EP3002369A1

EP3002369A1 - Irrigation, draining and/or heating system

Info

Publication number: EP3002369A1
Application number: EP14425121.2A
Authority: EP
Inventors: Vito Lavanga; Antonio Sparacino
Original assignee: Energy Savings For Agricolture & Environment SRL In Liquidazione
Priority date: 2014-10-03
Filing date: 2014-10-03
Publication date: 2016-04-06
Also published as: CN107257874A; WO2016050920A1; EA032278B1; CN107257874B; EA201790780A1

Abstract

An irrigation, draining and/or heating system of a surface, comprising:
-a tank (215) defined by a water-proofing sheath (214) housed in an excavation in the ground;
-a water grid (201) located inside said tank (215), comprising at least one inlet module (202) and at least one outlet module (203);
-an outer water reservoir;
-one or more inlet (260) and outlet (261) connections, connecting said water grid (201) to said outer water reservoir; and
-a draining soil to fill said tank.
Each of said at least two modules comprises an impermeable main pipe (204) from which a series of permeable conduits (205) emerges, where said conduits lie on the same horizontal plane of said main pipe.

Description

The present invention relates to an irrigation, draining and/or heating system of a surface, comprising:

a tank (215) defined by a water-proofing sheath (214) housed in an excavation in the ground;
a water grid (201) located inside said tank (215), comprising at least one inlet module (202) and at least one outlet module (203);
an outer water reservoir;
one or more inlet (260) and outlet (261) connections, connecting said water grid (201) to said outer water reservoir;
a draining soil to fill said tank;

characterized in that

FIGURE 2

BACKGROUND OF THE ART

There is a strongly felt need to have systems for efficiently heating a ground, both for sports and for agricultural and industrial purposes.
For example, in sports applications, such as a football ground, by virtue of the heating of a grass playground, snow and ice melt in an efficient manner, so as to make the ground practicable even during the winter season. Furthermore, a heating during the winter season prevents the damages to the turf that often the frost involves.
There are heatable football grounds, where the heating is mainly based on buried electric cables. Other buried heating plants comprise systems of pipes in which hot water is circulated. Again, hot water or steam heating solutions are proposed.
The systems of buried electric cables have the drawback of having to necessarily use large amounts of higher energy. Therefore, this solution is not very efficient from an energy viewpoint, and it is particularly expensive.
The use of water-mediated heat undoubtedly allows a great flexibility in selecting the energy source. However, compared to the use of electric cables, it has the heavy disadvantage related to the risk of leakages from the pipes and the need of a challenging maintenance.
A great energy expenditure is also due to the fact that the heat is unnecessarily lost in the underlying layers of the soil, substantially due to the effect of the gravimetric run-off of rainwater.
In addition, the prior art systems, which are based on electric cables or tubes in which the hot water flows, lead to an uneven heating of the soil, which is reflected in an uneven growth of the turf, where the grass is luxuriant at the cables or tubes, and less luxuriant at other points, with a characteristic "wave-like" growth.
In addition to the problem of having a soil that can be uniformly heated with an energy-efficient system, a further problem that is strongly felt in the playgrounds relates to the drainage.
US patent No. 3.908.385 discloses a system of pipes that are buried below the playground, which are partially water-permeable to promote the draining of a natural grass playground. The system comprises a water-impermeable membrane lied on a compacted subsoil, coated by a sand filling layer with a draining network buried therein, and a turf on top. Some of the pipes of the draining network are permeable to fluids, and allow a draining by gravity. A void can be applied to the grid to implement, for example during heavy rain periods, the drainage that usually occurs by gravity.
WO96/25035 discloses a pipe grid buried under a surface, where a series of pipes in parallel are connected to a series of conduits perpendicular thereof and located on top of them, where said conduits are water-permeable. The water from the conduits passes to the pipes, which drain by gravity, or, where necessary, with the aid of a vacuum. In an embodiment, some of the pipes have a double function, i.e., they can be disconnected from the draining system and connected, in a substantially closed loop, or also for the permeability of the conduits, to a boiler, so that in the same hot water is introduced which will then flow out by the draining system and, partially, it will go back to the boiler.
Again, the need is strongly felt, to be able to irrigate a soil without wasting water.
Again, the need is strongly felt, to have floor heating systems that are efficient from the energy viewpoint, and which allow maximizing the use of the energy produced by renewable sources for industrial applications.
The object of the present invention is to provide a system that allows having a homogeneously heated surface and, in a preferred embodiment, with a proper draining, characterized by a strong respect for the environment, both in terms of energy efficiency and containment of water consumptions.

