Active vortex generator to improve heat transfer in heat exchangers

Patent metadata

Field	Value
Publication number	US-11525640-B2
Application number	US-202016782117-A
Country	US
Kind code	B2
Filing date	Feb 5, 2020
Priority date	Feb 14, 2019
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

An active vortex generator adapts to a flow rate of fluid through and/or a heat flux applied through a heat exchanger channel to improve the heat transfer rate of the heat exchanger. In some implementations, the movement of the active vortex generator may be induced by the fluid flow through the heat exchanger channel. In some implementations, the movement of the active vortex generator may be induced through an externally applied force on the active vortex generator. An actuated active vortex generator is particularly suited to heat exchangers with high heat flux dissipation requirements. Locating an actuated active vortex generator proximate to such high heat flux dissipation locations provides for improved heat transfer that can be activated when needed, such as upon operation of a high heat flux component.

First claim

What is claimed is:

1. A heat exchanger, comprising:
an enclosed cooling fluid channel comprising a heat transfer surface, the cooling fluid channel adapted to receive a flow of a liquid cooling fluid along a length of the cooling fluid channel;
an anchor extending across the cooling fluid channel in a direction perpendicular to the length of the cooling fluid channel and parallel to the heat transfer surface;
an active vortex generator affixed to the anchor and configured to extend in a direction parallel to the heat transfer surface; and
an actuator coupled to the anchor and configured to move the anchor along an oscillation path within the cooling fluid channel, wherein the oscillation path within the cooling fluid channel is perpendicular to the heat transfer surface and is closer to the heat transfer surface than a surface of the cooling fluid channel opposite to the heat transfer surface such that vortices generated by the active vortex generator are produced in a thermal boundary layer along the heat transfer surface,
wherein at least a portion of a length of the active vortex generator is sufficiently rigid to resist induced generation of vortices due the flow of the liquid cooling fluid, but sufficiently flexible that motion of the anchor along the oscillation path produces a vortex.

2. The heat exchanger of claim 1 , wherein the anchor is a rod, bar, tube, or beam.

3. The heat exchanger of claim 1 , wherein the active vortex generator comprises a flexible sheet of material selected from a group of flexible materials consisting of a metal plate, a polymeric plate, and a textile sheet.

4. The heat exchanger of claim 3 , wherein a leading edge of the flexible sheet of material is affixed to the anchor as a rotatable joint and a trailing edge of the flexible sheet of material is free to move within the cooling fluid channel.

5. The heat exchanger of claim 1 , wherein the active vortex generator comprises a sheet of material with a rigid portion and a flexible portion.

6. The heat exchanger of claim 5 , wherein a leading edge of the sheet of material comprises the rigid portion and a trailing edge of the sheet of material comprises the flexible portion.

7. The heat exchanger of claim 6 , wherein the leading edge of the sheet of material is affixed to the anchor as a rigid joint and the trailing edge of the sheet of material is free to move within the cooling fluid channel.

8. The heat exchanger of claim 1 , wherein the active vortex generator comprises a rigid sheet of material affixed to the anchor as a rigid joint.

9. The heat exchanger of claim 1 , wherein the active vortex generator is configured to extend in a direction counter to the flow of the liquid cooling fluid in the cooling fluid channel.

10. The heat exchanger of claim 1 , wherein the active vortex generator comprises a sheet of material with the length between 0.5-2.5 mm.

11. The heat exchanger of claim 10 , wherein a width of the sheet of material is substantially the same dimension as the length of the sheet of material.

12. The heat exchanger of claim 10 , wherein a width of the cooling fluid channel is 2-3 times the length of the sheet of material.

13. The heat exchanger of claim 10 , wherein a thickness of the sheet of material is less than 0.05 times the length of the sheet of material.

14. The heat exchanger of claim 1 , wherein the actuator is coupled to a first end of the anchor, the heat exchanger further comprising:
a second actuator coupled to a second end of the anchor and configured to move the anchor along the oscillation path.

15. The heat exchanger of claim 1 , wherein the actuator is configured to move the anchor along the oscillation path at a frequency of 0.05-0.2 seconds.

16. An active vortex generator for a heat exchanger, comprising:
an anchor coupled across an enclosed fluid channel parallel to a heat transfer surface in the fluid channel, wherein the anchor is perpendicular to a flow of a liquid cooling fluid within the fluid channel;
the active vortex generator is affixed to the anchor and extends in a direction parallel to the heat transfer surface; and
an actuator coupled to the anchor and adapted to move the anchor along an oscillation path within the flow of the liquid cooling fluid within the fluid channel, wherein the oscillation path within the fluid channel is perpendicular to the heat transfer surface and is closer to the heat transfer surface than a surface of the fluid channel opposite to the heat transfer surface such that vortices generated by the active vortex generator are produced in a thermal boundary layer along the heat transfer surface,
wherein at least a portion of a length of the active vortex generator is sufficiently rigid to resist induced generation of vortices due the flow of the liquid cooling fluid, but sufficiently flexible that motion of the anchor along the oscillation path produces a vortex.

17. The heat exchanger of claim 1 , wherein the active vortex generator is positioned proximate to a high heat flux dissipation location with two-phase heat transfer.

18. The heat exchange of claim 1 , wherein the actuator manipulates a frequency at which the anchor travels along the oscillation path to produce a desired amount of vortices.

19. The active vortex generator of claim 16 , wherein the actuator is coupled to a first end of the anchor, the active vortex generator further comprising:
a second actuator coupled to a second end of the anchor and configured to move the anchor along the oscillation path.

20. The active vortex generator of claim 16 , wherein the actuator is configured to move the anchor along the oscillation path at a frequency of 0.05-0.2 seconds.

Assignees

• Univ Florida State Res Found Inc

Inventors

• Shoele Kourosh
• Vahab Mehdi

Classifications

• F28F13/10

  by imparting a pulsating motion to the flow, e.g. by sonic vibration · CPC title

• F28F13/125 Primary

  by stirring · CPC title

• F28F13/02

  by influencing fluid boundary (boundary-layer control in general F15D) · CPC title