Device for producing and using a heat transfer fluid in a closed circuit

Abstract

The invention relates to a device for producing and using a heat transfer fluid in a closed circuit according to operating cycles, the device comprising: - a buffer tank (1) comprising two compartments, a recovery compartment (2a) and a storage compartment (2b) separated by a flexible membrane (3), - a consumption unit (7), configured to extract calories or frigories from the heat transfer fluid, and - a regeneration unit (9) of the heat transfer fluid, configured to supply calories or frigories to the heat transfer fluid, characterized in that the device comprises a control member (10), said control member (10) comprising: - means for recovering a forecast (11) of the energy requirements of said consumption unit; - search means configured to take into account said forecast (11) and determine an optimal control strategy for said regeneration unit (9).Figure for abstract: Fig 1.

Description

Title of the invention: Device for producing and using a heat transfer fluid in a closed circuit Technical field

[0001] The present invention relates to the field of production and use of a heat transfer fluid. More particularly, it relates to a device for optimizing the production of thermal or cooling energy according to consumption needs.

[0002] The invention finds a particularly advantageous application for achieving energy savings. Prior art

[0003] When a system uses a heat transfer fluid as a vector for thermal or cooling energy, it is known to use a buffer tank. The buffer tank makes it possible to store the heat transfer fluid at a certain “hot” or “cold” temperature, with a view to injecting it into a consumption circuit. The consumption circuit may correspond, for example, to a circuit comprising radiators for heating a home or a circuit comprising heat exchangers for cooling a room, for example a cold room.

[0004] The buffer tank therefore allows a temporal decorrelation, at least partial, of the production of the heat transfer fluid and its use.

[0005] After the heat transfer fluid has been used to provide thermal or cooling energy, the thermal power of the heat transfer fluid is reduced. The thermal fluid is then "lukewarm", - either because the heat transfer fluid is initially "hot" so that its temperature has decreased after circulation in the consumption circuit, - or because the heat transfer fluid is initially "cold" so that its temperature has increased after circulation in the consumption circuit.

[0006] Two solutions are then possible.

[0007] The “warm” heat transfer fluid can be reinjected directly into the buffer tank, which has the disadvantage of reducing the thermal power of the entire heat transfer fluid in the tank, either by reducing the temperature of a “hot” heat transfer fluid, or by increasing the temperature of a “cold” heat transfer fluid.

[0008] Alternatively, thermal power can be reinjected into the “warm” heat transfer fluid, i.e. the “warm” heat transfer fluid can be heated or cooled before its reinjection into the buffer tank. In this case, the “warm” heat transfer fluid can be stored before and / or after its heating or cooling in one or more intermediate storage tanks, which has the disadvantage of increasing the size of the installation. In the absence of an intermediate storage tank, the "warm" heat transfer fluid must be heated or cooled at a flow rate equivalent to the outlet flow rate of the buffer tank, which requires significant sizing of the heat transfer fluid regeneration unit. This regeneration unit can typically be a heat pump or a cooling unit.

[0009] In order to propose a solution to these drawbacks, document DE3115988 proposes a buffer tank comprising a flexible membrane, separating a preheated liquid and a hot liquid.

[0010] However, the solution set out in this document does not allow the energy requirements of the installation to be taken into account, in order to optimally control the inputs and outputs of the buffer tank and the heat transfer fluid regeneration unit.

[0011] The technical problem of the invention is therefore to be able to take into account the forecast needs for thermal or cooling energy in order to control an installation optimally, which makes it possible to save energy and to use an installation sized as best as possible according to needs. Statement of the invention

[0012] The present invention aims to address this technical problem by using a device for producing and using a heat transfer fluid in a closed circuit according to operating cycles, the device comprising: - a buffer tank comprising two compartments, a recovery compartment and a storage compartment separated by a flexible membrane, said buffer tank comprising an inlet and an outlet connected to the recovery compartment, and an inlet and an outlet connected to the storage compartment, - a fluid consumption circuit, extending between the outlet of the storage compartment and the inlet of the recovery compartment of the buffer tank, - at least one unit for consuming calories from said heat transfer fluid, configured to extract, for a predetermined duration less than the duration of an operating cycle, calories or frigories from the heat transfer fluid at the level of the consumption fluid circuit, - a regeneration fluid circuit, extending between the outlet of the recovery compartment and the inlet of the storage compartment of the buffer tank, and - at least one controllable heat transfer fluid regeneration unit, configured to supply calories or frigories to the heat transfer fluid at the regeneration fluid circuit.

