Hydrogen fuel replenishment system and method

Abstract

A system and method for replenishing a liquefied fuel (e.g., hydrogen) is provided. The system includes a cryogenic tank for storing a liquefied fuel, a pump insertable into the cryogenic tank, and a switching valve. The pump has a piston, an inlet, and an isolation valve configured to supply the liquefied fuel to the inlet. The switching valve is controlled to flow vapor from the pump and the liquefied fuel contacting a backside of the piston to the inlet of the pump. At least one block valve is also connected with the cryogenic tank and the pump. At least one of the switching valve, the at least one block valve, and the isolation valve is controllable to operate the system in one of three operating modes including a pressure increase mode, a pressure hold mode, and a pressure decrease mode.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application No. 17 / 677,394, filed February 22, 2022, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates primarily to methods and systems for pumping or distributing liquefied fuels. More specifically, the disclosed subject matter relates to systems, pumps, and methods for pumping and / or replenishing hydrogen. Background Technology

[0004] Many motor vehicles are currently powered by internal combustion engines that use fossil fuels. Due to the limited supply and adverse environmental impacts associated with burning petroleum-derived fuels, vehicles powered by alternative, environmentally friendly fuels (e.g., hydrogen) are now being developed. Fuel cells can be used to generate electricity for motor vehicles by electrochemically reacting hydrogen fuel with an oxidant (e.g., air). Supplying or refueling fuel for fuel cell vehicles (FCVs) and other hydrogen-powered vehicles presents different challenges compared to adding petroleum-based fuels (e.g., gasoline) to vehicles.

[0005] Hydrogen refueling stations for fuel cell vehicles can store the fuel as a liquid before it is dispensed as compressed gaseous hydrogen to the vehicle. The liquefied gas or fuel (e.g., liquid hydrogen) can be stored in a cryogenic tank insulated from the environment. However, when the liquid absorbs heat leaking from the environment, the heat leaking into the tank causes the liquefied fuel to evaporate, producing “vaporized” vapor. As the vapor continues to accumulate inside the tank, the pressure inside increases. Excess vapor must be released into the environment through a safety valve to keep the tank below its pressure limits, resulting in the loss of some liquefied fuel or gas. A system is needed to minimize vaporization and / or manage the headspace pressure in the storage tank. Summary of the Invention

[0006] This disclosure provides a system and method for storing and distributing liquefied fuels. For example, the liquefied fuel may include or be hydrogen, and the system is for storing and distributing liquid hydrogen. In some embodiments, the system is used to refuel a fuel cell-based vehicle with hydrogen.

[0007] According to some embodiments, such a system includes: a cryogenic tank configured to store liquefied fuel therein, and a pump configured to be disposed within the cryogenic tank (i.e., with its inlet immersed in the liquefied fuel within the cryogenic tank) and to supply a flow of liquefied fuel from the cryogenic tank. The pump includes a piston, an inlet, and an isolation valve configured to supply the liquefied fuel to the inlet.

[0008] The system further includes: a first conduit fluidly connected to a vapor pump chamber configured to hold vapor of liquefied fuel in the pump, and a second conduit fluidly connected to a first liquid pump chamber configured to hold the liquefied fuel in contact with the back side of the piston. When the pump operates in extended or retracted mode, this liquefied fuel from the back side of the piston can absorb dynamic heat and can be hotter than the liquefied fuel from the inlet of the cryogenic tank. In some embodiments, the vapor pump chamber is an upper pump chamber in the upper part of the pump, and one or more of the liquid pump chambers are lower pump chambers in the lower part of the pump.

[0009] According to some embodiments, the system includes a switching valve fluidly connected to the first conduit and the second conduit, and the switching valve is configured to allow vapors of liquefied fuel in the pump and liquefied fuel in contact with the back side of the piston to flow through a third conduit to the inlet of the pump.

[0010] The system also includes at least one isolation valve fluidly connected to the first conduit, the second conduit, and the top space of the cryogenic tank. This at least one isolation valve is fluidly connected to the switching valve. Each of the switching valve and the at least one isolation valve can be opened or closed.

[0011] The system is configured to operate in one of three modes, including a "pressure increase" mode, a "pressure hold" mode, and a "pressure decrease" mode, to increase, hold, or decrease the pressure in the top space of the cryogenic tank, respectively.

[0012] The system may also include a controller connected to the cryogenic tank, at least one isolation valve, and a switching valve. The controller is configured to measure the headspace pressure within the cryogenic tank and control the at least one isolation valve, the switching valve, and / or the isolation valve, such that the system operates in one of the three operating modes based on the headspace pressure.

[0013] In some embodiments, in a pressure-increasing mode, the switching valve is closed and the at least one isolation valve is open. The isolation valve may be closed or open. In a pressure-holding mode, the switching valve is open, the at least one isolation valve is closed, and the isolation valve is open. In a pressure-decreasing mode, the switching valve is open, the at least one isolation valve is open, and the isolation valve is closed.

[0014] In some embodiments, the liquefied fuel is liquid hydrogen, and the system is a hydrogen refueling system. This system is used to refuel fuel, as a compressed gas, into a fuel cell vehicle.

[0015] The system also includes an exhaust line fluidly connected to the pump and configured to distribute a stream of liquefied fuel out of the pump. In some embodiments, this stream of liquefied fuel may be provided to a distributor and distributed to an onboard tank in a fuel cell vehicle.

[0016] In some embodiments, the switching valve is disposed outside the pump. The pump has a double-walled pump housing. The first pipe, the second pipe, and the third pipe are disposed between the two walls of the pump housing.

[0017] In some embodiments, the pumps include more than one (e.g., two or more) submerged liquid pumps disposed within the cryogenic tank. Each pump has its own inlet, or the two or more submerged liquid pumps share a single inlet. The two or more submerged liquid pumps may be connected in parallel to the first conduit, the second conduit, and the third conduit, respectively.

[0018] In one aspect, the present invention provides a hydrogen fuel refueling system. The system includes a cryogenic tank configured to store a liquefied fuel, wherein the liquefied fuel is hydrogen, and a pump configured to be disposed within the cryogenic tank. The pump is configured to provide a flow of liquefied fuel from the cryogenic tank. The pump has a piston, an inlet, and an isolation valve configured to supply the liquefied fuel to the inlet. The piston has a front side facing the inlet and a back side opposite the front side.

[0019] The system also includes a first conduit fluidly connected to a vapor pump chamber configured to hold vapor of liquefied fuel in the pump, and a second conduit fluidly connected to a first liquid pump chamber configured to hold the liquefied fuel in contact with the back side of the piston.

[0020] The system also includes a switching valve fluidly connected to the first and second conduits. This switching valve is configured to allow vapors of liquefied fuel in the pump and liquefied fuel in contact with the back side of the piston to flow through a third conduit to the pump inlet. The system also includes at least one isolation valve fluidly connected to the first conduit, the second conduit, the cryogenic tank, and the switching valve.

[0021] The system may also include a controller connected to the cryogenic tank, the at least one isolation valve, and the switching valve. The controller is configured to actuate the at least one isolation valve, the switching valve, and / or the isolation valve to operate the system in one of three operating modes based on the headspace pressure in the cryogenic tank. The three operating modes include a pressure increase mode, a pressure hold mode, and a pressure decrease mode.

[0022] The controller may include one or more processors and at least one tangible, non-transitory machine-readable medium encoded with one or more programs, which will be executed by the one or more processors to control components of the system. For example, the controller may be configured to measure the headspace pressure and actuate the at least one isolation valve, switching valve, and / or shut-off valve.