SUMMARY OF THE INVENTION

It is the object of the present invention an irrigation, draining and/or heating system for a soil, where said system comprises:

a tank defined by a water-proofing sheath housed in an excavation in the ground;
a water grid, located inside said tank, comprising at least one inlet module and at least one outlet module;
an outer water reservoir;
one or more inlet and outlet connections connecting said water grid to said outer water reservoir;
a draining soil to fill said tank;

characterized in that

Further characteristics and advantages of the present invention will be more clearly apparent from the description and the following figures.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows a horizontal section of the water grid;
Fig. 2 shows a vertical section of the soil in which the water grid of the present invention has been positioned;
Fig. 3 shows a perspective view of the outer water reservoir;
Fig. 4 shows a top view of the outer water reservoir;
Fig. 5 shows a block diagram of an embodiment of the system of irrigation, draining and heating according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The irrigation, draining and/or heating system of the present invention comprises:

a tank defined by a water-proofing sheath housed in an excavation in the ground;
a water grid located inside said tank, comprising at least one inlet module and at least one outlet module;
an outer water reservoir;
one or more inlet and outlet connections connecting said water grid to said outer water reservoir;
a draining soil to fill said tank;

characterized in that

The Fig. 1 schematically illustrates a horizontal section of a water grid 1 composed of two modules, an inlet module 2 and an outlet module 3. Each of said modules 2 and 3 comprises a main pipe 4 to which a series of conduits 5 is connected by junctions 6, where said conduits 5 are approximately perpendicular to said main pipe 4 and lie on the same horizontal plane. Said conduits 5 interleave along the length of said main pipe 4. Said main pipe 4 is water-impermeable. Said conduits 5 are water-permeable. Said modules, assembled to produce the water grid, lie on a single horizontal plane and they are parallel and mutually opposite. I.e., the modules are positioned so that the main pipes 4 are mutually parallel and the conduits 5 of an inlet module 2 insert in the spaces available between the conduits 5 of an outlet module 3. I.e., an inlet module 2 and an outlet module 3 are positioned so that the teeth of a comb (where the comb represents a module) are interleaved to the teeth of the comb flanking it.
Said main pipes 4 have an open end 7 and the opposite end 8 is closed. Once assembled in the water grid, the open end 7 of the main pipe 4 of the inlet module 2 is in a position that is diametrically opposite the open end 7 of the main pipe 4 of the outlet module 3.
In the water grid 1, 201 of the present invention, a conduit 5, 205 does not intersect other conduits 5, 205 emerging from the same main pipe 4, 204, nor with conduits 5, 205 emerging from main pipes 4, 204 belonging to another module. A conduit 5 is connected by a junction 6 to a main pipe 4, and it does not intersect in other points with the same or other main pipes 4.
Said main pipes 4 are preferably made of PVC or the like, and have a diameter suitable to the extension of the ground to be heated and a length that preferably takes the entire length or the entire width of the ground on which the system is installed.
Said conduits 5 are preferably made of PVC or the like, and they have a diameter and permeability that are suitable to the dimension of the ground to be conditioned.
By way of example, where the soil on which the system is installed has the dimensions of a football playground, said main pipes 4 have such a length as to cover the ground throughout the length thereof, approximately 100 m, and a diameter ranging between 150 and 250 mm, preferably about 200 mm. Said conduits 5 have a length of about 60 m, and a diameter ranging between 60 and 100 mm, preferably about 80 mm. Where the area to be covered is that of a football ground, preferably said water grid is formed by a single inlet module and a single outlet module as described above. In this embodiment, each of said main pipes 4 has the conduits 5 preferably emerging at a distance of about 10 meters from one another, so that in the two modules a comb, an inlet module, and an outlet module, which mutually opposite areas, a conduit of an inlet module 2 is at a distance of about 5 meters from a conduit of an outlet module 3.
In Fig. 2 a vertical section of a ground is set forth, in which the finding of the present invention has been laid. A tank 215 containing the water grid 201 comprising at least one inlet module 202 and at least one outlet module 203 is housed in an excavation in the ground and is defined by a water-proofing sheath 214 covering the bottom and the side walls of said excavation. Said excavation, hence said tank 215 have dimensions suitable to the thermal and irrigation regimes to be achieved. In particular, said tank 215 has a surface dimension equal to the surface area in which the object of the present invention is to be achieved, and a depth 211 ranging between 30 and 150 cm, preferably between 50 and 80 cm.
Said water-proofing sheath 214 is preferably made of PVC, polyethylene, or the like.
The draining soil is preferably composed of gravel. In said tank 215, under standard operating conditions, the stratigraphy of said soil is as follows: a gravel layer 218, immersed in water, and a dry gravel layer 219, where the dry gravel layer 219 is arranged on top of said gravel layer 218 and the water level filling said tank 215 up to the overflow level 213, said overflow level 213 substantially separates the gravel layer 218 from the dry gravel layer 219, keeping the water level in said tank within said overflow level, hence keeping said dry gravel layer 219 dry. Said water grid 201 is located inside said gravel layer 218.
In a preferred embodiment, on the bottom of said tank 215, under said gravel layer 218, there is a sand layer 216 and said water grid 201 is laid on top of said sand layer 216. Optionally, a fabric 217is present between said sand layer 216 and said water grid 201, preferably, a non-woven fabric. Where present, said sand 216 and/or said fabric 217 perform the function of preventing possible edges of sharp stones that can be present in the gravel layer 218 from damaging the sheath 214 on the bottom of the tank 215 upon reaching it.
