EP3438422B1 - Device and method for regulating the fluid load circulating in a system based on a rankine cycle - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a system for producing electrical or mechanical energy and a method for regulating the fluid charge circulating in the fluid circuit of such a system.

Its advantageous application is low power energy production systems, using a Rankine thermodynamic cycle. It will apply, for example, to the production of energy from low-temperature thermal discharges produced by factories, particularly in the processing industry (metallurgy, chemistry, papermaking), by thermal engines of vehicles or from heat from systems recovering solar energy or from biomass.

The present invention will find application particularly for the thermal management of on-board systems, of low power or presenting strong variations in power over time.

STATE OF THE TECHNIQUE

There are many solutions for producing electricity or mechanical energy from a heat source.

Among the known solutions are generating machines based on a Rankine cycle. Rankine cycles are all based on transformations including successively: the pumping of a working fluid in liquid form, the creation of steam and its eventual overheating, the expansion of the steam to generate movement and the condensation of the steam. The working fluid can be chosen from water, carbon dioxide, ammonia or an organic fluid or a mixture of these components. In the last case, we speak of the organic Rankine cycle. The majority of thermal electricity production systems are based on the use of such cycles.

• une pompe permettant la mise en circulation du fluide et la remontée de sa pression ;
• un échangeur chaud exploitant la source de chaleur disponible à valoriser ;
• un expanseur ou organe de détente transformant la variation d'enthalpie du fluide en énergie mécanique, puis en énergie électrique en présence d'une génératrice également désignée alternateur ;
• un échangeur froid permettant la condensation de la vapeur restante après détente.

A machine based on a Rankine cycle is, in a known manner, made up of four main organs, namely:

• a pump allowing the circulation of the fluid and the rise in its pressure;
• a hot exchanger using the available heat source to be recovered;
• an expander or expansion member transforming the variation in enthalpy of the fluid into mechanical energy, then into electrical energy in the presence of a generator also called an alternator;
• a cold exchanger allowing the condensation of the remaining steam after expansion.

It is on this type of thermodynamic cycle that the majority of nuclear power plants, coal-fired thermal power plants, or even heavy fuel oil thermal power plants are based, in order to produce high powers. For these applications, hot springs have very high power and temperature.

Processing industries, for example metallurgy, chemistry or even papermaking, generate low-temperature thermal discharges, that is to say thermal discharges whose temperature is most often below 200°C, or even lower at 150°C. Systems based on a Rankine cycle would theoretically make it possible to produce electrical or mechanical energy from these thermal releases. However, the powers that could be produced would then be relatively low, typically of the order of a few kilowatts to a hundred kilowatts for thermal discharges of less than a megawatt, because of the low thermodynamic efficiency.

At these temperature and power levels, there is currently no truly satisfactory recovery solution, due to the necessary investments and conversion yields which are not considered sufficient.

These low-temperature thermal releases are then in practice little exploited and valorized. The same goes for the heat produced by the thermal engines of land or water vehicles.

In order to maximize the net power and efficiency of a Rankine machine, it is useful to lower the condensing pressure as much as possible. However, to ensure the proper functioning of the pumping member, the fluid must enter the pump in a sub-cooled liquid state.

Subcooling which corresponds to the difference between the pump inlet temperature and the saturation temperature of the fluid is called subcooling. Too much subcooling indicates that there is too much liquid in the condenser, which leads to a degradation of the performance of the Rankine machine by increasing the condensation pressure. Conversely, insufficient subcooling leads to a risk of cavitation at the pump inlet and therefore a deterioration in the performance of the Rankine machine as well as accelerated wear of the pump.

Cavitation appears when the pumped liquid vaporizes at low pressure. This occurs due to insufficient pressure at the pump inlet relative to the saturation pressure of the fluid, in other words, when there is a NPSHa (Net positive Suction Head available), or margin of cavitation, insufficient. When cavitation occurs, steam bubbles are created at low pressure. As liquid flows from the pump suction to its outlet, the bubbles implode, creating shock waves that attack the pump and cause vibration in the pump, reduced pump performance and mechanical damage which could lead to premature wear or even complete destruction of the pump at different levels

However, the pump inlet temperature is determined and limited by the cold source and the heat exchanges at the condenser. The cavitation margin or subcooling are therefore directly linked to the condensation pressure.

One solution is to regulate the subcooling at the pump inlet as well as the condensing pressure by managing the fluid charge circulating in the installation. In the document EP 2 933 444 A1 , the closed circuit operating according to a Rankine cycle comprises a closed reservoir containing the fluid in the liquid state tapped on the pump line connecting the condenser to the pump. The tank is connected to a pressure regulating device allowing the pressurization of the tank by a regulator regulator injecting a gas such as air or nitrogen and depressurization of the tank by a valve to evacuate part of the gaseous fluid out of the tank. The regulation device therefore uses an external gas and a control unit receiving information from various sensors to control the regulator and the valve.

In this way, at all times, the fluid entering the pump has a sufficient level of sub-cooling with the absence of fluid in the vapor phase, thus limiting the risks of cavitation.

Also the document EP 2 927 438 A1 shows a similar system of producing electrical or mechanical energy.

This type of device still requires improvements to allow its implementation in embedded systems.

There is therefore a need to further simplify electrical or mechanical energy production devices to facilitate their use in various applications.

SUMMARY OF THE INVENTION

• au moins un premier échangeur de chaleur configuré pour être couplé thermiquement à au moins une première source de chaleur, également dénommé évaporateur,
• un expanseur dont une entrée est fluidiquement raccordée à une sortie du premier échangeur,
• un deuxième échangeur de chaleur configuré pour être couplé thermiquement à une deuxième source de chaleur plus froide que la première source de chaleur, également dénommé condenseur,
• au moins une pompe configurée pour mettre en mouvement le fluide de travail dans le circuit fluidique,
• au moins un réservoir, recevant avantageusement le fluide de travail, et agencé entre le deuxième échangeur et la pompe sur une conduite de piquage.

To achieve this objective, one aspect of the present invention relates to a system for producing electrical or mechanical energy as defined by the appended independent claim 1. This system comprises, among other things, a fluid circuit configured to receive a circulating working fluid and comprising a plurality of members intended to be crossed by the working fluid and among which:

• at least one first heat exchanger configured to be thermally coupled to at least one first heat source, also called evaporator,
• an expander whose inlet is fluidly connected to an outlet of the first exchanger,
• a second heat exchanger configured to be thermally coupled to a second heat source colder than the first heat source, also called a condenser,
• at least one pump configured to set in motion the working fluid in the fluid circuit,
• at least one reservoir, advantageously receiving the working fluid, and arranged between the second exchanger and the pump on a tapping pipe.

The fluid circuit of the system being configured so that the working fluid passes successively through at least the pump, the first exchanger, the expander and the second exchanger, then the pump again. The system comprises a device for regulating the fluid charge circulating in the fluid circuit comprising elements for supplying thermal energy to the tank, intended to increase the pressure of the tank and inject working fluid from the tank into the fluidic circuit, and elements for removing energy from the tank, intended to reduce the pressure of the tank and drawing working fluid out of the fluid circuit into the reservoir. The regulating device is configured to operate in a closed circuit with the fluidic circuit and to maintain saturation conditions in the tank so that the tank contains the working fluid simultaneously in the liquid state and in the gaseous state.

The fluid load regulation device allows, through an energy supply into the tank, to expand the working fluid (liquid and vapor phase) present in the tank, which has the consequence of pressurizing the latter and injecting a fraction of the fluid present. in the tank in the fluid circuit. Conversely, a decrease in reservoir energy tends to increase the average density in the reservoir, decrease its pressure and draw a fraction of the circulating fluid into the fluidic circuit.

The system according to the invention makes it possible to avoid having to resort to an external gas source to control the pressure in the tank. Only the working fluid is used, thus limiting the risk of contamination of the working fluid. The compactness of the system is improved by limiting the necessary components, the system does not need a compressor or pressure bottle. The cost of implementation and maintenance is also reduced.

Advantageously, the tank is connected directly, continuously, via the tap pipe to the fluid circuit. According to a possibility not covered by the claims, the reservoir does not include a mechanical element, in particular arranged on the tapping pipe, controlling the injection or suction of the working fluid into the fluid circuit.

The system according to the invention thus has low energy consumption and increased simplicity of operation.

Advantageously, the system according to the invention comprises as thermal energy supply elements at least one heating rod plunging into the tank, or a partial coupling with the first heat source, or an injection module, into the tank, of working fluid taken at the outlet of the first exchanger.

Advantageously, the system according to the invention comprises as energy withdrawal elements a module for ejecting the fluid in the gaseous state, out of the tank, towards the inlet of the second exchanger or an injection module, in the reservoir, of working fluid taken at the outlet of the pump, or a partial coupling with the second heat source.

In addition, the system according to the invention comprises a module for self-regulating the fluid charge circulating in a fluid circuit of an electrical or mechanical energy production system operating according to a Rankine cycle. The self-regulation module is configured to regulate the pressure of a tank connected to the fluid circuit and receiving the working fluid. The self-regulating module, with the details specified in independent claim 1, is mechanically operated, intended to regulate the pressurization and depressurization of the tank. The self-regulation module makes it possible to automatically and preferably only mechanically manage the pressurization and depressurization of the reservoir, that is to say the injection or withdrawal of working fluid into the fluid circuit.

The present invention therefore allows control of subcooling and limits the risks of cavitation by a closed circuit system, that is to say not requiring external fluid and advantageously self-regulated by purely mechanical operation simplifying the system and its functioning.

The system is thus efficient and easily transposable into embedded systems.