[0023] In another aspect, this disclosure provides a method for using a system as described herein. This method includes the steps of: providing liquefied fuel stored inside a cryogenic tank; measuring the headspace pressure inside the cryogenic tank; and determining, based on the headspace pressure, an operating mode for operating the system. The operating mode is one of three operating modes: a pressure increase mode, a pressure hold mode, and a pressure decrease mode. The method further includes actuating at least one of the at least one isolation valve, switching valve, and shut-off valve to operate the system in the operating mode.

[0024] In some embodiments, when the headspace pressure is below a first threshold pressure (P1), the pressure increase mode is determined and activated. When the headspace pressure is within the range from the first threshold pressure (P1) to a second threshold pressure (P2), where P2 > P1, the pressure hold mode is determined and activated. When the headspace pressure is above the second threshold pressure (P2), the pressure decrease mode is determined and activated.

[0025] In some embodiments, in the pressure increase mode, the switching valve is closed and the at least one isolation valve is open. The isolation valve may be closed or open. In the pressure hold mode, the switching valve is open, the at least one isolation valve is closed, and the isolation valve is open. In the pressure decrease mode, the switching valve is open, the at least one isolation valve is open, and the isolation valve is closed.

[0026] The method may further include pumping a liquefied fuel stream from the cryogenic tank and away from the pump to an exhaust line. In some embodiments, the liquefied fuel comprises hydrogen, and the method is used to refuel a fuel cell vehicle with hydrogen. The liquefied fuel stream is pumped to a distributor and distributed to an onboard tank of the fuel cell vehicle.

[0027] The systems and methods provided in this disclosure offer numerous advantages as described herein. For example, in some embodiments, this disclosure provides a system for hydrogen storage and refueling. Benefits include the ability to operate in multiple modes based on headspace pressure, manage headspace pressure, and minimize liquefied fuel loss. This system minimizes or eliminates the loss of liquefied fuels such as hydrogen, or has minimized hydrogen vaporization losses. Attached Figure Description

[0028] This disclosure can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, by convention, the various features in the drawings are not necessarily drawn to scale. Rather, for clarity, the dimensions of the various features have been arbitrarily enlarged or reduced. Throughout the specification and drawings, the same reference numerals denote the same features.

[0029] Figure 1 It is based on some implementation schemes, including a cross-sectional schematic block diagram of a typical system of an immersion cryogenic pump.

[0030] Figure 2 yes Figure 1 An enlarged view of a portion of an exemplary system, with additional reference numerals.

[0031] Figure 3 Illustrations are shown according to some embodiments Figure 1 An exemplary system includes a flow path for liquefied fuel fluids (e.g., liquids and vapors) when the cryogenic pump is in a retracted mode with the piston retracted.

[0032] Figure 4 Illustrations are shown according to some embodiments Figure 1 An exemplary system includes a flow path for liquefied fuel fluids (e.g., liquids and vapors) when the cryogenic pump is in an extended mode with the piston extended.

[0033] Figure 5 Illustrations are shown according to some embodiments Figure 1 An exemplary system includes a flow path for liquefied fuel fluids (e.g., liquids and vapors) when the cryogenic pump is in retraction mode and the system is in pressure reduction mode.

[0034] Figure 6 Illustrations are shown according to some embodiments Figure 1 An exemplary system includes a flow path for a liquefied fuel fluid (e.g., liquid and vapor) when the cryogenic pump is in an extended mode and the system is in a pressure reduction mode, wherein the piston extends in the pressure reduction mode.

[0035] Figure 7 This is a flowchart illustrating an exemplary method according to some embodiments. Detailed Implementation

[0036] The description of exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are considered an integral part of the entire written description. In this specification, relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “upward,” “downward,” “top,” and “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to orientations as described subsequently or as shown in the drawings discussed. These relative terms are for ease of description and do not require the device to be constructed or operated in a particular orientation. Terms relating to attachment, coupling, etc. (e.g., “connection” and “interconnection”) refer to a relationship in which structures are directly or indirectly fixed or attached to each other through intermediate structures, and to active or rigid connections or relationships, unless otherwise explicitly described.

[0037] For the purposes described below, it should be understood that alternative variations and embodiments may be taken from the examples described below. It should also be understood that the specific articles, compositions and / or methods described herein are exemplary and should not be considered limiting.

[0038] In this disclosure, the singular forms “a,” “an,” and “the” include plural references, and references to a particular numerical value include at least that particular value unless the context explicitly indicates otherwise. When a value is expressed as an approximation using the antecedent “about,” it should be understood that the particular value forms another embodiment. As used herein, “about X” (where X is a numerical value) preferably refers to ±10% of the referenced value, including the end value. For example, the phrase “about 8” preferably refers to a value of 7.2 to 8.8, including the end value. Where present, all ranges are inclusive and composable. For example, when listing a range of “1 to 5,” the listed range should be interpreted as including the ranges “1 to 4,” “1 to 3,” “1-2 and 4-5,” “1-3 and 5,” “2-5,” etc. Furthermore, when an affirmative list of alternatives is provided, such a list can be interpreted as meaning that any alternative can be excluded, for example, by a negative limitation in the claims. For example, when listing the range “1 to 5”, the listed range can be interpreted to include cases where any of 1, 2, 3, 4, or 5 is negatively excluded; thus, the statement “1 to 5” can be interpreted as “1 and 3-5, but not 2”, or simply “excluding 2”. Any component, element, property, or step expressly referenced herein can be expressly excluded from the claims, whether such component, element, property, or step is listed as an alternative or whether it is referenced separately.

[0039] Unless otherwise explicitly stated, the terms “substantially” and “substantially the same” as used herein shall be understood to cover parameters having fluctuations within a suitable range, such as ±10% or ±15% fluctuations in the parameter. In some embodiments, the fluctuation range is within ±10%.

[0040] Unless otherwise explicitly stated, liquefied fuels such as hydrogen are stored in storage tanks and pumped out in liquid form using a pump. It can be dispensed as a gaseous or liquid fuel into the vehicle's receiving tank. In this disclosure, the terms "refueling" and "fuel replenishment" are used interchangeably.

[0041] As used herein, when an element or component is described as forming a connection to, coupled to, or in contact with another element or component, it may be directly connected to, directly coupled to, or directly in contact with a particular element or component, or an intermediate element or component may be connected to, coupled to, or in contact with the particular element or component. When an element or component is described as being "directly connected to," "directly coupled to," or "directly in contact with" another element, there is no intermediate element or component.

[0042] As used herein, the term "thermally coupled to" will be understood as components being coupled together directly or through an intermediate component, such that heat can be transferred between the components, and the components may be in indirect contact with each other or through an intermediate component. As used herein, the terms "fluidly coupled (or connected) to" or "fluidly coupled (or connected)" will be understood as a component being connected to a pipe or conduit and configured to allow gas or liquid to flow through the component. As used herein, the term "electrically connected" will be understood to encompass electrical connections using wired or wireless connections.

[0043] As used herein, the term "extension" will be understood to include a cryogenic pump operating mode in which the piston rod extends and compression is provided within the cryogenic pump. The term "retraction" will be understood to include different operating modes of the cryogenic pump in which the piston rod moves during an intake stroke in the opposite direction of extension. In some embodiments, the piston has a front surface facing the inlet. In the extension mode, the piston moves toward the inlet. In the retraction mode, the piston moves further away from the inlet.

[0044] The check valve described herein is a one-way valve that automatically opens or closes in only one direction. The isolation valve described herein can be controlled to open or close. When the isolation valve is open, liquefied fuel from the cryogenic tank is allowed to enter the cryogenic pump. The switching valve described herein can be controlled to close or open to allow fluid to flow in only one direction. The shut-off valve described herein can be controlled to close or open to prevent or allow fluid to move in one or more directions.

