Methods, systems, and apparatus for an active fuel cooling system (fuel cooling system). The fuel cooling system includes a fuel tank configured to store fuel. The fuel cooling system includes one or more pipes positioned adjacent to, in contact with, or within the fuel tank that are configured to deliver refrigerant that cools the fuel tank. The fuel cooling system includes a compressor for pumping the refrigerant through the one or more pipes to cool the fuel stored within the fuel tank. The fuel cooling system includes an electronic control unit connected to the compressor and configured to operate the compressor to pump the refrigerant through the one or more pipes to cool the fuel stored in the fuel tank.

The invention defines a combined system of sensor(s), control logic, air intake and contaminant deflector for a fuel cell system mounted on an aircraft, which will detect contamination in the free air flow surrounding the aircraft and if excessive contamination is detected will activate the contaminant deflector to protect the fuel cell system from contamination, damage and power loss. The system ensures constant speed of the aircraft by adjusting the power of the fuel cells to compensate any change in aircraft drag and adjusts the speed of any connected compressors to maintain and achieve necessary changes in power and compensation for any air pressure losses the system creates.

The invention defines a combined system of sensor(s), control logic, air intake and contaminant deflector for a fuel cell system mounted on an aircraft, which will detect contamination in the free air flow surrounding the aircraft and if excessive contamination is detected will activate the contaminant deflector to protect the fuel cell system from contamination, damage and power loss. The system ensures constant speed of the aircraft by adjusting the power of the fuel cells to compensate any change in aircraft drag and adjusts the speed of any connected compressors to maintain and achieve necessary changes in power and compensation for any air pressure losses the system creates.

A method of controlling a hydrogen partial pressure can be carried out in a fuel cell system including a stack having a hydrogen electrode and an air electrode. The method includes: determining a point of time to purge the hydrogen electrode using a hydrogen concentration at an outlet of the hydrogen electrode or an accumulated amount of charge generated in the stack; and setting a target supply pressure of hydrogen supplied to the stack, in which the target hydrogen supply pressure is set in consideration of a hydrogen pressure and a partial pressure of nitrogen resulting from crossover in the stack.

A carbon dioxide production system 10A includes: a fuel cell stack 16; a separation unit 20 that separates anode off-gas into a non-fuel gas including at least carbon dioxide and water and a regenerative fuel gas; a second heat exchanger 32 that separates water from the non-fuel gas; a water tank 42; and a carbon dioxide recovery tank 48 that recovers the carbon dioxide after the water has been separated.

A carbon dioxide production system 10A includes: a fuel cell stack 16; a separation unit 20 that separates anode off-gas into a non-fuel gas including at least carbon dioxide and water and a regenerative fuel gas; a second heat exchanger 32 that separates water from the non-fuel gas; a water tank 42; and a carbon dioxide recovery tank 48 that recovers the carbon dioxide after the water has been separated.

The invention relates to a fuel cell system (1) suitable for operation with a cathode operating gas containing oxygen and inert gas and an anode operating gas containing hydrogen and inert gas; an appliance system operated by means of the fuel cell system (1); and a method for operating the fuel cell system (1). In the method according to the invention, the single components of the operating gases are stored separately, and mixed to the required portions during operation of the fuel cell system, thereby constantly recirculating the inert portion of the operating gases. During operation of the fuel cell system, gases are neither taken in from the environment nor released into the environment nor are fuel cell exhaust gases stored in the fuel cell system or the appliance system. In an alternative variation, only the anode operating gas is mixed and recirculated, while the cathode operating gas and the cathode exhaust gas are taken from the environment and released into the environment, respectively.

The invention relates to a fuel cell system (1) suitable for operation with a cathode operating gas containing oxygen and inert gas and an anode operating gas containing hydrogen and inert gas; an appliance system operated by means of the fuel cell system (1); and a method for operating the fuel cell system (1). In the method according to the invention, the single components of the operating gases are stored separately, and mixed to the required portions during operation of the fuel cell system, thereby constantly recirculating the inert portion of the operating gases. During operation of the fuel cell system, gases are neither taken in from the environment nor released into the environment nor are fuel cell exhaust gases stored in the fuel cell system or the appliance system. In an alternative variation, only the anode operating gas is mixed and recirculated, while the cathode operating gas and the cathode exhaust gas are taken from the environment and released into the environment, respectively.

A method is provided for restoring an electrolyte of vanadium (V) redox flow battery (VRFB). Electrolyte data of an original system are analyzed in advance. A reusable positive electrode is further equipped with a V electrolyte. A reductant for a stack of VRFB is used in coordination as an electrolysis device. After a long-term reaction with a VRFB having a high valence (greater than 3.5), an electrolyte at the positive electrode is directed out to a negative electrode of the electrolysis device; and, then, electrolysis is processed after accurate calculation. In the end, the internal fluid balancing method of the original system is combined. Thus, a harmless and quick valence restoration is processed for the electrolyte of the original system, which is a final resort for the restoration of V electrolyte.

A redox flow battery includes first and second cells. Each cell has electrodes and a separator layer arranged between the electrodes. A first circulation loop is fluidly connected with the first electrode of the first cell. A polysulfide electrolyte solution has a pH 11.5 or greater and is contained in the first recirculation loop. A second circulation loop is fluidly connected with the second electrode of the second cell. An iron electrolyte solution has a pH 3 or less and is contained in the second circulation loop. A third circulation loop is fluidly connected with the second electrode of the first cell and the first electrode of the second cell. An intermediator electrolyte solution is contained in the third circulation loop. The cells are operable to undergo reversible reactions to store input electrical energy upon charging and discharge the stored electrical energy upon discharging.