초록

In various embodiments, foam is compressed to store energy and/or expanded to recover energy.

대표청구항 ▼

1. A method of recovering energy, the method comprising: transferring a first foam to a first cylinder assembly, the first foam having a first foam expansion ratio;expanding the first foam in the first cylinder assembly, thereby recovering energy therefrom;thereafter, transferring a second foam to a

1. A method of recovering energy, the method comprising: transferring a first foam to a first cylinder assembly, the first foam having a first foam expansion ratio;expanding the first foam in the first cylinder assembly, thereby recovering energy therefrom;thereafter, transferring a second foam to a second cylinder assembly different from the first cylinder assembly, the second foam having a second foam expansion ratio larger than the first foam expansion ratio; andexpanding the second foam in the second cylinder assembly, thereby recovering energy therefrom. 2. The method of claim 1, further comprising exhausting the expanded second foam from the second cylinder assembly. 3. The method of claim 2, wherein at least a gaseous portion of the expanded second foam is exhausted to ambient atmosphere. 4. The method of claim 1, wherein (i) after expanding the first foam, the expanded first foam is exhausted from the first cylinder assembly and (ii) the second foam comprises at least a portion of the expanded first foam. 5. The method of claim 4, wherein the expanded first foam is exhausted into a foam vessel, and further comprising circulating heat-transfer liquid in the foam vessel to form the second foam. 6. The method of claim 1, further comprising: after expanding the first foam, separating at least a portion of the expanded first foam into gaseous and liquid components; andforming the second foam by introducing heat-transfer liquid into the gaseous component of the expanded first foam. 7. The method of claim 6, wherein the at least a portion of the expanded first foam is separated via at least one of mechanical separation or application of ultrasound energy. 8. The method of claim 7, wherein the at least a portion of the expanded first foam is separated via mechanical separation by at least one of a blade, a shear, a baffle, or a centrifuge. 9. The method of claim 6, further comprising storing the liquid component of the expanded first foam. 10. The method of claim 1, wherein a mass ratio of the first foam is approximately equal to a mass ratio of the second foam. 11. The method of claim 1, further comprising altering at least one of an average cell size or a uniformity of cell size of the first foam before expanding the first foam. 12. The method of claim 1, further comprising altering at least one of an average cell size or a uniformity of cell size of the second foam before expanding the second foam. 13. The method of claim 1, wherein a foam mass ratio of the first foam is selected from the range of 1 to 4. 14. The method of claim 1, wherein a foam mass ratio of the second foam is selected from the range of 1 to 4. 15. The method of claim 1, wherein the first foam is expanded substantially isothermally and the second foam is expanded substantially isothermally. 16. The method of claim 1, further comprising forming the first foam by mingling heat-transfer liquid and compressed gas. 17. The method of claim 16, further comprising controlling a void fraction of the first foam by controlling a rate of transfer of heat-transfer liquid into the compressed gas. 18. The method of claim 17, further comprising sensing at least one of a pressure or a temperature within the first cylinder assembly, wherein the rate of transfer is controlled in response thereto. 19. The method of claim 1, wherein expanding the first foam and expanding the second foam both drive a crankshaft mechanically coupled to the first and second cylinder assemblies. 20. The method of claim 1, further comprising, after expanding the second foam, separating at least a portion of the expanded second foam into gaseous and liquid components. 21. The method of claim 20, wherein the at least a portion of the expanded second foam is separated via at least one of mechanical separation or application of ultrasound energy. 22. The method of claim 20, wherein the at least a portion of the expanded second foam is separated via mechanical separation by at least one of a blade, a shear, a baffle, or a centrifuge. 23. The method of claim 20, further comprising storing the liquid component of the expanded second foam. 24. The method of claim 20, further comprising exhausting the gaseous component of the expanded second foam to ambient atmosphere. 25. The method of claim 19, wherein driving the crankshaft produces electrical current via an electric generator mechanically coupled to the crankshaft. 26. The method of claim 25, further comprising converting at least a portion of the electrical current from alternating-current to direct-current. 27. The method of claim 16, wherein the heat-transfer liquid comprises water containing at least one foaming additive. 28. The method of claim 27, wherein the at least one foaming additive comprises at least one of a mineral oil, a glycol, a sulfonate, a fluorosurfactant, or an ethanolamine. 29. The method of claim 16, wherein forming the first foam comprises spraying the heat-transfer fluid on a screen. 30. The method of claim 1, wherein (i) the second foam comprises water containing at least one foaming additive, and (ii) the at least one foaming additive comprises at least one of a mineral oil, a glycol, a sulfonate, a fluorosurfactant, or an ethanolamine.