Modular liquid-metal magnetohydrodynamic (LMMHD) power generation cell

• US 20050146140A1
• Filed: 01/05/2005
• Published: 07/07/2005
• Est. Priority Date: 01/05/2004
• Status: Active Grant

• Current Assignee: Raymond C. Law, Robert A. Koslover
• Original Assignee: Raymond C. Law, Robert A. Koslover
• Inventors: Koslover, Robert A., Law, Raymond C.
• Granted Patent: US 7,166,927 B2
• Time in Patent Office: Days
• US Class Current: 290/42
• CPC Class Codes: H02K 44/085 with conducting liquids
• CPC Class Codes: H02K 44/16 Constructional details of the magnetic circuits
• CPC Class Codes: H02K 44/24 by reversing the direction of fluid

Abstract

A LMMHD power generation cell, having a fluid channel in which a conductive fluid is forced to flow in response to an external force. A pair of pressure conveying members such as bellow reservoirs can be used for conveying the external force to the conductive flow. A magnetic field is established across the fluid channel by a pair of magnets. A pair of electrodes is disposed with respect to the fluid channel to collect the electric current induced by the conductive fluid flowing through the magnetic field. The magnets are selected from either permanent magnets or electromagnets. Preferably, the conductive fluid is selected from low-density, low-viscosity, high-conductivity liquid metal such as NaK-78.

Claims

1. A liquid-metal magneto-hydrodynamic power generation cell, comprising:

a fluid channel;

a conductive fluid sealed within the fluid channel and flowing along the fluid channel in response to an external force;

a pair of magnets disposed at a first pair of opposing sides of the fluid channel, each of the magnets has a tapered side surface adjacent to the fluid channel; and

a pair of electrodes disposed at a second pair of opposing sides of the fluid channel, the electrodes extending perpendicularly to a magnetic field generated by the magnets.

2. The power generation cell of claim 1, wherein the fluid channel includes two opposing ends tapered from two sides of each electrode.

3. The power generation cell of claim 1, further comprising a pair of bellow reservoirs coupled to two opposing ends of the fluid channel.

4. The power generation cell of claim 1, wherein the fluid channel is sealed within an insulating housing.

5. The power generation cell of claim 1, further comprising a pair of yoke for holding the magnets therein.

6. The power generation cell of claim 5, wherein each of the yoke includes two symmetric magnetic steel members joined with each other by a non-magnetic separator.

7. The power generation cell of claim 1, wherein the conductive liquid includes liquid metal having conductivity of about 2.63×

10⁶ S/m.

8. The power generation cell of claim 1, wherein the conductive liquid includes eutectic alloy of sodium and potassium, NaK.

9. The power generation cell of claim 1, wherein the magnets include permanent magnets.

10. The power generation cell of claim 9, wherein the magnets are fabricated from sintered NdFeB.

11. The power generation cell of claim 1, wherein the magnets include electromagnets.

12. A liquid-metal magneto-hydrodynamic power generation cell, comprising:

a fluid channel, having two opposing tapered ends;

a liquid metal flowing within the fluid channel in response to an external force;

a pair of magnets positioned with respect to the fluid channel to provide a magnetic field perpendicular to the fluid channel between the tapered ends; and

a pair of electrodes, positioned between the tapered ends for intercepting an electric current induced by flow of the liquid metal through the magnetic field.

13. The power generation cell of claim 12, further comprising a pair of pressure conveying members coupled to the tapered ends of the fluid channel.

14. The power generation cell of claim 12, further comprising a pair of yokes holding the magnets.

15. The power generation cell of claim 14, wherein each of the yoke includes a magnetic steel member and a non-magnetic gap partitioning the magnetic steel member into two symmetric parts.

16. A liquid-metal magneto-hydrodynamic power generation cell, comprising:

a fluid channel;

a liquid metal flowing within the fluid channel in response to an external force;

a pair of magnets for generating a magnetic field perpendicular to flow of the liquid metal;

a pair of electrodes for collecting an electric current induced by the liquid metal flowing through the magnets; and

a pair of yokes holding the magnets around the fluid channel, each of the yokes comprising;

a pair of symmetric magnetic steel portions; and

a non-magnetic member connecting the symmetric magnetic steel portions.

17. The power generation cell of claim 16, further comprising a pair of bellow reservoirs coupled to two opposing ends of the fluid channel for conveying the external force to the liquid metal.

18. A power generator, comprising:

an array of liquid-metal magneto-hydrodynamic power generation cells connected in series, each of the power generation cells comprising;

a fluid channel;

a pair of internal pressure conveying members coupled to two ends of the fluid channel;

a liquid metal sealed within the fluid channel, the liquid-metal flowing within the fluid channel in response to motion of the pressure conveying members;

a pair of magnets for establishing a magnetic field perpendicular to flow direction of the liquid metal;

a pair of electrodes disposed perpendicular to both the flow direction and the magnetic field;

a pair of external pressure conveying members communicating with the internal pressure conveying members at two ends of the fluid channel; and

a pair of output terminals coupled to the electrodes.

19. The generator of claim 18, wherein the internal pressure conveying members include bellow reservoirs.

20. The generator of claim 18, wherein the liquid metal includes eutectic alloy of sodium and potassium, NaK-78.

21. The generator of claim 18, wherein the magnets include electromagnets.

22. The generator of claim 18, wherein the magnets include permanent magnets.

23. The generator of claim 18, wherein the fluid channel comprises two tapered ends at two sides of the electrodes.

24. The generator of claim 18, wherein each of the magnets has a tapered side surface adjacent to the fluid channel.

25. The generator of claim 18, wherein each power generation cell further comprises a pair of yokes holding the magnets.

26. The generator of claim 25, wherein the yokes are fabricated from magnetic steel.

27. The generator of claim 26, wherein each of the yokes includes two symmetric magnetic members and a non-magnetic member connecting the symmetric magnetic members together.

28. The generator of claim 18, wherein the external pressure conveying members include:

a pair of chambers enclosing the internal conveying members therein;

hydraulic oil filled in the chambers; and

a pair of pistons connected to the chambers.

29. A method of increasing power efficiency of a liquid-metal magneto-hydrodynamic power generation cell, comprising:

providing a tapered magnetic field perpendicular to a flow of liquid metal; and

providing a pair of electrodes for collecting an electric current induced by the flow of liquid metal through the tapered magnetic field.

30. The method of claim 29, further comprising a step of tapering the flow of liquid metal at two opposing sides of the electrodes.

31. A method of suppressing magnetic saturation of a liquid-metal magneto-hydrodynamic power generation cell which comprises a fluid channel, a liquid metal flowing within the fluid channel, a pair of magnets providing a magnetic field perpendicular to the flow of the liquid metal, and a pair of magnetic yokes holding the magnets about the fluid channel, the method comprising:

using a non-magnetic material to partition each of the magnetic yokes into two symmetric magnetic portions.