Patent Description:
In recent years, hydrogen-powered vehicles (e.g., automotives, aircraft, buses, ships, etc.) have become more prevalent. As such, advancements in hydrogen storage tanks and refueling measures for such tanks are ever increasing. A typical liquid hydrogen (LH2) refueling system includes a supply tank and/or trailer, a flow control valve, a volumetric flowmeter, a cryogenic valve, and vacuum-jacketed flowlines. Along with the onboard LH2 tank(s), some hydrogen-powered vehicles (e.g., aircraft) include a cryogenic pump or other mechanism(s) to supply gaseous hydrogen (GH2) to engine(s) for combustion and power generation. Some hydrogen -powered vehicles include onboard cryo-compressed hydrogen (CcH2) tank(s) to store hydrogen in a supercritical state (e.g., supercritical gas) at pressures higher than LH2 tanks but at similar densities. For example, CcH2 tanks can store CcH2 with densities ranging from <NUM> kilograms per cubic meter (kg/m<NUM>) to <NUM>/m<NUM>, pressures ranging from <NUM> bar to <NUM> bar, and cryogenic temperatures ranging from <NUM> Kelvin (K) to <NUM>. <CIT> discloses a method for filling a pressure vessel provided for a cryogenic storage medium, such as hydrogen.

A full and enabling disclosure of the preferred embodiments, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended Figures, in which:.

The figures are not to scale. Instead, the thickness of the layers or regions may be enlarged in the drawings. In general, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. As used in this patent, stating that any part (e.g., a layer, film, area, region, or plate) is in any way on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, indicates that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween. Connection references (e.g., attached, coupled, connected, joined, detached, decoupled, disconnected, separated, etc.) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As used herein, the term "decouplable" refers to the capability of two parts to be attached, connected, and/or otherwise joined and then be detached, disconnected, and/or otherwise non-destructively separated from each other (e.g., by removing one or more fasteners, removing a connecting part, etc.). As such, connection/disconnection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. Stating that any part is in "contact" with another part means that there is no intermediate part between the two parts.

Descriptors "first," "second," "third," etc., are used herein when identifying multiple elements or components which may be referred to separately.

The operations of systems for refueling a hydrogen-powered vehicle (e.g., aircraft, cars, trucks, ships, etc.) with liquid hydrogen (LH2) include an LH2 supply tank (e.g., on a supply truck/trailer) often of the same structure or functionality as onboard LH2 tank(s). The refueling system uses a pump and other apparatus to provide the hydrogen aircraft with the LH2 at a correct temperature and saturated pressure. Some vehicles or machines, such as other hydrogen aircraft, spacecraft, municipal power, etc. use cryo-compressed hydrogen (CcH2) tank(s) instead of LH2 tank(s) to store the hydrogen fuel for power generation. In some examples used herein, "cryo-compressed hydrogen" refers to hydrogen (e.g., LH2, gaseous hydrogen (GH2), hydrogen vapor, etc.) that has been compressed to pressures greater than a critical point of hydrogen (e.g., <NUM> bar) while at cryogenic temperatures (e.g. <NUM> to <NUM>). For example, upon reaching such pressures and temperatures, LH2 phase shifts into a supercritical fluid and can then be referred to as CcH2. Some hydrogen aircraft include onboard CcH2 tank(s) instead of onboard LH2 tank(s) so that a cryogenic pump is not included on the aircraft. Rather, the CcH2 is already highly compressed (e.g., up to <NUM> bar) in the onboard CcH2 tank(s) and can be provided to the engines for combustion via a pressure-driven fuel supply system. Including the onboard CcH2 tank(s) without the cryogenic pump can save weight and space on the hydrogen aircraft compared to the other hydrogen aircraft that include the onboard LH2 tank(s) and the LH2 pump. The examples disclosed herein include systems for refueling CcH2 tank(s) onboard a vehicle (e.g., a hydrogen aircraft, a spacecraft, or another vehicle that uses CcH2 fuel) or integrated into a power generation facility (e.g., a municipal power plant that uses CcH2 fuel) up to a target pressure and temperature such that the target pressure and temperature are achieved together and the CcH2 does not convert back into LH2.

In the examples disclosed herein, the CcH2 refueling systems can be used to refuel onboard CcH2 tank(s) and/or other example CcH2 tank(s), vessel(s), and/or container(s) up to the target pressure while controlling the temperature in the example CcH2 tanks. During a refuel process with the example CcH2 refueling systems, a reverse Joule-Thomson effect of hydrogen causes the temperature of CcH2 in portions of the CcH2 refueling systems and in the CcH2 tanks to decrease. In thermodynamics, the Joule-Thomson effect describes a temperature change of a real gas that occurs while the real gas flows from a high pressure area to a low pressure area through an orifice, otherwise known as throttling. At room temperature and with constant enthalpy, hydrogen warms upon expansion due to the Joule-Thomson effect. However, at cryogenic temperatures (e.g., CcH2 temperatures of <NUM>, <NUM>, <NUM>, etc.), the Joule-Thomson effect of hydrogen reverses causing hydrogen to cool upon expansion. In the examples disclosed herein, the CcH2 refueling systems include valves (e.g., proportional valves, regulator valves, cryogenic valves, etc.) that throttle the CcH2 fuel causing expansion and cooling of the CcH2 downstream of the valves and in the example CcH2 tanks. The examples disclosed herein include CcH2 refueling systems that introduce gaseous hydrogen to the CcH2 fuel during the refuel process to controllably warm the CcH2 fuel and counteract the reverse Joule-Thomson effect of CcH2.

The example CcH2 refueling systems disclosed herein include a CcH2 refueler, a CcH2 source, and a supercritical hydrogen (sH2) source to refuel a CcH2 tank and/or vessel (e.g., onboard an aircraft, onboard a spacecraft, integrated into a municipal power system, etc.) up to a target pressure at a target temperature. The example CcH2 source can include a cryogenic pump to cryogenically compress LH2 into CcH2. Additionally or alternatively, the example CcH2 source can include or a CcH2 supply tank. The example sH2 source can include a vaporizer to warm a portion of the CcH2 fuel up to near ambient temperatures (e.g., <NUM> when the ambient temperature is <NUM>, or <NUM> when the ambient temperature is <NUM>). Additionally or alternatively, the example sH2 source can include hydrogen storage tanks capable of storing hydrogen at high pressures (e.g., <NUM> bar or greater) and near ambient temperatures such that the sH2 can be kept in the supercritical state. In the examples disclosed herein, the CcH2 refueler includes a mixing tank to combine CcH2 from the CcH2 source and sH2 from the sH2 source prior to fueling the CcH2 tank with the CcH2 fuel. The example CcH2 refueler controller causes an adjustment to the flowrate of sH2 entering the mixing tank to control the temperature of the CcH2 fuel being supplied to the CcH2 tank. For example, when the temperature of the CcH2 tank does not satisfy a target temperature (e.g., when the temperature falls below <NUM>), then the CcH2 refueler controller causes the flowrate of sH2 into the mixing tank to increase until the temperature of the CcH2 tank satisfies the target temperature or until a temperature of the mixing tank satisfies the target temperature (e.g., or a target temperature of the mixing tank).

In some examples used herein, "saturated pressure" refers to a vapor pressure acting on the walls of a tank (e.g., a LH2 supply tank and/or an onboard LH2 tank) and the surface of a liquid (e.g., LH2) within the tank when the vapor is in equilibrium with the liquid. That is, when the temperature of the liquid remains relatively constant and does not increase enough to cause further evaporation, the vapor is considered to be in equilibrium with the liquid. The example onboard CcH2 tank <NUM> is referred to store CcH2 at a "pressure" rather than at a "saturated pressure" because the CcH2 within the onboard CcH2 tank <NUM> is a supercritical fluid with no LH2 present.

In some examples used herein, "upstream" and "downstream" refer to the relative direction with respect to fluid flow in a fluid pathway. The term "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction to which the fluid flows. For example, if a system includes a pump and a flowmeter, and the flowmeter measures a flowrate of fluid exiting the pump, then the flowmeter is downstream of the pump, and the pump is upstream of the flowmeter.

In some examples used herein, "including" and "comprising" (and all forms and tenses thereof) are used herein to be open ended terms.

For the figures disclosed herein, identical numerals indicate the same elements throughout the figures. The example illustration of <FIG> is a block diagram representing a prior LH2 refueling system <NUM>. As shown in <FIG>, the LH2 refueling system <NUM> ("system <NUM>") includes an example LH2 supply tank <NUM>, an example hydrogen aircraft <NUM>, an example onboard LH2 tank <NUM>, an example proportional valve <NUM>, an example flowmeter <NUM>, and an example refueler valve <NUM> connected in series via example vacuum-jacketed (VJ) flowlines <NUM> and example flexible VJ flowline(s) <NUM>. In general, the system <NUM> is configured to supply LH2 to the onboard LH2 tank <NUM> at a same temperature and pressure as is in the LH2 supply tank <NUM>.

The example system <NUM> illustrated in <FIG> includes the LH2 supply tank <NUM> to provide LH2 fuel to the example hydrogen aircraft <NUM> at a known temperature and pressure. The example LH2 supply <NUM> tank can be included on a trailer of a LH2 supply truck for mobile delivery of the fuel. In some examples, the LH2 supply tank <NUM> is stationary and positioned near an expected docking area of the aircraft <NUM>. During storage, the LH2 temperature may increase, some LH2 may boil-off/evaporate, and, therefore, pressure in the LH2 supply tank <NUM> may increase. In some examples, the LH2 supply <NUM> includes venting mechanisms to release hydrogen vapor and reduce pressure build up caused from boil-off. The example LH2 supply tank <NUM> can also include insulating materials and/or insulating structures (e.g., a vacuum layer between an inner shell and an outer shell) to maintain cryogenic temperatures of the LH2 and limit excessive boil-off.

The example system <NUM> illustrated in <FIG> includes the onboard LH2 tank <NUM> to store LH2 fuel on the example aircraft <NUM>. In some examples, the onboard LH2 tank <NUM> of the example aircraft <NUM> includes similar or same structures and functionalities as the LH2 supply tank <NUM>. The example onboard LH2 tank <NUM> includes two different states of hydrogen (e.g., LH2 and GH2), and gradual evaporation of the LH2 causes the saturated pressure of the onboard LH2 tank <NUM> to increase. In some examples, the onboard LH2 tank <NUM> includes one or more venting mechanisms to control rising saturated pressures due to boil-off and to satisfy a saturated pressure threshold of the onboard LH2 tank <NUM>.

In some examples, the aircraft <NUM> includes a cryogenic pump (e.g., an LH2 pump) to supply LH2 fuel to other components of the fuel supply line (e.g., heat exchangers, compressors, buffer tanks, etc.) and ultimately to the combustor(s) of the engine(s). Since the saturated pressure in the example onboard LH2 tank <NUM> has a limited range (e.g., one bar to ten bar), the internal saturated pressure is not enough to drive the LH2 fuel through the fuel supply line. Hence, the cryogenic pump is included with the example onboard LH2 tank <NUM> to send the LH2 to a heat exchanger and/or a compressor causing a phase change to GH2. Then, the GH2 can be further supplied, via the cryogenic pump and/or another pump, to the combustor(s) as fuel.

