A heat collector absorbs solar radiation and converts it into heat. This heat is transferred to the heat transfer fluid. The collector consists of an absorber, heat transfer fluid, insulation, sometimes glazing and reflector.

The absorber is one of the most important parts of the collector. The absorber converts solar radiation into heat.

The absorber has two parameters.

- solar absorption coefficient a* (or absorbance): the fraction of the light radiation absorbed by the incident light radiation;

- Infrared emission coefficient e (or irradiance): the ratio between the energy radiated in infrared light when the absorber is hot and the energy radiated by a black body at the same temperature.

In the field of solar heating, the goal is to obtain the best solar absorption coefficient/infrared emission coefficient ratio. This ratio is called selectivity.

The material of the absorber is usually made of copper or aluminum, but sometimes it is also made of plastic. Properties of some materials used as absorbers.

The structure of the absorber is exemplarily described in FIGS. 1, 2, 3 and 8 .

The absorber comprises a honeycomb structure 1 exposed to solar radiation through a window 10 . The absorber is secured to the enclosure with a flange (2). The membrane 3 forms a sealed interface. The seal 4 ensures tightness between the flange 2 and the inner shoulder of the enclosure. Structures 6 , 12 have a central spiral truncated cross-section with a lower fin 5 . The absorber is fixed with screws (7).

A sealing disk 11 extends below the structure 12 .

In the region between the window 10 and the honeycomb structure 1 , the burner injects hot gas.

This area has outlets 14 .

The honeycomb structure accommodates heat flow, has a sealed interface in the center, has flanges with fins over the entire height on the sides (which can withstand high pressure), and a spiral cone below the center (directs the fluid at 90°). reversible), at the bottom of the sealing disk = fluid circuit is sealed and allows circulation from the periphery to the center and vice versa (reversible/alternatively).

matter absorption rate emissivity selectivity maximum temperature α* ε α* / ε nickel 0.88 - 0.98 0.03-0.25 3.7 - 32 300°C graphite film 0.876 - 0.92 0.025-0.061 14.4 - 36.8 250°C black copper 0.97 - 0.98 0.02 48.5 - 49 250°C black chrome 0.95 - 0.97 0.09-0.30 3.2 - 10.8 350-425°C

Therefore, in order to achieve better efficiency, certain systems are constructed with certain coatings.

The heat transfer fluid can dissipate the heat stored in the absorber and transfer it to where it will be consumed.

A good heat transfer fluid should consider the following conditions:

- It is chemically stable when reaching high temperatures, especially when the collector is stagnant.

- It should have anti-freezing properties related to local weather conditions.

- It has anti-corrosive properties depending on the properties of the material present in the collector circuit.

- In order to transport heat efficiently, it must have high specific heat and thermal conductivity.

- Non-toxic and low environmental impact.

- It should have a low viscosity to facilitate the operation of the circulation pump.

- It should be readily available and inexpensive.

A reasonable compromise to this criterion is a mixture of water and glycol (used in automotive coolants), but it is not difficult to find systems that operate on pure water or simply air, depending on the application.

Glazing protects the inside of the collector from environmental influences and improves the efficiency of the system by the greenhouse effect.

- When effective glazing is required, it must have the following characteristics:

- Minimally reflects light radiation regardless of its inclination.

- Absorbs minimal light.

- It has excellent thermal insulation properties by maximizing infrared radiation.

- Over time, withstanding environmental influences (rain, hail, insolation, etc.) and large temperature changes.

The main glazing used in collectors is based on iron-free or acrylic glass, often with an anti-reflective coating.

Insulation limits heat loss, and its properties include conductivity; The lower the conductivity, the better the heat insulation.

The main materials used in the collector are rock and glass wool, polyurethane foam or melamine resin.

