Method and system for generating a gas mixture

Abstract

A method and system for generating a gas mixture, such as a hydrogen-oxygen or hydrogen-air gas mixture, can be used for topical or inhalation therapeutic applications. In one embodiment, the system can include a water electrolysis device combined with an oxygen humidifier reservoir so that hydrogen generated at the cathode of the water electrolysis device mixes directly with oxygen gas introduced into the oxygen humidifier reservoir, for example, by sparging. In another embodiment, the cathode manifold of the water electrolysis device can be plumbed in series with a pump and an oxygen humidifier reservoir so that hydrogen-laden water mixes with oxygen delivered to the oxygen humidifier reservoir, for example, by sparging. In an exemplary application, the system can be integrated into a ventilator circuit to provide a breathing gas mixture containing hydrogen to treat ischemia / reperfusion injury in brain tissue.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 63 / 439,788, filed January 18, 2023, by inventors Simon Gregory Stone et al., the disclosure of which is incorporated herein by reference.

[0002] The present invention relates generally to methods and systems for generating gas mixtures, and more particularly to novel methods and systems for generating hydrogen-containing gas mixtures, such as gas mixtures comprising oxygen gas and hydrogen gas, that can be used to treat certain physical conditions, including, for example, but not limited to, ischemia-reperfusion injury, particularly to brain tissue. [Background technology]

[0003] Many diseases and traumas to the human body involve periods of ischemia, during which blood flow and, therefore, oxygen delivery to a body part is reduced. As can be appreciated, such periods of reduced blood flow and oxygen delivery can be harmful to the affected area of ​​the body. Unfortunately, the resumption of more normal blood flow after a period of ischemia, i.e., reperfusion, can also present a risk of injury to the affected area. Such injury, often referred to as ischemia / reperfusion injury (IRI), is due, at least in part, to the generation of reactive oxygen species produced during reperfusion. These reactive oxygen species can cause chemical damage to DNA and, in some cases, trigger a cascade of cellular processes that can lead to apoptosis. One potential way to limit damage in these situations is to administer one or more antioxidants that rapidly react with the reactive oxygen species produced during reperfusion. One such antioxidant identified for this purpose is molecular hydrogen, which can be administered to patients via various modes of administration, including inhalation. Numerous publications have positively reported on the safety of hydrogen inhalation (and other means of hydrogen administration) and its effectiveness for various indications. See, for example, Non-Patent Document 1 and Non-Patent Document 2. Both of these documents are incorporated herein by reference.

[0004] Numerous commercial products outside the United States produce hydrogen-oxygen gas mixtures for inhalation. Some of these products are marketed as suitable for treating various illnesses, while others are marketed as suitable for preventing specific diseases or disorders. Unfortunately, however, in many cases, these products produce hydrogen-oxygen gas mixtures in a ratio resulting from direct water electrolysis, i.e., 2H2 / 1O2. Such 2:1 hydrogen-oxygen mixtures are flammable and explosive and therefore pose unacceptable risks in medical trauma, intensive care, and emergency response situations. As a result, products that produce such gas mixtures are generally not suitable for use as medical devices in the United States, Europe, and many other countries. On the other hand, more dilute hydrogen-oxygen mixtures, such as 2-4% H2 by volume in oxygen, are non-flammable and therefore inherently safe, and recently published studies have demonstrated clinical safety and preclinical efficacy. See, for example, "Hydrogen-Oxygen Mixtures," IEEE Transactions on Clinical Chemistry, Vol. 1, No. 1, pp. 111-114, 2002, incorporated herein by reference.

[0005] In view of the above, there is a clear need for methods and systems that can be used to safely generate gas mixtures containing hydrogen gas, and there is also a clear need for methods and systems that can be used to administer such hydrogen-containing gas mixtures to people, for example, by inhalation, for therapeutic and / or other purposes.

[0006] Additional references that may be of interest include the following patent documents: U.S. Patent No. 6,202,228 to inventor Lin, issued on August 16, 2022; U.S. Patent No. 6,202,117 to inventor Lin, issued on August 31, 2021; U.S. Patent No. 6,202,117 to inventor Lin, issued on April 23, 2019; U.S. Patent No. 6,202,215 to inventor Ohta et al., issued on June 9, 2015; U.S. Patent No. 6,202,215 to inventor Satoh et al., published on November 26, 2020; U.S. Patent No. 6,202,215 to inventor Hata et al., published on October 18, 2018; U.S. Patent No. 6,202,215 to inventor Satoh et al., published on October 15, 2015; U.S. Patent No. 6,202,215 to inventor Satoh et al., issued on June 4, 2020; U.S. Patent No. 6,202,215 to inventor Satoh et al., published on January 7, 2016; and U.S. Patent No. 6,202,215 to inventor Satoh et al., published on May 25, 2023, all of which are incorporated herein by reference. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide a novel method and system for generating a gas mixture.

[0008] It is also an object of the present invention to provide such a method and system that overcomes at least some of the problems of existing methods and systems for producing gas mixtures. [Means for solving the problem]

[0009] Thus, according to one aspect of the present invention, there is provided a system for generating a gas mixture comprising: (a) a water reservoir having a predetermined amount of water, a first gas inlet through which a first delivery gas is delivered to the predetermined amount of water, and a gas outlet through which the gas mixture exits the water reservoir; (b) a water electrolysis device connected to the water reservoir to receive water from the predetermined amount of water and to deliver a first product gas that is added to the predetermined amount of water; and (c) the first delivery gas and the first product gas mix in the predetermined amount of water to form a gas mixture that exits the water reservoir through the gas outlet.

[0010] In more detailed features of the invention, the first delivery gas may be oxygen and the first product gas may be hydrogen.

[0011] In more detailed features of the invention, the first delivery gas may be one of air and oxygen-enriched air, and the first product gas may be hydrogen.

[0012] In more detailed features of the invention, at least a portion of the water electrolysis device may be disposed in a volume of water within a water reservoir.

[0013] In a more detailed feature of the invention, the first product gas may be hydrogen, and the water electrolysis device may include a cathode, which may be disposed in a predetermined amount of water in a water reservoir to directly deliver hydrogen into the predetermined amount of water.

[0014] In more detailed features of the invention, the water electrolysis device may further include an anode for delivering the second product gas, and the system may further include a first fluid conduit for discharging the second product gas.

[0015] In more detailed features of the invention, the water electrolysis device may further include an anode for delivering the second product gas, and the system may further include a second fluid conduit for transferring the second product gas to the gas mixture at a location external to the water reservoir.

[0016] In a more detailed aspect of the invention, the water electrolysis device may be located entirely outside the water reservoir.

[0017] In a more detailed feature of the invention, the system may further include a pump, which may be fluidly connected between the water reservoir and the water electrolysis device for pumping water from the water reservoir to the water electrolysis device.

[0018] In a more detailed aspect of the invention, the pump may be a cathode feed pump.

[0019] In a more detailed aspect of the invention, the water electrolysis device may consist of a single electrolysis cell.

[0020] In more detailed features of the invention, the water electrolysis device may comprise a bipolar stack of electrolysis cells.

[0021] In a more detailed feature of the invention, the system may further comprise an air bubble remover, which may be disposed in series between the water reservoir and the pump.

[0022] In a more detailed feature of the present invention, the water electrolysis device may include a polymer electrolyte membrane, an anode operably coupled to one side of the polymer electrolyte membrane, and a cathode operably coupled to an opposite side of the polymer electrolyte membrane.

[0023] In more detailed features of the invention, the water reservoir may further comprise a second gas inlet capable of delivering a second delivery gas to the volume of water.

[0024] In more detailed features of the invention, the second delivery gas may include at least one therapeutic gas selected from the group consisting of anesthesia and nitric oxide.

[0025] In more detailed aspects of the invention, the gas mixture may include hydrogen and oxygen, and the hydrogen concentration may not exceed 4% by volume.

[0026] In more detailed features of the invention, the system may further include a power supply for supplying power to the water electrolysis device, and a controller for controlling the output of the power supply.

[0027] In a more detailed feature of the invention, the system may further include a gas flow meter for measuring the gas flow rate of the first delivery gas relative to the predetermined amount of water, and the gas flow meter may be operably connected to the controller.

[0028] In more detailed features of the invention, the system may further comprise a hydrogen gas sensor for measuring the hydrogen concentration of the gas mixture, and the hydrogen gas sensor may be operably connected to the controller.

[0029] According to another aspect of the present invention, A ventilator system is provided, comprising: (a) an oxygen-containing gas source that supplies a predetermined amount of oxygen-containing gas; (b) a ventilator operably connected to the oxygen-containing gas source to receive the oxygen-containing gas and to deliver the oxygen-containing gas; (c) a system for generating a gas mixture as described above, wherein the oxygen-containing gas is a first delivery gas and the first product gas is hydrogen gas, such that the gas mixture comprises oxygen and hydrogen; and (d) a patient ventilation interface device operably coupled to the ventilator and the system for generating a gas mixture such that the gas mixture is administered to a patient by inhalation.

