A cold energy recovery system and control method for a liquid hydrogen refueling station

Abstract

This invention discloses a cold energy recovery system and control method for a liquid hydrogen refueling station. The cold energy recovery system includes a liquid hydrogen pump and a gaseous hydrogen buffer tank. A cold energy recovery device is installed between the liquid hydrogen pump and the gaseous hydrogen buffer tank. The cold energy recovery device includes at least one stage of thermoacoustic motor and at least one stage of pulse tube refrigerator. The thermoacoustic motor can recover the cold energy released by the liquid hydrogen flowing through it and drive the pulse tube refrigerator for cooling. In this invention's cold energy recovery system, the cryogenic fluid absorbs heat after flowing through the cold energy recovery device and then enters the gaseous hydrogen buffer tank for storage. The thermoacoustic motor in the cold energy recovery device is driven by the cold energy of the cryogenic fluid. Simultaneously, the thermoacoustic motor converts the cold energy into acoustic work, which is then transferred to the pulse tube refrigerator for cooling. This high conversion efficiency achieves efficient cold energy recovery and effectively recovers the cold energy lost during the heating process of the cryogenic fluid.

Description

Technical Field

[0001] This invention relates to the field of liquid hydrogen refueling technology, and more specifically, to a cold energy recovery system and control method for a liquid hydrogen refueling station. Background Technology

[0002] Hydrogen energy boasts advantages such as cleanliness, safety, efficiency, and sustainable development, and is considered one of the most promising clean energy sources of the 21st century. Hydrogen refueling stations, as key supporting facilities for hydrogen fuel cell vehicles, are the foundation for the development of the hydrogen energy industry chain. Hydrogen refueling stations can generally be divided into high-pressure gaseous hydrogen refueling stations and liquid hydrogen refueling stations. In high-pressure gaseous hydrogen refueling stations, hydrogen is pressurized and stored in high-pressure hydrogen storage tanks (cylinders) using a compressor, while in liquid hydrogen refueling stations, hydrogen is stored in a cryogenic liquid hydrogen state in liquid hydrogen Dewar flasks. Compared to high-pressure gaseous hydrogen refueling stations, liquid hydrogen refueling stations have the advantages of higher hydrogen storage density, superior hydrogen quality, higher filling efficiency, and better safety, making them the main direction of development.

[0003] The general process for liquid hydrogen refueling involves transporting liquid hydrogen from a liquid hydrogen dewar to a high-pressure vaporizer via a liquid hydrogen booster pump. In the high-pressure vaporizer, the liquid hydrogen absorbs heat from the environment and naturally vaporizes, then is refueled using a hydrogen dispenser. This vaporization process releases a significant amount of cold energy. If this cold energy can be recovered and reused in the liquid hydrogen refueling industry chain, the cost of the industry chain can be significantly reduced. Therefore, how to recover and effectively utilize this cold energy has always been a research hotspot in the field of cold energy recovery.

[0004] CN113531388A provides a liquid hydrogen refueling station cold energy recovery and utilization system and method. In this system, a heat exchange pipeline is connected in parallel between the liquid hydrogen pressurization input pipeline and the ambient temperature vaporizer; a recovery and utilization pipeline is connected between the heat exchange pipeline and the output end. In this method, the liquid hydrogen first exchanges heat with the refrigerant, and the cooled refrigerant enters the water tank of the chiller unit. The heat exchange coil cools the refrigerant in the water tank. After the refrigerant temperature rises, it circulates back to the heat exchanger to exchange heat with the liquid hydrogen again. The cooled refrigerant pre-cools the hydrogen being injected through the heat exchanger. After the refrigerant absorbs heat from the hydrogen and its temperature rises, it returns to the water tank for further cooling.

[0005] Chinese patent application CN115507296A provides a liquid hydrogen refueling station system for recovering BOG (Borosilicate Gas). In this system, the BOG hydrogen produced by the pre-cooling process undergoes five-stage segmented cooling via a first BOG recovery branch and a reliquefaction pipeline. The BOG hydrogen from the station's liquid hydrogen storage tank undergoes three-stage segmented cooling via a second BOG recovery branch and a reliquefaction pipeline for BOG reliquefaction, thereby achieving complete recovery and efficient storage of BOG hydrogen.

