EP4116640B1 - System for producing cold and electricity from a low temperature heat source, allowing adjustment of the ratio between production of cold and of electricity. - Google Patents

Description

Technical area

The present invention relates to the field of thermodynamic systems for the co-production of electrical energy and thermal energy, more particularly cold, from a low-temperature thermal source.

The applications of the invention are numerous, among which mention may be made of the field of stationary systems, with heat sources such as heat discharges from industrial processes, solar thermal, biomass, geothermal energy, gas turbines.

Prior technique

Current energy policies pose the problem of managing the fluctuation or intermittence of sources, but also of controlling the variability of energy demand peaks, while promoting low thermal level heat sources, typically from 80 to 150°C, such as solar thermal, abundant waste heat but with low exergy content.

In addition, particular vigilance is to be paid to the production of cold and electricity, stationary energy demands which are growing rapidly and which are usually responsible for high greenhouse gas emissions, in particular during peaks in demand.

This problem is particularly significant for the mobility sector because it is responsible for a large part of the energy consumption and the emission of greenhouse gases both for the propulsion itself and for the on-board systems (cold).

1. A/ pouvoir générer du froid à partir d'une source de chaleur à basse température, éventuellement fluctuante, voire intermittente;
2. B/ pouvoir produire de l'électricité à partir d'une source de chaleur à basse température, éventuellement fluctuante, voire intermittente ;
3. C/ pouvoir produire de façon concomitante du froid et de l'électricité à partir d'une source de chaleur à basse température, éventuellement fluctuante, voire intermittente;
4. D/ pouvoir réguler de manière très précise et efficace le rapport entre production de froid et production électrique, et ce de préférence de manière continue (fonction D0).

In fact, to meet these needs, the functional specifications of the systems, which the inventors have formulated, can be summarized as follows:

1. A/ being able to generate cold from a low-temperature, possibly fluctuating or even intermittent heat source;
2. B/ be able to produce electricity from a low-temperature, possibly fluctuating or even intermittent heat source;
3. C/ being able to simultaneously produce cold and electricity from a low-temperature, possibly fluctuating or even intermittent heat source;
4. D/ be able to very precisely and efficiently regulate the ratio between cold production and electrical production, preferably continuously (function D0).

No thermodynamic cycle as such can, alone, achieve all of these functionalities.

Ammonia-water absorption systems have advantages that have already been clearly identified, such as allowing negative temperatures to be reached as well as the use of pressures higher than ambient, compared to H ₂ O-LiBr absorption cycles. Furthermore, such systems do not include any fluid that could contribute to the destruction of the ozone layer or to the increase of the greenhouse effect, as is the case with most organic fluids used in refrigeration.

In addition, hybrid systems for the co-production of electricity and cooling have already been conceptualized.

We thus know from publication [1] a system of co-production of electricity and cold with an internal exchanger. To do this, the operation of the system is based on a cycle that combines a Rankine cycle and a cold production cycle by absorption. The various components of the system are arranged in series in a closed fluidic circuit. The system described in this publication does not allow the electricity and cold production conditions to be varied. The production of cold and the production of electricity are always simultaneous.

• de l'importance des fuites conduisant à des pertes pour de très petits débits dans un expandeur de type machine volumétrique, telle qu'un dispositif dénommé « scroll » en langage anglo-saxon ;
• du comportement hors nominal pour un expandeur de type turbomachine, par exemple une turbine axiale, qui implique une relation précise entre débit et pression d'entrée dans l'expandeur.

We also know from the publication [2] and the request for patent EP3748274A1 , a thermal energy and electrical energy production system comprising an absorption device comprising an absorber, a generator, a condenser, an evaporator and a fluidic absorption circuit able to receive a working solution comprising a refrigerant and an absorbent, preferably the couple ammonia/water (NH3/H2O), the fluidic circuit connecting the generator to the condenser, the condenser to the evaporator, the evaporator to the absorber and the absorber to the generator , the system further comprising a compressor reversible of the turbomachine type in combination with a module for managing the circulation of the refrigerant so as to ensure in a first mode of operation a production of electrical energy alternately with a production of cold or heat, and in a second mode of operation to ensure a production of electrical energy. The system described is compact, with a limited number of components and of reduced cost, which further allows possible integration in non-stationary applications. On the other hand, in this system according to the publication [2] and EP3748274A1 , the aforementioned functions B/ and D/ are not necessarily possible due to:

• the importance of the leaks leading to losses for very small flow rates in an expander of the volumetric machine type, such as a device called “scroll” in Anglo-Saxon language;
• off-nominal behavior for a turbomachine-type expander, for example an axial turbine, which implies a precise relationship between flow rate and inlet pressure in the expander.

Also known from the patent ES2512990B1 a system for the coproduction of electricity and cold comprising, in addition to the traditional components of a system implementing an absorption cycle, an expander and an ejector arranged downstream of the expander, which has no positive impact on the production of electricity. The D/ function is not possible with a system according to ES2512990B1 . Moreover, on reading this document, it is not clear how the flow of the working fluid is divided between cold production and electrical production and whether it is possible to vary the ratio.

Moreover, variable section ejectors have recently been used in mechanical vapor compression cycles, with the aim of improving the performance of these cycles outside the nominal point: see for example the publication [3].

There is therefore a need to propose a system of co-production of cold and electricity which makes it possible to meet all the functions of the specifications as stated above, i.e. functions A/ and D/ and preferably also function D0/.

The patent document EP 3 748 137 A1 and publication [4] also describe cold and electrical energy production systems.

Disclosure of Invention

• un désorbeur, appelé générateur,
• un condenseur,
• un évaporateur,
• un absorbeur,
• un circuit fluidique d'absorption dans lequel circule un fluide de travail comprenant un fluide frigorigène et un absorbant, le circuit fluidique reliant le générateur au condenseur, le condenseur à l'évaporateur, l'évaporateur à l'absorbeur et l'absorbeur au générateur,
• une turbine supersonique agencée sur le circuit fluidique entre le générateur et l'absorbeur en dérivation du condenseur et de l'évaporateur, la turbine étant configurée pour actionner une génératrice électrique pour produire de l'électricité,
• au moins un éjecteur agencé sur le circuit fluidique entre le générateur et la turbine.