[0030] According to yet another aspect of the present invention, there is provided a method for generating a gas mixture, the method comprising: (a) providing a water reservoir, the water reservoir comprising a predetermined amount of water, a first gas inlet through which a first delivery gas is delivered to the predetermined amount of water, and a gas outlet through which the gas mixture exits the water reservoir; (b) providing a water electrolysis device, the water electrolysis device connected to the water reservoir for receiving water from the predetermined amount of water and delivering a first product gas to be added to the predetermined amount of water; (c) delivering the first delivery gas to the predetermined amount of water; and (d) operating the water electrolysis device to generate a first product gas; and (e) whereby the first delivery gas and the first product gas mix in the predetermined amount of water to form a gas mixture that exits the water reservoir through the gas outlet.

[0031] For purposes of this specification and claims, various relative terms such as "top," "bottom," "proximal," "distal," "upper," "lower," "front," and "rear" may be used to describe the invention when positioned or viewed in a given orientation. It is understood that changing the orientation of the invention may require that certain relative terms be adjusted accordingly.

[0032] Additional objects, as well as aspects, features, and advantages of the present invention will be set forth in part in the following description, and in part will be obvious from the description, or may be learned by practice of the invention. Reference is made in this specification to the accompanying drawings, which form a part hereof, and which show, by way of illustration, various embodiments for carrying out the invention. The embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it should be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. [Brief explanation of the drawings]

[0033] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are not necessarily drawn to scale and certain components may have smaller and / or larger dimensions for illustrative purposes. In the drawings, like reference numerals represent like parts. [Figure 1] 1 is a simplified schematic diagram of a first embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention. [Figure 2] FIG. 2 is a simplified cross-sectional view of the water electrolysis device shown in FIG. 1. [Figure 3]2 is a partially exploded perspective view of one embodiment of the combined water reservoir and water electrolysis device shown in FIG. 1. FIG. [Figure 4] 1 is a simplified schematic diagram of a second embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention. [Figure 5] 1 is a simplified schematic diagram of a third embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention. [Figure 6] 1 is a simplified schematic diagram of a fourth embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention. [Figure 7] 10 is a simplified schematic diagram of a fifth embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention. [Figure 8] 10 is a simplified schematic diagram of a sixth embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention. [Figure 9] 1 is a schematic diagram of a first embodiment of a baffled fluid conduit constructed in accordance with the present invention; [Figure 10] 1 is a simplified schematic diagram of a first embodiment of a ventilator circuit constructed in accordance with the present invention; [Figure 11] FIG. 2 is a simplified schematic diagram of a second embodiment of a ventilator circuit constructed in accordance with the present invention. [Figure 12] 1 is a graph showing the change over time in hydrogen concentration, oxygen flow rate, and cell current during constant current electrolysis of water using the configuration described in Example 1. [Figure 13] 1 is a graph showing the measured hydrogen concentration at the reservoir outlet during steady state electrolysis at 2.7 A and during sparging oxygen delivery of 1.0 SLPM to the electrolyzer reservoir in the configuration of Example 1. [Figure 14] 1 is a graph plotting polarization of the configuration described in Example 1 during operation. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention relates to novel methods and systems for generating gas mixtures. Such gas mixtures may be hydrogen-containing gas mixtures, such as, but not limited to, gas mixtures comprising hydrogen gas and oxygen gas, or gas mixtures comprising hydrogen gas and air. Such gas mixtures may be suitable for administration for therapeutic and / or prophylactic medical or health purposes, e.g., administration by inhalation and / or administration by one or more other modes of administration (e.g., topical administration). For example, such gas mixtures may be administered by inhalation to individuals suffering from ischemia / reperfusion injury of brain tissue or other tissues to reduce the effects of such injury. Such administration by inhalation may be achieved, for example, by incorporating a gas mixture generation system into a respiratory or breathing apparatus, which may further include, for example, a ventilator and mask, or a breathing tube.

[0035] More specifically, according to at least one embodiment, oxygen gas from a medical source (i.e., supply oxygen or "delivery gas") can be mixed with hydrogen (i.e., "product gas") produced by electrolysis, preferably by electrolysis of water. The supply oxygen can be an oxygen-rich stream composed of approximately 21-100 volume percent oxygen, with the remainder being nitrogen, although the supply oxygen can also include other therapeutic gases or vapors, or inert gases or vapors. In at least one embodiment, the electrolysis can be performed using a proton exchange membrane (PEM) water electrolyzer, which can include two catalyzed electrode systems (electrocatalytic films) separated by an ion-conducting proton exchange membrane. Using direct current, the aforementioned PEM water electrolyzer can electrolytically produce high-purity oxygen and hydrogen gas as separate product streams whose separation is substantially maintained by the ion-conducting proton exchange membrane. Conductive components and seals may surround the electrode system to allow electricity to be conducted through the cell with low ohmic resistance, and fluids (liquids and gases) may be appropriately directed in and out across the electrocatalyst surfaces, across the proton exchange membrane, or to the surrounding environment without leakage. Hydrogen may be produced at the electrolyzer cathode, which may be immersed in a suitable type of water (e.g., sterile deionized water), and such hydrogen may be present in a dissolved state and / or in entrained gas bubbles. Small amounts of electrolysis oxygen may be produced by the electrolyzer, which may be conveniently vented or optionally included in the outlet stream of the water reservoir. Mixing of the produced hydrogen with the supply oxygen can be achieved in both the liquid and gas phases in a water reservoir (which may be similar in many respects to ventilator humidifiers used to humidify oxygen), such as a ventilator humidifier unit of the type commercially available as the Medline Hudson RCI Bubble Humidifier (Medline Industries, LP, Uxbridge, MA). According to this mixing technique, a supply oxygen bulb, which may be generated, for example, by a sparger, can be combined and mixed with an electrolytically generated hydrogen bulb, and the dissolved gases can also equilibrate at each bulb-water interface.This rapid mixing method with fine gas bubbles can reduce the rate (in time and space) of gas mixtures exceeding 4% H by volume (i.e., the lower flammable limit). Furthermore, the mixing is surrounded by water, minimizing the probability of ignition in the mixing region. This method can safely produce an outlet stream of any concentration of hydrogen less than 4% by volume in air or oxygen.

[0036] In at least one embodiment, the electrolyzer may be of a type other than a PEM-type electrolyzer. For example, the electrolyzer may be a liquid electrolyzer of the type in which an anode and cathode, of any of a variety of shapes known in the art, may be immersed in a liquid water reservoir further containing sufficient electrolyte to complete the circuit, which results in water electrolysis with hydrogen at the cathode and oxygen at the anode bubbling into the reservoir. In such an embodiment, a supply of oxygen may be added to the reservoir, for example by sparging, to produce a desired mixture of oxygen and hydrogen gases.

[0037] In at least one embodiment, the system may also include a controller for controlling the electrolysis rate to produce a safe hydrogen-oxygen mixture composition. Such a controller may set the electrolysis rate (applied direct current) based on the input oxygen flow rate and the desired hydrogen concentration. The current set point may be calculated from a modification of Faraday's law, which may define the following pseudo-open loop control scheme: i=n×F×f hyd / V m (Formula 1) where i is the current set point (amperes), n is the number of electrons transferred in the hydrogen evolution reaction (2 electrons per molecule of hydrogen gas), and F is Faraday's constant (96485 A-s / mol e - ) and f hyd is the desired hydrogen flow rate (cm 3 / s) and V m is the molar volume (24100 cm) from the ideal gas law 3 / mol gas). The desired hydrogen flow rate can be calculated from the oxygen flow rate and the desired hydrogen concentration as follows: f hyd =f oxy / [(1 / X H2 )-1] (Formula 2) In the formula, f oxy is the oxygen flow rate, and X H2 is the desired hydrogen concentration.

[0038] In the aforementioned embodiment, only one sensor (for the oxygen flow rate) may be required, but errors in the flow controller's function or incomplete oxygen delivery to the sparger may result in the output hydrogen concentration exceeding the flammability limit. To mitigate this risk, a closed-loop approach may be utilized that operates to control the desired hydrogen concentration at a target level via an outlet hydrogen sensor. In such an embodiment, a proportional-integral-derivative control algorithm may be tuned to accurately and responsively manage the output hydrogen concentration within narrow setpoint limits. Other suitable control algorithms may also be applied. The system may also include a power supply, which may be a wall AC current converted to DC current or a DC power source. The voltage for electrolysis is preferably provided at 1.3 V or higher, and the current is preferably supplied at the level of the desired hydrogen production rate described above.

[0039] In at least one embodiment, the system may include a water reservoir similar in many respects to humidifier reservoirs of the type used in commercial ventilators. Such a water reservoir may be heated to approximately 35°C to 37°C to obtain the desired humidity level for inhalation. To further suppress the flame, a high surface area metal propagation layer (sometimes referred to as a "flame arrestor") may be included within the reservoir or within the gas outlet exiting the reservoir to arrest flame front movement through temperature regulation.

