ITUB20150481A1 - Method and system for the generation of steam in a planar structure by solar radiation or other radiation - Google Patents

Description

? Method and system for the generation of steam in a planar structure by solar radiation or other radiation?

DESCRIPTION

TECHNICAL FIELD

The present invention relates to the energy sector and, specifically, to the generation of steam.

Pi? precisely, the present invention relates to a method, and the relative system, for the generation of steam in a planar structure by means of solar radiation or other radiation.

Even more? precisely, the present invention relates to a method, and the relative system, for the generation of steam in a planar structure by means of solar radiation or other radiation, in which the fluid which is made to evaporate? in the form of a thin film.

The present invention finds a preferred and advantageous application when used for the generation of steam and its subsequent condensation in sea, river, marsh or rainwater purification and / or desalination plants; the present invention is particularly suitable for use in remote regions and for so-called "off-grid" applications.

STATE OF THE ART

Solar steam generators or evaporators are known generally formed by a closed container equipped with a transparent cover capable of letting the solar radiation pass and, at the same time, guaranteeing a cold surface for condensation; examples of such solar evaporators, in their various variants, are described in the scientific publication V. Sivakumar, E.Ganapathy Sundaram,? Improvement techniques of solar still efficiency: A review ?, Renewable and Sustainable Energy Reviews 28, pp. 246? 264, 2013.

In particular, evaporation takes place through a free surface or a porous matrix, in contact with humid air trapped inside the evaporator and subject to natural convection.

Such a configuration has some intrinsic limits: (a) the radiation must pass through a transparent medium, which absorbs a not negligible amount of solar radiation, dispersed in the environment; (b) traditional devices are subject to losses due to convective motions external to the evaporator; (c) in traditional evaporators, the ratio between the surface subject to solar radiation and the volume of water contained in the evaporation chamber? rather low; (d) vice versa, the ratio between the dispersing surface towards the environment and the same volume of water in the chamber? quite high, resulting in low energy efficiency.

Steam generation methods and systems are also known which exploit solar radiation or other radiations; examples of such methods and systems can be found in the International application published under no. WO 2004/035168 A2, in US Patent Application No. US 2008/0164135 A1 and in the International application published under no. WO 2014/172859 A1.

The International application published under n. WO 2004/035168 A2 describes a method for the desalination of water by means of solar energy and, in particular, among the various solutions proposed, provides for the handling of a thin film of salt water placed on a belt conveyor.

The solution described in this document, while addressing the technical problem of generating steam using solar radiation, does not? however it is able to guarantee the optimal thickness of the thin film that is lying on the belt conveyor and to control the flow rate of fluid inside the thin film, independently from the speed? belt sliding; also, the conveyor belt? subject to optical wear, since, in addition to performing the function of absorber of solar radiation, it must also guarantee mechanical handling; also, the handling of the fluid? entrusted entirely to the drive of the belt conveyor and can not? make use of other phenomena, such as capillarity? in the thin cavities; finally, for carrying out the described method, movement members and / or actuators are necessarily required.

The aforementioned International application published under no. WO 2004/035168 A2 also shows the use of a planar structure to generate steam by exploiting solar radiation or other radiations; however, said planar structure does not allow to produce thin films confined between two parallel flat surfaces, being substantially a mobile belt, moved by two rollers, on which a thin layer of salt water is deposited. In this document, therefore, the thin film, and in particular its thickness, is uncontrollable beyond certain flow rates, ie when the deposited drops are subject to coalescence.

The US patent application n. US 2008/0164135 A1 and, likewise, the International application published under no. WO 2014/172859 A1 describe generic paraboloid concentration systems for the treatment of water; however, these solutions do not enter into the merits of the reduction of losses by the receiver, nor? of its thermodynamic efficiency for the purpose of steam production.

Are also known methods and systems for the generation of steam in which the fluid that is evaporated? in the form of a thin film; an example of such methods and systems is found in Canadian Patent n. CA 2 347 456 C which describes the realization of the evaporation process in thin film through the use of cloths, fabrics or similar hydrophilic materials. However, the aforementioned technical solution necessarily requires the use of materials with non-repeatable and not well controllable performances, since? they are based on a substantially disordered microscopic structure. Furthermore, these are materials subject to wear and degradation over time as a result of continuous operation. Finally, also in this case, the flow rate of evaporating fluid? strictly linked to the speed? handling of the canvas.

Therefore, the need to generate steam by means of solar receivers for concentrating systems, capable of maximizing the flow of evaporating fluid and therefore the exploitation of solar energy, remains unsatisfied.

Furthermore, the need to effectively contain thermal losses towards the environment and to reduce optical losses remains unsatisfied.

