Metal hydride compression system and method

Abstract

The application discloses a metal hydride compression system, comprising a reverse Carnot cycle unit and a metal hydride compression tank group, the reverse Carnot cycle unit has a refrigerant circuit for circulating flow of refrigerant working medium, the metal hydride compression tank group comprises at least two compression tanks, each of the compression tanks is provided with an internal heat exchanger, the internal heat exchanger is connected in series in the refrigerant circuit, and the refrigerant working medium is directly heat-exchanged with hydrogen storage material in the tank when flowing through the internal heat exchanger; three three-way switching valves and throttling elements are arranged on the refrigerant circuit, and the refrigerant circuit is switched between the following two communication states through switching of the three three-way switching valves and alternate conduction of the throttling elements. A metal hydride compression method is also provided. The application has the technical advantages of greatly improving system compression efficiency, reducing energy consumption and improving integration.

Description

Technical Field

[0001] This invention relates to the field of hydrogen compression and preparation equipment technology, specifically to a metal hydride compression system and method, applicable to hydrogen pressurization processes in scenarios such as hydrogen storage, transportation, and hydrogen refueling stations. Background Technology

[0002] Hydrogen energy, as a clean, efficient, and sustainable secondary energy source, has significant application prospects in energy storage, transportation, industry, and distributed energy supply. The compression, storage, and transportation of hydrogen are crucial steps in the large-scale application of hydrogen energy. Currently, hydrogen is typically produced using methods such as steam reforming, water electrolysis, coal gasification, biomass gasification, and fossil fuel reforming. Hydrogen needs to be compressed to high pressures before use; for example, fuel cell vehicles typically require storing hydrogen in high-pressure tanks at 350 bar or 700 bar. Therefore, efficient, safe, and low-cost hydrogen compression technology is a key support for realizing a hydrogen economy.

[0003] Currently, the most commonly used hydrogen compression methods in industry are mechanical compression, including reciprocating compressors, diaphragm compressors, and centrifugal compressors. These mechanical compressors rely on volume changes to pressurize the gas, and generally suffer from problems such as high wear of moving parts, high sealing requirements, easy leakage, high vibration and noise, and high maintenance costs. Under high-pressure hydrogen conditions, they also have shortcomings such as oil contamination, high safety risks, and limited lifespan, making it difficult to meet the long-term, stable, oil-free high-purity hydrogen compression requirements.

[0004] To overcome the inherent limitations of mechanical compressors, hydrogen compression technology based on the thermal effect of metal hydrides has gradually attracted attention. Metal hydrides reversibly absorb and release hydrogen under certain temperatures and pressures, accompanied by a significant thermal effect: heat is released during hydrogen absorption and absorbed during hydrogen release. By cooling and heating the metal hydrides, hydrogen can be absorbed at low temperatures and low pressures and released at high temperatures and high pressures, thus achieving thermochemical hydrogen compression that is characterized by no mechanical movement, no oil, quiet operation, and high safety. These systems are primarily driven by thermal energy rather than electrical energy.

[0005] However, existing conventional metal hydride compression systems still have the following significant drawbacks: 1. High system energy consumption.

[0006] Existing technologies typically employ separate heat and cold sources for heating and cooling, such as electric heating rods, cooling water, and air cooling, resulting in low energy utilization efficiency and high system energy consumption. While some solutions attempt to provide a combined heat and cold source using heat pump technology, the overall energy efficiency remains unsatisfactory.

[0007] Second, the system has low compression efficiency and slow thermal response due to multiple heat exchange processes.

[0008] In existing technologies, metal hydride compression systems using heat pump technology provide a connection between the heat source and the cold source. The high-temperature hydrogen release and heat absorption process involves heat exchange between a refrigerant (such as Freon) in an external condenser and a heat transfer fluid (such as water or oil). This heat transfer fluid then exchanges heat with the hydrogen storage material, heating the material and releasing high-pressure hydrogen. The low-temperature hydrogen absorption and heat release process involves heat exchange between a refrigerant in an external evaporator and a heat transfer fluid. This heat transfer fluid then exchanges heat with the hydrogen storage material, cooling the material and allowing it to absorb low-pressure hydrogen.

[0009] This design suffers from a fundamental thermodynamic flaw: the heat or cold energy of the refrigerant must pass through multiple transfer paths—"refrigerant → heat transfer fluid → hydrogen storage material"—resulting in heat loss at each heat exchange stage. Furthermore, the heat capacity and flow resistance of the heat transfer fluid further reduce the thermal response speed. Because both processes involve multiple heat exchanges, the slow thermal response of the hydrogen storage material leads to a slow hydrogen absorption and desorption rate, resulting in low compression efficiency and high energy consumption for the metal hydride.

[0010] Literature reports indicate that a single-stage compression scheme integrating a heat pump and a series-connected metal hydride tank achieves a compression ratio of only 2.0, a tank operating temperature range of 12 to 55°C, an average heating power of only 362 W, ​​and a cooling power of only 300 W. The productivity of the metal hydride compressor depends primarily on the achievable heat transfer rate, which is limited by the pressure-bearing walls separating the heat transfer fluid from the metal hydride reaction bed and their effective thermal conductivity.

[0011] Third, the system has low integration, complex piping, and large size.

[0012] In existing technologies, whether metal hydride compression systems use independent heat and cold sources or coupled heat pump technology to provide related heat and cold sources, the condenser and evaporator are external heat exchangers that do not directly contact the hydrogen storage material. This requires the installation of multiple fluid circulation pipelines, resulting in complex system piping and making it difficult to achieve small-scale system integration.

[0013] For example, a hydrogen compression system is disclosed in the prior art. This system includes a heat pump section (with a heat pump pipeline for refrigerant circulation), a hydrogen compression section (compressing hydrogen through repeated heating and cooling), a first circulation pipeline (connected to the heat pump pipeline and circulating refrigerant through the hydrogen compression section), a second circulation pipeline (passing through the hydrogen compression section and circulating cooling fluid), and a cooling unit (located in the second circulation pipeline for cooling the cooling fluid). In this scheme, the hydrogen compression section is heated by refrigerant or cooled by cooling fluid, the heat pump section provides the heat source, and the cooling unit provides the cold source. Because the heat and cold sources are independent of each other, to achieve heat and cold alternation, the system has two main circulation loops and four bypass branches, with heat and cold alternation achieved by the operation of four three-way switching valves. This makes the system piping extremely complex, and the condenser and evaporator of the heat pump section are external heat exchangers, not in direct contact with the hydrogen storage material, making it difficult to achieve small-scale system integration.

[0014] Furthermore, a prototype of a series-connected metal hydride compressor using a heat pump as a heat source and cold source is disclosed in the prior art. This scheme includes a pair of metal hydride tanks arranged in series, equipped with an integrated heat exchanger, with the tanks being alternately heated and cooled. However, it also uses an external condenser and evaporator to indirectly exchange heat with the hydrogen storage material through a heat transfer fluid, and only achieves single-stage compression with a compression ratio of only 2.0.

[0015] In summary, existing metal hydride compression technologies generally suffer from the following common defects: First, the heat transfer path is long, and the multiple heat exchange processes from refrigerant to heat transfer fluid to hydrogen storage material result in slow thermal response and low energy efficiency; second, the switching of cold and heat sources requires multiple complex circulation loops and multiple switching valves, leading to complex system structure and low integration; third, the number of compression stages is fixed, resulting in poor adaptability and low compression ratio, making it difficult to meet the high-efficiency compression requirements under different inlet pressure scenarios. Summary of the Invention

[0016] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a metal hydride compression system and method with high compression efficiency, low energy consumption and high integration. By directly integrating the condenser and evaporator functions of the reverse Carnot cycle unit into the compression tank, the refrigerant and hydrogen storage material can be directly exchanged for heat, eliminating multiple heat exchange links. The complete switching of the hot and cold circuits is achieved with only three three-way switching valves, thereby significantly improving the system compression efficiency, reducing energy consumption and increasing integration.