[0040] In at least one embodiment, the system may include a water electrolysis device integrated with a water reservoir similar in many respects to a humidifier reservoir in a ventilation system. In such an embodiment, hydrogen produced at the cathode of the water electrolysis device may be available at the bottom of the water reservoir, where the water electrolysis device may be incorporated. The hydrogen-oxygen mixing rate within the water reservoir may be determined by the convective properties of two-phase fluids in a bubbly flow regime. Convection in this case may be dominated by gas buoyancy during simultaneous hydrogen generation and oxygen sparging. Gas sparging (oxygen, hydrogen, or other gas) may be achieved by any method known in the art, such as through fritted or porous ceramics, metals, glasses, or polymers. Hydrogen sparging may also be achieved by microbubble formation spontaneously generated directly within the water reservoir at the cathode of the electrolysis device. Gas mixing within the water reservoir may include one or more mechanisms, or a combination of these mechanisms, including gas-phase gas bubbles combining with oxygen bubbles, hydrogen bubbles, or any combination of mixed bubbles combined with any of these bubble types. Alternatively or additionally, the water reservoir may be convectively agitated or mixed by any mechanism known in the art to aid mixing. Other mechanisms may include dissolution of either or both gases into the soluble phase, mixing of those dissolved molecules, and the dissolved gas returning to the gas phase and combining with the gas in the gas-phase bubbles. Multiple gas bubbles may exit the liquid phase of the water reservoir, merge in the gaseous headspace of the water reservoir, and exit the water reservoir through an outlet conduit. The geometry or material of the water reservoir may be designed to enhance mixing, gas solubility, or bubble combination in the liquid phase or bubble recombination in the headspace. The outlet conduit may be designed to prevent liquid-phase material from exiting the water reservoir by using a vapor-phase permeable material (e.g., GORE-TEX® expanded polytetrafluoroethylene (WL Gore & Associates, Inc., Newark, DE)) or other porous material.The outlet conduit may include alternating baffle methods to capture liquid and facilitate its return to the water reservoir, or other methods to prevent stormwater runoff, such as those disclosed in U.S. Patent Application Publication No. 2022 / 0168533, published June 2, 2022, by inventors Malouf et al., which is incorporated herein by reference.

[0041] Alternatively, in at least one embodiment, the same current control approach described above may be utilized, but hydrogen-oxygen mixing may occur with a predetermined recirculating water flow maintained by a pump from a water reservoir through the electrolyzer cathode (where oxygen may be reintroduced by sparging). While some bubbly flow characteristics may still be present in this system, the pumping action may further promote convection and allow for faster mixing. This configuration may be particularly promising for larger-scale therapeutic applications because the electrolyzer may be configured as a bipolar stack, and as a result, its gas output may be increased by the number of cells in the stack with a linear increase in applied voltage. Stacked bipolar cells generally offer the best mode for increasing power output due to minimal increase in electrolyzer volume and cost and a slight increase in power supply capability, whereas power supply and current distribution in electrochemical systems can become substantially more expensive when power is scaled with a single electrode area. The water flow in this configuration may be directed to a cathode manifold, as opposed to the anode supply method typical of commercial water electrolyzers. Thus, there may be current limitations that must be avoided due to the need for water on the anode. Water must diffuse from the cathode across the membrane to the anode to maintain electrolysis rates, and this diffusion may compete with the electroosmotic resistance of water from the anode to the cathode, a quasi-convective process. Nevertheless, commercial membranes at or near room temperature can achieve currents of 500 mA / cm. 2 The current density for electrocatalyst areas above 0.1 can be maintained stably at steady state, i.e., without voltage rise.

[0042] In at least one embodiment, the electrolytic current path may be incorporated directly into the water reservoir volume, producing separated or mixed hydrogen and oxygen gas streams therein. Catalyzed electrodes may be immersed in the aqueous electrolyte solution, and the medical oxygen supply may be sparged into the water volume below the electrodes to ensure hydrogen dilution. The electrolyte may consist of or include a salt (e.g., sodium sulfate), an acid (e.g., sulfuric acid), a base (e.g., potassium hydroxide), or a mixture thereof, and the aqueous electrolyte solution may be of sufficient composition and concentration to ensure that electrical conductivity, gas purity, and oxygen humidity requirements are met. One or both of the electrodes may optionally be integrated into the water reservoir wall.

[0043] In at least one embodiment, the system of the present invention can be used as a subsystem of a respiration or ventilation circuit for natural or assisted breathing in humans and / or animals. More broadly, the gas mixtures generated using the present invention can be used in a variety of human, veterinary, life science, and / or industrial applications. For example, the system can be used in a variety of life science environments where living cells can benefit from specific hydrogen-containing gas mixtures. More specifically, the system of the present invention can be used as a subsystem within a humidified cell culture incubator, for example, to add hydrogen to standard or non-standard mixtures of oxygen, carbon dioxide, and vapor-phase water. The system of the present invention can also be used as a subsystem to generate a mixture of hydrogen and oxygen for a pressurized bottled gas mixture, where humidity can be maintained or removed by various dryers known in the art. The system of the present invention can also be used as a subsystem of a veterinary cage system, where a small space (e.g., an animal's cage) can have a modified atmosphere containing a mixture of hydrogen and oxygen, with or without additional gases.

[0044] 1, there is shown a simplified schematic diagram of a first embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention and generally designated by the reference numeral 11. Details of system 11 that are described elsewhere in this application or that are not important to an understanding of the present invention may be omitted from FIG. 1 or the accompanying description herein, or may be shown in FIG. 1 and / or described in a simplified manner herein.

[0045] For example, a system 11 that can be used to generate a gas mixture containing hydrogen gas and oxygen gas can include a fluid conduit 13. The fluid conduit 13, which can consist of or comprise a tube or other structure suitable for transporting one or more fluids in an axial direction, can have an inlet end and an outlet end. The inlet end can be fluidly connected to the outlet of an oxygen-containing gas source. The oxygen-containing gas source can be any one or more of a variety of oxygen-containing gas sources and can consist of or comprise one or more conventional gas sources containing oxygen gas, such as, but not limited to, pure oxygen, air, or oxygen-enriched air. For example, the oxygen-containing gas source can include a ventilator that is in turn connected to the outlet of an oxygen gas source, an air source, or an oxygen-enriched air source. Alternatively, the oxygen-containing gas source may comprise one or more gas tanks containing pure oxygen gas and / or one or more gas tanks containing a mixture of oxygen gas and one or more additional gases, which may comprise, for example, one or more inert gases such as nitrogen gas and / or one or more therapeutic gases such as anesthesia. Alternatively, the oxygen-containing gas source may itself comprise a humidifier connected to the outlet of the above-mentioned ventilator or the above-mentioned one or more gas tanks.

[0046] System 11 may further include a gas flow meter 19, and the outlet end of fluid conduit 13 may be fluidly connected to the inlet of gas flow meter 19. Gas flow meter 19, which may be conventional, may be used to directly or indirectly measure the amount of oxygen gas being introduced into system 11. In this embodiment, an appropriate amount of hydrogen gas may be produced by system 11 and mixed with said measured amount of oxygen gas, as described further below.

[0047] System 11 may further include a controller 21, which may be conventional. Information collected by gas flow meter 19 may be transmitted to controller 21 through an electrical conduit 23, which may comprise conductive wire or a similarly suitable structure. Electrical conduit 23 may be electrically connected to gas flow meter 19 at a first end and to controller 21 at a second end. Controller 21 may also be electrically connected to power source 25, which may be, for example, a DC power source, via electrical conduit 27, which may comprise conductive wire or a similarly suitable structure. Electrical conduit 27 may be connected to controller 21 at a first end and to power source 25 at a second end. In this embodiment, controller 21 may be used to control the current output from power source 25 and, as will become apparent below, the amount of hydrogen produced by system 11 (there is an approximately linear relationship between current and the amount of hydrogen gas produced). Although not shown, controller 21 may include its own power source or derive power from power source 25 through suitable electrical conduits.

[0048] System 11 may further include a water reservoir 29. The water reservoir 29, which may be similar in many respects to a conventional humidifier of the type found in ventilator circuits, may comprise a container configured to receive a predetermined amount of water (a predetermined amount of water not shown in FIG. 1 ). The container may include a first inlet 31 and a first outlet 33. The first inlet 31 may be fluidly connected to the outlet of gas flow meter 19 via a fluid conduit 35, which may consist of or comprise a tube or other structure suitable for transporting one or more fluids axially therethrough. Thus, in this embodiment, oxygen-containing gas passing through gas flow meter 19 may be introduced into the water reservoir 29 through the first inlet 31.

[0049] While the first inlet 31 is shown in FIG. 1 as being located at the top of the water reservoir 29, it should be understood that the water reservoir 29 is not typically filled to capacity. Thus, the first inlet 31 may be located in the water reservoir 29 at a position below the water level of the predetermined amount of water within the water reservoir 29. Alternatively, the first inlet 31 may be located at the top of the water reservoir 29, but an inlet tube may be inserted through the first inlet 31 to transport the oxygen-containing gas to a point below the water level of the water reservoir 29. In this embodiment, the oxygen-containing gas dispensed into the water reservoir 29 may be introduced directly into the predetermined amount of water, thereby dispensing into the predetermined amount of water (preferably creating gas bubbles in the predetermined amount of water) as opposed to being introduced directly into the headspace above the predetermined amount of water. Additionally, although not shown, a sparger may be located in the water reservoir 29 at or near the first inlet 31. Such spargers, which may be conventional, may be used to generate small gas bubbles of oxygen-containing gas in a given volume of water. In the absence of such spargers, larger gas bubbles may be generated, which may be less desirable for mixing.

[0050] The system 11 may further include a water electrolysis device 41, also shown in FIG. 2. In this embodiment, the water electrolysis device 41 may be a type of water electrolysis device that includes a polymer electrolyte membrane (PEM), sometimes referred to as a proton exchange membrane. The water electrolysis device 41 may be similar in many respects to conventional PEM-type water electrolysis devices, such as, but not limited to, those described in U.S. Pat. No. 9,357,764, issued June 7, 2016, to inventors Tempelman et al., and U.S. Patent Application Publication No. 2022 / 0054318, published February 24, 2022, to inventors Schwenk et al., both of which are incorporated herein by reference.

