Liquid hydrogen system

Abstract

The utility model provides a liquid hydrogen system capable of further improving energy efficiency. A liquid hydrogen system (10) is characterized by being provided with: a hydrogen tank (12) for storing liquid hydrogen in a vehicle; a supply line (20) for taking out the liquid hydrogen from the hydrogen tank (12), converting the liquid hydrogen into hydrogen gas, and supplying the hydrogen gas to a hydrogen engine (100); an evaporation flow path (40) for guiding the evaporation gas in the hydrogen tank (12) to the outside of the tank; and a fuel cell (50) that is provided in the evaporation flow path (40) and that generates electricity by means of the evaporation gas and air.

Description

Technical Field

[0001] This specification discloses a liquid hydrogen system for storing liquid hydrogen in a vehicle equipped with a hydrogen engine. Background Technology

[0002] In recent years, vehicles equipped with hydrogen engines have been proposed. These vehicles require the storage of large quantities of hydrogen. Therefore, solutions have been proposed for storing hydrogen in a liquid state within the vehicle. For example, Patent Document 1 discloses a liquid hydrogen system with a hydrogen tank for storing liquid hydrogen. This liquid hydrogen system also includes a first flow channel connecting the hydrogen tank to the outside of the vehicle and a safety valve disposed in the first flow channel. With this structure, the vaporized gas that naturally vaporizes inside the hydrogen tank is released to the outside of the vehicle, thus preventing excessive pressure rise in the hydrogen tank.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2024-006562 Utility Model Content

[0004] Problems to be solved by the utility model

[0005] However, in Patent Document 1, the evaporated gas is either released into the air through a reaction or directly outside the vehicle, thus failing to effectively utilize the evaporated gas. Therefore, there is room for improvement in energy efficiency in the technology of Patent Document 1.

[0006] Therefore, this specification discloses a liquid hydrogen system that can further improve energy efficiency.

[0007] Methods for solving problems

[0008] The liquid hydrogen system disclosed in this specification is characterized by comprising: a hydrogen tank for storing liquid hydrogen inside a vehicle; a supply line for converting the liquid hydrogen from the hydrogen tank into hydrogen gas and supplying it to a hydrogen engine; an evaporation channel for guiding the evaporated gas inside the hydrogen tank to the outside of the tank; and a fuel cell disposed in the evaporation channel for generating electricity using the evaporated gas and air.

[0009] Utility Model Effect

[0010] According to the liquid hydrogen system disclosed in this specification, energy efficiency can be further improved by using the evaporated gas for power generation in the fuel cell. Attached Figure Description

[0011] Figure 1 This is a diagram showing a portion of the structure of a liquid hydrogen system.

[0012] Figure 2 This is a diagram showing another part of the structure of the liquid hydrogen system. Detailed Implementation

[0013] The structure of the liquid hydrogen system 10 will now be described with reference to the accompanying drawings. Figure 1 as well as Figure 2 This is a schematic diagram showing the structure of the liquid hydrogen system 10. The liquid hydrogen system 10 is mounted on a vehicle and stores hydrogen in a liquid state. The vehicle is a hydrogen engine automobile equipped with a hydrogen engine 100.

[0014] The liquid hydrogen system 10 includes a hydrogen tank 12 for storing liquid hydrogen. The hydrogen tank 12 stores the liquid hydrogen in an insulated manner. For example, a container with a double-tube structure, consisting of an inner tank made of SUS and an outer tank covering the inner tank, can be used as such a tank 12. Furthermore, to maintain a uniform pressure applied to the inner wall, the hydrogen tank 12 is spherical or... Figure 1 The oblong shape shown.

