FR3076686A1 - THERMAL REGULATING DEVICE FOR AGRICULTURAL STRUCTURE AND AGRICULTURAL STRUCTURE COMPRISING SUCH A THERMAL CONTROL DEVICE - Google Patents

Abstract

The present invention relates to a thermal regulation device (100) for agricultural structure (1), said thermal regulation device (100) comprising at least one circulation circuit (110) for a heat transfer fluid between at least one storage device ( 120) and at least one heat exchanger (130) traversed by an air flow (300) directed inwardly of the agricultural structure (1) and generated by a fan (131), the at least one heat exchanger (130) comprising: a bundle of tubes (132) inside which the coolant circulates and between which the air flow (300) passes, a cone (134) for guiding the flow of air disposed upstream or downstream of a tube bundle (132), the cone (134) including in particular a small mouth at which the fan (131) is arranged and a large mouth at which the bundle of tubes is arranged (132).

Description

Thermal regulation device for agricultural structure and agricultural structure comprising such a thermal regulation device

The present invention relates to a thermal regulation device for an agricultural structure. More particularly, the invention applies to the regulation and distribution of the temperature within the agricultural structure, by means of storage and controlled release of heat.

In an agricultural structure, for example such as an agricultural greenhouse, in order to be able to grow plants, it is necessary to bring light and heat to the plants in appropriate proportions. In fact, plants have optimal growth in a limited range of temperatures which it is important to respect in order to have an optimal yield within the greenhouse. Day / night cycles also have a significant impact on the temperature within the agricultural structure with an increase in temperature during the day due to solar radiation and a significant drop in temperature at night due to heat dissipation. . In addition, within the agricultural greenhouse, there is a stratification of the air temperature with hot air above and cooler air below.

To reduce temperature differences, especially during the day / night cycle, it is thus known to provide an agricultural greenhouse with a thermal regulation device comprising a circulation circuit of a heat transfer fluid between heat storage devices and exchangers. of heat crossed by an air flow. This thermal regulation device makes it possible to store heat when the temperature within the agricultural greenhouse is high or directly from solar radiation. When the temperature decreases, for example at night or when the luminosity decreases, the heat is restored for example through heat exchangers or passively.

However, this kind of thermal regulation device may not be sufficient to compensate for the temperature variations during the day / night cycle within the agricultural greenhouse and maintain the agricultural greenhouse in the desired temperature range, in particular at night.

In order to solve this problem, it is also known to provide the agricultural greenhouse with a heating system. However, such systems are energy consuming and expensive.

One of the aims of the present invention is therefore to at least partially resolve the drawbacks of the prior art and to propose a device for thermal regulation of an improved agricultural structure.

The present invention therefore relates to a thermal regulation device for an agricultural structure, said thermal regulation device comprising at least one circuit for circulation of a heat transfer fluid between at least one heat storage device and at least one heat exchanger through which a air flow directed towards the interior of the agricultural structure and generated by a fan, the at least one heat exchanger comprising:

° a bundle of tubes inside which the heat transfer fluid circulates and between which the air flow passes, ° a cone for guiding the air flow disposed upstream or downstream of the bundle of tubes, the cone notably comprising a small mouth at the level of which the fan is arranged and a large mouth at the level of which is arranged the bundle of tubes.

According to one aspect of the invention, the agricultural structure comprises at least one roof panel and at least one translucent side walls, the heat exchanger being arranged under the ridge of the agricultural structure, between said ridge and a distance from the order of 1 m below a gutter in the agricultural structure or under a heat shield placed under said ridge 2.

According to another aspect of the invention, the agricultural structure comprises at least two heat exchangers arranged on the same side wall of the agricultural structure.

According to another aspect of the invention, the agricultural structure comprises at least two heat exchangers arranged opposite one another on two side walls of the agricultural structure.

According to another aspect of the invention, the at least one heat storage device is a storage tank for the above-ground heat transfer fluid and disposed vertically above at least one heat exchanger.

According to another aspect of the invention, the thermal regulation device comprises overhead tubes inside which the heat transfer fluid can circulate.

