THERMAL BATTERY AND ELECTRICITY GENERATION SYSTEM

Abstract

A thermal battery includes a heat sink material that remains solid across an operating temperature range (i.e., for all operating modes) of the battery, and a heat conductive material in direct heat transfer relationship with the solid heat sink material. The heat conductive material has a melting point below that of the heat sink material so that in use the heat conductive material is a fluid, for example molten when the heat conductive material is a metal, in the operating temperature range of the battery.

Claims

1. A thermal battery includes: (a) a heat sink material that remains solid across an operating temperature range of the battery, and (b) a heat conductive material in heat transfer relationship with the heat sink material, the heat conductive material having a melting point below that of the heat sink material so that in use the heat conductive material is fluid in the operating temperature range of the battery.

2. (canceled)

3. The thermal battery defined in claim 1 wherein the heat sink material and the heat conductive material are selected on the basis that the materials do not react chemically with each other.

4. (canceled)

5. The thermal battery defined in claim 1 wherein the heat sink material includes graphite.

6. The thermal battery defined in claim 1 wherein the heat conductive material includes any one of a metal, metal alloy and a gas.

7. The thermal battery defined in claim 6 wherein the metal is copper or aluminium and the gas is CO.sub.2, or N.sub.2 or Ar.

8. The thermal battery defined in claim 7 wherein, the operating temperature range of the battery is between 600 C. and up to 2000 C.

9. The thermal battery defined in claim 1 wherein the heat sink material is in the form of a block of material (either cylindrical or rectilinear) or a series or combination of plates both of any suitable shape and size.

10. The thermal battery defined in claim 9 wherein the block of heat sink material is immersed in the heat conductive material.

11. The thermal battery defined in claim 9 wherein the heat sink material includes a void or a plurality of voids: (a) containing the heat conductive material; or (b) through which the heat conductive material comes into contact.

12. (canceled)

13. (canceled)

14. (canceled)

15. The thermal battery defined in claim 1 includes a housing that encloses the heat sink material and the heat conductive material and is formed to thermally insulate the heat sink and the heat conductive material and thereby minimise heat loss via the housing.

16. (canceled)

17. (canceled)

18. (canceled)

19. The thermal battery defined in claim 1 being in a modular plug-and-play unit that can be transported from a manufacturing site to an end-use site and installed and operated on site quickly.

20. The thermal battery defined in claim 1 includes a control system that is operable to control the operation of the thermal battery in a thermal storage mode, a thermal transfer mode, and in a standby mode in which there is not heat transfer to and no thermal transfer from the thermal battery.

21. (canceled)

22. The thermal battery defined in claim 20 wherein the control system is operable to change the operation of the thermal battery from one mode to another mode.

23. The thermal battery defined in claim 20 wherein the control system is responsive to information relating to a range of factors including, by way of example, the availability and cost of energy from the energy source (or energy sources where multiple sources are available), the anticipated demand for electricity (including the power required and the demand time period), and the availability and cost of other sources of electricity during the required demand time period.

24. (canceled)

25. The thermal battery defined in claim 23 wherein the control system includes sensors for monitoring directly or indirectly the temperature of the heat conductive material and/or the heat sink material and the control system includes a controller for processing sensed temperatures and operating the energy input or the energy output from the battery in response to the sensed temperatures.

26. (canceled)

27. An electricity generation system that includes: (a) the thermal battery defined in claim 1 for storing energy as thermal energy; (b) a source of energy connected to the thermal battery for transferring energy to the heat conductive material to transform the heat conductive material to a fluid or maintain the heat conductive material as a fluid; or (c) a source of energy connected to the thermal battery for transferring energy to the heat sink material to convert the energy to thermal energy that is stored in the heat sink material and simultaneously transfer thermal energy to the heat conductive material; and (d) an electricity generation unit connected to the thermal battery for generating electricity from thermal energy transferred to the electricity generation unit from the heat sink material via the fluid heat conductive material.

28. (canceled)

29. The system defined in claim 27 includes an energy transfer unit that, in use, transfers energy from the energy source to the heat conductive material.

30. The system defined in claim 29 wherein the energy transfer unit includes an electric arc unit with electrodes extending into the heat conductive material.

31. The system defined in claim 29 wherein the energy transfer unit includes an inductive heating unit.

32. The system defined in any one of claim 27 includes a thermal energy transfer unit for transferring thermal energy from the fluid heat conductive material to the electricity generation unit.

