Subcritical cycle carnot battery with heat storage

Abstract

The invention relates to Carnot batteries, and more particularly to those operating with a subcritical cycle. The Carnot battery according to the invention is integrated into a power cycle and comprises a module for converting electrical energy into hot thermal energy, a hot thermal storage module, and an intermediate circuit for discharging the storage module back to the power cycle. The invention optimizes the discharge phase, particularly for subcritical operation. It falls within the corresponding technical fields of electricity storage technologies and systems that increase the flexibility of thermal power plants.

Description

TECHNICAL FIELD

[0001] The present invention relates to Carnot batteries and more particularly those operating with a subcritical cycle.

[0002] It belongs to the technical fields corresponding on the one hand to electricity storage technologies and on the other hand to systems increasing the flexibility of thermal power plants.

[0003] Potential applications include electricity storage linked to a thermal power plant. Another related application is the addition of a Carnot battery to a thermal power plant. STATE OF THE ART

[0004] Carnot batteries (CBs) rely on storing electricity in the form of heat. When a CB stores electricity, it converts it into heat via a charging process and then stores the heat in a thermal storage module. This charging process can typically be a heating element or a heat pump, both of which are electricity-to-heat converters. When the battery is required to release the electricity it has previously stored, the energy stored in the thermal storage module is discharged using a motor cycle. This motor cycle is a symmetrical converter to the charging process, which, in this case, converts heat into electricity. The motor cycle can typically be an organic or non-organic Rankine cycle (ORC) or a Brayton cycle. This type of CB is referred to as an isolated or "standalone" battery in the literature.

[0005] Carnot batteries offer several advantages: firstly, they provide a solution for massive electricity storage. Like all electricity storage technologies, Carnot batteries can also benefit the grid, particularly in terms of stability and flexibility. Secondly, they have few geographical constraints, as their installation requires neither a valley nor a cavern and does not generate any particular hazards in its immediate vicinity.

[0006] However, carbon capture and storage (CCS) technologies face several limitations in their development: this technology has relatively modest conversion efficiencies, ranging from 30% to 60% according to the literature for isolated CCS units. Related to this modest efficiency, the economic viability of projects based on CCS is not always guaranteed. Finally, isolated CCS units suffer from limited responsiveness, inherent to the temperature rise time of the engine cycle and the associated piping during the initiation of the discharge phase.

[0007] Battery cells can be integrated into thermal power plants through various architectures. Two concepts identified to date stand out: one is called coupled batteries (CBB) and the other called grafted batteries (GBB).

[0008] The concept of coupled Carnot batteries is based on an architecture comprising a thermal power plant coupled to a Carnot battery via the charging process and thermal storage. Thus, a portion of the power plant's heat flow is no longer directly converted into electricity by the power cycle, but temporarily stored without any temperature increase. The charging cycle is used either to compensate for some of the storage losses or to increase the amount of stored thermal energy, but always at a uniform temperature between the storage and the power plant's heat source.

[0009] The main advantage of this coupling is the increased flexibility it provides to the power plant. Indeed, the plant operates continuously and, like many thermal power plants, is not easily controllable. This lack of flexibility, given the high variability of electricity demand, can cause grid stability problems. Thus, a coupled storage power plant (SPP) allows, during periods of grid stress, for a portion of electricity production to be curtailed by diverting some of the heat flow to be stored in the SPP. Then, when the grid requires an increase in electricity production again, the SPP can be discharged via its engine cycle, which is shared with the thermal power plant. Therefore, during the discharge phase, the power plant will operate at its nominal capacity, but additional heat from the SPP will be discharged in parallel within the engine cycle.This additional heat discharge from the combined heat and power (CHP) system will result in a surplus of electricity production compared to the power plant's nominal operating capacity. Thus, a CHP system coupled to a power plant provides it with increased flexibility, resulting in a better match between electricity production and demand, through load shedding and subsequent surplus production. In the case of CHP systems, power modulation is therefore achieved by regulating the flow rate of the heat flux sent to the engine cycle.

[0010] Another important characteristic of DCBs is that their operation is linked to that of the thermal power plant. Indeed, for the sharing of the operating cycle between the DCB and the power plant to be feasible, the additional discharge power provided by the DCB must be small relative to the power plant's nominal output. Therefore, the DCB cannot operate independently. For the DCB to charge and discharge, the thermal power plant must be operational.

[0011] The other advantages of implementing this coupling lie primarily in the sharing of the power cycle. This sharing allows, firstly, for a significant reduction in the costs of a DCB compared to an isolated DCB. Secondly, this sharing also significantly increases the DCB's responsiveness. Indeed, unlike isolated DCBs, where the power plant operates continuously, the power cycle is always running. Thus, since the power cycle is always at operating temperature and always running, the effects related to the inertia of starting the power cycle no longer penalize the DCB, resulting in a significant gain in responsiveness. It should also be noted that DCBs, thanks to their improved responsiveness, enable load and frequency monitoring, in addition to the other standard services that storage technologies can provide to the grid.

[0012] The operation and architecture of BCGs are similar to those of BCCs. Their differentiating characteristic lies in the method of utilizing the heat flow from the power plant. In the case of BCCs, the power plant's heat flow is directly integrated into the storage module, whereas for BCGs, it is utilized in the charging process.