[0015] In hydrogen tank 12, liquid hydrogen is maintained at a cryogenic temperature. Furthermore, the pressure of the liquid hydrogen within hydrogen tank 12 is approximately the same as or slightly higher than atmospheric pressure, for example, below 1 MPa. A hydrogen pump 16 is installed in hydrogen tank 12. Hydrogen pump 16 draws liquid hydrogen from hydrogen tank 12 and delivers it to the hydrogen engine 100. In this example, the hydrogen pump 16 is a booster pump that simultaneously pressurizes and draws liquid hydrogen. The hydrogen pump 16 is driven by a pump motor 18. Figure 1 As shown, the pump motor 18 is located outside the hydrogen tank 12.

[0016] Liquid hydrogen discharged from hydrogen pump 16 passes through Figure 2 The supply line 20 shown is supplied to the hydrogen engine 100. The supply line 20 has a supply channel 22, a vaporizer 24, a pressure chamber 26, and a supply pressure reducing valve 28. The supply channel 22 is a channel that guides hydrogen discharged from the hydrogen pump 16 to the hydrogen engine 100.

[0017] The vaporizer 24 is a heat exchanger that converts liquid hydrogen into hydrogen gas by exchanging heat between liquid hydrogen and refrigerant. A pressure chamber 26 is located downstream of the vaporizer 24. The pressure chamber 26 is a container for temporarily storing the hydrogen gas output from the vaporizer 24. The capacity of the pressure chamber 26 is sufficient to cover the degree of response delay in hydrogen supply control. By providing such a pressure chamber 26, hydrogen shortage can be prevented even if the hydrogen consumption of the hydrogen engine 100 changes drastically.

[0018] A supply pressure reducing valve 28 is provided downstream of the vaporizer 24. The supply pressure reducing valve 28 reduces the pressure of the hydrogen to a pressure suitable for the hydrogen engine 100. The reduced-pressure hydrogen is supplied to the hydrogen engine 100 via the injector 30. The flow rate of the hydrogen supplied to the hydrogen engine 100 is detected by the flow meter 32.

[0019] Here, as Figure 1 As shown, there is always a space of more than a predetermined volume at the top of the hydrogen tank 12 (hereinafter referred to as the "upper space"). Hydrogen gas generated from the vaporization of the liquid hydrogen stored in the tank is retained in this upper space. Moreover, as the amount of retained hydrogen gas increases, the pressure inside the hydrogen tank 12 will naturally increase as well. In order to prevent the pressure inside the tank from rising excessively, a discharge channel 34 and an evaporation channel 40 are also provided in the liquid hydrogen system 10.

[0020] The evaporation channel 40 is a channel that guides the hydrogen gas (evaporation gas) inside the hydrogen tank 12 outwards due to the internal pressure. By releasing a portion of the hydrogen gas outwards, it prevents the internal pressure of the hydrogen tank 12 from becoming excessively high. Here, as... Figure 1 As shown, in this example, the evaporation channel 40 branches into two systems: a first channel 42 and a second channel 44. The structures of the first channel 42 and the second channel 44 will be described in detail later.

[0021] The vent channel 34 is a channel that guides a large amount of hydrogen gas out of the tank when it is generated in a short period of time. The vent channel 34 opens when the internal pressure of the tank exceeds a predetermined allowable pressure, thus guiding the hydrogen gas inside the hydrogen tank 12 to the outside of the vehicle. The vent channel 34 can be a single system or multiple systems. Figure 1 The illustrated discharge channel 34 includes a first discharge channel 34a equipped with a solenoid valve 66 and a second discharge channel 34b equipped with a blast-proof disc 68. The solenoid valve 66 opens and closes according to the internal pressure of the tank. On the other hand, the blast-proof disc 68 remains open even if it is irreversibly damaged when the internal pressure of the tank exceeds a predetermined allowable pressure. By providing such a discharge channel 34, even if a large amount of hydrogen gas is generated in a short period of time, to a degree that cannot be handled by the evaporation channel 40 alone, an increase in the internal pressure can be prevented.

