WO2012168472A2 - Thermoelectric energy storage system with an evaporative ice storage arrangement and method for storing thermoelectric energy - Google Patents

Thermoelectric energy storage system with an evaporative ice storage arrangement and method for storing thermoelectric energy Download PDF

Info

Publication number
WO2012168472A2
WO2012168472A2 PCT/EP2012/060988 EP2012060988W WO2012168472A2 WO 2012168472 A2 WO2012168472 A2 WO 2012168472A2 EP 2012060988 W EP2012060988 W EP 2012060988W WO 2012168472 A2 WO2012168472 A2 WO 2012168472A2
Authority
WO
WIPO (PCT)
Prior art keywords
cold
storage
storage medium
working fluid
thermal storage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2012/060988
Other languages
French (fr)
Other versions
WO2012168472A3 (en
Inventor
Jaroslav Hemrle
Lilian Kaufmann
Mehmet Mercangoez
Andreas Z'graggen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Research Ltd Switzerland
Original Assignee
ABB Research Ltd Switzerland
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ABB Research Ltd Switzerland filed Critical ABB Research Ltd Switzerland
Publication of WO2012168472A2 publication Critical patent/WO2012168472A2/en
Anticipated expiration legal-status Critical
Publication of WO2012168472A3 publication Critical patent/WO2012168472A3/en
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K3/00—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein
    • F01K3/12—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein having two or more accumulators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K11/00—Plants characterised by the engines being structurally combined with boilers or condensers
    • F01K11/04—Plants characterised by the engines being structurally combined with boilers or condensers the boilers or condensers being rotated in use
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
    • F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
    • F01K25/10—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours the vapours being cold, e.g. ammonia, carbon dioxide, ether
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K3/00—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein
    • F01K3/006—Accumulators and steam compressors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K9/00—Plants characterised by condensers arranged or modified to co-operate with the engines
    • F01K9/003—Plants characterised by condensers arranged or modified to co-operate with the engines condenser cooling circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
    • F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • F28F19/006—Preventing deposits of ice
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/14—Thermal energy storage