• une étape de montée en pression du fluide de travail au travers de la pompe,
• une étape de chauffage du fluide de travail au travers du premier échangeur de chaleur,
• une étape de détente du fluide de travail issu du premier échangeur au travers de l'expanseur,
• une étape de refroidissement du fluide de travail au travers du deuxième échangeur de chaleur,

où il comprend une étape de maintien de conditions saturantes dans le réservoir pour maintenir le fluide de travail simultanément sous deux états gazeux et liquide dans le réservoir par une étape d'apport d'énergie thermique dans le réservoir comprenant l'augmentation de la pression dans le réservoir et l'ajout de fluide de travail dans le circuit fluidique par injection depuis le réservoir, ou alternativement une étape de retrait d'énergie hors du réservoir comprenant la diminution de la pression dans le réservoir et le retrait de fluide de travail du circuit fluidique par aspiration vers le réservoir. Le procédé de l'invention comprend en plus les autres étapes comprises dans la revendication indépendante 15 annexée.Another aspect of the present invention relates to a method of regulating the fluid charge in circulation, defined by the appended independent claim 15, in the fluid circuit of an energy production system according to any one of claims 1 to 14 annexed, including, among others, the following steps:

• a step of increasing the pressure of the working fluid through the pump,
• a step of heating the working fluid through the first heat exchanger,
• a step of expanding the working fluid from the first exchanger through the expander,
• a step of cooling the working fluid through the second heat exchanger,

where it comprises a step of maintaining saturating conditions in the tank to maintain the working fluid simultaneously in two gaseous and liquid states in the tank by a step of supplying thermal energy into the tank comprising increasing the pressure in the reservoir and the addition of working fluid into the fluidic circuit by injection from the reservoir, or alternatively a step of removing energy from the reservoir comprising reducing the pressure in the reservoir and removing working fluid from the circuit fluidic by suction towards the reservoir. The method of the invention further comprises the other steps included in the appended independent claim 15.

In a particularly advantageous manner, the invention makes it possible to make the use of thermal waste at low temperatures profitable, while requiring few energy resources. Furthermore, the present invention provides a simplified, inexpensive system with low energy consumption, while having improved energy efficiency without overloading the pump or increasing the cost and complexity of the system.

BRIEF DESCRIPTION OF THE FIGURES

• La FIGURE 1 illustre un système sur lequel l'invention peut être basée, fonctionnant suivant un cycle de Rankine.
• Les FIGURES 2 à 4 sont des schémas illustrant le réservoir. La FIGURE 2 correspond à une situation à l'équilibre, la FIGURE 3 correspond à l'injection de fluide de travail dans le circuit fluidique,
• La FIGURE 4 correspond à l'aspiration de fluide de travail du circuit fluidique vers le réservoir.
• Les FIGURES 5 à 10 illustrent différents modes de réalisations du dispositif de régulation de la charge fluidique en circulation dans le circuit fluidique. Les FIGURES 5 à 7 correspondent à des modes de réalisation d'éléments d'apport d'énergie thermique dans le réservoir tandis que les FIGURES 8 à 10 correspondent à des modes de réalisation d'éléments de retrait d'énergie du réservoir.
• Les FIGURES 11 et 12 illustrent une partie du système selon un mode de réalisation intégrant un module d'autorégulation. La FIGURE 11 correspond à un premier mode de réalisation, la FIGURE 12 correspond à un deuxième mode de réalisation.
• La FIGURE 13 est une vue en coupe d'un boitier du module d'autorégulation comprenant une soupape et un détendeur.
• La FIGURE 14 représente les différents cas d'autorégulation de la charge fluidique en circulation dans le circuit fluidique.

The aims, objects, as well as the characteristics and advantages of the invention will emerge better from the detailed description of an embodiment of the latter which is illustrated by the following accompanying drawings in which:

• There FIGURE 1 illustrates a system on which the invention can be based, operating according to a Rankine cycle.
• THE FIGURES 2 to 4 are diagrams illustrating the reservoir. There FIGURE 2 corresponds to a situation in equilibrium, the FIGURE 3 corresponds to the injection of working fluid into the fluidic circuit,
• There FIGURE 4 corresponds to the suction of working fluid from the fluid circuit towards the reservoir.
• THE FIGURES 5 to 10 illustrate different embodiments of the device for regulating the fluid charge circulating in the fluid circuit. THE FIGURES 5 to 7 correspond to embodiments of elements for providing thermal energy in the tank while the FIGURES 8 to 10 correspond to embodiments of elements for removing energy from the reservoir.
• THE FIGURES 11 and 12 illustrate part of the system according to an embodiment integrating a self-regulation module. There FIGURE 11 corresponds to a first embodiment, the FIGURE 12 corresponds to a second embodiment.
• There FIGURE 13 is a sectional view of a housing of the self-regulation module comprising a valve and a regulator.
• There FIGURE 14 represents the different cases of self-regulation of the fluid charge circulating in the fluid circuit.

THE figures 1 to 13 show isolated portions which contribute to the invention only within the set of features defined by the appended independent claim 1.

There figures 14 shows steps of a process which contributes to the invention only in the set of steps defined by the appended independent claim 15.

The drawings are given by way of example and are not necessarily limiting to the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily on the scale of practical applications. The invention is not defined than by the appended independent claims 1, 15 and their dependent claims.

