WO2007057594A1

WO2007057594A1 - Method of monitoring the storage of heat energy in the ground and associated device

Info

Publication number: WO2007057594A1
Application number: PCT/FR2006/051148
Authority: WO
Inventors: Bruno Seguin; Christophe Reiss
Original assignee: Ventilone
Priority date: 2005-11-10
Filing date: 2006-11-07
Publication date: 2007-05-24
Also published as: CA2629234A1; US20080230205A1; FR2893123A1; FR2893123B1; EP1946009A1

Abstract

The invention relates to a method of monitoring a unit for storing heat energy in the ground, including a plurality of heat exchangers which are buried in the ground. According to the invention, each of the aforementioned heat exchangers enables an exchange of heat energy between a heat-transfer fluid passing therethrough and the ground. The energy storage unit is disposed at the interface between a heat energy source and a heat energy consumer in order to store heat energy. The inventive method is characterised in that it consists in measuring: the temperature at different points of the ground using buried temperature sensors, the temperatures and flow rate of a heat-transfer fluid entering and leaving the source in order to determine the thermal output supplied by the source, and the temperatures and flow rate of a heat-transfer fluid entering and leaving the consumer in order to determine the thermal output to be supplied to the consumer. The invention is also characterised in that the storage of heat energy in the storage unit is optimised by selecting active exchangers from among the plurality of exchangers as a function of the temperature measurements, the flow rate measurements and the thermal output measurements.

Description

Method for controlling the storage of thermal energy in the soil and associated device

The invention relates to the storage of heat energy in the soil. More particularly, the subject of the invention is that of thermal energy storage for decoupling a heat source and / or a cold consumer, on the one hand, from a heat consumer and / or a cold source, from somewhere else.

In energy systems using thermal energy in the form of heat, such as building heating systems or industrial heating processes, or in the form of cold, such as building air conditioning or industrial refrigeration, the production of Thermal energy is usually synchronized with its consumption.

Due mainly to the rising cost of energy, the efficiency of this kind of synchronized system is an essential aspect, which can only be improved through the optimization of the production system.

(efficiency improvement) or consumption system

(minimizing the energy consumed).

Another way to improve energy systems economically is to decouple production and consumption using thermal energy storage systems. This decoupling then makes it possible to produce the energy needed not only for the periods of consumption, but at times when energy is available at low cost.

Advantageously, the generalization of such heat storage systems would also allow the recovery and exploitation of a large part of the industrial thermal energy, nowadays massively unused mainly because of the shift of its production with periods of consumption.

Finally, thermal energy storage systems are very well adapted to the exploitation of renewable energies, which are often characterized by their intermittency, and whose availability does not always coincide with consumption, especially in the case of energy. solar thermal energy. Heat energy storage devices are known that use the sensible heat of a storage material, that is to say the energy stored by this material when it undergoes a variation of temperature, without any change of phase. and without change of chemical composition, and wherein the storage material used is none other than the soil. In what follows, the term soil must be understood in the broad sense and covers both natural soil such as a volume of soil, a stratum of rock, a developed ground such as the basement of a building or the basement of a parking area, the foundations of a building and their geological environment, elements and assemblies of structural elements of a building (walls, slabs ...), or the equivalent. Optionally, the soil is not homogeneous and comprises different structures and materials having varied thermodynamic properties. Energy exchanges between the storage material on the one hand, and the sources and consumers of energy on the other hand, are ensured by the circulation of at least one heat transfer fluid inside the pipes.

An important parameter to take into account to describe these devices is the time scale on which is performed the accumulation and then the use of the stored heat energy. For example, a district heating device for heating a residential area must have a seasonal operating cycle: in summer, the heat energy produced by a heat source such as a solar collector, or cold consumer as an air conditioning device; in winter, this heat energy is released to heat homes as a heat consumer.

This type of storage devices operating with a significant time scale, of the order of a few months to a year, presents a specific problem.

One of the main problems limiting the efficiency of heat energy storage is significant heat loss. These losses, essentially of the diffusive type, are due to the thermal conduction between an energy storage zone having an average temperature T and what could be called an external zone remained at a temperature TO. This is all the more marked as, for example in the case of energy storage in the soil, the storage material may not be physically bounded: the storage material may be a continuous medium. There is therefore no physical delimitation between the storage area and the outdoor area. This embodiment is particularly advantageous since it makes it possible to avoid the excavation of a large volume of soil, a necessary step when it is desired to delimit a storage area, for example in the form of a concrete block buried in the floor, or more simply a formwork.

An important aspect to consider when planning such a thermal storage system is the presence on the site of potential underground hydrogeological flows. These movements of water or moisture in the basement have the effect of moving the stored heat out of the storage area, thus causing consequent heat loss. These transverse flows thus reduce the efficiency of the storage unit, when they do not simply prevent its realization.

In addition, the volume of storage material required for a given application is an important parameter affecting the cost of the installation. This volume depends directly on the difference between the average temperature of the storage area at the end of the charging cycle, when the storage area is in its "charged" state, and the same temperature at the end of the discharge cycle, when the storage area is in its "unloaded" state. The smaller the difference, the larger the volume needed to store a given amount of energy. The dilemma is then: increasing the temperature variation of the storage area over one cycle reduces the volume needed, thus reducing the cost of construction, but in return increases the difference between the temperature of this storage area and the temperature of the storage area. natural temperature of the soil, thus increasing heat losses. Conversely, changing the average temperature of the storage area on a cycle between two temperature levels close to each other (and close to the natural temperature of the soil) will reduce boundary losses, but will require a volume, and therefore a higher construction cost. The invention therefore aims to solve the problems mentioned above.

For this purpose, the subject of the invention is a method of controlling a thermal energy storage unit in the ground comprising a plurality of heat exchangers buried in the ground, each of said exchangers permitting an exchange of heat energy between a heat exchanger heat transfer fluid therethrough and the ground, said energy storage unit being disposed at the interface between a source and a consumer of heat energy for storing thermal energy, characterized in that the temperature is measured by different points of the ground by means of buried temperature sensors, the temperatures and flow rate of a heat transfer fluid at the inlet and at the outlet of the source to determine the thermal power supplied by the source, and the temperatures and flow rate of a heat transfer fluid in input and output of the consumer to determine the thermal power to be supplied to the consumer, and in that the thermal energy storage is optimized in said storage unit by selecting active exchangers from said plurality of exchangers based on temperature measurements, flow measurements and thermal power measurements. The heat energy source is defined as one or more elements providing heat to the system via a heat transfer fluid. The consumer of heat energy is defined as one or more elements absorbing heat to the system via a heat transfer fluid. Preferably, the method comprises the steps of previously determining an optimum map of the temperatures in the soil; determining an instantaneous map of the temperatures in the soil by means of said temperature measurements made at different points of the ground; selecting active exchangers from said set of exchangers as a function of the local temperature differences between said instantaneous card and said optimal card, temperatures and flow rate of the heat transfer fluid at the input and output of the source, and temperatures and flow rate of the coolant in input and output of the consumer.

Thus, one can converge the state of the storage area in the current state to the optimal state taking into account the constraints related to the contribution of the source and the needs of the consumer. The various steps can be repeated over time as many times as necessary in order to achieve a chronological sequence of optimal states of the storage area tending to maximize the energy efficiency of the process according to the invention, while satisfying the constraints induced by the versatility and asynchronism of the source and the consumer.

Preferably, an exchanger is activated in extraction to locally extract heat energy from the soil or injection to locally inject heat energy into the soil.

More preferably, an exchanger is activated by selecting the direction of flow and the flow of said heat transfer fluid therethrough. According to a mode of operation, when the thermal power supplied by the source is adapted to the thermal power used by the consumer, none of the heat exchangers is activated and the heat transfer fluid is circulated between a loop comprising the source and a loop. involving the consumer.

In another mode of operation, when the thermal power supplied by the source is not usable by the consumer, the heat transfer fluid is circulated between a loop comprising the source and a loop comprising injectable exchangers, and the the heat transfer fluid is circulated simultaneously between a loop comprising the consumer and a loop comprising exchangers activated for extraction. According to one operating mode, heat is moved inside the storage unit by circulating the coolant between a loop comprising at least one extraction-activated exchanger and a loop comprising at least one activated exchanger for injection. .

According to a mode of operation, when the thermal power supplied by the source is greater than the thermal power used by the consumer, the heat transfer fluid is circulated on the one hand in a loop comprising the source and on the other hand in a loop comprising the consumer and a loop comprising exchangers activated by injection. According to one mode of operation, the thermal power used by the consumer being zero, the thermal power supplied by the source is totally injected into the storage unit.

According to one mode of operation, the thermal power supplied by the source being lower than the thermal power used by the consumer, the coolant is circulated on the one hand in a loop comprising the consumer and on the other hand in a loop comprising the source and a loop comprising exchangers activated in extraction. According to yet another mode of operation, when the thermal power supplied by the source is zero, the thermal power used by the consumer is completely extracted from the storage unit.

