Hydrogen engine vehicle

Abstract

To improve fuel economy of a hydrogen engine vehicle.SOLUTION: A hydrogen engine vehicle 100 includes a hydrogen engine 10, a hydrogen tank 41 which stores liquid hydrogen, a vaporizer 30 which vaporizes the liquid hydrogen by waste heat of the hydrogen engine 10 and generates hydrogen gas to be supplied to the hydrogen engine 10, and a boil-off line 60 which is connected to the hydrogen tank 41 and discharges boil-off gas vaporized in the hydrogen tank 41 to the outside of the vehicle. The boil-off line 60 includes a second tube 33 which is arranged in the vaporizer 30 and heats the boil-off gas flowing therethrough, and a catalyst 65 which generates water by making air and the boil-off gas react with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to the configuration of hydrogen engine vehicles. [Background technology]

[0002] Patent Document 1 discloses a hydrogen engine vehicle in which liquid hydrogen stored in a hydrogen tank is pressurized with a pump, then vaporized in a vaporizer to store hydrogen gas in a pressure chamber, and the hydrogen gas stored in the pressure chamber is supplied to a hydrogen engine.

[0003] Patent Document 2 discloses a vaporizer that includes a casing through which a heating medium flows and fin tubes through which liquid hydrogen flows, and that vaporizes the liquid hydrogen by performing heat exchange between the liquid hydrogen and the heating medium.

[0004] Patent Document 3 discloses a liquid hydrogen storage system equipped with a boil-off line that releases boil-off gas generated inside the hydrogen tank outside the vehicle. This boil-off line is equipped with a catalyst that converts the boil-off gas into water by reacting it with oxygen in the air. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-6546 [Patent Document 2] Japanese Patent Application Publication No. 2024-5617 [Patent Document 3] Japanese Patent Application Publication No. 2024-6562 Summary of the Invention [Problem to be solved by the invention]

[0006] Liquid hydrogen is stored in a hydrogen tank at an extremely low temperature, and boil-off gas is also at an extremely low temperature. Meanwhile, the catalyst that converts boil-off gas into water by reacting it with oxygen in the air is not activated at low temperatures, and the reaction may be insufficient. For this reason, boil-off gas or air is heated by a heater or the like before being sent to the catalyst to ensure sufficient catalytic reaction. However, heating boil-off gas or air with a heater poses the problem of reduced fuel efficiency.

[0007] Therefore, an object of the present disclosure is to improve the fuel efficiency of hydrogen engine vehicles. [Means for solving the problem]

[0008] The hydrogen engine vehicle of the present disclosure comprises a hydrogen engine, a hydrogen tank for storing liquid hydrogen, a vaporizer that vaporizes the liquid hydrogen using exhaust heat from the hydrogen engine to generate hydrogen gas to be supplied to the hydrogen engine, and a boil-off line connected to the hydrogen tank and discharging boil-off gas vaporized in the hydrogen tank to the outside of the vehicle, wherein the boil-off line is disposed within the vaporizer and comprises a heating flow path that heats the boil-off gas flowing therethrough, and a catalyst that reacts air with the boil-off gas to produce water.

[0009] With this configuration, the boil-off gas is heated using the exhaust heat of the hydrogen engine, which improves fuel efficiency compared to conventional techniques in which the boil-off gas is heated using a heater or the like. [Effects of the Invention]

[0010] The present disclosure can improve the fuel efficiency of hydrogen engine vehicles. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a system diagram showing the configuration of a hydrogen engine vehicle according to an embodiment. [Figure 2] FIG. 2 is a control block diagram of a control unit shown in FIG. [Figure 3] 2 is a side cross-sectional view of the vaporizer shown in FIG. 1. [Figure 4] 4 is a cross-sectional view of the vaporizer taken along line AA in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0012] The configuration of a hydrogen engine vehicle 100 according to an embodiment will now be described with reference to the drawings. As shown in Fig. 1, the hydrogen engine vehicle 100 comprises a hydrogen engine 10, a coolant flow path 15, a heat medium flow path 20, a carburetor 30, a radiator 50, a hydrogen flow path 40, a boil-off line 60, and a control unit 80. In each figure, LH2 represents liquid hydrogen, and H2 represents hydrogen gas.

[0013] The hydrogen engine 10 has an intake port 11 that draws in outside air, a hydrogen gas nozzle 12 that supplies hydrogen gas, and an exhaust port 13 that discharges exhaust gas produced by combustion of the hydrogen gas. The hydrogen engine 10 also has an internal cooling flow path 14 through which cooling water flows to cool the hydrogen engine 10.