DETAILED DESCRIPTION OF THE INVENTION

• ∘ Suivant un mode de réalisation non couvert par les revendications, le réservoir 105 est directement raccordé fluidiquement à la conduite de piquage 114 qui est elle-même directement fluidiquement raccordée au circuit fluidique entre le deuxième échangeur 102 et la pompe 104.
• ∘ Suivant un mode de réalisation non couvert par les revendications, le système ne comprend pas d'élément de régulation entre le réservoir 105 et le circuit fluidique.
• ∘ Suivant un mode de réalisation, le fluide de travail est un fluide organique.
• ∘ Suivant un mode de réalisation, le fluide de travail est un fluide inorganique.
• ∘ Suivant un mode de réalisation, le dispositif de régulation ne comprend pas de fluide autre que le fluide de travail. Le dispositif de régulation ne fait appel qu'au fluide de travail présent dans le circuit fluidique et dans le réservoir 105.
• ∘ Suivant un mode de réalisation, les éléments d'apport d'énergie thermique comprennent au moins une canne chauffante 5 plongeant dans le réservoir 105.
  La présence de canne de chauffage 5 est une solution qui, malgré une forte consommation d'énergie, permet une bonne régulation et un faible coût d'installation.
• ∘ Suivant un mode de réalisation, les éléments d'apport d'énergie thermique comprennent un module d'injection, dans le réservoir 105, de fluide de travail prélevé à la sortie 11 du premier échangeur 101.
  Le fluide de travail prélevé à la sortie 11 du premier échangeur 101, qui est avantageusement un évaporateur, est à haute température et haute pression. Son injection dans le réservoir 105 augmente la pression du réservoir Pr et pousse le fluide de travail stocké dans le réservoir 105 vers le circuit fluidique. Cette solution a l'avantage d'une grande simplicité sans risque de contamination par un autre fluide et une faible consommation énergétique.
• ∘ Suivant un mode de réalisation, les éléments d'apport d'énergie thermique comprennent un couplage, au moins partiel, du réservoir 105 avec la première source de chaleur 1.
  La première source de chaleur 1 permet de réchauffer le fluide de travail contenu dans le réservoir 105 augmentant ainsi la pression du réservoir Pr et pousse le fluide de travail stocké dans le réservoir 105 vers le circuit fluidique.
• ∘ Suivant un mode de réalisation, les éléments de retrait d'énergie comprennent un module d'éjection, hors du réservoir 105, du fluide de travail à l'état gazeux 4 en direction de l'entrée 21 du deuxième échangeur 102.
  Le fluide de travail à l'état gazeux 4 est éjecté dans le circuit fluidique au niveau de l'entrée 21 du deuxième échangeur 102, qui est avantageusement un condenseur. L'évacuation du fluide à l'état gazeux 4 du réservoir 105 diminue la pression du réservoir Pr et aspire le fluide de travail du circuit fluidique vers le réservoir 105.
  Avantageusement, le deuxième échangeur 102 est agencé à une hauteur supérieure du réservoir 105 de sorte que le déplacement de fluide gazeux ne se fasse qu'en direction du deuxième échangeur 102 par différence de pression hydrostatique. Cette solution présente un fort potentiel de refroidissement.
• ∘ Suivant un mode de réalisation, les éléments de retrait d'énergie comprennent un module d'injection, dans le réservoir 105, de fluide de travail prélevé à la sortie 42 de la pompe 104.
  Le fluide de travail prélevé à la sortie 42 de la pompe 104, c'est-à-dire après la sortie 22 du deuxième échangeur 102, qui est avantageusement un condenseur, est à basse température et basse pression. Son injection dans le réservoir 105 diminue la pression du réservoir et aspire le fluide de travail du circuit fluidique vers le réservoir 105.
• ∘ Suivant un mode de réalisation, les éléments de retrait d'énergie comprennent un couplage au moins partiel du réservoir 105 avec la deuxième source de chaleur 2.
  La deuxième source de chaleur 2 permet de refroidir le fluide de travail contenu dans le réservoir 105 diminuant ainsi la pression du réservoir Pr et aspirant le fluide de travail du circuit fluidique vers le réservoir 105.
• ∘ Suivant un mode de réalisation, les éléments d'apport d'énergie thermique comprennent un module d'injection, dans le réservoir 105, de fluide de travail prélevé à la sortie 12 du premier échangeur 101 et les éléments de retrait d'énergie comprennent un module d'éjection du fluide à l'état gazeux 4, hors du réservoir 105, en direction de l'entrée du deuxième échangeur 21 ou un module d'injection, dans le réservoir 105, de fluide de travail prélevé à la sortie de la pompe 104.
• ∘ Le système comprend un module d'autorégulation 200 à fonctionnement mécanique destiné à réguler la pressurisation et la dépressurisation du réservoir 105.
  Le système régule automatiquement la pression dans le réservoir 105 de sorte à réguler la charge fluidique du circuit. Ces régulations se font de manière mécanique, c'est-à-dire que le module d'autorégulation 200 ne comprend que des éléments mécaniques.
• ∘ Suivant un mode de réalisation, le module d'autorégulation 200 comprend un détendeur 201 compensé couplé à une soupape 203 compensée.
• ∘ Le module d'autorégulation 200 comprend un boitier 205 recevant un détendeur 201 associé à un ressort de détendeur 202 et une soupape 203 associée à un ressort de soupape 204.
  Ce module d'autorégulation 200 est un élément avantageusement unitaire, monobloc, avec une compacité permettant son intégration dans de nombreuses installations et notamment dans les systèmes embarqués.
• ∘ Suivant un mode de réalisation, le boitier 205 comprend une première ouverture 206 en liaison fluidique avec le réservoir 105 de sorte à être soumise à la pression du réservoir Pr.
  La première ouverture 206 est en communication fluidique avec le réservoir 105, raccordée directement c'est-à-dire sans élément autre qu'une conduite.
• ∘ Suivant un mode de réalisation, le boitier 205 comprend une deuxième ouverture 207 en liaison fluidique avec un module de production de pression de contrôle de sorte à être soumise à une pression contrôlée Pc.
  La deuxième ouverture 207 est en communication fluidique avec un module gérant une pression contrôlée, avantageusement raccordée directement c'est-à-dire sans élément autre qu'une conduite.
• ∘ Suivant un mode de réalisation, le boitier 205 comprend une troisième ouverture 208 d'injection de fluide de travail, dans le réservoir 105, en provenance de la sortie 12 du premier échangeur 101.
  La troisième ouverture 208 est en communication fluidique avec la sortie 12 du premier échangeur 101, avantageusement raccordée directement c'est-à-dire sans élément autre qu'une conduite.
• ∘ Suivant un mode de réalisation, le boitier 205 comprend une quatrième ouverture 209 d'injection, dans le réservoir 105, de fluide de travail en provenance de la sortie 42 de la pompe 104 ou d'éjection de fluide de travail à l'état gazeux 4, hors du réservoir 105, vers l'entrée 21 du deuxième échangeur 102.
  La quatrième ouverture 208 est en communication fluidique avec la sortie 42 de la pompe 104 ou l'entrée 21 du deuxième échangeur 102, avantageusement directe c'est-à-dire sans élément autre qu'une conduite.
• ∘ Suivant un mode de réalisation, la pression de contrôle Pc est égale à la pression de saturation du fluide en entrée 41 de pompe 104,
  avantageusement pendant l'opération, le fonctionnement, du système.
• ∘ Suivant un mode de réalisation, le ressort de soupape 204 présente une raideur Ks supérieure à celle Kd du ressort de détendeur 202.
• ∘ Suivant un mode de réalisation, le module d'autorégulation 200 est configuré pour être à l'équilibre, avec le détendeur 201 fermé et la soupape 203 fermée, lorsque la pression du réservoir Pr est à la fois supérieure à la somme de la pression de contrôle Pc et de la raideur Kd du ressort du détendeur 202 et inférieure à la somme de la pression de contrôle Pc et de la raideur Ks du ressort de la soupape 204. De cette manière, la cavitation en entrée de pompe est quasi nulle et le sous-refroidissement non excessif.
• ∘ Suivant un mode de réalisation, le module d'autorégulation 200 est configuré pour que l'ouverture de la soupape 203 mette en connexion fluidique le réservoir 105 et l'entrée 21 du deuxième échangeur 102 ou la sortie 42 de la pompe 104 par la quatrième ouverture 209.
• ∘ Suivant un mode de réalisation, le module d'autorégulation 200 est configuré pour que l'ouverture du détendeur 201 mette en connexion fluidique le réservoir 105 et la sortie 12 du premier échangeur 101 par la troisième ouverture 208.
• ∘ Suivant un mode de réalisation, le module de production de pression de contrôle comprend un ballon 210 rempli de fluide de travail connecté fluidiquement à la deuxième ouverture 207 du boitier 205, le ballon 210 étant agencé pour plonger dans le fluide de travail du circuit fluidique en sortie 22 du deuxième échangeur 102 de sorte que la température du fluide contenu dans le ballon 210 soit identique à celle du fluide de travail du circuit fluidique en entrée 41 de pompe 104. De cette manière, la pression du fluide contenu dans le ballon 210, à saturation, est identique à la pression de saturation du fluide de travail du circuit fluidique en entrée 41 de pompe 104.
• ∘ Suivant un mode de réalisation, le module de production de pression de contrôle comprend une source de gaz à pression régulée en connexion fluidique avec la deuxième ouverture 207 du boitier 205, des capteurs de pression et/ou de température entrée 41 de pompe 104 et des moyens de régulations de la pression de la source de gaz de sorte à définir une pression de contrôle Pc.
• ∘ Suivant un mode de réalisation, le procédé est tel qu'il comprend lorsque la pression du réservoir Pr est supérieure à la somme de la pression de contrôle Pc et de la raideur Ks du ressort de la soupape 204, l'ouverture de la soupape 203 mettant en connexion fluidique le réservoir 105 et l' entrée 21 du deuxième échangeur 102 ou la sortie 42 de la pompe 104 par la quatrième ouverture 209 de sorte à diminuer la pression du réservoir Pr et retirer par aspiration vers le réservoir 105, du fluide de travail du circuit fluidique.
• ∘ Suivant un mode de réalisation, le procédé est tel qu'il comprend lorsque la pression du réservoir Pr est inférieure à la pression de contrôle Pc additionnée à la raideur Kd du ressort du détendeur 202, l'ouverture du détendeur mettant en connexion fluidique le réservoir 105 et la sortie 12 du premier échangeur 101 par la troisième ouverture 208 de sorte à augmenter la pression du réservoir Pr, et ajouter par injection depuis le réservoir 105 du fluide de travail dans le circuit fluidique.
• ∘ La sortie 42 de pompe 104 est directement raccordée à l'entrée 11 du premier échangeur 101.
• ∘ La sortie 12 du premier échangeur 101 est directement raccordée à l'entrée 31 de l'expanseur 103.
• ∘ La sortie 32 de l'expanseur 103 est directement raccordée à entrée 21 du deuxième échangeur 102.
• ∘ La sortie 22 du deuxième échangeur 102 est directement raccordée à la pompe 104.
• ∘ Le réservoir 105 est directement raccordé au circuit fluidique entre la sortie 22 du deuxième échangeur 102 et l'entrée 41 de pompe 104.
• ∘ Le circuit fluidique est hermétique, préférentiellement le système est hermétique. Ceci permet avantageusement de limiter les risques pour l'environnement et pour l'homme lorsqu'ils sont toxiques.

Before beginning a detailed review of embodiments of the invention, optional characteristics are set out below which may possibly be used in association or alternatively, where each embodiment according to the invention comprises at least all of the characteristics of 'one of the independent claims annexed:

• ∘ According to an embodiment not covered by the claims, the reservoir 105 is directly fluidly connected to the tapping pipe 114 which is itself directly fluidically connected to the fluidic circuit between the second exchanger 102 and the pump 104.
• ∘ According to an embodiment not covered by the claims, the system does not include a regulating element between the reservoir 105 and the fluid circuit.
• ∘ According to one embodiment, the working fluid is an organic fluid.
• ∘ According to one embodiment, the working fluid is an inorganic fluid.
• ∘ According to one embodiment, the regulation device does not include any fluid other than the working fluid. The regulation device only uses the working fluid present in the fluid circuit and in the reservoir 105.
• ∘ According to one embodiment, the thermal energy supply elements comprise at least one heating rod 5 plunging into the tank 105.
  The presence of heating rod 5 is a solution which, despite high energy consumption, allows good regulation and a low installation cost.
• ∘ According to one embodiment, the thermal energy supply elements comprise an injection module, into the reservoir 105, of working fluid taken at the outlet 11 of the first exchanger 101.
  The working fluid taken at the outlet 11 of the first exchanger 101, which is advantageously an evaporator, is at high temperature and high pressure. Its injection into the reservoir 105 increases the pressure of the reservoir Pr and pushes the working fluid stored in the reservoir 105 towards the fluidic circuit. This solution has the advantage of great simplicity without risk of contamination by another fluid and low energy consumption.
• ∘ According to one embodiment, the thermal energy supply elements comprise at least partial coupling of the reservoir 105 with the first heat source 1.
  The first heat source 1 makes it possible to heat the working fluid contained in the tank 105, thus increasing the pressure of the tank Pr and pushes the working fluid stored in the tank 105 towards the fluid circuit.
• ∘ According to one embodiment, the energy removal elements comprise an ejection module, out of the tank 105, of the working fluid in the gaseous state 4 towards the inlet 21 of the second exchanger 102.
  The working fluid in the gaseous state 4 is ejected into the fluid circuit at the inlet 21 of the second exchanger 102, which is advantageously a condenser. The evacuation of the fluid in the gaseous state 4 from the tank 105 reduces the pressure of the tank Pr and draws the working fluid from the fluidic circuit towards the tank 105.
  Advantageously, the second exchanger 102 is arranged at a greater height of the tank 105 so that the movement of gaseous fluid only occurs in the direction of the second exchanger 102 by hydrostatic pressure difference. This solution has a high cooling potential.
• ∘ According to one embodiment, the energy removal elements comprise an injection module, into the reservoir 105, of working fluid taken at the outlet 42 of the pump 104.
  The working fluid taken at the outlet 42 of the pump 104, that is to say after the outlet 22 of the second exchanger 102, which is advantageously a condenser, is at low temperature and low pressure. Its injection into the reservoir 105 reduces the pressure of the reservoir and draws the working fluid from the fluidic circuit towards the reservoir 105.
• ∘ According to one embodiment, the energy removal elements comprise at least partial coupling of the reservoir 105 with the second heat source 2.
  The second heat source 2 makes it possible to cool the working fluid contained in the tank 105, thus reducing the pressure of the tank. Pr and suck the working fluid from the fluidic circuit towards the reservoir 105.
• ∘ According to one embodiment, the thermal energy supply elements comprise an injection module, into the reservoir 105, of working fluid taken at the outlet 12 of the first exchanger 101 and the energy withdrawal elements comprise a module for ejecting the fluid in the gaseous state 4, out of the tank 105, towards the inlet of the second exchanger 21 or an injection module, into the tank 105, of working fluid taken at the outlet of the pump 104.
• ∘ The system includes a self-regulation module 200 with mechanical operation intended to regulate the pressurization and depressurization of the tank 105.
  The system automatically regulates the pressure in the tank 105 so as to regulate the fluid load of the circuit. These regulations are carried out mechanically, that is to say that the self-regulation module 200 only includes mechanical elements.
• ∘ According to one embodiment, the self-regulation module 200 comprises a compensated regulator 201 coupled to a compensated valve 203.
• ∘ The self-regulation module 200 comprises a housing 205 receiving a regulator 201 associated with a regulator spring 202 and a valve 203 associated with a valve spring 204.
  This self-regulation module 200 is an advantageously unitary, monobloc element, with a compactness allowing its integration into numerous installations and in particular in on-board systems.
• ∘ According to one embodiment, the housing 205 comprises a first opening 206 in fluid connection with the reservoir 105 so as to be subjected to the pressure of the reservoir Pr.
  The first opening 206 is in fluid communication with the reservoir 105, connected directly, that is to say without any element other than a pipe.
• ∘ According to one embodiment, the housing 205 comprises a second opening 207 in fluid connection with a control pressure production module so as to be subjected to a controlled pressure Pc.
  The second opening 207 is in fluid communication with a module managing a controlled pressure, advantageously connected directly, that is to say without any element other than a pipe.
• ∘ According to one embodiment, the housing 205 comprises a third opening 208 for injecting working fluid, into the reservoir 105, coming from the outlet 12 of the first exchanger 101.
  The third opening 208 is in fluid communication with the outlet 12 of the first exchanger 101, advantageously connected directly, that is to say without any element other than a pipe.
• ∘ According to one embodiment, the housing 205 comprises a fourth opening 209 for injecting, into the reservoir 105, working fluid coming from the outlet 42 of the pump 104 or for ejecting working fluid in the state gas 4, outside the tank 105, towards the inlet 21 of the second exchanger 102.
  The fourth opening 208 is in fluid communication with the outlet 42 of the pump 104 or the inlet 21 of the second exchanger 102, advantageously direct, that is to say without any element other than a pipe.
• ∘ According to one embodiment, the control pressure Pc is equal to the saturation pressure of the fluid at the inlet 41 of pump 104,
  advantageously during the operation, operation, of the system.
• ∘ According to one embodiment, the valve spring 204 has a stiffness Ks greater than that Kd of the regulator spring 202.
• ∘ According to one embodiment, the self-regulation module 200 is configured to be in equilibrium, with the regulator 201 closed and the valve 203 closed, when the pressure of the reservoir Pr is both greater than the sum of the pressure control Pc and the stiffness Kd of the spring of the regulator 202 and less than the sum of the pressure of control Pc and the stiffness Ks of the valve spring 204. In this way, the cavitation at the pump inlet is almost zero and the subcooling is not excessive.
• ∘ According to one embodiment, the self-regulation module 200 is configured so that the opening of the valve 203 places the reservoir 105 in fluid connection and the inlet 21 of the second exchanger 102 or the outlet 42 of the pump 104 via the fourth opening 209.
• ∘ According to one embodiment, the self-regulation module 200 is configured so that the opening of the regulator 201 places the tank 105 in fluid connection and the outlet 12 of the first exchanger 101 via the third opening 208.
• ∘ According to one embodiment, the control pressure production module comprises a balloon 210 filled with working fluid fluidly connected to the second opening 207 of the housing 205, the balloon 210 being arranged to immerse in the working fluid of the fluidic circuit at outlet 22 of the second exchanger 102 so that the temperature of the fluid contained in the tank 210 is identical to that of the working fluid of the fluid circuit at the inlet 41 of pump 104. In this way, the pressure of the fluid contained in the tank 210 , at saturation, is identical to the saturation pressure of the working fluid of the fluid circuit at the inlet 41 of pump 104.
• ∘ According to one embodiment, the control pressure production module comprises a gas source at regulated pressure in fluid connection with the second opening 207 of the housing 205, pressure and/or temperature sensors inlet 41 of pump 104 and means for regulating the pressure of the gas source so as to define a control pressure Pc.
• ∘ According to one embodiment, the method is such that it comprises when the pressure of the reservoir Pr is greater than the sum of the control pressure Pc and the stiffness Ks of the spring of the valve 204, the opening of the valve 203 placing the reservoir 105 in fluid connection with the inlet 21 of the second exchanger 102 or the outlet 42 of the pump 104 via the fourth opening 209 so as to reduce the pressure of the reservoir Pr and withdraw fluid by suction towards the reservoir 105 working of the fluidic circuit.
• ∘ According to one embodiment, the method is such that it comprises when the pressure of the reservoir Pr is less than the control pressure Pc added to the stiffness Kd of the spring of the regulator 202, the opening of the regulator putting into fluidic connection the tank 105 and the outlet 12 of the first exchanger 101 through the third opening 208 so as to increase the pressure of the tank Pr, and add by injection from the tank 105 the working fluid into the fluidic circuit.
• ∘ The outlet 42 of pump 104 is directly connected to the inlet 11 of the first exchanger 101.
• ∘ Output 12 of the first exchanger 101 is directly connected to inlet 31 of expander 103.
• ∘ Outlet 32 of expander 103 is directly connected to inlet 21 of second exchanger 102.
• ∘ Outlet 22 of the second exchanger 102 is directly connected to pump 104.
• ∘ Reservoir 105 is directly connected to the fluid circuit between outlet 22 of the second exchanger 102 and inlet 41 of pump 104.
• ∘ The fluid circuit is hermetic, preferably the system is hermetic. This advantageously makes it possible to limit the risks for the environment and for humans when they are toxic.

The invention also makes it possible to minimize the necessary load by confining the working fluid. However, the working fluid can represent up to more than 20% of the total cost of a Rankine machine. The invention thus minimizes the capital and operating costs of such a system.

An advantage of the invention is to be able to control the charge of the fluid and therefore the sub-cooling, so that it is neither too small (risk of cavitation) nor too large (degradation of the overall performance of the cycle).

• Selon un mode de réalisation avantageux, mais non limitatif, le fluide de travail est un fluide organique. Ce type de fluide permet d'atteindre un régime supercritique, régime pour autant non limitatif de l'invention, même à des températures relativement basses en sortie d'échangeur chaud. On entend par fluide organique, un fluide composé de molécules ou d'un mélange de molécules constituées d'atomes de carbone, d'hydrogène et éventuellement d'autres atomes tels que par exemple l'oxygène, le fluor, l'azote, le chlore, le brome.
• Dans un autre mode de réalisation, le fluide de travail n'est pas un fluide organique.
• Selon un mode de réalisation, le premier échangeur est configuré pour amener à sa sortie le fluide de travail à une température inférieure à 200°C et de préférence inférieure à 150°C.
• Selon un mode de réalisation, le circuit est configuré de manière à ce que la température du fluide de travail en sortie 12 du premier échangeur 101 soit comprise entre la température ambiante et 200°C et de préférence entre la température ambiante et 150°C.
• Selon un mode de réalisation, le système comprend la source chaude 1. La source chaude 1 et le premier échangeur 101 sont configurés pour fournir à la sortie du premier échangeur une température pour le fluide de travail inférieure à 200°C et de préférence inférieure à 150°C. Selon un mode de réalisation, le fluide de travail est frigorigène et choisi parmi le R410a, le R134a, le R227ea, ou le R245fa. Ces fluides permettent d'atteindre un régime supercritique avec des sources chaudes aux températures inférieures à 200°C.lls sont donc particulièrement avantageux pour produire de l'énergie à partir de rejets thermiques d'usines ou de moteurs thermiques.
• Selon un mode de réalisation, le deuxième échangeur 102 est configuré pour amener à sa sortie 22 le fluide de travail à une température comprise entre la température ambiante et 150°C, la température du fluide de travail en sortie 22 du deuxième échangeur 102 étant inférieure à la température du fluide de travail en sortie 12 du premier échangeur 101.
• Selon un mode de réalisation, le système comprend la première source de chaleur 1, la première source de chaleur 1 étant couplée thermiquement avec un circuit de rejet thermique d'une usine ou d'un moteur.
• Selon un mode de réalisation, le premier échangeur 101 de chaleur est configuré de sorte à chauffer le fluide de travail ; l'expanseur 103 est configuré de sorte à diminuer la pression du fluide de travail et le deuxième échangeur 102 de chaleur est configuré de sorte à refroidir le fluide de travail. La pompe 104 est configurée de sorte à augmenter la pression du fluide de travail.
• Selon un mode de réalisation, le système comprend un dispositif de conversion d'énergie configuré pour convertir un mouvement mécanique produit par l'expanseur 103 en une énergie électrique ou mécanique et configuré de manière à ce que la puissance fournie par le dispositif de conversion d'énergie soit inférieure à 100 kW.
• Selon un mode de réalisation, l'expanseur 103 est une turbine, de préférence cinétique.
• Selon un mode de réalisation, l'expanseur 103 est une machine volumétrique.
• Selon un mode de réalisation, l'expanseur 103 est une machine volumétrique, du type suivant : un compresseur volumétrique fonctionnant en expanseur.
• Selon un mode de réalisation, l'expanseur 103 est une machine hermétique ; ladite machine comprenant l'expanseur, un arbre et l'alternateur; l'expanseur étant raccordé à l'arbre et l'arbre étant raccordé à l'alternateur.

The invention thus offers an effective solution for recovering thermal discharges presenting relatively low temperatures.

• According to an advantageous, but non-limiting, embodiment, the working fluid is an organic fluid. This type of fluid makes it possible to reach a supercritical regime, a regime which does not limit the invention, even at relatively low temperatures at the outlet of the hot exchanger. By organic fluid is meant a fluid composed of molecules or a mixture of molecules consisting of carbon atoms, hydrogen and possibly other atoms such as for example oxygen, fluorine, nitrogen, chlorine, bromine.
• In another embodiment, the working fluid is not an organic fluid.
• According to one embodiment, the first exchanger is configured to bring the working fluid to its outlet at a temperature lower than 200°C and preferably lower than 150°C.
• According to one embodiment, the circuit is configured so that the temperature of the working fluid at the outlet 12 of the first exchanger 101 is between ambient temperature and 200°C and preferably between ambient temperature and 150°C.
• According to one embodiment, the system comprises the hot source 1. The hot source 1 and the first exchanger 101 are configured to provide at the outlet of the first exchanger a temperature for the working fluid lower than 200°C and preferably lower than 150°C. According to one embodiment, the working fluid is refrigerant and chosen from R410a, R134a, R227ea, or R245fa. These fluids make it possible to reach a supercritical regime with hot sources at temperatures below 200°C. They are therefore particularly advantageous for producing energy from thermal waste from factories or thermal engines.
• According to one embodiment, the second exchanger 102 is configured to bring the working fluid to its outlet 22 at a temperature between ambient temperature and 150°C, the temperature of the working fluid at the outlet 22 of the second exchanger 102 being lower at the temperature of the working fluid at outlet 12 of the first exchanger 101.
• According to one embodiment, the system comprises the first heat source 1, the first heat source 1 being thermally coupled with a thermal rejection circuit of a factory or an engine.
• According to one embodiment, the first heat exchanger 101 is configured so as to heat the working fluid; the expander 103 is configured so as to reduce the pressure of the working fluid and the second heat exchanger 102 is configured so as to cool the working fluid. Pump 104 is configured to increase the pressure of the working fluid.
• According to one embodiment, the system comprises an energy conversion device configured to convert a mechanical movement produced by the expander 103 into electrical or mechanical energy and configured so that the power supplied by the conversion device d energy is less than 100 kW.
• According to one embodiment, the expander 103 is a turbine, preferably kinetic.
• According to one embodiment, the expander 103 is a volumetric machine.
• According to one embodiment, the expander 103 is a volumetric machine, of the following type: a volumetric compressor operating as an expander.
• According to one embodiment, the expander 103 is a hermetic machine; said machine comprising the expander, a shaft and the alternator; the expander being connected to the shaft and the shaft being connected to the alternator.