In summary, up to the present moment, to the knowledge of the Applicant, there are no known solutions that allow to realize thin film evaporation, exploiting the best optical materials available today, for the reflection of the radiation and for the selective absorption / emission of the solar radiation in the range of the spectrum of interest for thermal applications, while avoiding optical transmission and reducing thermal losses towards the environment; therefore the Applicant, with the method and the system according to the present invention, intends to remedy this shortcoming.

AIMS AND SUMMARY OF THE INVENTION

? object of the present invention to overcome the drawbacks of the known art linked to the generation of steam by solar radiation or other radiation.

? It is also an object of the present invention to overcome the drawbacks of the known art linked to the generation of vapor from a fluid in the form of a thin film.

Pi? precisely, the present invention intends to solve the problem of thin-film evaporation by solar radiation or other radiation, exploiting the best optical materials available today, for reflection and selective absorption / emission of solar radiation, while avoiding optical transmission and minimizing thermal losses towards the environment.

In particular, the purpose of the present invention? that of providing a method for the generation of steam by solar radiation or other radiation in a planar structure inside which the fluid that is evaporated flows in the form of a thin film, possibly exploiting the phenomenon of capillarity. Furthermore, what is the purpose of the present invention? that of providing a system for the generation of steam by solar radiation or other radiation comprising a planar structure inside which the fluid that is evaporated flows in the form of a thin film, possibly exploiting the phenomenon of capillarity. The aforesaid and other objects and advantages of the invention, which will emerge from the following description, are achieved with a method for the generation of steam in planar structure by means of solar radiation or other radiation such as that according to claim 1.

Furthermore, the above and other objects and advantages of the invention are achieved with a system for the generation of steam in planar structure by means of solar radiation or other radiation such as that according to claim 8.

Preferred embodiments and variants of the method and system of the present invention are the subject of the dependent claims; in particular, in a preferred and advantageous embodiment, the method and the system according to the invention provide for the combination with a device suitable for condensing the steam produced, the condensate obtained being collected and subsequently used. In a further embodiment, the method and the system according to the present invention are used in plants for the purification and / or desalination of sea, river, marsh or rainwater.

It is understood that all the appended claims form an integral part of the present description and that each of the technical characteristics claimed therein? possibly independent and usable independently with respect to the other aspects of the invention.

Result? It is immediately evident that innumerable modifications can be made to what has been described (for example relating to shape, dimensions, arrangements and parts with equivalent functionality) without departing from the scope of protection of the invention as claimed in the attached claims.

Advantageously, the technical solution according to the present invention which realizes the generation of steam in a planar structure, allows:

- use in remote or so-called? off-grid? thanks to the fact that it does not require electricity;

- the use of a thin planar structure, per unit? of volume of water in the evaporation chamber, greatly reduces the dispersing surface through which the thermal flows towards the environment pass;

- the use of a thin planar structure, per unit? of volume of water in the evaporation chamber, maximizes the surface subject to solar radiation;

- in the inverted configuration (ie with direct radiation from the bottom upwards), it allows to effectively hinder, through the use of suitable septa, the external convective motions;

- the inverted configuration, then, lends itself well to the use of reflecting solar concentrators, with efficiencies typically higher than those with transmission; And

- does not require the use of transparent materials, consequently increasing the optical efficiency.

Further advantageous characteristics will become more evident from the following description of preferred but not exclusive embodiments, provided purely by way of non-limiting example.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will come described hereinafter by means of some preferred embodiments, provided by way of non-limiting example, with reference to the attached drawings. These drawings illustrate different aspects and examples of the present invention and, where appropriate, similar structures, components, materials and / or elements in different figures are indicated by similar reference numerals.

FIG. L ? a flow chart showing the steps of the method for generating steam in planar structure by solar radiation or other radiation according to the present invention; And

FIG. 2 ? schematic representation of a general embodiment of the system for generating steam in planar structure by solar radiation or other radiation according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

While the invention? susceptible of various modifications and alternative constructions, some preferred embodiments are shown in the drawings and will be described in detail below.

It must be understood, however, that there? no intention of limiting the invention to the specific embodiment illustrated, but, on the contrary, the invention intends to cover all modifications, alternative constructions, and equivalents that fall within the scope of the invention as defined in the claims.

In the following description, therefore, the use of? For example ?,? Etc.?,? Or ?,? Or? indicates non-exclusive alternatives without any limitation, unless otherwise indicated; the use of? also? means? including, but not limited to? unless otherwise indicated; the use of? include / includes? means? includes / includes, but not limited to? unless otherwise indicated.