[0051] The water electrolysis device 41 may include a polymer electrolyte membrane 45 , an anode 47 and a cathode 49 .

[0052] The polymer electrolyte membrane 45 is preferably a non-porous, ion-conductive, electrically non-conductive, liquid-permeable, and substantially gas-impermeable membrane. The polymer electrolyte membrane 45 may consist of or include a homogeneous perfluorosulfonic acid (PFSA) polymer. The PFSA polymer may be formed by copolymerization of tetrafluoroethylene and perfluorovinyl ether sulfonic acid. See, for example, U.S. Pat. No. 3,282,875, inventors Connolly et al., issued November 1, 1966; U.S. Pat. No. 4,470,889, inventors Ezzell et al., issued September 11, 1984; U.S. Pat. No. 4,478,695, inventors Ezzell et al., issued October 23, 1984; and U.S. Pat. No. 6,492,431, inventor Cisar, issued December 10, 2002. The entire contents of U.S. Pat. No. 6,492,431 are incorporated herein by reference. A commercially available embodiment of a PFSA polymer electrolyte membrane is manufactured by The Chemours Company FC, LLC (Fayetteville, NC) as NAFION™ extrusion-cast PFSA polymer membrane.

[0053] The polymer electrolyte membrane 45 may be a substantially flat, monolithic structure in the form of a continuous film or sheet. In this embodiment, the polymer electrolyte membrane 45 may have a substantially circular shape when viewed from above or below. Furthermore, the overall shape of the water electrolysis device 41 may generally correspond to the shape of the polymer electrolyte membrane 45 when viewed from above or below. However, it should be understood that the polymer electrolyte membrane 45 and the water electrolysis device 41 as a whole are not limited to a substantially circular shape, and may have a substantially rectangular, annular, or other suitable shape.

[0054] The anode 47 and the cathode 49 may be disposed along two opposing major surfaces of the polymer electrolyte membrane 45. For reasons that will become apparent below, in this embodiment the anode 47 is shown as being disposed along the lower surface of the polymer electrolyte membrane 45, and the cathode 49 is shown as being disposed along the upper surface of the polymer electrolyte membrane 45.

[0055] As best seen in FIG. 2 , the anode 47 may include an anode electrocatalyst layer 51 and an anode support 53. The anode electrocatalyst layer 51 may be disposed in direct contact with the polymer electrolyte membrane 45 and is shown in this embodiment as being disposed directly beneath and in contact with the lower surface of the polymer electrolyte membrane 45. The anode electrocatalyst layer 51 defines the electrochemically active area of ​​the anode 47 and is preferably sufficiently porous and electrically and ionically conductive to support a rapid surface oxidation reaction. The anode electrocatalyst layer 51, which may be of the type conventionally used in PEM-based water electrolysis devices, may include finely divided, electrically conductive, and optionally ionically conductive, electrocatalyst particles (e.g., metal powder) in a form capable of supporting a rapid electrochemical reaction. The electrocatalyst particles may be distributed within the anode electrocatalyst layer 51, preferably with an ionically conductive binder, to provide mechanical fixation.

[0056] The anode support 53, which may be a type of anode support conventionally used in PEM-based water electrolysis devices, may be, for example, a porous titanium film or sheet, and is preferably sufficiently porous to allow fluids (gas and / or liquid) to pass freely through it. To this end, the anode support 53 may have a pore size of, for example, about 0.001 to 0.5 mm. Furthermore, the anode support 53 is preferably electrically conductive to provide electrical connectivity between the anode electrode catalyst layer 51 and the anode current collector (described below). The anode support 53 is also preferably ionically non-conductive. The anode support 53 may be positioned in direct contact with the anode electrode catalyst layer 51; in this embodiment, the anode support 53 is shown positioned directly below the anode electrode catalyst layer 51 so that the anode electrode catalyst layer 51 can be sandwiched between and in contact with the polymer electrolyte membrane 45 and the anode support 53. The anode support 53 can be sized to completely cover the surface (e.g., the lower surface) of the anode electrocatalyst layer 51, and in practice, the anode 47 can be fabricated by depositing the anode electrocatalyst layer 51 on the anode support 53.

[0057] The cathode 49 may include a cathode electrocatalyst layer 55 and a cathode support 57. The cathode electrocatalyst layer 55 may be disposed in direct contact with the polymer electrolyte membrane 45 and is shown in this embodiment as being disposed directly above and in contact with the top of the polymer electrolyte membrane 45. The cathode electrocatalyst layer 55 defines the electrochemically active area of ​​the cathode 49 and is preferably sufficiently porous and electrically and ionically conductive to support a fast surface reduction reaction. The cathode electrocatalyst layer 55, which may be of the type conventionally used in PEM-based water electrolysis devices, may include electrocatalyst particles in the form of a finely divided, electrically and optionally ionically conductive material capable of supporting a fast electrochemical reaction (e.g., a metal powder). The electrocatalyst particles may be distributed within the cathode electrocatalyst layer 55 along with a binder, which is preferably ionically conductive, to provide mechanical fixation. The reactants and products involved in the anode 47 and cathode 49 may include ionic species that are mobile across the electroactive surfaces; therefore, an ionically conductive medium, including the polymer electrolyte membrane 45 and, optionally, one or more ionically conductive catalytic binders in the electrode catalyst layers 51 and 55, may bind the electrodes and allow ions to flow to sustain the overall electrochemical reaction.

[0058] The cathode support 57, which may be a type of cathode support conventionally used in PEM-based water electrolysis devices, may be, for example, a porous carbon film or sheet, and is preferably sufficiently porous to allow fluids (gas and / or liquid) to pass freely through it. To this end, the cathode support 57 may have a pore size of approximately 0.001 to 0.5 mm. Furthermore, the cathode support 57 is electrically conductive, providing electrical connectivity between the cathode electrode catalyst layer 55 and the cathode current collector, which will be described later. The cathode support 57 is also preferably ionically non-conductive. The cathode support 57 may be disposed in direct contact with the cathode electrode catalyst layer 55; in this embodiment, it is shown disposed directly above the cathode electrode catalyst layer 55 so that the cathode electrode catalyst layer 55 is sandwiched between and in contact with the polymer electrolyte membrane 45 and the cathode support 57. The cathode support 57 may be dimensioned to completely cover the surface (e.g., upper surface) of the cathode electrocatalyst layer 55, and in practice, the cathode 49 may be fabricated by depositing the cathode electrocatalyst layer 55 on the cathode support 57.

[0059] The combination of the polymer electrolyte membrane 45, the anode 47 and the cathode 49, or the combination of the polymer electrolyte membrane 45, the anode electrode catalyst layer 51 and the cathode electrode catalyst layer 55, may collectively be considered a membrane-electrode assembly (MEA).

[0060] The water electrolysis device 41 may further include an anode seal 61 and a cathode seal 63. The anode seal 61, which may be of a type conventionally used in PEM-based water electrolysis devices, may be a generally annular or frame-like member mounted liquid-tightly around the anode 47. (The anode seal 61 may be positioned in direct contact with the periphery of the anode 47, or a small gap may be provided between the anode seal 61 and the periphery of the anode 47 for ease of assembly.) The anode seal 61, which may be made of polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM) rubber, or other similarly suitable material, may be ionically and electrically non-conductive. The anode seal 61 may also be non-porous and fluid-impermeable.

[0061] The cathode seal 63, which may be of a type conventionally used in PEM-based water electrolysis devices, may be a generally annular or frame-like member mounted fluid-tightly around the cathode 49. (The cathode seal 63 may be positioned in direct contact with the periphery of the cathode 49, or there may be a small gap between the cathode seal 63 and the periphery of the cathode 49 for ease of assembly.) The cathode seal 63, which may be made of polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM) rubber, or other similarly suitable materials, may be ionically and electrically non-conductive. The cathode seal 63 may also be non-porous and fluid-impermeable.

[0062] In this embodiment, the anode 47 and anode seal 61 may be sized to cooperatively match the footprint of the lower surface of the polymer electrolyte membrane 45. Additionally, the cathode 49 and cathode seal 63 may also be sized to cooperatively match the footprint of the upper surface of the polymer electrolyte membrane 45. Notwithstanding the above, it should be understood that the footprints of the aforementioned components may differ from those described above.

[0063] The water electrolysis device 41 may further include an anode current collector 65. The anode current collector 65 may be similar to types of anode current collectors conventionally used in PEM-based water electrolysis devices, and may comprise, for example, a platinum-coated titanium sheet. When viewed from below, the anode current collector 65 may have a footprint that substantially matches the collective footprint of the anode 47 and anode seal 61, except that the anode current collector 65 may further include a tab 66 that extends radially outward a short distance beyond the periphery of the anode seal 61 and may be used as a terminal. The anode current collector 65 may also include a plurality of through-holes 67 through which oxygen produced at the anode 47 can pass.