[0006] Nevertheless, in practice, there is still the problem of failing to effectively recover and utilize the cold energy from liquid hydrogen vaporization when recovering liquid hydrogen. Summary of the Invention

[0007] The purpose of this invention is to provide a liquid hydrogen refueling station cold energy recovery system that can effectively recover and utilize the cold energy of a liquid hydrogen refueling station.

[0008] To achieve the above objectives, a first aspect of the present invention provides a cold energy recovery system, including a liquid hydrogen pump and a gaseous hydrogen buffer tank, wherein a cold energy recovery device is provided between the liquid hydrogen pump and the gaseous hydrogen buffer tank, the cold energy recovery device including at least one stage thermoacoustic engine and at least one stage pulse tube refrigerator, wherein the thermoacoustic engine is capable of recovering the cold energy released by the liquid hydrogen flowing through the thermoacoustic engine and driving the pulse tube refrigerator to perform refrigeration.

[0009] Optionally, the thermoacoustic engine includes a resonant tube and a cold-end heat exchanger, a first regenerator, and a hot-end heat exchanger connected in sequence toward the resonant tube; the resonant tube is connected to the cylinder of the pulse tube refrigerator so that the oscillation generated by the thermoacoustic engine is transmitted to the cylinder of the refrigerator via the resonant tube.

[0010] Optionally, one end of the cold-end heat exchanger is connected to the outlet end of the liquid hydrogen pump, and the other end is connected to the gaseous hydrogen buffer tank.

[0011] Optionally, a cold head, a pulse tube, and a room temperature heat exchanger are sequentially installed in the refrigerator cylinder. A second regenerator is fitted on the outer wall of the pulse tube. The end of the cold head is connected to the output end of the room temperature heat exchanger through the second regenerator. The pulse tube is connected to a phase adjustment mechanism, which includes compressor pistons symmetrically arranged in the refrigerator cylinder housing. The compressor pistons are interconnected to form a compression chamber. A non-area-difference discharge device and a support leaf spring fixedly connected to the non-area-difference discharge device are symmetrically arranged in the compression chamber. The non-area-difference discharge devices form an expansion chamber, and the non-area-difference discharge devices can reciprocate under the action of acoustic power transmitted to the refrigerator cylinder through the resonant tube.

[0012] Optionally, the cold energy recovery system further includes a liquid hydrogen storage tank, in which the cold head is placed; or the cold end of the cold head is connected to a cold finger, which is placed in the liquid hydrogen storage tank.

[0013] Optionally, the thermoacoustic engine is one of a standing wave thermoacoustic engine, a traveling wave thermoacoustic engine, and a hybrid standing wave and traveling wave thermoacoustic engine; the operating temperature range of the thermoacoustic engine is 20-300K; and the power output of the thermoacoustic engine is 3MJ / kgH2.

[0014] Optionally, the pulse tube refrigerator is a single-stage pulse tube refrigerator or a multi-stage pulse tube refrigerator; the no-load cooling temperature of the pulse tube refrigerator is 5-10K.

[0015] A second aspect of the present invention provides a control method for a liquid hydrogen refueling station with a cold energy recovery system, the control method comprising:

[0016] Detect the pressure of the gaseous hydrogen buffer tank;

[0017] When the pressure in the gaseous hydrogen buffer tank exceeds the preset pressure, the cold energy recovery device and the liquid hydrogen pump are activated sequentially; the thermoacoustic engine is controlled to recover cold energy and drive the pulse tube refrigerator to operate; and...

[0018] When the pressure of the gaseous hydrogen buffer tank is less than or equal to the preset pressure, the liquid hydrogen pump is controlled to deliver hydrogen to the gaseous hydrogen buffer tank.

[0019] Optionally, when the hydrogen dispenser receives a refueling request, it detects the hydrogen concentration of the hydrogen dispenser and the pressure of the liquid hydrogen storage tank; when the hydrogen concentration of the hydrogen dispenser and the pressure of the liquid hydrogen storage tank meet preset conditions, it detects the pressure of the gaseous hydrogen buffer tank.

[0020] Optionally, the mass flow rate of the liquid hydrogen pump during operation is 5-20 kg / min; the refueling rate of the hydrogen dispenser is 3-20 kg / min.