The example system <NUM> illustrated in <FIG> includes the proportional valve <NUM> to control the flowrate of the LH2 fuel through the system <NUM>. In some examples, the proportional valve <NUM> is a servo valve that can be hydraulically or electronically actuated via a signal (e.g., digital or analog) to generate an effective outlet area. Standard control valves generally operate in fully open or fully closed states of flow. The example proportional valve <NUM> can adjust a position of a spool to control the flowrate of the LH2 through one or more outlet flowlines. The pressure of the LH2 upstream and downstream of the example proportional valve <NUM> remains unchanged but the mass flowrate and volumetric flowrate of the LH2 can be varied depending on a desired refuel rate. The example proportional valve <NUM> can operate at working temperatures lower than <NUM> and can regulate flow of cryogenic fluids (e.g., liquefied natural gas, liquid oxygen, LH2, etc.). The example proportional valve <NUM> is constructed to thermally insulate the LH2 fuel during transmission to prevent or inhibit boil-off. In some examples, the proportional valve <NUM> is connected to upstream component(s) and/or downstream component(s) via one or more VJ flowlines <NUM> and/or one or more flexible VJ flowlines <NUM>.

The example system <NUM> illustrated in <FIG> includes the flowmeter <NUM> to detect the flowrate of LH2 through the system <NUM>. In some examples, the flowmeter <NUM> is a volumetric flowmeter that can detect the volume of LH2 that flows per unit of time. In some examples, the flowmeter <NUM> measures the velocity of the flow of the LH2 and multiplies the velocity by the cross-sectional area of the flowline where the flowmeter <NUM> is located. The example flowmeter <NUM> can also determine a total volume of LH2 currently supplied to the onboard LH2 tank <NUM>. For example, the flowmeter <NUM> measures a current flowrate of the LH2, and, in response to the current flowrate not satisfying a target flowrate, the system <NUM> causes the proportional valve <NUM> to increase the effective outlet area. In another example, the flowmeter <NUM> determines a current total volume of LH2 in the onboard LH2 tank <NUM>, and, in response to the current total satisfying a target total volume, the system <NUM> ends the refueling process of the LH2 fuel.

The example system <NUM> illustrated in <FIG> includes the refueler valve <NUM> to start or stop the flow of LH2 to the onboard LH2 tank <NUM>. The example refueler valve <NUM> is a cryogenic valve that can operate at working temperatures lower than <NUM> and can regulate flow of cryogenic fluids. The example refueler valve <NUM> is constructed to thermally insulate the LH2 fuel during transmission to prevent or inhibit boil-off. In some examples, the refueler valve <NUM> is connected to upstream component(s) and/or downstream component(s) via one or more VJ flowlines <NUM> and/or one or more flexible VJ flowlines <NUM>.

The example refueler valve <NUM> illustrated in <FIG> can be a gate valve, butterfly valve, solenoid valve, etc. manually operated or electronically actuated. In some examples, the refueler valve <NUM> operates in either to opened or to closed states to fully allow or fully prevent flow of fuel. In some examples, the refueler valve <NUM> is a shut-off valve to quickly terminate flow to the onboard LH2 tank <NUM> such that the onboard LH2 tank <NUM> does not overfill. In some examples, the refueler valve <NUM> is a proportional valve that adjusts the outlet flowrate based on fluctuating upstream pressures, temperatures, densities, etc..

The example system <NUM> illustrated in <FIG> includes the VJ flowlines <NUM> and the flexible VJ flowline(s) <NUM> to connect the components of the system <NUM>. In some examples, the VJ flowlines <NUM> illustrated in the figures disclosed herein are rigid, flexible, and/or a combination thereof. The example VJ flowlines <NUM> and flexible VJ flowline(s) <NUM> are designed with an inner line, an outer line, and an intermediary layer. The example intermediary layer can include multiple alternating layers of a heat barrier and a nonconductive spacer to form gap between the inner line and the outer line. The example intermediary layer can be depressurized using a vacuum pump to create a static vacuum shield. The example vacuum shield can safeguard the cryogenic fuel from heat transfer caused by radiation, conduction, and/or convection. Thus, the VJ flowlines <NUM> and the flexible VJ flowline(s) <NUM> are used to transport the example LH2 in the example system <NUM> to maintain cryogenic temperatures and to prevent or inhibit boil-off. In some examples, the VJ flowlines <NUM> and flexible VJ flowline(s) <NUM> include VJ valves, vapor vents, vapor vent heaters, VJ manifolds, etc., to further control the temperatures of the LH2 fuel.

As described previously, the example onboard LH2 tank <NUM> is located on the example hydrogen aircraft <NUM> to store LH2 fuel for hydrogen-powered turbine engine(s). The example hydrogen-powered turbine engine(s) combust a mixture of compressed hydrogen and compressed air and/or oxygen to generate thrust. The example aircraft <NUM> may also include a cryogenic pump (e.g., an LH2 pump) to drive a fuel supply system and compress the LH2 leaving the onboard LH2 tank <NUM>. In the examples disclosed herein, CcH2 refueling systems are used to supply an example vehicle (e.g., an aircraft, car, truck, etc.) with CcH2 fuel without including the cryogenic pump onboard the example vehicle, thus conserving weight and space.

The example system <NUM> illustrated in <FIG> refuels the hydrogen aircraft <NUM> with LH2 at conditions similar to the temperature and pressure within the LH2 supply tank <NUM>. That is, the system <NUM> cannot control a pressure or temperature of the LH2 fuel during a refueling process of the aircraft <NUM>. Thus, the system <NUM> cannot increase the LH2 fuel's density relative to the density in the LH2 supply tank <NUM>, nor can the system <NUM> increase the mass of fuel supplied to the aircraft <NUM>. Furthermore, the system <NUM> can only refuel the onboard LH2 tank <NUM> with LH2 fuel. Since the system <NUM> refuels the example hydrogen aircraft <NUM> with LH2 fuel, the aircraft <NUM> includes an onboard cryogenic pump to pressurize a fuel system and provide LH2 fuel to the engines. In the examples disclosed herein, CcH2 refueling systems can refuel an onboard hydrogen tank with CcH2 fuel up to a pressure threshold and at a controlled temperature. Thus, the example CcH2 refueling systems disclosed herein can increase a density of the CcH2 during the refuel process and, thus, increase the mass of CcH2 fuel supplied relative to the mass of LH2 fuel the system <NUM> can supply. Furthermore, the example CcH2 refueling systems disclosed herein can supply CcH2 at high pressures (e.g., <NUM> bar to <NUM> bar) such that the pressure in the onboard hydrogen tank is enough to pressurize a fuel system to provide CcH2 fuel to the engines without the use of a cryogenic pump. Thus, the example CcH2 systems disclosed herein can control a mass of CcH2 fuel supplied to a hydrogen vehicle (e.g., a hydrogen aircraft), control a temperature of the CcH2 fuel (e.g., to prevent a phase shift back to LH2), and can pressurize an onboard hydrogen tank such that an onboard cryogenic pump is not included, and onboard space and weight is conserved.

<FIG> illustrates a first example CcH2 refueling system <NUM> ("system <NUM>") to supply CcH2 fuel to an example vehicle up to the target onboard pressure while also achieving a controlled and/or consistent temperature. The example system <NUM> includes the example LH2 supply tank <NUM>, the example proportional valves <NUM>, the example flowmeter <NUM>, the example refueler valve <NUM>, the example VJ flowlines <NUM>, and the example flexible VJ flowline(s) <NUM> as illustrated in <FIG>. As illustrated in <FIG>, the example system <NUM> further includes an example CcH2 refueler <NUM>, an example hydrogen aircraft <NUM>, an example onboard CcH2 tank <NUM>, an example first pressure sensor <NUM>, an example first temperature sensor <NUM>, and an example transfer pump <NUM>. The example CcH2 refueler <NUM> of the example system <NUM> includes an example cryogenic pump <NUM>, an example pump motor <NUM>, an example mixing tank <NUM>, an example second pressure sensor <NUM>, an example second temperature sensor <NUM>, an example vaporizer <NUM>, an example check valve <NUM>, an example defueler valve <NUM>, an example split valve <NUM>, example hydrogen containers <NUM>, an example CcH2 refueler controller <NUM>, example processor circuitry <NUM>, example memory <NUM>, example flowrate loop circuitry <NUM>, example pressure loop circuitry <NUM>, example temperature loop circuitry <NUM>, and example position loop circuitry <NUM>. For the figures disclosed herein, a portion of the flowlines are labeled as VJ flowlines <NUM>. However, some or all of the flowlines illustrated in the figures disclosed herein may be the VJ flowlines <NUM>, except ones labeled as the flexible VJ flowline <NUM>.

The example system <NUM> illustrated in <FIG> includes the example hydrogen aircraft <NUM> as the vehicle to be refueled with CcH2 fuel via the example CcH2 refueler <NUM>. Although <FIG> depicts the hydrogen aircraft <NUM>, a different vehicle (e.g., a hydrogen-powered car, truck, boat, ship, helicopter, rocket engine, etc.) or standalone CcH2 tank may be refueled with CcH2 fuel via the system <NUM>. In some examples, the hydrogen aircraft <NUM> is to be refueled after a flight in which a portion of the CcH2 fuel (e.g., some, all, a majority of, etc.) has been used to provide energy to the hydrogen aircraft <NUM>. Thus, a portion of unused CcH2 fuel may be included in the aircraft <NUM>, and the example CcH2 refueler <NUM> can defuel the aircraft <NUM> prior to the refueling process. The example hydrogen aircraft <NUM> includes fuel lines, pumps, valves, etc. to supply the fuel to hydrogen engine(s). Once at the engine(s), combustor(s) can oxidize and burn the hydrogen fuel, which causes an exothermic reaction, provides energy to the turbines, and generates thrust.