The invention also relates to a hydronic control system of a thermal energy storage unit in the soil comprising a plurality of heat exchangers buried in the ground, each of said exchangers allowing a heat energy exchange between a heat transfer fluid therethrough and the ground, said hydronic system being intended to be disposed between a source of heat energy, a consumer of thermal energy and said storage unit, characterized in that it comprises: a plurality of temperature sensors buried in the ground; temperature and flow rate sensors for measuring the thermal power supplied by the source and the thermal power used by the consumer; grouping means for grouping said exchangers into a plurality of elementary exchange units, an exchange unit comprising at least one exchanger; and, activation means for selectively activating said elementary exchange units.

Preferably, an exchanger comprising a hot end and a cold end, the grouping means can form groups of exchangers as exchange unit, the different hot ends of said exchangers of the same group being connected to a hot collector and the cold ends of these same exchangers being connected to a cold collector, the different exchangers of said group being in parallel with each other. More preferably, said grouping means make it possible to form series of exchangers as exchange unit, a series of exchangers comprising a number of groups of exchangers, the cold collector of one of said groups of one series being connected to the hot collector of the next group of said series, so that said groups of the same series of exchangers are arranged in series between an initial group and a final group.

In one embodiment, said grouping means comprise first and second switches, each switch having a main line and secondary lines, the hot collector of a group of heat exchangers being connected to the first switch via a secondary line of this one. equipped with a shut-off valve, and the cold collector of the exchanger group being connected to the second switch via a secondary pipe thereof provided with a shut-off valve, so that the grouping means make it possible to arbitrarily selecting, at a given time and depending on the position of the valves of the first and second switches, a first group of exchangers and a last group of exchangers, to form between them a branch of exchangers used as a exchange unit.

Preferably, the activation means comprise injection activation means capable of forming a hydraulic injection loop comprising at least one exchange unit for the injection of energy, and suitable extraction activation means. forming a hydraulic extraction loop having at least one exchange unit for energy extraction.

More preferably, said injection activation means comprise an inlet injection branch and an outlet injection branch, each exchange unit being connected by its hot end to said inlet injection branch and by its cold end at said output injection connection to form a connection between the input and output injection connections, the different exchange units then being in parallel with each other between said input injection connections and output, each link thus defined being provided with flow control means in injection, so that the flow rate in said connection considered can be arbitrarily fixed during an injection.

In the presently preferred embodiment, the extraction activation means comprise an input extraction branch and an outlet extraction branch, the exchange units being respectively connected by their cold end to said extraction branch. and at their hot end to said outlet extraction connection, to form a connection between the inlet and outlet extraction connections, the different exchange units then being in parallel with one another between said connections. extraction of inlet and outlet, each link thus defined being provided with extraction rate control means, so that the flow rate in said connection considered can be arbitrarily set during an extraction. It should be noted that the regulating means can apply a zero flow rate to the exchange unit, thus allowing the arbitrary exclusion of the exchange unit during injection or extraction.

More preferably, a differential pressure sensor is connected between said input and output connections, the feed pipe of the inlet connection comprises a differential pressure controlled pump according to the measurement made by said sensor, so that the flow in any of the parallel connections between the input and output connections can be individually controlled.

Preferably, the system is provided with pumping means comprising pumps capable of circulating the coolant in a loop comprising the energy source and / or in a loop comprising the energy consumer.

More preferably, the system is provided with pumping means comprising pumps able to circulate the heat transfer fluid in an injection loop comprising at least one exchange unit operating in energy injection and in an extraction loop comprising at least one exchange unit operating in energy extraction, and connection means allowing at least one connection among the connection of the circulation loop in the source with the injection loop; the connection of the loop of circulation in the consumer with the extraction loop; connecting the circulation loop in the source with the injection loop, and simultaneously, connecting the circulation loop in the consumer with the extraction loop; the connection of the extraction loop with the injection loop; the connection of the circulation loop in the source with the circulation loop in the consumer; the connection of the extraction loop with the injection loop, and simultaneously the connection of the circulation loop in the source with the circulation loop in the consumer. Preferably, the connection means also allow the connection of the circulation loop in the consumer with the extraction loop and the circulation loop in the source; and, connecting the circulation loop in the source with the injection loop and the circulation loop in the consumer. In the embodiment envisaged, the connection means comprise a first pressure-reducing bottle, connected to an expansion vessel forming the neutral point of said hydraulic system, said first pressure-reducing bottle being connected to said extraction loop of a part and to said circulation loop in the consumer on the other hand; a first pair of shutoff valves, the state of which enables said circulation loop in the hot source to be connected to said first pressure bottle; a second pair of stop valves whose state allows the injection loop to be connected to said first pressure bottle. More preferably, the connection means comprise a second pressure-reducing bottle connected to said expansion vessel forming the neutral point of said hydraulic system; a third pair of shut-off valves whose state allows, in relation to the state of said first pair of valves, to connect said circulation loop in the source to said second pressure-reducing bottle, the loop in extraction being connected to said first pressure bottle; a fourth pair of shut-off valves, the state of which, in relation to the state of the second pair of valves, enables said injection loop to be connected to said second pressure-reducing bottle; circulation in the consumer being connected to said first pressure bottle.

The activation, connection and pumping means being automatically operable, the system comprises a calculation unit able to receive measurement signals emitted by the various sensors and to transmit a control signal to said activation means, connection, and pumping.

In the embodiment envisaged, the computing unit executes the instructions of a program stored in storage means of said calculation unit to implement the preceded according to the invention.

The subject of the invention is also a system for storing heat energy in the soil comprising a hydronic system according to the invention and an energy storage unit. Preferably, the plurality of exchangers of the energy storage unit comprises at least ten heat exchangers.

Advantageously, the possibility of actively controlling, throughout the charge / discharge cycle, the temperature distribution inside the storage area makes it possible to optimize the necessary volume of storage material. In fact, the volume of the required storage area depends only on the temperature level at two given instants of the cycle, whereas the thermal losses depend on the integral over the entire heat flow cycle at the limits of the storage area. . By continually monitoring the temperature distribution in the storage area, it is possible to maximize the average temperature difference over the volume between the "loaded" final state and the "discharged" initial state, while maintaining an optimal distribution of temperatures close to the limits of this zone, thus limiting the heat flux to the limits during all the intermediate states of the cycle.

The natural phenomenon of thermal diffusion is amplified by the uncontrolled circulation of the coolant throughout the storage area. For example, during the charging cycle of a heat storage unit from a variable source such as a solar collector, the circulation of a "lukewarm" fluid having a temperature Tf through successively a "hot" zone, having a temperature higher than Tf, then a "cold" zone, having a temperature below Tf, will tend to homogenize the temperature of the two zones, thus accelerating the natural phenomenon of thermal diffusion inside the storage area. The system according to the invention is capable of restricting the circulation of fluid to the only physical zones in adequacy with the desired mode of operation, in particular with the required temperature values of the fluid entering and leaving the storage area. Advantageously, the sources and the consumers being heterogeneous, when at a given moment the source produces a thermal energy unusable by the consumer, in particular because of an inadequate heat transfer fluid temperature, whereas in the prior art it was not not directly stored in the diffusive system but in an additional device for storing the heat transfer fluid itself, this energy is now directly stored for later use. Indeed, the system according to the invention is capable of injecting this energy produced by the source into the storage unit while simultaneously withdrawing energy from this same storage unit to supply the consumer. Since the fluid temperature levels corresponding to the energy injected and the energy drawn off are different, the system selects, as a function of the temperature distribution in the storage zone, the regions that are suitable for injection and the regions that are suitable for racking. The invention will be better understood and other objects, details, features and advantages thereof will appear more clearly in the description given solely for illustrative and not restrictive with reference to the accompanying drawings.

Figure 1 shows, schematically, a heat exchanger of a power storage unit;

FIG. 2 is a general schematic view of the hydronic system according to the invention at the interface between a source, a consumer and an energy storage unit; Figure 3 schematically shows a particular embodiment of the pumping subsystem portion of the hydronic system of Figure 2;

FIG. 4A schematically represents the pumping subsystem operating in energy recycling mode;

FIG. 4B schematically represents the pumping subsystem operating in simultaneous injection and extraction mode;

FIG. 4C schematically represents the pumping subsystem operating in partial energy extraction mode; FIG. 4D schematically represents the pumping subsystem operating in partial energy injection mode;

FIG. 5 schematically represents the flow control subsystem and the connection subsystem of the hydronic system according to the invention; Fig. 6A shows the flow control subsystem in the energy injection mode;

Fig. 6B shows the flow control subsystem in the energy extraction mode;

FIG. 7 is a schematic representation of an alternative embodiment of the hydronic system connection subsystem according to the invention; and,

Figures 8A, B, C and D show successive optimal maps for a heat storage area.

Generally speaking, since a physical system is delimited by a closed surface, the heat energy will be positively counted when it corresponds to a heat flux entering the system and will be counted negatively when it corresponds to a heat flow coming out of the system. .

FIG. 1 diagrammatically shows a simple example of a heat exchanger 5 buried vertically in the ground 2.