The method and the system of the present invention are based on the innovative concept of using and converting radiant energy, with specific reference to solar energy.

An important feature of said method and system lies in the fact that they do not require electricity and, therefore, are particularly suitable - although certainly not limited - for remote or so-called? Off-grid? Applications.

In the present description, with the term? Solar radiation or other radiation? it is intended to indicate any electromagnetic radiation; pi? precisely, with the term? solar radiation or other radiation? it is intended to indicate the radiation received directly or indirectly from the Sun or from any other hot body, industrial device or thermal waste from an industrial process.

In the present description, with the term? Thin film? we intend to indicate a thin layer of fluid confined in the gap between two surfaces.

In the present description, with the term? Planar structure? we intend to indicate a pair of flat surfaces of any shape capable of creating a cavity in which to house a thin film of fluid, which completely invades the cavity itself and is possibly subject to the phenomenon of capillarity. One of the two flat surfaces? realized or? in good thermal contact with an optical material with properties? of absorption and selective emission of radiation, with the aim of maximizing the quantity? of energy absorbed by the structure itself. In this description the term? Planar cell? ? intended to have the same meaning as the term? planar structure? and ? used interchangeably to denote the same element.

With reference to Fig. 1, the method for generating vapor V in planar structure 100 by means of solar radiation or other radiation R according to the present invention comprises the steps of:

to. provide at least one planar structure 100 comprising:

? an upper element 1,

? a support 2,

? an interspace 3 between said upper element 1 and said support 2,

? a hole 5, e

? at least one duct 13,

where said hole 5? positioned on the face of said upper element 1 opposite said interspace 3 and in which the face of said support 2 opposite said interspace 3 comprises a material 4 absorbing solar radiation or other radiation R (step 101);

b. providing at least one reservoir 8 containing a fluid F (step 102);

c. providing at least one reflecting device 16 of solar radiation or other radiation R (step 103);

d. connecting said tank 8 containing said fluid F, by means of a connecting pipe 6, to said at least one planar structure 100 in correspondence with said hole 5 (step 104);

And. to make said fluid F flow in said interspace 3, so? making a thin film of said fluid F (step 105);

f. position said at least one planar structure 100 facing said at least one reflecting device 16 so that said face of said support 2, opposite said interspace 3 and comprising said material 4 absorbing solar radiation or other radiation R, faces and in correspondence with the the reflecting point (s) P of said at least one reflecting device 16 (step 106);

g. inducing the evaporation of said fluid F and the production of vapor V by releasing the thermal energy of said solar radiation or other radiation R on said planar structure 100, specifically on said face of said support 2 opposite to said interspace 3 and comprising said material 4 absorbing solar radiation or other radiation R (step 107); And

h. causing said vapor V to escape through said at least one duct 13 (step 108).

The method according to the present invention can? also include, optionally, the following steps:

the. providing at least one cold surface 15 (step 109);

j. directing said vapor V, released through said at least one duct 13, towards said at least one cold surface 15, on which condensation occurs (step 110); And

k. collect the condensate produced for subsequent use (step 111).

It is meant here to specify that said material 4 absorbing solar radiation or other radiation R? an absorbent material with high efficiency, with what? meaning a material capable of absorbing 95% of the incident solar energy and converting 90% into thermal energy, dispersing the difference in the form of radiation towards the environment.

Thanks to the use of said high-efficiency absorbent material, the planar structure 100 behaves as an almost ideal optical absorber, that is to say? with an absorption coefficient of 90% with respect to the incident radiation.

Said material 4 can? be used to cover the face of said support 2 opposite to said interspace 3; alternatively, said material 4 constitutes a coating layer of the face of said support 2 opposite to said interspace 3.

In case said material 4? used to cover the face of said support 2 opposite to said interspace 3, preferably it? a coating of suitable oxides able to guarantee the necessary properties? selective coating; pi? preferably? a layer of titanium dioxide; even more? preferably? a commercial titanium dioxide layer explicitly developed for solar applications, such as the TINOX material produced by the German company ALMECO GmbH.

Always in case said material 4? used to cover the face of said support 2 opposite to said interspace 3, it is preferably applied to said support 2 by physical vapor deposition (PVD, Physical Vapor Deposition).

Always in case said material 4? used to cover the face of said support 2 opposite to said interspace 3, preferably it has a variable thickness between less than 1 m and a few tens of? m, plus? preferably equal to 1-2? m.

If, on the other hand, said material 4 constitutes a coating layer of the face of said support 2 opposite to said interspace 3, preferably it? a sheet of coated metal; pi? preferably? a sheet of copper or aluminum coated; even more? preferably? a sheet of copper or aluminum coated with titanium dioxide, for example a sheet of TINOX material produced and marketed by the German company ALMECO GmbH.