[0017] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A metal hydride compression system includes a reverse Carnot cycle unit and a metal hydride compression tank assembly. The reverse Carnot cycle unit has a refrigerant circuit for circulating refrigerant. The metal hydride compression tank assembly includes at least two compression tanks, each of which is equipped with an internal heat exchanger connected in series in the refrigerant circuit. The refrigerant directly exchanges heat with the hydrogen storage material inside the tank as it flows through the internal heat exchanger. The refrigerant circuit is equipped with three three-way switching valves and a throttling element, used to switch the refrigerant circuit between two connection states through the switching of the three three-way switching valves and the alternating conduction of the throttling element: In the first state, the refrigerant in the refrigerant circuit flows sequentially through the internal heat exchanger of the first compression tank, the throttling element, and the internal heat exchanger of the second compression tank. The high-temperature and high-pressure refrigerant flowing through the internal heat exchanger of the first compression tank releases heat to the hydrogen storage material, causing it to heat up and release hydrogen. The low-temperature refrigerant, after being throttled and cooled by the throttling element, absorbs heat from the hydrogen storage material when it flows through the internal heat exchanger of the second compression tank, causing it to cool down and absorb hydrogen. In the second state, the refrigerant in the refrigerant circuit flows sequentially through the internal heat exchanger of the second part of the compression tank, the throttling element, and the internal heat exchanger of the first part of the compression tank. The high-temperature and high-pressure refrigerant flowing through the internal heat exchanger of the second part of the compression tank releases heat to the hydrogen storage material, causing it to heat up and release hydrogen. The low-temperature refrigerant, after being throttled and cooled by the throttling element, absorbs heat from the hydrogen storage material when it flows through the internal heat exchanger of the first part of the compression tank, causing it to cool down and absorb hydrogen.

[0018] As a further improvement to the above technical solution: The three three-way switching valves are an intake three-way switching valve, an exhaust three-way switching valve, and a temperature control three-way switching valve; the throttling element includes a first electronic expansion valve and a second electronic expansion valve disposed on the refrigerant circuit. The first electronic expansion valve and the second electronic expansion valve are respectively disposed on two parallel branches between the first partial compression tank and the second partial compression tank, and are respectively connected in series in the two parallel branches. In the first state, the second electronic expansion valve is open and the first electronic expansion valve is closed. In the second state, the first electronic expansion valve is open and the second electronic expansion valve is closed.

[0019] The reverse Carnot cycle unit also includes a water circulation loop, which includes an air-cooled heat exchanger and a water pump. The water circulation loop and the refrigerant loop exchange heat through the heat exchanger.

[0020] It includes a first compression tank and a second compression tank. The first compression tank contains low-pressure hydrogen storage material, and the second compression tank contains high-pressure hydrogen storage material. In the first state, the refrigerant flows sequentially through the second compression tank, the throttling element, and the first compression tank. The second compression tank releases hydrogen to the high-pressure hydrogen storage cylinder group, and the first compression tank draws hydrogen from the low-pressure hydrogen source. In the second state, the refrigerant flows sequentially through the first compression tank, the throttling element, and the second compression tank. The first compression tank releases hydrogen to the second compression tank, and the second compression tank draws hydrogen from the first compression tank.

[0021] It includes a third compression tank and a fourth compression tank, both containing hydrogen storage materials with the same pressure platform. In the first state, the refrigerant flows sequentially through the fourth compression tank, the throttling element, and the third compression tank, with the fourth compression tank releasing hydrogen to a high-pressure hydrogen storage cylinder group and the third compression tank drawing hydrogen from a low-pressure hydrogen source. In the second state, the refrigerant flows sequentially through the third compression tank, the throttling element, and the fourth compression tank, with the third compression tank releasing hydrogen to a high-pressure hydrogen storage cylinder group and the fourth compression tank drawing hydrogen from a low-pressure hydrogen source.

[0022] The system includes a fifth, sixth, seventh, and eighth compression tank. The fifth and seventh compression tanks contain low-pressure hydrogen storage materials, while the sixth and eighth compression tanks contain high-pressure hydrogen storage materials. In the first state, the seventh compression tank releases hydrogen to the sixth compression tank, and the eighth compression tank releases hydrogen to the high-pressure hydrogen storage cylinder group. The fifth compression tank draws hydrogen from a low-pressure hydrogen source, and the sixth compression tank draws hydrogen from the seventh compression tank. The refrigerant flows sequentially through the seventh compression tank, the eighth compression tank, a throttling element, the sixth compression tank, and the fifth compression tank. In the second state, the fifth compression tank releases hydrogen to the eighth compression tank, and the sixth compression tank releases hydrogen to the high-pressure hydrogen storage cylinder group. The seventh compression tank draws hydrogen from a low-pressure hydrogen source, and the eighth compression tank draws hydrogen from the fifth compression tank. The refrigerant flows sequentially through the fifth compression tank, the sixth compression tank, a throttling element, the eighth compression tank, and the seventh compression tank.

[0023] The system includes a ninth, tenth, and eleventh compression tank. The ninth compression tank contains low-pressure hydrogen storage material, the eleventh compression tank contains medium-pressure hydrogen storage material, and the tenth compression tank contains high-pressure hydrogen storage material. In the first state, hydrogen is released from the ninth compression tank to the eleventh compression tank, and hydrogen is released from the tenth compression tank to the high-pressure hydrogen storage cylinder group. The eleventh compression tank draws hydrogen from the ninth compression tank, and the refrigerant flows sequentially through the ninth compression tank, the tenth compression tank, the throttling element, and the eleventh compression tank. In the second state, hydrogen is released from the eleventh compression tank to the tenth compression tank, hydrogen is drawn from the ninth compression tank from a low-pressure hydrogen source, and hydrogen is drawn from the eleventh compression tank by the tenth compression tank. The refrigerant flows sequentially through the eleventh compression tank, the throttling element, the tenth compression tank, and the ninth compression tank.

[0024] It includes a twelfth, thirteenth, fourteenth, and fifteenth compression tanks. The twelfth compression tank contains low-pressure hydrogen storage material, the fourteenth and thirteenth compression tanks contain medium-pressure hydrogen storage material, and the fifteenth compression tank contains high-pressure hydrogen storage material. In the first state, the fourteenth compression tank releases hydrogen to the thirteenth compression tank, and the fifteenth compression tank releases hydrogen to the high-pressure hydrogen storage cylinder group. The twelfth compression tank draws hydrogen from a low-pressure hydrogen source, and the thirteenth compression tank draws hydrogen from the fourteenth compression tank. The refrigerant... The refrigerant flows sequentially through the fourteenth compression tank, the fifteenth compression tank, the throttling element, the thirteenth compression tank, and the twelfth compression tank. In the second state, hydrogen is released from the twelfth compression tank to the fourteenth compression tank, and hydrogen is released from the thirteenth compression tank to the fifteenth compression tank. The fourteenth compression tank draws hydrogen from the twelfth compression tank, and the fifteenth compression tank draws hydrogen from the thirteenth compression tank.

[0025] Each of the compression tanks is equipped with a mechanical check valve on its hydrogen outlet pipeline, which is used to automatically open or close based on the pressure difference between the two ends; the high-pressure hydrogen storage cylinder group is connected to a safety unloading valve, which automatically opens to release pressure when the pressure of the high-pressure hydrogen storage cylinder group exceeds a set threshold.

[0026] A metal hydride compression method employs a metal hydride compression system as described in any of the preceding claims, comprising an alternating first stage and a second stage: First stage: Switching the refrigerant circuit, causing the refrigerant working fluid to flow sequentially through the refrigerant compressor outlet, the internal heat exchanger of a first partial compression tank, a throttling element, the internal heat exchanger of a second partial compression tank, and the refrigerant compressor inlet; the first partial compression tank is heated to release hydrogen, and the second partial compression tank is cooled to draw in hydrogen; Second stage: Switching the refrigerant circuit, causing the refrigerant working fluid to flow sequentially through the refrigerant compressor outlet, the internal heat exchanger of the second partial compression tank, a throttling element, the internal heat exchanger of the first partial compression tank, and the refrigerant compressor inlet; the second partial compression tank is heated to release hydrogen, and the first partial compression tank is cooled to draw in hydrogen; Repeating the first stage and the second stage achieves continuous compression of hydrogen.