According to another aspect of the invention, the at least one heat storage device comprises buried tubes inside which the heat transfer fluid can circulate.

According to another aspect of the invention, the buried storage tubes are arranged at a depth less than or equal to that of the phase opposition zone.

According to another aspect of the invention, the thermal regulation device is configured to absorb heat energy from the air flow passing through the at least one heat exchanger when the air temperature within the agricultural structure is higher than a first target temperature and release heat energy by thermal diffusion when the air temperature within the agricultural structure is lower than a second target temperature, said second target temperature being lower than the first target temperature.

According to another aspect of the invention, the at least one heat exchanger comprises an air flow redirection nozzle disposed at the outlet of the cone, said redirection nozzle being oriented so as to redirect the air flow towards the ground.

According to another aspect of the invention, the thermal regulation device is configured to absorb heat energy from the air flow passing through the at least one heat exchanger when the air temperature within the agricultural structure is higher than a first target temperature and release heat energy into the air flow passing through the at least one heat exchanger when the air temperature within the agricultural structure is lower than a second target temperature, said second target temperature being lower than the first target temperature.

The present invention also relates to an agricultural structure comprising a thermal regulation device as described above.

Other characteristics and advantages of the invention will appear more clearly on reading the following description, given by way of illustrative and nonlimiting example, and of the appended drawings among which:

• the figure shows a schematic representation in section and front view of an agricultural structure comprising a thermal regulation device according to a first embodiment, • the figure lb shows a schematic representation in section and top view of the agricultural structure of Figure la, • Figure 2a shows a schematic exploded perspective view of a heat exchanger of the thermal control device of Figures la and lb, • Figure 2b shows a schematic perspective view of a heat exchanger of thermal regulation device of FIGS. 1a and 1b, • FIGS. 3 and 4 show simulations of the speed of an air flow within the agricultural structure of FIGS. 1a and 1b, • FIGS. 5 and 6 show simulations of air temperature within the agricultural structure of Figures la and lb, • Figure 7 shows a schematic sectional view and front view of an agricultural structure comprising a thermal regulation device according to a second embodiment, • Figure 8a shows a schematic sectional view and front view of an agricultural structure comprising a thermal regulation device according to a third embodiment, • the Figure 8b shows a schematic sectional view and top view of the agricultural structure of Figure 8a, • Figure 9 shows a schematic perspective view of a heat exchanger of the thermal regulation device of Figures 7 to 8b.

In the various figures, identical elements have the same reference numbers.

The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the characteristics apply only to a single embodiment. Simple features of different embodiments can also be combined and / or interchanged to provide other embodiments.

In the present description, it is possible to index certain elements or parameters, such as for example first element or second element as well as first parameter and second parameter or even first criterion and second criterion etc. In this case, it is a simple indexing to differentiate and name elements or parameters or criteria that are similar but not identical. This indexing does not imply a priority of an element, parameter or criterion over another and one can easily interchange such names without departing from the scope of this description.

This indexing does not imply an order in time for example to assess this or that criterion.

Figures la and lb show schematic sectional representations of an agricultural structure 1 according to a first embodiment, more precisely of an agricultural greenhouse, respectively in side view and in top view. An XYZ trihedron is shown in the figures to help understand the different orientations. The X axis can thus correspond to the width of the agricultural structure 1. The Y axis can correspond to the height of the agricultural structure 1 and the Z axis to its length.

By agricultural structure 1 is meant here a structure inside which an agricultural activity can be carried out. The agricultural term is used here in a broad sense and includes as well activities of culture of plants for example of market gardening, in agricultural greenhouse, or then activities of breeding, for example avian in a covered henhouse.

In the remainder of this description, the invention is described in connection with a cultivation of plants as cultivated products without this being considered to be restrictive.

In the context of an agricultural greenhouse as illustrated in FIGS. 1 a and 1 b, cultivated products 7 can in particular be placed on a cultivation surface 5 which can be placed directly on the ground or else raised above the ground level, for example when 'these are culture tablets.