Again in the case in which said material 4 constitutes a coating layer of the face of said support 2 opposite to said interspace 3, it preferably has a thickness varying between 0.1 mm and 2 mm, plus? preferably equal to 0.2 mm.

Always in the case in which said material 4 constitutes a coating layer of the face of said support 2 opposite to said interspace 3, it is preferably fixed on said support 2 by gluing, welding and localized fusion.

Preferably, said upper element 1? hydrophilic, so as to be able to distribute the fluid F in the interspace 3 by capillarity; pi? preferably? hydrophilic and low conductivity thermal (for example, not exceeding about 1 W / (m * K)); even more? preferably? glass.

We intend to specify here that he considers himself to be? Superior? the element of the planar structure 100 placed in connection with the tank 8 and opposite to the supporting element of the absorbent material 4.

Preferably, said support 2? made with sufficiently conductive materials from the thermal point of view (for example, with thermal conductivity of the order of 300 W / (m * K)); pi? preferably? made of metal.

It is intended here to specify that a first face of the support 2? in contact with the fluid F confined in the interspace 3, while a second face of the support 2? covered by or? in contact with the absorbent material 4.

Preferably, said interspace 3 has a variable dimension between 100 µm and 1,000 µm, preferably equal to 300 µm.

Preferably, said hole 5 has a variable diameter between 4 mm and 50 mm, preferably equal to 10 mm.

Since? the method according to the present invention? preferably applied in purification and / or desalination processes, said fluid F? preferably contaminated or salty or brackish water, sea, river, swamp or rainwater.

Since, however, other applications of the method according to the present invention are possible, said fluid F may be possible. be of any type according to specific needs.

Here, in particular, we wish to highlight the existence of industrial processes other than purification and / or desalination and which use small quantities of steam; for example, steam is used as an antioxidant process gas during the annealing phase of the copper wire in the wire enamelling processes for the windings of electric motors; another example ? offered by the agri-food sector, in the cooking of food with steam; in addition, the use of steam in small quantities? ? present in the paper industry, to separate cellulose from lignin.

In the aforementioned processes, said fluid F will be? preferably contaminated or salty or brackish water, sea, river, swamp or rainwater.

Said fluid F avr? preferably a temperature comprised between 5 ° C and 40 ° C, preferably it will be? at the ambient temperature of about 20 ° C.

As aforesaid, the fluid F flows from the tank 8, through the connection pipe 6 and the hole 5, into the interspace 3; preferably, the flow of fluid F coming from the tank 8? regulated by means of a valve 7 mounted on the connection pipe 6 and / or a septum of porous material, preferably hydrophilic, 14 inserted in the connection pipe 6.

We want to point out here that, although? up to now, a system for feeding water from said gravity tank 8 has been shown, ie by means of an elevated tank, in compliance with the concept of autonomy from electrical auxiliaries underlying the present invention. evident to the expert of the sector that can? likewise, a system for feeding water from said tank 8 equipped with a pump, preferably peristaltic, considering the flow rates involved, be provided.

Preferably, said thin film of said fluid F present in said interspace 3 has a variable thickness between 100 µm and 1,000 µm, preferably equal to 300 µm; preferably, said interspace 3 is made by inserting a thin frame or a thin spacer between said upper element 1 and said support 2.

Preferably, said device 16 reflecting solar radiation or other radiation R? a point or linear concentrator, parabolic or using Fresnel mirrors; pi? preferably, said reflecting device 16? a parabolic mirror in which the radiation R? collected and concentrated, and then redirected to planar structure 100, and more? precisely towards the face of said support 2 opposite to said interspace 3 and comprising said material 4 absorbing solar radiation or other radiation R, said face facing and in correspondence with the reflecting point (s) P of said reflecting device 16.

In this way, the planar structure 100 turns out to be a cavity? optically black almost ideal, and not? therefore it is necessary to resort to expensive optically absorbing materials.

Note that, although? the inverted configuration shown here - ie? with the light source or radiation coming from below? is the preferred one as it allows the use of concentrators by means of mirrors or other reflecting means, the expert in the field? certainly able to realize the non-inverted configuration - that is? with the face of said support 2 opposite to said interspace 3 and comprising said material 4 absorbing solar radiation or other radiation R positioned at the top and the concentrated light, for example, with a convex or Fresnel lens system which, however, typically , are characterized by lower optical efficiencies.

Preferably, said solar radiation or other radiation R has an intensity? variable between 100 W / m <2> and 2,000 W / m <2>, preferably equal to 600 W / m <2>.