[0045] The term “ambient temperature” as used in this article will be understood as the temperature under ambient conditions, such as room temperature of 20-22°C.

[0046] Liquefied gases or fuels such as liquid hydrogen (LH2) are stored in cryogenic tanks. Heat leaking into these tanks causes the liquid to evaporate, producing “vaporized” vapor and increasing the pressure of the gas in the headspace of the tank. Over time, the pressure buildup in the tank necessitates venting the gaseous hydrogen from the headspace to keep the cryogenic tank below its pressure limits. As an alternative to venting, the vaporization problem can be addressed by introducing a cooling load into the tank to compensate for the heat leakage. The goal of cryogenic liquid hydrogen storage is to minimize or eliminate vaporization or the loss of hydrogen as a gas from the cryogenic tank, thereby leading to improved operational efficiency.

[0047] One challenge associated with the on-site storage of LH2 in cryogenic tanks at hydrogen refueling stations is vaporization. The eventual increase in gaseous H2 in the headspace of the cryogenic tank leads to a pressure increase. Over time, the headspace pressure increases; when the pressure approaches the maximum rated pressure of the cryogenic tank, venting is necessary. Venting results in the loss of H2 due to its non-productive release into the environment, or it results in additional system components capturing and efficiently utilizing the vented H2. As used herein, the term "headspace pressure" refers to the pressure of the vapor phase of the liquefied fuel in the cryogenic tank. The term "tank pressure" as used herein refers to the pressure of the liquid phase of the liquefied fuel in the cryogenic tank. The headspace pressure and the tank pressure are equal to each other and can be used interchangeably.

[0048] Hydrogen refueling stations that store fuel as liquid hydrogen (LH2) in on-site cryogenic tanks must manage the headspace pressure within those tanks. If the pressure is too low, there is a risk of tank collapse. If the pressure is too high, gaseous hydrogen must be vented from the tank to prevent rupture. Furthermore, high headspace pressure is also associated with lower-density liquid fuels, leading to less efficient operation of the liquid pumps that deliver LH2 to downstream refueling facilities.

[0049] This disclosure provides a system such as a fuel refueling station and a method for managing headspace pressure caused by vaporization during the storage or distribution of liquefied fuels. For example, the liquefied fuel includes or is hydrogen, and the system is for storing and / or using liquid hydrogen.

[0050] According to some embodiments, the refueling station design provided in this disclosure allows for the management of headspace pressure using a submersible pump with multi-mode operating capability. The pump or pumping system is used to pump liquid hydrogen. For example, in a first mode, the pumping system may increase the headspace pressure. In a second mode, the pumping system may maintain the headspace pressure. In a third mode, the pumping system may directly vent headspace vapor to reduce the headspace pressure. Valves are used to switch between these operating modes.

[0051] A key challenge in LH2 pumping is the need for high-quality liquid at the inlet to maintain high volumetric efficiency and high-quality flow rates. This liquid quality depends on the conditions of the liquefied gas tank. To maintain high-quality liquid in the storage tank, the heat input to the cryogenic vessel must be minimized. Heat input occurs in the form of both static and dynamic heat leaks.

[0052] Static heat leakage occurs due to conductive and radiative heat transfer through the container walls, support structures, and piping. In cryogenic storage containers, a vacuum double-walled structure with multi-layered insulation can be used in the evacuated space, and low-conductivity materials can be used for the support structure. However, static heat leakage can be minimized, but not eliminated. Industrial experience with static heat flux in liquid hydrogen storage containers is based on an internal container surface area of ​​approximately 1 W / m². 2 For an 18,000-gallon liquid hydrogen storage container, this translates to approximately 200 W, or less than 1% of the normal vaporization rate (NER) per day.

[0053] Dynamic heat leakage is the heat input during pump operation. It includes mechanical energy used to overcome friction rather than increase discharge pressure, seal leaks or cross-flows, and thermodynamic non-isentropic behavior. It depends on the pump flow rate and the density of the suction liquid and is significantly influenced by pump design, such as the pump's seal and placement relative to the cryogenic tank (i.e., outside or submerged inside the cryogenic tank). Dynamic heat leakage is typically many times greater than static heat leakage. For example, the required isentropic pumping power is 34.4 kW to pressurize liquid hydrogen at a flow rate of 120 kg / hr from its normal boiling point to a discharge pressure of 900 bar. Each percentage of non-isentropic losses is 340 W, which is already greater than the typical NER of a large cryogenic tank. For external pumps, initial cooling is another major source of vaporization losses. During normal operation, the short thermal path in an external pump includes the piston shaft, the vacuum jacket housing, and the liquid hydrogen bath around the pump, which causes more heat leakage and dynamic vaporization than in a submerged pump. Vapor recirculation through the vacuum jacket pipes carries additional heat into the cryogenic tank.

[0054] The use of liquid pumps to deliver fuel during refueling operations can increase or decrease headspace pressure. During prolonged periods of inactivity, static heat leakage can cause an increase in cryogenic tank pressure. Pump operation, especially with inefficient pump designs, can also cause an increase in cryogenic tank pressure due to dynamic heat leakage. During cryogenic pump operation, energy is delivered to the tank via dynamic heat leakage, but is also removed from the cryogenic tank via discharged fluid. Furthermore, the removal of LH2 increases the headspace volume in the cryogenic tank, leading to a pressure drop. Therefore, changes in cryogenic tank pressure depend on the balance between energy outflow and heat leakage, and dynamic heat leakage is critical for maintaining low tank pressure and high liquid density.

[0055] To maintain the high volumetric efficiency of the cryogenic pump, static and dynamic heat leakage into the cryogenic tank must be minimized to maintain low cryogenic tank pressure and high liquid density. However, the headspace pressure cannot be reduced below a given threshold because it poses a risk of imploding the cryogenic tank. During high-flow-rate pumping, such as during back-to-back refueling of vehicles, the cryogenic tank pressure may drop below the desired limit. In such cases, a method for adding energy to the cryogenic tank to build up pressure is needed. A system and method, as provided in this disclosure, that can switch between pressure build-up, pressure holding, and pressure reduction modes is highly desirable.

[0056] In one aspect, the present invention provides a refueling station design that allows for the management of headspace pressure using a submersible LH2 pump with multi-mode operation capabilities. These three modes are a "pressure build-up" mode, a "pressure hold" mode, and a "pressure reduction" mode. In pressure build-up mode, the pump operates to accommodate sufficient vaporization to maintain cryogenic tank pressure during high-flow pumping, thereby preventing tank collapse. In pressure hold mode, the pump operates to remove dynamic heat leakage from the cryogenic tank along with discharged fluid to maintain headspace pressure. In pressure reduction mode, headspace vapor is directly removed to reduce headspace pressure. These modes are achieved through a separate piping configuration between the liquid pump and the rest of the system. The system can be switched between these modes using manual or automatic valves.

[0057] According to some embodiments, the switching valves described herein allow the system to switch between these operating modes. For example, in "pressure build-up" mode, dynamic heat leakage from cryogenic pump operation is redirected into the cryogenic tank to increase pressure. The headspace pressure may also partially increase during system operation due to vaporization of the liquefied fuel in the tank. In "pressure hold" mode, fluid flowing out of the cryogenic tank carries dynamic heat leakage. In "pressure reduction" mode, headspace vapor is removed to directly reduce pressure. As mentioned above, the largest heat source is dynamic heat leakage. By controlling this heat source, the mode-switching method can either add heat to the cryogenic tank to build pressure or remove this heat from the tank to reduce pressure.