Definitions

  • the present invention relates generally to thermoelectric energy storage. It relates in particular to a system and method for storing thermal energy on the cold side of a thermoelectric energy storage system using an evaporative ice storage arrangement.
  • ice making methods such as scraped ice production, supercooled ice production and evaporative ice making.
  • a compressor is used to increase the pressure of the resulting water vapor, leading to a super-triple point condensation process.
  • the water vapor is at saturation conditions and therefore the increased saturation pressure also increases the saturation temperature. If the saturation temperature becomes high enough, the vapor can be condensed at above 0°C as liquid water and can easily be removed from the system.
  • Such a super-triple point condensation process may be useful for applications requiring continuous ice production.
  • An alternative ice production method is based on the desublimation of vapor (ice formation) at a condenser surface. Disadvantageously, such ice accumulation on heat exchange surfaces results in a deterioration of the heat transfer.
  • thermoelectric energy storage An example of an industrial application in which a cold storage feature may be used, is a transcritical thermoelectric energy storage (TEES) system, as described by the applicant in an earlier patent application EP 2157317.
  • TEES transcritical thermoelectric energy storage
  • Such a TEES system converts excess electricity to heat in a charging cycle, stores the heat, and converts the heat back to electricity in a discharging cycle, when required.
  • Such an energy storage system is robust, compact, site independent and is suited to the storage of electrical energy in large amounts.
  • Thermal energy can be stored in the form of sensible heat via a change in temperature or in the form of latent heat via a change of phase or a combination of both.
  • the round-trip efficiency of an electrical energy storage system can be defined as the percentage of electrical energy that can be discharged from the storage in comparison to the electrical energy used to charge the storage, provided that the state of the energy storage system after discharging returns to its initial condition before charging of the storage.
  • the efficiency of thermoelectric energy storage is limited for various reasons rooted in the second law of thermodynamics. Firstly, the conversion of heat to mechanical work in a heat engine is limited to the Carnot efficiency. Secondly, the coefficient of performance of any heat pump declines with increased difference between input and output temperature levels. Thirdly, any heat flow from a working fluid to a thermal storage and vice versa requires a temperature difference in order to happen. This fact inevitably degrades the temperature level and thus the capability of the heat to do work.
  • thermodynamic irreversibility factor is the transfer of heat over large temperature differences.
  • a relatively large maximum temperature difference between the thermal storage medium and the working fluid reduces the roundtrip efficiency.
  • relatively large heat exchangers could be constructed or phase change materials can be used for thermal storage.
  • the temperature difference between the thermal storage medium and the working fluid may be reduced using intermediate thermal storage tanks as described in the applicant's earlier patent application EP 2275649.
  • an efficient latent heat storage system such as an ice production and storage system which may be used, inter alia, in combination with the cold side of a TEES system to minimize the maximum temperature difference.
  • the ice production and storage system preferably having relatively small temperature approaches, low parasitic losses and convenient scalability. Such factors would also enable the TEES system to have a higher round-trip efficiency.
  • thermoelectric energy storage system for converting electrical energy into thermal energy to be stored and converted back to electrical energy with an improved round-trip efficiency.
  • This objective is achieved by a thermoelectric energy storage system having an evaporative ice storage arrangement according to claim 1 and a method according to claim 13. Preferred embodiments are evident from the dependent claims.
  • thermoelectric energy storage system comprises a hot thermal storage arrangement comprising one or more hot storage heat exchangers (18); a cold thermal storage arrangement comprising one or more cold storage heat exchangers (14, 36, 40); a thermodynamic cycle unit comprising at least one working fluid circuit for circulating one or more working fluids through at least one hot storage heat exchanger (18) as well as through at least one cold storage heat exchanger (14, 36, 40), each working fluid circuit further comprising at least one compressor or pump (16, 32) for compressing the at least one working fluid, at least one expander (12, 34), preferably a turbine or an expansion valve, for expanding the at least one working fluid, the thermodynamic cycle unit configured to transfer thermal energy from the cold storage unit to the hot storage unit in a charging mode, convert thermal energy from the hot storage unit into mechanical and subsequently electric energy in a discharging mode, wherein the cold storage arrangement comprises a cold thermal storage medium; a vacuum evaporation chamber (28) adapted to evaporate liquid phase cold thermal storage medium to obtain solid phase cold thermal storage medium and gas
  • thermoelectric energy storage system comprising a hot thermal storage arrangement, a cold thermal storage arrangement, a thermodynamic cycle unit comprising at least one working fluid circuit for circulating one or more working fluids through the hot thermal storage arrangement as well as through the cold thermal storage arrangement, each working fluid circuit further comprising at least one compressor or pump (16, 32) for compressing the working fluid, at least one expander (12, 34), preferably a turbine or an expansion valve, for expanding the working fluid, comprises the steps of (a) transferring, by means of the thermodynamic cycle unit, thermal energy from the cold storage arrangement to the hot storage arrangement in a charging mode, (b) converting, by means of the thermodynamic cycle unit, thermal energy from the hot storage arrangement into mechanical and subsequently electric energy in a discharging mode, wherein in the charging mode (c) a liquid cold thermal storage medium is evaporated in a vacuum evaporation chamber (28) to obtain solid phase cold thermal storage medium and gaseous phase cold thermal storage medium, (
  • thermoelectric energy storage system which has a charging cycle for providing thermal energy to a hot thermal storage arrangement and an evaporative ice storage arrangement, and a discharging cycle for generating electricity by retrieving the thermal energy from the hot thermal storage arrangement and the evaporative ice storage arrangement.
  • the thermoelectric energy storage system comprises a working fluid circuit adapted to circulate a working fluid through the hot thermal storage arrangement and the evaporative ice storage arrangement.
  • the evaporative ice storage arrangement comprises a heat exchanger coupled to an cold slurry storage tank via a cold thermal storage medium circuit, wherein in the charging cycle system, the heat exchanger is adapted to function as a desublimation evaporator, and an evaporation chamber is coupled between said desublimation evaporator and the cold slurry storage tank in the cold thermal storage medium circuit.
  • the heat exchanger is adapted to function as a condenser, and the cold slurry storage tank is connected to said condenser via the cold thermal storage medium circuit.
  • the evaporative ice storage arrangement of the present invention is also descriptively referred to herein as sub-triple-point evaporation arrangement.
  • a further heat exchanger positioned in the cold thermal storage medium circuit at the outlet of said condenser and an inlet of the cold slurry storage tank in the discharging cycle system.
  • the heat exchanger and the cold slurry storage tank are directly coupled together in both the charging cycle system and the discharging cycle system.
  • the cold thermal storage medium may be water or a mixture of water and at least one further component.
  • the vacuum evaporation chamber comprises a spraying device adapted to spray the cold thermal storage medium into the chamber where triple point conditions are maintained.
  • a disadvantage associated with known ice production through desublimation of vapor at a condenser surface is that ice accumulation on heat exchange surfaces results in a deterioration of the heat transfer coefficient.
  • the present invention overcomes this problem.
  • the heat exchanger comprises a housing containing cooling conduits and the evaporative ice storage arrangement includes a periodically activated means to defrost ice from the conduits in the heat exchanger in the charging cycle system.
  • a method for storing and retrieving electrical energy in a thermoelectric energy storage system having a hot side and a cold side.
  • the method comprising charging the system by transferring thermal energy to a hot thermal storage medium on the hot side and to a cold thermal storage medium on the cold side, and discharging the system by retrieving thermal energy from the hot thermal storage medium and the cold thermal storage medium and transforming the thermal energy into electrical energy via mechanical energy.
  • the step of transferring thermal energy to the cold thermal storage medium comprises forming ice through desublimation evaporation in an evaporative ice storage arrangement.
  • the step of retrieving thermal energy from the cold thermal storage medium comprises melting the ice through condensation in the evaporative ice storage arrangement.
  • exchanging latent heat with ice allows for relatively compact cold storage and relatively small mass flows when compared with sensible-heat water storages.
  • the footprint of the TEES system is reduced when connected to the evaporative ice storage of the present invention.
  • the step of forming ice through desublimation evaporation in an evaporative ice storage arrangement includes periodically defrosting ice from the conduits in the heat exchanger.
  • the working fluid is preferably carbon dioxide (C0 2 ), or may comprise ammonia (NH 3 ) and/or an organic fluid (such as methane, propane or butane) and/or a refrigerant fluid (such as R 134a (1 ,1 ,1 ,2-Tetrafluoroethane), R245 fa (1 ,1 ,1 ,3,3-Pentafluoropropane)).
  • NH 3 ammonia
  • an organic fluid such as methane, propane or butane
  • a refrigerant fluid such as R 134a (1 ,1 ,1 ,2-Tetrafluoroethane
  • R245 fa (1 ,1 ,1 ,3,3-Pentafluoropropane
  • the evaporative ice storage technology of the present invention can be used in various commercial applications for energy efficiency improvements and load leveling, especially for processes with periodical switching between ice production and ice melting.
  • Examples include air conditioning and district cooling as well as gas turbine air inlet cooling, in which ice could be generated during nighttime and consumed during daytime. It is also envisaged that other applications without such periodical switching could also benefit from the present invention; for example, in food processing applications or in mine cooling.
  • FIG. 1 shows a simplified schematic diagram of a charging cycle of a thermoelectric energy storage system of the present invention having an evaporative ice storage arrangement
  • Figure 2a shows a simplified schematic diagram of a discharging cycle of a thermoelectric energy storage system of the present invention having an evaporative ice storage arrangement
  • Figure 2b shows a simplified schematic diagram of an alternative embodiment of a discharging cycle of a thermoelectric energy storage system of the present invention having an evaporative ice storage arrangement
  • Figure 3 shows an ideal entropy-temperature diagram of the cycles in a transcritical TEES system
  • Figure 4 shows an entropy-temperature diagram of the cycles in a transcritical TEES system using real mechanical components (turbo machines) and the evaporative ice storage arrangement of the present invention with very small approach temperatures between I and II.
  • FIGs 1 and 2 schematically depict a charging cycle system and a discharging cycle system, respectively, of a sub-triple-point evaporation arrangement in accordance with an embodiment of the present invention, when connected to a TEES system.
  • the charging cycle system 10 shown in Figure 1 comprises a working fluid circuit of a work recovering expander 12, an evaporator 14, a compressor 16 and a heat exchanger 18.
  • a working fluid circulates through these components as indicated by the solid line with arrows in Figure 1 .
  • the system further comprises a cold-fluid storage tank 20 and a hot- fluid storage tank 22 containing a fluid thermal storage medium, coupled together via the heat exchanger 18.
  • the thermal storage medium flows between these components as indicated by the dashed line with arrows in Figure 1 .
  • the system includes a sub-triple- point evaporation arrangement 24 comprising an ice slurry storage tank 26 and a vacuum evaporator chamber 28 and the evaporator 14.
  • Water in various states, circulates through the components of the sub-triple-point evaporation arrangement 24.
  • the circulation of the water is indicated by the dotted line with arrows in Figure 1 (although the direct connection between the evaporator 14 and the ice slurry storage tank 26 is an optional feature).
  • the charging cycle system 10 performs a transcritical cycle and the working fluid flows around the TEES system in the following manner.
  • the working fluid in the evaporator 14 absorbs heat from the sub-triple-point evaporation arrangement 24 and evaporates.
  • the vaporized working fluid is circulated to the compressor 16 and surplus electrical energy is utilized to compress and heat the working fluid to a supercritical state. (In such a supercritical state, the fluid is above the critical temperature and critical pressure.)
  • the working fluid is fed through the heat exchanger 18 where the working fluid discards heat energy into the thermal storage medium. It is noted that in the heat exchanger 18 the working fluid pressure will be above the critical pressure, however the working fluid temperature may go below the critical temperature.
  • a transcritical cycle is defined as a thermodynamic cycle where the working fluid goes through both subcritical and supercritical states. There is no distinction between a gas phase and a vapor phase beyond the supercritical pressure and therefore there is no evaporation or boiling (in the regular meaning) in the transcritical cycle.
  • the compressed working fluid exits the heat exchanger 18 and enters the work recovering expander 12.
  • the working fluid is expanded to the lower pressure of the evaporator 14.
  • the working fluid flows from the expander 12 back into the evaporator 14.
  • the thermal storage medium is pumped from the cold-fluid storage tank 20 through the heat exchanger 18 to the hot-fluid storage tank 22.
  • the heat energy discarded from the working fluid into the thermal storage medium is stored in the form of sensible heat.
  • the sub-triple-point evaporation arrangement 24 functions in the following manner during the charging cycle.
  • Water in liquid form is sprayed into the vacuum evaporation chamber 28 to significantly enhance the evaporation surface.