According to this example, it is a U-shaped pipe 51 having a "hot" end 53 and a "cold" end 54. The pipe 51 is inserted into a sheath 55 facilitating the exchange of heat between the ground 2 and the coolant circulating in the pipe 51. The exchanger 5 is placed in a well drilled in the ground that can have several tens of depth meters (typically 50 m) and the material constituting the sheath 55 is cast as filler material. The heat transfer fluid is able to flow in the pipe 51 with an adjustable flow, in one direction or in another, ie from the cold end 54 towards the hot end 53 (as indicated by the arrows 56 in FIG. 1), or, conversely, from the hot end to the cold end. In a variant, a sheath 55 could accommodate several pipes 51.

In an operating mode allowing the extraction of heat from the storage material, the exchanger 5 is activated so that the heat transfer fluid at temperature T5L is injected at the cold end 54. T5L is chosen so as to be less than the ground temperature T2 in the vicinity of the exchanger. There is then a transfer of heat from the ground to the fluid and this all along the pipe 51. This is what was represented by the black arrows 57 in FIG. 1. The heat transfer fluid exits at the level of the hot end 53 with a temperature T5H greater than the temperature T5L, but less than or equal to the temperature T2.

In a reverse mode of operation, consisting of locally injecting heat into the ground 2, the exchanger 5 is activated so that the coolant, having a temperature T5H greater than the local temperature of the ground T2, is injected by hot end 53. A heat exchange is then heat transfer fluid to the storage material and this along the pipe 51. The temperature of the coolant at the cold end 54 reaches a T5L lower temperature T5H but greater than or equal to T2.

More generally, the heat exchanger is defined as a device consisting of an arbitrary number of pipes buried in the ground, each pipe being defined by a geometry and a clean material, these pipes being connected arbitrarily but of such that the piping system thus formed has two ends, a "hot" end 53 and a "cold" end 54 (the same borehole can accommodate several heat exchangers).

In the envisaged applications, an energy storage unit is made up of more than 10 such heat exchangers 5. The different exchangers of the energy storage unit can be arranged at different locations. different depths relative to each other and have or not 55 sheaths in common.

The hydronic system 100 according to the invention has been shown diagrammatically in FIG. 2. The hydronic system 100 is at the interface between any type of energy storage unit 30, any type of heat source or consumer of cold 10, defined as one or more elements providing heat to the system via a coolant, and any type of cold source or heat consumer 20, defined as one or more heat-absorbing elements to the system via a heat transfer fluid. In what follows, the source of heat or cold consumer 10 is called "hot source" or simply "source", the consumer of heat or cold source 20 is called "cold source" or simply "consumer". The hydronic system 100 makes it possible to decouple the production by the hot source 10 of a heat energy, positively counted for the hydronic system 100, of the consumption by a cold heat energy source 20, negatively counted for the hydronic system 100, in storing, by means of the energy storage unit 30, thermal energy (heat or cold) in a storage area 31 defined in the ground. It should be remembered that the term soil must be understood in the broad sense and covers both natural soil such as a volume of soil, a stratum of rock, developed soil such as the basement of a building or the subsoil ground of a parking area, the foundations of a building and their geological environment, elements and assemblies of structural elements of a building (walls, slabs ...), or the equivalent. The storage zone 31 corresponds to the zone heated or cooled by all the heat exchangers. It should be noted that, in the case where the energy is stored in a continuous medium, for example earth, the storage area is not physically delimited. We can then try to define it geometrically by considering that it is a volume of earth included in an envelope located at a characteristic length L of the heat exchangers 5 disposed the most outside the field of heat exchangers. heat. The length L can by For example, a characteristic length of the thermal diffusion phenomenon in the storage material.

The storage area may be a heat storage area, in this case characterized by an average temperature above the natural temperature of the soil. The storage area can also be a cold thermal energy storage area, called cryo-energy. It is then characterized by an average temperature lower than the natural temperature of the soil.

As a variant, the same storage area can be used successively in the heat storage domain and in the cryogenic energy storage domain. In this case, it is characterized by a temperature level evolving during a complete cycle of charge / discharge between two extreme values, one higher than the natural temperature of the soil, the other lower than this same soil temperature. .

In yet another variant, the storage area may be subdivided into one or more heat storage areas juxtaposed with one or more cryo-energy storage domains, each domain being defined by its own envelope. The hydronic system 100 controls the circulation of at least one coolant for heat exchange. On the side of the hot source 10, a heat transfer fluid, set in motion by the pump 15 with a flow rate Q10, leaves the hydronic system 100 at the point 207 (direction of the white flow arrow) at a low temperature T10L. receives heat from the source 10 at, for example, a heat exchanger 14 (direction of the black arrow), then returns to the hydronic system 100 at the point 208, at a high temperature T10H.

On the consumer side 20, a heat transfer fluid, set in motion by the pump 25 with a flow rate Q20, leaves the hydronic system 100 at the point 209, at a high temperature T20H, loses heat while circulating in the consumer 20 at for example, a heat exchanger 24 (direction of the black arrow), then enters the hydronic system 100 at point 210, at a low temperature T20L. At each instant, the hot source 10 is characterized by a fluid flow Q10 measured by the flow sensor 18, and two "low" temperature levels T10L and "high" T10H measured by the temperature sensors 17, and the cold source 20 is characterized by a fluid flow Q20 measured by the flow sensor 28, and two "low" temperature levels T20L and "high" T20H measured by the temperature sensors 27.

The hydronic system 100 according to the presently preferred embodiment comprises an upper part called the pumping subsystem 200, an intermediate part said flow control subsystem 300 and a lower part called connection subsystem 400. The hydronic system also includes a control system 500.

The pumping subsystem 200 makes it possible to control the heat transfer fluid flow rates associated with the heat exchanges at the hot source 10, the cold source 20 and the energy storage unit 30. The pumping subsystem 200 allows the following modes of operation:

Injecting all the heat produced by the hot source 10 into the storage unit 30;

Injecting a portion of the heat produced by the hot source 10 into the storage unit 30 and directly transferring the other part of the heat produced by the hot source 10 to the consumer 20;

Feeding the consumer 20 by extracting all the heat to be supplied from the storage unit 30;

Feeding of the consumer 20 in part by direct transfer of the heat produced by the hot source 10 and partly by extraction of heat required from the storage unit 30.

Injection of heat produced by the hot source 10 in certain areas of the storage unit 30 and simultaneously feeding the consumer 20 by extracting heat from other areas of the same storage unit 30.

Internal heat transfer by heat extraction from certain areas of the storage unit 30 and reinjection of this heat into other areas of the storage unit 30. Referring to FIG. 3, the pumping subsystem 200 comprises two circulation pumps 201 and 202 respectively provided with a variable-speed electrical drive, eight shut-off valves controlled in all or nothing 221, 222, 223, 224, 231, 232, 233 and 234, and two bottles (or balloons) 220 and 230, both connected to the same expansion tank 240, thus forming the neutral point of the hydraulic circuit.

It will be appreciated that in this invention, the pressure bottles are not necessarily employed for their ability to store a fluid buffer volume. In the pumping subsystem 200, the pressure-reducing bottles are used for their two following properties: on the one hand, the bottles have the advantage of allowing the transfer of heat energy between two hydraulic loops whose flow rates can be different, without the fluid undergoes a change in temperature at the passage between the two loops, as would be the case with the use of heat exchangers; and, on the other hand, the bottles constitute, between their inlet and outlet ducts, a virtually zero hydraulic resistance which allows the paralleling, between these ducts, of several hydraulic loops each having its own pumping means.

On the left-hand part of FIG. 3, the coolant is able to circulate in a loop comprising the hot source 10 and / or in a loop of the storage unit 30 for the extraction of energy.

When the stop valves 221 and 222 are in the open position, the bottle 220 is connected to the inlet and outlet points 208 and 208 to form a fluid circulation loop in the hot source 10. The heat transfer fluid, put in motion thanks to the pump 15, leaves the balloon 220 at a temperature T10L. It flows to the node A, then to the node B through the open valve 222, to the point 207. The fluid then flows into the hot source 10 where it receives heat. It returns with a temperature T10H in the pumping subsystem 200 at the inlet 208, then flows to the node C, then to the node D through the valve 221 open, and finally returns to the balloon 220. The coolant is also able to circulate in a loop for extracting heat accumulated in the storage material. The pump 201 for circulating the fluid, the latter exits the bottle 220 at a temperature T5L-A to the node A, is oriented towards the outlet point 203 of the pumping subsystem 200. As will be described 5, 6 and 7, between the points 203 and 204, the fluid is able to flow in parallel through one or more elementary loops respectively comprising a heat exchanger 5 or a group of heat exchangers Gi or a series of heat exchanger groups Si, where it receives heat from the storage material. The fluid again enters the pumping subsystem 200 at the point of entry 204 at a higher temperature T5H-A. The fluid finally returns to the balloon 220 via the node of the circuit D. On the right-hand part of FIG. 3, the coolant is able to circulate in a loop comprising the consumer 20 and / or in a loop of the unit storage 30 for energy injection.