[0013] Thus, the diverted heat from the power plant is utilized during the charging of the combined cycle gas turbine (CCGT) and is heated to a higher temperature than that of the power plant before being stored. During discharge, the heat at a higher enthalpy is used in the engine cycle, thereby increasing the enthalpy of the power plant's nominal heat flow. During the discharge phase, since the engine cycle is powered by a higher enthalpy heat flow, the net output of the cycle is increased. Therefore, when the grid is under load and electricity storage is required, a charging phase of the CCGT will be carried out, consuming electricity. This charging phase will store heat at a higher temperature, which will then be discharged when the grid again needs electricity, thereby increasing the net output of the power plant's engine cycle.Conversely, if the BCG has a cold storage, the temperature reached by the charging cycle will be lower than that of the cold source of the motor cycle.

[0014] Here again, the thermal power plant operates continuously. Thus, the major difference between BCCs and BCGs is that the power plant's output modulation is not based on modulating the flow rate through the engine cycle, as in the case of BCCs, but rather on modulating the temperature of the flow through the engine cycle for BCGs. This temperature-based, rather than flow-based, control strategy allows for a different stress to be placed on the turbine, which can be advantageous. Another important characteristic of BCGs is that they cannot operate independently of the power plant, unlike BCCs.

[0015] The advantages of implementing a battery centrifugal charge (BCC) system are quite similar to those of a battery charge controller (BCC). Indeed, for the same reasons as a BCC, a BCC offers significantly better responsiveness than isolated batteries, thus enabling features such as charge or frequency monitoring. Cost reduction is also possible thanks to the shared use of the motor cycle. Finally, BCCs are capable of achieving higher storage efficiencies than conventional batteries without requiring additional external heat sources.

[0016] We also know of patent document FR3060190B1, which describes a Brayton cycle (BC) architecture that increases the flexibility of a Brayton cycle. The BCG includes a cold water storage tank supplied by a refrigeration unit. Discharge of this BCG is ensured by two heat exchangers connected directly to the working fluid circuit of the Brayton cycle.

[0017] These various solutions are well-suited to supercritical and transcritical cycles. However, this entails significant development and infrastructure costs to ensure that the components can be implemented in these demanding cycles, which require high temperatures and pressures.

[0018] Now, with the growing desire to optimize the recovery of waste heat from many industrial processes with temperatures of 300°C or less, there is a need to offer a solution to enable the operation of Carnot batteries, and in particular Grafted Carnot Batteries (BCG) or Coupled Carnot Batteries (BCC), with subcritical cycles at low temperatures, i.e., less than or equal to 300°C. SUMMARY

[0019] To achieve this objective, according to one embodiment, a Carnot battery is planned comprising a power cycle intended to transform thermal energy into electricity comprising an evaporator ensuring heat exchange with a hot source, a turbine and a condenser ensuring heat exchange with a cold source, an electrical energy conversion module into hot thermal energy, and a thermal energy storage module comprising a storage fluid intended to store the hot thermal energy, advantageously produced by the electrical energy conversion module into hot thermal energy, characterized in that it comprises an intermediate circuit ensuring the heat transfer of the hot thermal energy from the storage fluid stored in the thermal energy storage module to the power cycle, the intermediate circuit comprising a discharge heat exchanger ensuring the heat transfer of the hot thermal energy from the storage fluid to the hot source supplying the evaporator of the power cycle. Advantageously, the discharge heat exchanger is arranged upstream of the engine cycle evaporator on a fluidic connection supplying the engine cycle evaporator with a hot source; the discharge heat exchanger includes a hot source inlet and a heated hot source outlet fluidically connected to a hot source inlet of the evaporator by the fluidic connection; the intermediate circuit includes a fluidic connection ensuring the fluidic connection between the storage fluid outlet of the storage module and the storage fluid inlet of the discharge heat exchanger and a fluidic connection ensuring the fluidic connection between the storage fluid outlet of the discharge heat exchanger and the storage fluid inlet of the thermal energy storage module.

[0020] The Carnot battery according to the invention allows for the optimal discharge of stored heat during subcritical cycles. Indeed, the presence of the intermediate circuit with the discharge exchanger, which provides indirect discharge of stored heat to the engine cycle, expands the operating range of Carnot batteries, particularly those grafted onto subcritical cycles. The Carnot battery according to the invention is thus easy to implement thanks to the technological maturity of its components for the low temperatures conducive to subcritical cycles. Furthermore, the infrastructure costs of grafted subcritical Carnot batteries are therefore lower, with significant potential for widespread adoption.

[0021] By introducing the intermediate circuit allowing discharge, it is possible not only to play on the degree of overheating, but also to play on the high pressure of the engine cycle, which leads to much higher restitution ratios and suggests an economic reality for the system.

[0022] Indeed, the architectures adapted to transcritical and supercritical cycles known today in the literature do not allow for an increase in the high pressure of the engine cycle. However, in subcritical cycles, the direct discharge of the BCG via a heat exchanger in series with the engine cycle evaporator leads only to an increase in superheat.

[0023] However, an increase in superheating only results in a very slight increase in turbine performance and therefore leads to a very small increase in electricity production for subcritical cycles. This small increase in production, compared to the energy removed during charging and that consumed by the conversion module, results in a low return on investment for the Carnot battery, demonstrating the limited economic viability of such a system.

