Magnetohydrodynamic pump
A magnetohydrodynamic (MHD) device including an electrochemical cell, an aqueous liquid, and a magnet is provided. The electrochemical cell includes a first and a second electrode and an enclosed gas volume fluidly connecting the two electrodes. The first electrode generates a reaction gas at a first rate, the second electrode consumes the reaction gas at a second rate, the first rate being substantially equal to the second rate. The aqueous liquid is between the first electrode and the second electrode and includes a current having a direction. The magnet generates a magnetic field having a direction normal to the direction of the current. The MHD device produces a propulsive force having a direction simultaneously normal to the direction of the magnetic field and the direction of the current.
1 . A magnetohydrodynamic (MHD) device, the MHD device comprising:
an electrochemical cell comprising:
a first electrode configured to generate a reaction gas at a first rate, a second electrode configured to consume the reaction gas at a second rate, the first rate being substantially equal to the second rate, and
an enclosed gas volume fluidly connecting the first electrode and the second electrode;
an aqueous liquid between the first electrode and the second electrode and comprising a current having a direction; and
a magnet configured to generate a magnetic field having a direction normal to the direction of the current,
the MHD device being configured to produce a propulsive force having a direction simultaneously normal to the direction of the magnetic field and the direction of the current.
2 . The MHD device of claim 1 , wherein the aqueous liquid comprises a plurality of mobile ions.
3 . The MHD device of claim 2 , wherein the propulsive force accelerates the plurality of mobile ions.
4 . The MHD device of claim 2 , wherein the plurality of mobile ions comprises sodium and chloride.
5 . The MHD device of claim 1 , wherein at least one of the first electrode or the second electrode comprises a gas diffusion electrode.
6 . The MHD device of claim 5 , wherein the gas diffusion electrode comprises a gas permeable membrane.
7 . The MHD device of claim 6 , wherein the gas permeable membrane has pores with an average pore size from about 0.05 micrometer (μm) to about 100 μm.
8 . The MHD device of claim 6 , wherein the gas diffusion electrode further comprises a catalyst, an additive, or a combination thereof.
9 . The MHD device of claim 1 , wherein the reaction gas comprises hydrogen, the first electrode comprises a cathode configured to reduce water, and the second electrode comprises an anode configured to oxidize hydrogen.
10 . The MHD device of claim 1 , wherein
the reaction gas comprises oxygen, the first electrode comprises an anode configured to oxidize water, and the second electrode comprises a cathode configured to reduce oxygen, or
the reaction gas comprises chlorine, the first electrode comprises an anode configured to oxidize chlorine, and the second electrode comprises a cathode configured to reduce chlorine.
11 . A method of operating a magnetohydrodynamic (MHD) device,
the MHD device comprising:
an electrochemical cell comprising a first electrode, a second electrode, and an enclosed gas volume;
an aqueous liquid between the first electrode and the second electrode; and
a magnet,
the method comprising:
generating a reaction gas at a first rate on the first electrode;
consuming the reaction gas at a second rate on the second electrode, the first rate being substantially equal to the second rate;
fluidly connecting the first electrode and the second electrode via the enclosed gas volume;
generating a current having a direction in the aqueous liquid with the electrochemical cell;
generating a magnetic field having a direction normal to the direction of the current with the magnet; and
producing a propulsive force having a direction simultaneously normal to the direction of the magnetic field and the direction of the current.
12 . The method of claim 11 , wherein the reaction gas comprises hydrogen, the first electrode comprises a cathode configured to reduce water, and the second electrode comprises an anode configured to oxidize hydrogen.
13 . The method of claim 11 , wherein the electrochemical cell comprises a current density, the current density is from about 1.0 milliampere per square centimeter (mA/cm 2 ) to about 1000 mA/cm 2 .
14 . The method of claim 11 , wherein the propulsive force is produced with a minimal amount of bubbles produced in the aqueous liquid.
15 . A method of operating a water pump,
the water pump comprising:
the MHD device of claim 1 ; and
the aqueous liquid, and
the method comprising:
applying a current density across the electrochemical cell; and
accelerating the aqueous liquid.
16 . The method of claim 15 , wherein the reaction gas comprises hydrogen, the first electrode comprises a cathode configured to reduce water, and the second electrode comprises an anode configured to oxidize hydrogen.
17 . The method of claim 15 , wherein the method accelerates the aqueous liquid with a minimal amount of bubbles produced in the aqueous liquid.
18 . A propulsion system for a sea ship, the propulsion system comprising the sea ship connected to the MHD device of claim 1 , wherein the aqueous liquid is seawater and the system is configured to apply a current density across the electrochemical cell and propel the sea ship through the seawater.
19 . The propulsion system of claim 18 , wherein the reaction gas comprises hydrogen, the first electrode comprises a cathode configured to reduce water, and the second electrode comprises an anode configured to oxidize hydrogen.
20 . The propulsion system of claim 18 , wherein the system is configured to propel the sea ship through the seawater with a minimal amount of bubbles produced in the seawater.
21 . The propulsion system of claim 18 , wherein the sea ship comprises an unmanned underwater vehicle.
22 . The propulsion system of claim 21 , wherein the unmanned underwater vehicle comprises an autonomous system.