The example system <NUM> illustrated in <FIG> includes the example onboard CcH2 tank <NUM> to store the CcH2 fuel on the hydrogen aircraft <NUM>. The example onboard CcH2 tank <NUM> can store CcH2 at pressures higher than the pressure limits of LH2 tanks (e.g., the LH2 supply tank <NUM> and the onboard LH2 tank <NUM> of <FIG>). For example, the onboard CcH2 tank <NUM> stores CcH2 at pressures ranging from <NUM> bar to <NUM> bar with a factor of safety (e.g., <NUM>, <NUM>, <NUM>, etc.) included. In contrast, the example onboard LH2 tank <NUM> can store LH2 at saturated pressures ranging from one bar to ten bar with the same or a similar factor of safety. The CcH2 inside the example onboard CcH2 tank <NUM> does not experience boil-off like the LH2 inside LH2 storage tanks (e.g., the LH2 supply tank <NUM> and the onboard LH2 tank <NUM> of <FIG>) because the example onboard CcH2 tank <NUM> includes supercritical CcH2. Therefore, instead of including a venting mechanism, the example onboard CcH2 tank <NUM> can release CcH2 fuel into a fuel supply system to control internal pressure of the onboard CcH2 tank <NUM>. Unlike the example onboard LH2 tank <NUM>, as described previously, the CcH2 fuel can be driven through the fuel supply system and components (e.g., heat exchangers, compressors, buffer tanks, etc.) via the internal pressure (e.g., <NUM> bar to <NUM> bar) of the onboard CcH2 tank <NUM> alone, without reliance on an onboard LH2 pump. As the onboard CcH2 tank <NUM> releases CcH2, the internal temperature can increase due to thermal losses, which can be desirable for maintaining a constant pressure of the onboard CcH2 tank <NUM> (e.g., isobaric) as the CcH2 fuel is released. In some examples, when the thermal losses are not enough to keep the onboard CcH2 tank <NUM> isobaric, the onboard CcH2 tank <NUM> includes a heater to further increase the internal temperature and, in turn, keep the internal pressure constant.

In some examples, the onboard CcH2 tank <NUM> can store CcH2 at a density similar to the density of LH2 in the example onboard LH2 tank <NUM>, but at different pressures and temperatures. For example, the onboard CcH2 tank <NUM> stores CcH2 at a density of <NUM>/m<NUM> at a pressure of <NUM> bar and a temperature of <NUM>, while the onboard LH2 tank <NUM> stores the LH2 at the same density but at a saturated pressure of <NUM> bar and a temperature of <NUM>. In some examples, the onboard CcH2 tank <NUM> is a dual wall cryostat including an inner cryovessel and an outer vacuum vessel. The example cryovessel of the onboard CcH2 tank <NUM> includes a thicker wall than that of the example onboard LH2 tank <NUM>, but the example vacuum vessel of the onboard CcH2 tank <NUM> is of the same wall thickness as that of the onboard LH2 tank <NUM> because the vacuum vessels of the two tanks <NUM>, <NUM> are designed for the same pressure differential (e.g., <NUM> atmosphere(atm), <NUM> atm, <NUM> atm, etc.). In some examples, both the cryovessel and the vacuum vessel of the onboard CcH2 tank <NUM> are type-<NUM> vessels, which include an aluminum liner fully wrapped with a fiber-resin composite.

The example system <NUM> illustrated in <FIG> includes the example first pressure sensor <NUM> and the example first temperature sensor <NUM> to monitor the pressure and temperature of the CcH2 inside the onboard CcH2 tank <NUM> during the refueling process. In some examples, the first pressure sensor <NUM> is a cryogenic pressure transducer that can operate in temperatures ranging from <NUM> to <NUM> and pressures ranging from <NUM> bar to <NUM> bar. The example first temperature sensor <NUM> can be a cryogenic silicon sensor, a silicon diode, a sheathed thermocouple, platinum resistance sensor, cryogenic temperature monitor, etc. In some examples, more than one first pressure sensor <NUM> and/or more than one first temperature sensor <NUM> are included in the onboard CcH2 tank <NUM>. The example first pressure sensor <NUM> and the example first temperature sensor <NUM> are coupled to the CcH2 refueler <NUM> via a wired or wireless connection to transmit current pressure and temperature measurements of the CcH2 stored in the onboard CcH2 tank <NUM>. Further details on how the example CcH2 refueler <NUM> uses the pressure and temperature measurements are described below.

The example system <NUM> illustrated in <FIG> includes the example transfer pump <NUM> to transmit LH2 from the example LH2 supply tank <NUM> to the example CcH2 refueler <NUM>. The LH2 supply tank <NUM> can include LH2 at pressures slightly above atmospheric pressure (e.g., three bar, four bar, five bar, etc.). The example transfer pump <NUM> can increase the pressure of the LH2 (e.g., to four bar, five bar, six bar, etc.) to drive the LH2 downstream to the example cryogenic pump <NUM>. The example transfer pump <NUM> as illustrated in <FIG> is a submerged cryogenic pump within the LH2 supply tank <NUM>. In some examples, the transfer pump <NUM> is externally connected to the LH2 supply tank <NUM>. The example transfer pump <NUM> can be an electronically and/or hydraulically driven cryogenic centrifugal pump. In some examples, the transfer pump <NUM> provides variable flow speeds of LH2 via a control panel on the LH2 supply tank <NUM>. In some examples, the transfer pump <NUM> includes a gearbox that provides fixed or variable flow speeds of LH2 to the CcH2 refueler <NUM>.

The example system <NUM> illustrated in <FIG> includes the example CcH2 refueler <NUM> to refuel the example onboard CcH2 tank <NUM> with CcH2 up to a target pressure while simultaneously maintaining a target temperature. The example CcH2 refueler <NUM> monitors a first temperature in the onboard CcH2 tank <NUM> and regulates a second temperature in the mixing tank <NUM> based on the first temperature. As shown in the figures and disclosed herein, the CcH2 refueler <NUM> sends sH2 to the mixing tank <NUM> to control the temperature of the CcH2 in the mixing tank <NUM> and, by extension, the temperature of the CcH2 in the onboard CcH2 tank <NUM>.

The example system <NUM> illustrated in <FIG> includes the example cryogenic pump <NUM> to cryogenically compress the LH2 from the LH2 supply tank <NUM> and to drive CcH2 to the mixing tank <NUM> and the proportional valve <NUM>. In some examples, the cryogenic pump <NUM> includes a suction adapter, a cold end piston, and the example pump motor <NUM>. An intake line is connected to the transfer pump <NUM> to transport LH2 into the suction adapter of cryogenic pump <NUM>. In the suction adapter, the LH2 temperature rises and a portion of the LH2 evaporates into GH2. The example cryogenic pump <NUM> further includes a return line leading from the suction adapter back to the LH2 supply tank <NUM> to recycle the GH2 and to ensure there is always a net positive suction head (NPSH) in the cryogenic pump <NUM>. The NPSH facilitates pressure-driven flow of LH2 into the cryogenic pump <NUM> and allows the pump motor <NUM> to freely adjust the rate and amount of CcH2 leaving the cryogenic pump <NUM>. The example cryogenic pump <NUM> includes the cold end piston to compress the LH2 from an input pressure (e.g., one bar to ten bar) to an output pressure (e.g., <NUM> bar to <NUM> bar) at cryogenic temperatures (e.g., <NUM>, <NUM>, <NUM>, etc.). In some examples, one cold end piston is used in the cryogenic pump <NUM> to vary the output pressure (e.g., between <NUM> bar and <NUM> bar). In some examples, multiple cold end pistons are included in the cryogenic pump <NUM> and are used in series to vary the output pressure. As mentioned previously, by increasing the pressure of the LH2 at cryogenic temperatures, the LH2 converts/shifts/phases to a supercritical state, and the fuel leaving the cryogenic pump <NUM> can be referred to as CcH2. The example output CcH2 has a similar temperature (e.g., within <NUM>, <NUM>, <NUM>, etc.) and a similar density (e.g., within <NUM>/m<NUM>, <NUM>/m<NUM>, <NUM>/m<NUM>, <NUM>/m<NUM>, etc.) as the input LH2.

The example system <NUM> illustrated in <FIG> includes the example motor <NUM> to accelerate the CcH2 out of the cryogenic pump <NUM> and to adjust the flowrate of the CcH2 through the system <NUM>. As mentioned previously, the example flowmeter <NUM> can measure the volumetric flowrate and/or the mass flowrate of the CcH2 through the system <NUM>. In some examples, the system <NUM> is to refuel the onboard CcH2 tank <NUM> in a timeframe threshold (e.g., <NUM> minutes, <NUM> minutes, one hour, etc.). When, for example, the onboard CcH2 tank <NUM> has a volume of <NUM><NUM>, and the refuel process has a <NUM> minute threshold, then the pump motor <NUM> is to refuel the onboard CcH2 tank <NUM> at a desired volumetric flowrate of at least <NUM> cubic meters per second (m<NUM>/s). In some examples, and discussed in further detail below, the CcH2 refueler controller <NUM> detects, via the flowmeter <NUM>, when the CcH2 is flowing at a rate less than the desired flowrate. In response, the example CcH2 refueler controller <NUM> sends a signal to the pump motor <NUM> to increase the operational speed of the motor and, in turn, the flowrate of the CcH2.

The example system <NUM> illustrated in <FIG> includes the example mixing tank <NUM> to combine the CcH2 with varying quantities of the sH2 to adjust the temperature of the CcH2 in the onboard CcH2 tank <NUM>. The example mixing tank <NUM> is a cryo-compressed tank with a same or a similar structural design as that of the onboard CcH2 tank <NUM> described previously. In some examples, the mixing tank <NUM> has a smaller internal volume than the onboard CcH2 tank <NUM> (e.g., <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, etc.). The pressure inside the example mixing tank <NUM> adjusts according to the pressure output of the cryogenic pump <NUM> and is typically held at pressures slightly higher (e.g., one bar, two bar, etc.) than pressures within the onboard CcH2 tank <NUM>. Thus, positive pressure drives the flow of CcH2 from the mixing tank <NUM> downstream to the onboard CcH2 tank <NUM>.

The example system <NUM> illustrated in <FIG> includes the example second pressure sensor <NUM> and the example second temperature sensor <NUM> to send pressure and temperature measurements to the CcH2 refueler controller <NUM> (described in greater detail below) via electrical signals. For example, when the temperature sensor <NUM> sends a temperature reading to the CcH2 refueler controller <NUM> indicating that the temperature of the CcH2 in the mixing tank <NUM> is below a temperature threshold (e.g., <NUM>), then the CcH2 refueler controller <NUM> increases the flow of sH2 into the mixing tank <NUM>, thus increasing the temperature of the CcH2 in the mixing tank <NUM> and the onboard CcH2 tank <NUM>. The example second pressure sensor <NUM> and the example second temperature sensor <NUM> can be of a same or similar type as the first pressure sensor <NUM> and the first temperature sensor <NUM> described previously.

The example system <NUM> illustrated in <FIG> includes the vaporizer <NUM> to warm the CcH2 to high-pressure sH2, which is mixed with the CcH2 in the mixing tank <NUM>. The example vaporizer <NUM> can be a cryogenic vaporizer that uses fins to transfer heat from surrounding ambient air to the CcH2 flowing from the proportional valve <NUM>. When the example vaporizer <NUM> increases the CcH2 temperature, the pressure of the sH2 remains substantially the same due to the high density of CcH2 (e.g., <NUM>/m<NUM> or greater). The hydrogen leaving the example vaporizer <NUM> is in the same supercritical state as the upstream CcH2 but is no longer at cryogenic temperatures. Therefore, as mentioned previously, the hydrogen downstream of the vaporizer <NUM> and upstream of the mixing tank <NUM> is referred to as supercritical hydrogen (sH2). When the CcH2 heats up in the supercritical state (e.g., due to the vaporizer <NUM>), the hydrogen gas molecules can expand within the same volume at the same pressure. Therefore, the sH2 downstream of the vaporizer <NUM> is the same pressure as the CcH2 upstream of the vaporizer <NUM> and in the mixing tank <NUM>. Thus, the sH2 can flow freely to the mixing tank <NUM> and combine with the CcH2.