[0014] The coolant flow path 15 is connected to the internal cooling flow path 14 and is a flow path through which coolant flows to cool the hydrogen engine 10. A radiator 50 is connected to the coolant flow path 15, which releases the heat of the coolant that has risen in temperature as it flows through the internal cooling flow path 14 of the hydrogen engine 10 to the outside. The coolant flow path 15 is composed of a coolant pump 19, a coolant supply pipe 16, the internal cooling flow path 14, a coolant outlet pipe 17, a radiator coolant flow path 51, and a coolant return pipe 18. The coolant supply pipe 16 connects the outlet of the coolant pump 19 to the inlet of the internal cooling flow path 14 of the hydrogen engine 10. The coolant outlet pipe 17 connects the outlet of the internal cooling flow path 14 to the inlet of the radiator coolant flow path 51. The coolant return pipe 18 connects the outlet of the radiator coolant flow path 51 to the inlet of the coolant pump 19.

[0015] The vaporizer 30 carries a heat transfer medium heated by the exhaust heat of the hydrogen engine 10 and cryogenic liquid hydrogen, and the heat transfer medium vaporizes the liquid hydrogen into hydrogen gas. The vaporizer 30 also heats the boil-off gas vaporized inside the hydrogen tank 41 using the heat transfer medium. The vaporizer 30 is composed of a casing 31, a first tube 32 attached to the inside of the casing 31, and a second tube 33. The casing 31 is provided with a heat transfer medium inlet 31a through which the heat transfer medium flows and a heat transfer medium outlet 31b through which the heat transfer medium flows out. The first tube 32 is a tubular member formed into a spiral shape from a thin tube. Liquid hydrogen flows into the first tube 32 through the first tube inlet 32a, and hydrogen gas flows out through the first tube outlet 32b. Liquid hydrogen and hydrogen gas flow inside the first tube 32, and heat exchange occurs between the liquid hydrogen and the heat transfer medium flowing along the outer surface of the first tube 32. The second tube 33 is a tubular member formed by forming a thin tube into a spiral shape. Low-temperature boil-off gas flows into the second tube 33 from a second tube inlet 33a, and heated boil-off gas flows out from a second tube outlet 33b. The second tube 33 performs heat exchange between the boil-off gas flowing inside and the heat medium flowing on the outer surface, forming a heating flow path that heats the boil-off gas. The structure of the vaporizer 30 will be described in detail later with reference to FIGS. 3 and 4.

[0016] The heat medium flow path 20 is a flow path through which a liquid heat medium flows. The heat medium flow path 20 is composed of a heat medium pump 25, a heat medium supply pipe 21, a radiator heat medium flow path 52, a heat medium outlet pipe 22, a casing 31 of the evaporator 30, a heat medium return pipe 23, a bypass pipe 26, a radiator shutoff valve 27, and a bypass valve 28. The bypass pipe 26 constitutes a bypass flow path.

[0017] The radiator heat medium passage 52 is disposed inside the radiator 50, and heats the low-temperature heat medium by heat exchange with the high-temperature coolant flowing through the radiator coolant passage 51. In this way, the radiator 50 is disposed across the coolant passage 15 and the heat medium passage 20, and is a heat exchanger through which the coolant and the heat medium flow and heat the heat medium with the coolant.

[0018] The heat medium supply pipe 21 connects the outlet of the heat medium pump 25 to the inlet of the radiator heat medium flow path 52. A heat medium temperature sensor 74 is attached to the heat medium supply pipe 21 to detect the heat medium temperature T2 at the outlet of the heat medium pump 25. The heat medium outlet pipe 22 connects the outlet of the radiator heat medium flow path 52 to the heat medium inlet 31a of the casing 31 of the evaporator 30. The heat medium return pipe 23 connects the heat medium outlet 31b of the casing 31 of the evaporator 30 to the inlet of the heat medium pump 25.

[0019] The bypass pipe 26 connects the heat medium supply pipe 21 and the heat medium outlet pipe 22 so as to bypass the radiator heat medium flow path 52. The bypass valve 28 is attached to the bypass pipe 26. The radiator shutoff valve 27 is attached between the outlet of the radiator heat medium flow path 52 and the junction of the heat medium outlet pipe 22 and the bypass pipe 26. The bypass valve 28 and the radiator shutoff valve 27 may be electromagnetic shutoff valves.