[0064] The water electrolysis device 41 may further include a cathode current collector 71, which may comprise a cathode current collector of a type conventionally used in PEM-based water electrolysis devices, such as a platinum-coated titanium sheet. When viewed from below, the cathode current collector 71 may have a footprint that substantially matches the collective footprint of the cathode 49 and cathode seal 63, except that the cathode current collector 71 may further include a tab 73 that extends radially outward a short distance beyond the periphery of the cathode seal 63 and may be used as a terminal. The cathode current collector 71 may also include a plurality of through-holes 75 through which hydrogen produced at the cathode 49 can pass.

[0065] Although not shown, the water electrolysis device 41 may further include other components commonly found in conventional PEM-based water electrolysis devices. For example, the static force on the water electrolysis device 41 that may be required to compress the anode seal 61 and cathode seal 63 to maintain good electrical contact between the series components of the water electrolysis device 41 and to obtain a good seal around the cell periphery may be created and maintained using a variety of conventional fastening or joining devices and techniques around the inner or outer periphery of the assembly. Such devices may include, for example, fasteners (e.g., screws, rivets, etc.) capable of clamping end plates to either end of the series components, or adhesives, cements, or welds that join elements together within the sealing area. Such devices and techniques are known to those skilled in the art.

[0066] 1 , it can be seen that the water electrolysis device 41 may be electrically connected to the power source 25 via an electrical conduit 81, which may comprise one or more wires or a similarly suitable structure. The electrical conduit 81 may be connected to the anode 47 (via current collector 65) and to the cathode 49 (via current collector 71). In this embodiment, the power source 25, whose operation may be controlled by the controller 21, may be used to power the operation of the water electrolysis device 41 over a range of currents and voltages, and may be used to power the water electrolysis device 41 continuously or intermittently.

[0067] 1 , the water electrolysis device 41 and the water reservoir 29 may be coupled to one another such that (i) the water reservoir 29 can be used to supply water to the cathode 49 of the water electrolysis device 41, and (ii) the cathode 49 can be used to supply hydrogen gas to a predetermined amount of water contained in the water reservoir 29 for mixing with oxygen gas dispersed in the amount of water. In this embodiment, such coupling of the water electrolysis device 41 and the water reservoir 29 may involve integrating the water electrolysis device 41 and the water reservoir 29 into an electrolysis device / reservoir assembly 80, wherein at least a portion of the water electrolysis device 41, such as the cathode 49, may be disposed within the predetermined amount of water in the water reservoir 29.

[0068] As can be appreciated, operation of system 11 may consume a portion of the water present in water reservoir 29, some of which occurs as a result of electrolysis of water in water electrolysis device 41 and some of which occurs as humidification of the gas mixture exiting water reservoir 29. To ensure that a sufficient amount of water remains in water reservoir 29, system 11 may further include a water source (not shown) operably connected to water reservoir 29 to replenish the consumed water. Additionally or alternatively, water reservoir 29 may simply be replaced when water consumption reaches a certain point.

[0069] Referring now to FIG. 3 , one embodiment of an electrolyzer / reservoir assembly 80 is shown in more detail. As can be seen, the electrolyzer / reservoir assembly 80 may include a membrane electrode assembly 81. The membrane electrode assembly 81 may also include a cathode 49, a seal gasket 82, and an anode (not shown in FIG. 3 , but positioned below the seal gasket 82 and opposite the cathode 49). The electrolyzer / reservoir assembly 80 may further include a cathode current collector 71 and an anode current collector 65. The cathode current collector 71, which may have a porous central region 83 defining a fluid diffusion chamber for water uptake / hydrogen release, may be positioned against the upper surface of the cathode 49, and the anode current collector 65, which may have a porous central region 84 defining a fluid diffusion chamber for oxygen release, may be positioned against the lower surface of the anode.

[0070] The electrolyzer / reservoir assembly 80 may further comprise an annular cathode seal gasket 85 and an annular anode seal gasket 86. The cathode seal gasket 85 may be disposed in contact with the upper surface of the cathode current collector 71, and the anode seal gasket 86 may be disposed in contact with the lower surface of the anode current collector 65. The electrolyzer / reservoir assembly 80 may further comprise a cathode end plate 87 and an anode end plate 88. The cathode end plate 87, which may include a porous central region 87-1 for water uptake / hydrogen release, may be disposed in contact with the cathode seal gasket 85, and the anode end plate 88 may be disposed in contact with the anode seal gasket 86.

[0071] The electrolyzer / reservoir assembly 80 may further include oxygen outlet ports 89 and 90 that may be mechanically coupled to the anode end plate 88 and fluidly connected to the anode.

[0072] The electrolyzer / reservoir assembly 80 may further include a water reservoir 29 that may be positioned above the cathode end plate 87. A water reservoir seal O-ring 91 may be seated on the cathode end plate 87 and may be used to form a fluid seal for water passing from the reservoir 29 through the porous central region 87-1 of the cathode end plate 87. A reservoir clamp 92 may be attached to a reservoir seal plate 93 of the water reservoir 29.

[0073] The electrolyzer / reservoir assembly 80 may further include a reservoir outlet fitting 94 that may be coupled to the reservoir 29 via a reservoir outlet port 95, a reservoir water fill fitting 95 that may be coupled to the reservoir 29 via a reservoir water fill port 97, and a reservoir oxygen inlet fitting 98 that may be coupled to the reservoir 29 via a reservoir oxygen inlet port 99. A sparger 100 may be coupled to the outlet end of the reservoir oxygen inlet fitting 98.

[0074] The electrolyzer / reservoir assembly 80 may further include hardware for mechanically coupling many of the above-described components. Such hardware may include a plurality of screws 101 for assembly clamps, and a corresponding plurality of washers 103, 105, and nuts 107.

[0075] Referring again to FIG. 1 , operation of water electrolysis device 41 may produce oxygen gas at anode 47 and hydrogen gas at cathode 49. The oxygen gas produced at anode 47 may be vented from system 11 to the environment. (Such venting may occur through fluid conduit 118, one end of which is fluidly connected to the output of anode 47.) In contrast, hydrogen gas produced at cathode 49 may be added directly to a predetermined amount of water contained in water reservoir 29. In that case, such hydrogen gas may mix with oxygen gas supplied through inlet 35 and any other gases added to the predetermined amount of water contained in water reservoir 29. The combined gas may then exit water reservoir 29 through outlet 33.

[0076] The system 11 may further include a hydrogen gas sensor 111. The hydrogen gas sensor 111, which may be conventional, may be fluidly connected to the water reservoir 29 via a fluid conduit 113. The fluid conduit 113, which may consist of or comprise a tube or other structure suitable for axially transporting one or more fluids, may have an inlet end fluidly connected to the outlet 33 of the water reservoir 29 and an outlet end connected to the inlet of the hydrogen gas sensor 111. The hydrogen gas sensor 111 may also be electrically connected to the controller 21 via an electrical conduit 115, which may comprise a wire or a similarly suitable structure. In this embodiment, the electrical conduit 115 may be electrically connected to the hydrogen gas sensor 111 at a first end and to the controller 21 at a second end. In this aspect, depending on the hydrogen gas concentration of the hydrogen / oxygen-containing gas mixture sensed by the hydrogen gas sensor 111, the controller 21 may correspondingly modify the output of the power source 25, which in turn may modify the output of the water electrolysis device 41. As a result, the hydrogen gas sensor 111 can be useful for providing feedback control of the hydrogen gas concentration of the gas mixture. Additionally or alternatively, the hydrogen gas sensor 111 can provide confirmation that the hydrogen gas concentration is within a desired range.

[0077] System 11 may further include a fluid conduit 117. Fluid conduit 117, which may consist of or include tubing or other structure suitable for transporting one or more fluids in an axial direction, may have an inlet end and an outlet end. The inlet end may be fluidly connected to hydrogen gas sensor 111. The outlet end of fluid conduit 117 may be used to deliver the gas mixture to a desired destination. For example, if system 11 is a subsystem of a ventilation or breathing system, the outlet end of fluid conduit 117 may be connected to the inlet of a breathing mask or the like.

[0078] 4, there is shown a simplified schematic diagram of a second embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention and generally designated by the reference numeral 121. Details of system 121 that are described elsewhere in this application or that are not important to an understanding of the present invention may be omitted from FIG. 4 or the accompanying description herein, or may be shown in FIG. 4 and / or described in a simplified manner herein.

[0079] System 121 may be similar in many respects to system 11. One difference between system 121 and system 11 may be that system 11 may be configured to exhaust oxygen gas produced at anode 47 to the environment, whereas system 121 may instead add such oxygen gas to the hydrogen / oxygen gas mixture exiting water reservoir 29. To this end, system 121 may include fluid conduit 123. Fluid conduit 123, which may consist of or comprise a tube or other structure suitable for transporting one or more fluids axially, may have an inlet end fluidly connected to the output of anode 47 and an outlet end fluidly connected to fluid conduit 113.

[0080] As can be appreciated, in another embodiment (not shown), instead of adding oxygen gas produced at anode 47 directly to the hydrogen / oxygen mixture already exiting water reservoir 29, as is the case with system 121, such oxygen gas may be added to a predetermined amount of water residing in water reservoir 29. In either case, whether the added oxygen is added to the hydrogen / oxygen mixture already exiting water reservoir 29 or to a predetermined amount of water residing in water reservoir 29, adding such oxygen may reduce oxygen dilution that can occur when using system 121.