The agricultural greenhouse can thus be an elongated structure, preferably closed and mainly intended for agricultural production. The agricultural greenhouse comprises at least one roof panel 2 and at least one of its side walls 3 is translucent in order to let the solar radiation through. Generally the agricultural greenhouse comprises a framework, for example metallic or wooden, and roofing elements such as a tarpaulin made of plastic material or glass panels. The roof 2 of the agricultural structure 1 is maintained by a frame called ridge which can have a triangular shape as in Figures la and 7a, rounded or pointed. The agricultural greenhouse may also include one or more heat shields (not shown) arranged under the ridge 2.

The agricultural structure 1 comprises a thermal regulation device 100. This thermal regulation device 100 makes it possible in particular to regulate the temperature within the agricultural structure 1, in particular during the day / night cycle. For this, the thermal regulation device 100 comprises at least one circulation circuit 110 of a heat transfer fluid between at least one heat storage device 120 and at least one heat exchanger 130 through which an air flow 300. This air flow 300 is more particularly directed towards the interior of the agricultural structure 1 and generated by a fan 131 (visible in FIGS. 2a, 2b and 8). The heat transfer fluid, for example water, can in particular be set in motion in the thermal regulation device 100 by means of a pump (not shown).

According to this first embodiment, the at least one heat storage device 120 may be a storage tank for the above-ground heat transfer fluid and disposed vertically above at least one heat exchanger 130. The fact that the storage device (s) 120 are arranged directly above at least one heat exchanger 130 makes it possible to limit the pressure drops during the circulation of the heat transfer fluid. Several heat exchangers 130 can be connected to the same storage device 120, as illustrated in FIG. 1b. However, it is entirely possible to imagine a case in which each heat exchanger 130 is connected to a separate heat device 130.

The at least one heat exchanger 130 is preferably placed under the ridge 2 of the agricultural structure 1, between said ridge 2 and a distance of the order of 1 m below a gutter of the agricultural structure 1 or else below the heat shield (s). The at least one heat exchanger 130 is also preferably disposed near one of the side walls 3 of the agricultural structure 1. In the context of an agricultural greenhouse, this positioning makes it possible to recover heat energy during the day at the level of the translucent side walls 3 and of the ridge 2. In the context of a chicken coop for example, this makes it possible to recover the latent heat, generated by animal activity and solar radiation, which tends to accumulate in the upper part of the structure.

Thus, as shown in FIG. 1 a, the agricultural structure 1 can comprise at least two heat exchangers 130 arranged opposite one another on two side walls 3 of the agricultural structure 1. This is particularly the case when these two side walls are translucent and can be exposed to solar radiation. Such a configuration can also be advantageous when the agricultural structure 1 has a width, along the axis X, greater than the blowing range of the heat exchangers 130. In this case, the thermal regulation device 100 can include devices storage 120 directly above the heat exchangers 130 at the two side walls 3, as shown in Figures la and lb.

However, it is entirely possible to imagine an embodiment where the agricultural structure 1 only has one or more heat exchangers 130 at only one of its side walls 3.

As shown in FIG. 1b, along its length, that is to say along the axis Z, the agricultural structure 1 can comprise at least two heat exchangers 130 arranged at the same side wall 3. The fact having several heat exchangers 130 distributed over the length of the agricultural structure 1 makes it possible to be able to blow the air flow 300 over a large part of the length of the agricultural structure. So that this air flow 300 is distributed over the entire length of the agricultural structure 1, the heat exchangers 130 can in particular be arranged along the axis Z at a distance from one another between 3 and 9 times their width. This makes it possible to have a compromise between the number of heat exchangers 130 necessary for the length of the agricultural structure 1, their heat exchange potential and the energy consumption necessary to operate the thermal regulation device 100.

The air flow 300 is oriented along the X axis and directed towards the center of the agricultural structure 1.

As shown in FIGS. 2a and 2b, a heat exchanger 130 can include:

• a bundle of tubes 132 inside which the heat transfer fluid circulates and between which the air flow 300 passes. The heat transfer fluid circulates in particular within the bundle of tubes 132 between a fluid inlet 133a and a fluid outlet 133b .