In some examples, after the refueling process is over, the temperature of the CcH2 downstream of the vaporizer <NUM> (e.g., in the mixing tank <NUM>) can increase over time. During that time, pressures within the CcH2 refueler <NUM> and downstream of the cryogenic pump <NUM> can increase. Additionally or alternatively, during the refueling process, CcH2 can build up and/or solidify in the vaporizer <NUM> creating a blockage of flow (e.g., an ice block) and an increase of pressure upstream of the vaporizer <NUM>. The example system <NUM> includes the example check valve <NUM> to prevent the pressure directly downstream of the cryogenic pump <NUM> from exceeding a pressure threshold. For example, if the pressure downstream of the vaporizer <NUM> is <NUM> bar prior to the refuel process, and if the check valve <NUM> is not included, then the cryogenic pump <NUM> has to provide a startup output pressure of at least <NUM> bar to drive the flow downstream. This can cause the flow to reverse upon startup, which can damage the cryogenic pump <NUM> or cause the CcH2 to flow upstream into the LH2 supply tank <NUM>. The example check valve <NUM> allows the CcH2 fluid to flow in a first direction (e.g., from the proportional valve <NUM> to the vaporizer <NUM>) but not in a second direction, opposite from the first direction. In some examples, the check valve <NUM> includes a body, an inlet port, and an outlet port and works automatically without the CcH2 refueler controller <NUM> operating the check valve <NUM> or causing a mechanism in the valve to actuate. The example check valve <NUM> can be designed with a reseal pressure specification that prevents a sufficiently significant back pressure from forming. For example, the check valve <NUM> is designed to close off, inhibit, and/or prevent the reversal of CcH2 flow when the pressure differential between the inlet and outlet ports satisfies a differential threshold (e.g., a pressure differential of one bar, <NUM> bar, <NUM> bar, etc.).

In some examples, the system <NUM> is refueling the aircraft <NUM> after a flight in which a portion (e.g., <NUM>%, <NUM>%, <NUM>%, etc.) of the CcH2 fuel has been used. As previously mentioned, the example onboard CcH2 tank <NUM> is isobaric and may deliver the CcH2 fuel to the engines while maintaining a constant pressure. Therefore, the example onboard CcH2 tanks <NUM> may be above a preliminary pressure threshold prior to the refueling process. The preliminary pressure threshold (e.g., <NUM> bar, <NUM> bar, <NUM> bar, etc.) is the pressure that the onboard CcH2 tank <NUM> is to have before the refueling process can begin. So, in some example use cases, the refuel process includes defueling unused CcH2 from the example aircraft <NUM> to reduce the pressure in the onboard CcH2 tank <NUM> prior to refueling.

The example system <NUM> illustrated in <FIG> includes the example defueler valve <NUM> to release unused CcH2 from the onboard CcH2 tank <NUM> prior to refueling the aircraft <NUM>. The example defueler valve <NUM> may open in response to a command from the pressure loop circuitry <NUM> and/or the position loop circuitry <NUM> based on the onboard pressure not satisfying the preliminary pressure threshold. For example, if the preliminary pressure threshold is <NUM> bar, and the onboard pressure prior to refueling is <NUM> bar, then the defueler valve <NUM> opens to facilitate flow to a lower downstream pressure area (e.g., the mixing tank <NUM>, the hydrogen containers <NUM>, open atmosphere, etc.). In some examples, the defueler valve <NUM> is a proportional valve similar to the proportional valve <NUM> of <FIG> and <FIG> that allows for variable outlet flowrates given fluctuating inlet pressures, temperatures, densities, etc. In some examples, the defueler valve <NUM> is a cryogenic valve similar to the refueler valve <NUM> of <FIG> and <FIG> that can switch from fully open to fully closed some time (e.g., two times, five times, ten times, etc.) faster than the example proportional valve <NUM>.

The example system <NUM> illustrated in <FIG> includes the example split valve <NUM> to direct or divert CcH2 from the onboard CcH2 tank <NUM> to the mixing tank <NUM>, the hydrogen containers <NUM>, and/or to a secondary destination (e.g., open atmosphere, another hydrogen storage tank, the LH2 supply tank <NUM>, etc.). In some examples, the split valve <NUM> directs or diverts the CcH2 to the secondary destination when the mixing tank <NUM> and the hydrogen containers <NUM> are at a higher pressure than the onboard CcH2 tank <NUM> and when the pressure of the onboard CcH2 tank <NUM> is higher than the preliminary pressure threshold.

In some examples, the CcH2 refueler <NUM> is to refuel the example aircraft <NUM> after landing and/or defueling, at which point the onboard CcH2 tank <NUM> may contain a small portion of CcH2 (e.g., <NUM>% capacity, <NUM>% capacity, etc.) at high pressures (e.g., <NUM> bar to <NUM> bar) and high temperatures (e.g., <NUM>, <NUM>, etc.). Prior to refueling, the example CcH2 refueler controller <NUM> determines whether the onboard pressure satisfies the preliminary pressure threshold (e.g., <NUM> bar, <NUM> bar, <NUM> bar, etc.). When the example onboard pressure is greater than the preliminary pressure threshold, then the CcH2 refueler <NUM> causes the defueler valve <NUM> to open to a desired flowrate. In some examples, when the pressure of the onboard CcH2 tank <NUM> does not satisfy the pressure threshold and when the pressure of the mixing tank <NUM> is less than the pressure of the onboard CcH2 tank <NUM>, then the split valve <NUM> directs/diverts the CcH2 to the mixing tank <NUM>. In some examples, when the pressure of the onboard CcH2 tank <NUM> does not satisfy the pressure threshold and when the pressure of the mixing tank <NUM> is greater than or equal to the pressure of the onboard CcH2 tank <NUM>, then the split valve <NUM> directs/diverts the CcH2 from the onboard CcH2 tank <NUM> to the hydrogen containers <NUM> and/or another secondary destination (e.g., atmosphere). The example hydrogen containers <NUM> illustrated in <FIG> can be at low pressures (e.g., two bar, five bar, etc.) or atmospheric pressures (e.g., <NUM> psi, one bar, etc.) prior to defueling/refueling the example aircraft <NUM>. In some examples, the hydrogen containers <NUM> are at high enough pressures (e.g., <NUM> bar, <NUM> bar, etc.) that a compressor is included to drive the onboard CcH2 into the hydrogen containers <NUM>. When included in the example system <NUM>, the compressor is located upstream of the hydrogen containers <NUM> and downstream of the split valve <NUM>.

The example system <NUM> illustrated in <FIG> includes the CcH2 refueler controller <NUM> to automatically control and to facilitate operation of the CcH2 refueler <NUM>. In some examples, the CcH2 refueler controller <NUM> is a closed-loop control system including the processor circuitry <NUM> and the memory <NUM>. The example processor circuitry <NUM> includes the example flowrate loop circuitry <NUM>, the example pressure loop circuitry <NUM>, the example temperature loop circuitry <NUM>, and the example position loop circuitry <NUM>. The example processor circuitry <NUM> can instantiate (e.g., create an instance of, bring into being for any length of time, materialize, implement, etc.) the CcH2 refueler controller <NUM> of <FIG>. In some examples, the processor circuitry <NUM> is a central processing unit executing instructions. Additionally or alternatively, the processor circuitry <NUM> can be an application-specific integrated circuitry (ASIC) or a field-programmable gate array (FPGA) structured to perform operations corresponding to the instructions. It should be understood that some or all of the processor circuitry <NUM> of <FIG> can, thus, be instantiated at the same or different times. Some or all of the processor circuitry <NUM> can be instantiated, for example, in one or more threads executing concurrently on hardware and/or in series on hardware. Moreover, in some examples, one or more virtual machines and/or containers executing on a microprocessor can implement some or all of the processor circuitry <NUM> of <FIG>. The example flowrate loop circuitry <NUM>, the example pressure loop circuitry <NUM>, the temperature loop circuitry <NUM>, and the position loop circuitry <NUM> illustrated in <FIG> are integrated on the processor circuitry <NUM>. In some examples, the flowrate loop circuitry <NUM>, the pressure loop circuitry <NUM>, the temperature loop circuitry <NUM>, and/or the position loop circuitry <NUM> are integrated on separate circuitry (e.g., processor circuitry, FPGA, ASIC, microprocessor, etc.).

The example flowrate loop circuitry <NUM> illustrated in <FIG> causes an adjustment of the flowrate of CcH2 through the system <NUM> based on an actual flowrate that the example flowmeter <NUM> measures and a target flowrate that the flowrate loop circuitry <NUM> determines. In some examples, the CcH2 refueler <NUM> includes an output device (e.g., a display screen, monitor, headset, etc.) to communicate information (e.g., system status, actual and target onboard pressure, actual and target onboard temperatures, etc.) to a user of the CcH2 refueler <NUM>. In some examples, the CcH2 refueler <NUM> includes an input device (e.g., a knob, a mouse, a keyboard, a touchscreen, etc.) to receive inputs from the user. In response to machine-readable instructions and/or user input(s) indicating the target flowrate, an example program or application stored in the memory <NUM> can cause the flowrate loop circuitry <NUM> to command (e.g., via electrical signals) the pump motor <NUM> to adjust the operational speed of the pump motor <NUM>. In some examples, the user input indicates a target timespan in which the refueling process is to be conducted. The example flowrate loop circuitry <NUM> can calculate the target flowrate based on the target timespan and the volume of the example onboard CcH2 tank <NUM>. For example, if the onboard CcH2 tank is <NUM><NUM>, and the target timespan is <NUM> minutes, then the flowrate loop circuitry <NUM> determines the target flowrate to be <NUM><NUM>/s.

In response to detecting the actual flowrate and determining the target flowrate, the example flowrate loop circuitry <NUM> can send a command to the pump motor <NUM> to increase or decrease the speed of the motor based on the actual and target flowrates. In some examples, the flowrate loop circuitry <NUM> calculates a flowrate error between the actual and target flowrates and continues to send the command to the pump motor <NUM> until the flowrate error satisfies a flowrate error threshold (e.g., <NUM><NUM>/s, <NUM><NUM>/s, etc.). For example, if the actual flowrate is <NUM><NUM>/s, and the target flowrate is <NUM><NUM>/s, then the flowrate loop circuitry <NUM> instructs the pump motor <NUM> to increase the operational speed of the pump motor <NUM> until the flowrate reaches <NUM><NUM>/s. Additionally or alternatively, the flowrate loop circuitry <NUM> can continue to send the instructions to the pump motor <NUM> until the flowrate error satisfies the flowrate error threshold. For example, until the actual flowrate reaches <NUM><NUM>/s or <NUM><NUM>/s, given a flowrate error threshold of <NUM><NUM>/s. In some examples, the flowrate loop circuitry <NUM> continually receives actual flowrate measurements, determines and/or receives target flowrate, calculates the flowrate error, and sends commands to the pump motor <NUM> until the flowrate error is sufficiently close to zero.