To do this, the subject of the invention is a system for producing cold and electrical energy comprising:

• a desorber, called a generator,
• a condenser,
• an evaporator,
• an absorber,
• a fluidic absorption circuit in which circulates a working fluid comprising a refrigerant and an absorbent, the fluidic circuit connecting the generator to the condenser, the condenser to the evaporator, the evaporator to the absorber and the absorber to the generator,
• a supersonic turbine arranged on the fluid circuit between the generator and the absorber by-passing the condenser and the evaporator, the turbine being configured to actuate an electric generator to produce electricity,
• at least one ejector arranged on the fluidic circuit between the generator and the turbine.

By "supersonic turbine" is meant here and in the context of the invention, a turbine whose nominal operating speed is a supersonic flow at high speed.

The ejector can be a simple ejector or with a variable neck section.

By "ejector" is meant here and in the context of the invention, a mechanical assembly exploiting the depression created by the Venturi effect and making it possible to compress a secondary fluid by mixing it with the pressurized primary fluid, the assembly not comprising any moving parts transmitting energy to the fluids.

By “variable neck section ejector” is meant here and in the context of the invention an ejector in which the dimensions of the ejector which are mainly the diameters of the section of the sonic neck and/or of the mixer can be varied.

Advantageously, the working fluid comprises ammonia (NH ₃ ) as refrigerant and water (H ₂ O) as absorbent. Other refrigerant/absorbent pairs may be suitable.

According to an advantageous embodiment variant, the fluid circuit comprises an exchanger arranged on a bypass fluid line, bypassing the fluid connection between the evaporator and the absorber, the bypass line being connected to the fluid injector secondary of the ejector, so that the exchanger heats the secondary fluid before it enters the ejector.

Preferably, the turbine is configured to drive the working fluid circulation pump.

According to an advantageous embodiment, the system comprises a refrigerant rectifier, arranged between the generator and the condenser.

According to this mode and an advantageous variant, the flows of so-called rich and lean solutions of the working fluid are separated at the output of the generator or at the output of the rectifier.

According to another advantageous variant, the fluid at the outlet of the working fluid circulation pump is used as the cold source of the rectifier.

According to another advantageous embodiment, the system comprises a bypass fluidic line between the ejector and the absorber, so as to increase the pressure of the working fluid in the latter.

Advantageously, the system comprises, as heat source, low temperature heat advantageously between 70°C and 150°C.

• dans un premier mode de fonctionnement de production de froid seule, circulation du fluide de travail dans le circuit fluidique successivement au travers du générateur, du condenseur, de l'évaporateur puis de l'absorbeur puis à nouveau dans le générateur;
• dans un deuxième mode de fonctionnement de production d'énergie électrique seule, circulation du fluide de travail dans le circuit fluidique successivement au travers du générateur, de la turbine supersonique associée à une génératrice électrique, de l'absorbeur puis à nouveau dans le générateur;
• dans un troisième mode de fonctionnement de co-production de froid et d'énergie électrique, circulation d'une partie du fluide de travail dans le circuit fluidique successivement au travers du générateur, du condenseur, de l'évaporateur puis de l'absorbeur puis à nouveau dans le générateur et de l'autre partie du fluide de travail successivement au travers du générateur, de la turbine supersonique associée à une génératrice électrique, de l'absorbeur puis à nouveau dans le générateur;
• dans un quatrième mode de fonctionnement de co-production de froid et d'énergie électrique avec un rapport régulé entre production de froid et production électrique, circulation d'une partie du fluide de travail dans le circuit fluidique successivement au travers du générateur, du condenseur, de l'évaporateur puis de l'absorbeur puis à nouveau dans le générateur et de l'autre partie du fluide de travail successivement au travers du générateur, de l'éjecteur, de la turbine supersonique associée à une génératrice électrique, de l'absorbeur puis à nouveau dans le générateur.

Another subject of the invention is a method for producing electrical energy and thermal energy implemented by a system as described above comprising:

• in a first operating mode of cold production alone, circulation of the working fluid in the fluidic circuit successively through the generator, the condenser, the evaporator then the absorber then again in the generator;
• in a second operating mode of electrical energy production alone, circulation of the working fluid in the fluidic circuit successively through the generator, the supersonic turbine associated with an electrical generator, the absorber and then again through the generator;
• in a third operating mode of co-production of cold and electrical energy, circulation of part of the working fluid in the fluidic circuit successively through the generator, the condenser, the evaporator then the absorber then again in the generator and the other part of the working fluid successively through the generator, the supersonic turbine associated with an electric generator, the absorber then again in the generator;
• in a fourth operating mode of co-production of cold and electrical energy with a regulated ratio between cold production and electrical production, circulation of part of the working fluid in the fluidic circuit successively through the generator, the condenser, the evaporator then the absorber then again in the generator and the other part of the working fluid successively through the generator, the ejector, the supersonic turbine associated with an electric generator, the absorber then back into the generator.

Another subject of the invention is the use of a system for producing cold and electrical energy as described above for electrical production with a power greater than 100 kWe.

Thus, the invention essentially consists of a system for producing electricity and cold as described in the application EP3748274A1 to choose a supersonic turbine to reduce the leakage rate and guarantee the efficiency of electricity production, and to add a simple or variable-section ejector upstream, making it possible to continuously increase cold production while maintaining the efficiency of electricity production.

To carry out the different operating modes carrying out the functions A/, B/, C/, D/ and D0/, the system comprises a working fluid management module piloting a set of adjustment valves, two expansion valves whose opening is adjustable and controls the speed of the pump according to the fluctuation of the hot source or the needs.

The ejector according to the invention makes it possible to increase the flow rate passing through the cold part of the working fluid circuit, and therefore the cold power produced, while maintaining good electrical production efficiency (function D/).

The D0/ function is ensured by changing the section of the ejector so as to optimize its performance for each operating condition.

• en tant qu'applications stationnaires, la production de froid et d'électricité sur des sources de chaleur à basse température (rejets thermiques sur des procédés industriels, solaire thermique, biomasse, géothermie, turbines à gaz, réseaux) ;
• les applications de transport avec des moteurs à essence, diesel et turbine à gaz ;
• les applications de transport sur des véhicules hybrides et électriques avec des besoins de froid.