[0027] Compared with the prior art, the advantages of the present invention are as follows: First, this invention eliminates multiple heat exchange stages, significantly improving thermal response speed and energy utilization efficiency.

[0028] In the existing technology, the condenser and evaporator of the heat pump are both external. The refrigerant needs to exchange heat with the heat transfer fluid (water, oil, etc.) first, and the heat transfer fluid is then circulated back to the compression tank to exchange heat with the hydrogen storage material. This multiple heat exchange path of "refrigerant → heat transfer fluid → hydrogen storage material" has the following problems: (1) heat loss occurs every time heat exchange occurs; (2) the heat capacity of the heat transfer fluid increases the thermal inertia of the system, resulting in a lag in temperature change; (3) the circulation of the heat transfer fluid requires additional pump power consumption; (4) the heat exchange between the heat transfer fluid and the hydrogen storage material is limited by the thermal conductivity of the pressure bearing wall.

[0029] This invention completely eliminates the intermediate heat transfer fluid step, directly introducing the refrigerant into the internal heat exchanger within the compression tank for direct heat exchange with the hydrogen storage material. The refrigerant undergoes a complete thermodynamic cycle in a reverse Carnot cycle, sequentially performing compression (heat and pressure increase), condensation and heat release (heat release to the hydrogen storage material within the hydrogen release tank), throttling and expansion (heat and pressure decrease), and evaporation and heat absorption (heat absorption from the hydrogen storage material within the hydrogen absorption tank). The high-temperature, high-pressure refrigerant directly releases heat to the hydrogen storage material within the hydrogen release tank (equivalent to a condenser function built into the tank), while the throttled, low-temperature refrigerant directly absorbs heat from the hydrogen storage material within the hydrogen absorption tank (equivalent to an evaporator function built into the tank). This design eliminates all intermediate heat exchange steps, significantly improving thermal response speed and energy utilization efficiency.

[0030] II. This invention achieves tiered utilization of cold and hot energy through a single-path series circulation.

[0031] In existing technologies, heating and cooling are accomplished through independent circuits, with each circuit operating independently. This invention employs a design where the refrigerant flows through two sets of compression tanks in a single, series-connected path: the high-temperature, high-pressure refrigerant first flows through the hydrogen release tank (releasing heat and cooling), then undergoes further cooling via an electronic expansion valve, and finally flows through the hydrogen absorption tank (absorbing heat and heating), before returning to the compressor inlet to complete the cycle. During this process, the low-grade heat released by the hydrogen absorption tank is converted into high-grade heat by the refrigerant compressor, which then supplies the hydrogen release tank with the released hydrogen. After further cooling via throttling, this heat is used to cool the hydrogen absorption tank, achieving the cascade utilization and recovery of thermal energy.

[0032] Third, the extremely simple valve control architecture of this invention achieves high integration.

[0033] Existing technologies require four three-way switching valves in conjunction with two main circulation loops and four bypass branches to complete the hot / cold switching; some solutions require eight switching valves. This invention requires only three three-way switching valves to complete all hot / cold switching functions—the combined switching of the intake three-way valve, exhaust three-way valve, and temperature control three-way valve allows the refrigerant circuit to switch between two states. Combined with the alternating opening and closing of two electronic expansion valves, this achieves complete reversal of the refrigerant flow between the two sets of compression tanks. This significant reduction in the number of valves directly brings multiple benefits, including simplified system piping, reduced size, simplified control logic, and improved reliability.

[0034] IV. The modular hierarchical compression architecture of this invention enables wide pressure range adaptation.

[0035] In existing technologies, the number of compression stages in metal hydride compression systems is usually fixed, making it difficult to adapt to different inlet pressure scenarios. This invention achieves modular expansion from single-stage to four-stage by customizing hydrogen storage alloys for different pressure platforms and flexibly configuring the number and number of compression tanks: a two-tank two-stage scheme (2MPa→35MPa), a two-tank single-stage scheme (9MPa→35MPa), a three-tank three-stage scheme (0.2MPa→35MPa), and a four-tank four-stage scheme (2MPa→70MPa). This allows for flexible adaptation to various hydrogen supply scenarios, from low-pressure by-product hydrogen to high-pressure industrial hydrogen. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the two-tank, two-stage metal hydride compression system in a specific application embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the two-tank single-stage metal hydride compression system in a specific application embodiment two of the present invention.

[0038] Figure 3 This is a schematic diagram of the four-tank two-stage metal hydride compression system in a specific application embodiment three of the present invention.

[0039] Figure 4 This is a schematic diagram of the three-tank, three-stage metal hydride compression system in a specific application embodiment four of the present invention.

[0040] Figure 5 This is a schematic diagram of the four-tank, four-stage metal hydride compression system in a specific application embodiment five of the present invention.

[0041] The labels in the diagram represent: 001. Refrigerant compressor; 002. Intake three-way switching valve; 003. Exhaust three-way switching valve; 004. Temperature control three-way switching valve; 005. First electronic expansion valve; 006. Second electronic expansion valve; 007. Heat exchanger; 008. Air-cooled heat exchanger; 009. Water pump; 10. High-pressure hydrogen storage tank assembly; 11. First compression tank; 12. Second compression tank; 21. Third compression tank; 22. Fourth compression tank; 31. Fifth compression tank; 32. Seventh compression tank; 33. Sixth compression tank; 34. Eighth compression tank; 41. Ninth compression tank; 42. Eleventh compression tank; 43. Tenth compression tank; 51. Twelfth compression tank; 52. Fourteenth compression tank; 53. Thirteenth compression tank; 54. Fifteenth compression tank. 101, Check valve; 102, Check valve; 103, Check valve; 201, Check valve; 202, Check valve; 203, Check valve; 204, Check valve; 301, Check valve; 302, Check valve; 303, Check valve; 304, Check valve; 305, Check valve; 306, Check valve; 401, Check valve; 402, Check valve; 403, Check valve; 404, Check valve; 501, Check valve; 502, Check valve; 503, Check valve; 504, Check valve; 505, Check valve. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0045] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0046] like Figures 1 to 5 As shown, this embodiment provides a metal hydride compression system, which mainly includes a reverse Carnot cycle unit and a metal hydride compression tank group. In this embodiment, for ease of explanation and understanding, a hydrogen delivery and storage unit is also included.

[0047] The reverse Carnot cycle unit consists of a refrigerant circulation loop and a water circulation loop. The refrigerant circulation loop is equipped with a refrigerant compressor 001, a suction three-way switching valve 002, a discharge three-way switching valve 003, a temperature control three-way switching valve 004, a first electronic expansion valve 005, a second electronic expansion valve 006, and a heat exchanger 007. The water circulation loop is equipped with an air-cooled heat exchanger 008 and a water pump 009. The water circulation loop and the refrigerant circulation loop exchange heat through the heat exchanger 007.

[0048] The three three-way switching valves 002, 003, and 004 are automatic valves of the same specification and model, each with three ports a, b, and c, and only two operating states. State one is a through c, b not through c, and a not through b; state two is b through c, a not through c, and a not through b. By combining and switching these three valves, the refrigerant circuit can switch between the two connected states, thereby realizing the alternating flow of refrigerant between the two sets of compression tanks.