In this way, the fluid F is heated in the interspace 3 and exits, in the vapor state V, through the duct (s) 13.

Preferably, said at least one duct 13 has a diameter ranging from 1 mm to 10 mm, preferably equal to 5 mm.

Preferably, the evaporation of said fluid F produces a quantity of of vapor V (defined with respect to a plane orthogonal to the sun's rays) variable between 0.1 kg / h / m <2> and 2.0 kg / h / m <2>, preferably equal to 0.6 kg / h / m <2>.

Optionally, said vapor V is directed towards a cold surface 15 where it condenses, and the condenses thus? obtained is collected and subsequently used. Preferably, the condensation of said vapor V produces a quantity? of variable condensate between 50% and 100% of the flow of steam produced. Preferably, called condensation? fresh and / or drinking water.

For greater thermal efficiency, that is? in order to limit the losses towards the external environment and, consequently, to increase the pi? possible the conversion of light / heat / vapor, pu? possibly use of the thermally insulating material 9, having a low conductivity value? thermal (for example, of the order of 0.04 W / (m * K)); said thermally insulating material 9 pu? be placed partly on said connection tube 6 and partly on said planar structure 100.

According to an alternative variant (not shown), the thermally insulating material 9 can? be replaced by a covering comprising a compartment in which? the vacuum was created, in order to guarantee the pi? low thermal transmission possible (as happens in Dewar jars); according to another alternative variant (not shown), the thermally insulating material 9 can? be replaced by a coating comprising a compartment filled with Phase-change material (PCM), such as for example paraffin waxes, in order to accumulate the thermal heat dispersed by the planar cell and thus make it available again during periods of less solar radiation and / or absence of radiation; according to a further alternative variant (not shown), the thermally insulating material 9 can? comprise a multi-layer coating, i.e. with a first compartment filled with phase change material, in direct contact with the upper element 1, and a second compartment in which? the vacuum was created, placed even more? above, that is, on the opposite side with respect to the upper element 1, capable of guaranteeing maximum thermal insulation.

Here it is considered important to note that among the aforementioned solutions, those that use phase change material allow to significantly lengthen the operating period of the planar cell according to the present invention, consequently obtaining an overall lengthening of the useful life of the plant to which this planar cell is associated.

Result? evident to the expert in the field that the insulating coating 9 will be able to? also be realized by means of other combinations of the described solutions; moreover, different solutions which allow to optimize the thermal balance, having equivalent functions and known to the expert in the field, are included in the scope of protection of the present invention.

Said thermally insulating material 9 can? also be used to create walls around said planar structure 100, with development downwards (purely by way of example, in FIG. 2 it is observed that these walls form a truncated cone at the top of which is the absorbent material 4) ; this expedient allows to create a stagnation zone around the hot part of the support 2 / absorbent material 4 assembly, which? able to hinder the upward convective thermal flows.

Thanks to the measures adopted in the method according to the present invention, the heat losses by conduction, convection and optical are reduced, respectively, by about 10%, about 10% and about 20% (compared to an optical system with transmission).

Consequently, very high conversion efficiencies of radiative energy into vapor are achieved, preferably of the order between 70% and 80%.

According to a much more embodiment? efficient, the condensing cold surface 15 can? be replaced with a heat regenerator or recuperator which, by exploiting the latent heat of condensation, performs a pre-heating and / or partial pre-evaporation of the fluid F entering the hole 5; this type of regenerator? It has been studied by the same Applicant and is the subject of a separate but contextual Italian patent application entitled? Device for thin film regenerative condensation, and relative method ?.

The method according to the preferred embodiment of the present invention provides for application to a desalination plant; this preferred embodiment of the method according to the present invention is described below more? in detail and specifically with reference to an example, which? intended as illustrative but not limitative of the present invention; the following example? was developed on the basis of experimental data.

Example: generation of steam in a planar structure by solar radiation. Consider a summer day, in which solar radiation? equal to 500 W / m2, and to use a parabolic tip concentrator with an absorbing surface equal to 0.04 m2 (defined on a plane orthogonal to the sun's rays). A planar cell, like the one proposed in this invention, has a square dimension of 3 cm by 3 cm and a cavity thickness of 200? M, is capable of producing approximately 27 g / h of steam, which correspond about 0.68 kg / h / m2. Consequently, depending on the quality? of the cold condensing surface 15, approximately 0.61 kg / h / m2 of condensation, which would correspond to an overall thermodynamic yield of approximately 80%.