Still more preferably, clay clods and/or clay soil are in direct contact with said sheath 214 on the bottom of the tank 215. Where present, said clay clods and/or clay soil act as natural water-proofing materials of the bottom of said tank 215, optimizing the water insulation of said tank 215.
The water grid 201 in the tank 215 is buried in the gravel layer 218, where the gravel occupies the spaces left free by the modules that compose said water grid 201. Preferably, said gravel has a size from 10 to 50 mm. Under standard operating conditions, said gravel layer 218, hence said water grid 201 and, where present, said sand layer 216 are completely immersed in the water.
In the embodiment of Fig. 2, there is a cultural soil layer 220 on top of said dry gravel layer 219. Preferably, said dry gravel layer 219 and said cultural soil layer 220 are separated one from the other by fabric 221. In the embodiment illustrated in Fig. 2, grass 273 is on top of said cultural soil layer 220. Where present, said fabric 221 located between the dry gravel layer 218 and the cultural soil 220 performs the function of preventing to the roots from passing from the cultural soil to the underlying gravel layer, to exclude an elongation of the roots up to the overflow level 213, hence an immersion in the water of the same roots.
On the side walls of said tank 215, at the level referred to as the overflow level 213 of said tank 215, there is at least an outlet 221 of at least one overflow conduit 222.
Furthermore, on the same side walls, there is the outlet 259 of at least one inlet conduit 260 and the outlet 262 of at least one outlet conduit 261, where said inlet conduit 260 consists in at least one pipe that inserts onto the opening 207 of the main pipe 204 of the inlet module 202, and said outlet conduit 261 consists in at least one pipe that inserts onto the opening 207 of the main pipe 204 of the outlet module 203. Said inlet and outlet conduits join the water grid to an outer water reservoir. Said outlets 221, 259 and 262 on said side walls do not alter the impermeability of said tank, are suitably sealed so as to allow exclusively the passage of the conduits.
Said sand layer 216, where present, has a thickness of about 20 cm, preferably about 10 cm, preferably about 5 cm. Said gravel layer 218 has a thickness 270 ranging between 10 and 50 cm, preferably about 30 cm. Said dry gravel layer 219 has a thickness 271 ranging between 1 and 20 cm, preferably between 5 and 15 cm, even more preferably about 10 cm. Said cultural soil layer 220, where present, has a variable thickness, up to 30 cm, preferably about 20 cm. Said overflow level 213 is located on top of said gravel layer 218, inside the thickness 271 occupied by said dry gravel layer 218.
In the system of the present invention, said water grid is in hydric connection with an outer water reservoir. Said outer water reservoir, forming with said water grid and said draining soil an almost closed circuit of culture water as best described below, is a reservoir suitable to heat said culture water. Preferably, said outer water reservoir heats said culture water through coils running therethrough, where, in said coils, technical hot water coming from a thermal plant is circulated. In a preferred embodiment, said outer water reservoir 380 and 480 is represented in the Figs. 3 and 4, in a front view and a top view, respectively. Said outer water reservoir 380 and 480 is a reservoir, preferably being in the form of a parallelepiped. Said reservoir comprises an outer case 385, 485 containing a structure 386, 486 therein, which follows the side profile thereof, thereby creating a hollow space 381, 481 between the side walls of said outer case 385, 485 and the walls of said structure 386, 486. Said structure 386 is open on the bottom, so that said hollow space 381, 481 is in direct communication with the inner volume of said case. Coils 382, 482 are contained in said hollow space 381, 481. Hot water is circulated in said coils 382, 482, which water referred to as technical hot water, provided by a thermal plant, with inlet tubes 390 opening into the coils and outlet tubes 391 bringing the technical water back to said plant. At least one outlet conduit 361, 461 coming from the at least one outlet module 205 of the water grid 201 reaches the hollow space 381, 481; said at least one outlet conduit 361, 461 ends in said hollow space 381, 481 with an open end, optionally controlled by a valve. This allows that, the water, referred to as culture water converges from the water grid arranged in the tank inside said hollow space 381, 481. On the bottom of said outer case 385 a pump 383, 483 is located, connected to at least one inlet conduit 360, 460 exiting said outer water reservoir to connect to the open end 7, 207 of said at least one inlet module 2, 202 in said hydric 1, 201. Said culture water, which is in contact with said coils 382, 482, heats and, with the aid of said pump 383, 483, said heated culture water is inserted, through said inlet conduits 360, 460, in the inlet module of said water grid.
Said outer water reservoir is located in the proximity of the soil in which the system of the present invention is laid, at a greater depth than the bottom of the tank of the present invention, so that the culture water collected by the outlet conduits converges in said outer water reservoir by a natural fall.
Preferably, said thermal plant is supplied by renewable sources. In an alternative and/or additional embodiment, said technical hot water comes from a boiler.
Preferably, said coils receive technical water from said plant at a temperature ranging between 20 and 50° C, preferably between 30 and 45° C, even more preferably at about 35° C.
Said culture water exits the outer water reservoir and enters said water grid at a temperature ranging between 5 and 40° C, preferably between 10 and 25° C, even more preferably at about 15° C.
Said outer water reservoir receives and brings back to the water grid the culture water that, in an embodiment, can be used also for the irrigation of the cultural soil arranged on top of said tank. To this aim, to allow a fine control of the cultural conditions, said outer water reservoir will contain suitable probes to monitor the pH and concentration of elements of interest. Where the need arises, in said outer water reservoir composts and/or fertilizers in appropriate amounts can be added in order to subsequently insert them into the soil.