[0081] 5, there is shown a simplified schematic diagram of a third embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention and generally designated by the reference numeral 131. Details of system 131 that are described elsewhere in this application or that are not important to an understanding of the present invention may be omitted from FIG. 5 or the accompanying description herein, or may be shown in FIG. 5 and / or described in a simplified manner herein.

[0082] System 131 may be similar in many respects to system 121. One difference between system 131 and system 121 is that system 121 may include water reservoir 29 configured with inlet 31 for receiving an oxygen-containing gas, while system 131 may include water reservoir 133 further configured with inlet 135 for receiving one or more additional gases, such as, but not limited to, therapeutic gases (e.g., anesthesia, nitric oxide). To this end, system 131 may include fluid conduit 137. Fluid conduit 137, which may consist of or comprise a tube or other structure suitable for transporting one or more fluids in an axial direction, may have an inlet end fluidly connected to a gas source and an outlet end fluidly connected to inlet 135. Preferably, the one or more additional gases delivered to water reservoir 133 are dispensed below a water level line of a predetermined volume of water within water reservoir 133. In this embodiment, mixing of the additional gas with the hydrogen gas and oxygen gas dispensed into the predetermined amount of water can be facilitated so that the gas mixture exiting the water reservoir 133 can include a mixture of hydrogen gas, oxygen gas, and one or more additional gases.

[0083] As can be appreciated, the additional gas in fluid conduit 137 may alternatively be joined to the system of 131 through fluid conduit 13 and / or fluid conduit 35 .

[0084] Also, as can be appreciated, system 131 may be modified so that the oxygen gas added to the hydrogen-containing gas mixture can instead be vented to the environment.

[0085] Referring now to Figure 6, there is shown a simplified schematic diagram of a fourth embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention and generally designated by the reference numeral 141. Details of system 141 that are described elsewhere in this application or that are not important to an understanding of the present invention may be omitted from Figure 6 or the accompanying description herein, or may be shown in Figure 6 and / or described in a simplified manner herein.

[0086] System 141 may be similar in many respects to system 131. One difference between system 141 and system 131 may be that while system 131 may include water electrolysis device 41, system 141 may instead include water electrolysis device 143. Water electrolysis device 143 may be similar in many respects to water electrolysis device 41 and may include a polymer electrolyte membrane 145, which may be similar to polymer electrolyte membrane 45, an anode 147, which may be similar to anode 47, and a cathode 149, which may be similar to cathode 49. However, one notable difference between water electrolysis device 143 and water electrolysis device 141 may be that in water electrolysis device 143, anode 147 may be positioned above polymer electrolyte membrane 145 and cathode 149 may be positioned below polymer electrolyte membrane 145, whereas in water electrolysis device 41, cathode 49 may be positioned above polymer electrolyte membrane 45 and anode 47 may be positioned below polymer electrolyte membrane 45. As a result, in system 141, anode 147 may be disposed within a predetermined volume of water in water reservoir 133 and may be used to deliver oxygen gas directly to the predetermined volume of water so that the oxygen gas may mix with the oxygen gas delivered by fluid conduit 35 and the additional gas or gases delivered by fluid conduit 137. Additionally, cathode 149 may be disposed outside of the predetermined volume of water in water reservoir 133, such that hydrogen gas produced at cathode 149 may not be delivered directly to water reservoir 133. Instead, such hydrogen gas may be added to the predetermined volume of water in water reservoir 133 at inlet 150.

[0087] 7, there is shown a simplified schematic diagram of a fifth embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention and generally designated by the reference numeral 151. Details of system 151 that are described elsewhere in this application or that are not important to an understanding of the present invention may be omitted from FIG. 7 or the accompanying description herein, or may be shown in FIG. 7 and / or described in a simplified manner herein.

[0088] System 151 may be similar in many respects to system 11. For example, like system 11, system 151 may include fluid conduit 13, gas flow meter 19, controller 21, electrical conduit 23, power supply 25, electrical conduit 27, electrical conduit 81, hydrogen gas sensor 111, fluid conduit 113, electrical conduit 115, and fluid conduit 117. However, system 151 may differ from system 11 in that while system 11 includes a water reservoir and water electrolysis device integrated into electrolyzer / reservoir assembly 80, such that at least the electrolyzer cathode 49 of water electrolysis device 41 may be disposed within a volume of water in water reservoir 29, system 151 may include a water reservoir and water electrolysis device that are not integrated as described above. Alternatively, system 151 may include a combination of water reservoir 153, water pump 155, and water electrolysis device 157, all of which may be physically separated from one another.

[0089] More specifically, the water reservoir 153 may be generally similar to the water reservoir 29 of the system 11, but may further include a water outlet 159. A fluid conduit 161, which may consist of or include a tube or other similarly suitable structure configured to direct a fluid in an axial direction, may be connected at a first end to the water outlet 159 and at a second end to an inlet of a water pump 155. The water pump 155, which may be conventional, may be used to pump water from the water reservoir 153 to an electrolyzer cathode 159 of the water electrolysis device 157. To this end, a fluid conduit 163, which may consist of or include a tube or other similarly suitable structure configured to direct a fluid in an axial direction, may be connected at a first end to the outlet of the water pump 155 and at a second end to the water electrolysis device 157 to deliver water to the electrolyzer cathode 159. Additionally, a fluid conduit 165, which may consist of or comprise a tube or other similarly suitable structure configured to axially direct a fluid, may be connected at a first end to the electrolyzer cathode 159 of the water electrolysis device 157 and at a second end to a hydrogen gas inlet of the water reservoir 153. In this embodiment, hydrogen gas, which may be produced at the electrolyzer cathode 159 of the water electrolysis device 157, may be delivered to a predetermined volume of water in the water reservoir 153 for mixing with any delivery gas present in the predetermined volume of water.

[0090] The power supply 25, whose operation can be controlled by the controller 21, can be used to power the operation of the water electrolysis device 157 over a range of currents, voltages and water flow rates, and can be used to power the water electrolysis device 157 continuously or intermittently.

[0091] System 151 may be more desirable than system 11 in some respects. For example, system 11 is configured to rely on constant flooding of water electrolysis device 41 with substantially stagnant water. As can be appreciated, this may be difficult to achieve in practice. In contrast, system 151 may utilize pump 155 to help circulate water through water electrolysis device 157.

[0092] Referring now to Figure 8, there is shown a simplified schematic diagram of a sixth embodiment of a system for generating a gas mixture, the system being constructed in accordance with the present invention and generally designated by the reference numeral 171. Details of system 171 that are described elsewhere in this application or that are not important to an understanding of the present invention may be omitted from Figure 8 or the accompanying description herein, or may be shown in Figure 8 and / or described in a simplified manner herein.

[0093] System 171 may be similar in many respects to system 151. One difference between system 171 and system 151 is that system 151 may include a water electrolysis device 157 that includes a single electrolysis cell, while system 171 may include a water electrolysis device 173 that includes a stack of electrolysis cells. As can be appreciated, a stack of electrolysis cells may be capable of producing larger amounts of gas than a single cell, particularly without significantly increasing the footprint of the water electrolysis device. This may make system 171 more useful in higher flow respiratory systems, particularly in typical hospital settings where greater amounts of hydrogen are required for treatment. It would be difficult to include such a stack in water reservoir 153 itself, as it would be difficult to flood each cathode in such a stack to the required extent. This problem may be ameliorated in system 171 by providing a pump that supplies water to the various cathodes in the stack.

[0094] Another difference between system 171 and system 151 is that while system 151 may supply water directly from water reservoir 153 to pump 155 through fluid conduit 161, system 171 may further include an air bubble eliminator 175, which may be disposed between water reservoir 153 and pump 155. Air bubble eliminator 175, which may be conventional, may reduce or minimize the presence of air bubbles in the water supplied to pump 155, which may interfere with the operation of pump 155. In this embodiment, by providing air bubble eliminator 175, water may be transferred from water reservoir 153 to air bubble eliminator 175 through fluid conduit 161, and then transferred from air bubble eliminator 175 to pump 155 through fluid conduit 177 (which may be similar in structure and function to fluid conduit 161), reducing or minimizing the presence of air bubbles in the water reaching pump 155.

[0095] It should be understood that systems 151 and 171 may be modified so that oxygen generated at one or more anodes may be added to a predetermined amount of water in the water reservoir or to the gas mixture after it leaves the water reservoir. Additionally or alternatively, systems 151 and 171 may be modified so that one or more additional gases, such as anesthesia or nitric oxide, may be added to water reservoir 153 directly or by introduction into fluid conduit 13 or 35.

[0096] As can be appreciated, it may be desirable for the combined oxygen and hydrogen gas exiting the water reservoir to draw a certain amount of water vapor from the water reservoir, but it may be undesirable for the amount of water vapor to exceed such amount or remain in a liquid state. Accordingly, referring now to Figure 9, there is shown schematically one embodiment of a baffled fluid conduit of a type that may be positioned at the gas outlet of a water reservoir in accordance with the present invention, said baffled fluid conduit being generally designated by the reference numeral 191. The baffled fluid conduit 191 may be designed to return liquid by gravity to the water reservoir, allowing a humidified phase to be delivered, for example, for administration to a patient or other destination.

[0097] As mentioned above, the present invention is also directed to systems that can deliver dilute mixtures of the above-mentioned gases to humans for therapeutic use using devices such as, but not limited to, ventilators, oxygen face masks and cannulas, anesthesia machines, respirators, high-flow ventilators, and extracorporeal membrane oxygenation (ECMO).