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0127] The invention is described further by way of example only with reference to the accompanying drawings of which:

[0128] FIG. 1a is a diagram of one embodiment of an electricity generation system in accordance with the invention;

[0129] FIG. 1b is a diagram of another embodiment of an electricity generation system in accordance with the invention;

[0130] FIG. 1c is a diagram of another, although not the only other, embodiment of an electricity generation system in accordance with the invention; and

[0131] FIG. 2a is a top plan view in diagrammatic form of an embodiment of a thermal battery in accordance with the invention that is suitable for use in the electricity generation systems of FIGS. 1a, b and c;

[0132] FIG. 2b is an end elevation of the thermal battery shown in FIG. 2a;

[0133] FIG. 3a is a top plan view in diagrammatic form of another embodiment of a thermal battery in accordance with the invention that is suitable for use in the electricity generation systems of FIGS. 1a, b and c;

[0134] FIG. 3b is an end elevation of the thermal battery shown in FIG. 2a;

[0135] FIG. 4a is a top plan view in diagrammatic form of another embodiment of a thermal battery in accordance with the invention that is suitable for use in the electricity generation systems of FIGS. 1a, b and c;

[0136] FIG. 4b is an end elevation of the thermal battery shown in FIG. 2a;

[0137] FIG. 5a is a top plan view in diagrammatic form of another, although not the only other, embodiment of a thermal battery in accordance with the invention that is suitable for use in the electricity generation systems of FIGS. 1a, 1b, and 1c;

[0138] FIG. 5b is an end elevation of the thermal battery shown in FIG. 2a.

DESCRIPTION OF EMBODIMENTS

[0139] The embodiments of the electricity generation system shown in the Figures are based on a thermal battery, generally identified by the numeral 3 in the Figures.

[0140] The embodiment of the thermal battery 3 shown in FIG. 2a, b includes:

[0141] (a) a block of graphite 15 that acts as a heat sink material that, in use of the thermal battery 3, remains as a solid across an operating temperature range of the battery;

[0142] (b) a plurality of voids 17 formed in the graphite block 15;

[0143] (c) an induction coil 19 wrapped around the graphite block 15 and connected to an external energy source 1 of FIGS. 1a, b and c for providing energy to the thermal battery 3; and

[0144] (d) heat conductive material in the voids 17 to transfer (i) energy from the external energy source 1 to the graphite in a heat storage mode (i.e.

[0145] the above-described Charge Mode) of the battery 3 and (ii) thermal energy from the graphite to an electricity generation unit generally identified by the numeral 5 of FIGS. 1a, b and c in a heat transfer mode of the battery.

[0146] In the embodiment of the thermal battery 3 shown in FIGS. 2a, b, the heat conductive material is a metal, i.e. aluminium in this instance, that is in heat transfer relationship with the graphite block 15 and has a melting point below that of the graphite so that in use the aluminium is molten in the operating temperature range of the battery 3.

[0147] With further reference to FIGS. 2a, b, the voids 17 are cylindrical-shaped and extend into the graphite block 15 from an upper surface of the block. The voids 17 are evenly-spaced within the graphite block 15 so that, in use, there is uniform heating of the graphite via the heat conductive material.

[0148] It is noted that the invention is not confined to cylindrical-shaped voids and the described array of the voids.

[0149] The aluminium is in heat transfer relationship with the graphite block 15. The aluminium has a melting point below that of the graphite. In use, the operating temperature range of the battery, typically 600 C.-2000 C., is selected so that the aluminium melts and forms a molten metal within the operating temperature range of the battery 3. Operating with fluid aluminium facilitates efficient energy transfer in the thermal battery 3.

[0150] The thermal battery 3 shown in FIGS. 2a, b also includes a refractory lined housing 21 that encloses the graphite block 15 and the aluminium and thermally insulates the graphite block 15 and the aluminium. It is noted that the housing 21 does not have to be a pressure vessel.

[0151] With further reference to FIG. 2a, b, in use, argon or any other suitable inert gas is supplied to the volume 23 in the housing 21 via an argon source (not shown) to maintain an inert atmosphere within the housing 21 to prevent reactions occurring between the materials in the housing.

[0152] The graphite block 15 and the voids 17 may be any suitable shape and size.