Many applications can be envisaged for a system according to the invention, among which we can mention:

• as stationary applications, the production of cold and electricity on low-temperature heat sources (thermal discharges on industrial processes, solar thermal, biomass, geothermal energy, gas turbines, networks);
• transportation applications with gasoline, diesel and gas turbine engines;
• transport applications on hybrid and electric vehicles with cooling needs.

Other advantages and characteristics will emerge better on reading the detailed description, given by way of illustration and not limitation, with reference to the following figures.

Brief description of the drawings

• [ Fig 1 ] there figure 1 represents a general diagram of a system according to the invention.
• [ Fig 2 ] there picture 2 reproduces the diagram of the system according to the figure 1 operating according to an operating mode allowing the production of cold alone from a thermal source.
• [ Fig.3 ] there picture 3 reproduces the diagram of the system according to the figure 1 operating according to an operating mode allowing the production of electrical energy alone from a thermal source.
• [ Fig 4 ] there figure 4 reproduces the diagram of the system according to the figure 1 operating according to an operating mode allowing the simultaneous co-production of electrical energy and cold from a thermal source.
• [ Fig.5 ] there figure 5 reproduces the diagram of the system according to the figure 1 operating according to an operating mode allowing the simultaneous co-production of electrical energy and cold from a thermal source, with the possibility of adjusting the ratio between cold production and electrical production.
• [ Fig 6 ] there figure 6 represents an advantageous layout diagram of an ejector upstream of a supersonic turbine in a system according to the invention.

detailed description

It is specified that throughout the application, the terms “inlet”, “outlet”, “upstream”, “downstream” are to be understood in relation to the direction of circulation of the fluid considered within a system according to the invention.

Also throughout the application, the expression “component C1 fluidically connected to component C2” is synonymous with “C1 is in fluid connection with C2” does not necessarily mean that there is no member between C1 and C2. The expressions "arranged on" or "on" are synonymous with "fluidly connected to".

The term "arranged on" means "in fluidic connection".

All the fluidic connection lines of the fluidic absorption circuit are represented in the set of figures 1 to 5 by solid lines, without numerical reference for purposes of clarity. The direction of fluid circulation within a fluidic line is indicated by the direction of the arrow on this line.

The set of adjustment valves which operate in on/off mode to carry out the various operations of the system according to the invention described with reference to the figures 1 to 5 , is not designated by a reference numeral. On the other hand, when a valve considered is in an off state to carry out one of the operations of the system, it is indicated by the symbol in the form of a cross in the figure considered.

By direct exchange or direct coupling is meant that the exchange of thermal energy takes place directly without any intermediate circuit or component. The direct exchange in the condenser or the evaporator takes place directly between the refrigerant and, for example, an air flow.

The system for producing electrical energy and cold according to the invention, as shown in figure 1 , comprises an absorption machine and a heat source, preferably a low temperature heat source advantageously between 70° C. and 150° C., such as waste heat, which may be fluctuating, such as a solar source or waste heat linked to the start-up of a heat engine or intermittent industrial waste.

An absorption machine uses as a working solution a binary mixture, one of the components of which is more volatile than the other, and constitutes the refrigerant. The refrigerant/absorbent working solution is preferably the ammonia/water (NH ₃ /H ₂ O) couple. The concentrations of the working fluid and the absorbent in the working solution are adapted to the pressure and the temperature of the air treatment and lower than the crystallization concentration of the solution.

The NH ₃ /H ₂ O couple can be used for air conditioning applications, but also for refrigeration and there is no possible crystallization on the operating ranges in pressure and temperature. On the other hand, for this couple, the difference in vapor pressure between the absorbent and the refrigerant is low. There are therefore traces of water taken away with the ammonia vapor at the outlet of the generator 1 sometimes requiring the presence of a rectifier 13.

The absorption machine comprises a set of four main exchangers, namely a generator 1, a condenser 2, an evaporator 3 and absorber 4, and preferably at least one secondary exchanger. The four secondary exchangers illustrated, namely a subcooler 6, an economizer 8, a rectifier 13, or an exchanger 14, make it possible to improve the performance of the machine.

The absorption machine further comprises at least one solution pump 9 and an expansion valve 10 of a loop 11 and an expansion valve 12. The machine operates at three temperature levels: a low temperature level corresponding to the production of cold at the evaporator 3, an intermediate temperature level corresponding to the temperature of condensation of the refrigerant fluid, but also to that of absorption of the refrigerant fluid by the absorbent and a high temperature level corresponding to the driving temperature of the generator 1.

The absorption machine comprises a fluidic absorption circuit 100 configured to ensure the fluidic connection of the various components of the system and in particular of the absorption machine. The absorption fluidic circuit 100 is a closed circuit intended to receive the working solution.

The absorption machine operates at high pressure between pump 9 upstream of generator 1 and expansion valve 12, downstream of condenser 2, and at low pressure between expansion valve 2, downstream of condenser 2 and pump 9 upstream of generator 1.

The generator also commonly called desorber 1 allows the heat exchange between the heat source and the working fluid. Such a generator 1 therefore comprises a hot source inlet and outlet, not shown, allowing the supply of heat necessary for the vaporization of the refrigerant of the working solution. Generator 1 is fluidically connected to condenser 2 and absorber 4.

Preferably, an economizer 8 described below is arranged between generator 1 and absorber 4 to allow the entry of the so-called rich working solution into the generator 1 and the exit of the so-called lean working solution from the generator 1.

The expansion valve 10 allows the pressure of the lean working solution to be released before it is transmitted to the absorber 4.

Preferably, a rectifier 13 is arranged between the generator 1 and the condenser 2. The rectifier 13 possibly makes it possible to rectify the working solution, by removing by condensation the traces of water entrained with the working fluid.

The condenser 2 makes it possible to reject heat from the working fluid towards a source at intermediate temperature, by condensing the vapor of refrigerant fluid. Condenser 2 is fluidically connected to generator 1 and to evaporator 3. The fluidic connection between generator 1 and condenser 2 allows the entry of refrigerant vapor into the latter. The expansion valve 12 brings the refrigerant to its evaporation pressure and therefore allows the exit from the condenser 2 of the refrigerant in the liquid state. Condenser 2 also includes a cooling source such as air circulation to ensure its normal operation. The phase change of the refrigerant from the vapor state to the liquid state is accompanied by a release of heat which is transmitted for example to the circulating air flow. The heated air is exhausted from the system.

