Systems and methods for efficient two-phase heat transfer in compressed-air energy storage systems
View Patent ↗In various embodiments, foam is compressed to store energy and/or expanded to recover energy.
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; and
expanding 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; and
forming 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.