[0013] This device is particular in that it comprises a control member for said at least one regeneration unit, said control member comprising: - means for recovering a forecast of the energy requirements of said at least one consumption unit over time over the entire duration of an operating cycle; - search means configured to take into account said forecast and determine an optimal control strategy for said regeneration unit in which the regeneration unit provides the required quantity of energy throughout the duration of the operating cycle; the control member being configured to apply said optimal control strategy to said regeneration unit.

[0014] Thanks to these provisions, the regeneration unit can be controlled so as to be able to meet the needs of the consumer unit, while avoiding consuming more energy than necessary. Energy savings are thus achieved compared to existing systems. In addition, the device, and more particularly the power of the regeneration unit, can be precisely sized according to the needs of the consumer unit, which makes it possible to avoid oversizing.

[0015] The search means can be configured to take into consideration an estimate of the heat losses in the consumption fluid circuit when determining the control strategy, which makes it possible to improve the precision of the search for the optimal control strategy.

[0016] Furthermore, the search means can be configured to take into consideration an estimate of the heat losses in the regeneration fluid circuit when determining the control strategy, which also makes it possible to improve the precision of the search for the optimal control strategy.

[0017] The search means can also be configured to take into consideration an estimate of the heat losses in the storage compartment of the buffer tank when determining the control strategy, this estimate taking into account the storage duration of the heat transfer fluid in the storage compartment, which further improves the precision of the search for the optimal control strategy.

[0018] Alternatively or additionally, the search means can be configured to take into consideration a forecast of the evolution of the outside temperature when determining the control strategy, which further improves the precision of the search for the optimal control strategy.

[0019] In the storage compartment, said heat transfer fluid can be in the state of superheated water, which makes it possible to store a large quantity of heat in a restricted volume.

[0020] The buffer tank may comprise two removable shells, and the flexible membrane is fixed between the two shells, which is a simple and effective means of producing a device according to the invention.

[0021] The buffer tank may include at least one position sensor capable of detecting the position of the membrane, which allows more precise control of the device.

[0022] The membrane can be configured so that the volume occupied by each compartment is variable between 10 and 90% of the total volume of the buffer tank, which makes it possible to increase the flexibility of use of the device according to the invention.

[0023] The present invention also relates to a method of using a device according to the invention, comprising an operating cycle comprising the following steps: - heating the heat transfer fluid in the regeneration circuit and storing the heat transfer fluid in the storage compartment, until a target quantity of heat transfer fluid to be stored is reached, this step being carried out over a first period of time; and - sending the heat transfer fluid stored in the storage compartment to the consumption fluid circuit, this step being carried out for a second period of time less than said second period of time.

[0024] Thanks to these provisions, the power required in production can be lower than the power required in consumption, which makes it possible to use a less powerful regeneration unit for identical needs. Brief description of the drawings

[0025] The present invention and its advantages will appear better in the following description of several embodiments given as non-limiting examples, with reference to the appended drawings, in which:

[0026] [Fig-1] [Fig.l] is a schematic view of a device according to a mode of preferred embodiment of the invention,

[0027] [Fig.2] [Fig.2] is a longitudinal sectional view of the buffer tank of a device according to one embodiment of the invention, and

[0028] [Fig.3] [Fig.3] is a cross-sectional view of the buffer tank of [Fig.2], with three different positions of the flexible membrane. Description of the embodiments

[0029] The device according to the invention, illustrated in a preferred embodiment in [Fig.l], makes it possible to produce and use a heat transfer fluid, in a closed circuit, according to operating cycles.

[0030] The heat transfer fluid is for example water, or water mixed with one or more additives, making it possible to modify its thermodynamic properties such as its phase change temperatures and / or its mechanical properties such as its viscosity. The choice of heat transfer fluid depends on the type of application, and in particular the temperatures at which it is used. In the device according to the invention, the fluid heat transfer fluid may be used at constant pressure at any point in the device and not vary with time, or its pressure may vary in different areas of the device and / or with time. The pressure(s) used may be atmospheric pressure, or pressures lower or higher than atmospheric pressure.

[0031] The expression "closed circuit", in the context of the present invention, designates the fact that the majority of the heat transfer fluid regularly flows through the entire circuit. This does not exclude the addition or withdrawal of certain quantities of heat transfer fluid at one or more points in the circuit, to compensate for possible losses, or to adjust the load of heat transfer fluid in the circuit as required.

[0032] The operating cycles of the device according to the invention correspond to cycles of calorie or frigory requirements of the system. These cycles correspond, for example, to the operating cycles of a machine consuming heat or cold, for example a machine requiring a certain quantity of thermal energy every hour for 5 minutes.

[0033] The device according to the invention comprises a buffer tank 1 comprising a recovery compartment 2a, and a storage compartment 2b, separated by a flexible membrane 3.