[0098] Existing ventilator systems for respiratory therapy typically include a wide variety of configurations but generally include the same functionality. More specifically, generally speaking, a source of oxygen-enriched gas, such as pure medical-grade oxygen, air, mixtures thereof, or mixtures with other gases, is connected to a ventilator. The ventilator is connected to a circuit piping system that delivers and receives respiratory gas flow to and from the patient's breathing apparatus during breathing and actively delivers oxygen-enriched gas to the circuit, with or without an integrated humidifier. The delivered gas may be partially recirculated, in which case the ventilator may exhaust a portion of the return (exhaled) gas and actively reduce carbon dioxide in the recirculated portion using a scrubber. The amount of gas delivered from the ventilator may be controlled by various pressure, volume, or flow control algorithms, all driven by the patient's respiratory rhythm, including the oxygen-enriched gas supply flow rate, ventilator pump flow rate, circuit flow control valves, and feedback from pressure, flow rate, blood oxygen concentration, and / or other sensors. The circuit may be fitted with a heating system to prevent condensation of the humidified gas, which is typically adjusted to a dew point near normal physiological temperature (approximately 35°C). A more detailed discussion of the uses and types of ventilation devices can be found, for example, in Tai Pham, Laurent J. Brochard, and Arthur S. Slutsky, "Mechanical Ventilation: State of the Art," Mayo Clinic Proceedings, Volume 92, Issue 9, 2017, Pages 1382-1400; U.S. Patent No. 10,821,259, issued November 3, 2020, to inventor Borrello; and U.S. Patent No. 11,247,016, issued February 15, 2022, to inventor Novkov, all of which are incorporated herein by reference.

[0099] Referring now to Figure 10, there is shown a simplified schematic diagram of a first embodiment of a ventilator circuit, the system being constructed in accordance with the present invention and generally designated by the reference numeral 201. Details of system 201 that are described elsewhere in this application or that are not important to an understanding of the present invention may be omitted from Figure 10 or the accompanying description herein, or may be shown in Figure 10 and / or described in a simplified manner herein.

[0100] System 201 may include an air or oxygen gas source 203, which may be, for example, one or more gas tanks containing air, oxygen-enriched air, or pure oxygen. System 201 may further include a conventional ventilation device 205. A fluid conduit 207, which may be a tube or similar suitable structure configured to transport one or more fluids axially therethrough, may have a first end fluidly connected to an outlet of air or oxygen gas source 203 and a second end fluidly connected to an inlet of ventilation device 205.

[0101] System 201 may further include a hydrogen generation / mixing subsystem 209 that may be used to generate hydrogen gas, preferably by electrolysis of water, and mix such hydrogen gas with air or oxygen gas supplied by ventilation device 205. Hydrogen generation / mixing subsystem 209 may be fluidly connected to ventilation device 205 via fluid conduit 211, which may be similar in structure and function to fluid conduit 207. Hydrogen generation / mixing subsystem 209 may include a combination of water reservoir 213 and water electrolysis device 215. As can be appreciated, hydrogen generation / mixing subsystem 209 may include a system such as one of systems 11, 121, 131, 141, 151, and 171. More specifically, the water reservoir 213 may comprise a water reservoir similar to or identical to one of the water reservoirs 29, 133 and 153, and the water electrolysis device 215 may comprise a water electrolysis device similar to or identical to a corresponding one of the water electrolysis devices 41, 143, 157 and 173.

[0102] System 201 may further include a patient respiratory interface device 217, which may be, for example, a mask, cannula, or other suitable respiratory apparatus of the type conventionally used to administer gases to patients by inhalation. Device 217 may be fluidly connected to hydrogen generation / mixing subsystem 209 via fluid conduit 219 and may be similar in structure and function to fluid conduit 207.

[0103] System 201 may further include a fluid conduit 221. Fluid conduit 221 may be similar in structure and function to fluid conduit 207 and may be used to transport exhaled gases from the patient through device 217 to ventilator 205.

[0104] As can be appreciated, because the hydrogen generation / mixing subsystem 209 produces humidified gas, the hydrogen generation / mixing subsystem 209 can eliminate the need for a dedicated humidifier in the system 201 .

[0105] 11, there is shown a simplified schematic diagram of a second embodiment of a ventilator circuit, the system being constructed in accordance with the present invention and generally designated by the reference numeral 251. Details of system 251 that are described elsewhere in this application or that are not important to an understanding of the present invention may be omitted from FIG. 11 or the accompanying description herein, or may be shown in FIG. 11 and / or described in a simplified manner herein.

[0106] System 251 may be similar in many respects to system 201. One difference between system 251 and system 201 may be that system 251 may further include a humidifier 253, which may be similar to a conventional humidifier of the type commonly found in ventilation systems. Humidifier 253 may be placed in series before hydrogen generation / mixing subsystem 209 and may be used to provide additional humidification so that the mixed gas delivered to the patient has a desired level of humidification.

[0107] The following examples are provided for illustrative purposes only and are not meant to be limitations on the invention described herein or the claims appended hereto. Example 1

[0108] A single-cell water electrolysis device (40 cm) with a 150 μm thick perfluorosulfonic acid proton exchange membrane (equivalent weight of dry polymer of approximately 1100 g per mole of sulfonic acid group), an iridium anode catalyst on a porous titanium current collector, and a platinum cathode catalyst on a porous carbon current collector) was used. 2 The active area (of the cathode and cathode) was constructed using the general structure disclosed in U.S. Patent No. 10,091,985, issued October 9, 2018, by inventors Tempelman et al., which is incorporated herein by reference. Here, the anode and cathode electrode compositions were swapped, and an integrated water electrolysis device (approximately 500 cc capacity) was included in the configuration shown in FIG. 1, in direct contact with and positioned on the cathode current collector, but without a controller to control production. The electrolysis device current and oxygen gas flow rate setpoints were managed by an operator (manual current setpoint to the power supply based on manual calculations of Faraday's Law and the oxygen controller flow rate setpoint). Titanium plates were used to clamp the hardware with approximately 2000 pounds of force (to form a fluid seal, maintain the flow path specified by the flow field, and ensure adequate contact pressure for electrical conductivity and mechanical support of the membrane). Here, the cathode side plate sandwiched the cathode current collector and the reservoir, and the cathode side plate had a large slot at the bottom of the reservoir to facilitate fluid communication. An O-ring seal kept the water in the reservoir, which had three ports on the top surface for oxygen inlet, oxygen outlet, and temperature probing. The oxygen inlet was terminated with a plastic sparger, and the electrolyzer reservoir was filled with deionized water. The anode outlet was open directly to the atmosphere. The current was increased to 0.4 A, 1.6 A, 2.7 A, and 5.4 A (approximately 138 mA / cm) over a 70-minute period. 2 The water temperature in the electrolyzer is not heated, but instead flows at a maximum of 5.5A (138mA / cm2 ) during approximately 2 hours of operation, significant cooling occurred from 23.0°C to 21.7°C. This suggests that the cooling potential of humidifying the dry oxygen was greater than the ohmic heating power of the operating electrolyzer. This configuration was able to reliably and safely produce 0.25 to 2.2% by volume hydrogen-oxygen mixtures at 1.0 and 2.0 SLPM (standard liters per minute). The electrolyzer was operated at 138 mA / cm 2 It operated with high efficiency up to 1000 kJ / s and without any apparent mass transfer limitations.

[0109] Figure 12 is a graph showing the change in hydrogen concentration, oxygen flow rate, and cell current over time during constant current electrolysis of water using the above-described configuration. Figure 13 is a graph showing the hydrogen concentration measured at the reservoir outlet while delivering 1.0 SLPM of sparging oxygen to the electrolyzer reservoir during steady state electrolysis at 2.7 A using the above-described configuration. Figure 14 is a polarization plot using the above-described configuration. Example 2

[0110] A three-cell bipolar water electrolysis system (50 cm ) with an 1100 equivalent perfluorosulfonic acid proton exchange membrane, an iridium anode catalyst on a porous titanium current collector, and a platinum cathode catalyst on a porous carbon current collector) was used. 2The cells (active areas) are constructed in a manner similar to that known in the art. Titanium or stainless steel plates are used to clamp the hardware together (sufficient to form a fluid seal, maintain the flow paths specified by the flow fields, and ensure adequate contact pressure for electrical conductivity and membrane mechanical support), where the bipolar separator plates are constructed of titanium sandwiching the cells and optionally have a conductive coating to reduce contact resistance and oxidation. The end plates and bipolar separators have ports and manifolds for fluid pathways for water supply and hydrogen and oxygen gas removal between the inlet and outlet paths at the edges of each cell active area. The cells are connected electronically and electrolytically in series but fluidically plumbed in parallel. The end plates, or optionally the end separators, are utilized for connection to a DC power source. Flow fields are interposed between the separator and current collector of each anode and cathode, providing compressive force and electrical conductivity for low cell resistance and defined channels for uniform fluid delivery. The anode outlet is open directly to the atmosphere, releasing electrolytically generated oxygen and some water vapor. With an adequate supply of pure water and temperature control means, the electrolyzer can withstand large currents (i.e., 30 A or more) and thereby efficiently produce oxygen and hydrogen over extended periods of continuous or discontinuous operation. A heat exchanger is optionally placed between the water pump and the electrolyzer inlet to heat or cool the system to the desired humidifier temperature.