The sub-cooler 6 is arranged between the condenser 2 and the evaporator 3, and between the evaporator 3 and the absorber 4, and makes it possible to sub-cool the refrigerant at the inlet of the evaporator 3 and to preheat the refrigerant in the vapor state at the outlet of the evaporator 3. The sub-cooler 6 therefore makes it possible to reduce the dimensions of the condenser 2 and of the evaporator 3 and thus significantly improve the performance of the machine. Preferably, as illustrated, the expansion valve 12 is arranged between the sub-cooler 6 and the evaporator 3.

The evaporator 3 makes it possible to take heat from the cold source in order to vaporize the refrigerant fluid. The evaporator 3 is fluidly connected to the condenser 2 and to the absorber 4. The phase change of the refrigerant from the liquid state to the vapor state within the evaporator 3 is accompanied by a transmission of heat from the hot source to the outlet of the the evaporator 3, to the refrigerant. This hot source transmits calories and thus sees its temperature drop. The evaporator 3 is the location for the production of cold temperatures.

The absorber 4 makes it possible to exchange calories between the working fluid and a source at intermediate temperature, to condense the refrigerant vapor coming from the evaporator 3. The absorber 4 is fluidically connected to the evaporator 3 and to the generator 1 by the loop 11.

The pump 9 of this loop 11 makes it possible to circulate the working solution in the circuit 100. More precisely, the pump 9 is intended to circulate the rich working solution from the absorber 4 in the direction of the generator 1. The pump 9 consumes little electricity.

More precisely still, the pump 9 is fluidically connected to the economizer 8 through which the rich working solution is heated before being transmitted to the generator 1. Conversely, the economizer 8 transmits heat from the lean solution coming from the generator 1 to the rich solution coming from the absorber 4. The absorber 4 is fluidly connected to the generator 1 to allow the entry of the lean working solution coming from the generator 1 into the absorber 4 .

The expansion valve 10 is arranged between the generator 1 and the absorber 4. The phase change of the refrigerant from the vapor state to the liquid state is accompanied by a release of heat which is transmitted to a cooling source such as an air flow. The heated air is exhausted from the system.

According to the invention, a supersonic turbine 5 as an expander driving a generator is arranged between the generator 1 and the absorber 4, by-passing the condenser 2 and the evaporator 3. This supersonic turbine 5 has a reduced leakage rate and it guarantees the efficiency of the electrical production.

Also according to the invention, a single or variable-section ejector 50 is arranged to continuously increase cold production while maintaining the efficiency of electrical production. The ejector 50 can be simple or with variable section, as detailed below. A simple ejector 50 is optimized for a given ratio between cold production and electricity production (function D/), while a variable section ejector 50 allows very precise and efficient regulation for all the ratios between electricity production and cold production (function D0/).

The hydraulic connection allows the entry of the refrigerant in the vapor state from the generator 1 directly into the turbine 5 or indirectly, in bypass mode through the ejector 50.

A superheater 7 is arranged between the generator 1 and the turbine 5, preferably between the ejector 50 and the turbine to allow an additional heat exchange between a hot source, not shown, and the working fluid in order to obtain better quality steam at the inlet of the turbine 5.

The turbine 5 is fluidly connected to the absorber 4 to allow the exit of the refrigerant in the state of expanded vapor from the turbine 5 to the absorber 4 according to a mode of production of electrical energy.

The exchanger 14 is arranged on a fluidic line 15 branching from the fluidic connection between the evaporator 3 and the absorber 4. This fluidic line 15 is connected to the secondary fluid injector (driven) of the ejector 50. Thus, the exchanger 14 makes it possible to heat the secondary fluid before it enters the ejector 50.

The supersonic turbine 5 is advantageously connected to an electric generator which makes it possible to transform the mechanical energy recovered by the turbine 5 into electricity by producing an electric power W _turb .

Typically, the supersonic turbine 5 is configured to allow electrical production greater than 100 kWe, that is to say medium power or even high power of 1 MWe.

The system according to the invention further comprises a module for managing the circulation of the working solution within the circuit 100 and the various components of the system which have just been described. The management module is configured to set system operating conditions based on power requirements and source fluctuations, as detailed below. It can be a production of cold alone, or the production of electrical energy, or a co-production of cold and electrical energy, depending on the temperatures of the sources, the price of electricity, etc.

This management module comprises the adjustment valves (on/off valves not shown), the two expansion valves 10, 12, the opening of which is adjustable and a control unit which controls the speed of the pump 9, in order to allow fine adjustment of the circulation flow rates of the working solution and the refrigerant for the implementation of the system operation modes according to the fluctuation of the hot source or the needs.

The system and the management module according to the invention have the advantage of being compact, advantageously requiring only a few additional components such as valves, possibly temperature and pressure sensors, which reduces the costs and the bulk allowing the system according to the invention to be used in mobile applications.

• Q̇des : puissance du générateur 1 ;
• Qcond : puissance du condenseur 2 ;
• Qévap : puissance de l'évaporateur 3 ;
• Qabs : puissance de l'absorbeur 4 ;
• Wturb : travail de la turbine supersonique 5;
• Qsub : puissance du sous-refroidisseur 6 ;
• QSH : puissance du surchauffeur 7 ;
• QSHX: puissance de l'économiseur 8 ;
• Wpump: travail de la pompe 9 de la solution de travail.
• Qrect: puissance du rectifieur 13;
• QHX: puissance de l'échangeur 14.

The different thermal and electrical powers of the different components of the system are represented on the figures 1 to 5 by the following symbols:

• Q̇des: power of generator 1;
• Qcond: power of condenser 2;
• Qevap: power of evaporator 3;
• Qabs: power of the absorber 4;
• Wturb: work of supersonic turbine 5;
• Qsub: power of subcooler 6;
• QSH: superheater power 7;
• QSHX: power saver 8;
• Wpump: working solution pump 9.
• Qrect: rectifier power 13;
• QHX: power of exchanger 14.