The example pressure loop circuitry <NUM> illustrated in <FIG> causes an adjustment of the pressure of CcH2 in the mixing tank <NUM> and the onboard CcH2 tank <NUM> based on an actual pressure that the first and/or second pressure sensors <NUM>, <NUM> measure(s) and the target pressure that the pressure loop circuitry <NUM> determines. In response to machine-readable instructions and/or user input(s) indicating the target pressure, the example program and/or application stored in the memory <NUM> can cause the pressure loop circuitry <NUM> to command the cryogenic pump <NUM> to adjust the output pressure of the cryogenic pump <NUM>. For example, the machine-readable instructions indicate a target onboard pressure of <NUM> bar to the pressure loop circuitry <NUM>, and the first pressure sensor <NUM> indicates an actual onboard pressure measurement of <NUM> bar to the pressure loop circuitry <NUM>.

In response to receiving the target pressure (e.g., <NUM> bar) and the actual pressure (e.g., <NUM> bar), the example pressure loop circuitry <NUM> can determine an intermediate target pressure (e.g., <NUM> bar) that is sufficiently higher than the actual pressure but not so high as to cause any catastrophic pressure increases to the system <NUM> (e.g., a pressure increase that causes a leak, rupture, deformation, etc.). In response to determining the intermediate target pressure, the example pressure loop circuitry <NUM> can command the cryogenic pump <NUM> to output a pressure of <NUM> bar to introduce positive pressure head to the system <NUM>. In some examples, the cryogenic pump <NUM> adjusts actuation of the cold end piston to compress the LH2 into a smaller displacement volume in a cylinder of the cryogenic pump <NUM> to increase the output pressure (e.g., displacement volume of <NUM> cubic centimeters (cm<NUM>) for a <NUM> bar output versus displacement volume of <NUM><NUM> for a <NUM> bar output). In some examples, the pressure loop circuitry <NUM> calculates a pressure error between the actual and intermediate target pressures and continues to send the command to the cryogenic pump <NUM> until the pressure error satisfies a pressure error threshold (e.g., <NUM> bar, <NUM> bar, <NUM> bar, etc.). For example, when the actual pressure of the mixing tank <NUM> is <NUM> bar, and the intermediate target pressure is <NUM> bar, then the pressure loop circuitry <NUM> instructs the cryogenic pump <NUM> to increase the output pressure of the CcH2 until the actual pressure of the mixing tank <NUM> is <NUM> bar. Additionally or alternatively, the pressure loop circuitry <NUM> can continue to send the instructions to the cryogenic pump <NUM> until the pressure error satisfies the pressure error threshold. For example, until the actual pressure reaches <NUM> bar or <NUM> bar, given a pressure error threshold of <NUM> bar. In some examples, the pressure loop circuitry <NUM> causes the system to end the refueling process and to shut off the example refueler valve <NUM> in response to the actual pressure of the onboard CcH2 tank <NUM> reaching the target pressure and/or increasing to a value sufficiently close to the target pressure (e.g., <NUM> bar, <NUM> bar, <NUM> bar, etc.). In some examples, the pressure loop circuitry <NUM> continually receives actual pressure measurements, determines and/or receives target pressures and/or intermediate target pressures, calculates the pressure error, and sends commands to the cryogenic pump <NUM> until the pressure error is sufficiently close to zero.

The example temperature loop circuitry <NUM> illustrated in <FIG> causes an adjustment of the temperature of CcH2 in the mixing tank <NUM> and the onboard CcH2 tank <NUM> based on an actual temperature that the first and/or second temperature sensors <NUM>, <NUM> measure(s) and a target temperature that the temperature loop circuitry <NUM> determines. In response to machine-readable instructions and/or user input(s) indicating the target temperature, the example program and/or application stored in the memory <NUM> can cause the temperature loop circuitry <NUM> to command the proportional valve <NUM> to adjust the flowrate of the CcH2 through the vaporizer <NUM>. For example, the user input(s) indicate(s) a target onboard temperature of <NUM> to the temperature loop circuitry <NUM>, and the first temperature sensor <NUM> indicates an actual onboard temperature measurement of <NUM> to the temperature loop circuitry <NUM>. In response to detecting the actual temperature of <NUM> and determining and/or receiving the target temperature of <NUM>, the example temperature loop circuitry <NUM> sends a command to the proportional valve <NUM> to increase the flowrate of the CcH2 into the vaporizer <NUM> until the actual temperature reaches <NUM>.

In some examples, the temperature loop circuitry <NUM> calculates a temperature error between the actual and target temperature and continues to send the command to the proportional valve <NUM> until the temperature error satisfies a temperature error threshold (e.g., <NUM>, <NUM>, <NUM>, etc.). In some examples, the temperature loop circuitry <NUM> continues to send the instructions to the proportional valve <NUM> until the temperature error satisfies the temperature error threshold. For example, until the actual temperature reaches <NUM> or <NUM>, given a temperature error threshold of <NUM>. In some examples, the temperature loop circuitry <NUM> continually receives actual temperature measurements, determines and/or receives target temperature(s), calculates the temperature error, and sends commands to the proportional valve <NUM> until the temperature error is sufficiently close to zero.

The example position loop circuitry <NUM> illustrated in <FIG> causes actuation of the cryogenic pump <NUM>, the pump motor <NUM>, the proportional valve <NUM>, the refueler valve <NUM>, the defueler valve <NUM>, and/or the split valve <NUM> based on command(s) from the flowrate loop circuitry <NUM>, the pressure loop circuitry <NUM>, and/or the temperature loop circuitry <NUM>. In response to the command(s), the position loop circuitry <NUM> detects an actual position (e.g., valve piston displacement) or operational state (e.g., motor speed) and determines a target position or operational state. For example, the temperature loop circuitry <NUM> instructs the proportional valve <NUM> to increase the CcH2 flow through the vaporizer <NUM>. In response, the position loop circuitry <NUM> detects the actual position (e.g., <NUM> displacement from a calibrated zero position) of a valve member (e.g., piston, spool, plug, etc.) within the proportional valve <NUM> and determine the target position (e.g., <NUM> displacement) of the valve member based on the actual position, the actual temperature, and the target temperature. The example position loop circuitry <NUM> commands the proportional valve <NUM> to actuate the valve member until the actual position reaches <NUM> displacement.

In some examples, the position loop circuitry <NUM> calculates a position error between the actual and target positions and continues to send the command to the proportional valve <NUM> to actuate the valve member until the position error satisfies a position error threshold (e.g., <NUM>, <NUM>, <NUM>, etc.). In some examples, the position loop circuitry <NUM> continues to send the instructions to the proportional valve <NUM> until the position error satisfies the position error threshold. For example, until the actual position reaches <NUM> or <NUM>, given the position error threshold of <NUM>. In some examples, the position loop circuitry <NUM> continually and/or simultaneously receives actual position(s), determines and/or receives target position(s), calculates the position error(s), and sends commands to the cryogenic pump <NUM>, the pump motor <NUM>, the proportional valve <NUM>, the refueler valve <NUM>, the defueler valve <NUM>, and/or the split valve <NUM> until the position error is sufficiently close to zero.

<FIG> illustrates a second example CcH2 refueling system <NUM> ("system <NUM>") to supply CcH2 fuel to the example aircraft <NUM> up to the target pressure of the onboard CcH2 tank <NUM> while achieving a controlled and/or consistent temperature. The example system <NUM> includes the example LH2 supply tank <NUM>, the example first proportional valve <NUM>, the example flowmeter <NUM>, the example refueler valve <NUM>, the example VJ flowlines <NUM>, and the example flexible VJ flowline(s) <NUM> as illustrated in <FIG> and <FIG>. The example system <NUM> further includes the example CcH2 refueler <NUM>, the example hydrogen aircraft <NUM>, the example onboard CcH2 tank <NUM>, the example first pressure sensor <NUM>, the example first temperature sensor <NUM>, the example transfer pump <NUM>, the example cryogenic pump <NUM>, the example pump motor <NUM>, the example mixing tank <NUM>, the example second pressure sensor <NUM>, the example second temperature sensor <NUM>, the example defueler valve <NUM>, the example split valve <NUM>, the example hydrogen containers <NUM>, the example CcH2 refueler controller <NUM>, the example processor circuitry <NUM>, the example memory <NUM>, the example flowrate loop circuitry <NUM>, the example pressure loop circuitry <NUM>, the example temperature loop circuitry <NUM>, and the example position loop circuitry <NUM> as illustrated in <FIG>. As illustrated in <FIG>, the example system <NUM> includes example hydrogen storage tanks <NUM>, an example regulator valve <NUM>, and an example third pressure sensor <NUM>. The example system <NUM> illustrated in <FIG> adjusts flow of sH2 into the mixing tank <NUM> to control the temperature of the CcH2 in the mixing tank <NUM> and the onboard CcH2 tank <NUM>. Rather than the vaporizer <NUM> of system <NUM> in <FIG>, the system <NUM> uses highly compressed (e.g., <NUM> bar or greater) sH2 in the example hydrogen storage tanks <NUM> as the sH2 source.

The example system <NUM> illustrated in <FIG> includes the hydrogen storage tanks <NUM> to supply the mixing tank <NUM> with sH2 and to provide an adjustment to the temperature of the CcH2 in the mixing tank <NUM> and in the onboard CcH2 tank <NUM>. The example hydrogen storage tanks <NUM> can be of a same or a similar design and/or structure as the example hydrogen containers <NUM>. However, the example hydrogen storage tanks <NUM> are preloaded with sH2 compressed up to a pressure (e.g., <NUM> bar, <NUM> bar, <NUM> bar, etc.) at non-cryogenic temperatures (e.g., <NUM>, <NUM>, <NUM>, etc.). In some examples, the hydrogen storage tanks <NUM> illustrated in <FIG> contain sH2 at pressures greater than the output pressures of the cryogenic pump <NUM> and/or greater than the target onboard pressures (e.g., <NUM> bar to <NUM> bar). In some examples, the hydrogen storage tanks <NUM> contain sH2 at pressures less than the output pressures of the cryogenic pump <NUM> and/or less than the target onboard pressures. In such examples, the example system <NUM> includes a pump and/or compressor downstream of the proportional valve <NUM> and upstream of the mixing tank <NUM>. Although four hydrogen storage tanks <NUM> are illustrated in <FIG>, one or more hydrogen storage tanks <NUM> may be included in the example system <NUM>.