For the remainder of the description, the term 'top' and `bottom', or their derivatives, means a quality of relative positioning of an element of the system according to the invention when it is installed functionally, the 'top ' being oriented away from the ground and the `bottom being oriented towards the ground. The upper end is at the top and the lower end is at the bottom.

The upstream and downstream at a given point are taken with reference to the direction of circulation of the fluid in the circuit.

In the present description, the expression “A fluidically connected to B” does not necessarily mean that there is no organ between A and B.

• Un fluide de travail. Ce fluide de travail est avantageusement frigorigène. Le fluide de travail est de préférence organique ce qui permet éventuellement d'atteindre un régime supercritique (également désigné supercritique) tout en conservant des niveaux de pression et de température relativement limités. Le fluide de travail est de préférence choisi parmi le R410a, le R134a, le R227a, le R245fa. On entend par fluide supercritique, un fluide ayant atteint un régime supercritique.
• Un premier échangeur. 101 Ce premier échangeur 101 est thermiquement couplé à une première source de chaleur 1, dénommée source chaude, par exemple chauffée par les rejets thermiques. De préférence, il permet au fluide d'atteindre un régime supercritique. Le premier échangeur peut ainsi être qualifié d'évaporateur en cas de fonctionnement en régime sous-critique. Le fluide de travail entre par l'entrée 11 dans le premier échangeur 101 à l'état liquide comprimé et ressort à la sortie 12 du premier échangeur 101 à l'état de vapeur comprimée. La température critique du fluide de travail est, par exemple de l'ordre de 70°C, pour un fluide de travail de type gaz réfrigérant R410a. Le R410a est l'un des fluides frigorigènes les plus fréquemment utilisés pour faire fonctionner une pompe à chaleur. Le R410a présente l'avantage de ne pas être nocif pour la couche d'ozone, tout en présentant un bon rendement énergétique. Il a notamment une capacité de compression et une puissance frigorifique plus élevées que beaucoup d'autres fluides frigorigènes. Il augmente donc non seulement les possibilités de chauffage (même à basse température), mais également de refroidissement. La température critique est, par exemple, de l'ordre de : 101 °C pour le fluide R134a, 103°C pour le fluide R227a et 154°C pour le fluide R245fa.
• Un expanseur 103 tel que par exemple un compresseur volumétrique. Cet expanseur 103 permet de détendre le fluide et de produire une énergie mécanique à partir de cette détente. Le fluide entre par une entrée 31 de l'expanseur 103 sous forme de vapeur comprimée haute pression et ressort à la sortie 32 de l'expanseur 103 sous forme de vapeur détendue basse pression. Dans un mode de réalisation, cette énergie est récupérée sur un arbre tournant. Cette énergie mécanique peut ensuite être récupérée sous forme électrique au niveau d'un l'alternateur situé sur ledit arbre tournant. L'expanseur 103 est avantageusement dérivé d'un compresseur volumétrique conventionnel de l'industrie frigorifique.
• un deuxième échangeur de chaleur 102 thermiquement couplé à une deuxième source de chaleur 2, plus froide que la première source de chaleur 1 et permettant de refroidir le fluide de travail. Lors de ce refroidissement, la température de saturation est atteinte. Le refroidissement s'accompagne dès lors du phénomène de condensation. Le fluide pénètre dans le deuxième échangeur 102 par l'entrée 21 à l'état de vapeur détendue basse pression et ressort à la sortie 22 à l'état liquide.
• une pompe. De préférence, elle permet au fluide de travail d'être comprimé. Le fluide de travail pénètre au niveau de l'entrée 41 de pompe 104 à l'état liquide et ressort à la sortie 42 à l'état liquide comprimée haute pression.

There figure 1 illustrates an example of a system on which the present invention, defined by the appended independent claim 1, may be based. This system is particularly advantageous for small power electrical production (for example from a few kilowatts to a hundred kilowatts). It is configured to implement a Rankine thermodynamic cycle. It includes commonly used components:

• A working fluid. This working fluid is advantageously refrigerant. The working fluid is preferably organic, which possibly makes it possible to reach a supercritical regime (also called supercritical) while maintaining relatively limited pressure and temperature levels. The working fluid is preferably chosen from R410a, R134a, R227a, R245fa. By supercritical fluid we mean a fluid that has reached a supercritical regime.
• A first interchange. 101 This first exchanger 101 is thermally coupled to a first heat source 1, called a hot source, for example heated by thermal discharges. Preferably, it allows the fluid to reach a supercritical regime. The first exchanger can thus be qualified as an evaporator when operating in subcritical mode. The working fluid enters through inlet 11 into the first exchanger 101 in the compressed liquid state and exits at the outlet 12 of the first exchanger 101 in the compressed vapor state. The critical temperature of the working fluid is, for example of the order of 70°C, for a working fluid of the R410a refrigerant gas type. R410a is one of the most frequently used refrigerants to operate a heat pump. R410a has the advantage of not being harmful to the ozone layer, while being very energy efficient. In particular, it has a higher compression capacity and refrigerating power than many other refrigerants. It therefore not only increases the possibilities of heating (even at low temperatures), but also of cooling. The critical temperature is, for example, of the order of: 101°C for the R134a fluid, 103°C for the R227a fluid and 154°C for the R245fa fluid.
• An expander 103 such as for example a positive displacement compressor. This expander 103 makes it possible to relax the fluid and produce mechanical energy from this relaxation. The fluid enters through an inlet 31 of the expander 103 in the form of high pressure compressed vapor and exits at the outlet 32 of the expander 103 in the form of low pressure expanded vapor. In one embodiment, this energy is recovered on a rotating shaft. This mechanical energy can then be recovered in electrical form at the level of an alternator located on said rotating shaft. The expander 103 is advantageously derived from a conventional positive displacement compressor in the refrigeration industry.
• a second heat exchanger 102 thermally coupled to a second heat source 2, colder than the first heat source 1 and making it possible to cool the working fluid. During this cooling, the saturation temperature is reached. Cooling is therefore accompanied by the phenomenon of condensation. The fluid enters the second exchanger 102 via inlet 21 in the state of low pressure expanded vapor and exits at outlet 22 in the liquid state.
• a pump. Preferably, it allows the working fluid to be compressed. The working fluid enters at the inlet 41 of pump 104 in the liquid state and exits at the outlet 42 in the high pressure compressed liquid state.

The outlet 42 of the pump 104 is in fluid communication with the inlet 11 of the first exchanger 101, advantageously through a pipe of the first exchanger 110. The outlet 12 of the first exchanger 101 is in fluid communication with the inlet 31 of the expander 103, advantageously by an expander pipe 111. The outlet 32 of the expander 103 is in fluid communication with the inlet 21 of the second exchanger 102, advantageously by a second exchanger pipe 112. The outlet 22 of the second exchanger 102 is in fluid communication with the inlet 41 of pump 104, advantageously by a pump pipe 113.

The fluidic circuit is a closed circuit.

Typically, the system according to the invention comprises a reservoir 105 configured to receive and store the working fluid. The reservoir 105 is arranged between the second exchanger 102 and the pump 104, more precisely between the outlet 22 of the second exchanger 102 and the inlet 41 of pump 104. The reservoir 105 is connected to the fluidic circuit by a tapping pipe 114. tank 105 is said to be offline.

The reservoir 105 is connected directly via the tapping pipe 114 to the fluid circuit. The reservoir 105 is said to be continuously connected to the fluid circuit. The tapping pipe 114 does not include a pump or valve type member.

The reservoir 105 receives the working fluid simultaneously in two states, liquid 3 and gaseous 4. The reservoir is subjected to conditions of saturation of the working fluid allowing the fluid to be simultaneously in the liquid state 3 and in the state gaseous 4 in the tank 105. The fluid in the liquid state 3 is located in the lower part of the tank 105 while the fluid in the gaseous state 4 is located in the upper part of the tank 105.

The arrangement of the reservoir 105 is configured so that the pressure of the reservoir Pr is uniform with the pressure at the inlet 41 of pump 104. As a result, the reservoir 105 and in particular the tapping pipe 114 is arranged in immediate and sufficient proximity to the the inlet of the pump 104. The tapping pipe 114 is preferably of reduced length and horizontal. We mean immediate proximity for example: at least one meter, preferably less than 0.5 meters, or even less than 0.2 meters; this proximity of the reservoir 105 and the inlet 41 of pump 104 also allows rapid restoration of the pressure at the inlet 41 of pump 104 to limit the risks of cavitation.

According to the invention, the system comprises a device for regulating the fluid charge circulating in the fluid circuit. This regulation device is configured to operate in a closed circuit with the fluidic circuit. In addition, a self-regulation device only uses the working fluid present in the fluid circuit and in the reservoir 105. The regulation device is configured to maintain saturation conditions in the reservoir 105.

The regulation device is configured so that at the inlet 41 of pump 104 the temperature of the working fluid is equal to the saturation temperature of the fluid minus the subcooling temperature difference. Likewise, the pressure at the inlet 41 of pump 104 is uniform with the pressure of the reservoir 105.