The operation of the system for cold production alone is shown in figure 2 . The working solution circulation management module initiates circulation of the working solution in a conventional absorption cycle. To do this, the module closes the adjustment valves on the fluidic line on either side of the ejector 50 and the turbine 5 as well as on the bypass line 15 upstream of the exchanger 14. The function A/ is thus performed.

We now describe the operation of the system according to the picture 2 to perform this function A/.

The refrigerant in the working solution leaves generator 1 and passes through rectifier 13 before arriving in condenser 2. The refrigerant leaves condenser 2 to pass through subcooler 6, and expansion valve 12, before arriving in evaporator 3. The refrigerant leaves evaporator 3 to pass through subcooler 6 before arriving in absorber 4. The refrigerant gene is absorbed by the absorbent and the so-called rich working solution emerges from the absorber 4 to circulate in the loop 11.

In this loop 11, the rich working solution successively passes through the pump 9 and the economizer 8 before arriving in the generator 1. The lean working solution leaves the generator 1 to pass successively through the economizer 8 and the expansion valve 10 before arriving in the absorber 4. The production of cold thus takes place at the level of the evaporator 3 during the evaporation of the refrigerant which is accompanied by a cooling of the hot source. The cooled hot source can then be used for example for air conditioning.

The operation of the system for electricity production alone is shown in picture 3 . The working solution circulation management module triggers circulation of the working solution following a Rankine cycle, more specifically a Kalina cycle. To do this, the module closes the adjustment valves on the fluidic line on either side of the ejector 50, on the fluidic line between the generator 1 and the rectifier 13 downstream of the bypass of the turbine line 5 as well as on the line between the evaporator 3 and the absorber 4 upstream of the bypass of the turbine line 5. The function B/ is thus performed.

We now describe the operation of the system according to the picture 3 to perform this function B/.

The refrigerant in the working solution leaves the generator 1 and crosses the superheater 7 before arriving in the turbine 5. The refrigerant leaves the turbine 5 to emerge in the absorber 4. The refrigerant is absorbed by the absorbent and the rich working solution leaves the absorber 4 to cross the loop 11 as described with reference to picture 2 before returning to generator level 1. Electricity is produced by turbine 5 connected to an electric generator.

The operation of the system for simultaneous production of cold and electricity is shown in figure 4 .

The working solution circulation management module initiates circulation of the working solution through an absorption cycle and a power generation cycle. To do this, the module only closes the adjustment valves on the fluidic line on either side of the ejector 50. The function C/ is thus performed. Due to the implementation of a supersonic turbine 5, the flow rate is a function of the upstream-downstream pressure jump and thus the ratio between the cold and electrical powers produced is fixed and cannot be changed.

We now describe the operation of the system according to the figure 4 to perform this function C/.

At the outlet of the generator 1, the refrigerant of the working solution is directed partially towards the part of the circuit 100 implementing a cold production cycle and partially towards the other part implementing an electricity production cycle. Part of the refrigerant at the outlet of generator 1 is diverted to supersonic turbine 5 while the other part circulates to condenser 2 by crossing rectifier 13 upstream. The refrigerant leaves condenser 2 to cross sub-cooler 6 and expansion valve 12 before arriving in evaporator 3. the absorber 4. The refrigerant is absorbed by the absorbent and the rich working solution leaves the absorber 4 to circulate in the loop 11 and therefore successively passes through the pump 9, the economizer 8 before arriving in the generator 1. The lean working solution leaves the generator 1 to pass successively through the economizer 8 and the expansion valve 10 before arriving in the absorber 4.

The part of the refrigerant passing through the supersonic turbine 5 passes through the superheater 7 upstream. The refrigerant then emerges compressed from the turbine 5 to emerge in the absorber 4.

At the level of the absorber 4 the refrigerant coming from the turbine 5 and the refrigerant coming from the evaporator 3 are mixed before passing through the loop 11. The refrigerant is absorbed by the absorbent and the rich working solution leaves the absorber 4 to circulate in the loop 11 comprising the economizer 8, the pump 9 and the expansion valve 10 as described above.

The production of cold takes place at the level of the evaporator 3 during the evaporation of the refrigerant fluid which is accompanied by a cooling of the hot source. The cooled hot source can then be used for example for air conditioning. The electricity is produced by the supersonic turbine 5 connected to an electric generator.

The operation of the system for simultaneous production of cold and electricity with the possibility of efficient adjustment of the ratio between these two productions is shown in figure 5 .

The working solution circulation management module initiates circulation of the working solution according to an absorption cycle and a power generation cycle with a ratio between the two. To do this, the module only closes the adjustment valves on the fluidic line branching off from that of the ejector 50 between the generator 1 and the turbine 5: thus all the working fluid necessarily passes through the ejector 50 before leading to the supersonic turbine 5. The function D/ and preferably D0/ (ejector with variable neck section) are thus achieved. The ejector 50 makes it possible to increase the flow rate passing through the cold part of the circuit 100, and therefore the cold power produced, while maintaining good efficiency in the production of electricity by the turbine 5. The function D0/ is ensured by changing the section of the ejector with variable neck section so as to optimize its performance for each operating condition.

We now describe the operation of the system according to the figure 5 to perform these functions D/ and D0/.

At the outlet of the generator 1, the refrigerant of the working solution is directed partially towards the part of the circuit 100 implementing a cold production cycle and partially towards the other part implementing an electricity production cycle. Part of the refrigerant leaving the generator 1 is diverted to the supersonic turbine 5 while the other part circulates to the condenser 2 by crossing the rectifier 13 upstream. The refrigerant leaves the condenser 2 to cross the sub-cooler 6 and the expansion valve 12 before arriving in the evaporator 3. The refrigerant leaves the evaporator 3 to cross the sub-cooler 6.

Part of the refrigerant is then diverted into line 15 and passes through exchanger 14 to heat the fluid which is injected as secondary fluid into ejector 50.

The other part of the refrigerant not bypassed in line 15 arrives in absorber 4.