Some insulators used in heat collectors:

matter thermal conductivity rock wool 0.032 - 0.040　W/m.K glass wool 0.030 - 0.040　W/m.K Polyurethane (waterproof) 0.022 - 0.030　W/m.K

In the case of glazed collectors, it is also interesting to replace the insulation between the glass and the absorber with air. In fact, air is used for double-glazed windows because of its excellent thermal insulation properties. To still achieve better efficiencies, some manufacturers use other gases, such as argon or xenon, preferably vacuum, if possible. The insulation coefficient of the gas used as an insulator is as follows.

gas Thermal Conductivity at 283 K, 1 K bar air 0.0253　W/m.K argon 0.01684　W/m.K xenon 0.00540 W/m.K

Description of the absorber according to the present invention

The absorber according to the present invention consists of a monolith of CSi deposited during manufacture on a paste or projected by a laser or plasma, tungsten dendrite, a crystalline form that absorbs 98% of infrared radiation, which has a melting point of 3,400 °C or higher. .

For the purposes of this patent, the term "dendrite" is understood to mean a crystalline form obtained by solidification and having an arborescent shape. For example, snowflakes have a dendrite-like structure. The dendrites are preferably industrial residues or dust or are produced by the solar route at high temperatures.

The agglomeration of tungsten dendrites on CSi can be carried out in a thin layer under high temperature conditions or by other methods.

Therefore, the absorber forms a light trap by using a microcavity created during molding, in particular, in order to have properties close to that of a black body.

DETAILED DESCRIPTION OF THE INVENTION

The main characteristics of the absorber are as follows.

a) receive and transmit as much energy as possible;

b) It is a very good heat conductor.

c) Does not reflect or radiate IR (infrared rays).

d) provides a very high energy density.

e) Withstand thermal shock and remain chemically inert.

f) does not deteriorate over time;

g) It has the lowest possible manufacturing cost.

h) prone to industrialization.

i) It has significant mechanical properties.

The first characteristic of an absorber is its ability to receive radiation (sun/fire) and transmit the radiation into a fluid with the highest possible efficiency.

The absorber is in a vacuum chamber that allows for complete insulation. This insulation is ideally covered with a window made of graphite and covered with an anti-reflective coating that is transparent to solar radiation and limits optical losses. The vacuum cavity is equipped with a burner that can supply the required energy in the absence of solar flux and is equipped with an vent for evacuating combustion residues.

Most of the known absorbers use materials such as stainless steel, with or without an absorbent/selective coating. These materials have very limited absorption and re-diffuse a significant portion of infrared radiation. Also, the conductivity is very limited at about 20 W/mK, which is an important property for the quality of the absorber, which is very poor compared to other known materials, such as copper = 386 W/m.k, which has proven to be 20 times better as a heat conductor. Stainless steel can only be used up to 800°C, which limits its beneficial thermodynamic efficiency in the high temperature range. One suitable material provided herein and one suitable material to be recited herein is silicon carbide (CSi) in relatively pure form.

Pure CSi is an excellent conductor of heat up to 1200°C, providing excellent properties close to copper with a maximum conductivity of 350 W/m.k; It also conducts IR (infrared) perfectly. Pure CSi also withstands significant thermal shock, and the very high hardness and mechanical strength of pure CSi allows parts to be designed to withstand very high stresses, resulting in thin parts with good thermal conductivity. Pure CSi is chemically inert, withstands very high temperatures and does not degrade over time.

In contrast, pure CSi, similar to glass, is usually transparent to solar radiation and therefore does not absorb the concentrated solar flux and is damaged by several problems.

Moreover, it is very difficult to produce parts with the complex shapes required to produce near-perfect absorbers. Finally, the realization of a perfect absorber requires a large amount of energy and very high temperature.

To solve this, the absorber according to the present invention has a surface exposed to a heat source covered with a thin layer of tungsten dendrite. Tungsten dendrites have the property of perfectly capturing solar radiation or radiation from the flame and transferring it to the supporting substrate with an efficiency of 98%. To this end, the dendrites are deposited by means such as, for example, by a plasma torch or other suitable method, and the tacky paste viscosity allows perfect cohesion, especially when the CSi is released during the molding process.