The regulation device comprises elements for providing thermal energy in the tank 105 intended to increase the pressure of the tank and inject the working fluid from the tank 105 towards the fluidic circuit. The energy supply elements increase the enthalpy of the tank, the temperature of the fluid in the tank 105 as well as the pressure increases while the density decreases which induces the movement of the working fluid from the tank 105 towards the fluidic circuit and more precisely the pump pipe 113. The movement takes place passively, that is to say without the action of a mechanical member at the level of the tapping pipe 114. The working fluid injected into the fluidic circuit is at the liquid state.

The energy supply elements can be diverse as illustrated in figures 5 to 7 .

According to a first embodiment illustrated in Figure 5 , they include one or two or more heating rods 5 immersed in the tank 105. The heating rods 5 heat the working fluid thus increasing its temperature.

According to a second embodiment illustrated in Figure 6 , they include a working fluid injection module, in the tank 105, taken from the outlet 12 of the first exchanger 101. The injection module comprises a working fluid injection pipe 116 fluidly connected to a first end at exit 12 of the first interchange 101 and at a second end to the tank 105. The working fluid taken and injected into the tank 105 is in the state of high pressure compressed steam. Preferably, the module comprises an injector 6 and/or a valve, or any other injection control means, intended to control the injection of working fluid.

According to a third embodiment illustrated in Figure 7 , they include at least partial coupling 7 of the first heat source 1 thus making it possible to increase the enthalpy of the fluid in the reservoir 105.

The regulation device comprises elements for removing energy, preferably thermal, from the tank 105 intended to reduce the pressure of the tank and suck the working fluid from the fluidic circuit towards the tank. The energy removal elements reduce the enthalpy of the tank 105, the temperature of the fluid in the tank 105 as well as the pressure decreases while the density increases which induces the displacement of the working fluid of the fluidic circuit and more precisely the pipe pump 113 towards the reservoir 105. The removal of the working fluid from the fluidic circuit is done passively by suction without the action of a mechanical member at the level of the tapping pipe 114. The working fluid sucked from the fluidic circuit is at the liquid state.

The energy withdrawal elements can be various as illustrated in figures 8 to 10 .

According to a first embodiment illustrated in figure 8 , they comprise a module for rejecting working fluid in the gaseous state contained in the tank 105 towards the inlet 21 of the second exchanger 102. The rejection module comprises a pipe 115 for rejecting working fluid fluidly connected to a first end to the tank 105 and a second end to the inlet 21 of the second exchanger 102. The fluid evacuated from the tank and injected into the inlet 21 of the second exchanger 102 is in the gaseous state. Preferably, the module comprises an injector or ejector 9 and/or a pump and/or a valve, intended to control the rejection of the working fluid.

According to a second embodiment illustrated in Figure 9 , they include a working fluid injection module, in the reservoir 105, taken from the outlet 42 of the pump 104. The injection module comprises a working fluid injection line 117 fluidly connected to a first end at the outlet 41 of the pump 104 and at a second end at the reservoir 105. The working fluid taken and injected into the reservoir is in the state of expanded liquid. Preferably, the module comprises an injector 8 and/or a valve, intended to control the injection of working fluid.

According to a third embodiment illustrated in Figure 10 , they include at least partial coupling 10 of the second heat source 2, thus making it possible to reduce the enthalpy of the fluid in the reservoir 105.

The variations in the circulating fluid load due to withdrawals and rejections due to the energy supply and withdrawal elements are minimal, punctual and have no synergistic influence with the suction or injection of fluid. work to and from tank 105.

According to a particular embodiment, the temperature of the hot source 1 is less than 200°C and preferably less than 150°C and the temperature of the cold source 2 is less than 50°C and preferably of the order of 20°C. Preferably, the temperature of the cold source 2 is higher than the ambient temperature and more generally of the order of the ambient temperature.

For the first exchanger 101, that is to say the hot exchanger, the maximum temperature is that of the outlet 32 of the expander 103, that is to say a little less than 150°C. The minimum temperature is that of outlet 42 of pump 104, that is to say a little higher than the ambient temperature.

For the second exchanger 102, that is to say the cold exchanger, the maximum temperature is that of the outlet of the turbine or other expander 103, that is to say intermediate, between the temperatures of the hot sources (150°C) and cold (20°C). The minimum temperature of the second exchanger 102 is that of the temperature of the cold source, that is to say, generally the ambient temperature.

A system according to the invention further comprises a self-regulation module 200 illustrated in figures 11 to 13 intended to regulate the pressurization and depressurization of the tank 105 to control the fluid charge circulating in the fluid circuit. The self-regulation module 200 is mechanically operated allowing fully automatic and mechanical regulation.

The self-regulation module 200 illustrated in Figure 13 comprises a compensated regulator 201 coupled to a compensated valve 203.

The self-regulation module 200 is configured to prevent the valve 203 and the regulator 201 from being in the open position simultaneously.

The regulator 201 and the valve 203 are arranged in a housing 205. The regulator 201 is associated with a spring 202 having stiffness Kd while the valve 203 is associated with a spring 204 having stiffness Ks. The stiffness Kd of the spring 202 of regulator 201 is less than the stiffness Ks of the spring 204 of valve 203.

The box 205 is configured to manage pressure differentials to regulate the fluid charge circulating in the fluid circuit. The box 205 is fluidly connected to the elements whose pressure must be controlled. According to the invention, the self-regulation module 200 is associated with the device for regulating the fluid charge circulating in the fluid circuit, the housing 205 is connected to the device for regulating the fluid charge and more precisely to the fluid supply elements. energy and energy withdrawal. In particular according to the embodiment in which the energy supply element comprises a module for injecting the working fluid taken at the outlet 12 of the first exchanger 101 and the energy withdrawal element comprises a rejection module of the working fluid in the gaseous state 4 out of the tank 105 towards the inlet 21 of the second exchanger 102 or a working fluid injection module taken from the inlet 41 of the pump 104.

The box 205 is fluidly connected to the tank 105, preferably it is connected directly by a pipe so as to be subjected to the pressure of the reservoir Pr. The pressure of the reservoir Pr is exerted on the regulator 201 and the valve 203. The housing 205 includes a first opening 206 allowing the fluid connection of the reservoir 105 with the self-regulation module 200.

The housing 205 is fluidly connected to a means of producing a control pressure Pc corresponding preferentially to the saturation pressure of the working fluid at the inlet 41 of pump 104. The control pressure Pc is exerted on the regulator 201 and the valve 203. The housing 205 includes a second opening 207 allowing the fluid connection of the control pressure with the self-regulation module 200.

The control pressure Pc and the tank pressure Pr are relatively opposed to each other with respect to the valve 203 and the regulator 201. That is to say, the control pressure Pc and the tank pressure Pr exert opposing forces on the valve 203 and the regulator 201.

The box 205 is fluidly connected to the fluidic circuit, precisely at the outlet 12 of the first exchanger 101, preferably it is connected directly by a pipe 116. A first end of the pipe 116 is connected to the outlet 12. The box 205 comprises a third opening 208 allowing the fluid connection of the second end of the pipe 116 with the self-regulation module 200.

The housing 205 is fluidly connected to the fluidic circuit, precisely to the inlet 41 of the pump 104, preferably it is connected directly by a pipe 117. A first end of the pipe 117 is connected to the inlet 41 of pump 104. The housing 205 includes a fourth opening 209 allowing the fluid connection of the second end of the pipe 117 with the self-regulation module 200.

Alternatively, the box 205 is fluidly connected to the fluidic circuit, precisely to the inlet 21 of the second exchanger 102, preferably it is connected directly by a pipe 115. A first end of the pipe 115 is connected to the inlet 21. The housing 205 includes a fourth opening 209 allowing the fluid connection of the second end of the pipe 117 with the self-regulation module 200.

There Figure 14 illustrates different cases of self-regulation of the fluid charge circulating in the fluid circuit.

The stiffness of the regulator spring Kd is less than the stiffness of the valve spring Ks. First case (301), when the tank pressure Pr is greater than the sum of the control pressure Pc and the stiffness of the valve spring Ks In this case, the tank pressure Pr is also greater than the sum of the control pressure Pc and the regulator stiffness Kd. Thus, the force exerted by the pressure of the reservoir Pr by the first opening 206 of the housing 205 on the regulator 201 and the valve 203 is greater than the force of the control pressure Pc exerted by the second opening 207 of the housing 205 on the regulator 201 and the valve 203. The stiffness of the regulator and valve springs Kd and Ks do not compensate for this differential inducing the opening of the valve 203 (304) and maintaining the regulator 201 closed.

The opening of the valve 203 means that the fourth opening 209 of the housing 205 is open, allowing, depending on the embodiment, either the working fluid taken from the inlet 41 of the pump 104 to enter the reservoir, or to exit the reservoir 105. the working fluid in the gaseous state towards the inlet 21 of the second exchanger 102.

This movement of fluid causes a drop in pressure (307) in the reservoir 105 generating a suction 120 of working fluid towards the reservoir from the fluid circuit. Reducing the quantity of working fluid in the fluid circuit makes it possible to reduce the pressure at the pump inlet and therefore the subcooling limiting the degradation of the performance of the Rankine machine.

The reservoir pressure Pr having decreased, it is now in the second case (302), i.e. lower than the sum of the control pressure Pc and the stiffness of the valve spring Ks and remains greater than the sum of the control pressure Pc and the regulator stiffness Kd.

Thus, the force exerted by the pressure of the reservoir Pr by the first opening 206 of the housing 205 on the regulator 201 and the valve 203 is greater than the force of the control pressure Pc exerted by the second opening 207 of the housing 205 on the regulator 201 and valve 203. Stiffness regulator and valve springs Kd and Ks compensate for this differential now closing the valve 203 and the regulator 201 (305).

The regulator 201 and the valve 203 being closed, there is no circulation of fluid either at the level of the self-regulation module 200 or between the reservoir 105 and the fluid circuit.

When the tank pressure decreases, the tank pressure Pr is less than the sum of the control pressure Pc and the valve spring rate Ks and the sum of the control pressure Pc and the regulator spring rate Kd (303).

The force exerted by the pressure of the reservoir Pr by the first opening 206 of the housing 205 on the regulator 201 and the valve 203 is greater than the force of the control pressure Pc exerted by the second opening 207 of the housing 205 on the regulator 201 and the valve 203.. The stiffness of the regulator and valve springs Kd and Ks do not compensate for this differential inducing the opening of the regulator 201 (306) and keeping the valve 203 closed.