[0021] Through the above technical solution, the cold energy recovery system of the present invention eliminates the vaporizer conventionally used in liquid hydrogen refueling stations. The cryogenic fluid absorbs heat by flowing through the cold energy recovery device and then enters the gaseous hydrogen buffer tank for storage. The thermoacoustic engine in the cold energy recovery device is driven by the cold energy of the cryogenic fluid. At the same time, the thermoacoustic engine converts the cold energy into acoustic power and then transmits it to the pulse tube refrigerator for cooling. The conversion efficiency is high, realizing the efficient recovery of cold energy and effectively recovering the cold energy lost during the heating process of the cryogenic fluid.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0024] Figure 1 This is a schematic diagram of a liquid hydrogen refueling station cold energy recovery system according to an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of a standing wave thermoacoustic engine according to an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the structure of a traveling wave thermoacoustic engine according to an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the structure of a pulse tube refrigerator according to an embodiment of the present invention.

[0028] Figure 5 This is a flowchart of a control method for a liquid hydrogen refueling station according to an embodiment of the present invention. Detailed Implementation

[0029] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0030] A typical form of hydrogen refueling at a liquid hydrogen refueling station involves pressurizing liquid hydrogen in a liquid hydrogen dewar through a liquid hydrogen pump to a high-pressure vaporizer, and then refueling the gas using a hydrogen dispenser. This refueling process results in significant energy loss. Since the gas source for a liquid hydrogen refueling station is externally supplied liquid hydrogen, and liquefying gaseous hydrogen requires a large amount of energy, the inventors have proposed a cold energy recovery system that can fully recover and utilize the cooling energy of a liquid hydrogen refueling station.

[0031] To achieve the above objectives, the present invention provides a cold energy recovery system, such as... Figure 1 As shown, the cold energy recovery system includes a liquid hydrogen storage tank 1, a liquid hydrogen pump 2, a gaseous hydrogen buffer tank 4, and a hydrogen dispenser 5. A cold energy recovery device is installed between the liquid hydrogen pump 2 and the gaseous hydrogen buffer tank 4. The cold energy recovery device includes at least one stage of thermoacoustic engine and at least one stage of pulse tube refrigerator. The thermoacoustic engine can recover the cold energy released by the liquid hydrogen flowing through it and drive the pulse tube refrigerator for cooling.

[0032] In this invention, cryogenic liquid hydrogen is stored in a vacuum Dewar, the volume of which is 3-10 m³. 3 The liquid hydrogen pump is an immersion type with a mass flow rate of 5-20 kg / min.

[0033] Specifically, the liquid hydrogen storage tank is equipped with an inlet for external liquid hydrogen supply and an outlet for releasing BOG.

[0034] It is important to note that all pipelines and equipment in a liquid hydrogen refueling station must be insulated.

[0035] The cold energy recovery system of this invention eliminates the vaporizer conventionally used in liquid hydrogen refueling stations. Liquid hydrogen flows through the cold energy recovery device, absorbs heat, and then enters the gaseous hydrogen buffer tank for storage. The thermoacoustic engine in the cold energy recovery device is driven by the cold energy of the liquid hydrogen. At the same time, the thermoacoustic engine converts the cold energy into acoustic power and then transmits it to the pulse tube refrigerator for cooling. The conversion efficiency is high, realizing the efficient recovery of cold energy and effectively recovering the cold energy lost during the heating process of cryogenic fluids.

[0036] Thermoacoustic effect is a physical phenomenon in which acoustic self-excited oscillations are induced by the interaction of heat and sound between heat and solid media in a compressible medium (usually a gas). This principle can be used to convert thermal energy into pressure fluctuations, thereby achieving the conversion of thermal energy into mechanical energy. Based on this principle, thermoacoustic engines can also recover cold energy, achieving the conversion of cold energy into mechanical energy.

[0037] Depending on the sound field, thermoacoustic engines are classified into standing wave thermoacoustic engines, traveling wave thermoacoustic engines, and hybrid standing wave and traveling wave thermoacoustic engines. In a traveling wave sound field, the velocity wave and pressure wave are in phase, while in a standing wave sound field, they are 90° out of phase.

[0038] In this invention, the thermoacoustic engine is one of a standing wave thermoacoustic engine, a traveling wave thermoacoustic engine, and a standing wave-traveling wave hybrid thermoacoustic engine.