  • Triple point conditions are at least approximately maintained in the chamber and so part of the water droplets evaporate and consequently another part of the water droplets freeze to form ice in the evaporation chamber 28 as ice/water slurry (the ratio of water mass evaporated to frozen water is approximately 1 to 7.).
  • the ice produced in the vacuum evaporation chamber 28 is pumped to the ice slurry storage tank 26 (also referred to herein as the cold slurry storage tank).
  • the water vapor produced in the vacuum evaporation chamber 28 flows into the evaporator 14 and deposits (or "desublimates") on the evaporator surfaces as ice.
  • conditions maintained in the vacuum evaporation chamber 28 preferably correspond at least approximately to triple point conditions of water, which in the present embodiment serves as cold thermal storage medium.
  • a temperature and/or pressure is maintained at values between 10% below and/or 5% above of the corresponding triple point values, preferably at values between 3% below and/or 1 % above, and most preferably at values between 1 % below and or 0.2% above.
  • the evaporator comprises a housing containing cooling conduits.
  • the water vapor in the evaporator 14 is deposited on the surface of the cooling conduits, forming a layer of ice.
  • the character of the deposited ice can range from layer of solid ice through to mushy ice, dependent upon factors such as the material of the conduits, the supercooling of the wall, and so forth.
  • the dimensions of the evaporator 14 are adapted to allow optimal removal of the heat from the sub-triple-point evaporation arrangement by evaporation of the working fluid passing through or flowing around the cooling conduits.
  • the discharging cycle system 30 shown in Figure 2a comprises a working fluid circuit of a pump 32, a heat exchanger 18, a turbine 34, and a condenser 36.
  • a working fluid circulates through these components as indicated by the solid line with arrows in Figure 2a.
  • the system further comprises a cold-fluid storage tank 20 and a hot-fluid storage tank 22 containing a fluid thermal storage medium coupled together via the heat exchanger 18.
  • the thermal storage medium flows between these components as indicated by the dashed line with arrows in Figure 2a.
  • the system also includes a sub-triple-point evaporation arrangement 24 comprising an ice slurry storage tank 26, a slurry heat exchanger 40 and the condenser 36.
  • Water in various states, circulates through the components of the sub-triple-point evaporation arrangement 24 and through the condenser 36.
  • the circulation of the water is indicated by the dotted line with arrows in Figure 2a.
  • the discharging cycle system also performs a transcritical cycle and the working fluid flows around the TEES system in the following manner. Heat energy is transferred from the thermal storage medium to the working fluid causing the working fluid to go through transcritical heating. The working fluid then exits the heat exchanger 18 in a supercritical state and enters the turbine 34 where the working fluid is expanded thereby causing the turbine 34 to generate electrical energy.
  • the working fluid passes through the condenser 36 and subsequently the slurry heat exchanger 40, where the working fluid is condensed by exchanging heat energy with the sub-triple-point evaporation arrangement 24.
  • the condensed working fluid exits the sub-triple-point evaporation arrangement 24 via an outlet and is pumped again beyond its critical pressure into the heat exchanger 18 via the pump 32.
  • the sub-triple-point evaporation arrangement 24 functions in the following manner. Initially, the working fluid in gas phase enters the condenser 36 and increases the temperature in the condenser 36 as it condenses.
  • Both the ice slurry and the working fluid after exiting the condenser 36 may be subsequently circulated through the slurry heat exchanger 40 where the temperature of the working fluid is reduced thereby condensing the remaining working fluid vapor and consequently ice in the slurry is subsequently melted.
  • Figure 2b illustrates an alternative discharging cycle system which similarly comprises a working fluid circuit of a pump 32, a heat exchanger 18, a turbine 34 and a condenser 36.
  • a separate slurry heat exchanger is not required, as the function of the slurry heat exchanger is performed by directing the water circuit through the condenser.
  • the further features of this alternative discharging cycle system are identical to those described in respect of Figure 2a.
  • the solid-line quadrangle shown in the entropy-temperature diagram of Figure 3 represents both the ideal charging and ideal discharging cycles of a standard transcritical TEES system in which on the cold side latent heat is exchanged with the surroundings at ambient temperature.
  • the charging cycle as illustrated, follows a counterclockwise direction and the transcritical discharging cycle follows a clockwise direction.
  • the working fluid is assumed to be carbon dioxide for this exemplary embodiment.
  • latent heat exchange at constant temperature with increasing entropy between point I and point II can clearly be seen and also isentropic compression and expansion with increasing temperature between point II and point III can be seen for charging and discharging, respectively.
  • the entropy of the working fluid falls from 1.70 KJ/kg-K to 1.20 KJ/kg-K during the transcritical cooling by sensible heat exchange between point III, at 120°C, and point IV, at 42°C, in the charging cycle.
  • the transition between point IV and point I occurs with a change in temperature and isentropic compression and expansion for discharging and charging, respectively.
  • FIG 4 shows an entropy-temperature diagram of the charging and discharging cycles in a transcritical TEES system using the sub-triple-point evaporation arrangement 24 of the present invention.
  • the charging cycle is indicated by a dotted line and follows a counterclockwise direction and the discharging cycle is indicated by a solid line and follows a clockwise direction.
  • the working fluid is assumed to be carbon dioxide for this exemplary embodiment. Latent heat exchange at constant temperature with increasing entropy between point I and point II can clearly be seen.
  • heat is transferred from the cold storage fluid at 0°C to the working fluid at -°2 C.
  • discharging heat is transferred from the working fluid at 1 °C to the cold storage fluid at 0°C.
  • Point I and point II in Figure 4 can be equated with the working fluid passing through the evaporator 14 in Figure 1 and the condenser 36 in Figures 2a and 2b.
  • Point IV in Figure 4 can be equated with the working fluid passing through section A of the working fluid circuit in Figures 1 , 2a and 2b.
  • the heat transfer on the cold side heat exchanger is isothermal.
  • the sub-triple-point evaporation arrangement can be run at small approach temperatures due to latent heat exchange with ice on the cold side of the TEES and thus the sub-triple-point evaporation arrangement of the present invention has greater efficiency than a system exchanging sensible heat on the cold side, e.g. with a cold river.
  • the relative size of the evaporator component 14 in the charging cycle system is an important factor in the efficient functioning of the sub-triple-point evaporation arrangement.
  • the surface area of the cooling conduits in the desublimation evaporator 14 are sized so that it balances well the power duty requirement, allowing enough surface area to limit the ice thickness.
  • the deposition heat transfer conditions of the evaporator 14 are such that the thermal resistance is dominated typically by the ice layer depositing on the condenser tube surface. Thus, the deposition heat transfer is mitigated where the layer becomes thicker than about 3 mm, although the evaporator component performance is still acceptable even where the ice layer thickness is 10 mm.
  • an ice layer of 7.5mm thickness may be built up after 8 hours charging cycle.
  • the spraying of water in the vacuum evaporation chamber 28 can be used to control the conditions in such a way that continuous duty is achieved during the whole charging cycle. For example, at the beginning of a charging cycle, when there is little or no ice deposition built up on the cooling conduits, the mass flow of water sprayed in the vacuum evaporation chamber 28 can be at a relatively lower level and then gradually increased to maintain a constant overall heat transfer coefficient of the whole charging cycle as the ice build-up gradually reduces the heat transfer.
  • the arrangement 24 can be adapted such that a relatively small quantity of a dilute solution of highly water soluble inorganic salts is sprayed in the evaporator 14 over the cooling conduits.
  • the resulting ice morphology is softer and more powdery in nature.
  • Such ice may drop from the cooling conduits under its own weight down to the base of the evaporator housing where an outlet pipe may be located or such ice may be periodically "washed down" from the cooling conduits using pressure washer ports.
  • additional warmer working fluid is periodically injected into the cooling conduits in the evaporator 14 during charging which causes the ice built up to melt.
  • additional warmer working fluid is periodically injected into the cooling conduits in the evaporator 14 during charging which causes the ice built up to melt.
  • defrosting may only be required every 2 or 3 hours.
  • several evaporator modules connected in parallel to the evaporation chamber can be used to ensure continuous operation of the charging cycle because even as the ice is melted in one of the evaporator modules, ice production is ongoing in the other modules.
  • the evaporator dimensions can be smaller than those of the main embodiment described herein.
  • the water sprayed into the vacuum evaporator chamber 28 of the sub-triple-point evaporation arrangement may be a mixture of water with another liquid such as ethanol or glycol.
  • another liquid such as ethanol or glycol.
  • triple point conditions of a predominant component in the mixture are at least approximately maintained in the vacuum chamber as detailed above.
  • the heat exchanger 18, cold-fluid storage 20, hot-fluid storage 22 and thermal storage medium of the TEES system are preferably common to both cycles.
  • the desublimation evaporator 14 and the condenser 36 in the sub-triple-point evaporation arrangement 24 may be the same apparatus operated in opposing directions for the charging and discharging cycles respectively.
  • the turbine 34 and the compressor 16 roles as well as the pump 32 / expander 12 roles may be carried out by the same machinery, capable of achieving both tasks.
  • the charging and discharging cycles may be performed consecutively, not simultaneously.
  • a pipe may be connected directly between the evaporator 14 and the ice slurry storage tank 26 during a charging cycle. Parts of the ice building up on the evaporator which are spontaneously released or actively removed may be moved to the ice slurry storage tank 26 via said pipe.
  • the temperature difference between the thermal storage medium and the working fluid may be reduced using intermediate storage tanks as described in the applicant's earlier patent application EP09163084 and thereby increasing the system efficiency.
  • the heat exchanger is a counterflow heat exchanger, and the working fluid of the cycle is preferably carbon dioxide.
  • the thermal storage medium is a fluid, and is preferably water.
  • the compressor 16 is an electrically powered compressor.
  • the counterflow heat exchanger may have a minimal approach temperature, ATmin, of 3 K (ie. the minimal temperature difference between the two fluids exchanging heat is 3 K).
  • ATmin the minimal temperature difference between the two fluids exchanging heat is 3 K.
  • the approach temperature should be as small as possible.
  • the evaporator 14 is a vertically oriented desublimation evaporator of the "shell and tube” type, having working fluid circulating inside of the "tubes” (referred to as conduits herein), and the water vapor on the "shell” side.
  • the surface of the cooling conduits can be increased by utilizing cross sections other than circular, or by the addition of fins. The fins improve the deposition heat transfer by the increasing surface, but also by reducing the thickness of the deposited ice which builds up over a larger surface.
  • the preferred working fluid for circulating in the TEES system is carbon dioxide; mainly due to the higher efficiencies in heat transfer processes and the amiable properties of carbon dioxide as a natural working fluid i.e. non-flammable, no ozone depletion potential, no health hazards etc.
  • the thermal storage medium in the hot side of the TEES system is generally water (if necessary, in a pressurized container), other materials, such as oil or molten salt, may also be used.
  • thermoelectric energy storage system having a charging cycle (10) for providing thermal energy to a hot thermal storage arrangement (18, 20, 22) and an evaporative ice storage arrangement (24), and a discharging cycle (30) for generating electricity by retrieving the thermal energy from the hot thermal storage arrangement (18, 20, 22) and the evaporative ice storage arrangement (24),
  • the thermoelectric energy storage system comprising; a working fluid circuit adapted to circulate a working fluid through the hot thermal storage arrangement (18, 20, 22) and the evaporative ice storage arrangement (24), characterized in that;
  • the evaporative ice storage arrangement (24) comprises a heat exchanger (14, 36) coupled to an cold slurry storage tank (26) via a cold thermal storage medium circuit, wherein in the charging cycle system (10), the heat exchanger is adapted to function as a desublimation evaporator (14), and an evaporation chamber (28) is coupled between said desublimation evaporator (14) and the cold slurry storage tank (26) in the cold thermal storage medium circuit
  • the evaporation chamber (28) comprises a spraying device adapted to spray the cold thermal storage medium into the evaporation chamber (28) where triple point conditions are maintained.
  • thermo storage medium is a mixture of water and at least one further component.
  • thermoelectric energy storage system having a hot side and a cold side, comprising;
  • step of transferring thermal energy to the cold thermal storage medium comprises;
  • step of retrieving thermal energy from the cold thermal storage medium comprises;
  • step of forming ice through desublimation evaporation in an evaporative ice storage arrangement (24) includes periodically defrosting ice from the conduits in the heat exchanger (14).
  • the present invention has the following advantages; minimal system irreversibilities through gentle heat transfer due to relatively small temperature approaches, low parasitic losses as no large fans or compressors are required, and good scalability as the size of the heat exchanger on the cold side of the cycle may be decoupled from the size of the cold storage.
  • sub-triple point evaporative ice storage technology of the present invention can be used in various commercial applications where energy efficiency improvements and load leveling are sought. Examples include air conditioning and district cooling, gas turbine air inlet cooling, food processing, or mine cooling. This list of examples is not exhaustive. While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Other Air-Conditioning Systems (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)