The opening of the regulator 201 means that the third opening 208 of the housing 205 is open allowing the working fluid taken at outlet 12 of the first exchanger 101 to enter the tank. This movement of fluid causes an increase in pressure (309) in the reservoir Pr generating an injection 121 of working fluid towards the fluidic circuit from the reservoir 105. Increasing the quantity of working fluid in the fluidic circuit makes it possible to increase the pressure at the inlet 41 of pump 104 and therefore the subcooling limiting the risks of cavitation.

The control pressure Pc is transmitted to the self-regulation module 200 at the second opening 207 by a module for producing a control pressure.

Several variants are possible for the control pressure production module. Two of them are illustrated in figures 11 and 12 .

There Figure 12 indicates that the control pressure is transmitted by a production module of the gas source type whose pressure is regulated. To regulate the cavitation margin at inlet 41 of pump 104, the module includes measuring means such as sensors for variables at input 41 of pump 104 such as temperature and pressure and means for regulating the control pressure Pc as a function of these variables. In this case, the self-regulation module 200 is configured to ensure that the separation between the second opening 207 and the rest of the module 200 is hermetic so as to ensure that there is no contamination of the working fluid. not the gas from the production module of the control pressure.

There Figure 12 furthermore illustrates part of the fluidic circuit of the system according to the invention with the pump 104, the first exchanger 101, the second exchanger 102, the reservoir 105, the self-regulation module 200. Between the outlet 22 of the second exchanger 102 and the outlet 12 of the first exchanger 101, are arranged in the direction of circulation of the working fluid, the tapping pipe 114 of the tank 105, the pump 104, the injection pipe 117 of the energy withdrawal element, the first exchanger 101 and the injection pipe 116 of the energy supply element.

• au réservoir 105 par la première ouverture 206,
• à l'élément d'apport d'énergie du dispositif de régulation de la charge fluidique, étant dans ce cas-là un module d'injection de fluide dans le réservoir 105 prélevé en sortie 12 du premier échangeur 101, la sortie 12 étant directement raccordée à la troisième ouverture 208 du module d'autorégulation 200 par la conduite 116,
• à l'élément de retrait d'énergie du dispositif de régulation de la charge fluidique, étant dans ce cas-là un module d'injection de fluide dans le réservoir prélevé en entrée 41 de la pompe 104, l'entrée 41 étant directement raccordée à la quatrième ouverture 209 du module d'autorégulation 200 par la conduite 117.

The self-regulation module 200 being fluidly connected via these different openings:

• to the tank 105 through the first opening 206,
• to the energy supply element of the fluid load regulation device, being in this case a fluid injection module in the reservoir 105 taken from the outlet 12 of the first exchanger 101, the outlet 12 being directly connected to the third opening 208 of the self-regulation module 200 via line 116,
• to the energy removal element of the fluid load regulation device, being in this case a fluid injection module in the reservoir taken from the inlet 41 of the pump 104, the inlet 41 being directly connected at the fourth opening 209 of the self-regulation module 200 via line 117.

There Figure 11 indicates that the control pressure is transmitted by a particular production module. The production module comprises a balloon 210 filled with working fluid thus limiting the risks of contamination, fluidly connected to the second opening 207 of the self-regulation module 200. Preferably, the balloon 210 is maintained at saturation temperature of the fluid at inlet 41 of pump 104. For this purpose, the balloon 210 is advantageously immersed in the working fluid circulating in the fluid circuit. Preferably, the tank 210 is arranged at the outlet 22 of the second exchanger 102. In this way, the control pressure Pc is equal to the pressure of the fluid in the tank 201, itself equal to the saturation pressure of the fluid circulating in the pump line 113, that is to say at the saturation pressure at the inlet 41 of pump 104.

There Figure 11 furthermore illustrates part of the fluidic circuit of the system according to the invention with the pump 104, the first exchanger 101, the second exchanger 102, the reservoir 105, the self-regulation module 200. Between the outlet 22 of the second exchanger 102 and the inlet 21 of the second exchanger 101, are arranged in the direction of circulation of the working fluid, the balloon 210 plunging into the pump pipe 113, the tapping pipe 114 of the tank 105, the pump 104, the first exchanger 101, the injection pipe 116 of the energy supply element, the expander (not shown) then the rejection pipe 115 of the energy withdrawal element.

• au réservoir 105 par la première ouverture 206,
• à l'élément d'apport d'énergie du dispositif de régulation de la charge fluidique, étant dans ce cas-là un module d'injection de fluide dans le réservoir prélevé en sortie 12 du premier échangeur 101, la sortie 12 étant directement raccordée à la troisième ouverture 208 du module d'autorégulation 200 par la conduite 116,
• à l'élément de retrait d'énergie du dispositif de régulation de la charge fluidique, étant dans ce cas-là un module de réjection de fluide à l'état gazeux du réservoir vers l'entrée 21 du deuxième échangeur 102, l'entrée 21 étant directement raccordée à la quatrième ouverture 209 du module d'autorégulation 200 par la conduite 115.

The self-regulation module being fluidly connected via these different openings:

• to the tank 105 through the first opening 206,
• to the energy supply element of the fluid load regulation device, being in this case a fluid injection module in the reservoir taken at outlet 12 of the first exchanger 101, outlet 12 being directly connected at the third opening 208 of the self-regulation module 200 via line 116,
• to the energy removal element of the fluid load regulation device, being in this case a module for rejecting fluid in the gaseous state from the reservoir towards the inlet 21 of the second exchanger 102, the inlet 21 being directly connected to the fourth opening 209 of the self-regulation module 200 via line 115.

The principle underlying the invention provides numerous advantages and in particular that of being able to better control the load of the fluid and therefore the subcooling, so that it is neither too small (risk of cavitation) nor too large (degradation of overall cycle performance).

An additional advantage of the invention is also to reduce the risk of cavitation in the pump. The inlet pressure into the pump is regulated in the case of the invention. Indeed, the cavitation margin for a given installation is expressed by the difference between the inlet pressure minus the saturated vapor pressure and a characteristic value of the pump (NPSH: net positive suction head).

Processes for generating electrical energy in the electrical industry or in that of transformation (metallurgy, chemistry, papermaking, cement works, agro-food) with thermal discharges including at low temperatures, transport with thermal engine (truck, automobile , boat, train), concentrated solar power, geothermal energy and even biomass.

As a non-limiting example

• Fluide de travail : R134a
• Température de sortie condenseur 102 : 20 °C
• Température de sortie évaporateur 101 : 100 °C
• NPSH requis à la pompe 104 : 0.5 bar
• Pression de sortie pompe 104 : 35 bars

For an ORC cycle with the following characteristics:

• Working fluid: R134a
• Condenser outlet temperature 102: 20 °C
• Evaporator outlet temperature 101: 100 °C
• NPSH required at pump 104: 0.5 bar
• Pump 104 outlet pressure: 35 bars

In the case of the Figure 11 with depressurization by vapor rejection. The control pressure Pc is equal to the saturation pressure at inlet 41 of pump 104. We therefore choose a regulator spring stiffness Kd corresponding to a pressure equal to the required NPSH, i.e. 0.5 bar. If we want a hysteresis of 0.5 bar, we choose a valve spring stiffness Ks with a pressure equivalent of 0.5 bar greater than Kd, i.e. 1 bar.

• Température en entrée pompe, et dans le ballon : 20°C soit une pression de saturation de 5.71 bars. Donc Pc = 5.71 bars.
• Pression en entrée pompe correspondant à un NPSH de 0.5 bar, donc Pr = 5.71 +0.5 = 6.21 bars
• Température dans le réservoir (saturation) = 22.7°C

Equilibrium :

• Temperature at pump inlet, and in the tank: 20°C, i.e. a saturation pressure of 5.71 bars. So Pc = 5.71 bars.
• Pump inlet pressure corresponding to an NPSH of 0.5 bar, therefore Pr = 5.71 +0.5 = 6.21 bars
• Temperature in the tank (saturation) = 22.7°C

• Température en entrée 41 de pompe 104 et dans le ballon 210 : 22°C, soit une pression de saturation de 6.08 bars. Donc Pc = 6.08 bars.
• Comme Pr (6.21 bars) < Pc (6.08 bars) + Kd (0.5 bar), le détendeur 201 s'ouvre et permet l'injection de fluide haute température dans le réservoir 105.
• Du fluide est injecté dans le circuit fluidique de l'ORC, la pression dans la conduite d'entrée pompe 113 et dans le réservoir augmente jusqu'à Pr = Pc + Kd = 6.58 bars.
• Les conditions en entrée 41 de pompe 104 donnent un NPSH de 0.5 bar.
• Température dans le réservoir 105 (saturation) = 24.7°C

Case of an increase in temperature at the condenser outlet 102 from 20°C to 22°C:

• Temperature at inlet 41 of pump 104 and in tank 210: 22°C, i.e. a saturation pressure of 6.08 bars. So Pc = 6.08 bars.
• As Pr (6.21 bars) < Pc (6.08 bars) + Kd (0.5 bar), the regulator 201 opens and allows the injection of high temperature fluid into the tank 105.
• Fluid is injected into the fluid circuit of the ORC, the pressure in the pump inlet line 113 and in the tank increases to Pr = Pc + Kd = 6.58 bars.
• The conditions at inlet 41 of pump 104 give an NPSH of 0.5 bar.
• Temperature in tank 105 (saturation) = 24.7°C

• Température en entrée 41 de pompe 104 et dans le ballon 210 : 18°C, soit une pression de saturation de 5.37 bars. Donc Pc = 5.37 bars.
• Comme Pr (6.58 bars) < Pc (5.37 bars) + Ks (1 bar), la soupape 203 s'ouvre et permet la réjection de vapeur du réservoir 105 vers le condenseur 102.
• Du fluide est aspiré à la sortie du condenseur 102 et entre dans le réservoir 105. La pression dans la conduite entrée 41 de pompe 104 et dans le réservoir 105 baisse jusqu'à Pr = Pc + Ks = 6.37 bars.
• Les conditions en entrée 41 de pompe 104 donnent un NPSH de 1 bar.
• Température dans le réservoir 105 (saturation) = 23.7°C

Case of a drop in temperature at the condenser outlet 102 from 22°C to 18°C:

• Temperature at inlet 41 of pump 104 and in tank 210: 18°C, i.e. a saturation pressure of 5.37 bars. So Pc = 5.37 bars.
• As Pr (6.58 bars) < Pc (5.37 bars) + Ks (1 bar), valve 203 opens and allows the rejection of vapor from tank 105 to condenser 102.
• Fluid is sucked in at the outlet of the condenser 102 and enters the tank 105. The pressure in the inlet line 41 of pump 104 and in the tank 105 drops to Pr = Pc + Ks = 6.37 bars.
• The conditions at inlet 41 of pump 104 give an NPSH of 1 bar.
• Temperature in tank 105 (saturation) = 23.7°C

REFERENCES

1.