[0024] The advantage of the present invention is therefore to overcome the problem of only adding superheat to the fluid by the BCG.

[0025] Furthermore, lowering the operating temperature of the Carnot battery also reduces losses during the storage phase, thus improving the profitability of subcritical Carnot batteries.

[0026] The invention thus improves the controllability and flexibility of thermal power plants. The storage system linked to the power plant provides increased stability for the grid, and also enables load and frequency monitoring, as well as energy arbitrage, for the operator.

[0027] Following another aspect, the invention relates to a method for producing electrical energy by a Carnot battery as described above, comprising a charging stage including heat exchange in the engine cycle evaporator between the heat source and an engine fluid circulating in the engine cycle to ensure the evaporation of the engine fluid, expansion of the engine fluid from the evaporator in the engine cycle turbine enabling the production of electricity by an associated generator, heat exchange in the engine cycle condenser between the cold source and the engine fluid to ensure the condensation of the engine fluid, production of hot thermal energy by the conversion module and storage of the hot thermal energy in the storage module. BRIEF DESCRIPTION OF THE FIGURES

[0028] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which: There figure 1represents a schematic diagram of the Carnot battery according to the invention. figure 2 This represents a schematic diagram of the Carnot battery during a stationary phase. figure 3 This represents a schematic diagram of the Carnot battery during a charging phase. figure 4 represents a schematic diagram of the Carnot battery during a discharge phase.

[0029] The drawings are given as examples and are not limiting to the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. DETAILED DESCRIPTION

[0030] Before beginning a detailed review of embodiments of the invention, optional features which may possibly be used in association or alternatively are stated below: According to an example, the electrical energy conversion module into hot thermal energy is a heat pump 1100 comprising an evaporator 1104 supplied by the hot source 6, and arranged in series and upstream of the discharge heat exchanger 1002.

[0031] As an example, the conversion module is a heating element.

[0032] According to one example, the Carnot battery includes a recuperator 203 arranged on the engine cycle 200 to ensure heat exchange between a fluid connection linking the downstream of the turbine 201 to the upstream of the condenser 204 and a fluid connection linking the downstream of the pump 205 to the upstream of the evaporator 202.

[0033] According to one example, the process includes a hot thermal energy discharge step comprising, a release of the heat transfer fluid from the storage module 1003, a heat exchange in the discharge heat exchanger 1002 between the released heat transfer fluid from the storage module 1003 and the hot source 6 to increase the temperature of the hot source 6, a heat exchange in the evaporator 202 of the engine cycle 200 between the heated hot source 6 and the engine fluid allowing the evaporation of the engine fluid.

[0034] According to one example, the hot thermal energy discharge stage includes an expansion of the working fluid from the evaporator 202 in the turbine 201 of the engine cycle 200 enabling the production of electricity by an associated generator 206.

[0035] According to one example, the conversion module is a heat pump 1100 in which the hot source 6 circulates in the evaporator 1104 of the heat pump 1500 upstream and in series with the evaporator 202 of the motor cycle 200.

[0036] According to one example, the process includes a stationary operating step comprising a heat exchange in the evaporator 202 of the motor cycle 200 between the heat source 6 and a motor fluid circulating in the motor cycle (200) to ensure the evaporation of the motor fluid, an expansion of the motor fluid from the evaporator 202 in the turbine 201 of the motor cycle 200 enabling the production of electricity by an associated generator 206, a heat exchange in the condenser 204 of the motor cycle 200 between the cold source 5 and the motor fluid to ensure the condensation of the motor fluid.

[0037] Upstream and downstream, inlet and outlet, at a given point are taken in reference to the direction of fluid flow.

[0038] A parameter "approximately equal to / greater than / less than" or "of the order of" a given value means that this parameter is equal to / greater than / less than the given value, to within 10% or even 5% of that value.

[0039] For the purposes of this disclosure, "A and / or B" means (A), (B), or (A and B). For the purposes of this disclosure, "A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0040] Supercritical means that the Carnot battery according to the invention operates at pressure and temperature levels above the critical point of the circulating working fluid.

[0041] Transcritical means that the Carnot battery according to the invention operates at pressure and temperature levels above and below the critical point of the circulating working fluid.

[0042] Subcritical means that the Carnot battery according to the invention operates at pressure and temperature levels below the critical point of the circulating working fluid.

[0043] Fluidically connected or in fluidic connection means when a line provides a connection through or in which a fluid flows.

[0044] In this description, the expression "A fluidly connected to B" is synonymous with "A is in fluidic connection with B" and does not necessarily mean that there is no organ between A and B. The expressions "arranged on" or "on" are synonymous with "fluidly connected to".

[0045] The expression "A fluidically connected to B" or "A fluidically connected to B" is synonymous with "A is in fluidic connection with B" and does not necessarily mean that there is no component between A and B. Thus, these expressions refer to a fluidic connection between two elements, which may or may not be direct. This means that it is possible for a fluid to flow between a first element and a second element that are fluidically connected, through one or more conduits or connections, possibly including an additional component.

[0046] Conversely, the term "fluidically connected directly" refers to a direct fluidic connection between two elements. This means that between a first element and a second element that are fluidly connected directly, no other element is present, other than one or more conduits / connections / channels.