In order to absorb the incident flux as efficiently as possible, it is necessary to capture the incident radiation and create a specific shape capable of capturing it. Known absorbers generally have smooth surfaces and reflect a large portion of the radiation. The present invention acts as a light trap and has a geometric shape compared to a black body. To this end, the surface is conical and consists of a honeycomb structure with a thin top and a wide bottom.

Thus, the incoming radiation cannot escape and can be captured with the greatest possible efficiency as it is perfectly captured by the dendrites and transfers the flux to the CSi substrate.

The present invention makes it possible to solve this problem due to two innovative methods. One is high pressure isostatic pressure, and the other is additive manufacturing by 3D printer. The high pressure isostatic pressure developed by the present inventor makes it possible to send the CSi paste into a mold formed of two or more parts, almost similar to plastic or metal injection, one for the upper part, the second for the lower part, and the third for the screw/unscrew It may be a central helical cone that may require a function or two independent molded half-shells. It is therefore possible to obtain parts with complex shapes with very thin thicknesses that can be on the order of millimeters, which is the geometry of the part that makes this type of production possible. The sealing disc can be added directly to obtain a monolithic part.

A second method we have successfully tested is additive printing or 3D printing. A nozzle or set of nozzles applies CSi paste to a plate to progressively form a shaped part, the complexities of which are nearly infinite or achieve a shape that would otherwise not be achievable.

The honeycomb-shaped surface ideally consists of a roughened surface with microcavities that favorably absorb light and allow easy attachment of dendrites. Likewise, the lower fins can have microcavities that create micro-turbulence, which on the one hand contributes to reducing the friction of the surface which increases the heat exchange coefficient and on the other hand increases the overall efficiency.

After various suitable treatments, the parts are conventionally sintered in a high-temperature furnace supplied with gas or electricity, but ideally via a highly concentrated solar route to significantly reduce production costs. The absence of a solar light source is ideally compensated for by the combustion of the HHO mixture, which produces a very high quality flame at 2800 °C, the only residue of combustion being water vapor which can be recycled indefinitely. HHO mixtures, also referred to as “solar fuels,” can ideally be produced via the solar route, thereby lowering energy costs. Another advantage of this solar method is that controlled annealing can be considered to release tension, which is very inexpensive.

Therefore, it can be expected to industrially produce parts with complex shapes at a very high speed and very low manufacturing cost while having a carbon index close to or equal to zero.

The absorber is monolithic, but for convenience of explanation, it is divided into three parts here. The first part is the upper part that receives the heat flow, and the second part is the interface that supports the two main parts and allows the assembly to be performed while ensuring rigidity in the structure under pressure. The third part is the bottom, which transfers thermal energy within the fluid. The assembly is not only concave in shape to optimize the capture and transmission of energy, but also ensures the highest mechanical strength by equalizing the energy flow and mechanical forces applied to the surface.

As described above, the upper part has a conical honeycomb structure that is open to the opposite side to make the temperature gradient uniform (FIG. 4), and the surface thereof is covered with a thin layer of tungsten dendrite. This cone is higher and wider at the center due to the fact that the solar flux or flame is always greater at the center, so that of the material requiring a higher density is transferred to the surrounding elements by conduction.

Due to the excellent properties of CSi and the implementation method according to the present invention, it is possible to manufacture a convection fin (honeycomb) having a thickness of the order of millimeters on the top. A "leading edge" (the jargon) that is exposed to direct sunlight or flames (hence the top) is rounded to avoid peeling and sharp edges that are very fragile.

Another advantage of the honeycomb structure is that it perfectly dissipates thermal and mechanical stresses. Because the height of the honeycomb is higher at the center than at the periphery, the thermal and mechanical stresses are uniformly distributed over the entire surface, so that the structure can be subjected to much greater pressure at the center, for example, having a smooth, spherical surface and a constant thickness. Like stainless steel, unlike known absorbers, it is able to withstand extreme energy and mechanical densities.