The example system <NUM> illustrated in <FIG> includes the regulator valve <NUM> to set the pressure of the sH2 leaving the proportional valve <NUM> equal to or sufficiently close to the pressure of the mixing tank <NUM>. In some examples, the regulator valve <NUM> is pressure reducing regulator that reduces an input pressure (e.g., <NUM> bar) to a lower output pressure (e.g., <NUM> bar) despite fluctuations in the input pressure (e.g., pressure reductions from <NUM> bar to <NUM> bar). In other words, as the proportional valve <NUM> releases sH2 from the hydrogen storage tanks <NUM>, the output pressure of the proportional valve <NUM> decreases, but the regulator valve <NUM> is still able to provide a consistent output pressure to the mixing tank <NUM>.

Since the hydrogen storage tanks <NUM> do not provide sH2 to the mixing tank <NUM> at a same or similar pressure as the internal pressure of the mixing tank <NUM> (like the example vaporizer <NUM> of <FIG>), the example pressure loop circuitry <NUM> and the example position loop circuitry <NUM> control the example regulator valve <NUM>. For example, the temperature loop circuitry <NUM> determines that the actual onboard temperature is less than the target temperature and causes the proportional valve <NUM> to increase the flowrate of sH2 to the mixing tank <NUM>. In response to the command from the temperature loop circuitry <NUM>, the example pressure loop circuitry <NUM> can read the actual pressure in the mixing tank <NUM> from the second pressure sensor <NUM> and command the regulator valve <NUM> to set an output pressure to match or come sufficiently close to (e.g., within <NUM> bar, <NUM> bar, <NUM> bar, etc. of) the actual pressure of the mixing tank <NUM>.

The example system <NUM> illustrated in <FIG> includes the example third pressure sensor <NUM> to detect the output pressure of the regulator valve <NUM>. In some examples, the pressure loop circuitry <NUM> obtains the actual pressure of the mixing tank <NUM> from the second pressure sensor <NUM> and the output pressure of the regulator valve <NUM> from the third pressure sensor <NUM>. The example pressure loop circuitry <NUM> can command the regulator valve <NUM> to adjust the output pressure to match the actual pressure of the mixing tank <NUM>. Additionally or alternatively, the pressure loop circuitry <NUM> can calculate a regulator error as a difference between the actual pressure of the mixing tank <NUM> and the output pressure of the regulator valve <NUM> and can continue to instruct the regulator valve <NUM> to adjust the output pressure until the regulator error is sufficiently close to zero (e.g., <NUM> bar, <NUM> bar, <NUM> bar, etc.).

In some examples, the position loop circuitry <NUM> detects an actual position of a valve member in the regulator valve <NUM> that facilitates the output pressure. The example position loop circuitry <NUM> can also determine a target position of the valve member based on the output pressure of the regulator valve <NUM> and the actual pressure of the mixing tank <NUM>. In some examples, the position loop circuitry <NUM> causes the regulator valve <NUM> to actuate the valve member until the actual position matches the target position, until a positional error is sufficiently close to zero, or until the pressure loop circuitry <NUM> determines that the pressure error is sufficiently close to zero, as described previously.

<FIG> illustrates a third example CcH2 refueling system <NUM> ("system <NUM>") to supply CcH2 fuel to the example hydrogen aircraft <NUM> up to the target pressure of the example onboard CcH2 tank <NUM> at a controlled and/or consistent temperature. The example system <NUM> includes the example LH2 supply tank <NUM>, the example proportional valve <NUM>, the example flowmeter <NUM>, the example refueler valve <NUM>, the example VJ flowlines <NUM>, and the example flexible VJ flowline(s) <NUM> as illustrated in <FIG>. The example system <NUM> further includes the example CcH2 refueler <NUM>, the example hydrogen aircraft <NUM>, the example onboard CcH2 tank <NUM>, the example first pressure sensor <NUM>, the example first temperature sensor <NUM>, the example transfer pump <NUM>, the example mixing tank <NUM>, the example second pressure sensor <NUM>, the example second temperature sensor <NUM>, the example split valve <NUM>, the example defueler valve <NUM>, the example hydrogen containers <NUM>, the example CcH2 refueler controller <NUM>, the example processor circuitry <NUM>, the example memory <NUM>, the example flowrate loop circuitry <NUM>, the example pressure loop circuitry <NUM>, the example temperature loop circuitry <NUM>, the example position loop circuitry <NUM>, the example hydrogen storage tanks <NUM>, and the example third pressure sensor <NUM> as illustrated in <FIG> and/or <NUM>. As illustrated in <FIG>, the example system <NUM> includes an example CcH2 supply tanks <NUM>, a first regulator valve 304a, and a second regulator valve 304b. For the figures disclosed herein, the example first regulator valve 304a and the example second regulator valve 304b are of the same type and functionality as the example regulator valve <NUM> illustrated in <FIG>. The example systems <NUM> and <NUM> illustrated in <FIG> and <FIG> include the LH2 supply tank <NUM>, the transfer pump <NUM>, and the cryogenic pump <NUM> to serve as a source of CcH2. In contrast, the example system <NUM> includes the CcH2 supply tank <NUM> and the second regulator valve 304b to serve as the CcH2 source.

The example system <NUM> illustrated in <FIG> includes the example CcH2 supply tank <NUM> to provide CcH2 fuel to the system <NUM> for the refueling process. In some examples, the CcH2 supply tank <NUM> is of a same or a similar design, structure, and/or functionality as the onboard CcH2 tank <NUM>. Similar to the example LH2 supply tank <NUM> of <FIG>, the example CcH2 supply tank <NUM> can be a mobile tank capable of being transported to the example CcH2 refueler <NUM> and the example aircraft <NUM> via a truck, trailer, bus, etc. The example CcH2 supply tank <NUM> allows for reduced complication of the system <NUM> with respect to the example systems <NUM> and/or <NUM> due to the elimination of the cryogenic pump <NUM> and the pump motor <NUM>. However, the example CcH2 supply tank <NUM> may not be available at the time of the refueling process, for example when the CcH2 supply tank <NUM> is empty or when the cost to provide the CcH2 supply tank <NUM> to the CcH2 refueler <NUM> is too great for a given refueling budget.

The example system <NUM> illustrated in <FIG> includes the example second pressure regulator 304b to adjust an output pressure of the CcH2 supply tank <NUM>. In some examples, the second pressure regulator 304b adjusts the output pressure based on the actual pressure of the mixing tank <NUM> and/or the onboard CcH2 tank <NUM> and based on the target pressure and/or the intermediate target pressure, as mentioned previously. For example, the pressure loop circuitry <NUM> determines an intermediate target pressure of <NUM> bar, and the second pressure sensor <NUM> detects an actual pressure of <NUM> bar. Thus, the example pressure loop circuitry <NUM> can command the second regulator valve 304b to increase the output pressure until the actual pressure reached <NUM> bar or until a pressure error (e.g., that the pressure loop circuitry <NUM> calculates) is sufficiently close to zero (e.g., <NUM> bar, <NUM> bar, <NUM> bar, etc.), as described previously.

<FIG> illustrates an example hydrogen aircraft <NUM> to be refueled with CcH2 fuel. The example hydrogen aircraft <NUM> includes a fuselage <NUM>, a first (e.g., left) wing <NUM>, a second (e.g., right) wing <NUM>, a first horizontal stabilizer <NUM>, a second horizontal stabilizer <NUM>, a first CcH2 tank <NUM>, a second CcH2 tank <NUM>, a first engine <NUM>, and a second engine <NUM>. The example hydrogen aircraft <NUM> can be a military aircraft or a commercial aircraft that stores CcH2 onboard as a fuel source for the first engine <NUM>, the second engine <NUM>, and/or additional or alternative engine(s) not shown in <FIG>. The example systems <NUM>, <NUM>, and/or <NUM> of <FIG> can be used to refuel the first and/or second CcH2 tanks <NUM>, <NUM> of the hydrogen aircraft <NUM>. In some examples, the first CcH2 tank <NUM> and/or the second CcH2 tank <NUM> are removable and replaceable and are refueled while attached and/or detached from the hydrogen aircraft <NUM>.

The example hydrogen aircraft <NUM> illustrated in <FIG> includes the example fuselage <NUM> to hold cargo, passengers, landing gear, etc. while in flight. The example fuselage <NUM> can be designed with a truss framework, a monocoque construction, and/or a semi-monocoque construction to provide structural integrity to the aircraft during takeoff, landing, or in flight. In some examples, the fuselage <NUM> also includes a wing box to attach the first and second wings <NUM>, <NUM> to the hydrogen aircraft <NUM>.

The example hydrogen aircraft <NUM> illustrated in <FIG> includes the example first and second wings <NUM>, <NUM> to provide lift to the hydrogen aircraft <NUM>. The example first and second wings <NUM>, <NUM> illustrated in <FIG> are swept back from root to tip. In some examples, the first and second wings <NUM>, <NUM> are swept forward, straight sideways, or delta wings depending on the function, intended range, intended endurance, and/or intended velocity of the hydrogen aircraft <NUM>. In some examples, the first and second wings <NUM>, <NUM> include latching mechanisms that secure the example first and second CcH2 tanks <NUM>, <NUM> to the hydrogen aircraft <NUM>. For example, the first and second wings <NUM>, <NUM> include male or female component(s) of latching mechanism(s) (e.g., a two-stage rotary latch, a magnetic latch, a cam latch, a cam lock, etc.).

The example hydrogen aircraft <NUM> illustrated in <FIG> includes the example first and second horizontal stabilizers <NUM>, <NUM> to provide longitudinal stability and control of the hydrogen aircraft <NUM>. The example first horizontal stabilizer <NUM> is a first set of tail wings with one or more airfoil profiles in a swept back configuration. The example second horizontal stabilizer <NUM> is a second set of tail wings with the same airfoil profile(s) and swept back to the same degree. In some examples, the hydrogen aircraft <NUM> includes one horizontal stabilizer with a single set of tail wings instead of two horizontal stabilizers as shown in <FIG>. In some examples, the first and second horizontal stabilizers <NUM>, <NUM> include latching mechanisms that secure the example first and second CcH2 tanks <NUM>, <NUM> to the hydrogen aircraft <NUM>. For example, the first and second horizontal stabilizers <NUM>, <NUM> include male or female component(s) of the latching mechanism(s) previously mentioned.

The example hydrogen aircraft <NUM> illustrated in <FIG> includes the example first and second CcH2 tanks <NUM>, <NUM> to store the CcH2 fuel onboard the hydrogen aircraft <NUM>. In some examples, the first and/or second CcH2 tanks <NUM>, <NUM> are drop tanks capable of being secured to and removed from the first and second wings <NUM>, <NUM> and the first and second horizontal stabilizers <NUM>, <NUM> via male and/or female components of the latching mechanism(s). In some examples, the first and/or second CcH2 tanks <NUM>, <NUM> are removed when the CcH2 fuel capacity is at a low enough capacity (e.g., <NUM>%, <NUM>%, <NUM>% capacity, etc.) and replaced with replenished CcH2 tanks of the same type and/or design as the first and second CcH2 tanks <NUM>, <NUM>. In some examples, the first and second CcH2 tanks <NUM>, <NUM> are not removable except via disassembly that may compromise the structural integrity, aerodynamic capability, controllability, weight distribution, performance, lifespan, etc., of the hydrogen aircraft <NUM>.