The bottle 220 is connected to the outlet 209 and inlet 210 points to form a fluid circulation loop in the consumer 20. The fluid leaving the balloon 220 is set in motion by the pump 25, circulates to the node E then to the exit point 209 with a temperature T20H. Outside the pumping subsystem 200, the fluid flows into the consumer 20 where it gives up heat. It enters the pumping subsystem 200 again at the point of entry 210 with a low temperature T20L. It circulates to the node G then to the balloon 220.

When the stop valves 223 and 224 are in the open position, the fluid is also able to flow from the balloon 220, in a loop for accumulating heat in the storage material. In heat storage mode, the fluid is set in motion by the pump 202. It exits the balloon 220 at a temperature T5H-B to the node of the circuit E. The stop valve 223 being in this case open , the fluid flows to the node F, then to the exit point 205. As will be described hereinafter with reference to FIGS. 5, 6 and 7, outside the pumping subsystem 200, between the points 205 and 206, the fluid is able to flow in parallel in one or more elementary loops respectively comprising a heat exchanger 5 or a group of heat exchangers Gi or a series of groups of heat exchangers Si, where it transfers heat to the storage material. The fluid rises to the point of entry 206 with a lower temperature T5L-B, then flows to the node H. The stop valve 224 is in this case open, the fluid flows to the node G, then returns to the balloon 220.

To allow simultaneous use of the pumping subsystem 200 so as to accumulate heat from the hot source 10 and draw energy from the ground to bring it to the consumer 20, the loops described above are slightly modified as indicated below.

The pumping subsystem 200 includes a second balloon 230, which is then used as a means of hydraulic connection between the fluid circulation loop in the source 10 and the loop for accumulating heat in the storage material. The first balloon 220 retains in this case its function as a hydraulic connection means between the loop for extracting heat accumulated in the storage material and the circulation loop of the fluid in the consumer 20. In this mode of operation, the stop valves 222, 221, 223, 224 are kept closed, while the valves 232, 231, 233, 234 are open.

On the left side of FIG. 3, the bottle 230 is then connected to the nodes B and C to form the fluid circulation loop in the source 10. When the valve 232 is open, the heat transfer fluid, set in motion by the pump 15, leaves the balloon 230 at a temperature T10L, and flows to the connection node B, then to the point 207. The fluid then flows into the source 10 where it receives heat. It returns with a temperature T10H in the pumping subsystem 200 at the inlet 208. The fluid is able to return to the balloon 230 from the node of the network C through the valve 231, the latter being open .

On the right-hand part of FIG. 3, the bottle 230 is then connected to the nodes F and H to form a loop enabling to accumulate heat in the storage material. When the valve 233 is open, the heat transfer fluid, set in motion by the pump 202, leaves the balloon 230 at a temperature T5H-B, flows to the node of the circuit F, then to the exit point 205. heat transfer fluid can then be conveyed to the storage material where it gives up heat. The fluid rises to the point of entry 206 with a lower temperature T5L-B, flows to the node H, and finally returns to the balloon 230 through the valve 234, the latter being open. FIGS. 4A to D show four examples of use of the pumping subsystem 200. The pipes in which the heat transfer fluid is in motion are indicated by solid lines, the stop valves in the open position are indicated in black, and the flow direction of the fluid in these pipes is indicated by arrows. On the other hand, shut-off valves in the closed position are indicated in white and the pipes in which the fluid does not circulate are indicated in dashed lines.

Fig. 4A shows the pumping subsystem 200 in an operating mode for both the extraction of heat from the soil and the heat accumulation in the soil. Such use redistributes heat within the storage area. When this mode is selected, the valves 221, 222 are closed, the valves 223 and 224 are open. The valves 231 to 234 are all closed, thus isolating the balloon 230 from the circuit. The pressure balloon 220 forms a hydraulic connection between the heat extraction loop incorporating the pump 201, and the heat accumulation loop incorporating the pump 202.

FIG. 4B shows the pumping subsystem 200 in an operating mode simultaneously allowing the injection of heat from the hot source 10 and the extraction of heat towards the consumer 20. In this state, the valves 221 to 224 are closed, while valves 231 to 234 are open. The pressure-reducing balloon 220 hydraulically connects the heat extracting loop integrating the pump 201 and the fluid circulation loop to the consumer 20 comprising the pump 25. The balloon As for the baffle 230, it is possible to hydraulically connect the fluid circulation loop in the source 10 comprising the pump 15 and the heat accumulation loop incorporating the pump 202.

FIG. 4C shows the pumping subsystem 200 in an operating mode simultaneously allowing the partial extraction of heat and the circulation in the loop comprising the hot source

10, to produce all the heat delivered to the cold source 20.

In this mode of use, the valves 221, 222 are open and the valves 223 and 224 are closed. The valves 231 to 234 are also closed, thus isolating the balloon 230 from the circuit. The pressure-retaining balloon 220 then has the function of connecting on the one hand the circulation loop of the fluid in the hot source 10 comprising the pump 15 and the loop allowing the extraction of heat comprising the pump 201, and, on the other hand on the other hand, the loop allowing the circulation of heat in the cold source 20 comprising the pump 25. The absence of heat production by the hot source 10 constitutes a particular case of this mode of operation. In this case, the heat delivered to the cold source 20 is completely extracted from the storage unit 30 by the extraction loop comprising the pump 201. Finally, FIG. 4D represents the pumping subsystem 200 in a mode of operation. simultaneously allowing the partial accumulation of the heat produced by the hot source 10 in the storage volume 30 and the transfer of the remaining portion of this heat to supply the cold source 20. In this mode of use, the valves 221 to 224 are open. The valves 231 to 234 are closed, thus isolating the balloon 230 from the circuit. The pressure-reducing balloon 220 makes it possible to connect on the one hand the circulation loop of the fluid in the hot source 10 comprising the pump 15, and on the other hand the loop allowing the accumulation of heat comprising the pump 202 and the loop allowing the circulation of heat in the cold source 20 comprising the pump 25. The absence of heat consumption at the cold source 20 is a particular case of this mode of operation. In this case, the heat produced by the hot source 10 is integrally injected into the storage unit 30 for storage. Referring to FIG. 5, the flow control subsystem

300, allowing the selective circulation of the heat transfer fluid between the pumping subsystem 200 and the storage unit 30, and the connection subsystem 400, making it possible to confer a particular architecture on the storage unit 30, will now be described in detail.

The connection subsystem 400 is an interface for connecting a set of heat exchangers 5, buried in the ground, to the flow control subsystem 300. Although the invention could allow to individually control each heat exchanger 5, it is advantageous, for reasons of cost and ease of implementation, to associate a number of heat exchangers 5 in an exchange unit. An exchange unit, comprising at least one exchanger, then constitutes the finest unit that can be individually controlled. Thus, for example, the storage device 30 of FIG. 5 is organized so as to comprise for example M groups of exchangers Gi (the index i varying between 1 and M). The elementary exchange unit of the storage unit 30 is then constituted, no longer by a single exchanger 5, but by a group of exchangers G. This is particularly advantageous for the large installations covered by the invention.

It is at the level of the connection subsystem 400 that the architecture is organized in different groups Gi (1 <= i <= M) of all the heat exchangers. As shown in FIG. 5, the hot ends 53 of each of the heat exchangers 5 of the same group Gi (1 <= i <= M) are interconnected at a "hot" collector Ui, 1 of the group Gi, and the cold ends 54 of each of the exchangers 5 of the group Gi are connected together at the level of the collector "cold" Ui, 2 of the group Gi. Thus, in this embodiment, between the hot collector Ui, 1 and the cold collector Ui, 2, the different heat exchangers 5 of the group Gi being connected in parallel with each other. The hot collector Ui, 1 is connected to the flow control subsystem 300 via a hot pipe 37i. The cold collector Ui, 2 is connected to the flow control subsystem 300 via a cold pipe 38i. The flow control subsystem 300 may be divided into one part for the heat injection 300B (right part of Fig. 5) and part for the heat extraction referenced by the number 300A (left part of the Figure 5). It is assumed that the storage unit 30 comprises M hydraulic heat exchange loops, each of these loops consisting of a group of exchangers Gi (i varying from 1 to M).

The injection part 300B is connected with the pumping subsystem 200 at the point 205 and the point 206. From the point of view of the physical system constituted by the injection part 300B, the point 205 allows the entry of the heat transfer fluid "hot" and point 206 allows the output of the heat transfer fluid "cold".

The input 205 is hydraulically connected to a branch 301 -B. The branch 301 -B includes M downward channels 31i-B (K = K = M).

Each of the downward channels 31 i-B is respectively connected downstream, via a node Ki, and then the pipe 37i, to the hot collector Ui, 1 of the associated group Gi.

The cold collector Ui, 2 of the group Gi (1 <= i <= M) is connected to a branch 302-B, via the pipe 38i, then a dedicated riser 35i-B passing through the node Li. The connection 302- B is connected to the output 206.

It can thus be seen that between the inlet 205 and the outlet 206, M hydraulic heat extraction loops, each comprising a heat exchanger group Gi (1 <= i <= M), are arranged in parallel.