[0039] When using different types of thermoacoustic engines, the shape of the resonant tube must be matched accordingly. For example, when using a traveling wave thermoacoustic engine, the resonant tube is ring-shaped; when using a standing wave thermoacoustic engine, the resonant tube is straight.

[0040] Figure 2 This schematically illustrates a typical standing-wave thermoacoustic engine, such as... Figure 2 As shown, the thermoacoustic engine 3 includes a resonant tube 311 and a cold-end heat exchanger 312, a first regenerator 313, and a hot-end heat exchanger 314 connected sequentially towards the resonant tube 311. One end of the cold-end heat exchanger 312 is connected to the outlet end of the liquid hydrogen pump, and the other end is connected to a gaseous hydrogen buffer tank. The hot-end heat exchanger 314 is placed in a room temperature environment, and its sidewall is connected to the resonant tube 311. The resonant tube 311 is connected to the cylinder of a pulse tube refrigerator, so that the oscillations generated by the thermoacoustic engine 3 are transmitted to the cylinder of the refrigerator via the resonant tube 311.

[0041] Thermoacoustic engines can also be traveling wave type thermoacoustic engines, such as... Figure 3 As shown, the thermoacoustic engine in Figure 2 Based on this, a thermal buffer tube 325 and a secondary hot-end heat exchanger 326 are added. The first cold-section heat exchanger 322, distinct from the first regenerator 323, is connected to the thermal buffer tube 325 on one side, and also connected to the secondary hot-end heat exchanger 326 via the thermal buffer tube 325. The other side of the secondary hot-end heat exchanger 326 is connected to the hot-end heat exchanger 324 and the pulse tube refrigerator via an annular resonant tube 321. In addition, the thermoacoustic engine can also employ a combination of standing waves and traveling waves, which will not be elaborated upon here.

[0042] In one specific embodiment of the invention, the cold-end heat exchanger of the thermoacoustic engine is connected to the outlet end of the liquid hydrogen pump, while the hot-end heat exchanger is placed in the environment and can output approximately 3 MJ / kgH2. A cryogenic fluid is introduced into the cold-end heat exchanger, utilizing its total latent heat (sensible and latent heat) to provide cooling. Under the temperature gradient between the hot and cold-end heat exchangers, the gas medium in the first regenerator oscillates along the thermoacoustic plates in the first regenerator. The resulting oscillations are transmitted to the working gas in the refrigerator cylinder via a resonant tube. The resonant tube is directly connected to the refrigerator cylinder to transfer the acoustic power generated by the thermoacoustic engine to the working gas, achieving cooling through the reciprocating oscillation of the working gas in the refrigerator cylinder.

[0043] like Figure 4 As shown, the pulse tube refrigerator 6 has a cold head 61, a pulse tube 62, and a room temperature heat exchanger 63 sequentially installed in its refrigerator cylinder. A second regenerator 64 is fitted onto the outer wall of the pulse tube 62. The inner top surface of the cold head 61 is tightly connected to the pulse tube 62. The end of the cold head 61 is connected to the output end of the room temperature heat exchanger 63 through the second regenerator 64.

[0044] The input end of the room temperature heat exchanger 63 is connected to a phase adjustment structure, which includes compressor pistons 66 symmetrically arranged in the compressor housing of the pulse tube refrigerator. The cavities between the compressor pistons 66 are interconnected to form a compression cavity 65.

[0045] The compression chamber 65 is equipped with symmetrically arranged non-area-difference dischargers 67 and a support leaf spring 68 fixedly connected to the non-area-difference dischargers 67. One end of the support leaf spring 68 abuts against the top surface of the compression chamber 65, and the other end abuts against the bottom surface of the compression chamber 65. A gap seal is formed between the non-area-difference dischargers 67 and the top and bottom surfaces of the compression chamber 65 to isolate fluid flow on both sides of the compressor piston 66. The non-area-difference dischargers 67 have identical and symmetrical cross-sections, dividing the compression chamber 65 into two compression chambers. An expansion chamber 69 is formed between the two symmetrically arranged non-area-difference dischargers 67. The non-area-difference dischargers 67 can reciprocate under the drive of pressure fluctuations, and a channel connecting to the room temperature heat exchanger 63 is formed between them and the compressor piston 66 and the housing. The non-area-difference dischargers 67 generate pressure fluctuations at the hot end of the pulse tube 62. The acoustic power generated by these pressure fluctuations is transferred to the compression chamber 65 for recovery by the room temperature heat exchanger 63.