[0020] The hydrogen flow path 40 is composed of a hydrogen tank 41, a liquid hydrogen pump 42, a liquid hydrogen supply pipe 43, the first tube 32 of the vaporizer 30, a hydrogen gas outlet pipe 44, a chamber 45, a hydrogen gas supply pipe 46, and a pressure reducing valve 47.

[0021] Hydrogen tank 41 is a tank that stores liquid hydrogen at cryogenic temperatures. Liquid hydrogen supply pipe 43 connects hydrogen tank 41 to first tube inlet 32a. A liquid hydrogen pump 42 that pressurizes liquid hydrogen is attached to liquid hydrogen supply pipe 43. Hydrogen gas outlet pipe 44 connects first tube outlet 32b of vaporizer 30 to chamber 45. A hydrogen gas temperature sensor 71 that detects hydrogen gas temperature T1 at the outlet of vaporizer 30 is attached to hydrogen gas outlet pipe 44. Chamber 45 stores high-pressure hydrogen gas. Hydrogen gas supply pipe 46 connects chamber 45 to hydrogen gas nozzle 12 of hydrogen engine 10. A pressure reducing valve 47 that reduces the pressure of the hydrogen gas is attached to hydrogen gas supply pipe 46. A pressure sensor 72 and a flow rate sensor 73 are also attached to hydrogen gas supply pipe 46.

[0022] The boil-off line 60 is a flow path that releases boil-off gas vaporized inside the hydrogen tank 41 to the outside of the hydrogen engine vehicle 100. The boil-off line 60 is composed of a boil-off gas port connecting pipe 61, the second tube 33 of the vaporizer 30, a reactor connecting pipe 62, the reactor 63, and an atmosphere release pipe 64. The second tube 33 of the vaporizer 30 is disposed inside the vaporizer 30 and performs heat exchange between the boil-off gas flowing inside and the heat medium flowing on its outer surface, forming a heating flow path that heats the boil-off gas. The boil-off gas port connecting pipe 61 connects the boil-off gas port 41A of the hydrogen tank 41 to the second tube inlet 33a. The reactor connecting pipe 62 connects the second tube outlet 33b to the inlet of the reactor 63. A boil-off gas temperature sensor 75 is attached to the reactor connecting pipe 62 to detect the temperature of the boil-off gas heated by the vaporizer 30. The atmosphere release pipe 64 releases the boil-off gas that has passed through the reactor 63 to the atmosphere. The reactor 63 receives the boil-off gas and air and contains a catalyst 65 that reacts the boil-off gas with oxygen in the air to produce water.

[0023] The control unit 80 is a computer equipped with a CPU 81 for performing information processing therein and a memory 82 for storing control programs and control data. Data detected by the hydrogen gas temperature sensor 71, heat medium temperature sensor 74, boil-off gas temperature sensor 75, pressure sensor 72, and flow rate sensor 73 is input to the control unit 80. The control unit 80 adjusts the operation of the liquid hydrogen pump 42 based on the flow rate data detected by the flow rate sensor 73. The control unit 80 also adjusts the operation of the pressure reducing valve 47 based on the pressure data detected by the pressure sensor 72.

[0024] Furthermore, the control unit 80 adjusts the operation of the heat medium pump 25 based on the hydrogen gas temperature T1 detected by the hydrogen gas temperature sensor 71 and the boil-off gas temperature T3 detected by the boil-off gas temperature sensor 75. Details of this operation will be described later with reference to FIG.

[0025] The control unit 80 also adjusts the operation of the radiator shutoff valve 27 and the bypass valve 28 based on the heat medium temperature T2 detected by the heat medium temperature sensor 74. For example, when the heat medium temperature T2 detected by the heat medium temperature sensor 74 exceeds a predetermined temperature, the control unit 80 closes the radiator shutoff valve 27 and opens the bypass valve 28 to prevent the heat medium from flowing through the radiator heat medium flow path 52, thereby lowering the temperature of the heat medium. Conversely, when the heat medium temperature T2 detected by the heat medium temperature sensor 74 is below the predetermined temperature, the control unit 80 opens the radiator shutoff valve 27 and closes the bypass valve 28 to allow the heat medium to flow through the radiator heat medium flow path 52, thereby raising the temperature of the heat medium. In this way, the control unit 80 adjusts the flow rate of the bypass pipe 26 to adjust the heat medium temperature T2 within a predetermined range.

[0026] The hydrogen engine 10 and the cooling water pump 19 are controlled by an engine control unit (not shown).