Connections 301-B and 302-B are equipped with a differential pressure sensor 303-B. The downward channels 31 iB (1 <= i <= M) are respectively equipped with a flow sensor 32i-B, a control valve 33i-B, for adjusting the flow rate in the corresponding loop, and an all-or-nothing stop valve 34i-B. It should be noted that the two valves 33i-B and 34i-B are arranged in series and that the stop valve 34i-B effectively blocks any circulation in the pipe that it equips, a control valve, such as the valve 33i-B, never being completely sealed. Each riser 35i-B is provided with an all-or-nothing shutoff valve 36i-B.

Similarly, in the heat extraction portion 300A, the "cold" fluid is injected into the flow control subsystem 300 through the entry point 203. This inlet 203 is connected to a branch 301-A. From the branch 301 -A, M downcomer 31i-A (1 <= i <= M) are respectively connected to the cold collector Ui, 2 of the exchanger group Gi via the node Li. The hot collector Ui, 1 of each of the groups Gi (1 <= i <= M) is connected to a connection 302-A, via a dedicated upstream channel 35i-A passing through the node Ki. This connection 302-A is itself connected to the outlet point 204. The connection 302-A allows a return of the heat transfer fluid "hot" to the pumping subsystem 200, via the exit point 204. Thus, between the 301 -A and 302-A connections, M hydraulic heat extraction loops are arranged in parallel with each other, each enabling the heat transfer fluid supply the associated heat exchanger group Gi. Connections 301-A and 302-A are equipped with a differential pressure sensor 303-A. The downward channels 31 iA (1 <= i <= M) are respectively equipped with a flow sensor 32i-A, a control valve 33i-A for adjusting the flow rate in the corresponding loop and a valve stop 34i-A to completely stop the circulation of heat transfer fluid in the associated loop.

Each riser 35i-A is provided with an all-or-nothing shutoff valve 36i-A.

Note for reasons of economy and ease of assembly and maintenance, the descending pipes 31i-B (1 <= i <= M) and the risers 35i-A which lead both to the same hot collector Ui , 1 advantageously have a common section 37i, the hot collector Ui, 1 to the node Ki. In the same way, the descending pipes 31 iA and the risers 35i-B connected to the same cold collector Ui, 2 have advantageously a common section 38i, in this case the cold collector Ui, 2 at the node Li.

A loop comprising a group of exchangers Gi (1 <= i <= M) is then either activated by heat injection, this loop then being connected to the branches 301 -B and 302-B, or activated for heat extraction, this loop then being connected to the connections 301-A and 302-

A, or inactive, this loop is then hydraulically isolated from the circuit.

The flow rate in each of the activated heat-injection loops is regulated to its individual value by adjusting the pressure drop created by the corresponding control valve 33i-B (1 <= i <= M). The flow measurement associated with this regulation is ensured by the flow sensor 32i-B. In order for the different flow controllers to work together, the flow adjustment in any of the activated loops for the injection must have no influence on the flow in the other loops also activated in injection. In other words, the M flows in the downstream channels 31 iB (1 <= i <= M) must be independent of each other. This is achieved by maintaining a constant hydraulic pressure difference independent of the total fluid flow, between the branch 301-B and the branch 302-B. For this, the circulation pump 202 of the pumping subsystem 200 is driven by an electric motor provided with a variable speed control device, operating in differential pressure regulation mode: the speed of the pump 202 is regulated to maintain the differential pressure between the two connections 301 -B and 302-B at a predetermined preset value, the measuring loop of this regulation being provided by the differential pressure sensor 303-B. Since the pressure difference between the connections 301-B and 302-B is kept constant, each of the M flows in the pipes 31 iB (1 <= i <= M) can be regulated independently. Note that on the side of the connection 302-B, the fluid flows to the bottle 220 through the stop valve 224, or to the bottle 230 through the stop valve 234, depending on the mode. selected operating mode. In both cases, connection 302-B is hydraulically connected to the neutral point of the circuit only through a shut-off valve in the open position, representing a very low pressure drop. The pressure at this connection 302-B can be considered independent of the total fluid flow, which gives a great stability to the differential pressure regulation between the connections 301 -B and 302-B. In the same way, the flow rate in each of the activated loops in the heat extraction is regulated to its individual value by the adjustment of the pressure drop created by the control valve 33i-A (1 <= i <= M ). The flow measurement associated with this regulation is ensured by the flow sensor 32i-A. The M flows in the downward channels 31i-A (1 <= i <= M) must be independent of each other. This is achieved by maintaining a constant hydraulic pressure difference independent of the total fluid flow, between the connections 301-A and 302-A. For this, the circulation pump 201 of the pumping subsystem 200 is also driven by an electric motor provided with a variable speed control device, operating in differential pressure regulation mode: the speed of the pump 201 is regulated to maintain the differential pressure between the two connections 301 -A and 302-A at a predetermined preset value, the measuring loop of this regulation being provided by the differential pressure sensor 303-A. Since the pressure difference between the connections 301 -A and 302-A is kept constant, each of the M flows in the pipes 31 iA (1 <= i <= M) can be regulated independently.

It will be noted that on the side of the connection 302-A, the fluid flows directly to the balloon 220. The connection 302-A is thus hydraulically connected to the neutral point of the circuit, so that the pressure at this connection is independent of the total flow of fluid, which gives a great stability to the differential pressure regulation between the connections 301 -A and 302-A. In FIG. 6A, the flow control subsystem 300 is represented in an operating mode for the energy injection using a heat exchange loop comprising the group of exchangers Gi (1 <= i <= M). Pipes in which the heat transfer fluid is in motion are indicated by solid lines, the stop valves in the open position are indicated in black, and the direction Fluid flow in these pipes is indicated by arrows.

In this mode of operation, it is desired to inject heat into the ground, for example from the hot source 10. As a result, the fluid at temperature T5H-B is introduced through the inlet 205 at the connection 301 -B . When the stop valve 34i-B corresponding to the group Gi is actuated to be in the open state and the stop valve 36i-A is simultaneously actuated to be in the closed state, the pressurized fluid is conveyed via the pipes 31 iB and 37i to the hot manifold Ui, 1 where it is distributed between the various heat exchangers 5 of the group Gi. The temperature of the coolant T5H-B is higher than the average temperature of the medium T2. As a result, the heat of the coolant is transferred to the storage material. At the outlet of each of the exchangers 5, the coolant is collected by the manifold Ui, 2, then routed via the pipes 38i and 35i-B to the connection 302-B, the shutoff valve 36i-B being actuated to be in position. the open state and the stop valve 34i-A being simultaneously actuated to be in the closed state. Finally, the heat transfer fluid, having a temperature T5L-B, is conveyed to the outlet point 206. The flow rate of the fluid in the loop which has just been described is controlled by the valve 33i-B.

In FIG. 6B, the pump subsystem 300 is shown in an operating mode for heat extraction using a heat exchange loop comprising the group of exchangers Gi (1 <= i <= M). By opening the valves 34i-A and 36i-A while closing the valves 34i-B and 36i-B, a loop is activated which includes the downcomer 31 iA, the common line 38i the group of exchangers Gi provided with its two cold manifolds Ui, 2 and hot Ui, 1, the common pipe 37i, and the riser pipe 35i-A. A description equivalent to that made above for the injection could be made for the extraction operating mode using the part 300A to describe how the heat transfer fluid introduced at point 203 at the temperature T5L-A appears at point 204 to the temperature T5H-A. Finally, a mode of operation of the flow control subsystem 300 in which the loop comprising the group of exchangers Gi (1 <= i <= M) is kept inactive is obtained by closing the valves 34-A, 36i-A, 36i-B and 34i-B. Referring to Figure 7, for a number of applications covered by the invention, the operation in injection and / or extraction requires a significant temperature difference between the incoming fluid and the fluid leaving the storage unit . To satisfy this operation, it is often necessary to connect several groups of exchangers in series.

In this case, during its passage through the storage unit 30, the heat transfer fluid no longer passes through only one exchanger (one exchanger group consisting of exchangers in parallel), but several series exchangers (belonging to one another). each to one of the groups connected in series). Thus the amount of heat exchanged with the storage material and the temperature variation experienced by the fluid are increased. However, because of variations in flow rates and temperatures of the fluid at the inlet of the system and the need to be able to precisely control the physical areas of injection and heat extraction, it is advantageous that series of exchangers can be configured to decide the number of groups used in a series and the position of the resulting series.

In order to limit the costs induced by the combinatorial aspect, it is proposed the following compromise represented in FIG. 7. For a particular embodiment of the invention, it is decided, prior to the realization, to have a fixed number S of series of exchangers Si (1 <= i <= S) inside the storage means 30. Each series Si comprises a fixed number Mi of groups of exchangers GiJ (1 <= j <= Mi) ordered from 1 to Mi. The system has means for configuring, at any time, a position branch and variable length as a sub-series of a maximum series SiMax consisting of all groups of exchangers Gi connected in series.