[0022] Next, the structure of the evaporation channel 40 will be described in detail. As mentioned above, the evaporation channel 40 in this example branches into a first channel 42 and a second channel 44. Figure 1 As shown, a fuel cell 50 is disposed in the first flow channel 42. The fuel cell 50 is a generator that produces electricity through the electrochemical reaction of hydrogen with air (more precisely, oxygen contained in the air). In this example, evaporated gas (i.e., hydrogen) is supplied to the fuel cell 50 through the first flow channel 42. Thus, the fuel cell 50 generates electricity and water. The electricity generated by the fuel cell 50 is stored in the vehicle battery 110. The electricity from the vehicle battery 110 is used to drive vehicle auxiliary equipment (such as air conditioning), drive the starter motor (not shown) of the hydrogen engine 100, etc. In addition, the water generated as a by-reaction is separated into gas and liquid by the gas-liquid separator 52 and then discarded outside the vehicle.

[0023] Furthermore, existing liquid hydrogen systems also include an evaporation channel that guides the hydrogen gas (i.e., the evaporated gas) inside the hydrogen tank 12 to the outside. However, in existing liquid hydrogen systems, the evaporated gas is simply exhausted outside the vehicle. Therefore, the utilization efficiency of hydrogen in existing liquid hydrogen systems is poor. On the other hand, in this example, as described above, the hydrogen gas (evaporated gas) discharged from the hydrogen tank 12 is not merely wasted, but is effectively utilized as driving energy for vehicle auxiliary equipment, etc. As a result, according to this example, the utilization efficiency of hydrogen can be improved compared to the prior art.

[0024] Additionally, in the first flow channel 42, upstream of the fuel cell 50, a pressure reducing valve 48 and a flow interrupter valve 46 are provided. The pressure reducing valve 48 reduces the pressure of the evaporated gas discharged from the hydrogen tank 12 to a pressure suitable for power generation in the fuel cell 50. Furthermore, the flow interrupter valve 46 is, in principle, always open. Such a flow interrupter valve 46 is closed only when it is desired to actively stop power generation by the fuel cell 50, for example, only in the event of a malfunction in the fuel cell 50.

[0025] The second flow channel 44 is a flow channel that guides the remaining evaporated gas that cannot be completely discharged by the first flow channel 42 to the outside of the vehicle. For example, when the amount of evaporated gas generated per unit time is greater than the amount of hydrogen consumed in the fuel cell 50, or when the on-board battery 110 is fully charged and the power generation in the fuel cell 50 can no longer continue, the evaporated gas flows into the second flow channel 44. A check valve 62 and a reaction section 56 are provided in the second flow channel 44. The check valve 62 only opens when the back pressure is above a predetermined opening pressure. The opening pressure of the check valve 62 is sufficiently high compared to the output pressure of the pressure reducing valve 48. Therefore, the evaporated gas preferentially flows to the fuel cell 50, and only the remaining evaporated gas that cannot be consumed by the fuel cell 50 is delivered to the reaction section 56.

[0026] The reaction section 56 reacts hydrogen flowing in the second flow channel 44 with air (more precisely, oxygen contained in the air) to convert it into water, which is then released outside the vehicle. To enable this hydrogen reaction, a catalyst 58 and a fan 60 that supplies air to the catalyst 58 are provided in the reaction section 56. The catalyst 58 is a substance that induces the reaction of hydrogen and oxygen to produce water (hereinafter referred to as the "water generation reaction"), such as copper. The fan 60 rotates with the check valve 62 open, while supplying air to the catalyst 58. The water generated in the reaction section 56 is released outside the vehicle. In this way, by converting the remaining vaporized gas into water in the reaction section 56, the remaining vaporized gas can be released outside the vehicle more safely. Furthermore, the second flow channel 44 can discharge the vaporized gas outside the vehicle regardless of the charging rate of the vehicle battery 110. Therefore, by providing a second flow channel 44 in addition to the first flow channel 42, it is possible to more reliably prevent excessive pressure rise inside the tank.