[0047] Hot, cold, cooled refers to a relative temperature compared to another point in the system.

[0048] The terms "first", "second" and "third", "additional", etc. are used simply as labels, and are not intended to impose numerical requirements on their objects.

[0049] The invention relates to a Carnot battery grafted to a thermal power plant, based on an engine cycle operating advantageously in subcritical mode.

[0050] The Carnot battery according to the invention comprises a thermal power plant for converting thermal energy into electricity. In this application, the terms power plant, generating plant, and thermal power plant are used interchangeably to define the thermal power plant.

[0051] Thermal power plants can be of various types. A thermal power plant includes a heat source 6, which can be of diverse nature, for example, geothermal, biomass, fossil fuels, solar, nuclear, or waste heat. The thermal power plant includes an engine cycle 200 that transforms the heat source 6 into electrical energy. For example, the heat source 6 has a temperature between 80 and 800°C.

[0052] The Carnot battery thus comprises a power cycle 200 designed to transform thermal energy, from a hot source 6, into electricity. The power cycle 200 includes at least one evaporator 202, a turbine 201 and a condenser 204.

[0053] The motor cycle 200 is for example a Brayton cycle or a Rankine cycle or an organic Rankine cycle.

[0054] The 200 engine cycle includes a fluidic circuit receiving an engine fluid and intended to connect the various components of the 200 engine cycle fluidically.

[0055] The evaporator 202 is configured to ensure heat exchange between the engine cycle 200 and the hot source 6. The function of the evaporator 202 is to ensure the evaporation of the engine fluid through the supply of hot thermal energy by the hot source 6.

[0056] The turbine 201 of the engine cycle is configured to ensure the expansion of the engine fluid to drive the turbine 201. Advantageously, the turbine 201 is associated with a generator 206. The generator 206 is set in motion by the turbine 201 during the expansion of the engine fluid and thus ensures the production of electricity.

[0057] For example, turbine 201 is an axial turbomachine. The present invention remains functional for any type of expansion turbine, whether axial, centripetal or hybrid, a positive displacement machine of the scroll, piston, screw type, etc.

[0058] The condenser 204 of the engine cycle is configured to ensure heat exchange between the engine cycle and a cold source 5. The condenser 204 has the function of ensuring the condensation of the engine fluid through cooling achieved by the supply of cold thermal energy from the cold source 5.

[0059] Advantageously, the engine cycle includes a pump 205 intended to move the engine fluid in the fluidic circuit of the engine cycle.

[0060] According to an advantageous embodiment, the engine cycle 200 includes a first heat exchanger 203 arranged between the outlet of the turbine 201 and the outlet of the pump 205. The first heat exchanger 203 is intended to ensure heat exchange between the engine fluid at the outlet of the turbine 201 and the engine fluid at the outlet of the pump 205. The engine fluid at the outlet of the turbine 201 transfers thermal energy to the engine fluid at the outlet of the pump 205, allowing preheating of the engine fluid before its entry into the evaporator 202 and cooling of the engine fluid before its entry into the condenser 204.

[0061] According to a preferred possibility, the fluidic circuit of the motor cycle 200 ensures the successive fluidic connection of the evaporator 202 connected fluidly, preferably directly, to the turbine 201, then the turbine 201 is connected fluidly to the condenser 204, preferably via the first recuperator 203, then the condenser 204 is connected fluidly, preferably directly, to the pump 205, then the pump 205 is connected fluidly to the evaporator 202, preferably via the first recuperator of 203.

[0062] According to the illustrated embodiment, engine cycle 200 is an organic Rankine cycle. As such, the working fluid circulating in engine cycle 200 is an organic fluid such as Novec649.

[0063] According to the invention, the Carnot battery includes a module for converting electrical energy into hot thermal energy.

[0064] In one scenario, the conversion module is, for example, a heating element. The heating element is designed to heat a fluid, preferably a storage fluid intended for storage in a storage module 1003.

[0065] According to another possibility, the conversion module is a heat pump 1100 intended to convert electrical energy into hot thermal energy intended to be stored in a storage module 1003.

[0066] As an example, the heat pump 1100 includes a circuit designed to receive a heat transfer fluid and ensuring the fluidic connection of the heat pump components. The heat pump 1100 comprises a compressor 1101, an evaporator 1104, an expansion valve 1103, and a condenser 1102. The compressor 1101 is fluidly connected, preferably directly, to the evaporator 1104, then the evaporator 1104 is fluidly connected, preferably directly, to the expansion valve 1103, then the expansion valve 1103 is fluidly connected, preferably directly, to the condenser 1102, and finally the condenser 1102 to the compressor 1101.

[0067] The condenser 1102 is designed to ensure heat exchange between a hot source 6 and the heat transfer fluid in order to condense the heat transfer fluid.

[0068] Hot spring 6 is, for example, water in a water network, river water, etc. Preferably, the temperature of the hot spring is between 80 and 300°C.

[0069] According to one possibility, the evaporator 1102 of the heat pump 1100 is supplied by a different hot source than the hot source 6 supplying the evaporator 202 of the engine cycle 200. This possibility allows the charging of the Carnot battery to be decoupled from the operation of the engine cycle. No reduction in electricity production is observed during charging, and the engine cycle operates nominally while the Carnot battery is being charged.