[0049] The metal hydride compression tank assembly comprises at least two compression tanks. Each compression tank is equipped with a high-pressure resistant internal heat exchanger, which is connected in series in the refrigerant circuit. The refrigerant, as it flows through the internal heat exchanger, directly exchanges heat with the hydrogen storage material inside the tank. When the high-temperature, high-pressure refrigerant flows through, it releases heat to the hydrogen storage material, causing it to heat up and release hydrogen; when the refrigerant, after being throttled and cooled, flows through, it absorbs heat from the hydrogen storage material, causing it to cool down and absorb hydrogen.

[0050] The hydrogen delivery and storage unit includes mechanical check valves installed on the hydrogen outlet pipelines of each compression tank, a high-pressure hydrogen storage cylinder group 10, and a safety unloading valve. The check valves are mechanical check valves that automatically open or close based on the pressure difference between the two ends, requiring no electrical control signal. The high-pressure hydrogen storage cylinder group 10 is connected to a safety unloading valve, which automatically opens to release pressure when the pressure exceeds a set threshold.

[0051] The control unit controls the switching of the three three-way switching valves, the opening and closing of the electronic expansion valve, and the operating conditions of the refrigerant compressor. Specifically, the control unit switches the refrigerant circuit between the first and second states by controlling the switching of the suction three-way switching valve 002, the discharge three-way switching valve 003, and the temperature control three-way switching valve 004; at the same time, it controls the alternating opening and closing of the first electronic expansion valve 005 and the second electronic expansion valve 006, and adjusts the opening degree of each electronic expansion valve in real time according to the temperature and pressure of the hydrogen storage tank, thereby controlling the flow rate of the refrigerant and the evaporation / condensation temperature to ensure that the hydrogen absorption and desorption reactions take place under optimal operating conditions.

[0052] The working principle of this invention is based on the deep coupling of the reverse Carnot cycle and the thermal effect of metal hydrides, as detailed below: The refrigerant undergoes a complete thermodynamic cycle in the system: the refrigerant compressor 001 compresses the low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure superheated vapor (compression process); the high-temperature, high-pressure refrigerant enters the internal heat exchanger of the first-part compression tank (in the first state), releasing heat to the hydrogen storage material inside the tank, causing it to heat up and release hydrogen, while the refrigerant itself condenses into a liquid or gas-liquid two-phase state (equivalent to a condenser function built into the compression tank); the condensed refrigerant flows through the electronic expansion valve 005 or 006 for throttling and pressure reduction, and its temperature drops further rapidly (throttling process); the low-temperature, low-pressure refrigerant enters the internal heat exchanger of the second-part compression tank, absorbing heat from the hydrogen storage material inside the tank, causing it to cool down and absorb hydrogen, while the refrigerant itself evaporates into low-pressure vapor (equivalent to an evaporator function built into the compression tank); the low-pressure refrigerant vapor flows back to the refrigerant compressor inlet, completing a complete reverse Carnot cycle. It should be noted that in this application, "first-part compression tank" and "second-part compression tank" are two group codes, representing two groups of compression tanks participating in the alternating cycle, respectively. In the first state, the refrigerant flows from the first part to the second part; in the second state, the refrigerant flows in the reverse direction, from the second part to the first part. The same physical tank may be assigned different group codes in different states, that is, the order between the two groups is completely interchangeable as the state changes, which reflects the core working logic of "alternation" in this invention.

[0053] The key technology of the above-mentioned cycle lies in the fact that the refrigerant sequentially completes the dual functions of "releasing heat to the hydrogen storage material (heating and releasing hydrogen)" and "absorbing heat from the hydrogen storage material (cooling and absorbing hydrogen)" in a series loop. In traditional technology, these two functions are accomplished separately by an external condenser and an external evaporator mediated by a heat transfer fluid. This invention achieves the following three core innovations: First, it eliminates multiple heat exchange stages. In traditional heat pumps, both the condenser and evaporator are external, requiring the refrigerant to undergo at least two heat exchanges—"refrigerant → heat transfer fluid → hydrogen storage material"—to transfer heat / cold energy to the hydrogen storage material. Each heat exchange results in heat loss and increases thermal inertia. This invention directly introduces the refrigerant into an internal heat exchanger within the compression tank, directly exchanging heat with the hydrogen storage material. This achieves a "single heat exchange" from the refrigerant to the hydrogen storage material, completely eliminating the intermediate heat transfer fluid stage. This design significantly improves the thermal response speed. The heat generated by hydrogen absorption and release can be rapidly carried away by the refrigerant, and the heat required for hydrogen release and absorption can be quickly supplied by the refrigerant, thereby significantly accelerating the hydrogen absorption and release reaction rate and increasing the amount of hydrogen compressed per unit time.

[0054] Secondly, it achieves the cascaded utilization of thermal energy. After releasing heat in the hydrogen release tank, the high-temperature, high-pressure refrigerant's temperature remains higher than the temperature required for hydrogen absorption by the storage material. If it were directly returned to the compressor, this sensible heat would be wasted. This invention allows the refrigerant, after releasing heat and cooling, to flow through an electronic expansion valve for further cooling before entering the hydrogen absorption tank to absorb heat. This process ensures that the heat released by the refrigerant in the hydrogen release tank is carried to the hydrogen absorption tank side, where it is further cooled by throttling and then used to cool the hydrogen absorption tank. This achieves the cascaded utilization of the refrigerant's sensible heat and latent heat of phase change, significantly reducing system energy consumption.

[0055] Third, the valve control architecture is extremely simplified. This invention only requires three three-way switching valves and a throttling element to complete the switching of the hot and cold circuits. The suction three-way valve 002 switches the intake source of the refrigerant compressor, the discharge three-way valve 003 switches the discharge direction of the refrigerant compressor, and the temperature control three-way valve 004 switches the refrigerant flow direction. In contrast, traditional solutions require four three-way switching valves to cooperate with two main circulation circuits and four bypass branches, or up to eight switching valves. The significant reduction in the number of valves directly leads to simplified system piping, simplified control logic, and improved reliability.

[0056] Based on the above working principle and core innovation, this invention achieves the following beneficial effects: First, the compression efficiency of this invention is significantly improved. By eliminating multiple heat exchange stages, the heating / cooling rate of the hydrogen storage material is significantly accelerated, and the hydrogen absorption and desorption reactions can be completed in a shorter time. Compared with traditional solutions that use heat transfer fluid as a medium, the thermal response speed of this invention can be increased several times, the amount of hydrogen compressed per unit time is significantly increased, and the compression efficiency is greatly improved.

[0057] Secondly, the energy consumption of the system of the present invention is significantly reduced. On the one hand, after the refrigerant releases heat and cools down in the hydrogen release tank, it is further cooled down by throttling before entering the hydrogen absorption tank to absorb heat, realizing the cascade utilization of cold and hot energy and avoiding energy waste; on the other hand, the pump power consumption required for the circulation of heat transfer fluid is eliminated, reducing the system's auxiliary energy consumption.

[0058] Third, the system integration of this invention is greatly improved. The functions of the condenser and evaporator are built into the compression tank, eliminating the need for external condensers, evaporators and their associated heat transfer fluid pipelines; switching between hot and cold requires only 3 three-way switching valves and throttling elements, eliminating the need for 2 main circulation loops and 4 bypass branches; the entire system has symmetrically distributed pipelines, a compact structure, and a significantly reduced volume, facilitating modular integration.

[0059] Fourth, this invention has a wide range of applications. By flexibly configuring the number of compression tanks and the pressure platform of the hydrogen storage material, it can achieve a wide range of pressurization from low-pressure by-product hydrogen (0.2 MPa) to ultra-high-pressure hydrogen (70 MPa), making it compatible with various hydrogen supply scenarios such as industrial hydrogen production, water electrolysis hydrogen production, and by-product hydrogen.

[0060] The following combination Figures 1 to 5 Each specific application implementation method is described in detail.

[0061] Specific application example 1: Two-tank two-stage scheme.