The refrigerant is absorbed by the absorbent and the rich working solution leaves the absorber 4 to circulate in the loop 11 and therefore successively passes through the pump 9, the economizer 8 before arriving in the generator 1. The lean working solution leaves the generator 1 to pass successively through the economizer 8 and the expansion valve 10 before arriving in the absorber 4.

The part of the refrigerant passing through the supersonic turbine 5 necessarily passes upstream through the ejector 50 which increases the flow rate and then the superheater 7. The refrigerant then comes out compressed from the turbine 5 to emerge in the absorber 4.

At the level of the absorber 4 the refrigerant coming from the turbine 5 and the refrigerant coming from the evaporator 3 are mixed before passing through the loop 11. The refrigerant is absorbed by the absorbent and the rich working solution leaves the absorber 4 to circulate in the loop 11 comprising the economizer 8, the pump 9 and the expansion valve 10 as described above.

The increased cold production compared to the figure 4 takes place at the level of the evaporator 3 during the evaporation of the refrigerant which is accompanied by a cooling of the hot source. The cooled hot source can then be used for example for air conditioning. The electricity is produced by the supersonic turbine 5 connected to an electric generator.

• Générateur 1-Température source chaude : 100°C
• Rectifieur 13-Taux de rectification : 0,495
• Surchauffeur 7-Température à l'entrée de l'expanseur (fonctions B/, C/, D/ et D0/) : 120°C
• Condenseur 2-Température source intermédiaire : 30°C
• Evaporateur 3-Surchauffe : 5°C, Température source froide (fonction A/ et B/) : 5° C, Température source froide (fonction D/ et D0/) : 5 °C
• Absorbeur 4-Température source intermédiaire : 30°C
• Pompe 9-Débit 350 kg/h, Rendement : 80 %
• Compresseur 5/Expanseur-Rendement : 50 %

An example of a typical configuration is provided below with for each component of the system:

• Generator 1-Hot source temperature: 100°C
• Rectifier 13-Rectification rate: 0.495
• Superheater 7-Temperature at the expander inlet (functions B/, C/, D/ and D0/): 120°C
• Condenser 2-Intermediate source temperature: 30°C
• Evaporator 3-Overheating: 5°C, Cold source temperature (function A/ and B/): 5°C, Cold source temperature (function D/ and D0/): 5°C
• Absorber 4-Intermediate source temperature: 30°C
• Pump 9-Flow rate 350 kg/h, Efficiency: 80%
• Compressor 5/Expander-Performance: 50%

Tables 1 and 2 below illustrate the performances that can be achieved with this example of a typical configuration for the operating modes allowing functions A/ to D0 to be performed, case 3 being the comparative one

The performances were calculated using a numerical model developed with the software marketed under the acronym EES (for “Engineering Equation Solver”) in which, for each component, the energy and mass conservation equations are formulated under the assumption of stationarity.

These tables 1 and 2 therefore summarize from different cases 1 to 4, the different powers, COP and efficiencies for functions A/ to D/ with the standard configuration. [Table 1] CASE Temperature cold [°C] Intermediate source temperature [°C] Generator 1 temperature [°C] Pump output [kg/h] Absorber power [kW] Condenser Power [kW] Power Generator 1 [kw] Cooling power [kW] Turbine electrical power [kW] COP [-] Cycle power output Second principle yield 1 5 30 100 350 1599 1086 18.35 10.35 0 0.56 0% 26.84% 2 > 30 100 350 16.87 4.57 18.32 4.35 0.54 0.56 4.9% 26.44% 3 5 30 100 350 169 6.463 18.33 6.159 0.1028 0.56 1.3% 18.83% 4 5 30 100 350 16.8 6.473 18.33 6.169 0.3174 0.56 4% 24.64% CASE High pressure [bar] Low pressure [bar] Turbine inlet pressure [bar] Generator steam flow [kg/h] Cooling circuit refrigerant flow [kg/h] Flow treated turbine [kg/h] Cold Ratio 1 13.43 4.27 13.43 34.33 31.87 0 1 2 1343 421 1343 34.24 13.41 19.8 0.422 3 13.43 4.27 933 34.27 18.96 13.84 0.596 4 13.43 4.27 11.22 34.27 18.99 16.77 0597

• CAS 1 : Seule production de froid à l'évaporateur (fonction A/).
• CAS 2 : Productions simultanées de travail mécanique/électrique par la turbine et de froid à l'évaporateur (fonction C/).
• CAS 3 : Régulation du rapport entre production de froid et production électrique en effectuant une lamination avant l'entrée dans la turbine.
• CAS 4 : Régulation du rapport entre production de froid et production électrique en utilisant l'éjecteur selon l'invention.

In these tables 1 and 2:

• CASE 1: Only cold production at the evaporator (function A/).
• CASE 2: Simultaneous production of mechanical/electrical work by the turbine and cold in the evaporator (function C/).
• CASE 3: Regulation of the ratio between cold production and electrical production by carrying out lamination before entering the turbine.
• CASE 4: Regulation of the ratio between cold production and electrical production using the ejector according to the invention.

où Qchaud est la puissance, Q̇_des délivrée par la source de chaleur au niveau du générateur 1, sous forme de chaleur, Wturb la puissance électrique délivrée par la turbine 5, Wpump la puissance électrique consommée par la pompe 9.For cold production alone and combined with electricity production (functions A/, C/, D/ and D0/), the COP is defined by equation (1).
[Equation 1] $$\mathit{COP}=\frac{\mathit{Qhot}}{\mathit{Wturb}+\mathit{wpump}}$$

where Qchaud is the power, Q̇ _des delivered by the heat source at the level of the generator 1, in the form of heat, Wturb the electric power delivered by the turbine 5, Wpump the electric power consumed by the pump 9.

avec
[Equation 3 ] $${\eta }_{\mathit{II},\mathit{froid}}=\frac{\mathit{COP}}{{\mathit{COP}}_{\mathit{Carnot}}}$$

[Equation 4] $${\mathit{COP}}_{\mathit{Carnot}}=\frac{T_e\times \left(T_g-T_c\right)}{T_g\times \left(T_c-T_e\right)}$$

[Equation 5 ] $$\mathit{COP}=\frac{{\dot{Q}}_{\mathit{Evap}}}{\left({\dot{Q}}_{\mathit{gen}}+{\dot{W}}_{\mathit{pomp}}\right)\times r_s}$$