Abstract

A system and method for thermoelectric energy storage is described. The system has a charging cycle (10)for providing thermal energy to a hot thermal storage arrangement (18, 20, 22) and an evaporative ice storage arrangement(24) and a discharging cycle (30) for generating electricity by retrieving the thermal energy. The evaporative ice storage arrangement (24) comprises a heat exchanger(14, 36), an ice slurry storage tank (26), a vacuum evaporation chamber (28) and a slurry heat exchanger(40). The evaporative ice storage arrangement(24) of the present invention functions as a dedicated cold storage for the thermoelectric energy storage system. The cold storage is realized by producing an ice-water mixture during charging of the storage, and using the stored ice-water mixture to condense the working fluid during the discharge cycle (30). Use of this sub-triple-point evaporation arrangement functions to increase the round-trip efficiency of the TEES system through minimising the maximum temperature difference between the working fluid and the thermal storage medium during operating cycles.

Description

THERMOELECTRIC ENERGY STORAGE SYSTEM WITH AN
EVAPORATIVE ICE STORAGE ARRANGEMENT AND METHOD FOR STORING
THERMOELECTRIC ENERGY
FIELD OF THE INVENTION
The present invention relates generally to thermoelectric energy storage. It relates in particular to a system and method for storing thermal energy on the cold side of a thermoelectric energy storage system using an evaporative ice storage arrangement.
BACKGROUND OF THE INVENTION
Storage systems for cold or ice are valuable in many industries and applications. Various ice making methods are known, such as scraped ice production, supercooled ice production and evaporative ice making. In evaporative ice making systems, a compressor is used to increase the pressure of the resulting water vapor, leading to a super-triple point condensation process. The water vapor is at saturation conditions and therefore the increased saturation pressure also increases the saturation temperature. If the saturation temperature becomes high enough, the vapor can be condensed at above 0°C as liquid water and can easily be removed from the system. Such a super-triple point condensation process may be useful for applications requiring continuous ice production. However, known super-triple point evaporation systems are not suitable for certain industrial applications because the size of the compressor limits the capacity of the evaporative ice making system to approximately 3 to 5 MW thermal duty. Such thermal duty is too small for many commercially-viable, industrial applications.
An alternative ice production method is based on the desublimation of vapor (ice formation) at a condenser surface. Disadvantageously, such ice accumulation on heat exchange surfaces results in a deterioration of the heat transfer.
An example of an industrial application in which a cold storage feature may be used, is a transcritical thermoelectric energy storage (TEES) system, as described by the applicant in an earlier patent application EP 2157317. Such a TEES system converts excess electricity to heat in a charging cycle, stores the heat, and converts the heat back to electricity in a discharging cycle, when required. Such an energy storage system is robust, compact, site independent and is suited to the storage of electrical energy in large amounts. Thermal energy can be stored in the form of sensible heat via a change in temperature or in the form of latent heat via a change of phase or a combination of both.
The round-trip efficiency of an electrical energy storage system can be defined as the percentage of electrical energy that can be discharged from the storage in comparison to the electrical energy used to charge the storage, provided that the state of the energy storage system after discharging returns to its initial condition before charging of the storage. The efficiency of thermoelectric energy storage is limited for various reasons rooted in the second law of thermodynamics. Firstly, the conversion of heat to mechanical work in a heat engine is limited to the Carnot efficiency. Secondly, the coefficient of performance of any heat pump declines with increased difference between input and output temperature levels. Thirdly, any heat flow from a working fluid to a thermal storage and vice versa requires a temperature difference in order to happen. This fact inevitably degrades the temperature level and thus the capability of the heat to do work.
It is established that a thermodynamic irreversibility factor is the transfer of heat over large temperature differences. A relatively large maximum temperature difference between the thermal storage medium and the working fluid (whether charging or discharging) reduces the roundtrip efficiency. In order to minimize this maximum temperature difference, relatively large heat exchangers could be constructed or phase change materials can be used for thermal storage. Problematically, these solutions result in a high capital cost and therefore are not generally practical.
On the hot side of a TEES cycle, the temperature difference between the thermal storage medium and the working fluid may be reduced using intermediate thermal storage tanks as described in the applicant's earlier patent application EP 2275649. Thus, there is a need to provide an efficient latent heat storage system such as an ice production and storage system which may be used, inter alia, in combination with the cold side of a TEES system to minimize the maximum temperature difference. The ice production and storage system preferably having relatively small temperature approaches, low parasitic losses and convenient scalability. Such factors would also enable the TEES system to have a higher round-trip efficiency. DESCRIPTION OF THE INVENTION
It is an objective of the invention to provide a thermoelectric energy storage system for converting electrical energy into thermal energy to be stored and converted back to electrical energy with an improved round-trip efficiency. This objective is achieved by a thermoelectric energy storage system having an evaporative ice storage arrangement according to claim 1 and a method according to claim 13. Preferred embodiments are evident from the dependent claims.
A thermoelectric energy storage system according to the invention comprises a hot thermal storage arrangement comprising one or more hot storage heat exchangers (18); a cold thermal storage arrangement comprising one or more cold storage heat exchangers (14, 36, 40); a thermodynamic cycle unit comprising at least one working fluid circuit for circulating one or more working fluids through at least one hot storage heat exchanger (18) as well as through at least one cold storage heat exchanger (14, 36, 40), each working fluid circuit further comprising at least one compressor or pump (16, 32) for compressing the at least one working fluid, at least one expander (12, 34), preferably a turbine or an expansion valve, for expanding the at least one working fluid, the thermodynamic cycle unit configured to transfer thermal energy from the cold storage unit to the hot storage unit in a charging mode, convert thermal energy from the hot storage unit into mechanical and subsequently electric energy in a discharging mode, wherein the cold storage arrangement comprises a cold thermal storage medium; a vacuum evaporation chamber (28) adapted to evaporate liquid phase cold thermal storage medium to obtain solid phase cold thermal storage medium and gaseous phase cold thermal storage medium; a first fluid connection for supplying gaseous phase cold thermal storage medium from said vacuum evaporation chamber (28) to at least one cold storage heat exchanger for evaporating working fluid through desublimation of cold thermal storage medium during the charging cycle; a second fluid connection for connecting said vacuum evaporation chamber to a cold slurry storage tank for storing a mixture of solid phase cold thermal storage medium and liquid phase cold thermal storage medium during the charging cycle; and a third fluid connection for connecting said cold slurry storage tank to at least one cold storage heat exchanger for cooling or condensing working fluid during the discharge cycle. A method in accordance with the present invention for storing energy in a thermoelectric energy storage system, said thermoelectric energy storage system comprising a hot thermal storage arrangement, a cold thermal storage arrangement, a thermodynamic cycle unit comprising at least one working fluid circuit for circulating one or more working fluids through the hot thermal storage arrangement as well as through the cold thermal storage arrangement, each working fluid circuit further comprising at least one compressor or pump (16, 32) for compressing the working fluid, at least one expander (12, 34), preferably a turbine or an expansion valve, for expanding the working fluid, comprises the steps of (a) transferring, by means of the thermodynamic cycle unit, thermal energy from the cold storage arrangement to the hot storage arrangement in a charging mode, (b) converting, by means of the thermodynamic cycle unit, thermal energy from the hot storage arrangement into mechanical and subsequently electric energy in a discharging mode, wherein in the charging mode (c) a liquid cold thermal storage medium is evaporated in a vacuum evaporation chamber (28) to obtain solid phase cold thermal storage medium and gaseous phase cold thermal storage medium, (d) gaseous phase cold thermal storage medium from said vacuum evaporation chamber (28) is desublimated in the cold thermal storage unit in order to evaporate at least one working fluid, (e) a mixture of solid phase cold thermal storage medium and liquid phase cold thermal storage medium is stored in a cold slurry tank (26); and in the discharging mode (e) solid phase cold thermal storage medium from the cold slurry tank (26) is used to cool or condense at least one working fluid.
According to a further aspect of the invention, a thermoelectric energy storage system is provided which has a charging cycle for providing thermal energy to a hot thermal storage arrangement and an evaporative ice storage arrangement, and a discharging cycle for generating electricity by retrieving the thermal energy from the hot thermal storage arrangement and the evaporative ice storage arrangement. The thermoelectric energy storage system comprises a working fluid circuit adapted to circulate a working fluid through the hot thermal storage arrangement and the evaporative ice storage arrangement. The evaporative ice storage arrangement comprises a heat exchanger coupled to an cold slurry storage tank via a cold thermal storage medium circuit, wherein in the charging cycle system, the heat exchanger is adapted to function as a desublimation evaporator, and an evaporation chamber is coupled between said desublimation evaporator and the cold slurry storage tank in the cold thermal storage medium circuit. In the discharging cycle system, the heat exchanger is adapted to function as a condenser, and the cold slurry storage tank is connected to said condenser via the cold thermal storage medium circuit. (The evaporative ice storage arrangement of the present invention is also descriptively referred to herein as sub-triple-point evaporation arrangement.)
Thus, it is understood that where the sub-triple-point evaporation arrangement operates in connection with a standard TEES system, then ice is produced in the sub-triple-point evaporation arrangement during the TEES charging cycle (via working fluid evaporation), while ice would be consumed during the TEES discharging cycle (via working fluid condensation).
Utilisation of the sub-triple-point evaporation arrangement (also referred to herein as the evaporative ice storage arrangement) of the present invention is highly advantageous for the transcritical TEES system because relatively small approach temperatures are achievable.
In a preferred embodiment, a further heat exchanger positioned in the cold thermal storage medium circuit at the outlet of said condenser and an inlet of the cold slurry storage tank in the discharging cycle system.
In an alternative embodiment, the heat exchanger and the cold slurry storage tank are directly coupled together in both the charging cycle system and the discharging cycle system. In the present invention, the cold thermal storage medium may be water or a mixture of water and at least one further component. The vacuum evaporation chamber comprises a spraying device adapted to spray the cold thermal storage medium into the chamber where triple point conditions are maintained. A disadvantage associated with known ice production through desublimation of vapor at a condenser surface is that ice accumulation on heat exchange surfaces results in a deterioration of the heat transfer coefficient. However, the present invention overcomes this problem. Specifically, in a preferred embodiment, the heat exchanger comprises a housing containing cooling conduits and the evaporative ice storage arrangement includes a periodically activated means to defrost ice from the conduits in the heat exchanger in the charging cycle system.