[0034] The buffer tank 1 comprises a first inlet 4a, and a first outlet 5a, located at the level of the recovery compartment 2a. The first inlet 4a, respectively first outlet 5a, allows heat transfer fluid to pass between the exterior of the buffer tank 1 and the recovery compartment 2a, without passing through the storage compartment 2b.

[0035] Similarly, the buffer tank 1 comprises a second inlet 4b, and a second outlet 5b, located at the level of the storage compartment 2b. The second inlet 4b, respectively second outlet 5b, allows heat transfer fluid to pass between the exterior of the buffer tank 1 and the storage compartment 2b, without passing through the recovery compartment 2a.

[0036] The device according to the invention also comprises a consumption fluid circuit 6, extending between the second outlet 5b and the first inlet 4a, that is to say it is configured to transport the heat transfer fluid, from the storage compartment 2b, to the recovery compartment 2a. At the level of the consumption fluid circuit 6, the device according to the invention comprises at least one consumption unit 7. The consumption unit 7 is configured to extract calories or frigories from the heat transfer fluid, for a predetermined duration less than a duration of an operating cycle. This is for example a heat exchanger, controlled to regularly extract the energy necessary for the operation of a machine, or for maintaining at a certain temperature a space or a tank in which a product to be heated is located.

[0037] The device according to the invention also comprises a regeneration fluid circuit 8, extending between the first outlet 5a and the second inlet 4b, that is to say it is configured to transport the heat transfer fluid, from the recovery compartment 2a, to the storage compartment 2b. At the level of the regeneration fluid circuit 8, the device according to the invention comprises at least one regeneration unit 9. The regeneration unit 9 is configured to provide calories or frigories to the heat transfer fluid, so that they can be extracted by the consumption unit 7. The regeneration unit 9 may be a heat pump, a boiler, or any other means adapted to the particular application to which the invention is put.

[0038] The flexible membrane 3 makes it possible to vary the volumes of the recovery 2a and storage 2b compartments, the sum of these volumes being constant and corresponding to the useful volume of the buffer tank 1. Indeed, during an operating cycle of the device, the latter operating in a closed circuit, the maximum occupation of the recovery 2a compartment, respectively the storage 2b compartment, does not take place at the same time. By taking into consideration the maximum of the sum of the volumes of the two compartments 2a 2b during a cycle, and not the sum of the maximum volumes, it is therefore possible to size the system with a buffer tank 1 of smaller volume.

[0039] The device according to the invention comprises a control member 10 of the regeneration unit 9. In order to optimize the operation of the device, the control member 10 comprises means for recovering a forecast 11 of the energy requirements of the consumption unit 7 over time over the entire duration of an operating cycle. The forecast 11 is for example a computer file in the form of a table, in which, for each subdivision of a cycle, a subdivision corresponding for example to one minute, corresponds to an energy requirement of the consumption unit. These energy requirements can be translated into a supply of heat transfer fluid in the consumption fluid circuit 6 at the level of the consumption unit 7, the heat transfer fluid being brought to a certain temperature and supplied at a certain flow rate.

[0040] The control member can also control one or more valves and / or one or more pumps, located at one location or at different locations of the device according to the invention, for the needs of the application case of the invention.

[0041] For example, we can imagine an operating cycle lasting one hour, in which: - During the first five minutes, consumer unit 7 needs to be supplied with a heat transfer fluid at a temperature of 120°C, at a flow rate of 80 litres per minute, - During the last 55 minutes, consumption unit 7 does not require any energy input.

[0042] From the forecast 11, the control unit 10 uses its search means in order to determine an optimal control strategy for the regeneration unit 9. This optimal control strategy must make it possible to meet the needs listed in the forecast 11 throughout the duration of the operating cycle of the device, while minimizing the energy consumed by the regeneration unit 9.

[0043] In order to improve the accuracy of the search for the optimal strategy, the search means of the control member 10 can take into account certain elements which can influence the temperature of the heat transfer fluid at different locations in the device. It may be chosen to take into account one or more of these elements, individually or in combination, depending on their respective importance in the different cases of use.

[0044] The research means can take into account an estimate of the heat losses in the consumption fluid circuit 6 and / or regeneration 8. These estimates can be determined by calculations, or by one or more test cycles.

[0045] The search means may also take into account an estimate of the heat losses in the storage compartment 2b of the buffer tank 1, this estimate taking into account the storage duration of the heat transfer fluid in the storage compartment 2b. This estimate may be determined by calculations, or by one or more test cycles.