Operating scheme.

The culture water of the present invention moves in a substantially closed circuit. The circulation circuit of the culture water in the system of the present invention is schematically illustrated in Fig. 5.
An outer culture water reservoir 501 supplies water in the water grid, through the conduit that inserts in the open end of the main pipe comprised in the one or more inlet modules 502 that are present in said water grid. From said one or more inlet modules 502, the water passes to the surrounding soil 504, said passage being mediated by the permeable conduits that are present in the inlet module. In the system of the present invention, one can easily consider that all the water present in the soil 504 re-enters in the circulation via the permeable conduits of the one or more modules of outlet 503 comprised in said water grid. Only a usually negligible part of said culture water is lost, through the surface of the tank, in the atmosphere 505 by evaporation. Said outlet modules 503 bring the water back into said outer water reservoir 501, which outer reservoir will re-introduce the same water in said inlet modules 502, subject to a preheating of the same.
The soil 504 not only releases water to the atmosphere 505, but also receives water from the atmosphere 505, for example during rainfalls. Where the exchange of soil water 504 towards the atmosphere 505 is unbalanced, and the water present in the soil 504 is in excess, said excess water passes, via the overflow conduits, into a reservoir 506. The water contained in said reservoir 506 is stored and remains available for future uses, for example, to restore the levels of culture water in said outer water reservoir 501, where an imbalance to the opposite direction would occur. Where the present solution subtends to sport or agricultural cultured soil that need irrigation, the water for the irrigation is withdrawn from the same outer culture water reservoir, which water will reenter the system once it reaches the soil 504, hence the outlet modules 503.
As pointed out in the scheme of Fig. 5 and in the description of the previous paragraph, the culture water of the solution of the present invention is characterized in that it is contained in a substantially closed circuit, where said water passes from the outer water reservoir to the tank and back to the outer water reservoir, to be recirculated again. The outwardly opening of the system is given by the tank surface and the overflow openings which are present in the tank adjust possible excesses of water in the system.
With reference to the Figs. 2 and 4, the culture water, passing from the permeable conduits of said at least one inlet module 202 to the gravel layer 218 fills the tank 215 up to the level of the overflow openings 213, thereby covering the gravel layer 218. The culture water present in the tank, and continuously introduced therein by said at least one inlet module 202, finds, as its preferential and exclusive outlet path, the passage through the permeable conduits of the outlet module 203, through the which is passes into the conduits 261 and is conveyed into the thickness 481 of the outer water reservoir 480 to be heated. The pump 483 brings the water from said outer water reservoir back to the tank through the conduit 460, 260. Said outer water reservoir 380, 480 is located at a greater depth of the soil than the bottom of the tank 215, so that the water returning to the outer water reservoir through the conduit 261 returns there by virtue of the communicating vessels principle. The solution of the present invention, proposing the arrangement of the at least two modules, an inlet one and an outlet one, to give a water grid of at least two intersecting combs, where said modules are immersed in a draining soil, allows the water entering through inlet module to converge in the outlet module, leaving the tank filled with water up to the level of the overflow openings. This is made possible by the particular configuration and arrangement of the modules and the stratigraphy of the soil in the tank proposed in the present invention. On the energy viewpoint, the path in which the water selects to pass in a system having the described characteristics, once it has diffused in the tank and has infiltrated the gravel layer, is to pass to the permeable conduits of the outlet module. This occurs because the described characteristics make said path energetically favorable compared to having to climb in the dry gravel layer on top. It is by virtue of the optimization of the water grid and the adopted stratigraphy that the culture water follows a given path that brings it to homogeneously distribute in the tank coming out from the conduits of the inlet module and pointing towards the conduits of the outlet module. Therefore, the solution of the present invention surprisingly allows having tank with a homogenous temperature in each point thereof. This homogeneity is advantageously obtained where a water grid composed of only one inlet module and only one outlet module that are suitably sized subtend the entire area to be treated. The tank at a homogenous temperature transmits heat to the dry gravel layer located on top of the water-immersed gravel layer. The heat is transmitted through said dry gravel layer by conduction and also by the action of the water vapor produced by the water present in the tank.