[0058] A single system with a multi-mode configuration implements all the functions associated with the three modes in a controlled manner. This system provides utility in managing the pressure of the cryogenic tank. The state of the liquid is regulated to thermodynamic equilibrium with the gas in the headspace. At lower pressures, the liquid mass (determined by its density) is higher. Higher liquid mass results in more efficient pump operation; an additional benefit is the avoidance of H2 loss from the tank during venting processes associated with excessively high pressures. Switching valves, as described herein, are used to redirect the fluid path, where the heat content travels along a prescribed route as needed. Pressure build-up and pressure reduction are generally considered mutually exclusive characteristics; solutions to one of these problems necessarily exacerbate the opposite. By rerouting the fluid and dynamic heat inputs, cryogenic tank pressure management becomes feasible using the system and methods described herein.

[0059] Recent field tests have shown that the submersible pump described in U.S. Patent No. 11,149,703 can reduce headspace pressure in a tank; however, this only occurs during the pump's extended operation, and there is no indication that the headspace pressure can be actively controlled. The systems and methods provided in this disclosure can be used to actively manage several operating modes.

[0060] This disclosure also provides a method for refueling a hydrogen fuel cell vehicle, wherein hydrogen fuel is stored as LH2 in a cryogenic tank on-site, and a multi-mode pumping system is used to dispense the fuel. When the headspace pressure is below a first threshold, the pumping system operates in a first mode to increase the headspace pressure. When the headspace pressure is above the first threshold but below a second threshold, the pumping system operates in a second mode to maintain the headspace pressure. When the headspace pressure is above the second threshold, the pumping system is operated to directly vent headspace vapor, thereby reducing the headspace pressure. A controller is used to monitor the headspace status and switch between operating modes.

[0061] exist Figure 1-6 In this context, identical items are represented by the same reference numerals, and for the sake of brevity, the descriptions of the structures provided above with reference to the preceding figures will not be repeated. (See also: [reference]) Figure 1-6 The exemplary structure described in the document is used to describe Figure 7 The method described in [the document / document].

[0062] Reference Figure 1-2 An exemplary system 100, or immersion pumping system, according to some embodiments is shown. The exemplary system 100 includes a cryogenic tank 10 and a pump 40.

[0063] In some embodiments, the cryogenic tank 10 is a double-walled cryogenic tank having an outer container 12 (or outer wall) and an inner container 13 (or inner wall). The space between the two walls of containers 12 and 13 is either a vacuum or filled with insulating material.

[0064] The cryogenic tank 10 is configured to store liquefied fuel 14 therein. The cryogenic tank 10 may be an insulated tank suitable for storing liquefied fuel 14, such as liquid hydrogen, at cryogenic temperatures and pressures. In some embodiments, the liquefied fuel 14 comprises hydrogen or hydrogen vapor phase. The vapor phase 16 (vaporization) of the liquefied fuel 14 may exist above the liquid phase of the liquefied fuel 14 in the top space 18 within the inner container 13 of the cryogenic tank 10.

[0065] The pump 40 is configured to be disposed within the cryogenic tank 10 and to provide a flow of liquefied fuel from the cryogenic tank 10. The pump 40 is a submersible pump, wherein the pump inlet is submerged in the liquefied fuel 14 within the cryogenic tank 10 during use. The pump 40 is inserted into the cryogenic tank 10 and can be removed for maintenance. The pump 40 has a pump housing including an outer conduit (or pipe) 20. The pump 40 may also include an inner conduit (or pipe) 21. The outer conduit 20 itself, or a combination of the outer conduit 20 and the inner conduit 21, as a double-walled structure, may be referred to as the pump housing. The outer conduit 20 and the inner conduit 21 may be referred to as first and second lines or pipes, and have a first diameter and a second diameter greater than the first diameter. The inner conduit 21 is connected to the outer container 12 of the cryogenic tank 10. The outer conduit 20 is connected to the inner container 13 of the cryogenic tank 10. Figure 2 As shown, the outer conduit 20 has a sidewall 20a and a bottom wall 20b. The inner conduit 21 has a sidewall 21a and a bottom wall 21b. A space 29 exists between the sidewall 21a of the inner conduit 21 and the sidewall 20a of the outer conduit 20. This space 29 may be vacuum-sealed or filled with insulating material and may accommodate other conduits, such as conduits 7, 8, and 31 described herein. The pump 40 is configured to be disposed within the cryogenic tank 10. In other words, the pump 40 is insertable or inserted into the cryogenic tank 10, and in some embodiments, the cryogenic pump 40 may be removed for maintenance, except for the pump housing comprising the outer conduit 21 or the outer conduit 21 and the inner conduit.

[0066] In some embodiments, pump 40 is a single-stage, single-acting reciprocating cryogenic pump. In some embodiments, pump 40 includes a separator 17 disposed within an inner conduit 21 and coupled to a sidewall 21a, dividing the space within the inner conduit 21 into a liquid region at the bottom and a gas region at the top. The separator 17 is a seal, allowing some liquid fuel 14 to leak into the vapor space 39.

[0067] Pump 40 also includes a piston rod 22 and a piston 23, the piston being for liquefied fuels (e.g., liquid hydrogen). In some embodiments, piston 23 may have a circular shape. Piston rod 22 passes through separator 17. Piston rod 22 is connected to an external hydraulic piston 41, which may be connected to a power drive and actuator (not shown).

[0068] The pump 40 also includes a pump cylinder 27 disposed below the separator 17 and within an inner conduit 21 configured to receive a piston 23. The pump cylinder 27 is coupled to the separator 17. The sidewalls of the pump cylinder 27 define orifices 4. Within the pump cylinder 27, spaces below and above the piston 23 are designated 35 and 38, respectively; these are pump chambers and are configured to hold liquefied fuel (e.g., LH2) during operation of the pump 40.

[0069] The pump 40 also includes an isolation valve 5 and an inlet 34. The isolation valve 5 is configured to supply liquefied fuel 14 from the cryogenic tank 10 to the inlet 34.

[0070] Please refer to Figures 1 to 2 The isolation valve 5 is disposed on the bottom wall 21b of the inner pipe 21. The isolation valve 5 can be commanded (controlled) to open or close as needed. The isolation valve 5 can be actuated and controlled by an external actuator (not shown). A suitable example of the isolation valve 5 is disclosed in US2020 / 0240379, which is authorized as U.S. Patent US11,149,703. By closing the isolation valve 5, the pump housing is isolated from the inner container 13 containing liquefied fuel, allowing the pump 40 to be removed without affecting the inner container 13.

[0071] In some embodiments, the piston 23 has a front surface 23a facing the inlet 34. In the extended mode, the piston 23 moves toward the inlet 34. In the retracted mode, the piston moves further away from the inlet 34.

[0072] In some embodiments, at least one check valve 6 is disposed on a support wall 19 between the inner conduit 21a and the pump cylinder 27. In some embodiments, a check valve 24 is disposed on the bottom wall of the pump cylinder 27. Check valves 6, 24, and 26 open and close automatically. The check valves (e.g., valves 6, 24, and 26 as described herein) are one-way valves. The space at the bottom of the inner conduit 21 and below the support wall 19 is the inlet 34 of the pump 40, which is configured to draw liquefied fuel 14 (e.g., LH2) from the inner tank 13 during operation of the pump 40.