[0046] The research means can also take into account a forecast of the evolution of the outside temperature 1. This forecast can in particular be used to refine the estimates listed above.

[0047] The device according to the invention makes it possible to store a certain quantity of calories or frigories in the storage compartment 2b, for use by the consumption unit 7. The storage compartment 2b being separated from the recovery compartment 2a by the membrane 3, the warm heat transfer fluid coming from the consumption circuit 6 is not mixed with the hot or cold heat transfer fluid coming from the regeneration circuit 9. This makes it possible to optimize the programming of the device. Thus, if, for example, the consumption unit 7 only needs calories or frigories during certain time intervals of the operating cycle of the device, for example 5 minutes every hour, then the rest of the cycle can be used to constitute the necessary energy stock in the storage compartment 2b.The power of the regeneration unit 9 therefore does not need to be sized according to the maximum power of the consumption unit 7. The power of the regeneration unit can be sized according to the power . average of the consumption unit 7 over an operating cycle of the device. This advantage is particularly relevant for heating systems. Indeed, in heating systems of the state of the art, the heat transfer fluid is often used in the vapor state. Since steam is difficult to store, in particular because it occupies a large volume, it is necessary to size the power of the regeneration unit higher than the consumption power, the production having to follow the consumption in real time. In the device according to the invention, the heat transfer fluid of the storage compartment 2b is not, or only very little, mixed with the heat transfer fluid of the recovery compartment 2a.This makes it possible to store the heat transfer fluid in the state of superheated water, the temperature of the heat transfer fluid in the storage compartment 2b being almost equal to the temperature of the heat transfer fluid at the outlet of the regeneration unit 9, and this throughout the consumption of the storage volume 2b, without a thermal mixing front.

[0048] The buffer tank 1 preferably comprises two removable shells, and the flexible membrane 3 is fixed in the buffer tank 1 between the two shells.

[0049] The membrane 3 preferably extends parallel to the largest dimension of the buffer tank 1, in order to limit its movements when the volumes of the compartments 2a, 2b vary.

[0050] The pressure of the two compartments 2a, 2b is preferably equal.

[0051] The membrane 3 is set in motion automatically when the volumes of compartments 2a, 2b, i.e. by the heat transfer fluid inlets and outlets of compartments 2a, 2b. The movements of the membrane 3 allow the volume occupied by each compartment 2a, 2b to be variable, for example between 10 and 90% of the total volume of the buffer tank 1. The movements of the membrane are illustrated by [Fig.3], on which three different positions of the membrane 3A, 3B and 3C are represented.

[0052] As illustrated in [Fig.2], the membrane may for example be connected to the inner surface of the buffer tank 1 by hinges 12. The hinges 12 are preferably fixed to the membrane 13 by means of a fixing plate 13. If the surface of the buffer tank 1 has rounded parts, for example in the case of GRC bottoms, fixed hinge supports 14 may be fixed on these rounded parts. The hinge supports 14 then have a first side 15a, of rounded shape, matching the rounded shape of the inner surface of the buffer tank 1, and a second side 15b, straight, materializing the axis of rotation of the hinges 12, and on which the hinges 12 are fixed.

[0053] The buffer tank 1 is for example a cylindrical tank, closed by two GRC (Large Radius of Carre) bottoms. The buffer tank 1 can then comprise 12 hinges 12, distributed as follows: - four hinges 12 fixed directly to the walls of the cylinder, two of which are on each side of the membrane 3, - eight hinges 12 fixed two by two on four hinge supports 14, two hinge supports 14 being fixed on each GRC bottom.

[0054] The sealing between the recovery compartment 2a and storage compartment 2b may not be complete. In particular, it is possible to ensure that the compartments 2a, 2b communicate, in order to be able to use a common air purge 16 in the upper part of the buffer tank 1, and a common drain purge 17 in the lower part of the buffer tank 1.

[0055] As illustrated in [Fig.3], the buffer tank 1 may comprise at least one position sensor 18 capable of detecting the position of the membrane 3. This makes it possible to estimate the volumes occupied by each compartment 2a, 2b, and this information may be transmitted to the control member 10. Different types of sensor may be used: infrared sensor, inductive sensor, etc. A single sensor 18 may be arranged in the center of the membrane 3, or several sensors 18 may be distributed over the surface of the membrane 3. In order to detect the position of the membrane 3, the buffer tank 1 may comprise a tube 19, passing through the interior of the buffer tank 1 in a direction parallel to the movement of the membrane 3. The tube 19 passes through the membrane, preferably in its center, and the membrane comprises a target arranged close to the tube 19. The position sensor 18, by detecting the position of the target 19, can thus detect the position of the membrane 3. [Fig.3] illustrates this, with the target shown in three different positions 20A, 20B and 20C, corresponding to membrane positions 3A, 3B and 3C.