Referring now to FIG. 2, it is observed that a system for the generation of vapor V in planar structure 100 by means of solar radiation or other radiation R, comprises:

- at least one planar structure 100 comprising, in turn:

? an upper element 1,

? a support 2,

? an interspace 3 between said upper element 1 and said support

2,

? a hole 5, e

? at least one duct 13,

where said hole 5? positioned on the face of said upper element 1 opposite said interspace 3 and in which the face of said support 2 opposite said interspace 3 comprises a material 4 absorbing solar radiation or other radiation R;

- at least one tank 8 containing a fluid F connected, by means of a connecting pipe 6, to said at least one planar structure 100 in correspondence with said hole 5, so that said fluid F pu? flowing into said interspace 3 therein forming a thin film; And

- at least one reflecting device 16 of solar radiation or other radiation R facing towards said at least one planar structure 100 so that said face of said support 2, opposite to said interspace 3 and comprising said material 4 absorbing solar radiation or other radiation R, faces and at the reflecting point (s) P of said at least one reflecting device 16, so that? the thermal energy released by said solar radiation or other radiation R on said planar structure 100, specifically on said face of said support 2 opposite to said interspace 3 and comprising said material 4 absorbing solar radiation or other radiation R, induces evaporation of said fluid F and the production of vapor V, which is made to escape through said at least one duct 13.

The system according to the present invention can? also include, optionally:

- at least one cold surface 15 towards which said vapor V, released through said at least one duct 13, is directed and on which its condensation occurs; And

- means for collecting the condensate produced to be used subsequently.

The system according to the present invention can? also include:

- a septum of porous material, preferably hydrophilic, 14 inserted inside said connection tube 6,

- thermally insulating material 9 located partly on said connection tube 6 and partly on said planar structure, e

- a regulating valve 7 positioned on said connection pipe

6.

Similarly to what reported above for the method according to the present invention, preferably:

- said material 4 absorbing solar radiation or other radiation R? an absorbent material with high efficiency, which can? be used to cover the face of said support 2 opposite to said interspace 3 (in this case preferably it is a coating of suitable oxides capable of guaranteeing the necessary selective coating properties, more preferably a layer of titanium dioxide and even more preferably it is a commercial titanium dioxide layer explicitly developed for solar applications (for example, the TINOX material produced by the German company ALMECO GmbH); preferably it is applied on said support 2 by physical vapor deposition (PVD, Physical Vapor Deposition); preferably it has a variable thickness between less than one? M and a few tens of? M, more preferably equal to 1-2? M) or can? constitute a coating layer of the face of said support 2 opposite to said interspace 3 (in this case it is preferably a coated metal sheet, more preferably a coated copper or aluminum sheet and even more preferably a copper sheet or aluminum coated with titanium dioxide; preferably it has a thickness ranging between 0.1 mm and 2.0 mm, more preferably equal to 0.2 mm; preferably it is fixed on said support 2 by gluing, welding and localized fusion );

- said upper element 1? hydrophilic, so as to be able to distribute the fluid F in the interspace 3 by capillarity; pi? preferably? hydrophilic and low conductivity thermal (for example, not exceeding about 1 W / (m * K)); even more? preferably? glass;

- said support 2? made with sufficiently conductive materials from the thermal point of view (for example, with thermal conductivity of the order of 300 W / (m * K)); pi? preferably? made of metal;

- said interspace 3 has a variable dimension between 100? m and 1,000? m, preferably equal to 300? m;

- said hole 5 has a diameter ranging from 4 mm to 50 mm, preferably equal to 10 mm;

- said at least one duct 13 has a diameter ranging from 1 mm to 10 mm, preferably equal to 5 mm;

- said fluid F preferably has a temperature comprised between 5 ° C and 40 ° C, plus? preferably? at the ambient temperature of about 20 ° C;

- said thin film of said fluid F present in said interspace 3 has a variable thickness between 100 µm and 1,000 µm, preferably equal to 300 µm; preferably, said interspace 3 is made by inserting a thin frame or a thin spacer between said upper element 1 and said support 2;

- said device 16 reflecting solar radiation or other radiation R? a point or linear concentrator, parabolic or using Fresnel mirrors; pi? preferably, said reflecting device 16? a parabolic mirror in which the solar radiation R? collected and concentrated, and then redirected to planar structure 100, and more? precisely towards the face of said support 2 opposite to said interspace 3 and comprising said material 4 absorbing solar radiation or other radiation R, said face facing and in correspondence with the reflecting point (s) P of said reflecting device 16;

- said solar radiation or other radiation R has an intensity? variable between 100 W / m <2> and 2,000 W / m <2>, preferably equal to 600 W / m <2>;

- the evaporation of said fluid F produces a quantity of of vapor V (defined with respect to a plane orthogonal to the sun's rays) variable between 0.1 kg / h / m <2> and 2.0 kg / h / m <2>, preferably equal to 0.6 kg / h / m <2>.