[0073] The back-side pump chamber 38 is located between the separator 17 and the support wall 19, and between the inner pipe 21 and the pump cylinder 27. Chamber 38 and chamber 36 are in fluid communication in the same annular space between the pump cylinder 27 and the inner pipe 21. This back-side pump chamber is configured to hold liquefied fuel 14 from the orifice 4 and the check valve 6. The liquefied fuel 14 in the back-side pump chamber 38 from the orifice 4 can absorb dynamic heat from the pump 40. This liquefied fuel from the back side of the piston 23 can absorb dynamic heat when the pump 40 operates in extended or retracted mode, and can be hotter than the liquefied fuel at the inlet.

[0074] The exemplary system 100 also includes a first conduit 8 fluidly connected to a vapor pump chamber 39 configured to hold vapors of liquefied fuel in the pump, and a second conduit 7 fluidly connected to a first liquid pump chamber configured to hold liquefied fuel in contact with the back side 23b of the piston 23.

[0075] like Figure 1-2 As shown, pipes 7 and 8 are fluidly connected to the side wall 21a of the inner pipe 21 of pump 40. Pipe 7 is configured to discharge liquefied fuel 14 from the liquid pump chamber 36, which serves as the bottom of pump 40. Pipe 8 is configured to discharge any gaseous fuel present in the vapor space 39. This gaseous fuel is the vapor from the liquefied fuel 14 that leaks through the separator seal 17 into the vapor chamber 39 in the upper part of the inner pipe 21 after absorbing heat from pump 40.

[0076] The upper part of pump 40 refers to the portion of pump 40 above separator 17. Steam chamber 39 can also be referred to as the upper chamber. The chamber within pump 40 below separator 17 is the liquid chamber, or lower chamber, configured to hold liquefied fuel. For ease of description, liquid pump chamber 36 is the first liquid pump chamber. Liquid pump chamber 35 can be the second liquid pump chamber. Backside pump chamber 38 is also a liquid chamber in pump 40. Chambers 38 and 36 are fluidly connected.

[0077] The exemplary system 100 also includes a discharge line 25, which is fluidly connected to the pump 40 and configured to distribute a flow of liquefied fuel out of the pump 40. Figure 1-2 As shown, liquefied fuel 14 can be pumped into the distributor via a discharge line 25 (pipeline) having a check valve 26 and being fluidly connected to a pump cylinder 27. The discharge line 25 and the check valve are located inside the inner pipe 21. The check valve 26 is one-way open. For example, as... Figure 2 As shown, in some embodiments, the discharge line 25 is fluidly connected to the bottom wall of the pump cylinder 27, allowing liquefied fuel to be pumped out when the piston 23 extends. In some embodiments, the liquefied fuel flow may be provided to a distributor and distributed to an onboard tank in a fuel cell vehicle.

[0078] Reference Figure 1 and Figure 2 According to some embodiments, exemplary system 100 includes a switching valve 30 and conduits or lines 31 configured to allow liquefied fuel 14 in liquid or vapor phase to flow from conduits 7 and 8 back to the inlet 34 of pump 40, if desired. Figure 1 and 2As shown, in some embodiments, the conduit 31 connected to the switching valve 30 is fluidly connected to the inner conduit 21 of the pump 40. The connection point of the conduit 31 is near the inlet check valve 24. The switching valve 30 is fluidly connected to a conduit 8, referred to as the first conduit, and a conduit 7, referred to as the second conduit, and is configured to allow vapors of liquefied fuel 14 in the pump 40 and liquefied fuel 14 in contact with the back side 23b of the piston 23 to flow through the conduit 31, referred to as the third conduit, to the inlet 34 of the pump 40.

[0079] Furthermore, the exemplary system 100 is configured to allow liquefied fuel 14 in its liquid or vapor phase to flow back to the cryogenic tank 10 from pipes 7 and 8. The exemplary system 100 also includes at least one isolation valve 50 or 51 fluidly connected to the first pipe, the second pipe, and the top space 18 of the cryogenic tank 10. The at least one isolation valve 50 or 51 is fluidly connected to a switching valve 30. Each of the switching valve 30 and the at least one isolation valve 50 or 51 can be opened or closed.

[0080] like Figures 1 to 2 As shown, the exemplary system 100 includes dual isolation valves 50 and 51, configured to allow liquefied fuel 14 to flow from pipes 7 and 8 back to the internal container 13 of the cryogenic tank 10 via pipe 52. Pipe 52 is fluidly connected to the internal pipe 21 of the cryogenic pump via pipe 8 in the upper gas section and pipe 7 in the lower liquid section. When switching valve 30 is closed, flow of liquefied fuel 14 into the cryogenic tank 10 occurs. When valves 50 and 51 are closed, liquefied fuel 14 from pipes 7 and 8 flows back to pump 40. In some embodiments, the two routes can coexist, and the ratio between the two routes can be adjusted.

[0081] The exemplary system 100 may also include a pressure reducing valve 53 between valves 50 and 51 to vent vapors from the top space of the cryogenic tank when needed. An venting line between switching valve 30 and valve 50 provides additional options for purging and venting.

[0082] The exemplary system 100 may also include one or more controllers 60 for controlling the steps and components as described herein. Controllers 60 may be electrically connected to relevant components in system 100 (e.g., valves 30, 50, and 51, exhaust line 59). Controllers 60 may include one or more processors and at least one tangible, non-transitory machine-readable medium encoded with one or more programs to be executed by one or more processors. Controllers 60 are configured to coordinate with each component to control operation, such as operating the cryogenic pump in different modes, controlling liquefied fuel storage, and refueling a vehicle. Controllers 60 are connected to cryogenic tank 10. For example, controllers 60 may be connected to an inner container 13 via connection 64 and configured to test the headspace pressure within the inner container 13. Controllers 60 are used to monitor headspace conditions and switch between operating modes as described herein. For example, controllers 60 are configured to measure the headspace pressure or temperature inside cryogenic tank 10 and control at least one isolation valve 50 or 51, switching valve 30, and / or isolation valve 5, such that the system operates in different operating modes based on headspace pressure or temperature. The exemplary system 100 is configured to operate in one of three operating modes, including a pressure increase mode, a pressure hold mode, and a pressure decrease mode, to increase, hold, or decrease the pressure in the top space within the cryogenic tank, respectively.

[0083] The aforementioned components can have any suitable dimensions. For example, the diameter of the inner conduit 21 of pump 40 can be in the range of 25 cm to 50 cm. The diameter of the outer conduit 20 of pump 40 can be in the range of 35 cm to 70 cm. Pipes and conduits 7, 8, 31, 25 and 52 can have any suitable dimensions, for example, having a diameter in the range of 1 cm to 15 cm. In some embodiments, conduit 52 has an inner diameter of approximately 2.5 cm.

[0084] When the headspace pressure (P) is below a first pressure threshold (P1), the pressure increase mode described above can be used. In some embodiments, in the pressure increase mode, switching valve 30 is closed and at least one isolation valve 50 or 51 is open. If the system includes, as Figure 1-2 The two isolation valves 50 and 51 shown are both open in the pressure increase mode. Isolation valve 5 can be closed or opened.

[0085] refer to Figure 3 An exemplary system 100 in retracted mode is shown. Figure 2 The chambers and spaces are marked. The case where switching valve 30 is closed or the exemplary system does not have switching valve 30 is described first.

[0086] When the piston 23 of the single-stage, single-acting reciprocating cryogenic pump 40 retracts during the suction stroke, the isolation valve 5 and check valve 24 open, while the check valve 6 closes. Liquid liquefied fuel 14 from the cryogenic tank 10 enters the pump chamber 35. Liquefied fuel 14 from the chamber 38 behind the piston 23 exits through the opening 4 into the chamber 36 and flows through the pipe 7.