[0056] The device according to the invention can be used according to a method comprising the following steps: - heating the heat transfer fluid in the regeneration circuit 8 and storing the heat transfer fluid in the storage compartment 2b, until a target quantity of stored heat transfer fluid is reached, corresponding for example to a volume greater than 50% of the buffer tank, this step being carried out over a first period of time, for example greater than 50% of an operating cycle; and - sending the heat transfer fluid stored in the storage compartment 2b to the consumption fluid circuit 6, this step being carried out for a second period of time less than said first period of time, for example less than half of the first period of time.

[0057] The present invention is of course not limited to the embodiments described but extends to any modification and variant obvious to a person skilled in the art within the limits of the appended claims. In addition, the characteristics techniques of the different embodiments and variants mentioned above can be, in whole or in part, combined with each other.

Claims

1. Claims Device for producing and using a heat transfer fluid in a closed circuit according to operating cycles, the device comprising: - a buffer tank (1) comprising two compartments, a recovery compartment (2a) and a storage compartment (2b) separated by a flexible membrane (3), said buffer tank (1) comprising an inlet (4a) and an outlet (5a) connected to the recovery compartment (2a), and an inlet (4b) and an outlet (5b) connected to the storage compartment (2b), - a consumption fluid circuit (6), extending between the outlet (5b) of the storage compartment (2b) and the inlet (4a) of the recovery compartment (2a) of the buffer tank, - at least one consumption unit (7), configured to extract, for a predetermined duration less than the duration of an operating cycle, calories or frigories from the heat transfer fluid at the level of the consumption fluid circuit (6), - a regeneration fluid circuit (8), extending between the outlet (5a) of the recovery compartment (2a) and the inlet (4b) of the storage compartment (2b) of the buffer tank, and - at least one regeneration unit (9) for the heat transfer fluid, configured to provide calories or frigories to the heat transfer fluid at the level of the regeneration fluid circuit (8), characterized in that the device comprises a control member (10) for said at least one regeneration unit (9), said control member (10) comprising: - means for recovering a forecast (11) of the energy requirements of said at least one consumption unit over time over the entire duration of an operating cycle; - search means configured to take into account said forecast (11) and determine an optimal control strategy for said regeneration unit (9) in which the regeneration unit (9) provides the required quantity of energy throughout the duration of the operating cycle; the control member (10) being configured to apply said optimal control strategy to said regeneration unit (9).

2. Device for producing and using a heat transfer fluid according to claim 1, characterized in that the search means are configured to take into consideration an estimate of the heat losses in the consumption fluid circuit (6) when determining the control strategy.

3. Device for producing and using a heat transfer fluid according to one of claims 1 or 2, characterized in that the search means are configured to take into consideration an estimate of the heat losses in the regeneration fluid circuit (8) when determining the control strategy.

4. Device for producing and using a heat transfer fluid according to one of claims 1 to 3, characterized in that the search means are configured to take into consideration an estimate of the heat losses in the storage compartment (2b) of the buffer tank when determining the control strategy, this estimate taking into account the storage duration of the heat transfer fluid in the storage compartment (2b).

5. Device for producing and using a heat transfer fluid according to one of claims 1 to 4, characterized in that the search means are configured to take into consideration a forecast of the evolution of the outside temperature when determining the control strategy.

6. Device for producing and using a heat transfer fluid according to one of claims 1 to 5, characterized in that in the storage compartment (2b), said heat transfer fluid is at least partly in the state of superheated water.

7. Device for producing and using a heat transfer fluid according to one of claims 1 to 6, in which the buffer tank (1) comprises two removable shells, and the flexible membrane (3) is fixed between the two shells.

8. Device for producing and using a heat transfer fluid according to one of claims 1 to 7, in which the buffer tank (1) comprises at least one position sensor capable of detecting the position of the membrane (3).

9. Device for producing and using a heat transfer fluid according to one of claims 1 to 8, in which the membrane (3) is configured so that the volume occupied by each compartment (2a, 2b) either variable between 10 and 90% of the total volume of the buffer tank (1).

10. Method of using a device according to one of claims 1 to 9, comprising an operating cycle comprising the following steps: - heating the heat transfer fluid in the regeneration circuit (8) and storing the heat transfer fluid in the storage compartment (2b), until a target quantity of heat transfer fluid to be stored is reached, this step being carried out over a first period of time; and - sending the heat transfer fluid stored in the storage compartment (2b) to the consumption fluid circuit (6), this step being carried out for a second period of time less than said first period of time.

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