First heat source

2.

Second heat source colder than the first

3.

Working fluid in liquid state

4.

Working fluid in gaseous state

5.

Heating rods

6.

High temperature fluid injector

7.

By pass of the first heat source

8.

Low temperature fluid injector

9.

Fluid ejector in gaseous state

10.

By pass of the second heat source

11.

First interchange entrance

12.

First exchanger exit

21.

Second interchange entrance

22.

Second exchanger exit

31.

Expander input

32.

Expander output

41.

Pump inlet

42.

Pump output

100.

Rankine Cycle

101.

First interchange

102.

Second interchange

103.

Expander

104.

Pump

105.

Reservoir

110.

First exchanger pipe

111.

Expander line

112.

Second exchanger line

113.

Pump line

114.

Tank connection line

115.

Fluid rejection line in gaseous state

116.

High temperature fluid injection line

117.

Low temperature fluid injection line

120.

Smooth suction

121.

Fluid injection

200.

Self-regulation module

201.

Regulator

202.

Regulator spring

203.

Valve

204.

Valve spring

205.

Housing

206.

First opening

207.

Second opening

208.

Third opening

209.

Fourth opening

210.

Ball

300.

Reservoir pressure

301.

Reservoir pressure greater than the sum of the control pressure and the valve spring rate

302.

Reservoir pressure greater than the sum of the control pressure and the regulator spring rate, but less than the sum of the control pressure and the valve spring rate.

303.

Reservoir pressure less than the sum of the control pressure and the regulator spring rate

304.

Valve opening

305.

Valve and regulator closing

306.

Regulator opening

307.

Tank pressure decreases

308.

Constant tank pressure

309.

Tank pressure increases

Pr.

Reservoir pressure

Pc.

Pressure control

Kd.

Regulator spring stiffness

Ks.

Valve spring stiffness

Claims (17)

1. System for producing electrical or mechanical energy comprising a fluid circuit, wherein a working fluid circulates, comprising a plurality of members passed through by the working fluid and among which:

   - at least one heat exchanger (101) configured to be thermally coupled to at least one first heat source (1),

   - an expander (103), an inlet (31) of which is fluidically connected to an outlet (12) of the first exchanger (101),

   - a second heat exchanger (102) configured to be thermally coupled to a second heat source (2), colder than the first heat source (1),

   - at least one pump (104) configured to move the working fluid in the fluid circuit,

   - at least one reservoir (105) receiving the working fluid and arranged between the second exchanger (102) and the pump (104) on a tapping duct (114),

   the fluid circuit being configured such that the working fluid passes successively through at least the pump (104), the first exchanger (101), the expander (103) and the second exchanger (102), then the pump (104) again,

   where the system comprises a device for regulating the fluid load circulating in the fluid circuit configured to operate in a closed circuit with the fluid circuit and for maintaining saturation conditions in the reservoir (105), such that the reservoir (105) contains the working fluid simultaneously to the liquid state (3) and to the gaseous state (4), the regulation device comprising thermal energy input elements (5, 6, 7) in the reservoir (105) intended to increase the pressure of the reservoir (Pr) and to induce the injection of the working fluid of the reservoir in the fluid circuit and energy removal elements (8, 9, 10) of the reservoir (105) intended to decrease the pressure of the reservoir (Pr) and to induce the suctioning towards the reservoir (105) of the working fluid outside of the fluid circuit,

   and where the system comprises a mechanically operating self-regulation module intended to regulate the pressurising and the depressurising of the reservoir (105) and comprising a casing (205) receiving a regulator (201) associated with a regulator spring (202) and a valve (203) associated with a valve spring (204).
2. System according to the preceding claim, wherein the reservoir (105) is directly connected to the tapping duct (114) which is itself directly connected to the fluid circuit between the second exchanger (102) and the pump (104), advantageously, the system does not comprise fluid other than the working fluid.
3. System according to any one of the preceding claims, wherein the thermal energy input elements comprise at least one heating rod (5) immersing into the reservoir (105), and/or a module for injecting, into the reservoir (105), working fluid removed at the outlet (12) of the first exchanger (101), and/or a coupling (7), at least partial, of the reservoir (105) with the first heat source (1).
4. System according to any one of the preceding claims, wherein the energy removal elements comprise a module for ejecting, outside of the reservoir (105), the working fluid in the gaseous state (4) in the direction of the inlet (21) of the second exchanger (102) and/or a module for injecting, into the reservoir (105), working fluid removed at the outlet (42) of the pump (104), and/or an at least partial coupling (10) of the reservoir (105) with the second heat source (2).
5. System according to any one of the preceding claims, wherein the self-regulation module comprises a compensated regulator (201) coupled to a compensated valve (203).
6. System according to any one of the preceding claims, wherein the thermal energy input elements comprise a module for injecting, into the reservoir (105), working fluid removed at the outlet (12) of the first exchanger (101) and the energy removal elements comprise a module for ejecting fluid in the gaseous state (4), outside of the reservoir (105), in the direction of the inlet (21) of the second exchanger (102) or a module for injecting, into the reservoir (105), working fluid removed at the outlet (42) of the pump (104).
7. System according to the preceding claim, wherein the casing (205) comprises a first opening (206) fluidically connected to the reservoir (105) so as to be subjected to the pressure of the reservoir Pr, a second opening (207) fluidically connected to a control pressure production module, so as to be subjected to a controlled pressure Pc, a third opening (208) for injecting, into the reservoir (105), working fluid removed at the outlet (12) of the first exchanger (101), a fourth opening (209) for injecting, into the reservoir (105), working fluid removed at the outlet (42) of the pump (104) or ejecting, outside of the reservoir (105), working fluid in the gaseous state (4) to the inlet (21) of the second exchanger (102).
8. System according to the preceding claim, wherein the control pressure Pc is equal to the saturation pressure of the fluid at the pump (104) inlet (41), during the operation of the system.
9. System according to any one of the three preceding claims, wherein the valve spring (204) has a stiffness Ks greater than that of the regulator spring (202).
10. System according to the preceding claim, wherein the self-regulation module (200) is configured to be balanced, with the regulator (201) closed and the valve (203) closed, when the pressure of the reservoir Pr is both greater than the sum of the control pressure Pc and of the stiffness Kd of the spring of the regulator (202), and less than the sum of the control pressure Pc and of the stiffness Ks of the spring of the valve (204).
11. System according to any one of the two preceding claims, wherein the self-regulation module (200) is configured such that the opening of the valve (203) fluidically connects the reservoir (105) and the inlet (21) of the second exchanger (102) or the outlet (42) of the pump (104) by the fourth opening (209).
12. System according to any one of the three preceding claims, wherein the self-regulation module (200) is configured such that the opening of the regulator (201) fluidically connects the reservoir (105) and the outlet (12) of the first exchanger (101) by the third opening (208).
13. System according to any one of the six preceding claims, wherein the control pressure production module comprises a ball (210) filled with working fluid fluidically connected to the second opening (207) of the casing (205), the ball (210) being arranged to immerse in the working fluid of the fluid circuit at the outlet (22) of the second exchanger (102), such that the temperature of the fluid contained in the ball (210) is identical to that of the working fluid of the fluid circuit at the pump (104) inlet (41).
14. System according to any one of claims 7 to 12, wherein the control pressure production module comprises a regulated pressure gas source fluidically connected to the second opening (207) of the casing (205), pressure sensors and/or temperature at the pump (104) inlet (41) and gas source pressure regulation means so as to define a control pressure Pc.
15. Method for regulating the fluid load circulating in the fluid circuit of an energy production system according to any one of the preceding claims, comprising the following steps:

    - a step of increasing pressure of the working fluid through the pump (104),

    - a step of heating the working fluid through the first heat exchanger (101),

    - a step of regulating the working fluid coming from the first exchanger (101) through the expander (103),

    - a step of cooling the working fluid through the second heat exchanger (102),

    where it comprises:

    - a step of maintaining saturating conditions in the reservoir (105) to maintain the working fluid simultaneously in two gaseous (4) and liquid (3) states in the reservoir (105) by:

    - a step of inputting thermal energy in the reservoir (105) comprising the increase of pressure in the reservoir (105) and the addition of working fluid in the fluid circuit by injecting from the reservoir (105),

    - or alternatively a step of removing energy outside of the reservoir (105) comprising the decrease of pressure in the reservoir (105) and the removal of working fluid from the fluid circuit by suctioning to the reservoir (105),

    - and where it comprises a self-regulation step intended to regulate the pressurising and the depressurising of the reservoir (105), such that when balanced, the regulator (201) and the valve (203) are closed when the pressure of the reservoir Pr is both greater than the sum of the control pressure Pc and of the stiffness Kd of the spring of the regulator (202) and less than the sum of the control pressure Pc and of the stiffness Ks of the spring of the valve (204).
16. Method according to the preceding claim, combined with claims 7 and 9 comprising, when the pressure of the reservoir Pr is greater than the sum of the control pressure Pc and of the stiffness Ks of the spring (204) of the valve (203), the opening of the valve (203) fluidically connecting the reservoir (105) and the inlet (21) of the second exchanger (102) or the outlet (42) of the pump (104) by the fourth opening (209) so as to decrease the pressure of the reservoir Pr.
17. Method according to any one of the two preceding claims, combined with claims 7 and 9, comprising when the pressure of the reservoir Pr is less than the control pressure Pc added to the stiffness Kd of the regulator spring (202), the opening of the regulator fluidically connecting the reservoir (105) and the outlet (12) of the first exchanger (101) by the third opening (208) so as to increase the pressure of the reservoir Pr.

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