[0087] When the switching valve 30 is closed, or when the exemplary system does not have the switching valve 30, the liquefied fuel 14 from chambers 38 and 36 flows through valves 50 and 51 and enters the inner container of the cryogenic tank 10 through the opening of pipe 52.

[0088] Gas line 8 is configured to discharge vapor from vapor space 39 on the upper portion of the pump housing to the top space of cryogenic tank 10, and to provide pressure equalization between vapor space 39 on the upper portion of the pump housing and liquid spaces (e.g., pump chambers 36 and 38) at the bottom portion of the pump housing. Figure 3 As shown, when the switching valve 30 is closed, the vapor phase from the vapor space 39 flows through the gas line 8 to the top space 18. The vapor from the vapor space 39 and the liquid phase from the back chamber 38 behind the piston 23 can have a higher temperature than the liquefied fuel 14 in the cryogenic tank 10 because they absorb dynamic heat from the pump 40.

[0089] refer to Figure 4 An exemplary system 100 in extended mode is shown. Figure 2 The chambers and spaces are marked. The case where switching valve 30 is closed or the exemplary system does not have switching valve 30 is described first.

[0090] When piston 23 extends during compression, check valve 24 closes, forcing liquefied fuel out of the pump chamber through check valve 26 to discharge line 25.

[0091] In the arrangement where the switching valve 30 is not present or is closed, any sealing leaks around piston 23, the liquid behind piston 23, and the frictional heating gained in the pump chamber and around the piston are returned to the cryogenic tank via line 52. This operating mode is a pressure build-up mode because it adds heat to the cryogenic tank 10 during operation and increases the headspace pressure. The headspace pressure in the gas phase 16 is approximately the same as the cryogenic tank pressure in the liquid phase 14.

[0092] Return to reference Figure 3-4 The switching valve 30, together with the pipeline 31, can be configured to redirect liquefied fuel fluid with dynamic heat (e.g., the vapor phase from pipeline 8 and the liquid phase from pipeline 7) back to the inlet of the pump 40, which may be near the inlet check valve 24.

[0093] In pressure holding mode, switching valve 30 is open, while isolation valve 50 and / or isolation valve 51 are closed. Isolation valve 5 is open during this operating mode. Figure 3 As shown, during the suction stroke, when piston 23 retracts, check valve 24 opens and receives fluid from cryogenic tank 10 (i.e., the inner container 13 of cryogenic tank 10) via isolation valve 5. Isolation valve 5 is open while check valve 6 is closed. Check valve 24 also allows fluid from liquefied fuel 14 from line 31. Liquefied fuel 14 (which has absorbed heat) from chamber 38 behind piston 23 exits through opening 4 to chamber 36 and flows through pipe 7. The liquefied fuel fluid (e.g., liquid from pipe 7 and vapor from pipe 8) returns to pump 40 via switching valve 30 and mixes with liquefied fuel 14 from cryogenic tank 10.

[0094] like Figure 4 As shown, in pressure holding mode, when pump 40 is in extension mode, piston 23 extends towards the bottom of pump 40. Isolation valve 5 and check valve 6 are open, while check valve 24 is closed. Liquefied fuel 14, including fluid from line 31, exits pump 40 from check valve 26 and discharge line 25. Some cold liquefied fuel 14 from check valve 6 and within chamber 36 can be drawn into chamber 38 behind piston 23 through opening 4.

[0095] The energy from the dynamic heat leakage contained in the fluid from line 31 enters pump chamber 35 and subsequently leaves pump 40 through check valve 26 and drain line 25. Therefore, no dynamic heat input is introduced into cryogenic tank 10. Although static heat leakage still exists, the removal of liquid from cryogenic tank 10 increases the headspace volume and reduces its pressure. The enthalpy of the liquid is another source of heat removal from cryogenic tank 10. The balance between static heat leakage and liquid removal leads to... Figure 3-4 The pressure holding mode shown represents the stable cryogenic tank pressure.

[0096] This pressure holding mode can be used when the headspace pressure (P) is equal to or higher than a first pressure threshold (P1) and lower than a second pressure threshold (P2). The exemplary system operates in pressure holding mode when the headspace pressure (P) is within the range of P1 to P2.

[0097] Reference Figure 5-6 An exemplary system 100 operating in a pressure reduction mode is shown. Figure 5 As shown, pump 40 is in retracted mode. Figure 6 As shown, pump 40 is in extended mode, with the piston extended. In pressure reduction mode, switching valve 30 is open, and isolation valves 50 and 51 are open. Isolation valve 5 is closed.

[0098] When the headspace pressure (P) exceeds the second pressure threshold (P2), a pressure reduction is desired to prevent the discharge of vapors from the headspace 18 of the cryogenic tank 10. For example... Figure 5 As shown, isolation valve 5 is closed, while valves 50 and 51 are open. Switching valve 30 is also open, establishing a flow path from the top space 18 of the cryogenic tank 10 to the pump inlet near check valve 24. Similarly... Figure 5 As shown, the other components (e.g., check valve 6 (closed), check valve 24 (open), and lines 7 and 8) operate in the same manner as... Figure 3 Similar to the example shown. The top space vapor 16 flows into the pump 40 and can mix with the liquefied fuel 14 therein.

[0099] like Figure 6 As shown, pump 40 is in extended mode, while isolation valve 5 is closed. Valves 50 and 51 are open. Switching valve 30 and line 31 are open. Other components (e.g., check valve 6 (open), check valve 24 (closed), and lines 7, 8) operate in the same manner. Figure 4 Similar to the example shown. Topspace vapor 16 or a mixture of topspace vapors is pumped out through check valve 26 and line 25.

[0100] like Figures 5 to 6 As shown, in this pressure reduction mode, the top space vapor 16 is pumped out of the cryogenic tank 10 to directly reduce pressure.

[0101] As one of the significant benefits provided by the exemplary system 100, pump 40 is capable of pumping both liquid and vapor forms of liquefied fuel. The flow rate in this vapor pumping mode is lower than the pump design flow rate for liquid liquefied fuel. For example, the saturated liquid and vapor densities of hydrogen at 0.8 MPa are 52.4 and 12.1 kg / m³, respectively. 3 The mass flow rate of hydrogen pumped by steam is only about 23% of that pumped by liquid.

[0102] To promote vapor compression, it is desirable to activate the pressure reduction mode when the discharge pressure is relatively low, such as at the start of vehicle refueling. The control logic can be implemented to manage the timing and duration of mode switching.

[0103] During back-to-back vehicle refueling, a significant amount of liquid is drawn from cryogenic tank 10, which can cause a decrease in tank pressure, depending on the liquid level, liquid density, tank volume, and initial tank pressure. For example, for a tank at 70 kg / m³... 3 At the nominal liquid hydrogen density and with a pump flow rate of 240 kg / hr at 80% liquid level and an initial tank pressure of 0.5 MPa, the expected pressure drop rate under continuous operation is 0.011 MPa / hr. At lower liquid levels, the headspace volume is larger, and the pressure drop rate is smaller.

[0104] Reference Figure 1-6In some embodiments, the switching valve 30 is located outside the pump. The pump 40 has a pump housing with a double-walled structure. The first pipe 8, the second pipe 7, and the third pipe 31 are disposed between the two walls of the pump housing.

[0105] exist Figure 1-6 For illustrative purposes only, only one pump 40 is included. In some embodiments, there may be more than one pump 40 disposed within the cryogenic tank 10, such as two or more such submersible liquid pumps. Each pump 40 may be independent and have its own inlet. Alternatively, the two or more submersible liquid pumps 40 may share the same inlet 34. The multiple pumps 40 may be connected in parallel and then coupled to the first conduit 8, the second conduit 7, and the third conduit 31, respectively.