[0070] According to another possibility, the evaporator 1102 of the heat pump 1100 is supplied by the hot source 6 which supplies the evaporator 202 of the motor cycle 200. According to this possibility, the hot source 6 successively supplies, following the flow of the hot source 6, the evaporator 1104 of the heat pump, then the discharge heat exchanger 1002 of the intermediate circuit 1, then the evaporator 202 of the motor cycle 200. Advantageously, the fluid connection F is a supply line from the hot source 6 successively supplying the discharge heat exchanger 1003 and then the evaporator 202 of the motor cycle. Preferably, bypass fluid connections O and N are connected via a tap on the fluid connection F upstream of the discharge heat exchanger 1002 to supply in parallel, the evaporator 1102 of the heat pump 1100.

[0071] Thus, rather than the heat source of the heat pump 1100 using the ambient temperature, it is advantageous to connect it to the heat flow of the heat source 6 of the engine cycle 200. The heat pump will therefore extract heat from the heat flow of the heat source 6 of the engine cycle 200 at its evaporator 1102, transferring it to the storage module 1003 via its condenser 1004. This operation, which consumes electricity, also implies a decrease in the heat available at the evaporator 202 of the engine cycle 200, and therefore a reduction in the latter's electrical output. During the charging phase, the Carnot battery according to the invention causes a reduction in electrical output, while simultaneously drawing power from the grid to power its compressor.

[0072] Using a heating element as a conversion module simplifies the operation of the Carnot battery by decoupling the charging process from the engine cycle. During charging, the engine cycle behaves according to its nominal operating parameters, and no reduction in electricity production occurs. Using a heating element instead of a heat pump increases the system's reliability and reduces maintenance.

[0073] According to the invention, the Carnot battery comprises a thermal storage module 1003 containing a storage fluid for storing hot thermal energy, preferably produced by the electrical-to-thermal-energy conversion module, and advantageously produced by the heat pump. The thermal storage module 1003 is, for example, a storage fluid reservoir, advantageously thermally insulated from the environment.

[0074] As a preferred example, the storage fluid is water. As an example, the storage fluid stored in the thermal storage module is at a temperature between 100°C and 800°C.

[0075] The evaporator 1104 of the heat pump 1100 is intended to ensure heat exchange between the heat transfer fluid of the heat pump 1100 and the storage fluid of the thermal storage module 1003 so as to ensure the evaporation of the heat transfer fluid and to cool the storage fluid of the thermal storage module 3100.

[0076] For example, the 1100 heat pump operates in a subcritical cycle. The 1100 heat pump cycle can also be transcritical or supercritical, depending on the heat transfer fluid and the desired temperature levels. For example, the heat transfer fluid is cyclopentane.

[0077] According to the invention, the Carnot battery includes an intermediate circuit 1001 ensuring the heat transfer of hot thermal energy from the storage fluid stored in the energy storage module 1003 to the engine cycle 200. The intermediate circuit 1001, called the intermediate discharge circuit, includes a discharge heat exchanger 1002 ensuring the heat transfer between the heat transfer fluid and a hot source 6 supplying the evaporator 202 of the engine cycle 200.

[0078] Preferably, the intermediate circuit 1001 includes a pump 1004 for circulating the storage fluid between the storage module 1003 and the discharge heat exchanger 1002.

[0079] The intermediate circuit 1001 is designed to receive a heat transfer fluid and ensure the fluidic connection of the intermediate circuit components. The intermediate circuit 1001 includes the discharge heat exchanger 1002, the storage module 1003, and optionally the pump 1004. The discharge heat exchanger 1002 is fluidly connected, preferably directly, to the pump 1004, then the pump 1004 is fluidly connected, preferably directly, to the thermal storage module 1003, and finally the thermal storage module 1003 is fluidly connected, preferably directly, to the discharge heat exchanger 1002.

[0080] The intermediate circuit 1001 is a fluid loop comprising fluid connections ensuring the series fluid connection of the thermal energy storage module 1003 and the discharge heat exchanger 1002. The intermediate circuit 1001 includes a fluid connection P ensuring the fluid connection from the storage fluid outlet of the storage module 1003 to the storage fluid inlet of the discharge heat exchanger 1002. The intermediate circuit 1001 includes a fluid connection Q ensuring the fluid connection from the storage fluid outlet of the discharge heat exchanger 1002 to the storage fluid inlet of the storage module 1003. Preferably, the pump 1004 is arranged on the fluid connection Q.

[0081] The discharge heat exchanger 1002 is separate from the evaporator 202 of the engine cycle.

[0082] The architecture of the Carnot battery according to the invention optimizes the discharge phase. Indeed, after being previously charged via the heat pump 1100, the storage module 1003 is discharged via the intermediate circuit 1001 onto the hot source circuit 6.

[0083] Indeed, the presence of intermediate circuit 1001 ensures optimal discharge of the Carnot battery, particularly for subcritical cycles.

[0084] In one aspect, the Carnot battery comprises a control module with multiple valves to control the flow of the working fluid in the fluid circuits and multiple sensors to measure predefined parameters in the fluid circuits. The operation of the Carnot battery involves measuring predefined parameters in the fluid circuits using sensors, comparing the measurements with predefined values, and initiating the various operating phases of the battery.