[0046] The pulse tube can reduce heat exchange between the cold head and room temperature and transfer acoustic power. Specifically, a pulse tube heat exchanger is also provided at the end of the pulse tube 62 near the compression chamber 65.

[0047] The working gas in the compressor cylinder of the refrigeration unit undergoes reciprocating oscillation within the cold head 61, the second regenerator 64, the room temperature heat exchanger 63, and the pulse tube 62. When the working gas oscillates back and forth, it pumps the heat from the room temperature heat exchanger 63 to the cold head, and then discharges it out of the system through the room temperature heat exchanger, ultimately achieving refrigeration.

[0048] Specifically, the compressor pistons 66 are symmetrically arranged, with opposite directions of motion and their vibrations canceling each other out. The acoustic power generated by the thermoacoustic engine is transferred to the gas in the compression chamber and drives the compressor piston to reciprocate, thereby generating periodic pressure waves. The working gas (usually helium) in the expansion chamber expands and generates a cooling effect in the second regenerator, while simultaneously transferring the heat from the cold head to the room temperature heat exchanger, thus generating cooling in the cold head.

[0049] Preferably, the thermoacoustic engine and the pulse tube refrigerator have the same frequency after appropriate frequency matching to enhance the oscillation of the working gas in the refrigerator cylinder.

[0050] In one specific embodiment of the present invention, the no-load cooling temperature of the pulse tube refrigerator is 5-10K, and the operating temperature range of the thermoacoustic engine is 20-300K.

[0051] In a preferred embodiment of the present invention, in order to effectively utilize the cold energy recovered by the thermoacoustic engine, the cold head is placed in the liquid hydrogen storage tank; or a section of the cold head is connected to a cold finger, which is placed in the liquid hydrogen storage tank.

[0052] In one specific embodiment of the invention, the cooling energy in the cold head is transferred to the cold fingers, which in turn cool the hydrogen evaporating in the liquid hydrogen storage tank. Alternatively, the cold head can be placed directly in the liquid hydrogen storage tank to convert the evaporated hydrogen into liquid hydrogen.

[0053] The cold finger or cold head placed in the liquid hydrogen storage tank can further cool the evaporated hydrogen in the liquid hydrogen storage tank, turning it into liquid hydrogen. This not only saves the energy consumed in liquefying gaseous hydrogen, but also allows the energy generated by recovering the cooling capacity to be used in the liquid hydrogen refueling system, reducing the energy consumption of the entire industrial chain and thus reducing the cost of liquid hydrogen refueling stations.

[0054] For example, from an economic perspective, the energy consumption for hydrogen liquefaction is 14 kWh / kg. By adopting the cold energy recovery system of this invention, which utilizes a pulse tube refrigeration mechanism for cooling and liquefying gaseous hydrogen, a 4000 kg / d liquid hydrogen refueling station can increase its revenue by 2000 yuan / day. Liquid hydrogen storage tanks experience a certain degree of hydrogen evaporation and leakage. Using the recovered cold energy for gaseous hydrogen liquefaction reduces hydrogen evaporation and leakage, effectively utilizes the recovered cold energy, and significantly lowers the cost of the industrial chain.

[0055] Based on the cold energy recovery system for the liquid hydrogen refueling station proposed in this embodiment, assuming that all equipment in the system is in a shut-down or stopped state, the specific implementation steps include the following:

[0056] When the shut-off valve is opened, the liquid hydrogen in the liquid hydrogen storage tank enters the cold energy recovery device via the liquid hydrogen pump. It flows through the cold end heat exchanger of the thermoacoustic engine to complete the vaporization of the liquid hydrogen. The cold energy is converted into acoustic energy by the gas medium in the thermoacoustic engine and transferred to the working gas in the pulse tube refrigerator for recovery and utilization. The vaporized liquid hydrogen enters the gaseous hydrogen buffer tank through the conduit and is used for high-pressure hydrogen refueling of the hydrogen dispenser.