The example hydrogen aircraft <NUM> illustrated in <FIG> includes the example first and second engines <NUM>, <NUM> to provide thrust to the hydrogen aircraft <NUM>. The example first and second engines <NUM>, <NUM> illustrated in <FIG> are included in the structural framework of the example first and second onboard CcH2 tanks <NUM>, <NUM>. In some examples, the example first and second engines <NUM>, <NUM> are separate from the first and second onboard CcH2 tanks <NUM>, <NUM>, mounted on the first and second wings <NUM>, <NUM>, and are not removable from the hydrogen aircraft <NUM> except via disassembly. The example first and second engines <NUM>, <NUM> illustrated in <FIG> are propeller engines with fixed pitch, constant speed, or ground adjustable propellers. In some examples the first and second engines <NUM>, <NUM> are turboprop, turbofan, or turbojet engines attached to the first and second onboard CcH2 tanks <NUM>, <NUM> or the first and second wings <NUM>, <NUM>.

<FIG> is a chart <NUM> illustrating thermodynamic properties of LH2. The example chart <NUM> includes a first thermodynamic relationship <NUM> of LH2 to represent density (kg/m<NUM>) as a function of temperature (K) and a second thermodynamic relationship <NUM> of LH2 to represent saturated pressure (pounds per square inch (psi)) as a function of temperature (K). The thermodynamic relationships <NUM>, <NUM> of LH2 shown in <FIG> can be used to determine the mass of LH2 refueled to the onboard LH2 tank <NUM> and a target temperature and saturated pressure of the onboard LH2 tank <NUM> of <FIG>. The example <FIG> is included herein to exemplify the temperature and saturated pressure ranges of LH2 in contrast to those of CcH2, described below.

<FIG> is a chart <NUM> illustrating thermodynamic properties of CcH2. The example chart <NUM> includes a first thermodynamic relationship <NUM> of CcH2 to represent density (kg/m<NUM>) as a function of pressure (bar) at a temperature of <NUM> and a second thermodynamic relationship <NUM> of CcH2 to represent density (kg/m<NUM>) as a function of pressure (bar) at a temperature of <NUM>. The example chart <NUM> also includes a reference line <NUM> to demonstrate the effect of temperature has on the density of CcH2. For example, CcH2 at a temperature of <NUM> and a pressure of <NUM> bar has a density of <NUM>/m<NUM>, and CcH2 at <NUM> and a pressure of <NUM> bar also has a density of <NUM>/m<NUM>. When the CcH2 fuel is refueled to the aircraft <NUM> at <NUM>, the onboard CcH2 tank <NUM> has an internal volume of <NUM><NUM>, and the aircraft <NUM> relies on <NUM> of CcH2 fuel for an intended flight, then the example onboard CcH2 tank <NUM> can be designed with an internal pressure limit of <NUM> bar. When the CcH2 fuel is refueled to the aircraft <NUM> at <NUM> with the same onboard CcH2 tank <NUM> and the same amount of CcH2 fuel, then the example CcH2 tank <NUM> can be designed with an internal pressure limit of <NUM> bar. In the latter case, the example onboard CcH2 tank <NUM> includes more material (e.g., aluminum, steel, carbon fiber, etc.) to structurally facilitate containment of the potentially higher pressures. By utilizing an onboard CcH2 tank <NUM> with a pressure limit of <NUM> bar instead of <NUM> bar, the example aircraft <NUM> saves a significant amount of weight that may be allocated to other resources (e.g., carrying more cargo, passengers, better performance, longer range, etc.). Thus, the example CcH2 refueling systems <NUM>, <NUM>, and/or <NUM> of <FIG> are utilized to allow the example hydrogen aircraft <NUM> of <FIG>, the example hydrogen aircraft <NUM> of <FIG>, and/or another hydrogen vehicle (e.g., car, truck, bus, ship, etc.) to refuel the CcH2 at a precise temperature based on the pressure limits (e.g., <NUM> bar) of an onboard CcH2 tank (e.g., onboard CcH2 tank <NUM>, the first CcH2 tank <NUM>, the second CcH2 tank <NUM>, etc.).

<FIG> is a flow diagram illustrating an example process/operation <NUM> of the CcH2 refueler controller <NUM> to control operation of the CcH2 refueling systems <NUM>, <NUM>, <NUM> as disclosed herein. While the example process/operation <NUM> is described with primary reference to refueling the example onboard CcH2 tank <NUM> of the example aircraft <NUM>, the process/operation <NUM> can be used to refuel another CcH2 tank (e.g., the first and/or second CcH2 tanks <NUM>, <NUM>) that may be onboard another hydrogen-powered vehicle, or a standalone CcH2 tank not to be onboard a hydrogen-powered vehicle.

At block <NUM>, the CcH2 refueler controller <NUM> determines whether an onboard pressure in the onboard CcH2 tank <NUM> satisfies a preliminary pressure threshold. For example, the pressure loop circuitry <NUM> requests an onboard pressure measurement from a first pressure sensor <NUM>. When the pressure loop circuitry <NUM> determines that the onboard pressure does satisfy the preliminary pressure threshold (e.g., if the onboard pressure is below <NUM> bar), then the process/operation <NUM> proceeds to block <NUM>.

When the pressure loop circuitry <NUM> determines that the onboard pressure does not satisfy the preliminary pressure threshold, then the process/operation <NUM> proceeds to block <NUM>, where the CcH2 refueler controller <NUM> opens a defueler valve <NUM>. For example, the position loop circuitry <NUM> sends a signal to an electronically-actuated valve mechanism of the defueler valve <NUM> that causes flow of the CcH2 in the onboard CcH2 tank <NUM> to flow to the split valve <NUM>.

At block <NUM>, the CcH2 refueler controller <NUM> determines whether a pressure of the mixing tank <NUM> is less than the onboard pressure of the onboard CcH2 tank <NUM>. For example, the pressure loop circuitry <NUM> continually monitors the onboard pressure via the first pressure sensor <NUM> and the pressure of the mixing tank <NUM> via the second pressure sensor <NUM> and calculates a difference between the two. The pressure loop circuitry <NUM> can determine that the condition of block <NUM> is satisfied when the onboard pressure minus the pressure of the mixing tank <NUM> is a negative value. When the pressure loop circuitry <NUM> determines that the pressure of the mixing tank <NUM> is not less than the onboard pressure of the onboard CcH2 tank <NUM>, then the process/operation <NUM> proceeds to block <NUM>.

When the pressure loop circuitry <NUM> determines that the pressure of the mixing tank <NUM> is less than the onboard pressure, then the process/operation <NUM> proceeds to block <NUM>, where the CcH2 refueler controller <NUM> causes the split valve <NUM> to direct the CcH2 flow from the onboard CcH2 tank <NUM> to the mixing tank <NUM>. For example, the position loop circuitry <NUM> detects an actual position of a valve mechanism of the split valve <NUM> and instructs the valve mechanism to actuate to target position that achieves directional flow to the mixing tank <NUM>.

At block <NUM>, when the pressure loop circuitry <NUM> determines that the pressure of the mixing tank <NUM> is not less than the onboard pressure, then the CcH2 refueler controller <NUM> causes the split valve <NUM> to direct the CcH2 flow from the onboard CcH2 tank <NUM> to the hydrogen containers <NUM> or a secondary destination, such as atmosphere. For example, the position loop circuitry <NUM> detects the actual position of the valve mechanism of the split valve <NUM> and instructs the valve mechanism to actuate to target position that achieves directional flow to the hydrogen containers <NUM>.

At block <NUM>, the CcH2 refueler controller <NUM> determines whether the onboard pressure satisfies the preliminary pressure threshold. For example, the pressure loop circuitry <NUM> reads the onboard pressure measurement from the first pressure sensor <NUM> and determines if the onboard pressure is less than the predetermined preliminary pressure threshold. When the pressure loop circuitry <NUM> determines that the onboard pressure does not satisfy the preliminary pressure threshold, then the process/operation <NUM> returns to block <NUM>.

When the pressure loop circuitry <NUM> determines that the onboard pressure does satisfy the preliminary pressure threshold, then the process/operation <NUM> proceeds to block <NUM>, where the CcH2 refueler controller <NUM> causes the refueler valve <NUM> to open. For example, the position loop circuitry <NUM> sends instruction(s) to a valve mechanism of the refueler valve <NUM> to fully open and permit flow of the CcH2 fuel to the onboard CcH2 tank <NUM>.

At block <NUM>, the example CcH2 refueler <NUM> facilitates refueling of the onboard CcH2 tank <NUM> as described in further detail in reference to an example process/operation <NUM> of <FIG>.

Once the example process/operation <NUM> to refuel the onboard CcH2 tank <NUM> ends, process/operation <NUM> proceeds to block <NUM>, where the CcH2 refueler controller <NUM> causes the refueler valve <NUM> to close. For example, the position loop circuitry <NUM> instructs the valve mechanism of the refueler valve <NUM> to fully shut off the flow, at which point the process/operation <NUM> ends.

<FIG> is a flow diagram illustrating the example process/operation <NUM> of the CcH2 refueler controller <NUM> to refuel the onboard CcH2 tank <NUM> via the CcH2 refueler <NUM>. While the example process/operation <NUM> is described with primary reference to refueling the example onboard CcH2 tank <NUM> of the example aircraft <NUM>, the process/operation <NUM> can be used to refuel another CcH2 tank (e.g., the first and/or second CcH2 tanks <NUM>, <NUM>) that may be onboard another hydrogen-powered vehicle, or a standalone CcH2 tank not to be onboard a hydrogen-powered vehicle.

The example process/operation <NUM> begins at block <NUM>, where the CcH2 refueler controller determines an intermediate target pressure of the mixing tank <NUM> based on the onboard pressure. For example, the pressure loop circuitry <NUM> determines, based on written instructions, a set of rules, and/or user input(s), that the intermediate target pressure is to be slightly higher (e.g., <NUM> bar, <NUM> bar, <NUM> bar etc.) than the actual onboard pressure to facilitate a positive pressure head in the systems <NUM>, <NUM>, and/or <NUM>.

At block <NUM>, the CcH2 refueler controller <NUM> causes pressurization of the mixing tank <NUM> based on the intermediate target pressure. For example, the position loop circuitry <NUM> sends instruction(s) to the cryogenic pump <NUM> to adjust an output pressure to sufficiently match (e.g., within <NUM> bar, <NUM> bar, <NUM> bar, etc.) the intermediate target pressure.

