Thermodynamic system for storing/producing electrical energy

Abstract

A system for producing and storing electrical energy includes a thermally insulated chamber containing a first circuitry in which circulates a first working fluid, a hot source, a cold source, wherein the hot source is composed of a pure water ice slurry at 0 C., the cold source is composed of an ice slurry with a temperature lower than or equal to 40 C. and the system for producing/storing electrical energy further includes a second circuitry of working fluid for circulating a second working fluid between the hot source and a thermostat, wherein the second working fluid is circulated between said thermostat and the hot source by an auxiliary expansion valve and an auxiliary compressor.

Claims

1. A system for producing and storing electrical energy, said system comprising: a thermally insulated chamber comprising a first circuit including a first working fluid circulating therein; a hot source and a cold source, wherein said hot source and said cold source are thermally insulated from each other; wherein: (i) a first leg of the first circuit passes through the hot source for heat exchange between the first working fluid in the first leg and the hot source; (ii) a second leg of the first circuit passes through the cold source for heat exchange between the first working fluid in the second leg and the cold source; the first circuit further comprising a third leg that extends between and that is connected in series between the first leg and the second leg and a fourth leg that extends between and that is connected in series between the second leg and the first leg such that said first leg is located between said third and fourth legs and such that said second leg is located between said third and fourth leg; the third leg connecting the cold source to the hot source and comprising a pump for circulating the first working fluid in liquid phase; the fourth leg connecting the hot source to the cold source and comprising a turbine for circulating the first working fluid in gas phase; the hot source comprising a pure water ice slurry always at 0 C.; the cold source comprising an ice slurry with a temperature lower than or equal to 40 C.; said system further comprising: a second circuit in which a second working fluid circulates between the hot source and a constant temperature system located outside the thermally insulated chamber, the constant temperature system being selected from the group comprising: ambient air, a water reserve, a water stream, a water course, a waterway; an auxiliary expansion valve and an auxiliary compressor for circulating the second working fluid between said constant temperature system and the hot source for heat exchange from the hot source to the constant temperature system, wherein the system has two operating modes, the turbine and the pump having a reversible operation, wherein in a first operating mode, the turbine operating as a compressor causes the first working fluid to evaporate by heat exchange in the cold source, the first working fluid then condensing by heat exchange in the hot source, before being expanded by the pump operating as an expansion valve, wherein in a second operating mode, the first working fluid evaporates by heat exchange in the hot source, passes through the turbine where the first working fluid is expanded to produce electricity, and condenses by heat exchange in the cold source.

2. The system according to claim 1, wherein the pump is a reversible pump, and wherein the turbine is a reversible turbine.

3. The system according to claim 1, further comprising a low temperature regenerator arranged to enable a heat exchange between the third and fourth legs connected to the cold source.

4. The system according to claim 1, wherein a high temperature regenerator is arranged between portions of the fourth leg entering and exiting the turbine.

5. The system according to claim 1, wherein a superheating member providing an external heat to the first working fluid is provided on the first fluid circuitry immediately upstream of an input of the turbine.

6. The system according to claim 1, wherein a compressor assembly is provided on a fifth circuitry leg in parallel to the fourth leg.

7. The system according to claim 1, wherein an expansion valve assembly is provided on a sixth circuitry leg in parallel to the third leg.

8. The system according to claim 1, wherein the cold source comprises an eutectic mixture of water and calcium chloride.

9. The system according to claim 1, wherein the first circuit and the second circuit are connected together as a single closed circuit, and wherein the first and second working fluids constitute a single working fluid located in the first and second circuits.