• a cone 134 for guiding the air flow 300 arranged here downstream of the bundle of tubes 132 in the direction of circulation of the air flow 300. This cone 134 comprises in particular a small mouth at the level of which the fan 131 is disposed and a large mouth at which the bundle of tubes 132 is arranged.

The fan 131 is more particularly arranged at the smallest mouth of the cone 134 in order to be as small as possible and therefore the least energy-consuming.

The thermal regulation device 100 according to this first embodiment is in particular configured to absorb heat energy from the air flow passing through the at least one heat exchanger 130 when the temperature of the air within the agricultural structure 1 is higher than a first target temperature, for example during the day. During this absorption of heat energy, the cone 134 acts as a concentrator and allows the use of a fan 131 of smaller dimension than that of the bundle of tubes 132 and therefore to have a lower electrical consumption in order to generating the air flow 300 over the entire exchange surface of the heat exchanger 130. Due to this lower energy consumption, the coefficient of performance of the thermal regulation device 100 is optimized and therefore better. This absorption of heat energy makes it possible to cool the air flow 300 and thus limit the increase in temperature within the agricultural structure 1. In addition, this absorption of heat energy can make it possible to dehumidify the air flow 300 and thus to regulate the hygrometry of the agricultural structure. Indeed, during the day, due to the evapotranspiration of plants or the perspiration and respiration of animals, this humidity tends to increase. Water condenses while level of the heat exchanger 130 during the absorption of heat energy and this water can even be recovered for later use.

When the air temperature within the agricultural structure 1 is lower than a second target temperature, lower than the first target temperature, for example at night, the thermal regulation device 100 releases heat energy into the flow d air 300 passing through at least one heat exchanger 130. Just as during the absorption of heat energy, during the return of heat energy, the cone

134 plays the role of concentrator and allows the use of a fan 131 of smaller dimension than that of the bundle of tubes 132 and therefore having a lower electrical consumption in order to generate the air flow 300 over the entire surface of exchange of the heat exchanger 130.

The heat exchanger 130 may also include a redirection nozzle

135 of the air flow 300. This redirection nozzle 135 is in particular disposed at the outlet of the cone 134 and is oriented so as to redirect the air flow 300 towards the ground, more precisely in this case towards the cultivation surfaces 5 .

This redirection nozzle 135 is in particular oriented so as to redirect the air flow 300 towards the culture surfaces 5 with an angle of between 10 and 25 degrees.

This allows, during the return of heat, to redirect the flow of hot air 300 directly to the ground and therefore for example to the culture surfaces 5 and thus limit the drop in temperature to this level. In addition, the redirection nozzle 135 allows homogenization of the air temperature in the agricultural structure 1. The redirection nozzle 135 also makes it possible, in relation to the fan 131, to project the air flow 300 far enough, for example at a range of more than 15 m, in order to regulate the temperature over the entire surface of the agricultural structure 1.

Figures 3 and 4 show schematic representations of the amplitude of the air speed within the agricultural structure 1 during the operation of the thermal regulation device 100, more particularly during the day when the thermal regulation device 100 absorbs the heat energy of the air flow 300. Figure 3 shows the amplitude of the air speed along a section plane along the plane formed by the X and Y axes. Figure 4 shows the amplitude of the air speed along a cutting plane along the plane formed by the X and Z axes at a height of 1 m above the culture surfaces 5.

Zone A corresponds to an amplitude of the speed between 0 and 0.1 m / s.

Zone B corresponds to an amplitude of the speed between 0.1 and 0.2 m / s.

Zone C corresponds to an amplitude of the speed between 0.2 and 0.3 m / s.

Zone D corresponds to an amplitude of the speed between 0.3 and 0.4 m / s.

Zone E corresponds to an amplitude of the speed between 0.4 and 0.5 m / s.

Figures 5 and 6 show schematic representations of the air temperature within the agricultural structure 1 during the operation of the thermal regulation device 100, more particularly during the day when the thermal regulation device 100 absorbs heat energy of the air flow 300. FIG. 5 shows the temperature of the air along a sectional plane along the plane formed by the axes X and Y. FIG. 6 shows the temperature of the air according to a cutting plane along the plane formed by the X and Z axes at a height of 1 m above the crop surfaces 5.

