SYSTEMS AND METHODS FOR EFFICIENT TWO-PHASE HEAT TRANSFER IN COMPRESSED-AIR ENERGY STORAGE SYSTEMS
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 .- 451 . (canceled)