Systems and methods of using phase change material in power plants
Phase change material modules for use in a heat exchanger are described. The phase change material module comprises two or more set of a plurality of substantially aligned hollow structures arranged to form a porous structure. A phase change material capable of undergoing a phase change as a result of heat exchange between it and a fluid is housed within the hollow tubes. Also described is a phase change material module with hollow tubes having a cross-sectional area through the phase change material selected from elliptical, rectangular, stadium-shaped, teardrop-shaped, airfoil-shaped, rounded rectangle and ovoid. A heat exchanger comprising a plurality of the phase change material modules, a first fluid inlet and outlet, and a second fluid inlet and outlet, wherein the phase change material modules are repeated circulated from alignment with the first fluid inlet and the second fluid inlet is also described.
1. A heat exchanger for cooling a fluid comprising:
a plurality of phase change material modules mounted for rotation about a central axis to form a porous structure having a porosity of from 94% to 98%, each said phase change material module including a plurality of hollow structures and a phase change material housed within the hollow structures;
a first fluid inlet positioned to direct the fluid through the porous structure for contact between the first fluid and an outer surface of the hollow structures;
a first fluid outlet for removing the first fluid from the heat exchanger and located to receive the first fluid after contact with the hollow structures;
a second fluid inlet positioned to direct a second fluid through the porous structure for contact between the second fluid and the outer surface of the hollow structures; and
a second fluid outlet for removing the second fluid from the heat exchanger and located to receive the second fluid after contact with the hollow structures;
wherein rotation of the plurality of phase change material modules repeatedly circulates the porous structure of the modules into alignment with the first fluid inlet and the second fluid inlet, and the phase change material is selected to undergo a phase change as a result of heat exchange with each of the first and second fluids, and the outer surfaces of the hollow structures are formed from a hydrophobic material.
2. The heat exchanger of claim 1 , wherein said phase change material is selected from the group consisting of paraffinic hydrocarbons and fatty acids.
3. The heat exchanger of claim 1 , comprising at least two sets of hollow structures in each said phase change material module and wherein a longitudinal axis of each hollow tube of one said set is substantially aligned in an intended fluid flow direction of the first fluid.
4. The heat exchanger of claim 3 , wherein a distance between said hollow structures of one said set, as measured in a direction substantially parallel to the intended fluid flow direction of the first fluid, is from about 1 to about 5 times a largest distance across one said hollow structure, as measured in the direction substantially parallel to the intended fluid flow direction of the first fluid and a distance between said hollow structures of another said set, as measured in a direction substantially perpendicular to an intended fluid flow direction of the first fluid is from about 4 to about 16 times a largest distance across one said hollow structure in a direction substantially parallel to the intended fluid flow direction of the first fluid.
5. The heat exchanger of claim 1 , wherein the hollow structures have a length of a cross-section of the hollow structures that is at least twice as long as a width of the same cross-section of the hollow structure.
6. The heat exchanger of claim 1 , further comprising a drainage section operatively configured to recapture some of the first fluid and located between the first fluid inlet and the second fluid outlet, based on a direction of the rotation of the plurality of phase change material modules and including a device for providing an array of pressurized air jets directed at said hollow structures.
7. The heat exchanger of claim 1 , wherein the first fluid inlet is fluidly connected to a supply of liquid and the second fluid inlet is fluidly connected to a supply of air and the phase change material freezes at a temperature above a temperature of the air and below a temperature of the liquid.
8. The heat exchanger of claim 1 , wherein a flow direction of the first fluid inlet is substantially opposite a flow direction of the second fluid inlet.
9. The heat exchanger of claim 1 , wherein said hollow structures have a cross-sectional area through said phase change material selected from the group consisting of elliptical, rectangular, stadium-shaped, teardrop-shaped, airfoil shaped, rounded rectangular, and ovoid.
10. The heat exchanger of claim 1 , wherein each of said hollow structures includes a plurality of partitions inside the hollow structure to increase rigidity of the hollow structure.
11. A power plant cooling system or a data center cooling system comprising a plurality of the heat exchangers as claimed in claim 1 .
12. The heat exchanger of claim 1 , further comprising a drainage section operatively configured to recapture some of the first fluid and located between the first fluid inlet and the second fluid outlet, based on a direction of the rotation of the plurality of phase change material modules.
13. The heat exchanger of claim 3 , wherein a longitudinal axis of each of the hollow structures in the second set of hollow structures is substantially aligned perpendicular to an intended fluid flow direction of the first fluid.
14. The heat exchanger of claim 1 , wherein the phase change material is selected to undergo a phase change between a liquid phase and a solid phase, and an additional liquid is also located within each said hollow tube to form a slurry of said solid phase of the phase change material in said additional liquid.