[0106] In one aspect, as described above, this disclosure provides an exemplary system 100 for refueling hydrogen fuel, such as a hydrogen refueling station. System 100 includes a cryogenic tank 10 configured to store liquefied fuel 14 as hydrogen therein, and at least one pump 40 configured to be disposed within the cryogenic tank 10. Pump 40 is configured to provide a flow of liquefied fuel 14 from the cryogenic tank 10. Pump 40 has a piston 23, an inlet 34, and an isolation valve 5 configured to supply liquefied fuel 14 from the cryogenic tank 10 to the inlet 34. Piston 23 has a front side 23a facing the inlet 34 and a back side 23b opposite the front side.

[0107] The system 100 also includes a first conduit 8 fluidly connected to a vapor pump chamber 39 configured to hold vapors of liquefied fuel in pump 40, and a second conduit 7 fluidly connected to a first liquid pump chamber 36 configured to hold liquefied fuel on the back side 23b of contact piston 23.

[0108] System 100 also includes a switching valve 30 fluidly connected to the first conduit 8 and the second conduit 7. The switching valve 30 is configured to allow vapors of liquefied fuel in pump 40 and liquefied fuel on the back side of contact piston 23 to flow through a third conduit 31 to the inlet of pump 40. System 100 also includes at least one isolation valve 50 or 51 fluidly connected to the first conduit 8, the second conduit 7, the cryogenic tank 10, and the switching valve 30.

[0109] System 100 may further include a controller 60 connected to the cryogenic tank 10, the at least one isolation valve 50 or 51, and the switching valve 30. The controller 60 is configured to actuate the at least one isolation valve 50 or 51, the switching valve 30, and / or the isolation valve 5 to operate system 100 in one of three operating modes based on the headspace pressure or temperature in the cryogenic tank 10. These three operating modes include a pressure increase mode, a pressure hold mode, and a pressure decrease mode.

[0110] The controller 60 may include one or more processors and at least one tangible, non-transitory machine-readable medium encoded with one or more programs, which will be executed by the one or more processors to control components of the system. For example, the controller 60 may be configured to measure headspace pressure or temperature and actuate the at least one isolation valve 50 or 51, switching valve 30, and / or isolation valve 5.

[0111] The exemplary system 100 may also include a dispenser in a refueling station. The exemplary system 100 can be integrated for refueling a fuel cell vehicle with hydrogen. The dispenser is configured to receive a flow of liquefied fuel 14 from line 25 and distribute it as gaseous fuel to a receiving fuel tank, such as a vehicle's onboard fuel tank. The refueling station may also include a heat exchanger for converting the liquefied fuel 14 into gaseous fuel to be dispensed. The gaseous fuel may be under increased pressure prior to dispensing. In some embodiments, the pump may compress the liquefied fuel to increase its pressure during pumping operations.

[0112] refer to Figure 7 This disclosure provides an exemplary method 200 for using the system 100 as described above and also generally described below.

[0113] At step 202, liquefied fuel 14 is provided and stored in cryogenic tank 10. In some embodiments, the liquefied fuel 14 comprises hydrogen or hydrogen.

[0114] At step 204, the pressure and / or temperature of the top space inside the cryogenic tank 10 are measured. The liquid fill level in the cryogenic tank 10 may also be measured.

[0115] In step 206, based on the headspace pressure and / or temperature, an operating mode for the system to be operated is determined. This operating mode is one of three operating modes, including a pressure increase mode, a pressure hold mode, and a pressure decrease mode.

[0116] In step 208, at least one of the isolation valve, switching valve, and shut-off valve is actuated to operate the system in the operating mode.

[0117] In some embodiments, when the headspace pressure is below a first threshold pressure (P1), a pressure increase mode is determined and activated. When the headspace pressure is within the range from the first threshold pressure (P1) to a second threshold pressure (P2), where P2 > P1, a pressure hold mode is determined and activated. When the headspace pressure is above the second threshold pressure (P2), a pressure decrease mode is determined and activated.

[0118] In some embodiments, the first threshold pressure (P1) may be about 0.1 MPa. The second threshold pressure (P2) may be a pressure in the range of 0.2 MPa to 0.5 MPa. For example, P1 is about 0.1 MPa and P2 is about 0.5 MPa. When the headspace pressure (P) is in the range of about 0.1 MPa to about 0.5 MPa, in some embodiments, the system operates in a pressure holding mode. When the headspace pressure is above 0.5 MPa, the system is in a pressure reducing mode.

[0119] In some embodiments, the operating mode can also be determined based on the temperature in the cryogenic tank 10. For example, when the headspace temperature is below a first threshold temperature (T1), a pressure increase mode is determined and activated. When the headspace temperature is in the range from the first threshold temperature (T1) to a second threshold temperature (T2), where T2 > T1, a pressure hold mode is determined and activated. When the headspace temperature is above the second threshold temperature (T2), a pressure decrease mode is determined and activated. No dynamic heat input is introduced into the cryogenic tank, and the cryogenic tank pressure decreases with pump operation.

[0120] If the liquefied fuel level in the tank is too low or too high, the controller 60 of system 100 can provide a warning. The operating mode may differ when the cryogenic tank is near full or empty, compared to when the level is within the normal range.

[0121] In some embodiments, in the pressure increase mode, switching valve 30 is closed and isolation valves 50 and 51 are open. Isolation valve 5 is open. In the pressure hold mode, switching valve 30 is open, at least one isolation valve 50 or 51 is closed, and isolation valve 5 is open. In the pressure decrease mode, switching valve 30 is open, isolation valves 50 and 51 are open, and isolation valve 5 is closed.

[0122] At step 210, the liquefied fuel stream from cryogenic tank 10 is pumped from pump 40 to discharge line 25. In some embodiments, the liquefied fuel comprises hydrogen, and the method is used to refuel a fuel cell vehicle. The liquefied fuel stream is pumped to a distributor and distributed into the onboard tank of the fuel cell vehicle. In step 210, a distribution cycle is operated to refuel the vehicle. The hydrogen fuel can be distributed into the vehicle at a suitable pressure (e.g., 35 MPa or 70 MPa). Compressed hydrogen can be at a temperature of -40°C and distributed via a refueling distribution cycle at a temperature of, for example, -20°C.

[0123] Steps 204, 206, 208, and 210 can be repeated for additional refueling or necessary filling. In some embodiments, an operating mode is determined for refueling hydrogen into more than two fuel cell vehicles.

[0124] During the idle time between two refueling events, the pressure or temperature inside the cryogenic tank is also monitored, and operating modes are identified and activated if necessary. For example, after a prolonged idle time, the headspace pressure may increase due to static heat leakage. A pressure reduction mode can be activated to reduce the pressure.

[0125] As mentioned above, multiple pumps can be installed inside the cryogenic tank and can operate simultaneously. A pump can have its own inlet, or multiple pumps can share a single inlet.

[0126] Vaporization losses in system 100 are minimized. If it is necessary to discharge vaporized gas, equipment for recovering vaporized gas can be used in some embodiments. The system may include a recovery subsystem. For example, the vaporized gas may be cooled to a liquid state, and this recovered liquefied fuel is fed back to a cryogenic tank. Alternatively, the discharged vaporized gas (e.g., hydrogen) may be compressed by a compressor in the recovery subsystem to an increased pressure of over 35 MPa. The compressed gas is delivered to a cascade pipe storage tank for subsequent delivery to the vehicle during refueling.