[0085] The motor cycle circuit 200, the intermediate circuit 1001 and the conversion module circuit 1100 are separate, i.e. they are not in fluidic connection.

[0086] The architecture of a Carnot battery according to an example of the invention as illustrated in the figure 1 is detailed below.

[0087] In the engine cycle 200, the hot source 6 is fluidically connected to the evaporator 202 of the engine cycle 200. The hot source 6 is fluidically connected, preferably directly, to the inlet of the hot source of the evaporator 202 via a fluid connection F. An outlet of the hot source of the evaporator 202 is fluidly connected to the outlet of the hot source 6 via a fluid connection G. Advantageously, the pump 11 is arranged on the fluid connection G.

[0088] At the heat pump 1100, the evaporator 1102 includes a hot source inlet and a hot source outlet. The hot source inlet of the evaporator 1102 is fluidically connected, preferably directly, to the hot source 6 supplying the evaporator 202 of the motor cycle 200 via a fluid connection N. The hot source outlet of the evaporator 1102 is fluidly connected, preferably directly, to the hot source 6 supplying the evaporator 202 of the motor cycle 200 via a fluid connection O. The fluid connection N is, for example, a branch made on the fluid connection F upstream of a branch made on the fluid connection M for the fluid connection O.

[0089] At the intermediate circuit 1001, the discharge heat exchanger 1002 includes a hot source inlet and outlet 6, the hot source inlet 6 of the discharge exchanger 2 is connected to the fluidic connection F allowing the arrival of the hot source in the Carnot battery, the hot source outlet of the discharge exchanger 1002 is fluidically connected to the hot source inlet of the evaporator 202 by the fluidic connection F, preferably directly.

[0090] The storage module 1003 includes a stored storage fluid outlet fluidically connected to the storage fluid inlet of the discharge heat exchanger 1002 by the fluidic connection P. Advantageously, a pump 1004 is arranged on the fluidic connection P. The discharge heat exchanger 1002 includes a storage fluid outlet fluidly connected to the inlet of the storage module 1003 by the fluidic connection Q.

[0091] At the engine cycle 200, the evaporator 202 includes an inlet and an outlet for the engine fluid. The engine fluid outlet of the evaporator 202 is fluidically connected, preferably directly, to the inlet of the turbine 201 via a fluid connection H. The engine fluid inlet of the evaporator 202 is fluidly connected to a second outlet of the recuperator 203, if present, via the fluid connection L; otherwise, to the pump 5; otherwise, to the condenser 204.

[0092] The turbine 201 includes an inlet and an outlet of motive fluid. The outlet of motive fluid of the turbine 201 is fluidically connected to the inlet of the condenser 204, preferably the outlet of the turbine 201 is fluidically connected directly to a first inlet of the recuperator 203 by the fluidic connection I, a first outlet of the recuperator 203 being fluidically connected directly to the inlet of motive fluid of the condenser 204 by the fluidic connection J.

[0093] The condenser 204 includes a working fluid inlet and outlet. The working fluid outlet of the condenser 204 is fluidically connected to a second inlet of the recuperator 203 via the fluid connection K. Advantageously, the pump 205 is arranged on the fluid connection K, advantageously downstream of the condenser 204 and upstream of the recuperator 203, if present, or otherwise upstream of the evaporator 202.

[0094] The condenser 204 includes a cold source inlet 5 fluidically connected to the cold source inlet in the Carnot battery by the fluidic connection M.

[0095] The condenser 204 includes a cold source outlet 5 fluidly connected to the cold source outlet out of the Carnot battery by the fluidic connection E.

[0096] The Carnot battery according to the invention operates in 3 phases, including a stationary phase corresponding to the operation of transforming thermal energy into electrical energy, a charging phase corresponding to the operation of storing thermal energy and a discharging phase corresponding to the operation of releasing thermal energy.

[0097] In the stationary phase, the Carnot battery according to the invention operates as illustrated in the figure 2 detailed below.

[0098] The hot source 6, the motor cycle 100, and the cold source supply to the condenser 204 are active in the steady-state phase. Active means that fluid circulation is occurring. In the steady-state phase, the heat pump 1100 and the intermediate circuit 1001, which provides heat exchange between the storage module 1003 and the motor cycle 200, are not active; that is, there is no fluid circulation.

[0099] The stationary phase will be described below from an operational point of view.

[0100] The hot source 6 supplies the evaporator 202 of the motor cycle 200.

[0101] The hot source 6 enters the evaporator 202 at a temperature higher than its temperature upon exiting the evaporator 202. The hot source 6, which is neither supplied nor cooled by the storage module 1003, transfers its thermal energy to the drive cycle 200 via the evaporator 202. The drive cycle 200 generates electrical energy through its turbine 201 connected to the generator 206. The condenser 204 is supplied by the cold source 5 from the environment. The refrigeration unit 100 is not operating; there is no production of cold or storage of cold in the storage module 3. There is no release of cold from the storage module. The stationary phase is an operating mode corresponding to a simple energy conversion.

[0102] The charging phase of the Carnot battery is intended for the conversion of electricity from a hot source 6 via the heat pump 1100.

[0103] During the charging phase, the Carnot battery according to the invention is illustrated in the figure 3 detailed below.