[Equation 6 ] $${\eta }_{\mathit{II},\mathit{puissance}}=\frac{{\eta }_I}{{\eta }_{\mathit{Carnot}}}$$

[Equation 7 ] $${\eta }_{\mathit{Carnot}}=1-\frac{T_c}{T_g}$$

[Equation 8 ] $${\eta }_I=\frac{{\dot{W}}_{\mathit{turb}}}{\left({\dot{Q}}_{\mathit{gen}}+{\dot{W}}_{\mathit{pomp}}\right)\times r_s+{\dot{Q}}_{\mathit{SH}}}$$

For the production of cold alone and combined with the production of electricity (functions A/, C/, D/ and D0/) the efficiency of the second principle η _II,cycle is defined by equation (2):
[Equation 2] $${\eta }_{\mathit{II},\mathit{cycle}}={\eta }_{\mathit{II},\mathit{cold}}\times r_s+{\eta }_{\mathit{II},\mathit{power}}\times \left(1-r_s\right)$$

with
[Equation 3 ] $${\eta }_{\mathit{II},\mathit{cold}}=\frac{\mathit{COP}}{{\mathit{COP}}_{\mathit{Carnot}}}$$

[Equation 4] $${\mathit{COP}}_{\mathit{Carnot}}=\frac{T_e\times \left(T_g-T_{\mathrm{vs}}\right)}{T_g\times \left(T_{\mathrm{vs}}-T_e\right)}$$

[Equation 5 ] $$\mathit{COP}=\frac{{\dot{Q}}_{\mathit{Evap}}}{\left({\dot{Q}}_{\mathit{people}}+{\dot{W}}_{\mathit{pump}}\right)\times r_s}$$

[Equation 6 ] $${\eta }_{\mathit{II},\mathit{power}}=\frac{{\eta }_I}{{\eta }_{\mathit{Carnot}}}$$

[Equation 7 ] $${\eta }_{\mathit{Carnot}}=1-\frac{T_{\mathrm{vs}}}{T_g}$$

[Equation 8 ] $${\eta }_I=\frac{{\dot{W}}_{\mathit{turb}}}{\left({\dot{Q}}_{\mathit{people}}+{\dot{W}}_{\mathit{pump}}\right)\times r_s+{\dot{Q}}_{\mathit{SH}}}$$

Where r _s is the ratio between the flow passing through the cold part of the circuit and the flow produced by the generator, T _e is the temperature external to the evaporator, T _c the temperature external to the condenser, T _g the temperature external to the generator.

To highlight the contribution made by an ejector 50 according to the invention, the inventors carried out the simulation with a comparative configuration (case 3), similar to that typical of the invention but which comprises instead of an ejector a throttling valve. In this comparative configuration, the ejector 50, the line 15 and the exchanger 14 are therefore eliminated and the rolling valve is arranged on the fluidic line between the generator 1 and the superheater 7, downstream of the bypass of the line towards the condenser 2. Thus, in this comparative configuration (case 3), the ratio between electricity production and cold production is regulated by means of the rolling valve.

By comparing the results of Tables 1 and 2 between case 4 (ejector according to the invention) and case 3 (rolling valve), it can be seen that the implementation of the ejector makes it possible to have almost the same production of cold power and a much greater electrical production than with a rolling valve. This translates into a much higher electrical production efficiency and overall efficiency of the second principle of the cycle in the case of use of the ejector compared to that of a throttling valve.

• augmentation du débit de fluide de travail au travers de la turbine 5 (16,77 kg/h avec éjecteur contre 13,84 kg/h sans éjecteur) ;
• augmentation de la pression à l'amont de la turbine 5 (11,22 bar avec éjecteur contre 9,335 bar sans éjecteur) ;
• augmentation du rendement de la turbine 5 (40% avec éjecteur contre 18,4 % sans éjecteur) ;
• augmentation de la teneur en ammoniac (0,969 avec éjecteur contre 0,963 sans éjecteur).

This higher production is generated by the following increases:

• increase in the flow rate of working fluid through the turbine 5 (16.77 kg/h with ejector against 13.84 kg/h without ejector);
• increase in pressure upstream of turbine 5 (11.22 bar with ejector against 9.335 bar without ejector);
• increase in the efficiency of turbine 5 (40% with ejector against 18.4% without ejector);
• increase in ammonia content (0.969 with ejector against 0.963 without ejector).

Nevertheless, the use of an ejector implies a slight increase in the thermal power necessary for the overheating by the exchanger 14.

The ejector 50 according to the invention is dimensioned at the nominal flow on the turbine 5 for the electrical production (function D/). An example of the arrangement of an ejector 50 upstream of the superheater 7 and the supersonic turbine 5 is shown in figure 6 . For sizing, it is necessary to correctly size the critical section of the sonic neck 51 of the primary fluid injector, which defines the critical flow treated by it, and its outlet section 53 which defines the outlet pressure of the injector and therefore influences the drive ratio.

An example of calculation carried out with the EES software corresponding to the configuration of the figure 6 is detailed in Table 3. [Table 3] Primary injector inlet Secondary injector inlet Primary injector outlet Secondary injector outlet Mixer outlet Diffuser outlet 51 52 53 53 54 55 Section ( ^mm2 ) 1.5 32 5 2.5 7.5 30 Fluid pressure (bar) 13 4 3.7 3.7 9.19 9.71 Fluid temperature (°C) 100 43 25.43 38.2 81.52 85.81

The ejector 50 is in this configuration sized so as to have a critical flow rate of 10 kg/h and a small drive ratio.

The use of a variable section ejector 50 makes it possible to finely and efficiently regulate the electrical production for different speeds (D0/ function).

Other variants and improvements can be envisaged without departing from the scope of the invention.

Instead of a working solution consisting of the ammonia/water couple, it is possible to envisage using ionic liquids in the system according to the invention.

In all the operating modes in which the turbine 5 operates (functions B/, C/ D/ and D0/), the turbine may not be connected to an electric generator and produce mechanical work only.

It is possible to provide for the driving of the pump 9 by the turbine 5 in certain cases.