10. A system for producing and storing electrical energy, said system comprising: a thermally insulated chamber comprising a first circuit including a first working fluid circulating therein; a hot source and a cold source, wherein said hot source and said cold source are thermally insulated from each other; wherein: (i) a first leg of the first circuit passes through the hot source for heat exchange between the first working fluid in the first leg and the hot source; (ii) a second leg of the first circuit passes through the cold source for heat exchange between the first working fluid in the second leg and the cold source; the first circuit further comprising a third leg that extends between and that is connected in series between the first leg and the second leg and a fourth leg that extends between and that is connected in series between the second leg and the first leg such that said first leg is located between said third and fourth legs and such that said second leg is located between said third and fourth leg; the third leg connecting the cold source to the hot source and comprising a pump for circulating the first working fluid in liquid phase; the fourth leg connecting the hot source to the cold source and comprising a turbine for circulating the first working fluid in gas phase; the hot source comprising a pure water ice slurry always at 0 C.; the cold source comprising an ice slurry with a temperature lower than or equal to 40 C.; said system further comprising: a second circuit in which a second working fluid circulates between the hot source and a constant temperature system located outside the thermally insulated chamber, the constant temperature system being selected from the group comprising: ambient air, a water reserve, a water stream, a water course, a waterway; an auxiliary expansion valve and an auxiliary compressor for circulating the second working fluid between said constant temperature system and the hot source for heat exchange from the hot source to the constant temperature system, wherein: a compressor assembly is provided on a fifth circuitry leg in parallel to the fourth leg; an expansion valve assembly is provided on a sixth circuitry leg in parallel to the third leg; said system further comprising a seventh leg passing through the hot source and an eighth leg passing through the cold source; wherein the fifth leg, sixth leg, seventh leg, and eighth leg form a third closed circuit independent from the first circuit and parallel to the first circuit, said third closed circuit comprising a third working fluid therein.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order to better illustrate the subject-matter of the present invention, an embodiment will now be described hereinafter, for illustrative and not limitative purposes, in conjunction with the accompanying drawings.

(2) In these drawings:

(3) FIG. 1 is a diagram of an electrical energy storage/production system according to a first embodiment of the present invention;

(4) FIG. 2 is a diagram of an electrical energy storage/production system according to a second embodiment of the present invention;

(5) FIG. 3 is a diagram of an electrical energy storage/production system according to a third embodiment of the present invention;

(6) FIG. 4 is a diagram of an electrical energy storage/production system according to a fourth embodiment of the present invention;

(7) FIG. 5 is a diagram of an electrical energy storage/production system according to a fifth embodiment of the present invention; and

(8) FIG. 6 is a diagram of an electrical energy storage/production system according to a sixth embodiment of the present invention.

DETAILED DESCRIPTION

(9) In the following detailed description, the same reference numerals denote the same structural elements.

(10) When referring to FIG. 1, it can be seen that there is shown a system 1 for storing/producing electrical energy according to a first embodiment of the invention.

(11) The system 1 includes a hot source 2, a cold source 3, both thermally insulated (and in particular from one another), a circuit 4 comprising a portion 4a of heat exchange with the hot source 2 and a portion 4b of heat exchange with the cold source 3.

(12) The hot source 2 is made of a pure water ice slurry at 0 C., the cold source 3 being made of an ice slurry at 50 C., comprising an eutectic mixture of water and of calcium chloride.

(13) A reversible turbine 5 is provided on the leg 4c of the circuit 4 connecting the hot source 2 to the cold source 3, and a reversible pump 6 is provided on the other leg 4d of the circuit 4 connecting the cold source 3 to the hot source 2.

(14) The turbine 5 and the pump 6 being reversible, the system 1 can be used to store electrical energy (charge) or to produce electrical energy (discharge).

(15) The system 1 further comprises an element 7, acting as a thermodynamic thermostat, at a temperature generally higher than that of the hot source 2, to exchange heat therewith, via an auxiliary expansion valve 8 and an auxiliary compressor 9.

(16) The element 7 may also be at a temperature lower than or equal to that of the hot source 2, without departing from the scope of the present invention.

(17) The working fluid used in the circuit 4, as well as in the circuit connecting the hot source 2 and the element 7, is a refrigerant fluid, for example R410A or CO.sub.2, without these two examples being limitative.

(18) Although it is not shown to avoid overloading the drawing, the system 1 further comprises a thermally insulated sealed chamber containing the circuit 4, the hot source 2, the cold source 3, the turbine 5, the pump 6. The auxiliary compressor 9 and the auxiliary expansion valve 8 may be inside the chamber but are, preferably, outside, connected thereto in a sealed manner. The element 7 is an exchanger immersed in a substantially constant temperature fluid, for example outside air or water (waterway/waterstream or water body) or another fluid at a temperature higher than that of the hot source 2.

(19) The chamber may for example consist of a sealed container, the chamber comprising means for connecting the system 1 to a local or interconnected electrical grid, so that the system 1 can exchange electric energy with the outside.

(20) The system 1 has two operating modes, the turbine 5 and the pump 6 having a reversible operation.

(21) In a first operating mode (charge or storage), the turbine 5 operating as a compressor causes the working fluid to evaporate in the exchanger immersed in the cold source 3 (causing the formation of crystals in the cold source 3), the working fluid then condensing in the exchanger immersed in the hot source 2 (melting ice crystals in the hot source), before being expanded by the pump 6 operating as an expansion valve.