More precisely, it is at the level of the connection subsystem 400 'that the serialization of the groups of exchangers is organized. FIG. 7 is a diagrammatic representation in injection mode of heat, part of the flow control subsystem 300 'and the connection subsystem 400' when the activated loop no longer has a single group of exchangers but a branch of the series Si. The sub-system of connection 400 'organizes the storage unit 30 so that the cold inputs of the exchangers of a group of heat exchangers Gi j and the hot inputs of the heat exchangers of the next group Gij + 1 are connected to the same collector UiJ, with the exception of the first collector Ui, 1 which is connected only to the hot inputs of the first group Gi, 1 of the series Si, and the last collector Ui, Mi + 1 which is connected only to the cold inputs of the last group Gi ₁ Mi of the series Si. There are thus Mi + 1 collectors.

The principle implemented in the flow control subsystem 300 'to activate the loop comprising a branch of the series Si (1 <= i <= S) and to regulate the flow of heat transfer fluid in this loop is identical to what has been previously described in the case of the activation of a group of exchangers. The difference lies in the fact that, for any series of exchanger groups Si (1 <= i <= S), the hot line 37i of the flow control subsystem 300 'is provided with a flow switch 31Oi and the cold line 38i is provided with a flow switch 32Oi.

A flow switch is a bidirectional device hydraulically connecting a primary line to an arbitrary number of secondary lines each provided with an all-or-nothing bidirectional valve. By opening a valve while keeping all the others closed, the flow switch connects the primary line to a single secondary line, thus opening a path and a single path for the coolant.

For any series Si (1 <= i <= S), the flow switch 31Oi comprises Mi + 1 secondary lines respectively provided with a bidirectional controlled valve 31 ji (1 <= j <= Mi + 1) and connected via the ViJ node at Mi + 1 collectors UiJ (1 <= j <= Mi + 1). The flow switch 32Oi comprises Mi + 1 secondary lines respectively provided with a bidirectional controlled valve 32ji (1 <= j <= Mi + 1) and connected via the node ViJ to the collector UiJ (1 <= j <= Mi + 1 ). Given two indices p and q (1 <= p <= Mi, 1 <= q <= Mi), the valve of index p (noted 31 ft) of the flow switch 31Oi, associated with the secondary pipe connected to the collector Ui, p, as well as the valve of index q + 1 (denoted 32 (q + 1) i) of the flow switch 32Oi, associated with the secondary pipe connected to the collector Ui, q + 1, are both actuated to be in the open state. The coolant, from the connection 301 -B to the temperature T5H-B, is then oriented by the flow switch 31Oi to the collector Ui, p. It enters the series Si by the group of exchangers Gi, p, circulates successively in all the groups of exchangers of the series Si between Gi, p and Gi, q inclusive, where it exchanges heat with the material of storage. It emerges from the series Si by the collector Ui, q + 1 at a temperature T5L-B lower than T5H-B. It is then directed to the branch 302-B through the flow switch 32Oi. Thus the circulation of the coolant is restricted to the only branch of the Si series located between groups Gi, p and Gi, q. Note that when p = q, only the group Gi, p is crossed. In addition, the system makes it possible to reverse the direction of movement in the branch by simply permuting the indices p and q.

A similar description could be made in energy extraction mode.

The possibility of selecting, within a series Si (1 <= i <= S) activated by injection or extraction, the branch which will be in adequacy with the desired operation, in particular with the required values of fluid temperature entering and leaving the storage area, and restricting the flow of fluid to this single branch, in an arbitrary sense, thus allows to limit and locate the phenomenon of thermal diffusion throughout the storage area. In addition, since the appropriate branch has been selected and activated, the regulation of the flow of coolant circulating in this branch makes it possible to adjust the temperature of the fluid at the outlet of the branch and thus to adapt it to the value required by the source. in heat injection mode or by the consumer in heat extraction mode.

In a more general way, the connection system can be seen as a fixed assembly for grouping exchangers 5 in parallel or in series. The connection system can be brought to undergo the addition (and more rarely the withdrawal) of certain groups of exchangers, in order to adapt the total power of injection and / or extraction of heat to the needs of the application. Apart from these exceptional operations, the connection system is fixed and undergoes no structural variation. The connection system is more specific to each application insofar as the overall architecture of the storage unit 30, in particular the number and location of the exchangers 5, their association in groups and the possible connection of certain groups in series, will be the result of a case-by-case study for each application, and will depend on various parameters such as the amount of energy to be stored, the characteristics of the source and the consumer, the necessary injection / extraction power , the thermal characteristics of the storage material, or the coefficients of infiltration or underground circulation of water through the storage unit 30.

The flow control subsystem makes it possible to select with the finest particle size possible, the area of the storage area suitable for extracting or injecting heat energy. The activation of an exchanger, a group of exchangers or all or part of a series of exchanger groups makes it possible to control the thermal power injected or extracted in the corresponding domain of the storage area.

Referring again to Figure 2, the hydronic system 100 according to the invention comprises a control loop for the automatic actuation of the different valves to activate one or more exchangers according to the selected operating mode.

For this, the hydronic system 100 and the storage unit 30 are equipped with a set of temperature sensors. These are temperature sensors 6 disposed in the ground or in the sheath 55 of the heat exchanger, and possibly temperature sensors 17 and 27 arranged at different points of the hydronic system to determine the temperature of the coolant. The sensors 6, 17 and 27 allow a local measurement of the temperature. Other types of sensors can be used. In the description of Figure 5, reference was made to 32i-A and 32i-B sensors that provide flow information. The source-side loop and the consumer-side loop can also be equipped with flow sensors 18 and 28 to know at any time the thermal power (flow product by the difference of the temperatures of the coolant in the inlet and outlet piping ) More generally, the hydronic system 100 and the storage unit 30 may include a plurality of sensors and actuator for physically acting on the programmable controllers for deporting the input / output operations, performing remote operation successions and generating operating state variables. The output signals of the hydronic system 100 and the storage unit 30 thus include all signals from the sensors, actuators and controllers. The input signals of hydronic system 100 and storage unit 30 include all signals to actuators and controllers.

The output signals of the hydronic system 100 and the storage unit 30 are conveyed as electrical signals to a computing unit 500.

The calculation unit 500 comprises storage means and calculation means. The instructions of a program are stored in the storage means and are executed by the calculation means. The calculation unit 500 comprises an input-output interface adapted to receive the output signals of the hydronic system 100 and the storage unit 30 as input and to output the input signals of the hydronic system 100 and the output signal. storage unit 30 for actuating the various controlled valves and control commands of the pump subsystem 200 and / or the flow control subsystem 300.

According to the signals coming from the source and the consumer, among others the instantaneous thermal power supplied by the source 10 and the instantaneous thermal power demanded by the consumer 20, as well as the output signals of the hydronic system 100 and the control unit. storage 30 defining the current state and the In the present configuration of the zone, the computing unit 500 is able to determine the composition of the loops of the storage unit that must be configured and activated by the hydronic system 100.

For this purpose the calculation unit 500 determines, for each active loop, whether the activation of the loop must be done by injection or heat extraction. In heat injection mode, the group Gi (1 <= i <= M) (or series of groups Si (1 <= i <= S)) will be connected to the connections 301 -B and 302-B by the opening of the two stop valves 34i-B and 36i-B. In heat extraction mode, the group Gi (1 <= i <= M) (or series of groups Si (1 <= i <= S)) will be connected to the connections 301 -A and 302-A by the opening of the two stop valves 34i-A and 36i-A.

The unit 500 also calculates the flow rate of the heat transfer fluid that must pass through this loop. This flow flowing in the group Gi (1 <= i <= M) (or series of groups Si (1 <= i <= S)) will then be regulated to the value thus calculated using the control valve 33i -B in heat injection mode, and using the control valve 33i-A in heat extraction mode.

In the embodiment variant described above in relation to FIG. 7, during the activation of a series of exchangers Si (1 <= i <= S), the computing unit 500 also defines the topology of the branch of this series Si which will be crossed by the heat transfer fluid by defining the value of the indices p and q. Corresponding groups Gi, p and Gi, q will be activated using the associated flow switches 31Oi and 32Oi.

An embodiment for designating the active loops as a function of the output signals of the hydronic system 100 and the storage unit 30 will now be described in detail.

Studies prior to the storage unit 30 and its location in a particular geological site make it possible, among other things, to define a plurality of successive optimal states of the storage area. Each of the optimal states thus defined can be represented by a three-dimensional map giving the temperature at any point of the storage area at a given date. For example, in the case of a heat storage unit powered by solar collectors, successive optimal maps can be determined for all summer months with the criterion of maintaining a low temperature gradient at level of the envelope of the storage area, ie maintains a flow of low heat energy through this envelope; then, at the end of the charging cycle, the optimal cards can be determined with another criterion of the maximum filling of the storage volume. Other types of optimal states, represented by their associated optimal map, can be determined with other criteria by the user. For example, for the same storage unit 30, one may want to establish a summer map and an autumn map. The summer map defines several sectors corresponding to storage at different temperature levels in summer: thus the storage area may include a sector dedicated to the heat accumulation produced by solar panels for heat production. winter and a storage area dedicated to a summer air conditioning application. The goal here is to allow the system to accumulate heat for the next winter, while promoting a suitable area for an air conditioning application, so as to increase energy efficiency. The autumn map can then be defined so as to eliminate, in the storage unit 30, this sector dedicated to the air conditioning to store there now heat from the solar panels, and this so that the unit of Storage 30 has a storage temperature spectrum that allows winter heat generation to operate at optimum energy efficiency.