In accordance with yet another aspect of the present invention a method is provided for storing and retrieving electrical energy in a thermoelectric energy storage system having a hot side and a cold side. The method comprising charging the system by transferring thermal energy to a hot thermal storage medium on the hot side and to a cold thermal storage medium on the cold side, and discharging the system by retrieving thermal energy from the hot thermal storage medium and the cold thermal storage medium and transforming the thermal energy into electrical energy via mechanical energy. The step of transferring thermal energy to the cold thermal storage medium comprises forming ice through desublimation evaporation in an evaporative ice storage arrangement. The step of retrieving thermal energy from the cold thermal storage medium comprises melting the ice through condensation in the evaporative ice storage arrangement.
Advantageously, exchanging latent heat with ice allows for relatively compact cold storage and relatively small mass flows when compared with sensible-heat water storages. Thus, the footprint of the TEES system is reduced when connected to the evaporative ice storage of the present invention.
In a preferred embodiment, the step of forming ice through desublimation evaporation in an evaporative ice storage arrangement includes periodically defrosting ice from the conduits in the heat exchanger.
The working fluid is preferably carbon dioxide (C02), or may comprise ammonia (NH3) and/or an organic fluid (such as methane, propane or butane) and/or a refrigerant fluid (such as R 134a (1 ,1 ,1 ,2-Tetrafluoroethane), R245 fa (1 ,1 ,1 ,3,3-Pentafluoropropane)).
Advantageously, the evaporative ice storage technology of the present invention can be used in various commercial applications for energy efficiency improvements and load leveling, especially for processes with periodical switching between ice production and ice melting. Examples include air conditioning and district cooling as well as gas turbine air inlet cooling, in which ice could be generated during nighttime and consumed during daytime. It is also envisaged that other applications without such periodical switching could also benefit from the present invention; for example, in food processing applications or in mine cooling.
Further advantage is gained in that the instant invention does not require a compressor to function and therefore the high costs and space requirements associated with compressors are avoided. If technically possible but not explicitly mentioned, also combinations of embodiments of the invention described in the above and in the following may be embodiments of the method and the system. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter of the invention will be explained in more detail in the following text with reference to preferred exemplary embodiments, which are illustrated in the attached drawings, in which:
Figure 1 shows a simplified schematic diagram of a charging cycle of a thermoelectric energy storage system of the present invention having an evaporative ice storage arrangement; Figure 2a shows a simplified schematic diagram of a discharging cycle of a thermoelectric energy storage system of the present invention having an evaporative ice storage arrangement;
Figure 2b shows a simplified schematic diagram of an alternative embodiment of a discharging cycle of a thermoelectric energy storage system of the present invention having an evaporative ice storage arrangement;
Figure 3 shows an ideal entropy-temperature diagram of the cycles in a transcritical TEES system; Figure 4 shows an entropy-temperature diagram of the cycles in a transcritical TEES system using real mechanical components (turbo machines) and the evaporative ice storage arrangement of the present invention with very small approach temperatures between I and II.
For consistency, the same reference numerals are used to denote similar elements illustrated throughout the figures.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Figures 1 and 2 schematically depict a charging cycle system and a discharging cycle system, respectively, of a sub-triple-point evaporation arrangement in accordance with an embodiment of the present invention, when connected to a TEES system. The charging cycle system 10 shown in Figure 1 comprises a working fluid circuit of a work recovering expander 12, an evaporator 14, a compressor 16 and a heat exchanger 18. A working fluid circulates through these components as indicated by the solid line with arrows in Figure 1 . The system further comprises a cold-fluid storage tank 20 and a hot- fluid storage tank 22 containing a fluid thermal storage medium, coupled together via the heat exchanger 18. The thermal storage medium flows between these components as indicated by the dashed line with arrows in Figure 1 . The system includes a sub-triple- point evaporation arrangement 24 comprising an ice slurry storage tank 26 and a vacuum evaporator chamber 28 and the evaporator 14. Water, in various states, circulates through the components of the sub-triple-point evaporation arrangement 24. The circulation of the water is indicated by the dotted line with arrows in Figure 1 (although the direct connection between the evaporator 14 and the ice slurry storage tank 26 is an optional feature).
In operation, the charging cycle system 10 performs a transcritical cycle and the working fluid flows around the TEES system in the following manner. The working fluid in the evaporator 14 absorbs heat from the sub-triple-point evaporation arrangement 24 and evaporates. The vaporized working fluid is circulated to the compressor 16 and surplus electrical energy is utilized to compress and heat the working fluid to a supercritical state. (In such a supercritical state, the fluid is above the critical temperature and critical pressure.) The working fluid is fed through the heat exchanger 18 where the working fluid discards heat energy into the thermal storage medium. It is noted that in the heat exchanger 18 the working fluid pressure will be above the critical pressure, however the working fluid temperature may go below the critical temperature. Therefore, whilst the working fluid enters the heat exchanger 18 in a supercritical state, it may leave the heat exchanger 18 in a subcritical state. A transcritical cycle is defined as a thermodynamic cycle where the working fluid goes through both subcritical and supercritical states. There is no distinction between a gas phase and a vapor phase beyond the supercritical pressure and therefore there is no evaporation or boiling (in the regular meaning) in the transcritical cycle.
The compressed working fluid exits the heat exchanger 18 and enters the work recovering expander 12. Here the working fluid is expanded to the lower pressure of the evaporator 14. The working fluid flows from the expander 12 back into the evaporator 14. The thermal storage medium is pumped from the cold-fluid storage tank 20 through the heat exchanger 18 to the hot-fluid storage tank 22. The heat energy discarded from the working fluid into the thermal storage medium is stored in the form of sensible heat.
In operation, the sub-triple-point evaporation arrangement 24 functions in the following manner during the charging cycle. Water in liquid form is sprayed into the vacuum evaporation chamber 28 to significantly enhance the evaporation surface. Triple point conditions are at least approximately maintained in the chamber and so part of the water droplets evaporate and consequently another part of the water droplets freeze to form ice in the evaporation chamber 28 as ice/water slurry (the ratio of water mass evaporated to frozen water is approximately 1 to 7.). The ice produced in the vacuum evaporation chamber 28 is pumped to the ice slurry storage tank 26 (also referred to herein as the cold slurry storage tank). The water vapor produced in the vacuum evaporation chamber 28 flows into the evaporator 14 and deposits (or "desublimates") on the evaporator surfaces as ice.
As mentioned, conditions maintained in the vacuum evaporation chamber 28 preferably correspond at least approximately to triple point conditions of water, which in the present embodiment serves as cold thermal storage medium. In particular, a temperature and/or pressure is maintained at values between 10% below and/or 5% above of the corresponding triple point values, preferably at values between 3% below and/or 1 % above, and most preferably at values between 1 % below and or 0.2% above.
The evaporator comprises a housing containing cooling conduits. As described above, the water vapor in the evaporator 14 is deposited on the surface of the cooling conduits, forming a layer of ice. The character of the deposited ice can range from layer of solid ice through to mushy ice, dependent upon factors such as the material of the conduits, the supercooling of the wall, and so forth. The dimensions of the evaporator 14 are adapted to allow optimal removal of the heat from the sub-triple-point evaporation arrangement by evaporation of the working fluid passing through or flowing around the cooling conduits.
The discharging cycle system 30 shown in Figure 2a comprises a working fluid circuit of a pump 32, a heat exchanger 18, a turbine 34, and a condenser 36. A working fluid circulates through these components as indicated by the solid line with arrows in Figure 2a. The system further comprises a cold-fluid storage tank 20 and a hot-fluid storage tank 22 containing a fluid thermal storage medium coupled together via the heat exchanger 18. The thermal storage medium flows between these components as indicated by the dashed line with arrows in Figure 2a. The system also includes a sub-triple-point evaporation arrangement 24 comprising an ice slurry storage tank 26, a slurry heat exchanger 40 and the condenser 36. Water, in various states, circulates through the components of the sub-triple-point evaporation arrangement 24 and through the condenser 36. The circulation of the water is indicated by the dotted line with arrows in Figure 2a. In operation, the discharging cycle system also performs a transcritical cycle and the working fluid flows around the TEES system in the following manner. Heat energy is transferred from the thermal storage medium to the working fluid causing the working fluid to go through transcritical heating. The working fluid then exits the heat exchanger 18 in a supercritical state and enters the turbine 34 where the working fluid is expanded thereby causing the turbine 34 to generate electrical energy. Next, the working fluid passes through the condenser 36 and subsequently the slurry heat exchanger 40, where the working fluid is condensed by exchanging heat energy with the sub-triple-point evaporation arrangement 24. The condensed working fluid exits the sub-triple-point evaporation arrangement 24 via an outlet and is pumped again beyond its critical pressure into the heat exchanger 18 via the pump 32. During the discharging cycle, the sub-triple-point evaporation arrangement 24 functions in the following manner. Initially, the working fluid in gas phase enters the condenser 36 and increases the temperature in the condenser 36 as it condenses. This partially melts the ice built up on the cooling conduits during the charging cycle causing it to drop off the conduits and it is transferred to the ice slurry storage tank 26. Both the ice slurry and the working fluid after exiting the condenser 36 may be subsequently circulated through the slurry heat exchanger 40 where the temperature of the working fluid is reduced thereby condensing the remaining working fluid vapor and consequently ice in the slurry is subsequently melted.
Figure 2b illustrates an alternative discharging cycle system which similarly comprises a working fluid circuit of a pump 32, a heat exchanger 18, a turbine 34 and a condenser 36. However, in this embodiment a separate slurry heat exchanger is not required, as the function of the slurry heat exchanger is performed by directing the water circuit through the condenser. The further features of this alternative discharging cycle system are identical to those described in respect of Figure 2a.
The solid-line quadrangle shown in the entropy-temperature diagram of Figure 3 represents both the ideal charging and ideal discharging cycles of a standard transcritical TEES system in which on the cold side latent heat is exchanged with the surroundings at ambient temperature. Specifically, the charging cycle, as illustrated, follows a counterclockwise direction and the transcritical discharging cycle follows a clockwise direction. The working fluid is assumed to be carbon dioxide for this exemplary embodiment. In this diagram, latent heat exchange at constant temperature with increasing entropy between point I and point II can clearly be seen and also isentropic compression and expansion with increasing temperature between point II and point III can be seen for charging and discharging, respectively. In the exemplary embodiment shown in Figure 3, the entropy of the working fluid falls from 1.70 KJ/kg-K to 1.20 KJ/kg-K during the transcritical cooling by sensible heat exchange between point III, at 120°C, and point IV, at 42°C, in the charging cycle. The transition between point IV and point I occurs with a change in temperature and isentropic compression and expansion for discharging and charging, respectively.