At block <NUM>, the CcH2 refueler controller <NUM> determines whether an actual flowrate of the CcH2 satisfies a target flowrate. For example, the flowrate loop circuitry <NUM> calculates a flowrate error between the actual flowrate and the target flowrate, where the actual flowrate is based on a measurement of the flowmeter <NUM>, and the target flowrate is based on the written instruction(s), set of rules, and/or user input(s). When the flowrate loop circuitry <NUM> determines that the actual flowrate does satisfy the target flowrate (e.g., if the flowrate error is sufficiently near zero (e.g., <NUM><NUM>/s, <NUM><NUM>/s, <NUM><NUM>/s, etc.)), then the process/operation <NUM> proceeds to block <NUM>.

When the flowrate loop circuitry <NUM> determines that the actual flowrate does not satisfy the target flowrate, then the process/operation <NUM> proceeds to block <NUM>, where the CcH2 refueler controller <NUM> adjusts the flowrate upstream of the mixing tank <NUM>. For example, the position loop circuitry <NUM> instructs the pump motor <NUM> to increase an operation speed or the second regulator valve 304b to increase an output pressure based on the current operational speed and/or current output pressure, the actual flowrate, and/or the target flowrate.

At block <NUM>, the CcH2 refueler controller <NUM> determines whether the pressure of the mixing tank <NUM> satisfies the intermediate target pressure. For example, the pressure loop circuitry <NUM> calculates a pressure error between the mixing tank <NUM> pressure and the intermediate target pressure and determine if the pressure error is sufficiently close to zero (e.g., <NUM> bar, <NUM> bar, <NUM> bar, etc.). When the pressure loop circuitry <NUM> determines that the pressure of the mixing tank <NUM> does satisfy the intermediate target pressure, then process/operation <NUM> proceeds to block <NUM>.

When the pressure loop circuitry <NUM> determines that the pressure of the mixing tank <NUM> does not satisfy the intermediate target pressure, then process/operation <NUM> proceeds to block <NUM>, where the CcH2 refueler controller <NUM> adjusts the pressure upstream of the mixing tank <NUM>. For example, the position loop circuitry <NUM> instructs the cryogenic pump <NUM> or the second regulator valve 304b to increase an output pressure based on the actual output pressure, the actual pressure of the mixing tank <NUM>, and/or the intermediate target pressure.

At block <NUM>, the CcH2 refueler controller <NUM> determines whether the onboard temperature satisfies a target temperature of the onboard CcH2 tank <NUM>. For example, the temperature loop circuitry <NUM> calculates a temperature error between the actual onboard temperature and the target temperature, where the actual temperature is based on a measurement of the first temperature sensor <NUM>, and the target temperature is based on written instruction(s), set of rules, and/or user input(s). When the temperature loop circuitry <NUM> determines that the actual temperature does satisfy the target temperature (e.g., if the temperature error is sufficiently near zero (e.g., <NUM>, <NUM>, <NUM>, etc.)), then the process/operation <NUM> proceeds to block <NUM>.

When the temperature loop circuitry <NUM> determines that the actual temperature does not satisfy the target temperature, then the process/operation <NUM> proceeds to block <NUM>, where the CcH2 refueler controller <NUM> adjusts the flowrate of sH2 into the mixing tank <NUM>. For example, when the temperature loop circuitry <NUM> determines that the actual temperature is below the target temperature, then the position loop circuitry <NUM> sends a command to the proportional valve <NUM> of <FIG> to open a valve mechanism of the proportional valve <NUM> such that the flow of sH2 into the mixing tank <NUM> sufficiently increases. Alternatively, when the temperature loop circuitry <NUM> determines that the actual temperature is above the target temperature, then the position loop circuitry <NUM> sends a command to the proportional valve <NUM> of <FIG> to close the valve mechanism of the proportional valve <NUM> such that the flow of sH2 into the mixing tank sufficiently decreases. Additionally, the position loop circuitry <NUM> instructs the regulator valve <NUM> of <FIG> or the first regulator valve 304a of <FIG> to set an output pressure upstream of the mixing tank <NUM> to match the actual pressure of the mixing tank <NUM>.

At block <NUM>, the CcH2 refueler controller <NUM> determines whether the onboard pressure satisfies a target pressure. For example the pressure loop circuitry <NUM> calculates a pressure error between the actual onboard pressure and the target pressure, where the actual pressure is based on a measurement of the first pressure sensor <NUM>, and the target pressure is based on written instruction(s), set of rules, and/or user input(s). When the pressure loop circuitry <NUM> determines that the actual onboard pressure does not satisfy the target pressure (e.g., if the pressure error is sufficiently near zero (e.g., <NUM> bar, <NUM> bar, <NUM> bar, etc.)), then the process/operation <NUM> returns to block <NUM>. When the pressure loop circuitry <NUM> determines that the actual onboard pressure does satisfy the target pressure, then the process/operation <NUM> returns to block <NUM> of <FIG>.

<FIG> is a block diagram of an example processor platform <NUM> structured to execute and/or instantiate the machine readable instructions and/or operations of <FIG> and/or <NUM> to implement the CcH2 refueler controller <NUM> of <FIG>. The processor platform <NUM> can be, for example, a server, a personal computer, a workstation, a self-learning machine (e.g., a neural network), a mobile device (e.g., a cell phone, a smart phone, a tablet such as an iPad™), or any other type of computing device.

The processor platform <NUM> of the illustrated example includes processor circuitry <NUM>. The processor circuitry <NUM> of the illustrated example is hardware. For example, the processor circuitry <NUM> can be implemented by one or more integrated circuits, logic circuits, FPGAs microprocessors, CPUs, GPUs, DSPs, and/or microcontrollers from any desired family or manufacturer. The processor circuitry <NUM> may be implemented by one or more semiconductor based (e.g., silicon based) devices. In this example, the processor circuitry <NUM> implements the example flowrate loop circuitry <NUM>, the example pressure loop circuitry <NUM>, the example temperature loop circuitry <NUM>, and the example position loop circuitry <NUM>.

The processor circuitry <NUM> of the illustrated example includes a local memory <NUM> (e.g., a cache, registers, etc.). The processor circuitry <NUM> of the illustrated example is in communication with a main memory including a volatile memory <NUM> and a non-volatile memory <NUM> by a bus <NUM>. The volatile memory <NUM> may be implemented by Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS® Dynamic Random Access Memory (RDRAM®), and/or any other type of RAM device. Access to the main memory <NUM>, <NUM> of the illustrated example is controlled by a memory controller <NUM>.

The processor platform <NUM> of the illustrated example also includes interface circuitry <NUM>. The interface circuitry <NUM> may be implemented by hardware in accordance with any type of interface standard, such as an Ethernet interface, a universal serial bus (USB) interface, a Bluetooth® interface, a near field communication (NFC) interface, a PCI interface, and/or a PCIe interface.

In the illustrated example, one or more input devices <NUM> are connected to the interface circuitry <NUM>. The input device(s) <NUM> permit(s) a user to enter data and/or commands into the processor circuitry <NUM>. The input device(s) <NUM> can be implemented by, for example, a keyboard, a button, a mouse, a touchscreen, a track-pad, a trackball, an isopoint device, and/or a voice recognition system.

One or more output devices <NUM> are also connected to the interface circuitry <NUM> of the illustrated example. The output devices <NUM> can be implemented, for example, by display devices (e.g., a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display (LCD), a cathode ray tube (CRT) display, an in-place switching (IPS) display, a touchscreen, etc.), and/or a tactile output device. The interface circuitry <NUM> of the illustrated example, thus, typically includes a graphics driver card, a graphics driver chip, and/or graphics processor circuitry such as a GPU.

The interface circuitry <NUM> of the illustrated example also includes a communication device such as a transmitter, a receiver, a transceiver, a modem, a residential gateway, a wireless access point, and/or a network interface to facilitate exchange of data with external machines (e.g., computing devices of any kind) by a network <NUM>. The communication can be by, for example, an Ethernet connection, a digital subscriber line (DSL) connection, a telephone line connection, a coaxial cable system, a satellite system, a line-of-site wireless system, a cellular telephone system, an optical connection, etc..

The processor platform <NUM> of the illustrated example also includes one or more mass storage devices <NUM> to store software and/or data. Examples of such mass storage devices <NUM> include magnetic storage devices, optical storage devices, floppy disk drives, HDDs, CDs, Blu-ray disk drives, redundant array of independent disks (RAID) systems, solid state storage devices such as flash memory devices, and DVD drives.

The machine executable instructions <NUM>, which may be implemented by the machine readable instructions of <FIG> and/or <NUM>, may be stored in the mass storage device <NUM>, in the volatile memory <NUM>, in the non-volatile memory <NUM>, and/or on a removable non-transitory computer readable storage medium such as a CD or DVD.

Systems for refueling cryo-compressed hydrogen (CcH2) tanks and methods for operating the same are disclosed herein. The examples disclosed herein refuel CcH2 tanks up to a target pressure while also controlling the temperature of the onboard CcH2 during the refueling process. The examples disclosed herein refuel the example onboard CcH2 tanks at specific temperatures (e.g., <NUM>) so that the example onboard pressures satisfy a pressure limit of the onboard CcH2 tanks. The pressure limit (e.g., <NUM> bar) of the onboard CcH2 tanks may be chosen so that the onboard CcH2 tanks can be designed with fewer structural components and reduced weight (e.g., relative to CcH2 tanks designed with pressure limits of <NUM> bar).

Claim 1:
An apparatus (<NUM>) to refuel a vessel (<NUM>) with cryo-compressed hydrogen, the apparatus (<NUM>) comprising:
a mixing tank (<NUM>);
a cryogenic pump (<NUM>) connected to a liquid hydrogen supply tank (<NUM>);
a defueler valve (<NUM>), a refuler valve (<NUM>), and a proportional valve (<NUM>) connected to hydrogen storage tanks (<NUM>), the proportional valve (<NUM>) downstream of the hydrogen storage tanks (<NUM>);
a vaporizer (<NUM>) connected to the cryogenic pump (<NUM>) via the proportional valve (<NUM>);
a refueler controller (<NUM>) configured to:
control the defueler valve (<NUM>) to defuel the vessel (<NUM>) prior to a refuel process based on a pressure of the vessel (<NUM>);
fill the mixing tank (<NUM>) with at least the cryo-compressed hydrogen based on the pressure of the vessel (<NUM>) and a pressure of the mixing tank (<NUM>), wherein the mixing tank (<NUM>) is connected upstream of the vessel (<NUM>) and is structured to include the cryo-compressed hydrogen;
control the refueler valve (<NUM>) to initiate the refuel process of the vessel (<NUM>);
control the proportional valve (<NUM>) to adjust a temperature of the mixing tank (<NUM>) in response to a temperature of the vessel (<NUM>) not satisfying a target temperature of the vessel (<NUM>) during the refuel process, wherein the temperature of the mixing tank (<NUM>) is to be adjusted based on an increase or a decrease of flow of supercritical hydrogen; and
end the refuel process in response to the pressure of the vessel (<NUM>) satisfying a target pressure of the vessel (<NUM>).