More generally, a card designates any means making it possible to obtain information on the overall state of the storage unit 30 at a given date; the global state of the storage unit being characterized by the knowledge, possibly approximate, of the temperature at each point of the storage unit 30.

During the use of the storage system, one of the optimal cards is loaded into the memory means of the computing unit 500. This optimal card is then considered as a goal to be achieved over time. For example, in the case of a heat storage unit powered by solar collectors, the user will load the optimal card at the end of the cycle if he wants the storage area to contain a maximum of heat energy for example in the month October, just before entering the winter months which are months of high energy consumption during which it is known that the heat source will produce little energy.

The calculation unit 500, allows at any time, according to the temperature measurements recorded by the various sensors 6, to make a three-dimensional instantaneous map of the temperature in the storage area. This map gives the instantaneous state of the storage area.

According to the instantaneous map, the optimal map fixing the objectives to be achieved and information concerning the instantaneous state of the source and the consumer (flow rates and temperatures), the computing unit 500 emits actuating signals for qua at every moment the mode of operation of the hydronic system 100 meets the needs of the consumer and the source, but also the final objective to be achieved. For example, the computing unit 500 locally evaluates the differences between the temperature given by the optimal card and the temperature given by the flash card. If the thermal power produced by the source is greater than that demanded by the consumer, the unit 500 selects the mode of partial energy injection operation and activates the heat exchangers located in a cold part of the heating zone. storage which has temperature levels adapted to the inputs of the source and which has a temperature deficit with respect to the objective board. If, on the contrary, the thermal power produced by the source is not sufficient to supply the consumer, the unit 500 selects the mode of partial energy extraction operation and activates in heat extraction the heat exchangers located in a hot part of the zone. storage which has temperature levels adapted to the needs of the consumer and which has a temperature overrun compared to the objective board. In this way the temperature distribution inside the zone converges in time towards the optimal state.

The computing unit 500 may have a user interface allowing an operator to define completely, at each instant, the configuration of the hydronic system 100: in this case, it is the operator himself who positions the input signals. of the hydronic system 100 and the storage unit 30 to control the evolution of the storage unit 30.

The computing unit 500 may comprise a predictive control or control method for calculating the input signals of the hydronic system 100 and the storage unit 30 in order to control the evolution of the storage unit 30: in this case, the computing unit 500 relies on an optimization method to determine the input signals of the hydronic system 100 and the storage unit 30 to satisfy the goal of transition between the state current of the storage unit 30 corresponding to the flash card, and a desired state corresponding to an optimum card.

In the immediately preceding case, the optimization method can take into account a set of constraints represented by a cost function (optimization under constraints), so that the constraints are satisfied when the cost function is optimum. In this case, the constraint optimization method aims to determine the input signals of the hydronic system 100 and the storage unit 30 to satisfy the transition goal between the current state of the unit of storage corresponding to the instant map, and a desired state corresponding to an optimum map, the transition taking an optimum path at the cost function, thus satisfying the constraints.

Thus, from the above immediately, the conduct of the evolution of the storage unit can be carried out taking into account constraints related to the overall efficiency of an energy system using the invention. In particular, the constraints can be strongly linked to the level of energy efficiency and / or the cost of exploitation of the sources and / or consumers. Constraints derived from weather forecasts can also be taken into account, in order to better adapt to the future needs of consumers, and / or the future production of producers, especially if they use energy renewable.

Finally, constraints related to the timing of heat production by a producer and / or consumption of heat by a consumer can also be taken into account. Figs. 8A to 8D show a simple example of optimal maps associated with a given depth of a heat storage unit. FIGS. 8B, 8C and 8D represent the desired temperature distribution for three different and successive instants during a heat injection cycle in the storage zone. The temperature of each isothermal curve is indicated on it in degrees Celsius. In this example, the storage area considered contains 42 exchangers 5 arranged regularly and denoted Ei j (1 <= i <= 7, 1 <= j <= 6). The system shown is based on a group of exchangers in 14 series of three exchangers (each series being able to give rise to sub-series in accordance with the present invention), numbered S1 to S14, defined according to (without taking into account the direction of circulation fluid): S1 = E11, E12, E13; S2 = E14, E15, E16; S3 = E21, E22, E23; S4 = E24, E25, E26; S5 = E31, E32, E33; S6 = E34, E35, E36; S7 = E41, E42, E43; S8 = E44, E45, E46; S9 = E51, E52, E53; S10 = E54, E55, E56; S11 = E61, E62, E63; S12 = E64, E65, E66; S13 = E71, E72, E73; S14 = E74, E75, E76. The storage area further comprises temperature sensors not shown in Figure 8A. In the initial state, the temperature of the storage zone is equal to the outside temperature of the soil, ie approximately 15 ° C. It is then desired to inject heat so that one can, at any time of the loading cycle, have the largest possible amount of directly exploitable thermal energy, that is to say a temperature of about 40 to 50 ^° C. In addition, it is sought to create gradients at the edge of the storage area which make it possible to limit the losses during the injection cycle.

It is decided to inject the thermal energy into 3 distinct phases of the charging cycle, which phases are respectively represented by FIGS. 8B, 8C and 8D. The procedure consists in forming and then enlarging a central zone having a temperature of 45 to 50 ^° C. so that, at the end of the injection, the envelope of the storage zone is as close as possible to the topology of the storage unit to maximize energy recovery during the extraction phase. In this example, the storage area has a single domain defined by a temperature of 45 to 50 ° C, but the storage area could have different domains each having a particular temperature range.

There is a hot source delivering water as heat transfer fluid at a temperature of 60 ⁰ C for a flow rate of 10 kg / s. In the first phase, in order to fulfill the objective presented in FIG. 8B, the series S5, S6, S7, S8, S9 and S10 are selected, and the branches S'5 = E33; S'6 = E34; S'7 = E43; S'8 = E44; S'9 = E53; S'10 = E54 are configured. The fluid is injected in parallel in branches S'5 to S'10 until the temperature of the storage area is as close as possible to that shown in Figure 8B.

When this first phase is reached, the system configures (taking into account the direction of flow of the fluid) the following branches: S "3 = E23, E22; S" 4 = E24, E25; S "= E33, E32; S6 = E34, E35; S = E43, E42; S8 = E44, E45; S = 9 = E53, E52; S10 = E54, E55; S "11 = E63, E62; S12 = E64, E65. Then it performs the injection in parallel in the branches S "3 to S" 12 until the temperature of the storage area is as close as possible to what is shown in Figure 8C. When this second phase is reached, the system configures

(taking into account the flow direction of the fluid) finally the following branches: S '"1 = E13, E12, E11; S'" 2 = E14, E15, E16; S '= 3 = E23, E22, E21; S' = 4 = E24, E25, E26; S '= E33, E32, E31; S6 = E34, E35, E36; S = E43, E42, E41; S = E44, E45, E46; S '= E53, E52, E51; S' = E54, E55, E56; S = 11, E63, E62, E61, S12 = E64, E65, E66; S = 13, E73, E72, E71, S14 = E74, E75, E76. The injection is then carried out in parallel in the branches S '"1 to S'" 14 until the final state of the storage area shown in FIG. 8D.

Depending on the input and output injection temperatures imposed by the source or extraction imposed by the consumer, it is possible to develop several scenarios of injection or extraction involving series or groups of exchangers and, possibly, different areas of the storage area having different average temperatures, and anticipating the impact of each scenario on the overall efficiency of the facility. The system can then rely on processes related to combinatorial optimization to drive the charge / discharge cycle while optimizing the overall efficiency.

Thus, the computing unit 500 provides optimum control of the temperature distribution in the storage area 30 throughout the charge / discharge cycle.

Thus, the hydronic system 100 according to the invention makes it possible: to control the thermal storage unit 30 according to three modes of operation: heat injection, heat extraction, simultaneous injection and extraction, actively control throughout the charge / discharge cycle the temperature distribution inside the storage area in order to minimize the amount of energy lost at the limits during a complete cycle, while optimizing the volume of storage material used, - to ensure optimal control of the injection and heat extraction processes in the thermal storage device 30, in order to limit the diffusion phenomena in the storage material at the origin thermal losses, in particular by restricting the circulation of fluid to the only zones that have been selected for the injection or the extraction, in adequacy with the desired operation, in particular with the values required temperature of the fluid entering and leaving the storage area. to ensure optimal control of the injection and heat extraction processes in the thermal storage device 30, in order to partition the thermal storage device 30 into one or more different heat zones in order to present the producers and temperature ranges and amounts of heat adapted to their applications, in particular by restricting the circulation of fluid to the only zones that have been selected for injection or extraction, in adequacy with the desired operation, in particular with the required values temperature of the fluid entering and leaving the storage area. to ensure optimum control of the injection and heat extraction processes in the thermal storage device 30, according to one of the previously described operation, while satisfying arbitrary constraints, including those related to the overall efficiency of the energy system, including sources and / or consumers. to control the effects of transverse hydrogeological infiltrations, as far as possible, by transferring heat between different zones of the same thermal buffer 30.