Figure 4 shows an entropy-temperature diagram of the charging and discharging cycles in a transcritical TEES system using the sub-triple-point evaporation arrangement 24 of the present invention. The charging cycle is indicated by a dotted line and follows a counterclockwise direction and the discharging cycle is indicated by a solid line and follows a clockwise direction. The working fluid is assumed to be carbon dioxide for this exemplary embodiment. Latent heat exchange at constant temperature with increasing entropy between point I and point II can clearly be seen. During the charging cycle heat is transferred from the cold storage fluid at 0°C to the working fluid at -°2 C. Inversely, during discharging heat is transferred from the working fluid at 1 °C to the cold storage fluid at 0°C. Point I and point II in Figure 4 can be equated with the working fluid passing through the evaporator 14 in Figure 1 and the condenser 36 in Figures 2a and 2b.
Polytropic compression and expansion with increasing temperature between point II and point III can be seen for charging and discharging, respectively. As a consequence of thermodynamic irreversibilities, such as non zero approach temperatures in the heat exchangers and non isentropic compression and expansion in the turbomachines, the charging cycle and discharging cycle follow differing entropy-temperature paths. In the exemplary embodiment shown in Figure 4, the entropy of the working fluid falls from -0.8 KJ/kg-K to -1 .6 KJ/kg-K during the transcritical cooling by sensible heat exchange between point III, at 120°C, and point IV, at 12°C, in the charging cycle. The transition between point IV and point I occurs with a change in temperature and polytropic compression and expansion for discharging and charging, respectively. Point IV in Figure 4 can be equated with the working fluid passing through section A of the working fluid circuit in Figures 1 , 2a and 2b. Thus, it will be clear to the skilled person that the heat transfer on the cold side heat exchanger is isothermal. Importantly, the sub-triple-point evaporation arrangement can be run at small approach temperatures due to latent heat exchange with ice on the cold side of the TEES and thus the sub-triple-point evaporation arrangement of the present invention has greater efficiency than a system exchanging sensible heat on the cold side, e.g. with a cold river.
The relative size of the evaporator component 14 in the charging cycle system (and equivalently the condenser component 36 in the discharging cycle) is an important factor in the efficient functioning of the sub-triple-point evaporation arrangement. Specifically, the surface area of the cooling conduits in the desublimation evaporator 14 are sized so that it balances well the power duty requirement, allowing enough surface area to limit the ice thickness. The deposition heat transfer conditions of the evaporator 14 are such that the thermal resistance is dominated typically by the ice layer depositing on the condenser tube surface. Thus, the deposition heat transfer is mitigated where the layer becomes thicker than about 3 mm, although the evaporator component performance is still acceptable even where the ice layer thickness is 10 mm. For example, in an exemplary sub-triple-point evaporation arrangement 24 having an ice making duty of 10 MW thermal and cooling conduits of 10mm outer diameter, an ice layer of 7.5mm thickness may be built up after 8 hours charging cycle.
It will be clear to those skilled in the art that as the ice layer builds on the cooling conduits in the desublimation evaporator 14, the overall power of the ice production is reduced with time. To maintain constant ice making duty, the spraying of water in the vacuum evaporation chamber 28 can be used to control the conditions in such a way that continuous duty is achieved during the whole charging cycle. For example, at the beginning of a charging cycle, when there is little or no ice deposition built up on the cooling conduits, the mass flow of water sprayed in the vacuum evaporation chamber 28 can be at a relatively lower level and then gradually increased to maintain a constant overall heat transfer coefficient of the whole charging cycle as the ice build-up gradually reduces the heat transfer.
In an alternative embodiment, the arrangement 24 can be adapted such that a relatively small quantity of a dilute solution of highly water soluble inorganic salts is sprayed in the evaporator 14 over the cooling conduits. The resulting ice morphology is softer and more powdery in nature. Such ice may drop from the cooling conduits under its own weight down to the base of the evaporator housing where an outlet pipe may be located or such ice may be periodically "washed down" from the cooling conduits using pressure washer ports.
In a further alternative embodiment, additional warmer working fluid is periodically injected into the cooling conduits in the evaporator 14 during charging which causes the ice built up to melt. Where the sub-triple-point evaporation arrangement is part of a TEES system, such defrosting may only be required every 2 or 3 hours. In such an embodiment, several evaporator modules connected in parallel to the evaporation chamber can be used to ensure continuous operation of the charging cycle because even as the ice is melted in one of the evaporator modules, ice production is ongoing in the other modules. Advantageously, in such an embodiment, the evaporator dimensions can be smaller than those of the main embodiment described herein. In an alternative embodiment of the present invention, the water sprayed into the vacuum evaporator chamber 28 of the sub-triple-point evaporation arrangement may be a mixture of water with another liquid such as ethanol or glycol. In this case, preferably triple point conditions of a predominant component in the mixture are at least approximately maintained in the vacuum chamber as detailed above.
Whilst the charging cycle system 10 of Figure 1 and the discharging cycle systems 30 of Figures 2a and 2b have been illustrated separately, the heat exchanger 18, cold-fluid storage 20, hot-fluid storage 22 and thermal storage medium of the TEES system are preferably common to both cycles. The desublimation evaporator 14 and the condenser 36 in the sub-triple-point evaporation arrangement 24 may be the same apparatus operated in opposing directions for the charging and discharging cycles respectively. Similarly the turbine 34 and the compressor 16 roles as well as the pump 32 / expander 12 roles may be carried out by the same machinery, capable of achieving both tasks. The charging and discharging cycles may be performed consecutively, not simultaneously.
In an alternative embodiment of the sub-triple-point evaporation arrangement 24 of the present invention, a pipe may be connected directly between the evaporator 14 and the ice slurry storage tank 26 during a charging cycle. Parts of the ice building up on the evaporator which are spontaneously released or actively removed may be moved to the ice slurry storage tank 26 via said pipe.
It is noted that on the hot side of a TEES, the temperature difference between the thermal storage medium and the working fluid may be reduced using intermediate storage tanks as described in the applicant's earlier patent application EP09163084 and thereby increasing the system efficiency.
In the present embodiment, the heat exchanger is a counterflow heat exchanger, and the working fluid of the cycle is preferably carbon dioxide. Further, the thermal storage medium is a fluid, and is preferably water. In a preferred embodiment, the compressor 16 is an electrically powered compressor.
In a preferred embodiment of the present invention, the counterflow heat exchanger may have a minimal approach temperature, ATmin, of 3 K (ie. the minimal temperature difference between the two fluids exchanging heat is 3 K). The approach temperature should be as small as possible.
In the present embodiment, the evaporator 14 is a vertically oriented desublimation evaporator of the "shell and tube" type, having working fluid circulating inside of the "tubes" (referred to as conduits herein), and the water vapor on the "shell" side. Advantageously, the surface of the cooling conduits can be increased by utilizing cross sections other than circular, or by the addition of fins. The fins improve the deposition heat transfer by the increasing surface, but also by reducing the thickness of the deposited ice which builds up over a larger surface.
The preferred working fluid for circulating in the TEES system is carbon dioxide; mainly due to the higher efficiencies in heat transfer processes and the amiable properties of carbon dioxide as a natural working fluid i.e. non-flammable, no ozone depletion potential, no health hazards etc. Whilst the thermal storage medium in the hot side of the TEES system is generally water (if necessary, in a pressurized container), other materials, such as oil or molten salt, may also be used.
Preferred embodiments of the present invention, in particular as described above, may be realized as detailed in the items listed below, advantageously in combination with one or more of the features as detailed above:
1 . A thermoelectric energy storage system having a charging cycle (10) for providing thermal energy to a hot thermal storage arrangement (18, 20, 22) and an evaporative ice storage arrangement (24), and a discharging cycle (30) for generating electricity by retrieving the thermal energy from the hot thermal storage arrangement (18, 20, 22) and the evaporative ice storage arrangement (24), the thermoelectric energy storage system comprising; a working fluid circuit adapted to circulate a working fluid through the hot thermal storage arrangement (18, 20, 22) and the evaporative ice storage arrangement (24), characterized in that; the evaporative ice storage arrangement (24) comprises a heat exchanger (14, 36) coupled to an cold slurry storage tank (26) via a cold thermal storage medium circuit, wherein in the charging cycle system (10), the heat exchanger is adapted to function as a desublimation evaporator (14), and an evaporation chamber (28) is coupled between said desublimation evaporator (14) and the cold slurry storage tank (26) in the cold thermal storage medium circuit, in the discharging cycle system (30), the heat exchanger is adapted to function as a condenser (36), and the cold slurry storage tank (26) is connected to said condenser (36) via the cold thermal storage medium circuit.
2. The system according to item 1 , further comprising a further heat exchanger (40) positioned in the cold thermal storage medium circuit at the outlet of said condenser (36) and an inlet of the cold slurry storage tank (26) in the discharging cycle system (30).
3. The system according to any preceding item, wherein the heat exchanger (14, 36) and the cold slurry storage tank (26) are directly coupled together in both the charging cycle system (10) and the discharging cycle system (30).
4. The system according to any preceding item, wherein the evaporation chamber (28) comprises a spraying device adapted to spray the cold thermal storage medium into the evaporation chamber (28) where triple point conditions are maintained.
5. The system according to any preceding item, wherein the cold thermal storage medium is water.
6. The system according to any preceding item, wherein the cold thermal storage medium is a mixture of water and at least one further component.
7. The system according to any preceding item, wherein the heat exchanger (14, 36) comprises a housing containing cooling conduits and the evaporative ice storage arrangement (24) includes a periodically activated means to defrost ice from the conduits in the heat exchanger (14) in the charging cycle system (10). 8. A method for storing and retrieving electrical energy in a thermoelectric energy storage system having a hot side and a cold side, comprising;
charging the system by transferring thermal energy to a hot thermal storage medium on the hot side and to a cold thermal storage medium on the cold side,
discharging the system by retrieving thermal energy from the hot thermal storage medium and the cold thermal storage medium and transforming the thermal energy into electrical energy via mechanical energy,
wherein the step of transferring thermal energy to the cold thermal storage medium comprises;
forming ice through desublimation evaporation in an evaporative ice storage arrangement (24),
and the step of retrieving thermal energy from the cold thermal storage medium comprises;
melting the ice through condensation in the evaporative ice storage arrangement
(24).
9. The method according to item 8, wherein the step of forming ice through desublimation evaporation in an evaporative ice storage arrangement (24) includes periodically defrosting ice from the conduits in the heat exchanger (14).
Thus, it is clear to the skilled person that the present invention has the following advantages; minimal system irreversibilities through gentle heat transfer due to relatively small temperature approaches, low parasitic losses as no large fans or compressors are required, and good scalability as the size of the heat exchanger on the cold side of the cycle may be decoupled from the size of the cold storage.
Importantly, the skilled person will be aware that the sub-triple point evaporative ice storage technology of the present invention can be used in various commercial applications where energy efficiency improvements and load leveling are sought. Examples include air conditioning and district cooling, gas turbine air inlet cooling, food processing, or mine cooling. This list of examples is not exhaustive. While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