[0153] The size and shape of the graphite block 15 and the voids 17 may be selected to allow the thermal battery 3 to be fitted into a standard shipping container and be set-up as a plug-and-play unit that can readily be transported to an end-use location such as remote mining operations. Depending on the energy requirements, there may be a plurality of these modular thermal batteries on side and arranged to operate together as part of the electricity generation system.

[0154] The thermal battery 3 also includes a control system (not shown) that is operable to control the operation of the thermal battery 3 in the thermal storage mode (i.e. the above-described Charge Mode), the thermal transfer mode (i.e. the above-described Discharge Mode), and a stand-by mode (i.e. the above-described Passive Mode) in which there is no heat transfer to and no thermal transfer from the thermal battery.

[0155] The control system is also operable to change the operation of the thermal battery from one mode to another mode.

[0156] The control system is responsive to information relating to a range of factors including, by way of example, the availability and cost of energy from the energy source (or energy sources where multiple sources are available), the anticipated demand for electricity (including the power required and the demand time period), and the availability and cost of other sources of electricity during the required demand time period.

[0157] The control system is responsive to operating parameters of the thermal battery, such as the operating temperature of the battery, and includes sensors (not shown) that monitor directly or indirectly the temperature of the heat conductive material and/or the heat sink material.

[0158] The control system may include a controller for processing sensed temperatures and operating the energy input or the energy output from the thermal battery 3 in response to the sensed temperatures. For example, if the temperature reaches a maximum operating temperature, the control system changes the operation of the thermal battery 3 to the Passive mode described above. If the temperature reaches a minimum operating temperature, the control system changes the operation of the thermal battery to the heat storage mode.

[0159] The control system moves the operation of the thermal battery 3 between the modes as required.

[0160] The embodiment of the thermal battery 3 shown in FIGS. 3a, b is conceptually the same as the FIGS. 2a, b embodiment and the same reference numerals are used to describe the same features.

[0161] One main difference between the embodiments is that in the embodiment of FIG. 3a, b the heat conductive material is a gas, such as CO.sub.2, N.sub.2 or Ar, rather than aluminium or another metal. The gas is contained within a volume 23 within the housing 21 that is not occupied by the graphite block 15. The gas is supplied to and removed from the volume 23 via a heat exchanger assembly generally identified by the numeral 25 having inlet/outlet tubes 27 communicating with the volume 23, a cold gas inlet tube 29 communicating with a source of cold gas (not shown), and a hot gas outlet tube 31 communicating with an electrical generation system 5 of FIGS. 1a, b, c.

[0162] The use of gas as the heat conductive material means that it is not absolutely necessary to form voids 17 in the graphite block 15. Having said this, the voids 17 may be provided to improves the surface are for heat transfer.

[0163] In use of the embodiment shown in FIGS. 3a, b, the induction heating coil 19 heats the graphite in the graphite block, and there is heat transfer from the graphite to the gas in the volume 23 during a Charge Mode. In addition, in use, the heated gas is discharged from the volume 23 during a Discharge Mode.

[0164] The embodiments of the thermal battery 3 shown in FIGS. 4a, b and 5a, b are conceptually the same as the FIG. 3a, b embodiment and the same reference numerals are used to describe the same features.

[0165] The main difference between the embodiments is the form of the heat sink material. Instead of the single graphite block 15 shown in FIGS. 3a, b, in the embodiments of FIGS. 4a, b and 5a, b, there is a plurality of smaller, spaced-apart graphite blocks 15. In particular, the graphite blocks in FIGS. 5a, b are donut-shaped. These arrangements provide higher surface areas of contact between the graphite and the gas for improved heat transfer.

[0166] In addition, the embodiments of FIGS. 4a, b and FIGS. 5a, b are continuous flow through arrangements with the housing 21 having an opening for cold gas directly from the gas inlet pipe 29 and an outlet for hot gas for the hot gas tube 21.

[0167] The operation of the embodiments of the thermal battery 3 shown in FIGS. 2-5 as part of the electricity generation system shown in FIGS. 1a, b and c is as follows:

[0168] (a) in a Charge Mode of the thermal battery, energy from the energy source heats the graphite block(s) 15 and the graphite absorbs energy and stores it as heat;

[0169] (b) in a thermal energy transfer mode, i.e. Discharge Mode, of the thermal battery 3, heat is subsequently recovered from the block(s) 15 and is transferred to the electricity generation unit; and

[0170] (c) energy transfer to and from the block(s) 15 is via the conductive material in the fluid state.