[0104] The hot source 6, the motor cycle 200, the heat pump 1100, and the cold source supply to the condenser 204 are active during the charging phase. "Active" means that fluid circulation is occurring. The intermediate circuit 1001, which provides heat exchange between the storage module 1003 and the motor cycle 200, is not active; that is, there is no fluid circulation.

[0105] During the charging phase, the operation of the Carnot battery according to the invention is identical to its operation during the stationary phase, with the addition of the operation of the 1100 heat pump, which allows for the storage of electrical energy in the form of hot thermal energy. This charging phase is implemented when there is a surplus of electrical energy relative to the demand on the grid. The Carnot battery according to the invention thus allows for the storage of surplus electrical energy in the form of hot thermal energy.

[0106] The discharge phase of the Carnot battery is intended for the transmission of thermal energy previously stored in the thermal storage module 1003 to the engine cycle 200.

[0107] During the discharge phase, the Carnot battery according to the invention is illustrated in the figure 4 detailed below.

[0108] The hot source 6, the motor cycle 200, the intermediate circuit 1001, and the cold source supply to the condenser 204 are active during the discharge phase. "Active" means that fluid circulation is occurring. The heat pump 1100 is not active; that is, there is no fluid circulation.

[0109] During discharge, the operation of the Carnot battery according to the invention is identical to the operation in the stationary phase with the addition of the operation of the intermediate circuit 1001 which allows the release of the hot thermal energy stored in the storage module 1003 to the engine cycle 200.

[0110] The storage fluid stored in the storage module 1003 is discharged to the discharge heat exchanger 1002 which allows the transfer of thermal energy from the stored storage fluid to the hot source 6, which then supplies the evaporator 202 of the engine cycle 200. The storage fluid returns to the storage module 1003 at a lower temperature than that at which it left.

[0111] Thus, the discharge heat exchanger 1002, through sensible heat transfer only, increases the temperature of the hot source 6 of the engine cycle 200. The heated hot source 6 therefore enters the engine cycle evaporator 202 at a higher temperature than during the stationary, or nominal, operation of the Carnot battery. The temperature of the hot source 6 entering the evaporator 202 results from the heat input from the storage module 1003 at the nominal heat flux of the hot source 6. Since the profile of the hot source 6 at the evaporator 202 is higher, this allows for a higher evaporation pressure of the engine fluid than during the nominal operation of the Carnot battery. This increase in high pressure resulting from the discharge of the storage module 1003 is advantageous because the better the pressure ratio between the upstream and downstream sides of the turbine 201, the better its performance.Thus, the increase in high pressure due to the discharge of the storage module 1003 allows a notable increase in the electrical production of the motor cycle 200, which is therefore sought in the context of the operation of a Carnot battery according to the invention. Example

[0112] A Carnot battery according to the invention was simulated using EES (Engineering Equations Solver) software.

[0113] Regarding the thermal power plant, its nature, flow rate, and temperature can be arbitrary; however, typical temperature and power assumptions have been adopted. Thus, the hot source 6 of the plant has been modeled as a heat source at a constant temperature of 130°C, delivering a maximum power of 80 kW, also constant over time. The profile of this hot source 6 is left as a degree of freedom. The cold source 5 is considered to have a constant temperature of 13°C, but with infinite power and flow rate. The profile of this cold source 5 is also a degree of freedom. The assumption of infinite power and flow rate models a thermal power plant whose cold source 5 would be provided by a stream or reservoir with a limited and constant temperature, but with an available flow rate an order of magnitude greater than the plant's requirements.

[0114] The component efficiencies were assumed to be constant and are taken from the literature. The adopted efficiency values ​​are given below: Turbine 201 isentropic: 0.75 Generator 206: 0.95 Pumps 4, 205, 11: 0.5 Compressor 101 isentropic: 0.9

[0115] Losses during storage were neglected and a constant pinch was adopted for the various BCG exchangers.

[0116] The performance data for the Carnot battery according to the invention are provided below: Grafting rate: 10% Load / discharge ratio: 100% Motor cycle efficiency during the stationary phase: 13.2% Motor cycle efficiency during the loading phase: 12.8% Motor cycle efficiency during the discharging phase: 13.6% BCG recovery ratio: 80.1%

[0117] The degree of integration is an indicator used to obtain information about battery size. Battery size is considered here relative to the services it can provide to the grid in terms of power modulation of the thermal power plant's output. Here, the simulated Carnot battery has a degree of integration of approximately 10%, meaning it will be able to modulate the engine cycle power, during discharge, by 10% of the nominal output. The simulated Carnot battery is therefore of sufficient size to provide services to the grid.

[0118] The charge / discharge ratio is set to 100%, meaning that the charge phase is of the same duration as the discharge phase.

[0119] The Carnot battery restitution ratio here is 80.1%, which means that 80.1% of the electricity that was erased and consumed during charging (i.e., stored in the Carnot battery) was restored during the discharge of the Carnot battery.