[0062] like Figure 1 As shown, in this embodiment, the system includes a first compression tank 11 and a second compression tank 12. The first compression tank 11 is filled with a low-pressure hydrogen storage material (such as a LaNi5 alloy with a hydrogen absorption equilibrium pressure of about 2 MPa), and the second compression tank 12 is filled with a high-pressure hydrogen storage material (such as a TiCr alloy with a hydrogen absorption equilibrium pressure of about 9 MPa).

[0063] In the first state, the first part of the compression tank is the second compression tank 12, the second part of the compression tank is the first compression tank 11, the second compression tank 12 releases hydrogen, and the first compression tank 11 absorbs hydrogen.

[0064] Specifically: close the first electronic expansion valve 005, open the second electronic expansion valve 006, and switch the intake three-way valve 002, exhaust three-way valve 003, and temperature control three-way valve 004 so that the refrigerant flow direction is: refrigerant compressor outlet → internal heat exchanger of the second compression tank 12 → second electronic expansion valve 006 → internal heat exchanger of the first compression tank 11 → refrigerant compressor inlet.

[0065] Hydrogen release from the second compression tank 12: High-temperature and high-pressure refrigerant enters the heat exchanger inside the second compression tank 12, releasing heat to the high-pressure hydrogen storage material inside the tank, heating it to about 120 to 150°C. After absorbing heat, the high-pressure hydrogen storage material releases high-pressure hydrogen gas (about 35 MPa), which is then transported to the high-pressure hydrogen storage cylinder group 10 via one-way valve 103. The temperature of the refrigerant working fluid drops to about 60 to 80°C after releasing heat to the hydrogen storage material.

[0066] Hydrogen absorption in the first compression tank 11: The cooled refrigerant flows through the second electronic expansion valve 006, throttles and expands to a low-pressure and low-temperature state (about 5 to 10°C), and enters the heat exchanger inside the first compression tank 11. It absorbs heat from the low-pressure hydrogen storage material inside the tank to cool it to about 10 to 30°C. After cooling, the low-pressure hydrogen storage material absorbs hydrogen from the low-pressure hydrogen source (about 2MPa) until it is saturated, forming a metal hydride. At the same time, the refrigerant working fluid absorbs the heat released during the hydrogen absorption process of the hydrogen storage material and flows back to the inlet of the refrigerant compressor to complete a single cycle.

[0067] In the second state, the first part of the compression tank is the second compression tank 12, and the second part of the compression tank is the first compression tank 11. The first compression tank 11 releases hydrogen, and the second compression tank 12 absorbs hydrogen.

[0068] Specifically: close the second electronic expansion valve 006, open the first electronic expansion valve 005, and switch the intake three-way valve 002, exhaust three-way valve 003, and temperature control three-way valve 004 to make the refrigerant flow direction as follows: refrigerant compressor outlet → internal heat exchanger of the first compression tank 11 → first electronic expansion valve 005 → internal heat exchanger of the second compression tank 12 → refrigerant compressor inlet.

[0069] Hydrogen is released from the first compression tank 11: The high-temperature and high-pressure refrigerant enters the heat exchanger inside the first compression tank 11 and releases heat to the low-pressure hydrogen storage material inside the tank, heating it to about 120 to 150°C. After absorbing the heat, the low-pressure hydrogen storage material releases medium-pressure hydrogen (about 9 MPa), which is then transported to the second compression tank 12 through the one-way valve 102. The temperature of the refrigerant decreases after releasing heat to the hydrogen storage material.

[0070] Hydrogen absorption in the second compression tank 12: The cooled refrigerant flows through the first electronic expansion valve 005, expands to a low temperature state by throttling, and enters the heat exchanger inside the second compression tank 12. It absorbs heat from the high-pressure hydrogen storage material inside the tank to cool it down. After cooling, the high-pressure hydrogen storage material absorbs medium-pressure hydrogen from the first compression tank 11 until it is saturated, forming a metal hydride. At the same time, the refrigerant working fluid absorbs the heat released during the hydrogen absorption process of the hydrogen storage material and flows back to the inlet of the refrigerant compressor.

[0071] By repeating the first and second stages, hydrogen is continuously compressed in two stages from 2 MPa to 35 MPa. This method is suitable for applications with an inlet hydrogen pressure of approximately 2 MPa, such as hydrogen production through water electrolysis and industrial by-product hydrogen production.

[0072] Specific application example 2: Two-tank single-stage solution.

[0073] like Figure 2 As shown, in this embodiment, the system includes a third compression tank 21 and a fourth compression tank 22, and the third compression tank 21 and the fourth compression tank 22 are filled with hydrogen storage materials with the same pressure platform.

[0074] In the first state, the first part of the compression tank is the fourth compression tank 22, the second part of the compression tank is the third compression tank 21, the fourth compression tank 22 releases hydrogen to the high-pressure hydrogen storage cylinder group 10, and the third compression tank 21 absorbs hydrogen from the low-pressure hydrogen source.

[0075] Specifically: Close the first electronic expansion valve 005, open the second electronic expansion valve 006, and switch the intake three-way valve 002, exhaust three-way valve 003, and temperature control three-way valve 004 to make the refrigerant flow direction as follows: refrigerant compressor outlet → internal heat exchanger of the fourth compression tank 22 → second electronic expansion valve 006 → internal heat exchanger of the third compression tank 21 → refrigerant compressor inlet.

[0076] Hydrogen release from the fourth compression tank 22: High-temperature and high-pressure refrigerant enters the heat exchanger inside the fourth compression tank 22, heating the hydrogen storage material inside the tank and causing it to release high-pressure hydrogen gas (about 35MPa), which is then transported to the high-pressure hydrogen storage cylinder group 10 via one-way valve 204.

[0077] Hydrogen absorption in the third compression tank 21: After the refrigerant is cooled by the second electronic expansion valve 006, it enters the heat exchanger in the third compression tank 21 to cool the hydrogen storage material in the tank, so that it absorbs hydrogen from the low-pressure hydrogen source (about 9MPa) until it is saturated.

[0078] In the second state, the first part of the compression tank is the fourth compression tank 22, the second part of the compression tank is the third compression tank 21, the third compression tank 21 releases hydrogen to the high-pressure hydrogen storage cylinder group 10, and the fourth compression tank 22 absorbs hydrogen from the low-pressure hydrogen source.

[0079] The valve operation is symmetrical to the first stage, and the refrigerant flows sequentially through the third compression tank 21 → the first electronic expansion valve 005 → the fourth compression tank 22.

[0080] Two compression tanks alternately draw in and release hydrogen, each independently supplying high-pressure hydrogen to the high-pressure hydrogen storage cylinder group 10. This scheme is suitable for scenarios with high inlet hydrogen pressure (approximately 9 MPa), and can directly boost the pressure to 35 MPa without staged compression, resulting in a simpler system structure.

[0081] Specific application example 3: Four-tank two-stage scheme.

[0082] like Figure 3 As shown, in this embodiment, the system includes a fifth compression tank 31, a sixth compression tank 33, a seventh compression tank 32, and an eighth compression tank 34. The fifth compression tank 31 and the seventh compression tank 32 are filled with low-pressure hydrogen storage material, while the sixth compression tank 33 and the eighth compression tank 34 are filled with high-pressure hydrogen storage material.

[0083] In the first state, the first part of the compression tanks are the seventh compression tank 32 and the eighth compression tank 34, and the second part of the compression tanks are the sixth compression tank 33 and the fifth compression tank 31.

[0084] Specifically: Close the first electronic expansion valve 005, open the second electronic expansion valve 006, and switch the intake three-way valve 002, exhaust three-way valve 003, and temperature control three-way valve 004 to make the refrigerant flow direction as follows: refrigerant compressor outlet → seventh compression tank 32 → eighth compression tank 34 → second electronic expansion valve 006 → sixth compression tank 33 → fifth compression tank 31 → refrigerant compressor inlet.