[0027] Next, the control of the heat medium pump 25 by the control unit 80 will be described with reference to Fig. 2. As shown in Fig. 2, the control unit 80 includes three control blocks: a temperature feedback control unit 85, a temperature correction value calculation unit 86, and an adder 87. The operation of each control block can be realized by the CPU 81 executing a control program stored in the memory 82.

[0028] The temperature feedback control unit 85 performs feedback control so that the hydrogen gas temperature T1 (actual temperature of hydrogen gas) input from the hydrogen gas temperature sensor 71 becomes the target temperature, and adjusts the duty of the heat transfer medium pump 25. The temperature correction value calculation unit 86 calculates a temperature correction value for correcting the first target temperature, which is the control target temperature of the hydrogen gas, based on the difference between the boil-off gas temperature T3 (actual temperature of boil-off gas) detected by the boil-off gas temperature sensor 75 and the second target temperature, which is the control target temperature of the boil-off gas. The adder 87 adds the temperature correction value to the first target temperature to calculate the target temperature to be input to the temperature feedback control unit 85.

[0029] The flow rate of the boil-off gas flowing through the vaporizer 30 is minute compared to the flow rate of the hydrogen gas flowing through the vaporizer 30. Therefore, if the heat transfer medium pump 25 is feedback-controlled so that the hydrogen gas temperature T1 is within a predetermined temperature range, the boil-off gas temperature T3 will also be within the predetermined temperature range. However, in some cases, the difference between the boil-off gas temperature T3 and the second target temperature becomes large. In such cases, the temperature correction value calculation unit 86 calculates a temperature correction value based on this difference and corrects the first target temperature. This makes it possible to set the boil-off gas temperature T3 to a temperature at which the catalyst 65 can sufficiently react. Furthermore, even if the boil-off gas is heated using the exhaust heat of the hydrogen engine 10, fuel efficiency can be improved compared to conventional techniques in which the boil-off gas is heated using a heater or the like.

[0030] Next, the detailed structure of carburetor 30 will be described with reference to Figures 3 and 4. As shown in Figure 3, carburetor 30 includes a casing 31, a first tube 32, a second tube 33, a hollow longitudinal member 34, an outer tube receiver 35, a middle tube receiver 36, an inner tube receiver 37, and a bracket 38.

[0031] The casing 31 is a cylindrical, longitudinal member having a diameter D1, with a heat transfer medium inlet 31a and a heat transfer medium outlet 31b at both ends. An outer tube support 35 made up of multiple round bars is provided on the inner surface of the casing 31, as shown in Figure 4.

[0032] The first tube 32 is composed of a first inner tube 32i and a first outer tube 32j. The first inner tube 32i is a tube with a diameter d1 wound spirally so that the first outer winding inner diameter is E1, and the first outer winding outer diameter is E2. The first outer tube 32j is a tube with a diameter d1 wound spirally so that the first outer winding outer diameter is F2, and the first outer winding inner diameter is F1. The first inner tube 32i is nested inside the first outer tube 32j, with the first outer winding inner diameter F1. One end of the first inner tube 32i and one end of the first outer tube 32j are connected to each other, and the first inner tube 32i and the first outer tube 32j form a single first tube 32. The other end of the first inner tube 32i forms a first tube inlet 32a into which liquid hydrogen flows. The other end of the first outer tube 32j constitutes a first tube outlet 32b through which vaporized hydrogen gas flows out.

[0033] The hollow longitudinal member 34 is a cylindrical longitudinal member with an outer diameter D2 and is disposed coaxially with the casing 31. Both ends of the hollow longitudinal member 34 are connected to both ends of the casing 31. One end of the hollow longitudinal member 34 is provided with a boil-off gas inlet 34a through which boil-off gas flows in. An inner tube receiver 37 made up of multiple round bars is provided on the outer surface of the hollow longitudinal member 34, as shown in FIG.

[0034] The second tube 33 is formed by spirally winding a tube having a diameter d2 so that the second winding inner diameter is G1, and the second winding outer diameter is G2. One end of the second tube 33 is connected to the hollow longitudinal member 34. The other end of the second tube 33 forms a second tube outlet 33b from which the heated boil-off gas flows out.

[0035] The second winding inner diameter G1 of the second tube 33 is larger than the outer diameter D2 of the hollow longitudinal member 34. The inner winding surface of the second tube 33 is supported by the outer diameter surface of an inner tube receiver 37 provided on the outer surface of the hollow longitudinal member 34. Therefore, the hollow longitudinal member 34 is disposed inside the second winding inner diameter G1 of the second tube 33.