Claims

CLAIMS 1 ) A thermoelectric energy storage system comprising a) a hot thermal storage arrangement comprising one or more hot storage heat exchangers (18), b) a cold thermal storage arrangement comprising one or more cold storage heat exchangers (14, 36, 40), c) a thermodynamic cycle unit comprising i) at least one working fluid circuit for circulating one or more working fluids through at least one hot storage heat exchanger (18) as well as through at least one cold storage heat exchanger (14, 36, 40), each working fluid circuit further comprising ii) at least one compressor or pump (16, 32) for compressing the at least one working fluid, iii) at least one expander (12, 34), preferably a turbine or an expansion valve, for expanding the at least one working fluid, iv) the thermodynamic cycle unit configured to
(1 ) transfer thermal energy from the cold storage unit to the hot storage unit in a charging mode,
(2) convert thermal energy from the hot storage unit into mechanical and subsequently electric energy in a discharging mode,
characterized in that
d) the cold storage arrangement comprises
i) a cold thermal storage medium,
ii) a vacuum evaporation chamber (28) adapted to evaporate liquid phase cold thermal storage medium to obtain solid phase cold thermal storage medium and gaseous phase cold thermal storage medium,
iii) a first fluid connection for supplying gaseous phase cold thermal storage medium from said vacuum evaporation chamber (28) to at least one cold storage heat exchanger for evaporating working fluid through desublimation of cold thermal storage medium during the charging cycle,
iv) a second fluid connection for connecting said vacuum evaporation chamber to a cold slurry storage tank for storing a mixture of solid phase cold thermal storage medium and liquid phase cold thermal storage medium during the charging cycle, v) a third fluid connection for connecting said cold slurry storage tank to at least one cold storage heat exchanger for cooling or condensing working fluid during the discharge cycle.
2) The thermoelectric energy storage system of claim 1 , wherein the first fluid connection and the third fluid connection connect to the same cold storage heat exchanger (14, 36). 3) The thermoelectric energy storage system of claim 1 , wherein the cold storage heat exchanger (14, 36) is adapted to function as a desublimation evaporator (14) in the charging mode, and as condenser (36) in the discharging mode.
4) The thermoelectric energy storage system according to any preceding claim, wherein the cold storage heat exchanger (14, 36) and the cold slurry storage tank (26) are directly coupled together in both the charging mode and the discharging mode.
5) The thermoelectric energy storage system according to claim 1 , wherein the first fluid connection connects to a first cold storage heat exchanger (14, 36) and the third fluid connection connects to a second cold storage heat exchanger (40).
6) The thermoelectric energy storage system according to the preceding claim, wherein the second cold storage heat exchanger (40) is positioned after an outlet of the first cold storage heat exchanger (14, 36) in the discharging mode.
7) The thermoelectric energy storage system according to the preceding claim, wherein the second cold storage heat exchanger (40) is positioned before an inlet of the cold slurry storage tank (26) in the discharging mode. 8) The thermoelectric energy storage system according to claim 5, 6 or 7, characterized in that the cold storage arrangement comprises a fourth fluid connection to allow for a transfer of solid cold thermal storage medium from the first cold storage heat exchanger (14, 36) to the cold slurry storage tank (26) in a discharging mode. 9) The thermoelectric energy storage system according to any preceding claim, wherein the evaporation chamber (28) comprises a spraying device adapted to spray the cold thermal storage medium into the evaporation chamber (28) where triple point conditions of the cold thermal storage medium are at least approximately maintained.
10) The thermoelectric energy storage system according to any preceding claim, wherein the cold thermal storage medium is water.
1 1 ) The thermoelectric energy storage system according to any preceding claim, wherein the cold thermal storage medium is a mixture of water and at least one further component.
12) The thermoelectric energy storage system according to any preceding claim,
comprising one or more valves allowing for selective opening, closing and/or throttling on or more fluid connections.
13) A method for storing energy in a thermoelectric energy storage system, said
thermoelectric energy storage system comprising
a) a hot thermal storage arrangement,
b) a cold thermal storage arrangement,
c) a thermodynamic cycle unit comprising
i) at least one working fluid circuit for circulating one or more working fluids through the hot thermal storage arrangement as well as through the cold thermal storage arrangement, each working fluid circuit further comprising ii) at least one compressor or pump (16, 32) for compressing the working fluid, iii) at least one expander (12, 34), preferably a turbine or an expansion valve, for expanding the working fluid,
d) the method comprising the steps of
i) transferring, by means of the thermodynamic cycle unit, thermal energy from the cold storage arrangement to the hot storage arrangement in a charging mode,
ii) converting, by means of the thermodynamic cycle unit, thermal energy from the hot storage arrangement into mechanical and subsequently electric energy in a discharging mode,
characterized in that e) in the charging mode
i) a liquid cold thermal storage medium is evaporated in a vacuum
evaporation chamber (28) to obtain solid phase cold thermal storage medium and gaseous phase cold thermal storage medium, ii) gaseous phase cold thermal storage medium from said vacuum
evaporation chamber (28) is desublimated in the cold thermal storage unit in order to evaporate at least one working fluid,
iii) a mixture of solid phase cold thermal storage medium and liquid phase cold thermal storage medium is stored in a cold slurry tank (26); f) in the discharging mode
i) solid phase cold thermal storage medium from the cold slurry tank (26) is used to cool or condense at least one working fluid.
14) The method according to claim 13, wherein triple point conditions of the cold thermal storage medium are at least approximately maintained in the vacuum evaporation chamber (28).
15) The method according to claim 13 or 14, wherein step e) includes periodically
defrosting a desublimation surface of the cold thermal storage unit, in particular defrosting the conduits of a heat exchanger (14) employed for desublimating gaseous cold thermal storage medium in order to evaporate working fluid.
PCT/EP2012/060988 2011-06-09 2012-06-11 Thermoelectric energy storage system with an evaporative ice storage arrangement and method for storing thermoelectric energy Ceased WO2012168472A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP11169311.5 2011-06-09
EP11169311A EP2532843A1 (en) 2011-06-09 2011-06-09 Thermoelectric energy storage system with an evaporative ice storage arrangement and method for storing thermoelectric energy

Publications (2)

Publication Number Publication Date
WO2012168472A2 true WO2012168472A2 (en) 2012-12-13
WO2012168472A3 WO2012168472A3 (en) 2014-05-30

Family

ID=45541146

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2012/060988 Ceased WO2012168472A2 (en) 2011-06-09 2012-06-11 Thermoelectric energy storage system with an evaporative ice storage arrangement and method for storing thermoelectric energy

Country Status (2)

Country Link
EP (1) EP2532843A1 (en)
WO (1) WO2012168472A2 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9695715B2 (en) 2014-11-26 2017-07-04 General Electric Company Electrothermal energy storage system and an associated method thereof
WO2019046430A1 (en) * 2017-08-29 2019-03-07 Arizona Board Of Regents On Behalf Of Arizona State University Carbon dioxide upgrade and energy storage system and method
WO2022218486A1 (en) * 2021-04-14 2022-10-20 Stiesdal Storage A/S Thermal energy storage system with a spray of phase change material and method of its operation
JP2022551711A (en) * 2019-10-09 2022-12-13 シンクロスター・リミテッド Apparatus and method for storing energy as heat