In FIGS. 3 to 6, the results are expressed for heat exchangers 130 having a bundle of tubes 132 of the order of 0.8 m × 1 m in cross section and a depth of the order of 35 cm. The cone 134 has a length of around 50 cm with a nozzle outlet diameter 135 of around 45 cm. The nozzle 135 has a length of about 50 cm. The fan 131 allows an average blowing speed of the order of 4.26 m / s at the outlet of the nozzle 135 and an air return speed (that is to say at the inlet of the tube bundle 132) of the order of 1 m / s. The blowing range is between 9 and 15 m and the residual speed of the air flow 300 at a distance of 6 m is around 0.85 ± 0.1 m / s.

These Figures 3 to 6 thus show the formation of the air flow 300 as well as the fact that this air flow 300 is directed towards the culture surfaces 5. In addition, these Figures 3 to 6 show that the thermal regulation device 100 allows good redistribution and good homogenization of the air temperature, in particular due to the presence of redirection nozzles 135.

According to a second embodiment, illustrated in FIG. 7, the at least one storage device 120 can also be a reservoir like the first embodiment. However, the thermal regulation device 10 comprises overhead tubes 123 arranged for example along the culture surfaces 5, and inside which the heat transfer fluid can circulate.

Figures 8a and 8b show a thermal regulation device 100 according to a third embodiment. This third embodiment differs from the first embodiment in that the at least one storage device 120 comprises buried tubes 122 inside which the heat transfer fluid can circulate. These buried tubes 122 are in particular arranged at a depth of between 30 and 100 cm under the cultivation surfaces 5. The buried tubes 122 make it possible to store heat energy in the soil.

When the buried tubes 122 are for example arranged at a depth less than or equal to the zone of phase opposition of the ground, that is to say the zone below which the temperature of the ground varies little or not between example of the 12-hour phases or day / night phases and above which the ground temperature varies under the influence of these phases. The depth of this phase opposition zone varies depending on the nature of the soil and its physical characteristics such as its moisture. The depth of this phase opposition zone also varies depending on the duration of the phases. This phase opposition zone can for example be between 30 and 45 cm, preferably 40 cm, for a soil composed of earth and 12-hour phases.

When the buried tubes 122 are for example arranged at a depth greater than that of the phase opposition zone, for example at a depth of between 45 and 100 cm, preferably 80 m, the ground is no longer able to restore the heat stored by thermal diffusion and the restitution must be carried out by means of at least one heat exchanger 130.

The thermal regulation device 100 according to these second and third embodiments can thus be in particular configured to absorb heat energy from the air flow passing through the at least one heat exchanger 130 when the temperature of the air within of the agricultural structure 1 is higher than a first target temperature, for example during the day. During this absorption of heat energy, as for the first embodiment, the cone 134 acts as a concentrator and allows, by means of a fan of smaller dimension than that of the bundle of tubes 132 and therefore to have a lower power consumption, generation of air flow 300 over the entire exchange surface. Because of this lower energy consumption, the coefficient of performance of the thermal regulation device 100 is optimized and therefore better.

When the air temperature within the agricultural structure 1 is lower than a second target temperature, lower than the first target temperature, for example at night, the thermal regulation device 100 releases heat energy by thermal diffusion at ground or overhead level 123.

When the tubes 132 are buried at a depth less than or equal to the phase opposition zone, or when the thermal regulation device 100 comprises overhead tubes 123, these second and third embodiments may also differ from the first embodiment by the fact that the heat exchanger 130 does not have a redirection nozzle 135, as shown in FIG. 9. The air flow 300 at the outlet of the heat exchangers 130 may then not be directed towards the culture surfaces 5 Indeed, because the heat energy is restored by thermal diffusion whatsoever, the presence of the redirection nozzles 135 has little or no impact. When the heat exchanger 130 does not have a redirection nozzle 135, the latter can only be used during the absorption of heat energy. The cone 134 can thus be placed downstream of the bundle of tubes 132 in the direction of circulation of the air flow 300, as described above. According to a particular embodiment (not shown), the cone 134 can be placed upstream of the bundle of tubes 132 in the direction of circulation of the air flow 300.