[0120] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention. LIST OF REFERENCES

[0121] 5. Cold source 6. Hot source 11. Hot source pump 1001. Intermediate circuit 1002. Discharge exchanger 1003. Storage module 1004. Discharge pump 1100. Heat pump 1101. Compressor 1102. Condenser 1103. Expansion valve 1104. Evaporator 200. Motor cycle 201. Turbine 202. Evaporator 203. Heat exchanger 204. Condenser 205. Pump 206. Generator E. Return line from the cold source of the motor cycle to the condenser F. Fluid connection between the hot source and the evaporator of the motor cycle G. Fluid connection between the evaporator of the motor cycle and the hot source H. Fluid connection between the evaporator of the motor cycle and the turbine I. Fluid connection between the turbine and the heat exchanger of the motor cycle J. Fluid connection between the heat exchanger of the cycle engine and engine cycle condenser K. fluidic connection between the engine cycle condenser and the engine cycle recuperator L.Fluid connection between the engine cycle recuperator and the engine cycle evaporator M. Supply line from the engine cycle cold source to the engine cycle condenser N. Fluid connection between the heat source and the heat pump evaporator O. Fluid connection between the heat pump evaporator and the heat source P. Fluid connection between the outlet of the heat storage module and the inlet of the intermediate circuit discharge exchanger Q. Fluid connection between the outlet of the intermediate circuit discharge exchanger and the inlet of the heat storage module.

Claims

1. Carnot battery comprising a power cycle (200) for converting thermal energy into electricity, including an evaporator (202) providing heat exchange with a hot source (6), a turbine (201) and a condenser (204) providing heat exchange with a cold source (5), a module for converting electrical energy into hot thermal energy, and a thermal energy storage module (1003) comprising a storage fluid for storing the hot thermal energy produced by the module for converting electrical energy into hot thermal energy. characterized in thatIt includes an intermediate circuit (1001) ensuring the heat transfer of hot thermal energy from the storage fluid stored in the thermal energy storage module (1003) to the engine cycle (200). The intermediate circuit (1001) includes a discharge heat exchanger (1002) ensuring the heat transfer of hot thermal energy from the storage fluid to the hot source (6) supplying the evaporator (202) of the engine cycle (200). The discharge heat exchanger (1002) is arranged upstream of the evaporator (202) of the engine cycle on a fluidic connection (F) supplying the evaporator (202) of the engine cycle (200) with a hot source (6). The discharge heat exchanger (1002) includes a hot source inlet (6) and a heated hot source outlet (6) fluidically connected to a hot source inlet of the evaporator (202) by the fluidic connection. (F),The intermediate circuit (1001) includes a fluid connection (P) ensuring the fluid connection between the storage fluid outlet of the storage module (1003) and the storage fluid inlet of the discharge heat exchanger (1002), and a fluid connection (Q) ensuring the fluid connection between the storage fluid outlet of the discharge heat exchanger (1002) and the storage fluid inlet of the thermal energy storage module (1003).

2. Carnot battery according to the preceding claim in which the electrical energy conversion module into hot thermal energy is a heat pump (1100) comprising an evaporator (1104) supplied by the hot source (6), and arranged in series and upstream of the discharge heat exchanger (1002).

3. Carnot battery according to claim 1 wherein the conversion module is a heating resistor.

4. Carnot battery according to any one of the preceding claims comprising a recuperator (203) arranged on the engine cycle (200) to ensure heat exchange between a fluid connection linking the downstream of the turbine (201) to the upstream of the condenser (204) and a fluid connection linking the downstream of the pump (205) to the upstream of the evaporator (202).

5. A method for producing electrical energy by a Carnot battery according to any one of the preceding claims comprising a hot thermal energy discharge stage including, a release of the heat transfer fluid from the storage module (1003), a heat exchange in the discharge heat exchanger (1002) between the released heat transfer fluid from the storage module (1003) and the hot source (6) to increase the temperature of the hot source (6), a heat exchange in the evaporator (202) of the engine cycle (200) between the heated hot source (6) and the engine fluid allowing the evaporation of the engine fluid.

6. Method of producing electrical energy according to the preceding claim comprising a charging stage including a heat exchange in the evaporator (202) of the engine cycle (200) between the heat source (6) and an engine fluid circulating in the engine cycle (200) to ensure the evaporation of the engine fluid, an expansion of the engine fluid from the evaporator (202) in the turbine of the engine cycle (200) enabling the production of electricity by an associated generator (206), a heat exchange in the condenser (204) of the engine cycle (200) between the cold source (5) and the engine fluid to ensure the condensation of the engine fluid; a production of hot thermal energy by the conversion module and the storage of the hot thermal energy in the storage module (1003).

7. A method for producing electrical energy according to any one of the two preceding claims, wherein the hot thermal energy discharge step includes an expansion of the motive fluid from the evaporator (202) in the turbine (201) of the motor cycle (200) enabling the production of electricity by an associated generator (206).

8. Method of producing electrical energy according to the preceding claim in which the conversion module is a heat pump (1100) in which the hot source (6) circulates in the evaporator (1104) of the heat pump (1100) upstream and in series with the evaporator (202) of the motor cycle (200).

9. A method for producing electrical energy according to any one of the four preceding claims comprising a stationary operating step including a heat exchange in the evaporator (202) of the engine cycle (200) between the heat source (6) and an engine fluid circulating in the engine cycle (200) to ensure the evaporation of the engine fluid, an expansion of the engine fluid from the evaporator (202) in the turbine (201) of the engine cycle (200) enabling the production of electricity by an associated generator (206), a heat exchange in the condenser (204) of the engine cycle (200) between the cold source (5) and the engine fluid to ensure the condensation of the engine fluid.

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