Families Citing this family (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10094219B2 (en) 2010-03-04 2018-10-09 X Development Llc Adiabatic salt energy storage
DE102012206296A1 (en) * 2012-04-17 2013-10-17 Siemens Aktiengesellschaft Plant for storage and delivery of thermal energy and method of operation thereof
GB2501683A (en) * 2012-04-30 2013-11-06 Isentropic Ltd Energy storage apparatus
GB2501685A (en) * 2012-04-30 2013-11-06 Isentropic Ltd Apparatus for storing energy
WO2014052927A1 (en) 2012-09-27 2014-04-03 Gigawatt Day Storage Systems, Inc. Systems and methods for energy storage and retrieval
FR3011626B1 (en) 2013-10-03 2016-07-08 Culti'wh Normands THERMODYNAMIC SYSTEM FOR STORAGE / ELECTRIC POWER GENERATION
PL2927435T3 (en) 2014-04-01 2017-12-29 General Electric Technology Gmbh A system for reversibly storing electrical energy as thermal energy
CN106716040A (en) * 2014-09-30 2017-05-24 西门子公司 Storage and charging system and method with high temperature heat energy exchange system
US10465565B2 (en) 2016-12-02 2019-11-05 General Electric Company Method and system for carbon dioxide energy storage in a power generation system
US10458284B2 (en) 2016-12-28 2019-10-29 Malta Inc. Variable pressure inventory control of closed cycle system with a high pressure tank and an intermediate pressure tank
US10082045B2 (en) 2016-12-28 2018-09-25 X Development Llc Use of regenerator in thermodynamic cycle system
US11053847B2 (en) 2016-12-28 2021-07-06 Malta Inc. Baffled thermoclines in thermodynamic cycle systems
US10233833B2 (en) 2016-12-28 2019-03-19 Malta Inc. Pump control of closed cycle power generation system
US10233787B2 (en) 2016-12-28 2019-03-19 Malta Inc. Storage of excess heat in cold side of heat engine
US10280804B2 (en) 2016-12-29 2019-05-07 Malta Inc. Thermocline arrays
US10221775B2 (en) 2016-12-29 2019-03-05 Malta Inc. Use of external air for closed cycle inventory control
US10801404B2 (en) 2016-12-30 2020-10-13 Malta Inc. Variable pressure turbine
US10082104B2 (en) 2016-12-30 2018-09-25 X Development Llc Atmospheric storage and transfer of thermal energy
US10436109B2 (en) 2016-12-31 2019-10-08 Malta Inc. Modular thermal storage
US10488085B2 (en) 2017-05-24 2019-11-26 General Electric Company Thermoelectric energy storage system and an associated method thereof
EP4451551A3 (en) 2018-01-11 2025-01-22 Lancium Llc Method and system for dynamic power delivery to a flexible datacenter using unutilized energy sources
IT201900002385A1 (en) 2019-02-19 2020-08-19 Energy Dome S P A Plant and process for the accumulation of energy
WO2021097413A1 (en) 2019-11-16 2021-05-20 Malta Inc. Pumped heat electric storage system
IT202000003680A1 (en) 2020-02-21 2021-08-21 Energy Dome S P A Plant and process for the accumulation of energy
BR112023002535A2 (en) 2020-08-12 2023-04-18 Malta Inc PUMPED THERMAL ENERGY STORAGE SYSTEM WITH STEAM CYCLE
US11486305B2 (en) 2020-08-12 2022-11-01 Malta Inc. Pumped heat energy storage system with load following
EP4296477A3 (en) 2020-08-12 2024-02-28 Malta Inc. Pumped heat energy storage system with modular turbomachinery
US11396826B2 (en) 2020-08-12 2022-07-26 Malta Inc. Pumped heat energy storage system with electric heating integration
US11286804B2 (en) 2020-08-12 2022-03-29 Malta Inc. Pumped heat energy storage system with charge cycle thermal integration
US11454167B1 (en) 2020-08-12 2022-09-27 Malta Inc. Pumped heat energy storage system with hot-side thermal integration
US11480067B2 (en) 2020-08-12 2022-10-25 Malta Inc. Pumped heat energy storage system with generation cycle thermal integration
JP7554920B2 (en) 2020-09-25 2024-09-20 エナジー ドーム エス．ピー．エー． Plants and processes for energy storage
CN112943393B (en) * 2021-03-09 2022-12-09 西安交通大学 Geothermal energy thermochemistry and compressed air composite energy storage system and operation method thereof
EP4430285A4 (en) 2021-12-14 2025-11-26 Malta Inc INTEGRATED PUMPED HEAT STORAGE SYSTEM WITH COAL-FIRED POWER GENERATION UNIT
CN116592680B (en) * 2023-04-18 2026-02-27 北京博睿鼎能动力科技有限公司 Multi-flow waste heat storage tank

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0916308A1 (en) 1997-11-17 1999-05-19 Ge Yokogawa Medical Systems, Ltd. Ultrasonic diagnostic apparatus, cursor display method and measuring apparatus
EP2157317A2 (en) 2008-08-19 2010-02-24 ABB Research LTD Thermoelectric energy storage system and method for storing thermoelectric energy
EP2275649A1 (en) 2009-06-18 2011-01-19 ABB Research Ltd. Thermoelectric energy storage system with an intermediate storage tank and method for storing thermoelectric energy

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1568271A (en) * 1968-03-25 1969-05-23
DE3736112C2 (en) * 1987-10-26 1997-01-09 Ghalamfarsa Chahp Mostofizadeh Process for the production of ice suspensions
US5448892A (en) * 1991-04-29 1995-09-12 Cheng; Chen-Yen Methods and apparatuses for providing cool thermal storage and/or water purification
JPH1114172A (en) * 1997-06-23 1999-01-22 Toyo Eng Works Ltd Binary codling facility and binary cooling method utilizing heat storage of dry ice
US20020108739A1 (en) * 1999-08-13 2002-08-15 Sing-Wang Cheng Heat temperature raising system
EP2312129A1 (en) * 2009-10-13 2011-04-20 ABB Research Ltd. Thermoelectric energy storage system having an internal heat exchanger and method for storing thermoelectric energy

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0916308A1 (en) 1997-11-17 1999-05-19 Ge Yokogawa Medical Systems, Ltd. Ultrasonic diagnostic apparatus, cursor display method and measuring apparatus
EP2157317A2 (en) 2008-08-19 2010-02-24 ABB Research LTD Thermoelectric energy storage system and method for storing thermoelectric energy
EP2275649A1 (en) 2009-06-18 2011-01-19 ABB Research Ltd. Thermoelectric energy storage system with an intermediate storage tank and method for storing thermoelectric energy

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9695715B2 (en) 2014-11-26 2017-07-04 General Electric Company Electrothermal energy storage system and an associated method thereof
WO2019046430A1 (en) * 2017-08-29 2019-03-07 Arizona Board Of Regents On Behalf Of Arizona State University Carbon dioxide upgrade and energy storage system and method
US10954825B2 (en) 2017-08-29 2021-03-23 Arizona Board Of Regents On Behalf Of Arizona State University System and method for carbon dioxide upgrade and energy storage using an ejector
JP2022551711A (en) * 2019-10-09 2022-12-13 シンクロスター・リミテッド Apparatus and method for storing energy as heat
WO2022218486A1 (en) * 2021-04-14 2022-10-20 Stiesdal Storage A/S Thermal energy storage system with a spray of phase change material and method of its operation
US12000660B1 (en) 2021-04-14 2024-06-04 Stiesdal Storage A/S Thermal energy storage system with a spray of phase change material and method of its operation

Also Published As

Publication number Publication date
WO2012168472A3 (en) 2014-05-30
EP2532843A1 (en) 2012-12-12

Similar Documents

Publication Publication Date Title
EP2532843A1 (en) Thermoelectric energy storage system with an evaporative ice storage arrangement and method for storing thermoelectric energy
EP2157317B1 (en) Thermoelectric energy storage system and method for storing thermoelectric energy
US10965191B2 (en) Thermodynamic system for storing/producing electrical energy
EP2182179B1 (en) Thermoelectric energy storage system and method for storing thermoelectric energy
WO2013102537A2 (en) Electro-thermal energy storage system with improved evaporative ice storage arrangement and method for storing electro-thermal energy
US20130087301A1 (en) Thermoelectric energy storage system and method for storing thermoelectric energy
EP2400120A1 (en) Thermoelectric energy storage system
EP2554804B1 (en) Energy storage system with an intermediate storage tank and method for storing thermoelectric energy
EP2241737B1 (en) Thermoelectric energy storage system having two thermal baths and method for storing thermoelectric energy
US20120222423A1 (en) Thermoelectric energy storage system having an internal heat exchanger and method for storing thermoelectric energy
KR102263742B1 (en) Thermodynamic cycle apparatus and method
MX2013002944A (en) A SYSTEM AND METHOD TO STORE ENERGY AND PURIFY FLUID.
Giannetti et al. Cascade refrigeration system with inverse Brayton cycle on the cold side
CN207701188U (en) Construct low-temperature receiver energy-recuperation system and heat engine system
Steinmann Thermo-mechanical storage of electricity at power plant scale
PUMPS International Research & Development Co Ltd, Newcastle upon Tyne, UK
WO2017157924A2 (en) Heat pump apparatus
HK1169160B (en) Transcritical thermally activated cooling, heating and refrigerating system
HK1169160A (en) Transcritical thermally activated cooling, heating and refrigerating system

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12729442

Country of ref document: EP

Kind code of ref document: A2

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12729442

Country of ref document: EP

Kind code of ref document: A2