[0057] The present invention also provides a control method for a liquid hydrogen refueling station with a cold energy recovery system, the control method comprising:

[0058] Detect the pressure of the gaseous hydrogen buffer tank;

[0059] When the pressure in the gaseous hydrogen buffer tank is greater than the preset pressure, the cold energy recovery device and the liquid hydrogen pump are turned on in sequence.

[0060] Controlling the thermoacoustic engine to recover cold energy and drive the pulse tube refrigerator; and

[0061] When the pressure of the gaseous hydrogen buffer tank is less than or equal to the preset pressure, the liquid hydrogen pump is controlled to deliver hydrogen to the gaseous hydrogen buffer tank.

[0062] When the hydrogen dispenser receives a refueling request, it detects the hydrogen concentration of the hydrogen dispenser and the pressure of the liquid hydrogen storage tank; when the hydrogen concentration of the hydrogen dispenser and the pressure of the liquid hydrogen storage tank meet preset conditions, it detects the pressure of the gaseous hydrogen buffer tank.

[0063] Figure 5 This is a flowchart illustrating a control method for a liquid hydrogen refueling station according to an embodiment of the present invention. Figure 5 As shown, this method uses a liquid hydrogen storage tank, a liquid hydrogen pump, a cold energy recovery device (including a thermoacoustic engine and a pulse tube refrigerator), a gaseous hydrogen buffer tube, and a hydrogen dispenser. The method includes:

[0064] Step 11: Detect the hydrogen concentration in the hydrogen dispenser and the pressure in the liquid hydrogen storage tank;

[0065] Step 12: Check the pressure of the gaseous hydrogen buffer tank;

[0066] Step 13: Determine whether the pressure of the gaseous hydrogen buffer tank is equal to the preset pressure;

[0067] Step 14: When the pressure of the gaseous hydrogen buffer tank is greater than the preset pressure, the cold energy recovery device and the liquid hydrogen pump are turned on in sequence; the thermoacoustic engine is controlled to recover cold energy and drive the pulse tube refrigerator to work.

[0068] Step 15: When the pressure of the gaseous hydrogen buffer tank is less than or equal to the preset pressure, start the liquid hydrogen pump and control the liquid hydrogen pump to deliver hydrogen to the gaseous hydrogen buffer tank.

[0069] Step 16: Start the hydrogen refueling system.

[0070] The liquid hydrogen refueling station of the present invention has the above-mentioned cold energy recovery system. When the hydrogen dispenser receives a refueling signal, it needs to first check whether the hydrogen concentration of the hydrogen dispenser and the pressure of the liquid hydrogen storage tank meet the hydrogen refueling requirements. If the requirements are met, the pressure of the gaseous hydrogen buffer tank is checked. If the pressure of the gaseous hydrogen buffer tank is higher than 35 MPa, the cold energy recovery device and the liquid hydrogen pump can be started in sequence. The liquid hydrogen absorbs heat through the cold energy recovery device and is then input into the gaseous hydrogen buffer tank. At the same time as the hydrogen dispenser refuels, the thermoacoustic engine and the pulse tube refrigerator recover and utilize the cold energy lost by the liquid hydrogen. If the pressure of the gaseous hydrogen buffer tank is less than or equal to 35 MPa, the liquid hydrogen pump can be started first to meet the refueling requirements of the hydrogen dispenser.

[0071] The liquid hydrogen pump operates at a mass flow rate of 5-20 kg / min; the hydrogen dispenser operates at a dispensing rate of 3-20 kg / min.

[0072] The cold energy recovery system of the present invention operates on the basis of normal use of the hydrogen refueling machine. When the hydrogen refueling machine is in continuous use, the liquid hydrogen pump continuously delivers liquid hydrogen from the liquid hydrogen storage tank to the thermoacoustic engine, thereby enabling the thermoacoustic engine to recover and utilize the cold energy of the liquid hydrogen flowing through the cold end heat exchanger.

[0073] Taking a liquid hydrogen refueling station equipped with a 35MPa liquid hydrogen refueling unit as an example, the main parameters of this liquid hydrogen refueling unit are as follows:

[0074] The filling flow rate is 8-20 kg / min, the rated working pressure is 35 MPa, the maximum working pressure is 43.8 MPa, the maximum design pressure is 48.7 MPa, the filling pressure is 0.5-20 MPa, and the filling temperature is -40℃ to 50℃.