The system of the present invention allows having a cultural soil resting on a tank that is hydrically insulated from the surrounding compact subsoil, where said tank is filled with draining material immersed, up to a level referred to as a overflow level, in water at a controlled and homogeneous temperature.
A level of water at an homogenous temperature under the cultural soil ensures an even diffusion of the heat to the same soil. Furthermore, the cultural soil will have excellent draining abilities, exactly due to the fact that the water level is always controlled by said overflow openings, which do not allow the water to reach excessive and undesired levels under the cultural soil. The solution of the present invention allows a complete and precise control of the levels of culture water that are present in the tank. In a preferred embodiment, said system of overflow openings that usually operates based on the communicating vessels principle, without any energy consumption, will be able to be connected to a system of pumps, so as to be able to ensure the maintenance of the proper water level in the tank also, for example, during period of intense and continuous rain.
Again, the presence of a tank containing water under the cultural soil ensures a constant and optimal humidification of the soil.
The system of the present invention allows, with a single water grid, the concomitant management of the draining and heating of a soil, without the need for dedicate pipes for one or another functions, or without the need for valves that divide of the water grid, where applicable, so as to dedicate them alternatively to the draining or heating functions. Since the water grid and the outer water reservoir compose a substantially closed circuit, the system of the present invention ensures the containment of the water consumptions.
Furthermore, the system of irrigation, draining and heating of the present invention allows an optimal use of renewable energy sources. In fact, not only the temperature of the soil is provided by water, but by not very hot water. In fact, the solution described herein surprisingly allows, compared to the solutions of the prior art, in which hot water is circulated in coils arranged under the ground, using water at a temperature lower than that necessary in the coils, while keeping the temperature desired at the surface constant. The distribution of the water at an homogeneous temperature and the stratigraphy of the soil present in the tank of the present invention allow obtaining an even heating of the surface with water at a temperature lower than the temperatures that are used in the prior art.
This aspect ensures the maximum usability of renewable energy sources when applied to the plant, particularly, solar energy sources.
In a preferred embodiment, the technical water present in said coils running inside the thickness of the outer water source is provided at a suitable temperature by a heat pump. Such heat pump will maximize the use of the hot water obtained, for example, by solar panels or a thermal insulation coating, as described below. In a further embodiment, the hot water produced by said renewable sources will be able to be stored in the maximum production times inside a thermal well, described below, in order to be subsequently conveyed to the heat pump, for example, during night hours.
The thermal insulation coating: the application on the outer walls of a building of one or more layers of a bumped sheath with a suitable thickness, in which at least the first layer has bumps facing the wall to be protected. Aeration grids are arranged, which put the air gap between the wall and the sheath in communication with the external air and performing the function of level the inner pressure with the atmospheric one. Therefore, by a suitable number of couplings, a sheet having a zigzag profile is applied, for example a corrugated aluminum sheet, with the back of the Greek frets facing the sheath and with the Greek frets arranged in the horizontal direction, so as to create horizontal channels preventing the vertical movement (upward streams) of the air contained therein. Inside the Greek frets a pipe containing a heat-carrying fluid is laid, ideally, a coil running through the entire or part of the wall coated by the thermal coating. Subsequently, a thermowelded grid is applied, which is shaped according to the necessary thicknesses, with the suitable number of coupling points, with adhering function of the successive inert-based plasters (mainly based on sand and concrete, with high thermal conductivities), for a layer of several centimeters, optionally in multiple applications. Then one proceeds to the desired finishing, applying colors and coatings with suitable thermal properties. The possible application of honeycombed translucent supports will enhance the absorbing function, on suitable heights of surfaces functional to the needs to be met. The suitable dimensioning and finishing of the outer layer will promote the sound insulation.