[0085] Hydrogen is released from the seventh compression tank 32 and the eighth compression tank 34: the refrigerant flows sequentially through the two hydrogen release tanks, heating the hydrogen storage material inside. The medium-pressure hydrogen released from the seventh compression tank 32 is transported to the sixth compression tank 33 via the one-way valve 304, and the high-pressure hydrogen released from the eighth compression tank 34 is transported to the high-pressure hydrogen storage cylinder group 10 via the one-way valve 305.

[0086] Hydrogen absorption in the sixth compression tank 33 and the fifth compression tank 31: After the refrigerant is throttled and cooled by the second electronic expansion valve 006, it flows sequentially through the two hydrogen absorption tanks, cooling the hydrogen storage material inside. The fifth compression tank 31 absorbs hydrogen from a low-pressure hydrogen source, and the sixth compression tank 33 absorbs medium-pressure hydrogen from the seventh compression tank 32.

[0087] In the second state, the first part of the compression tanks are the seventh compression tank 32 and the eighth compression tank 34, and the second part of the compression tanks are the sixth compression tank 33 and the fifth compression tank 31. The refrigerant flows sequentially through the fifth compression tank 31, the sixth compression tank 33, the throttling element, the eighth compression tank 34, and the seventh compression tank 32.

[0088] After the valve action is switched, the refrigerant flow reverses, and the two sets of compressor tanks switch roles.

[0089] This solution, through a dual-tank configuration at each stage, increases the hydrogen processing flow rate per unit time while maintaining the compression ratio of the two stages, making it suitable for scenarios with high-flow-rate compression requirements.

[0090] Specific application example four: Three-tank three-level scheme.

[0091] like Figure 4 As shown, in this embodiment, the system includes a ninth compression tank 41, a tenth compression tank 43, and an eleventh compression tank 42. The ninth compression tank 41 contains low-pressure hydrogen storage material, the eleventh compression tank 42 contains medium-pressure hydrogen storage material, and the tenth compression tank 43 contains high-pressure hydrogen storage material.

[0092] In the first state, the first part of the compression tank is the ninth compression tank 41 and the tenth compression tank 43, and the second part of the compression tank is the eleventh compression tank 42.

[0093] Specifically: Close the first electronic expansion valve 005, open the second electronic expansion valve 006, switch the three-way valve, and make the refrigerant flow direction as follows: refrigerant compressor outlet → ninth compression tank 41 → tenth compression tank 43 → second electronic expansion valve 006 → eleventh compression tank 42 → refrigerant compressor inlet.

[0094] Hydrogen release from the ninth compression tank 41 and the tenth compression tank 43: The refrigerant flows through the two hydrogen release tanks in sequence. The medium-pressure hydrogen released from the ninth compression tank 41 is transported to the eleventh compression tank 42 via the one-way valve 402, and the high-pressure hydrogen released from the tenth compression tank 43 is transported to the high-pressure hydrogen storage cylinder group 10 via the one-way valve 404.

[0095] Hydrogen absorption in eleventh compression tank 42: After the refrigerant is throttled and cooled by the second electronic expansion valve 006, it enters the eleventh compression tank 42, which absorbs medium-pressure hydrogen from the ninth compression tank 41 until it is saturated.

[0096] In the second state, the first part of the compression tank consists of the ninth compression tank 41 and the tenth compression tank 43, and the second part of the compression tank consists of the eleventh compression tank 42. The refrigerant flows sequentially through the eleventh compression tank 42, the throttling element, the tenth compression tank 43, and the ninth compression tank 41.

[0097] After the valve operation switches, the refrigerant flow direction is: refrigerant compressor outlet → eleventh compressor tank 42 → first electronic expansion valve 005 → tenth compressor tank 43 → ninth compressor tank 41 → refrigerant compressor inlet. Hydrogen is released from the eleventh compressor tank 42 to the tenth compressor tank 43, while the ninth and tenth compressor tanks simultaneously absorb hydrogen.

[0098] This scheme significantly reduces the lower limit of the inlet pressure to 0.2 MPa through three-stage compression, greatly expanding the system's compatibility with low-grade hydrogen sources such as low-pressure by-product hydrogen and low-quality industrial hydrogen production.

[0099] Specific application example five: Four-tank four-level scheme.

[0100] like Figure 5 As shown, in this embodiment, the system includes a twelfth compression tank 51, a thirteenth compression tank 53, a fourteenth compression tank 52, and a fifteenth compression tank 54. The twelfth compression tank 51 contains low-pressure hydrogen storage material, the fourteenth and thirteenth compression tanks 52 and 53 contain medium-pressure hydrogen storage material, and the fifteenth compression tank 54 contains high-pressure hydrogen storage material.

[0101] In the first state, the first part of the compression tanks are the fourteenth compression tank 52 and the fifteenth compression tank 54, and the second part of the compression tanks are the thirteenth compression tank 53 and the twelfth compression tank 51.

[0102] Specifically: Close the first electronic expansion valve 005, open the second electronic expansion valve 006, switch the three-way valve, and make the refrigerant flow direction as follows: refrigerant compressor outlet → fourteenth compression tank 52 → fifteenth compression tank 54 → second electronic expansion valve 006 → thirteenth compression tank 53 → twelfth compression tank 51 → refrigerant compressor inlet.

[0103] Hydrogen is released from the fourteenth compression tank 52 and the fifteenth compression tank 54: the fourteenth compression tank 52 releases medium and high pressure hydrogen gas, which is then transported to the thirteenth compression tank 53 via one-way valve 503; the fifteenth compression tank 54 releases high pressure hydrogen gas, which is then transported to the high pressure hydrogen storage cylinder group 10 via one-way valve 505.

[0104] Hydrogen absorption by the thirteenth compression tank 53 and the twelfth compression tank 51: After the refrigerant is throttled and cooled by the second electronic expansion valve 006, it flows through the two hydrogen absorption tanks in sequence. The twelfth compression tank 51 absorbs hydrogen from the low-pressure hydrogen source, and the thirteenth compression tank 53 absorbs medium and high-pressure hydrogen from the fourteenth compression tank 52.

[0105] In the second state, the first part of the compression tanks are the fourteenth compression tank 52 and the fifteenth compression tank 54, and the second part of the compression tanks are the thirteenth compression tank 53 and the twelfth compression tank 51. The refrigerant flows sequentially through the twelfth compression tank 51, the thirteenth compression tank 53, the throttling element, the fifteenth compression tank 54, and the fourteenth compression tank 52.

[0106] After the valve action is switched, the refrigerant flow reverses, and the two sets of compressor tanks switch roles.

[0107] Hydrogen is released from the thirteenth compression tank 53 and the twelfth compression tank 51: Hydrogen released from the thirteenth compression tank 53 is transported to the fifteenth compression tank 54 via one-way valve 504, and hydrogen released from the twelfth compression tank 51 is transported to the fourteenth compression tank 52 via one-way valve 502.

[0108] Hydrogen absorption by the fourteenth compression tank 52 and the fifteenth compression tank 54: After the refrigerant is throttled and cooled, it flows through the two hydrogen absorption tanks in sequence. The fourteenth compression tank 52 absorbs hydrogen from the twelfth compression tank 51, and the fifteenth compression tank 54 absorbs hydrogen from the thirteenth compression tank 53.

[0109] This scheme achieves an ultra-high compression ratio from 2MPa to 70MPa through a four-level refined pressure gradient distribution, which significantly improves the hydrogen storage capacity of high-pressure hydrogen storage cylinders.

[0110] Specific application example six: Multi-tank parallel capacity expansion scheme.

[0111] To increase hydrogen compression flow rate, each level of compression tank in any compression tank group can be composed of multiple sub-compression tanks of the same level connected in parallel. For example, the first compression tank 11 can be divided into multiple sub-tanks connected in parallel, and the second compression tank 12 can be divided into multiple sub-tanks connected in parallel. The structure, hydrogen storage materials, and connection methods with the refrigerant circuit of each sub-tank are the same. After being connected in parallel, hydrogen absorption or release operations are performed synchronously, thereby increasing the hydrogen processing flow rate many times over while maintaining the same compression ratio.