[0027] Here, the situation regarding the generation of evaporated gas will be explained. When the hydrogen pump 16 and even the pump motor 18 are driven to power the hydrogen engine 100, the amount of evaporated gas generated increases due to the heat generated during its operation. By using the evaporated gas generated at this time to generate electricity from the fuel cell 50, the power supplied to the alternator (not shown) can be reduced. That is, an alternator that receives power and generates electricity is usually installed in the vehicle. Moreover, in order to ensure the electricity used in the vehicle, a portion of the output power of the hydrogen engine 100 is supplied to the alternator. However, in this case, since a portion of the power of the hydrogen engine 100 is used to generate electricity, the hydrogen utilization efficiency is correspondingly reduced. In this example, since the evaporated gas is used to generate electricity from the fuel cell 50, the amount of electricity required by the alternator can be reduced or decreased. As a result, the alternator can be miniaturized, or the alternator itself can be eliminated.

[0028] Furthermore, the hydrogen tank 12 is typically well insulated, resulting in a small generation rate per unit time. However, when the vehicle is parked for extended periods, trace amounts of vaporized gas are continuously released. If the fuel cell 50 continues to generate electricity using this vaporized gas, the on-board battery 110 may become fully charged midway. To effectively utilize the continuously generated vaporized gas even after the on-board battery 110 is fully charged, the fuel cell 50 can be electrically connected to an external battery 112 when the vehicle is parked. That is, a connector that can be detached from the external battery 112 can be provided on the vehicle, and the fuel cell 50 can be electrically connected to the external battery 112 via this connector when the vehicle is parked. The external battery 112 typically has a larger capacity than the on-board battery 110, and the power from the external battery 112 can also be used to power electrical products outside the vehicle. By electrically connecting such an external battery 112 to the fuel cell 50, the vaporized gas generated during vehicle parking is not wasted and can be converted into electricity. As a result, the efficiency of hydrogen utilization can be further improved.

[0029] As is evident from the above description, in this example, since the fuel cell 50 is provided in the evaporation channel 40, the hydrogen utilization efficiency can be further improved. Furthermore, the structure described so far is an example; other structures can be appropriately modified as long as the structure described in the utility model content is present. For example, in the above description, a reaction section 56 is provided in the second channel 44, but it is also possible to provide a structure without a reaction section 56 and directly release the remaining evaporated gas to the outside of the vehicle. Moreover, when the temperature of the evaporated gas is low, the power generation efficiency of the fuel cell 50 will decrease. Therefore, a structure for heating the evaporated gas can also be provided between the hydrogen tank 12 and the fuel cell 50. For example, a heater for heating the evaporated gas can also be provided. Furthermore, as another structure, the evaporation channel 40 can pass through the vaporizer 24, and the evaporated gas can be heated in the vaporizer 24.

[0030] Symbol Explanation

[0031] 10…Liquid hydrogen system; 12…Hydrogen tank; 16…Hydrogen pump; 18…Pump motor; 20…Supply line; 22…Supply channel; 24…Vaporizer; 26…Pressure chamber; 28…Supply pressure reducing valve; 30…Injector; 32…Flow meter; 34…Discharge channel; 34a…First discharge channel; 34b…Second discharge channel; 40…Evaporation channel; 42…First channel; 44…Second channel; 46…Break valve; 48…Pressure reducing valve; 50…Fuel cell; 52…Gas-liquid separator; 56…Reaction section; 58…Catalyst; 60…Fan; 62…Check valve; 66…Solenoid valve; 68…Explosion-proof plate; 100…Hydrogen engine; 110…On-board battery; 112…External battery.

Claims

1. A liquid hydrogen system, characterized in that, have: A hydrogen tank, which stores liquid hydrogen inside the vehicle; The supply line takes the liquid hydrogen from the hydrogen tank, converts it into hydrogen gas, and supplies it to the hydrogen engine. An evaporation channel that guides the evaporated gas inside the hydrogen tank to the outside of the tank; A fuel cell is disposed in the evaporation channel and generates electricity through the evaporating gas and air.

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