[0171] It is noted that the thermal battery 3 of the embodiments of FIGS. 2-5 may operate simultaneously in the Charge mode and the Discharge mode.

[0172] The embodiments of the electrical generation system shown in FIGS. 1a, b and c may include any one or more of the thermal batteries 3 of FIGS. 2-5.

[0173] With reference to these Figures, the energy source is solar energy 1 that, by way of example only is collected via a plurality of mirrors that reflect solar energy onto a target surface of a receiver, with the target surface comprising a plurality of photovoltaic cells, with the cells producing electricity.

[0174] The direct current electricity from the energy source 1 is transferred to a regulator/inverter 2 that ensures appropriate regulation of supply and generation of 3 phase power.

[0175] The 3-phase power from the regulator/inverter 2 is transferred to the heat conductive material (in the case of aluminium via an energy transfer unit in the form of an electric arc unit with electrodes extending into the aluminium when the thermal battery is operating in the Charge Mode.

[0176] The electric arc unit is not shown specifically in the Figures but is illustrated diagrammatically by the lead line 31 connecting together the energy source 1 and the regulator/inverter 2 and the lead line 33 connecting together the regulator/inverter 2 and the thermal battery 3.

[0177] The inductive heating unit as shown in FIGS. 2-5 is another option for heat transfer from the energy source to the thermal battery.

[0178] Heat pipes are used to transfer heat from the graphite block(s) 15 of the thermal battery 3 via the heat conductive material of the battery 3 to an electricity generation unit when the thermal battery 3 is operating in the thermal transfer mode, i.e. the Charge Mode.

[0179] The heat pipes are in heat transfer relationship with the heat conductive material fluid and, in use, evaporate a fluid in the heat tubes and absorb thermal energy as a consequence.

[0180] The resultant gas phase moves toward the cooler opposite ends of the heat pipes.

[0181] The electricity generation unit includes a heat exchanger 4 in FIGS. 1a, b and c that is in heat transfer relationship with the heat pipes at the cooler ends of the pipes. The gas phase in the heat pipes transfers heat to water flowing through the heat exchanger and generates steam.

[0182] The steam generated in the heat exchanger 4 is transferred to and drives a steam turbine generator 5 of FIGS. 1a, b and c and generates electricity.

[0183] The electricity from the steam turbine generator is transferred to end-use applications to meet power demands.

[0184] The spent steam and condensate from the steam turbine generator are collected, cooled as required, and recirculated to the heat exchanger 4.

[0185] The water used in the steam circuit is treated as required to mitigate corrosion.

[0186] The system includes monitoring and control systems to operate the system.

[0187] More particularly, the spent steam and condensate are transferred to a condenser 6 of FIGS. 1a, 1b, and 1c and condensed and cooled. Water from the condenser and make-up water from a storage tank 7 of FIGS. 1a, 1b, and 1c, and water conditioners from a water buffer tank 8 of FIGS. 1a, 1b, and 1c are transferred to the heat exchanger.

[0188] A pump 9 of FIGS. 1a, 1b, and 1c pumps water through this circuit.

[0189] The above-described thermal battery 3, in the various configurations, is a low maintenance, reliable, energy efficient and cost-effective unit that can be transported to and put into service quickly at remote locations, such as mining operations. The thermal battery is a straightforward structure. The use of a heat conductive material, that is fluid within the operating temperature range of the battery facilitates efficient heat transfer between the heat conductive material (e.g., metal or metal alloy or gas) and the heat sink material (e.g., graphite).

[0190] Many modifications may be made to the embodiment of the invention described herein without departing from the spirit and scope of the invention.

[0191] By way of example, whilst the embodiment includes graphite as the heat sink material, the invention is not so limited and extends to any suitable material with high heat capacity that remains as a solid material in the operating temperature range of the thermal battery.

[0192] By way of example, whilst the embodiment includes aluminium and CO.sub.2, N.sub.2 or Ar as examples of the heat conductive material, the invention is not so limited and extends to any suitable material with high thermal conductivity and a melting point below that of the heat sink material so that in use the heat conductive material is fluid in the operating temperature range of the battery.