[0112] Specific application example seven: Real-time closed-loop control of throttling element.

[0113] The opening degrees of the first electronic expansion valve 005 and the second electronic expansion valve 006 are adjusted in real time according to the temperature and pressure of the compression tank. Specifically, temperature and pressure sensors are installed in each compression tank. The control unit collects the temperature and pressure data of each tank in real time. Based on the preset optimal operating conditions for the hydrogen absorption and desorption reaction (such as the hydrogen absorption temperature of the first compression tank 11 being 0 to 10°C and the hydrogen release temperature of the second compression tank 12 being 80 to 100°C), the opening degree of the corresponding electronic expansion valve is dynamically adjusted to control the flow rate and evaporation / condensation temperature of the refrigerant, ensuring that the hydrogen absorption and desorption reaction always operates within the optimal operating range. This control strategy effectively solves the problem of drastic temperature fluctuations caused by the reaction heat effect during the hydrogen absorption and desorption process of hydrogen storage materials (hydrogen absorption releasing heat raises the temperature, inhibiting further hydrogen absorption, while hydrogen release absorbing heat lowers the temperature, inhibiting further hydrogen release), which affects the reaction rate and compression efficiency.

[0114] Based on the description and inspiration of the above-mentioned specific application embodiments, the principle of the innovative technology of the present invention in solving the problems of the prior art and the excellent technical effects achieved are further analyzed here.

[0115] I. This invention eliminates multiple heat exchange stages, significantly improving thermal response speed and energy utilization efficiency.

[0116] In the existing technology, the condenser and evaporator of the heat pump are both external. The refrigerant needs to exchange heat with the heat transfer fluid (water, oil, etc.) first, and the heat transfer fluid is then circulated back to the compression tank to exchange heat with the hydrogen storage material. This multiple heat exchange path of "refrigerant → heat transfer fluid → hydrogen storage material" has the following problems: (1) heat loss occurs every time heat exchange occurs; (2) the heat capacity of the heat transfer fluid increases the thermal inertia of the system, resulting in a lag in temperature change; (3) the circulation of the heat transfer fluid requires additional pump power consumption; (4) the heat exchange between the heat transfer fluid and the hydrogen storage material is limited by the thermal conductivity of the pressure bearing wall.

[0117] This invention completely eliminates the intermediate heat transfer fluid step, directly introducing the refrigerant into the internal heat exchanger within the compression tank for direct heat exchange with the hydrogen storage material. The refrigerant undergoes a complete thermodynamic cycle in a reverse Carnot cycle, sequentially performing compression (heat and pressure increase), condensation and heat release (heat release to the hydrogen storage material within the hydrogen release tank), throttling and expansion (heat and pressure decrease), and evaporation and heat absorption (heat absorption from the hydrogen storage material within the hydrogen absorption tank). The high-temperature, high-pressure refrigerant directly releases heat to the hydrogen storage material within the hydrogen release tank (equivalent to a condenser function built into the tank), while the throttled, low-temperature refrigerant directly absorbs heat from the hydrogen storage material within the hydrogen absorption tank (equivalent to an evaporator function built into the tank). This design eliminates all intermediate heat exchange steps, significantly improving thermal response speed and energy utilization efficiency.

[0118] II. This invention achieves tiered utilization of cold and hot energy through a single-path series circulation.

[0119] In existing technologies, heating and cooling are accomplished through independent circuits, with each circuit operating independently. This invention employs a design where the refrigerant flows through two sets of compression tanks in series via a single path: the high-temperature, high-pressure refrigerant first flows through the hydrogen release tank (releasing heat and cooling), then undergoes further cooling via an electronic expansion valve, and finally flows through the hydrogen absorption tank (absorbing heat and heating), before returning to the compressor inlet to complete the cycle. During this process, the heat released by the refrigerant in the hydrogen release tank is carried to the hydrogen absorption tank side, where it is further cooled by throttling and then used to cool the hydrogen absorption tank, achieving the cascade utilization and recovery of thermal energy.

[0120] Third, the extremely simple valve control architecture of this invention achieves high integration.

[0121] Existing technologies require four three-way switching valves in conjunction with two main circulation loops and four bypass branches to complete the hot / cold switching; some solutions require eight switching valves. This invention requires only three three-way switching valves to complete all hot / cold switching functions: the combined switching of the intake three-way valve 002, the exhaust three-way valve 003, and the temperature-controlled three-way valve 004 switches the refrigerant circuit between two states. Combined with the alternating opening and closing of two electronic expansion valves, this achieves complete reversal of the refrigerant flow between the two sets of compression tanks. This significant reduction in the number of valves directly brings multiple benefits, including simplified system piping, reduced size, simplified control logic, and improved reliability.

[0122] IV. The modular hierarchical compression architecture of this invention enables wide pressure range adaptation.

[0123] In existing technologies, the number of compression stages in metal hydride compression systems is usually fixed, making it difficult to adapt to different inlet pressure scenarios. This invention achieves modular expansion from single-stage to four-stage by customizing hydrogen storage alloys for different pressure platforms and flexibly configuring the number and number of compression tanks. It includes two-tank two-stage solutions (2MPa→35MPa), two-tank single-stage solutions (9MPa→35MPa), three-tank three-stage solutions (0.2MPa→35MPa), and four-tank four-stage solutions (2MPa→70MPa), which can flexibly adapt to various hydrogen supply scenarios, from low-pressure by-product hydrogen to high-pressure industrial hydrogen.

[0124] In summary, this invention achieves the following comprehensive technical effects through its core architectural innovation of "direct refrigerant supply with internal heat exchange + three-valve switching": (1) it eliminates multiple heat exchange links, significantly improves thermal response speed, and accelerates hydrogen absorption and desorption reaction rates; (2) it utilizes cold and heat energy in a cascade manner, significantly reducing system energy consumption; (3) it requires only three switching valves, greatly simplifying the system structure and significantly improving integration; (4) its modular, staged compression architecture can flexibly adapt to a wide pressure range from 0.2 MPa to 70 MPa, and is compatible with various hydrogen supply scenarios. Compared with existing technologies, this invention has made significant progress in compression efficiency, energy consumption, integration, and adaptability.

[0125] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A metal hydride compression system, characterized in that: The system includes a reverse Carnot cycle unit and a metal hydride compression tank assembly. The reverse Carnot cycle unit has a refrigerant circuit for circulating refrigerant. The metal hydride compression tank assembly includes at least two compression tanks, each equipped with an internal heat exchanger connected in series in the refrigerant circuit. The refrigerant directly exchanges heat with the hydrogen storage material inside the tank as it flows through the internal heat exchanger. The refrigerant circuit is equipped with three three-way switching valves and a throttling element, used to switch the refrigerant circuit between two connection states through the switching of the three three-way switching valves and the alternating conduction of the throttling element: In the first state, the refrigerant in the refrigerant circuit flows sequentially through the internal heat exchanger of the first compression tank, the throttling element, and the internal heat exchanger of the second compression tank. The high-temperature and high-pressure refrigerant flowing through the internal heat exchanger of the first compression tank releases heat to the hydrogen storage material, causing it to heat up and release hydrogen. The low-temperature refrigerant, after being throttled and cooled by the throttling element, absorbs heat from the hydrogen storage material when it flows through the internal heat exchanger of the second compression tank, causing it to cool down and absorb hydrogen. In the second state, the refrigerant in the refrigerant circuit flows sequentially through the internal heat exchanger of the second part of the compression tank, the throttling element, and the internal heat exchanger of the first part of the compression tank. The high-temperature and high-pressure refrigerant flowing through the internal heat exchanger of the second part of the compression tank releases heat to the hydrogen storage material, causing it to heat up and release hydrogen. The low-temperature refrigerant, after being throttled and cooled by the throttling element, absorbs heat from the hydrogen storage material when it flows through the internal heat exchanger of the first part of the compression tank, causing it to cool down and absorb hydrogen.