(22) In a second operating mode (discharge or production), the working fluid evaporates in the exchanger immersed in the hot source 2 (causing the formation of ice crystals in the hot source 2), passes through the turbine 5 where it expands to produce electricity, and condenses in the exchanger immersed in the cold source 3, melting ice crystals in the cold source 3.

(23) Thus, in the system 1 according to the invention, the electricity storage results in the formation of ice in the cold source 3 and the electricity production results in the consumption of ice in the cold source 3, the quantity of ice in the hot source 2 being regulated by heat exchange with the assembly 7.

(24) When referring now to FIG. 2, it can be seen that there is shown a system 100 according to another embodiment. The common elements with the embodiment of FIG. 1 are not described again here, only the elements which differ between the two embodiments being described thereafter.

(25) In this second embodiment, the leg 4c of the first embodiment is divided into two sub-legs 4c1 and 4c2 separated by a high temperature regenerator 11 and legs 4e and 4f are added, respectively in parallel to legs 4c1, 4d of the circuit 4.

(26) In addition, a superheating member 10, positioned upstream of the turbine 5, is used to heat the working fluid prior to its expansion in the turbine 5, in the discharge operating mode of the system 100, in order to increase the efficiency of the system 100. The superheating member 10 heats the working fluid from a waste heat source of diesel engine or generator type (not shown), the temperature of the superheating member 10 being about 160 C. (diesel engine) or 260 C. (gas turbine).

(27) Further, the high temperature regenerator 11 on the leg 4c1 of the circuit 4 and a low temperature regenerator 12 (shown in two separate parts to avoid overloading the reading of the Figure), provided on the legs 4c2 and 4d of the circuit 4, also allow to increase the efficiency of the system 100 by improving the heat exchange of the working fluid.

(28) The three-way valves V1 and V2 allow, as in the system 1, a reversible operation of the system 100 in charge or discharge.

(29) In the charge mode, the working fluid flows in the legs 4e, 4a, 4f, 4b and 4c2, the turbine 5 operating as a compressor, the operation being similar to that described in relation to the first embodiment.

(30) In the discharge mode, the working fluid flows in the leg 4c1, in the high temperature regenerator 11, in the superheating member 10, in the turbine 5, and then through the high temperature regenerator 11 in the leg 4c2, the low temperature regenerator 12, the leg 4b, the pump 6, the low temperature regenerator 12, the legs 4d and 4a, the operation being similar to that described for the first embodiment.

(31) Thus, the working fluid only passes through the superheating member 10 in the discharge operation.

(32) It is understood that in this embodiment, the regenerators 11, 12 improve efficiency, but are optional, and a system similar to the system 100, in which the regenerators 11, 12 are absent also falls within the scope of the present invention.

(33) The low temperature regenerator 12 serves to cool the gas working fluid entering the cold source 3 during the discharge phase, using, in steady state, the cold liquid working fluid leaving the cold source 3 for cooling the gas working fluid entering therein, in order to consume as little ice crystals as possible in the cold source 3.

(34) Referring now to FIG. 3, it can be seen that there is shown a system 200 according to a third embodiment.

(35) This system is similar to the system 1 of FIG. 1, the leg 4c of FIG. 1 being, as with the second embodiment, divided into two sub-legs 4c1 and 4c2 and connected to the turbine 5 by a high temperature regenerator 11.

(36) As with the second embodiment, a superheating member 10 is connected to the turbine 5.

(37) Furthermore, a leg 4g, on which is mounted a compressor 13 is provided in parallel to the legs 4c1 and 4c2 and a leg 4h, on which is mounted an expansion valve 14, is provided in parallel to the leg 4d.

(38) The operation of the system 200 of FIG. 3 is essentially identical to the operation of the system 100 of FIG. 2.

(39) The leg 4g plays the same role as the leg 4e in FIG. 2, the compressor 13 being for recharging the cold source 3 with ice crystals during a charge cycle.

(40) The compressor 13 may be a single compressor but can also be a set of compressors in parallel. The compressor can be in particular driven by a renewable energy source such as a wind turbine (or several wind turbines in parallel) that uses renewable energy (wind) to recharge the cold source 3 without having to take electricity from the grid as in the system 100 of FIG. 2. Thus, the mechanical energy of the wind can be directly transformed into ice without passing through the electric vector, thus avoiding conversion losses.