[0075] The overall process of this solution is as follows: When the hydrogen dispenser receives a hydrogen refueling signal, it first checks whether the hydrogen concentration in the dispenser and the pressure in the liquid hydrogen storage tank meet the hydrogen refueling requirements. If the hydrogen refueling requirements are met, the pressure of the gaseous hydrogen buffer tank is checked. If the pressure of the gaseous hydrogen buffer tank is higher than 35 MPa, the cold energy recovery device and the liquid hydrogen pump are started in sequence. The liquid hydrogen pump is turned on to pressurize the liquid hydrogen in the liquid hydrogen storage tank to about 2 MPa and then deliver it to the cold end heat exchanger of the thermoacoustic engine to exchange heat with the cryogenic liquid hydrogen and recover the cold energy in the cryogenic liquid hydrogen. The liquid hydrogen flows through the cold end heat exchanger at a refueling rate of 8-20 kg / min. After heat exchange, the liquid hydrogen vaporizes and rises to about -40°C, then enters the gaseous hydrogen buffer tank, and is then delivered to the hydrogen dispenser for external refueling.

[0076] The gas medium entering the cold-end heat exchanger is controlled at approximately -250℃, and exiting the cold-end heat exchanger at approximately -40℃. The gas medium in the first regenerator oscillates along the thermoacoustic plates within the first regenerator, and the resulting oscillations are transmitted to the working gas in the refrigerator cylinder via a resonant tube. The working gas oscillates reciprocally within the refrigerator cylinder to achieve refrigeration in the pulse tube refrigerator. The no-load refrigeration temperature of the pulse tube refrigerator is 10K.

[0077] In the cold energy recovery system provided in this embodiment, the second cold-end heat exchanger of the pulse tube refrigerator is placed in the liquid hydrogen storage tank, which can be used to liquefy the vaporized hydrogen in the liquid hydrogen storage tank. It should be noted that placing the cold head of the pulse tube refrigerator or the cold finger connected to the cold head in the liquid hydrogen can maintain the liquid hydrogen temperature or re-condense the BOG to reduce hydrogen evaporation loss. If the pressure of the gaseous hydrogen buffer tank is less than 35 MPa, only the liquid hydrogen pump is turned on to pressurize the liquid hydrogen in the liquid hydrogen storage tank to about 2 MPa before it flows through the cold-end heat exchanger to exchange heat with the cryogenic liquid hydrogen. The rate at which liquid hydrogen passes through the cold-end heat exchanger is 8-20 kg / min.

[0078] For a liquid hydrogen refueling station with a hydrogen refueling rate of 14 kg / min, if the hydrogen refueling volume is calculated at 1000 kg / 12hr per day, the electricity consumption saved by the system based on the present invention for hydrogen volatilization in the liquefied liquid hydrogen storage tank is equivalent to 2000 kWh / d.

[0079] Statistics show that within one month of operating the above system, the hydrogen quality loss rate of liquid hydrogen refueling stations decreased by approximately 20% to 50%, which greatly reduced hydrogen consumption and improved the economic efficiency of hydrogen refueling station operations.

[0080] This invention also provides a method for recovering and utilizing the cold energy of a liquid hydrogen refueling station, the method specifically including the following steps:

[0081] When the hydrogen dispenser receives a hydrogen refueling signal, it first checks whether the hydrogen concentration in the dispenser and the pressure in the liquid hydrogen storage tank meet the refueling requirements. If the refueling requirements are met, it checks the pressure in the gaseous hydrogen buffer tank. If the pressure in the gaseous hydrogen buffer tank is higher than 35 MPa, it sequentially starts the cold energy recovery device and the liquid hydrogen pump. The liquid hydrogen pump is turned on, pressurizing the liquid hydrogen in the storage tank to 35 MPa before delivering it to the cold-end heat exchanger of the thermoacoustic engine to exchange heat with the cryogenic liquid hydrogen and recover its cold energy. The liquid hydrogen flows through the cold-end heat exchanger at a rate of 8-20 kg / min. After heat exchange, the liquid hydrogen vaporizes and heats up to approximately -20°C, then enters the gaseous hydrogen buffer tank, and is subsequently delivered to the hydrogen dispenser for external refueling.