For a detailed description of the thermal coating, reference is made to the document WO2010/143161 .
By applying the thermal insulation coating to the system of the present invention, the heat-carrying fluid circulating in the thermal coating comprise all or a part of the technical water circulating in the coils present in the culture water source. In an embodiment, the tube of the thermal insulation coating containing the heat-carrying fluid, heated by the sun incident onto the surface of the thermal insulation coating, is put in communication with the below-described hot thermal well, for example by directly percolating the fluid into the thermal well; alternatively, it is directly introduced in the coils that heat the water of the culture water source.
The thermal well is a container for inerts which are crushed in a suitable size, in variable volumes and geometries, capable of performing, by virtue of preset surfaces/volumes ratios, functions of energy storage and/or exchange. Such inert materials can be, for example, water-immersed gravel or stones, generally local, inexpensive materials which, by virtue of their physical-chemical characteristics, give a heat capacity to the assembly that is substantially equivalent to that of water, having, compared to water, about a halved specific heat, but approximately double densities. Another important characteristic of these materials is that they have a higher thermal conductivity, preferably approximately double or even higher, compared to the thermal conductivity of water.
By way of example, the thermal well is a concrete case, for example, composed of a set of vibrated concrete rings, made impermeable and sealed, hermetically closed on the bottom and the lid. The case contains therein a mass of inert material of variable size (for example, 20-30 mm), with a high thermal capacity that makes this material preferable to the water for its higher static properties advantages and thermal excursions and good thermal conductivity, to maximize the thermal conduction outwardly through thermal bridges made of the concrete of the case and the inerts contained therein, which extends the thermal property to the surrounding mass.
The thermal exchange occurs through the percolation of the water in the inert mass, withdrawing and releasing the heat-carrying liquid preferably in diametrically opposite points, or creating a tortuous path of the heat-carrying liquid through the inert mass, and preferably arranging homogenization compartments by virtue of the laying, in the lower or upper part, of inerts having a larger size or spacer members, such as, for example formworks for ventilated under-floor cavities.
It is important that both the dip-pipes and the drain pipes are submersed under the water level in the thermal well, to keep the circuit closed, hence to reduce, or even eliminate, the power required for the recirculation pump. The circuitry is thus obtained communicating vessels, without prevalence, using customary hydraulic techniques for grouting the recirculation pumps.
The manufactured article, by virtue of the properties of the inerts contained and the containing concrete, provides a remarkable thermal excursion, being able to operate without problems between -50° C and 250° C, with temperature extremes mainly limited by the possibility of lowering the freezing limit or raising the boiling point of the heat-carrying fluid by the use of suitable diathermal substances.
The manufactured article has a thermal capacity of about 1.14 kWh/(m³.K). Therefore, considering a temperature delta of 5° C, the system of the invention provides a theoretical power of about 5.7 kW/m³.
For a detailed description of a thermal well, reference is made to the document WO2011/143161 .
One or more renewable heat sources are associated to the thermal well.
In an embodiment of the system of the present invention, one or more thermal insulation coatings and/or one or more solar panels and, optionally, a thermal well are associated to the system. The heat-carrying fluid that is heated by the renewable energy sources, also referred to as technical water, will optionally flow into the thermal well, so as to maintain the temperature level of said water as high as possible. A heat pump will lead the technical water to the desired temperature for the introduction into the coils present in the culture water sources.
It is a further aspect of the present invention a method for heating an agricultural and/or industrial and/or sport surface, comprising:

arranging an excavation in the ground;
coating said excavation with a water-proofing sheath to create a tank, arranging overflow openings on the side walls of said tank;
locating inside said tank, in a lower position with respect to said overflow openings, a water grid comprising at least two modules, an inlet module and an outlet module, where each module comprises an impermeable main pipe from which a series of permeable conduits branch, which lie on the same plane of said main pipe;
filling said tank with a draining soil;
optionally, arranging a concrete pour on top of said draining soil.

The system of the present invention is an economic and ecological solution, simple to be implemented, and needing low maintenance, allowing responding efficiently with a single intervention and a single water grid to three key needs: irrigation, draining, heating of a cultural soil.
The installation of the system of the present invention is fast and inexpensive, requiring only a shallow excavation. The use of the evenly distributed water in a tank ensures an even heating of the soil, preventing the wave-like growth observed with the common heating systems with electrical cables or pipes. Furthermore, the presence of a tank, where the same is suitably insulated, prevents the heat leakage to the outside of the strictly necessary area.
Furthermore, the presence of gravel at a higher level with respect to the level where the overflow openings are located ensures the presence of a gravel that will be mostly dry. This dry gravel, by warming due to the hot water below, will serve as a radiator, further optimizing the heating efficiency of the present system.
The modules, also since they comprise water-permeable portions, are easy to manage and require little maintenance, any leaks, also where they should happen, do not in fact involve any problems in the system on the whole.
The placement of modules comprising a main pipe and conduits arranged in a comb-like manner provides, compared to the solutions with permeable conduits described in the prior art, the following benefits in addition to those that have emerged in the previous paragraphs of the present description:

the arrangement of main pipes and conduits on the same plane facilitates the installation;
in the settling step, they do not bring problems of soil subsidence: the tank bottom being well leveled, once the modules and the draining stratigraphy have been laid, it is possible to settle the surface by using rollers or the like, given the strength of the material employed. Also, no further settlement problems arise over time;
there is no need of having reinforcement plaques at the level of the junctions, as the junctions, being positioned between the sand and gravel, exploit the dampening effect of the material that surrounds them, thereby standing up well to the stresses;
the water in the tank filled with draining material, together with the control system of the same water level obtained by the overflow openings, further ensures an excellent draining ability to the soil, in addition to ensuring a constant humidity thereof. Under particular climatic conditions, where the water levels in the tank decreases too much, the possibility is in any case provided to restore them by tapping into the water reservoir provided for in the vicinity of the plant.

In an embodiment, in said reservoir also the rainwater collected from the eaves of the surrounding buildings will be able to be merged.
The system of the present invention is in fact a closed system, where the transfer of water to the atmosphere occurs only by evaporation. The closed system prevents products, such as composts or fertilizers used on the soil and that might otherwise contaminate the groundwater, from being dispersed into the surrounding environment, for example by run-off,
The system of the present invention lends itself to multiple applications. Particularly, a first application is in sports grounds. For these applications, such as, for example football grounds, grass tennis courts, the turf is seeded on top of the gravel layer and the cultural soil or, alternatively, grass sods or also synthetic grass sods are arranged, which are suitable for the subsequent seeding thereon of a turf.
In these applications, suitably a thermal insulation coating and/or solar panels will be able to be applied on adjacent structures, such as locker rooms or gyms, so as to maximize the energy efficiency of the plant.
A further application is for cultural soils. The present invention allows a fine control of the water needs of specific crops and, by virtue of the possibility to heat the soil, it allows culturing also out of season or in climate areas in which, in the absence of the solution of the present invention, would not be favorable to certain crops.
The solution of the present invention, being an almost closed system from the hydric point of view, allows monitoring and continuous adjusting the nutrients-fertilizers needed for the specific crop.
Conveniently, to the surface that is drained, irrigated and heated by the system of the present invention, a cover will be able to be associated, for example, a football for sports grounds, or a greenhouse, so as to maintain a certain degree of heating and, where desired, as it will be seen below, also in the environment.
Furthermore, the present invention is suitable for industrial applications. In this embodiment, the dry gravel layer is the most superficial layer. Over such soil, a greenhouse for example will be able to be build. The surface of the dry gravel layer will be the walkable surface, on which the benches on which to keep the pots of plants will be able to be laid at a suitable distance. Due to the heat that emanates from the subsoil and cover, during the cold season the embodiment allows having an environment at a temperature higher than the outside with a very low energy cost. Not only that, the evaporation of the water through the dry gravel layer will ensure also a certain degree of humidity inside the greenhouse.
Furthermore, considered the very high capacity for square meter of the surface under which the system of the present invention has been implemented, a further embodiment provides a dry gravel layer with a thickness lower than 10 cm, for example, of 2-4 cm, above which the reinforced concrete will be poured. Said surface will form the floor of an industrial warehouse, with very favorable energy costs for the heating and that can depend also exclusively on renewable energy sources. In fact, the common radiant floors operate at temperatures normally ranging between 28 and 32° C, while with the solution of the present invention it is possible to achieve the same results by operating at temperatures ranging between 22 and 26° C. The presence of a reinforced concrete cover blocks the water evaporation, thus avoiding the formation of humidity in the environment, which is undesired in this particular case.