(41) The leg 4h is then used, with the expansion valve 14, to circulate the working fluid during the charge cycle, onto the legs 4g, 4b, 4h and 4a. However, it is to be noted that this leg 4g carrying the expansion valve 14 may be omitted if the pump 6 is reversible, as in the preceding embodiments.

(42) The discharge operation is the same as in FIG. 2, the working fluid passing through the leg 4c1, the high temperature regenerator 11, the turbine 5, the leg 4c2, the low temperature regenerator 12, the leg 4b, the low temperature regenerator 12, the legs 4d and 4a, and will not be further described here.

(43) FIG. 4 shows a fourth embodiment of a system 300 according to the invention.

(44) The system 300 comprises two legs 4g and 4h, respectively in parallel to the legs 4c1, 4c2 and 4d, and two legs 4i, 4j connecting the legs 4g and 4h in series, the two legs 4i, 4j passing through the hot 2 and cold 3 sources, similarly to the legs 4a and 4b.

(45) Each leg 4g, 4h carries, as in the previous embodiment, a compressor 13, or respectively an expansion valve 14.

(46) There are therefore two parallel circuits, one for the charge cycle (legs 4i, 4g, 4j and 4h), the other for the discharge cycle (4a, 4c1, 4c2, 4b and 4d), the operation being otherwise similar to the one of the previous embodiment and therefore not described again here.

(47) It should be noted that in this embodiment, the pump 6 may be reversible, but is not necessarily reversible. The expansion valve 14 is necessary in this embodiment, unlike the previous embodiment, because in this embodiment, the charge and discharge circuits are independent.

(48) Moreover, the element 7, auxiliary expansion valve 8 and auxiliary compressor 9 circuit was connected for illustrative and not limitative purposes to the circuit 4i, 4g, 4j and 4h in this embodiment as an example, but it is understood that it could also have been connected to the circuit 4a, 4c1, 4c2, 4b and 4d without departing from the scope of the present invention. This element 7, auxiliary expansion valve 8 and auxiliary compressor 9 circuit could also, as in all other embodiments, be a circuit independent from the other circuits, since functionally its role is limited to exchange heat with the hot source 2, without departing from the scope of the present invention.

(49) The fifth embodiment of the system 400 of FIG. 5 is identical to the embodiment 300 of FIG. 3, and the same elements will be not described, only the differences will be described.

(50) The legs 4g and 4h of FIG. 3 are divided in this embodiment of FIG. 5 into sub-legs 4g1, 4g2 and 4h1, 4h2, respectively.

(51) A leg 4k in parallel to the legs 4a and 4b, passes through a source 15 with an intermediate temperature of 21 C. Compressors 13a, 13b on the legs 4g1 and 4g2, and expansion valves 14a, 14b on the legs 4h1 and 4h2, allow working fluid exchanges between the intermediate temperature source 15 and the hot source 2 on the one hand, and the cold source 3 on the other hand.

(52) As for the embodiment of FIG. 3, the compressors 13a, 13b can be a single element or a group of identical elements in parallel.

(53) The intermediate temperature source 15 is made from PCM and allows to optimize the heat exchanges during the charge cycle, the discharge cycle remaining unchanged. In this embodiment, the pump 6 may not be reversible.

(54) FIG. 6 shows a sixth embodiment of a system 500 according to the invention.

(55) The system 500 is a combination of the embodiments of FIGS. 4 and 5, the charge circuit being in parallel to the discharge circuit as in the system 300 of FIG. 4, and the charge circuit having an intermediate temperature source 15 as in the system 400 of FIG. 5.

(56) The operating mode of this system being deduced from the two previous embodiments, it will not be described in more detail here.

(57) In the embodiments of FIGS. 4 and 6, wherein the circuits are in parallel, the working fluid in the two circuits may be identical but two different working fluids may also flow in both circuits, without departing from the scope of the present invention.

(58) The electrical storage capacity of this system is between 11 and 15 kWh/m.sup.3 of ice (depending on the overheating temperature).

(59) For example, with a system according to the invention mounted in a sealed chamber in the form of a container, and with a total volume of ice of 50 m.sup.3 (hot source+cold source), the amount of electrical energy which may be transferred for use is about 500 kWh, or 0.5 MWh.

(60) The chamber in the form of container allows to make the system according to the invention easily transportable and deployable.

(61) Furthermore, its modularity allows to dimension the storage to local needs by adding several elementary bricks (modules).