Although the invention has been described with reference to a particular embodiment, it is not limited to this embodiment. It includes all the technical equivalents of the means described as well as their combinations which come within the scope of the invention.

Claims

1. A method for controlling a thermal energy storage unit in the ground comprising a plurality of heat exchangers buried in the ground, each of said heat exchangers allowing a heat energy exchange between a heat transfer fluid therethrough and the ground , said energy storage unit being disposed at the interface between a source and a consumer of heat energy for storing thermal energy, characterized in that the temperature is measured at different points of the ground by means of buried temperature sensors, the temperatures and flow rate of a heat transfer fluid at the inlet and at the outlet of the source for determining the thermal power supplied by the source, and the temperatures and flow rate of a heat transfer fluid at the consumer's inlet and outlet for determining the thermal power to be supplied to the consumer, and in that the storage of thermal energy in said storage unit is optimized by selecting active exchangers among said plurality of exchangers based on temperature measurements, flow measurements and thermal power measurements.

2. Method according to claim 1, characterized in that it comprises the steps of: previously determine an optimum map of the temperatures in the soil; determining an instantaneous map of the temperatures in the soil by means of said temperature measurements made at different points of the ground; selecting active exchangers from said set of exchangers as a function of the local temperature differences between said instantaneous card and said optimal card, temperatures and flow rate of the heat transfer fluid at the input and output of the source, and temperatures and flow rate of the coolant in input and output of the consumer, in order to pass the storage unit of the current state corresponding to the instantaneous map to the state corresponding to the optimum map, the transition using an arbitrary path or imposed by a set of constraints.

3. Method according to claim 1 or claim 2, characterized in that, one moves heat inside the storage unit by circulation of the heat transfer fluid between a loop comprising at least one exchanger activated extraction. and a loop comprising at least one exchanger activated by injection.

4. Method according to one of claims 1 to 3, characterized in that it comprises an additional step consisting:

When the thermal power supplied by the source is adapted to the thermal power used by the consumer, to activate none of the exchangers and to circulate the heat transfer fluid between a loop comprising the source and a loop comprising the consumer; When the thermal power supplied by the source is not usable by the consumer, circulating the heat transfer fluid between a loop comprising the source and a loop comprising injection-activated exchangers, and simultaneously circulating the heat transfer fluid between a loop comprising the consumer and a loop comprising exchangers activated for extraction;

When the thermal power supplied by the source is greater than the thermal power used by the consumer, circulating the heat transfer fluid on the one hand in a loop comprising the source and on the other hand in a loop comprising the consumer and a loop comprising exchangers activated by injection;

When the thermal power used by the consumer is zero, to totally inject the thermal power supplied by the source into the storage unit;

When the thermal power supplied by the source is lower than the thermal power used by the consumer, circulating the heat transfer fluid on the one hand in a loop comprising the consumer and on the other hand in a loop comprising the source and a loop comprising exchangers activated for extraction;

When the thermal power supplied by the source is zero, to fully extract the thermal power used by the consumer of the storage unit.

5. Hydronic control system of a soil thermal energy storage unit having a plurality of heat exchangers buried in the ground, each of said heat exchangers allowing an exchange of heat energy between a heat transfer fluid passing therethrough and the ground, said hydronic system being intended to be disposed between a source of heat energy, a consumer of heat energy and said unit storage device, characterized in that it comprises: a plurality of temperature sensors buried in the ground; temperature and flow rate sensors for measuring a thermal power supplied by the source and a thermal power used by the consumer; grouping means for grouping said exchangers into a plurality of elementary exchange units, an exchange unit comprising at least one exchanger; and, activation means for selectively activating said elementary exchange units.

6. System according to claim 5, characterized in that, an exchanger having a hot end and a cold end, the grouping means are used to form groups of exchangers, as exchange unit, the different hot ends. said exchangers of the same group being connected to a hot collector and the cold ends of these same exchangers being connected to a cold collector, the different exchangers of said group being in parallel with each other.

7. System according to claim 6, characterized in that said grouping means are used to form series of exchangers as exchange unit, a series of exchangers (S) having a number (nS) of groups of exchangers (Gi), the cold collector of one of said groups (Gi) of a series being connected to the hot collector of the next group (Gi + 1) of said series, so that said groups of the same series of exchangers are arranged in series between an initial group (G1) and a final group (Gn).

8. System according to claim 7, characterized in that said grouping means comprise first and second switches, each switch having a main line and secondary lines, the hot collector of a group of exchangers being connected to said first switch via a secondary pipe thereof provided with a stop valve, and the cold collector of said group being connected to said second switch via a secondary pipe thereof provided with a stop valve, so that the grouping means allow to arbitrarily select, at a given instant and according to the position of the valves of the first and second switches, a first group of exchangers (Gp) and a last group of exchanger (Gq), to form between them a sub exchanger series (S ') used as exchange unit.

9. System according to claim 5 or claim 8, characterized in that the activation means comprise injection activation means adapted to form a hydraulic injection loop comprising at least one exchange unit for injection energy, and extraction activation means adapted to form a hydraulic extraction loop having at least one exchange unit for energy extraction; in that said injection activation means comprise an inlet injection branch and an outlet injection branch, each exchange unit being connected by its hot end to said inlet injection branch and by its cold end at said output injection connection to form an injection connection between the inlet and outlet injection connections, the different exchange units then being in parallel with each other between said injection connections input and output, each injection connection thus defined being provided with injection rate control means, so that the flow rate in said injection connection considered can be arbitrarily fixed during an injection, and in that said extraction activation means comprise an input extraction branch and an output extraction branch, said exchange units being respectively connected ected by their cold end to said inlet extracting branch and by their hot end to said outlet extraction branch, to form an extraction connection between the inlet and outlet extraction branches, the individual units exchange then being in parallel with each other between said input and output extraction connections, each extraction link thus defined being provided with control means of extraction rate, so that the flow rate in said extraction connection considered can be arbitrarily set during an extraction.

10. System according to claim 9, characterized in that a differential pressure sensor is connected between said input and output connections, a supply line of the input connection comprises a differential pressure regulated pump according to the measurement made by said sensor, so that the flow in any of the parallel links between the input and output connections can be individually regulated.

11. System according to one of claims 5 to 10, characterized in that it is provided with pumping means comprising pumps adapted to circulate the heat transfer fluid in an injection loop having at least one exchange unit operating in energy injection and an extraction loop comprising at least one exchange unit operating in energy extraction, and connection means allowing at least one of: connection of a circulation loop in the source with the injection loop; the connection of the circulation loop in the consumer with the extraction loop; connecting the circulation loop in the source with the injection loop, and simultaneously, connecting the circulation loop in the consumer with the extraction loop; the connection of the extraction loop with the injection loop; the connection of the circulation loop in the source with the circulation loop in the consumer; the connection of the extraction loop with the injection loop, and simultaneously the connection of the circulation loop in the source with the circulation loop in the consumer.

12. System according to claim 11, characterized in that said connection means further allow: the connection of a circulation loop in the consumer with an extraction loop and the circulation loop in the source; and, the connection of a circulation loop in the source with an injection loop and the circulation loop in the consumer.

13. The system of claim 11 or claim 12, characterized in that said connection means comprise: a first pressure-reducing bottle, connected to an expansion vessel forming the neutral point of said hydraulic system, said first bottle breaks pressure being connected to said extraction loop on the one hand and to said circulation loop in the consumer on the other hand; a first pair of stop valves whose state makes it possible to connect said circulation loop in the source to said first pressure-reducing bottle; a second pair of stop valves whose state allows the injection loop to be connected to said first pressure bottle.

14. System according to claim 13, characterized in that said connection means further comprise: a second pressure-reducing bottle connected to said expansion vessel forming the neutral point of said hydraulic system; a third pair of shutoff valves whose state, in relation to the state of said first pair of valves, enables said circulation loop in the source to be connected to said second pressure bottle, the extraction loop being connected said first pressure bottle; a fourth pair of shutoff valves whose state allows, in relation to the state of the second pair of valves, to connect said injection loop to said second pressure bottle, the circulation loop in the consumer being connected to said first pressure bottle.

15. System according to one of claims 5 to 14, characterized in that, said activation means, connection, and pumping being automatically operable, the system comprises a calculation unit adapted to receive the measurement signals transmitted by the different sensors and to emit a control signal to said activation, connection and pumping means, said calculation unit executing the instructions of a program stored in storage means of said calculation unit for implementing a method according to any one of claims 1 to 4.

16. System for storing heat energy in the soil, characterized in that it comprises a hydronic system according to one of claims 5 to 15 and an energy storage unit comprising at least ten exchangers.