Thus, it is clear that the thermal regulation device 100 makes it possible to regulate the temperature of an agricultural structure 1 by absorbing heat energy on the 10th day and by restoring this heat energy at night. Due to the presence of a cone 134 at the level of the heat exchanger 130 makes it possible to improve the heat exchanges and to improve the coefficient of performance of the thermal regulation device 100. The cone 134 allows in particular better absorption of heat energy and reduced power consumption of the fan 131.

Claims (12)

1. A thermal regulation device (100) for an agricultural structure (1), said thermal regulation device (100) comprising at least one circulation circuit (110) of a heat transfer fluid between at least one storage device (120) of heat and at least one heat exchanger (130) through which an air flow (300) directed towards the interior of the agricultural structure (1) and generated by a fan (131), characterized in that the at least a heat exchanger (130) comprises: ° a bundle of tubes (132) inside which the heat transfer fluid circulates and between which the air flow (300) passes, ° a cone (134) for guiding the air flow disposed upstream or downstream of the bundle of tubes (132), the cone (134) comprising in particular a small mouth at the level of which the fan (131) is arranged and a large mouth at the level of which is the bundle of tubes (132). 2. Thermal regulation device (100) according to one of the preceding claims, characterized in that the agricultural structure (1) comprises at least one roof panel (2) and at least one translucent side walls (3), the heat exchanger (130) being disposed under the ridge (2) of the agricultural structure (1), between said ridge (2) and a distance of the order of 1 m below a gutter of the agricultural structure ( 1) or a distance of 1 m below a heat shield placed under said ridge (2). 3. A thermal regulation device (100) according to one of the preceding claims, characterized in that the agricultural structure (1) comprises at least two heat exchangers (130) arranged on the same side wall (3) of the agricultural structure (1). 4. Thermal regulation device (100) according to one of the preceding claims, characterized in that the agricultural structure (1) comprises at least two heat exchangers (130) arranged opposite one another on two walls side (3) of the agricultural structure (1). 5. A thermal regulation device (100) according to one of claims 1 to 4, characterized in that the at least one heat storage device (120) is a storage tank for the above-ground heat transfer fluid and disposed at plumb with at least one heat exchanger (130). 6. A thermal regulation device (100) according to the preceding claim, characterized in that it comprises overhead tubes (123) inside which the heat transfer fluid can circulate. 7. thermal regulation device (100) according to one of claims 1 to 4, characterized in that the at least one heat storage device (120) comprises buried tubes (122) inside which can circulate the heat transfer fluid. 8. A thermal regulation device (100) according to the preceding claim, characterized in that the buried storage tubes (122) are arranged at a depth less than or equal to that of the phase opposition zone. 9. A thermal regulation device (100) according to any one of claims 6 or 8, characterized in that it is configured to absorb heat energy from the air flow passing through the at least one heat exchanger ( 130) when the air temperature within the agricultural structure (1) is higher than a first target temperature and release heat energy by thermal diffusion when the air temperature within the agricultural structure (1 ) is lower than a second target temperature, said second target temperature lower than the first target temperature. 10. A thermal regulation device (100) according to one of claims 1 to 6, characterized in that the at least one heat exchanger (130) comprises a redirection nozzle (135) of the air flow disposed at the outlet. of the cone (134), said redirection nozzle (135) being oriented so as to redirect the air flow towards the ground. 11. A thermal regulation device (100) according to the preceding claim, characterized in that it is configured to absorb heat energy from the air flow passing through the at least one heat exchanger (130) when the temperature of the air within the agricultural structure (1) is above a first target temperature and release heat energy into the air flow passing through the at least one heat exchanger (130) when the temperature of the air within the agricultural structure (1) is lower than a second target temperature, said second target temperature lower than the first target temperature. 12. Agricultural structure (1) characterized in that it comprises a thermal regulation device (100) according to one of the preceding claims.