Claims

An irrigation, draining and/or heating system of a surface, comprising:
- a tank (215) defined by a water-proofing sheath (214) housed in an excavation in the ground;

- a water grid (1, 201) located inside said tank (215) comprising at least one inlet module (2, 202, 502) and at least one outlet module (3, 203, 503);

- an outer water reservoir (380, 480, 501);

- one or more inlet (260) and outlet (261) connections connecting said water grid (1, 201) to said outer water reservoir (380, 480, 501) ;

- a draining soil to fill said tank;
characterized in that each of said at least two modules comprises an impermeable main pipe (4, 204) from which a series of permeable conduits (5, 205) emerge, where said conduits lie on the same horizontal plane of said main pipe.
The system according to claim 1, where said at least two modules (2, 202, 3, 203), assembled to produce said water grid (1, 201), are parallel and mutually opposite: said main pipes (4, 204) have an open end (7) and the opposite end (8) is closed, and they are arranged mutually parallel in said water grid (1, 201) and with said open ends (7) in a diametrically opposite position, and said conduits (5, 205) emerging from an inlet module (2, 202) are located in the available spaces between the conduits (5, 205) emerging from an outlet module (3, 203).
The system according to one of the claims 1 or 2, where said modules (202, 203) assembled to produce said water grid (201) lie on a single horizontal plane, and said conduits (205) are substantially mutually parallel and perpendicular to said main pipes (204).
The system according to one of the claims 1 to 3, where, on the side walls of said tank (215), there is at least an outlet (221) of at least one overflow conduit (222) at a level of said overflow level (213).
The system according to one of the claims 1 to 4, where said draining soil is preferably gravel, where, in said soil, the following stratigraphy can be observed: a water-submersed gravel layer (218), where said water is referred to as culture water, and a dry gravel layer (219) on top of said gravel layer (218), where said water grid (201) is contained in said gravel layer (218) immersed in culture water and said overflow level (213) separates the gravel layer (218) from the dry gravel layer (219).
The system according to one of the claims 1 to 5, where said draining soil has the following stratigraphy, from bottom up:
- optionally, on the bottom of said tank (215), in direct contact with said water-proofing sheath (214), clay clods and/or clay soil;

- optionally, a sand layer (216);

- optionally, a fabric (217);

- a gravel layer (218);

- a dry gravel layer (219);

- optionally, a fabric (221);

- a cultural soil (220).
The system according to one of the claims 1 to 6, where said inlet (2, 202) and outlet (3, 203) modules are made of PVC, and said main pipes (4, 204) have a diameter ranging between 150 and 250 mm and said conduits (5, 205) have a diameter ranging between 60 and 100 mm.
The system according to claim 1, where said outer water reservoir (380, 480) is a reservoir comprising an outer case (385) containing therein a structure (386) that follows the side profile thereof, creating a hollow space (381, 481) between the side walls of said case (385) and the walls of said structure (386), where said hollow space (381, 481) contains coils (382, 482) where hot water circulates in said coils (382, 482), referred to as technical hot water, provided by a thermal plant and at least one outlet conduit (361, 461) coming from the at least one outlet module (205) of the water grid (201) reaches said hollow space (381, 481), where it ends with an open end; a pump (383, 483) is located on the bottom of said outer case (385, 485), which is connected to at least one inlet conduit (360, 460) exiting said outer water reservoir to connect to the open end (7, 207) of said at least one inlet module (2, 202) in said water grid (1, 201).
The system according to claim 8, where, in said thermal plant, said technical water is heated by renewable energy sources, preferably one or more thermal insulation coatings and/or one or more solar panels, preferably associated to at least one thermal well.
The system according to one of the claims 1 to 9, where said culture water is introduced in said water grid at a temperature of about 35° C.
A playground heated with the system of one of the claims 1 to 10.
An industrial warehouse characterized in that a system in accordance with one of the claims 1 to 11 is arranged under the floor of said warehouse, where, above said draining soil, a reinforced concrete pour is arranged, which is the floor of said warehouse.
A method for heating an agricultural and/or industrial and/or sport surface, comprising:
- arranging an excavation in the ground;

- coating said excavation with a water-proofing sheath to create a tank, arranging overflow openings on the side walls of said tank;

- locating inside said tank, in a lower position with respect to said overflow openings, a water grid comprising at least two modules, an inlet module and an outlet module, where each module comprises an impermeable main pipe from which a series of permeable conduits branch, which lie on the same plane of said main pipe;

- filling said tank with a draining soil;

- optionally, arranging a concrete pour on top of said draining soil.