[0127] The systems and methods provided in this disclosure offer numerous advantages as described herein. For example, in some embodiments, this disclosure provides a system for hydrogen storage and refueling. Benefits include the ability to operate in multiple modes based on headspace pressure, manage headspace pressure, and minimize the loss of liquefied fuels. The system minimizes or eliminates the loss of liquefied fuels such as hydrogen, or has minimized hydrogen vaporization losses.

[0128] The methods and systems described herein can be embodied, at least in part, in the form of computer-implemented processes and apparatus for performing these processes. The disclosed methods can also be embodied, at least in part, in the form of tangible, non-transient machine-readable storage media encoded with computer program code. The media may include, for example, RAM, ROM, CD-ROM, DVD-ROM, BD-ROM, hard disk drive, flash memory, or any other non-transient machine-readable storage medium or any combination of these media, wherein when the computer program code is loaded into and executed by the computer, the computer becomes an apparatus for performing the method. The methods can also be embodied, at least in part, in the form of a computer, in which computer program code is loaded into and / or executed, such that the computer becomes an apparatus for performing the method. When implemented on a general-purpose processor, computer program code segments configure the processor to create specific logic circuits. The methods can optionally be implemented, at least in part, in a digital signal processor formed by an application-specific integrated circuit for performing the methods. The computer or control unit can be operated remotely using a cloud-based system.

[0129] Although the subject matter has been described with reference to exemplary embodiments, it is not limited thereto. Rather, the appended claims should be interpreted broadly to include other variations and embodiments that may be made by those skilled in the art.

Claims

1. A system comprising: A cryogenic tank, the cryogenic tank being configured to store liquefied fuel therein; A pump configured to be disposed inside the cryogenic tank and to provide a flow of liquefied fuel from the cryogenic tank, the pump having a piston, an inlet, and an isolation valve configured to supply the liquefied fuel to the inlet; A first conduit is fluidly connected to a vapor pump chamber configured to hold vapor of the liquefied fuel in the pump; A second conduit is fluidly connected to a first liquid pump chamber, which is configured to maintain liquefied fuel in contact with the back side of the piston. as well as A switching valve, fluidly connected to the first and second conduits, is configured to allow vapors of the liquefied fuel in the pump and the liquefied fuel in contact with the back side of the piston to flow through a third conduit to the inlet of the pump. At least one isolation valve, the at least one isolation valve being fluidly connected to the first conduit, the second conduit, and the top space of the cryogenic tank. The at least one isolation valve is fluidly connected to the switching valve.

2. The system of claim 1, wherein, The system is configured to operate in one of three modes: a pressure increase mode, a pressure hold mode, and a pressure decrease mode, to increase, hold, or decrease the pressure in the top space within the cryogenic tank, respectively.

3. The system of claim 2, wherein, The system also includes a controller connected to the cryogenic tank, the at least one isolation valve, and the switching valve, and configured to measure the headspace pressure within the cryogenic tank and control the at least one isolation valve, the switching valve, and / or the isolation valve such that the system operates in one of the three operating modes based on the headspace pressure.

4. The system of claim 2, wherein in the pressure increase mode, the switching valve is closed and the at least one isolation valve is open.

5. The system of claim 2, wherein in the pressure holding mode, the switching valve is open, the at least one isolation valve is closed, and the isolation valve is open.

6. The system of claim 2, wherein in the pressure reduction mode, the switching valve is open, the at least one isolation valve is open, and the isolation valve is closed.

7. The system of claim 1, wherein the liquefied fuel is liquid hydrogen, and the system is a hydrogen fuel refueling system.

8. The system of claim 1, wherein, The system also includes a discharge line fluidly connected to the pump and configured to distribute the liquefied fuel flow out of the pump.

9. The system of claim 1, wherein, The switching valve is located outside the pump, the pump has a pump housing with a double-wall structure, and the first pipe, the second pipe and the third pipe are located between the two walls of the pump housing.

10. The system of claim 1, wherein the pump comprises two or more submersible liquid pumps disposed within the cryogenic tank.

11. The system of claim 10, wherein, Each pump has a corresponding inlet, or the two or more submerged liquid pumps share a single inlet; and the two or more submerged liquid pumps are connected in parallel to the first pipe, the second pipe and the third pipe, respectively.

12. A hydrogen fuel refueling system, comprising: A cryogenic tank configured to store a liquefied fuel therein, wherein the liquefied fuel is hydrogen; A pump configured to be disposed inside the cryogenic tank and to provide a flow of liquefied fuel from the cryogenic tank, the pump having a piston, an inlet, and an isolation valve configured to supply the liquefied fuel to the inlet, wherein the piston has a front side facing the inlet and a back side opposite to the front side; A first conduit is fluidly connected to a vapor pump chamber configured to hold vapor of the liquefied fuel in the pump; A second conduit is fluidly connected to a first liquid pump chamber, the first liquid pump chamber being configured to maintain the liquefied fuel in contact with the back side of the piston; A switching valve, fluidly connected to the first conduit and the second conduit, is configured to allow the vapor of the liquefied fuel in the pump and the liquefied fuel in contact with the back side of the piston to flow through a third conduit to the inlet of the pump; At least one isolation valve, said at least one isolation valve being fluidly connected to the first conduit, the second conduit, the cryogenic tank, and the switching valve; and A controller, connected to the cryogenic tank, the at least one isolation valve, and the switching valve, and configured to actuate the at least one isolation valve, the switching valve, and / or the isolation valve based on the top space pressure in the cryogenic tank, so as to operate the system in one of three operating modes, including a pressure increase mode, a pressure hold mode, and a pressure decrease mode.

13. The system of claim 12, wherein the controller comprises one or more processors and at least one tangible, non-transitory machine-readable medium encoded with one or more programs, the one or more programs being executed by the one or more processors to measure the headspace pressure and actuate the at least one isolation valve, the switching valve, and / or the isolation valve.

14. A method of using the system of claim 1, comprising: Provides liquefied fuel stored in cryogenic tanks; Measure the pressure in the top space inside the cryogenic tank; Based on the top space pressure, a working mode of the system to be operated is determined, which is one of three working modes including pressure increase mode, pressure hold mode and pressure decrease mode; Actuate at least one of the at least one isolation valve, the switching valve, and the isolation valve to operate the system in the operating mode; as well as The liquefied fuel stream is pumped out from the cryogenic tank and then pumped from the pump to the discharge line.

15. The method of claim 14, wherein, The steps of determining an operating mode and actuating at least one of the at least one isolation valve, the switching valve, and the isolation valve are performed by a controller connected to the cryogenic tank, the at least one isolation valve, and the switching valve.

16. The method of claim 14, wherein When the pressure in the headspace is lower than the first threshold pressure, the pressure increase mode is determined and activated; When the headspace pressure is within the range of the first threshold pressure to the second threshold pressure, the pressure holding mode is determined and activated, wherein the second threshold pressure > the first threshold pressure; or When the headspace pressure is higher than the second threshold pressure, the pressure reduction mode is determined and activated.

17. The method of claim 14, wherein, In the pressure increase mode, the switching valve is closed and the at least one isolation valve is opened.

18. The method of claim 14, wherein, In the pressure holding mode, the switching valve is open, the at least one isolation valve is closed, and the isolation valve is open.

19. The method of claim 14, wherein in the pressure reduction mode, the switching valve is open, the at least one isolation valve is open, and the isolation valve is closed.

20. The method of claim 14, wherein the liquefied fuel comprises hydrogen, and the method is used to refuel a fuel cell vehicle with hydrogen.

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