[0082] If the pressure in the gaseous hydrogen buffer tank is less than 35 MPa, only the liquid hydrogen pump is turned on to pressurize the liquid hydrogen in the liquid hydrogen storage tank to 35 MPa before it flows through the cold-end heat exchanger to exchange heat with the cryogenic liquid hydrogen. The rate at which liquid hydrogen passes through the cold-end heat exchanger is 8-20 kg / min.

[0083] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0084] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0085] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A cold energy recovery system, comprising a liquid hydrogen pump and a gaseous hydrogen buffer tank, characterized in that, A cold energy recovery device is provided between the liquid hydrogen pump and the gaseous hydrogen buffer tank. The cold energy recovery device includes at least one stage thermoacoustic engine and at least one stage pulse tube refrigerator. The thermoacoustic engine can recover the cold energy released by the liquid hydrogen flowing through the thermoacoustic engine and drive the pulse tube refrigerator to perform refrigeration. The thermoacoustic engine includes a resonant tube and a cold-end heat exchanger, a first regenerator, and a hot-end heat exchanger connected in sequence toward the resonant tube. The resonant tube is connected to the cylinder of the pulse tube refrigerator so that the oscillation generated by the thermoacoustic engine is transmitted to the cylinder of the refrigerator through the resonant tube; One end of the cold-end heat exchanger is connected to the outlet end of the liquid hydrogen pump, and the other end is connected to the gaseous hydrogen buffer tank. The refrigeration unit cylinder is sequentially equipped with a cold head, a pulse tube, and a room temperature heat exchanger. A second regenerator is fitted on the outer wall of the pulse tube. The end of the cold head is connected to the output end of the room temperature heat exchanger through the second regenerator. The pulse tube is connected to a phase-adjusting structure, which includes compressor pistons symmetrically arranged in the housing of the refrigeration unit. The compressor pistons are interconnected to form a compression chamber. The compression chamber is symmetrically arranged with a discharge device without area difference and a support leaf spring fixedly connected to the discharge device without area difference. The discharge devices without area difference form an expansion chamber, and the discharge devices without area difference can reciprocate under the action of acoustic power transmitted to the refrigeration unit through the resonant tube. The cold energy recovery system also includes a liquid hydrogen storage tank, in which the cold head is placed; or the cold end of the cold head is connected to a cold finger, which is placed in the liquid hydrogen storage tank.

2. The cold energy recovery system according to claim 1, wherein, The thermoacoustic engine is one of the following: a standing wave thermoacoustic engine, a traveling wave thermoacoustic engine, and a standing wave-traveling wave hybrid thermoacoustic engine. The operating temperature range of the thermoacoustic engine is 20-300K; The thermoacoustic engine outputs 3-3.5 MJ / kgH2.

3. The cold energy recovery system according to claim 1, wherein, The pulse tube refrigerator is a single-stage pulse tube refrigerator or a multi-stage pulse tube refrigerator. The no-load cooling temperature of the pulse tube refrigerator is 5-10K.

4. A control method for a liquid hydrogen refueling station having the cold energy recovery system according to any one of claims 1-3, characterized in that, The control method includes: Detect the pressure of the gaseous hydrogen buffer tank; When the pressure in the gaseous hydrogen buffer tank exceeds the preset pressure, the cold energy recovery device and the liquid hydrogen pump are activated sequentially; the thermoacoustic engine is controlled to recover cold energy and drive the pulse tube refrigerator to operate; and... When the pressure of the gaseous hydrogen buffer tank is less than or equal to the preset pressure, the liquid hydrogen pump is controlled to deliver hydrogen to the gaseous hydrogen buffer tank.

5. The control method according to claim 4, wherein, When the hydrogen dispenser receives a refueling request, it detects the hydrogen concentration in the hydrogen dispenser and the pressure in the liquid hydrogen storage tank. When the hydrogen concentration of the hydrogen dispenser and the pressure of the liquid hydrogen storage tank meet the preset conditions, the pressure of the gaseous hydrogen buffer tank is detected.

6. The control method according to claim 5, wherein, The mass flow rate of the liquid hydrogen pump during operation is 5-20 kg / min; The hydrogenation rate of the hydrogenation machine is 3-20 kg / min.

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