[0036] Furthermore, a plurality of brackets 38 extending radially from the hollow longitudinal member 34 are provided at both ends of the hollow longitudinal member 34. Center tube holders 36, each consisting of a round bar extending in the longitudinal direction, are attached between each bracket 38. The inner wound surface of the first inner tube 32i is supported by the outer diameter surface of the center tube holder 36. The outer wound surface of the first outer tube 32j is supported by the inner diameter surface of an outer tube holder 35 provided in the casing 31. In this manner, the first tube 32 and the second tube 33 are arranged nested one inside the other.

[0037] Liquid hydrogen flows in through the first tube inlet 32a of the first inner tube 32i, and vaporized hydrogen gas flows out through the first tube outlet 32b of the first outer tube 32j. The boil-off gas flows into the hollow longitudinal member 34 through the boil-off gas inlet 34a, flows from one end of the hollow longitudinal member 34 into one end of the second tube 33, and then flows out through the second tube outlet 33b at the other end of the second tube 33. Therefore, the boil-off gas inlet 34a of the hollow longitudinal member 34 constitutes the second tube inlet 33a. The heat transfer medium flows in through the heat transfer medium inlet 31a of the casing 31 and flows through an annular flow path with a width W between the inner surface of the casing 31 and the outer surface of the hollow longitudinal member 34. In this annular flow path, the heat medium exchanges heat with the liquid hydrogen or hydrogen gas flowing in the first tube 32 and also with the boil-off gas flowing in the second tube 33, and then flows out from the heat medium outlet 31b.

[0038] As described above, the vaporizer 30 has the first tube 32 and the second tube 33 nested inside the casing 31, so that it can vaporize liquid hydrogen and heat the boil-off gas with a compact configuration.

[0039] Furthermore, since the heat transfer medium is configured to flow through a circular flow path of width W between the inner surface of the casing 31 and the outer surface of the hollow longitudinal member 34, the flow rate of the heat transfer medium can be increased, resulting in an evaporator 30 with high heat exchange efficiency. [Explanation of symbols]

[0040] 10 hydrogen engine, 11 intake port, 12 hydrogen gas nozzle, 13 exhaust port, 14 internal cooling flow path, 15 cooling water flow path, 16 cooling water supply pipe, 17 cooling water outlet pipe, 18 cooling water return pipe, 19 cooling water pump, 20 heat transfer medium flow path, 21 heat transfer medium supply pipe, 22 heat transfer medium outlet pipe, 23 heat transfer medium return pipe, 25 heat transfer medium pump, 26 bypass pipe, 27 radiator shutoff valve, 28 bypass valve, 30 evaporator, 31 casing, 31a heat transfer medium inlet, 31b heat transfer medium outlet, 32 first tube, 32a first tube inlet, 32b first tube outlet, 32i first inner tube, 32j first outer tube, 33 second tube, 33a second tube inlet, 33b second tube outlet, 34 hollow longitudinal member, 34a boil-off gas inlet, 35 Outer tube receiver, 36 middle tube receiver, 37 inner tube receiver, 38 bracket, 40 hydrogen flow path, 41 hydrogen tank, 41A boil-off gas port, 42 liquid hydrogen pump, 43 liquid hydrogen supply pipe, 44 hydrogen gas outlet pipe, 45 chamber, 46 hydrogen gas supply pipe, 47 pressure reducing valve, 50 radiator, 51 radiator cooling water flow path, 52 radiator heat transfer medium flow path, 60 boil off line, 61 boil-off gas port connecting pipe, 62 reactor connecting pipe, 63 reactor, 64 atmosphere release pipe, 65 catalyst, 71 hydrogen gas temperature sensor, 72 pressure sensor, 73 flow rate sensor, 74 heat transfer medium temperature sensor, 75 boil-off gas temperature sensor, 80 control unit, 81 CPU, 82 memory, 85 temperature feedback control unit, 86 temperature correction value calculation unit, 87 adder, 100 hydrogen engine vehicle.

Claims

[Claim 1] A hydrogen engine, a hydrogen tank for storing liquid hydrogen; a vaporizer that vaporizes the liquid hydrogen using exhaust heat from the hydrogen engine to generate hydrogen gas to be supplied to the hydrogen engine; a boil-off line connected to the hydrogen tank and configured to release boil-off gas vaporized in the hydrogen tank to the outside of the vehicle; The boil-off line is a heating flow path disposed in the vaporizer and configured to heat the boil-off gas flowing therethrough; a catalyst that reacts air with the boil-off gas to produce water; A hydrogen engine vehicle characterized by:

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