In the continuity of the honeycomb structure there is an "interface" (a sealed concave disk separating the lower and upper parts) that accommodates the upper and lower, two interchangeable parts. This interface ensures the continuity of the seal between the two opposing parts and an adequate energy transfer evenly distributed over the entire surface. Its shape is preferably spherical and the concave part faces upward (the part receiving the flow), which allows the absorber to withstand very high pressures with the thinnest possible thickness, which contributes to thermal efficiency. This small thickness can also limit the mechanical stress or known molecular defects at large thicknesses, as well as limit the quality of sintering, which is essential to ensure the durability and reliability of the absorber.

To ensure that the absorber is securely mounted between the various components of the thermal imaging device, the outer perimeter consists of a flange-like perimeter bearing surface that is assembled with an external device. It is thick enough for the stress to be applied and is designed to fit the slightly larger section of the cylinder where the absorber is located to ensure a rigid assembly.

To this end, one can envision a ring equivalent to a seal, produced around the center to apply pressure to a defined limited surface within an ideal flange, under very high pressure.

A seal created around the center to apply pressure to a limited surface defined inside the flange and this protruding ring can be replaced with a groove to accept a standard seal or a flat surface for a specific flat seal, especially of the metal type. . An insulating seal made of graphite, for example, can be considered an ideal way to withstand high temperatures. Another advantage of this type of gasket is that it forms a thermal bridge and prevents heat transfer to the external support.

In this case, the absorber is mounted directly on the external accommodating cylinder, as shown in FIG. 8, and in particular, given that the window of the cavity accommodating the absorber is ideally in a vacuum state, sufficient gas pressure is applied so that it can be mounted quickly and easily like a tubeless tire. all. This allows for self-adjustment and displacement of the absorber on the sealed surface, thereby avoiding the creation of mechanical stresses due to differences in expansion of the various components of the device.

The lower part of the "flange" allows for the mounting of additional components and devices, in this sense has a yaw that allows for mechanical coupling such as screws or suitable assembly systems, especially quarter turn type assembly which allows quick and economical assembly . The screw or assembly device may be positioned on either side to allow for a durable and secure mechanical assembly while allowing perfect maintenance of the pressure applied to the sealing device/seal.

The lower end of FIGS. 2 and 3 is composed of fine fins forming a rosette so that thermal energy can be transferred to the heat transfer fluid or working fluid/fluid to be heated. The pin is embedded in the "flange" part over its entire height to obtain a monolith that, in particular, withstands high pressure and distributes the force evenly.

The focused solar flux resembles a Gaussian curve, i.e. the maximum intensity at the center. As a result, the fluid ideally moves from the periphery to the center to avoid heat loss in the sealing flange.

To this end, “ports” (passages) are created all around the perimeter of the pin inlet to allow fluid to pass through.

This port is imposed by a sealing disk attached to the pin and locked in the same way with mounting lugs to prevent displacement or vibration.

The assembly may also advantageously be in monolithic form, depending on the method of manufacture, the latter avoiding the addition of mechanical fastening/retaining devices.

This arrangement (rosette), in which parts of the circle are superimposed inside another, makes it possible to create a certain number of turbulences and to guide the fluid in a very precise direction. In addition, the centripetal force increases the interaction of the fluid on the fin surface to improve the heat exchange coefficient. This unique arrangement can also increase the exchange surface and increase the thermal efficiency of the absorber. The spacing between the fins is larger at the periphery than at the center for a perfect correlation with the energy density embodied in the surface.

Moreover, the fins are higher at the center than at the periphery, on the one hand allowing heat exchange to be optimized, allowing the greatest energy density to be at the center and, on the other hand, in particular the very high pressures required for thermodynamic devices, e.g. Stirling types. Contributes to the mechanical strength of the assembly when receiving. This makes it possible to have very thin interfaces while ensuring extremely mechanical resistance to very high pressures.