Preferably, said cold surface 15, on which the vapor V condenses,? formed by a conical slope, with a smooth surface able to make the drops of condensation flow and cause them to detach from the lower edge, which could be shaped in a spiral in order to facilitate the collection of the condensate itself.

Preferably, the condensation of said vapor V produces a quantity? of variable condensate between 50% and 100% of the flow of steam produced, depending on the quality? of the cold condensing surface 15.

Preferably, the condensate obtained is collected in a cylindrical gutter or other suitable collection means capable of receiving the drops which detach from the lower edge of the cold surface 15.

Preferably, the condensate collected? fresh and / or drinking water and is used for domestic use.

Preferably, said septum of porous material, preferably hydrophilic, 14? made of fabric; pi? preferably? made of cotton wool.

Preferably, said septum of porous material, preferably hydrophilic, 14? inserted inside said connection tube 6 in the vicinity of of said hole 5; in an alternative version (not shown), said septum of porous material, preferably hydrophilic, 14 extends up to the inside of the interspace 3, so? improving the distribution of the fluid F in the interspace 3 by capillarity; in a further alternative version (not shown), said septum of porous material, preferably hydrophilic, 14 completely fills the interspace 3, so? further improving the distribution of the fluid F in the interspace 3 by capillarity.

Preferably, said thermally insulating material 9? polymeric material; pi? preferably? polystyrene (polystyrene); if the costs allow it, even more? preferably said thermally insulating material 9? replaced by a covering comprising a compartment in which? has been created the vacuum (to reduce heat loss) or a compartment that? been filled with a phase change material (in order to accumulate and then recover the heat losses).

Preferably, said thermally insulating material 9? placed on the portion of said connection tube 6 comprising said septum of porous material 14.

Preferably, said regulating valve 7? of the type with precise flow regulation and? positioned on said connection pipe 6 in proximity? of said tank 8.

Preferably, said tank 8? placed in an elevated position with respect to said planar structure 100, so as to provide a gravity water supply system, consistent with the concept of autonomy from electrical auxiliaries underlying the present invention; alternatively, however,? It is possible to provide a pump, preferably peristaltic, to make said fluid F flow from said tank 8 into said interspace 3.

According to a much more embodiment? efficient, the cold condensing surface 15 can? be replaced with a heat regenerator or recuperator which, by exploiting the latent heat of condensation, performs a pre-heating and / or partial pre-evaporation of the fluid F entering the hole 5; this type of regenerator? It has been studied by the same Applicant and is the subject of a separate but contextual Italian patent application entitled? Device for thin film regenerative condensation, and relative method ?.

Similarly to the method according to the present invention, also the system according to the present invention can? preferably be applied to purification and / or desalination plants; however, it will result? evident to the expert in the field that the present steam generation system will be able to? be used in other types of systems such as, for example, copper wire enamelling systems used in the windings of electric motors (specifically, during the wire annealing phase, in which the steam is used as an antioxidant process gas ), food cooking lines (e.g. biscuits) and paper production plants (specifically to separate cellulose from lignin).

As can be deduced from the above, the innovative technical solution described here has the following advantageous characteristics:

- confinement of the water to be treated inside a thin film in order to significantly reduce its residence time and conductive thermal losses towards the outside;

- inverted configuration (ie with direct radiation from bottom to top) which allows the use of concentrators by means of mirrors or other reflecting means instead of lenses which, typically, are characterized by pi? low optical efficiencies;

- the same inverted configuration also allows? to create appropriate barriers to hinder the convective motions of the air in the vicinity? of the hot surface of the support assembly 2 / absorbent material 4, so? to reduce energy losses;

- significant reduction of the dispersing surface through which the thermal flows towards the environment pass thanks to the use of a thin planar structure, per unit volume of water in the evaporation chamber;

- maximization of the surface subject to solar radiation always thanks to the use of a thin planar structure, per unit? volume of water in the evaporation chamber;

- increase in optical efficiency as it does not require the use of transparent materials; And

- thanks to the intrinsic simplicity? and robustness and since no electrical input is required, the method and the device according to the present invention are particularly suitable for use in remote regions and for so-called? offgrid? applications.

From the description above? it is therefore evident how the described method and system allow to achieve the proposed aims.

? equally evident, to a person skilled in the art, that? It is possible to make modifications and variations to the solution described with reference to the attached figures, without thereby departing from the teaching of the present invention and from the scope of protection as defined by the attached claims.