2. The metal hydride compression system according to claim 1, characterized in that, The three three-way switching valves are an intake three-way switching valve (002), an exhaust three-way switching valve (003), and a temperature control three-way switching valve (004); the throttling element includes a first electronic expansion valve (005) and a second electronic expansion valve (006) disposed on the refrigerant circuit. The first electronic expansion valve (005) and the second electronic expansion valve (006) are respectively disposed on two parallel branches between the first part of the compression tank and the second part of the compression tank, and are respectively connected in series in the two parallel branches. In the first state, the second electronic expansion valve (006) is open and the first electronic expansion valve (005) is closed. In the second state, the first electronic expansion valve (005) is open and the second electronic expansion valve (006) is closed.

3. The metal hydride compression system according to claim 1, characterized in that, The reverse Carnot cycle unit also includes a water circulation loop, which includes an air-cooled heat exchanger (008) and a water pump (009). The water circulation loop and the refrigerant loop exchange heat through a heat exchanger (007).

4. The metal hydride compression system according to claim 1, characterized in that, It includes a first compression tank (11) and a second compression tank (12). The first compression tank (11) is filled with low-pressure hydrogen storage material, and the second compression tank (12) is filled with high-pressure hydrogen storage material. In the first state, the refrigerant flows sequentially through the second compression tank (12), the throttling element, and the first compression tank (11). The second compression tank (12) releases hydrogen to the high-pressure hydrogen storage cylinder group (10), and the first compression tank (11) draws hydrogen from the low-pressure hydrogen source. In the second state, the refrigerant flows sequentially through the first compression tank (11), the throttling element, and the second compression tank (12). The first compression tank (11) releases hydrogen to the second compression tank (12), and the second compression tank (12) draws hydrogen from the first compression tank (11).

5. The metal hydride compression system according to claim 1, characterized in that, It includes a third compression tank (21) and a fourth compression tank (22), wherein the third compression tank (21) and the fourth compression tank (22) are filled with hydrogen storage materials with the same pressure platform; in the first state, the refrigerant flows sequentially through the fourth compression tank (22), the throttling element, and the third compression tank (21), the fourth compression tank (22) releases hydrogen to the high-pressure hydrogen storage cylinder group (10), and the third compression tank (21) absorbs hydrogen from the low-pressure hydrogen source; in the second state, the refrigerant flows sequentially through the third compression tank (21), the throttling element, and the fourth compression tank (22), the third compression tank (21) releases hydrogen to the high-pressure hydrogen storage cylinder group (10), and the fourth compression tank (22) absorbs hydrogen from the low-pressure hydrogen source.

6. The metal hydride compression system according to claim 1, characterized in that, The system includes a fifth compression tank (31), a sixth compression tank (33), a seventh compression tank (32), and an eighth compression tank (34). The fifth compression tank (31) and the seventh compression tank (32) are filled with low-pressure hydrogen storage material, while the sixth compression tank (33) and the eighth compression tank (34) are filled with high-pressure hydrogen storage material. In the first state, the seventh compression tank (32) releases hydrogen to the sixth compression tank (33), and the eighth compression tank (34) releases hydrogen to the high-pressure hydrogen storage cylinder group (10). The fifth compression tank (31) draws hydrogen from the low-pressure hydrogen source, and the sixth compression tank (33) draws hydrogen from the seventh compression tank (32). The refrigerant flows sequentially. The refrigerant flows sequentially through the seventh compression tank (32), the eighth compression tank (34), the throttling element, the sixth compression tank (33), and the fifth compression tank (31). In the second state, the fifth compression tank (31) releases hydrogen to the eighth compression tank (34), the sixth compression tank (33) releases hydrogen to the high-pressure hydrogen storage cylinder group (10), the seventh compression tank (32) draws hydrogen from the low-pressure hydrogen source, and the eighth compression tank (34) draws hydrogen from the fifth compression tank (31).

7. The metal hydride compression system according to claim 1, characterized in that, The system includes a ninth compression tank (41), a tenth compression tank (43), and an eleventh compression tank (42). The ninth compression tank (41) contains low-pressure hydrogen storage material, the eleventh compression tank (42) contains medium-pressure hydrogen storage material, and the tenth compression tank (43) contains high-pressure hydrogen storage material. In the first state, hydrogen is released from the ninth compression tank (41) to the eleventh compression tank (42), hydrogen is released from the tenth compression tank (43) to the high-pressure hydrogen storage cylinder group (10), and the eleventh compression tank (42) draws hydrogen from the ninth compression tank (41). Hydrogen and refrigerant flow sequentially through the ninth compression tank (41), the tenth compression tank (43), the throttling element, and the eleventh compression tank (42); in the second state, the eleventh compression tank (42) releases hydrogen to the tenth compression tank (43), the ninth compression tank (41) draws hydrogen from the low-pressure hydrogen source, and the tenth compression tank (43) draws hydrogen from the eleventh compression tank (42). The refrigerant flows sequentially through the eleventh compression tank (42), the throttling element, the tenth compression tank (43), and the ninth compression tank (41).

8. The metal hydride compression system according to claim 1, characterized in that, The system includes a twelfth compression tank (51), a thirteenth compression tank (53), a fourteenth compression tank (52), and a fifteenth compression tank (54). The twelfth compression tank (51) contains low-pressure hydrogen storage material, the fourteenth compression tank (52) and the thirteenth compression tank (53) contain medium-pressure hydrogen storage material, and the fifteenth compression tank (54) contains high-pressure hydrogen storage material. In the first state, the fourteenth compression tank (52) releases hydrogen to the thirteenth compression tank (53), and the fifteenth compression tank (54) releases hydrogen to the high-pressure hydrogen storage cylinder group (10). The twelfth compression tank (51) draws hydrogen from the low-pressure hydrogen source, and the thirteenth compression tank (53) draws hydrogen from the fourteenth compression tank (52). The refrigerant flows sequentially through the fourteenth compression tank (52), the fifteenth compression tank (54), the throttling element, the thirteenth compression tank (53), and the twelfth compression tank (51). In the second state, hydrogen is released from the twelfth compression tank (51) to the fourteenth compression tank (52), and hydrogen is released from the thirteenth compression tank (53) to the fifteenth compression tank (54). The fourteenth compression tank (52) draws hydrogen from the twelfth compression tank (51), and the fifteenth compression tank (54) draws hydrogen from the thirteenth compression tank (53). The refrigerant flows sequentially through the twelfth compression tank (51), the thirteenth compression tank (53), the throttling element, the fifteenth compression tank (54), and the fourteenth compression tank (52).

9. The metal hydride compression system according to any one of claims 4 to 8, characterized in that, Each of the compression tanks is equipped with a mechanical check valve on its hydrogen outlet pipeline, which is used to automatically open or close according to the pressure difference between the two ends; the high-pressure hydrogen storage cylinder group (10) is connected to a safety unloading valve, which automatically opens to release pressure when the pressure of the high-pressure hydrogen storage cylinder group (10) exceeds a set threshold.

10. A method for compressing metal hydrides, employing the metal hydride compression system according to any one of claims 1 to 9, characterized in that, The process includes alternating first and second stages: First stage: Switching the refrigerant circuit, causing the refrigerant to flow sequentially through the refrigerant compressor outlet, the internal heat exchanger of the first part of the compression tank, the throttling element, the internal heat exchanger of the second part of the compression tank, and the refrigerant compressor inlet; the first part of the compression tank is heated to release hydrogen, and the second part of the compression tank is cooled to draw in hydrogen; Second stage: Switch the refrigerant circuit so that the refrigerant flows sequentially through the refrigerant compressor outlet, the internal heat exchanger of the second part of the compression tank, the throttling element, the internal heat exchanger of the first part of the compression tank, and the refrigerant compressor inlet; the second part of the compression tank is heated and releases hydrogen, while the first part of the compression tank is cooled and draws in hydrogen; repeat the first stage and the second stage to achieve continuous compression of hydrogen.

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