Due to the specific shape of the fins, a rapid vortex is formed in the center of the substructure, which is redirected out of the absorber by a frusto-conical cross-section taking the direction of the initial flow in a vertical direction or towards the tubing, or, in the case of certain thermodynamic devices, towards the piston. . The frusto-conical section, on the one hand, directs the flow in a new vertical axis and on the other hand makes it possible to prevent overheating of the central region most exposed to incident thermal radiation due to the increased flow rate by the Venturi effect. Includes spiral pins. The center of the cone is relatively thick, while the tip is thinner. The lower base of the frustoconical section is advantageously curved to avoid excessive turbulence and pressure drop which impedes overall efficiency. This helical shape preferably approaches the sealing disk in one direction of the fluid, to avoid losses associated with leaks or guiding defects.

To ensure the tightness of the bottom, a sealing disc can be used to close the bottom, leading to perfect heating of the fluid. This disk contains a central opening connectable by an outer diameter slightly smaller than the diameter of the pin as well as a cylinder portion in the tubing, either to the piston or to the tubing, to allow passage of fluid from the periphery.

The attachment device with the body of the absorber is produced from a sealing disc, the latter being accomplished by constructing a monolithic assembly in the case of lamination printing or several methods such as lugs, notches or other assembly methods. Another advantageous method is that as soon as the body of the absorber comes out of the molding, the discs are assembled and glued and then easily assembled, even during production, by lamination printing.

In general, all sharp angles that impede the movement of fluids are rounded off to prevent turbulence and other harmful cloud pressure drops.

The lower part is also designed to reciprocate quickly without loss of head of fluid in the external and return directions, as is the case with the FPSE process (free piston Stirling engine, which can have a frequency of several tens of cycles per second).

Claims (12)

An absorber formed by a monolith of silicon carbide with a transparent inlet window and formed by an isolated cavity under vacuum, for example a graphite cavity, is disposed, the surface of the absorber of the absorber being coated with tungsten dendrite A collector for a condensed solar power plant.
The solar radiation absorber of claim 1 having a honeycomb structure, wherein the cells of the honeycomb structure provide microcavities in the form of cones/trumpets of greater height in the center.
2. For a concentrating solar power plant according to claim 1, characterized in that it has a sealed spherical top and bottom supporting an interface serving as an assembly and a support with a honeycomb structure and fins and threaded connections of pipes on the thermodynamic device. Solar radiation absorber.
The solar radiation absorber for a concentrated solar power plant according to claim 1, characterized in that it has rosette-shaped fins for heat exchange with a fluid and has a higher microcavity in the center.
The solar radiation absorber of claim 1 having a sealing disk and a fluid passage port.
The collector of claim 1 , characterized in that it has a central spiral truncated cross-section with a 90° return and flare and conical shape.
The collector of claim 1 , comprising a burner disposed inside the cavity and directing a flame in the direction of the absorber.
The collector of claim 1 comprising an exchange surface with microcavities.
2. A graphite cavity according to claim 1, wherein the collector is thermally and mechanically coupled to a tubing (hot fluid outlet) or an inlet of a thermal imaging machine, the collector having a transparent inlet window disposed with an absorber formed in a monolith of silicon carbide and , A system consisting of a collector for a concentrating solar power plant, characterized in that the surface of the absorber of the collector is coated with tungsten dendrite.
10 . The system according to claim 1 , characterized by an expansion machine with a top made of silicon carbide.
The method of claim 1, comprising a plasma spraying step of coating a surface of the monolithic part made of silicon carbide with tungsten dendrite.
11. Method according to claim 1, characterized in that it comprises the step of depositing by pulverization during production in the pasty phase of tungsten dendrite on the surface of the silicon carbide monolith. .

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