Claims (10)

CLAIMS 1. Method for the generation of vapor (V) in planar structure (100) by solar radiation or other radiation (R), comprising the following steps: to. provide at least one planar structure (100) comprising: ? an upper element (1), ? a support (2), ? a gap (3) between said upper element (1) and said support (2), ? a hole (5), e ? at least one duct (13), in which said hole (5)? positioned on the face of said upper element (1) opposite said interspace (3) and in which the face of said support (2) opposite said interspace (3) comprises a material (4) absorbing solar radiation or other radiation (R ) (step 101); b. providing at least one reservoir (8) containing a fluid (F) (step 102); c. providing at least one reflecting device (16) for solar radiation or other radiation (R) (step 103); d. connecting said tank (8) containing said fluid (F), by means of a connecting tube (6), to said at least one planar structure (100) in correspondence with said hole (5) (step 104); And. make said fluid (F) flow in said interspace (3), so? making a thin film of said fluid (F) (step 105); f. position said at least one planar structure (100) facing towards said at least one reflecting device (16) so that said face of said support (2), opposite said interspace (3) and comprising said material (4) absorbing solar radiation or other radiation (R) faces and at the reflecting point (s) (P) of said at least one reflecting device (16) (step 106); g. induce the evaporation of said fluid (F) and the production of steam (V) by releasing the thermal energy of said solar radiation or other radiation (R) on said planar structure (100), specifically on said face of said support ( 2) opposite said interspace (3) and comprising said material (4) absorbing solar radiation or other radiation (R) (step 107); And h. causing said vapor (V) to escape through said at least one duct (13) (step 108). Method according to claim 1, further comprising the following steps: the. providing at least one cold surface (15) (step 109); j. directing said vapor (V), escaped through said at least one duct (13), towards said at least one cold surface (15), on which condensation occurs (step 110); and k. collect the condensate produced for subsequent use (step 111). Method according to claim 1 or 2, wherein said upper element (1)? hydrophilic and wherein said material (4) absorbing solar radiation or other radiation (R)? used to cover the face of said support (2) opposite to said interspace (3) or constitutes a coating layer of the face of said support (2) opposite to said interspace (3). Method according to any one of the preceding claims, wherein said fluid (F)? contaminated, salty or brackish water. Method according to any one of the preceding claims, wherein said thin film of said fluid (F) present in said interspace (3) has a thickness varying between 100 µm and 1,000 µm, preferably equal to 300 µm. Method according to any one of the preceding claims, wherein said solar radiation or other radiation (R) has an intensity? variable between 100 W / m <2> and 2,000 W / m <2>, preferably equal to 600 W / m <2>. 7. Method according to any one of the preceding claims, wherein the evaporation of said fluid (F) produces a quantity of of vapor (V) (defined with respect to a plane orthogonal to the sun's rays) variable between 0.1 kg / h / m <2> and 2.0 kg / h / m <2>, preferably equal to 0.6 kg / h / m <2>. 8. System for the generation of steam (V) in planar structure (100) by solar radiation or other radiation (R), comprising: - at least one planar structure (100) comprising, in turn: ? an upper element (1), ? a support (2), ? a gap (3) between said upper element (1) and said support (2), ? a hole (5), e ? at least one duct (13), in which said hole (5)? positioned on the face of said upper element (1) opposite said interspace (3) and in which the face of said support (2) opposite said interspace (3) comprises a material (4) absorbing solar radiation or other radiation (R ); - at least one tank (8) containing a fluid (F) connected, by means of a connection pipe (6), to said at least one planar structure (100) in correspondence with said hole (5), so that? said fluid (F) pu? flow into said interspace (3) therein forming a thin film; And - at least one reflecting device (16) of solar radiation or other radiation (R) facing said at least one planar structure (100) so that said face of said support (2), opposite to said interspace (3) and comprising said material (4) absorbing solar radiation or other radiation (R), faces and in correspondence with the reflecting point (s) (P) of said at least one reflecting device (16), so that? the thermal energy released by said solar radiation or other radiation (R) on said planar structure (100), specifically on said face of said support (2) opposite to said interspace (3) and comprising said radiation absorbing material (4) solar or other radiation (R), induces the evaporation of said fluid (F) and the production of steam (V), which is made to escape through said at least one duct (13). System according to claim 8, further comprising: - at least one cold surface (15) towards which said vapor (V), which has escaped through said at least one duct (13), is directed and on which its condensation occurs; And - means for collecting the condensate produced to be used subsequently. System according to claim 8 or 9, further comprising: - a septum of porous material, preferably hydrophilic, (14) inserted inside said connection tube (6), - thermally insulating hollow material or lining (9) placed partly on said connection tube (6) and partly on said planar structure (100), and - a regulating valve (7) positioned on said connection pipe (6).