[0111] The medical oxygen supply of the three-cell bipolar electrolyzer flows into a sparger in a separate humidifier reservoir, and water in this humidifier reservoir is recirculated across the electrolyzer cathode using an interposed pump. With an oxygen supply to the humidifier sparger of 20 SLPM, applying a current of 18.3 ADC results in a humidifier outlet stream composed of humidified oxygen containing 2% hydrogen by volume. Additional advantages, aspects, and features that may be applicable to one or more embodiments of the present invention include the following.

[0112] One or more embodiments of the present invention can be used to produce hydrogen-oxygen or hydrogen-air gas mixtures of desired composition, preferably having a hydrogen concentration below the lower explosive limit, more preferably 4% or less by volume of hydrogen in air or oxygen, and even more preferably about 0.5-2% by volume of hydrogen in air or oxygen. Such gas mixtures can also have oxygen concentrations of about 20% to slightly less than 100% by volume (e.g., 99.95% by volume).

[0113] In one or more embodiments of the present invention, the system may be configured to add 1.0-2.4 SLPM of hydrogen to 60 SLPM of air or oxygen, or to add lesser amounts of air or oxygen to provide up to 4% hydrogen by volume.

[0114] One or more embodiments of the present invention may be applicable to invasive (i.e., for intubation critical care applications) and non-invasive ventilator types, and the present invention may be included within the specifications of the ventilator product, where a humidifier may be further integrated within the ventilator product.

[0115] The mixing of hydrogen and oxygen gases in water according to the present invention reduces the possibility that the gases will react and cause a safety hazard such as an explosion or combustion.

[0116] In at least one embodiment, an aspect of the invention is a system comprising a water electrolyzer, a cathode feed pump, and a recirculating water reservoir with an oxygen sparger for producing a hydrogen-oxygen mixture under operation of a constant oxygen flow rate and electrolyzer current.

[0117] In at least one embodiment, an aspect of the invention is a system comprising a water electrolysis device and a cathode-contacted water reservoir with an oxygen sparger to produce a hydrogen-oxygen mixture under operation of a constant oxygen flow rate and electrolyzer current.

[0118] In at least one embodiment, the water reservoir serves at least two purposes: (i) providing a source of water to be electrolyzed by the water electrolysis device, and (ii) providing a medium in which oxygen gas and hydrogen gas may safely mix. Mixing may also occur in the headspace above the water in the reservoir, although such mixing in the headspace may be less safe than in water.

[0119] The present invention may be used to generate gas mixtures that can be used to treat certain physical disorders, including, but not limited to, ischemia-reperfusion injury, particularly to brain tissue. More generally, there are numerous medical indications in which H2 may be beneficial in mitigating tissue damage, including ischemic stroke, cardiac arrest, myocardial infarction, cardiac bypass surgery, traumatic brain injury, concussion, cerebral palsy, and other indications in which the mechanism of injury may be related to ischemia-reperfusion injury due to oxidative or inflammatory damage. Ischemia-reperfusion injury can occur when blood is blocked from almost any organ, including the heart, brain, intestines, limbs, and skin. The present invention may be used in indications in which the mechanism of injury and the mechanism of protection or repair are not specifically or precisely known, such as an adjunct to other cancer treatments, sudden hearing loss, and kidney disease or injury. The present invention may be used to treat any or all of these conditions, as well as other conditions.

[0120] The above-described embodiments of the present invention are intended to be merely exemplary, and those skilled in the art will be able to make numerous variations and modifications without departing from the spirit of the present invention, and all such variations and modifications are intended to be within the scope of the present invention. [Prior art documents] [Patent documents]

[0121] [Patent Document 1] U.S. Patent No. 1,141,4765 [Patent Document 2] U.S. Patent No. 11105003 [License 3] U.S. Patent No. 10265665 [License 4] U.S. Patent No. 9050278 [Patent Document 5] U.S. Patent and Trademark Office Publication No. 202020 / 0368272 [License 6] U.S. Patent and Trademark Office Publication No. 2018 / 0295833 [License 7] U.S. Patent and Trademark Office Publication No. 2015 / 0292091 [License 8] Patent No. 6712924 [License 9] Japanese Patent Application Publication No. 2016-000081 [License 10] Japanese Patent Application Publication No. 2023-072784 [Non-licensed literature]

[0122] [Non-licensed Document 1] Ohsawa et al., "Hydrogen act as a therapeutic antoxidant by selectively reducing cytotoxic oxygen radical," Nature Medicine, 13(6):688-694(2007) [Non-licensed Document 2] Cole et al., “Safety of Prolonged Inhalation of Hydrogen Gas in Air in Healthy Adults,” Critical Care Explorations, 3(10):e543(2021) [Non-licensed Document 3] Cole et al.,”Perioperatively Inhaled Hydrogen Gas Diminishes Neurologic Injury Following Experimental Circulatory Arrest in Swine,”J Am Coll Cardiol Basic Trans Science,4(2):176-87(2019)

Claims

1. 1. A system for generating a gas mixture, comprising: a water reservoir comprising a volume of water, a first gas inlet through which a first delivery gas is delivered to said volume of water, and a gas outlet through which the gas mixture exits said water reservoir; a water electrolysis device connected to the water reservoir for receiving water from the volume of water and delivering a first product gas to be added to the volume of water; Equipped with The system wherein the first delivery gas and the first product gas mix in the volume of water to form the gas mixture and exit the water reservoir through the gas outlet.

2. The system of claim 1 , wherein the first delivery gas is oxygen and the first product gas is hydrogen.

3. 10. The system of claim 1, wherein the first delivery gas is one of air and oxygen-enriched air, and the first product gas is hydrogen.

4. The system of claim 1 , wherein at least a portion of the water electrolysis device is disposed within the volume of water in the water reservoir.

5. 5. The system of claim 4, wherein the first product gas is hydrogen, and the water electrolysis device comprises a cathode, the cathode being disposed in the volume of water in the water reservoir to deliver hydrogen directly into the volume of water.

6. 6. The system of claim 5, wherein the water electrolysis device further comprises an anode for conducting a second product gas, and the system further comprises a first fluid conduit for discharging the second product gas.

7. 6. The system of claim 5, wherein the water electrolysis device further comprises an anode for conducting a second product gas, and the system further comprises a second fluid conduit for transporting the second product gas to the gas mixture at a location external to the water reservoir.

8. The system of claim 1 , wherein the water electrolysis device is located entirely outside the water reservoir.

9. 10. The system of claim 8, further comprising a pump fluidly connected between the water reservoir and the water electrolysis device for pumping water from the water reservoir to the water electrolysis device.

10. The system of claim 9 , wherein the pump is a cathode feed pump.

11. 10. The system of claim 9, wherein the water electrolysis device comprises a single electrolysis cell.

12. 10. The system of claim 9, wherein the water electrolysis device comprises a bipolar stack of electrolysis cells.

13. The system of claim 12 further comprising an air bubble remover disposed in-line between the water reservoir and the pump.

14. 10. The system of claim 1, wherein the water electrolysis device comprises a polymer electrolyte membrane, an anode operably coupled to one side of the polymer electrolyte membrane, and a cathode operably coupled to an opposite side of the polymer electrolyte membrane.

15. The system of claim 1 , wherein the water reservoir further comprises a second gas inlet through which a second delivery gas is delivered to the volume of water.

16. The system of claim 1 , wherein the second delivery gas comprises at least one therapeutic gas selected from the group consisting of anesthesia and nitric oxide.

17. 10. The system of claim 1, wherein the gas mixture comprises hydrogen and oxygen, and the hydrogen concentration does not exceed 4% by volume.

18. 10. The system of claim 1, further comprising a power supply for supplying power to the water electrolysis device and a controller for controlling an output of the power supply.

19. 20. The system of claim 18, further comprising a gas flow meter for measuring a gas flow rate of the first delivery gas relative to the volume of water, the gas flow meter operably connected to the controller.

20. 20. The system of claim 18, further comprising a hydrogen gas sensor for measuring a hydrogen concentration of the gas mixture, the hydrogen gas sensor operably connected to the controller.

21. an oxygen-containing gas supply source that supplies a predetermined amount of oxygen-containing gas; a ventilation device operably connected to the oxygen-containing gas source for receiving the oxygen-containing gas and for delivering the oxygen-containing gas; 10. The system for generating a gas mixture of claim 1, wherein the oxygen-containing gas is the first delivery gas and the first product gas is hydrogen gas, such that the gas mixture comprises oxygen and hydrogen; a patient ventilation interface device operably coupled to the ventilator and to a system for generating the gas mixture such that the gas mixture is administered to a patient by inhalation; A ventilation system comprising:

22. 1. A method for generating a gas mixture, comprising: providing a water reservoir comprising a predetermined amount of water, a first gas inlet through which a first delivery gas is delivered to the predetermined amount of water, and a gas outlet through which a gas mixture exits the water reservoir; providing a water electrolysis device, the water electrolysis device connected to the water reservoir for receiving water from the quantity of water and delivering a first product gas to be added to the quantity of water; delivering the first delivery gas to the volume of water; operating the water electrolysis device to generate the first product gas; Including, The method wherein the first delivery gas and the first product gas mix in the volume of water to form the gas mixture and exit the water reservoir through the gas outlet.

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