The flows of the working fluid can be separated at the output of rectifier 13, rather than at the output of generator 1 according to the configuration shown in figure 1 .

For the operation of the rectifier 13, the fluid leaving the pump 9 can be used as a cold source in order to rectify the ammonia.

A bypass fluidic line can be added to increase the pressure of the absorber 4 from the ejector 50.

The system can comprise at least one cold storage module associated with the evaporator 3. The cold storage thus allows energy storage when the source and the need are not concomitant. The stored cold can be removed from storage in the form of cold or in the form of electricity depending on the needs. The cold storage module can be a Phase Change Material thermal storage system or directly a cold fluid storage. The cold storage module is associated with the evaporator 3 to store cold during operation for the production of cold. Advantageously, the cold storage module is also associated with the absorber 4 to destock cold to the absorber 4 when a cooling source is desired, that is to say in particular in the different operating modes.

The system can include a cold storage module associated with the absorber 4 to remove cold storage.

The system can also comprise at least one calorie storage module associated with the absorber 4 or associated with the generator 1 to destock the calories.

The system can comprise at least one electricity storage module associated with the supersonic turbine 5 and more specifically with the electric generator associated with the turbine 5. The electricity storage thus allows energy storage when the source and the need are not concomitant. The stored electricity can be destocked in the form of cold or else in the form of electricity depending on the needs.

By way of example, electric batteries can be provided.

List of cited references

• [1]: Gokmen Demirkaya, Ricardo Vasquez Padilla, Armando Fontalvo, Yee Yan Lim. “Thermal and Exergetic Analysis of the Goswami Cycle Integrated with Mid-Grade Heat Sources”. August 2017 Entropy 19(8):416. DOI: 10.3390/e19080416 .
• [2]: Voeltzel, N., Phan, HT, Blondel, Q., Gonzalez, B., and Tauveron, N., 2020, "Steady and Dynamical Analysis of a Combined Cooling and Power Cycle," Therm. Science. Eng. Prog., 19 (July), p. 100650 .
• [3]: Elbel, S., and Hrnjak, P., 2008, "Experimental Validation of a Prototype Ejector Designed to Reduce Throttling Losses Encountered in Transcritical R744 System Operation," Int. J. Refrig., 31(3), p. 411- 422 .
• [4] Ayou Dereje S. er al: "An overview of combined absorption power and cooling cycles", RENEWABLE AND SUSTAINABLE ENERGY REVIEWS, vol. 21, 1 May 2013 (2013-05-01), pages 728-748, XP055897934, US ISSN: 1364-0321, DOI: 10.1016/j.rser.2012.12.068

Claims (12)

1. System for producing cold and electrical energy, comprising:

   - a desorber, called generator (1),

   - a condenser (2),

   - an evaporator (3),

   - an absorber (4),

   - a fluidic absorption circuit (100) in which a working fluid comprising a refrigerant fluid and an absorbent circulates, the fluidic circuit (100) connecting the generator (1) to the condenser (2), the condenser (2) to the evaporator (3), the evaporator (3) to the absorber (4) and the absorber (4) to the generator (1),

   - a supersonic turbine (5) arranged on the fluidic circuit (100) between the generator (1) and the absorber (4) bypassing the condenser (2) and the evaporator (3), the turbine being configured to operate as an electrical generator in order to produce electricity,

   - at least one ejector (50) arranged on the fluidic circuit between the generator and the turbine.
2. System according to Claim 1, the ejector being a simple ejector or an ejector with variable throat cross section.
3. System according to Claim 1 or 2, the working fluid comprising ammonia (NH₃) as refrigerant fluid and water (H₂O) as absorbent.
4. System according to one of the preceding claims, the fluidic circuit (100) comprising an exchanger (14) arranged on a fluidic bypass line (15) branching off the fluidic connection between the evaporator (3) and the absorber (4), the bypass line (15) being connected to the injector of the secondary fluid of the ejector (50) such that the exchanger (14) heats the secondary fluid prior to its entry into the ejector (50).
5. System according to one of the preceding claims, the turbine (5) being configured to drive the pump (9) for circulating the working fluid.
6. System according to one of the preceding claims, comprising a rectifier (13) for the refrigerant fluid, arranged between the generator (1) and the condenser (2).
7. System according to Claim 6, flows of what are referred to as rich and poor solutions of the working fluid being separated at the outlet of the generator (1) or at the outlet of the rectifier (13).
8. System according to Claim 6 or 7, the fluid at the outlet of the pump (9) for circulating the working fluid being used as cold source of the rectifier (13).
9. System according to one of the preceding claims, comprising a fluidic bypass line between the ejector (50) and the absorber (4) so as to increase the pressure of the working fluid in the latter.
10. System according to one of the preceding claims, comprising a low-temperature heat advantageously between 70°C and 150°C as heat source.
11. Method for producing electrical energy and thermal energy implemented by a system according to any one of the preceding claims, comprising:

    - in a first operating mode for producing cold only, circulating the working fluid in the fluidic circuit (100) successively through the generator (1) the condenser (2), the evaporator (3) then the absorber (4) and then again into the generator (1);

    - in a second operating mode for producing electrical energy only, circulating the working fluid in the fluidic circuit (100) successively through the generator (1), the supersonic turbine (5) associated with an electrical generator, the absorber (4) and then again into the generator (1);

    - in a third operating mode for co-producing cold and electrical energy, circulating one portion of the working fluid in the fluidic circuit (100) successively through the generator (1), the condenser (2), the evaporator (3) then the absorber (4) and then again into the generator (1) and the other portion of the working fluid successively through the generator (1), the supersonic turbine (5) associated with an electrical generator, the absorber (4) and then again into the generator (1);

    - in a fourth operating mode for co-producing cold and electrical energy with a regulated ratio between cold production and electrical production, circulating one portion of the working fluid in the fluidic circuit (100) successively through the generator (1), the condenser (2), the evaporator (3) then the absorber (4) and then again into the generator (1) and the other portion of the working fluid successively through the generator (1), the ejector (50), the supersonic turbine (5) associated with an electrical generator, the absorber (4) and then again into the generator (1).
12. Use of a system for producing cold and electrical energy according to any one of Claims 1 to 10 for an electrical production of a power greater than 100 kWe.

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