Fuel reforming system for vehicle

Abstract

To suppress generation of carbon dioxide in a fuel reforming system mounted to a vehicle.SOLUTION: A fuel reforming system 1 for a vehicle includes: a reciprocal engine 10 mounted to the vehicle; a decomposition device 50 that decomposes hydrocarbon fuel into carbon and hydrogen gas and stores carbon; a hydrocarbon fuel supply section 30 that supplies hydrocarbon fuel to the decomposition device; and a hydrogen gas supply section 40 that supplies hydrogen gas into a cylinder 11. The reciprocal engine executes a cycle including a compression stroke, an expansion stroke and re-compression stroke. The decomposition device decomposes hydrocarbon fuel into carbon and hydrogen gas by using heat and pressure of combustion gas in the re-compression stroke. The decompression device includes: a catalyst 52 to which carbon adheres; and a steam adsorption section to which steam is adsorbed.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a fuel reforming system for a vehicle. [Background technology]

[0002] Patent Document 1 describes a cracking device that directly cracks hydrocarbons into carbon and hydrogen.

[0003] This conventional cracking unit includes a reactor containing a catalyst. When a feed gas containing hydrocarbons is fed into the reactor, carbon adheres to the catalyst, and a reactant gas containing hydrogen passes through the reactor. A hydrogen purification unit located downstream of the reactor purifies the hydrogen in the reactant gas, increasing its concentration. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-104521 Summary of the Invention [Problem to be solved by the invention]

[0005] In the field of vehicle technology (for example, four-wheeled automobiles), efforts to achieve carbon neutrality are being sought. To achieve carbon neutrality in vehicles equipped with engines that use hydrocarbon fuels (including gasoline and / or diesel), new technologies for recovering carbon (C) or carbon dioxide (CO2) from hydrocarbon fuels are required, in addition to improving the thermal efficiency of the engine and / or improving exhaust emission performance.

[0006] In vehicles equipped with engines that use hydrocarbon fuel, carbon or carbon dioxide can be captured by (1) capturing carbon dioxide after the hydrocarbon fuel is combusted, or (2) decomposing the hydrocarbon fuel into carbon and hydrogen gas before combustion and capturing the carbon.

[0007] Considering that the captured carbon dioxide or carbon will be stored in the vehicle, (2) is more advantageous than (1) in terms of vehicle fuel efficiency because carbon dioxide is heavier than carbon (carbon is lighter than carbon dioxide). Also, (2) makes it possible to use hydrogen gas as engine fuel. Combusting hydrogen gas has the advantage of not producing carbon oxides due to combustion.

[0008] Therefore, it is conceivable to mount the above-mentioned conventional disassembly device on a vehicle.

[0009] Conventional cracking equipment includes a fluidized-bed reactor vessel. This reactor vessel contains multiple catalyst particles, and the feed gas is ejected upward from the fluidized bed onto the catalyst particles. Carbon adhering to the catalyst particles is removed by suspending the catalyst particles in the feed gas and rubbing the catalyst particles against each other.

[0010] Furthermore, conventional cracking apparatuses are equipped with a catalyst regenerator outside the reactor. The catalyst regenerator is connected to the reactor via a catalyst supply line and a catalyst return line. The catalyst regenerator removes carbon from catalyst particles supplied from the reactor via the catalyst supply line and returns the decarbonized catalyst particles to the reactor via the catalyst return line.

[0011] Catalyst regeneration devices include, for example, rotary pipes that remove carbon from catalyst particles by stirring them and rubbing them against each other, catalyst dissolution devices that remove carbon from catalyst particles by dissolving them, and catalyst conversion devices that remove carbon from catalyst particles by converting the carbon into methane, carbon monoxide, or carbon dioxide using hydrogen, water vapor, and oxygen.

[0012] Conventional cracking devices have the above-mentioned fluidized bed or catalyst regeneration device as a carbon removal mechanism for removing carbon from the catalyst, which inevitably leads to a large and complicated configuration. Furthermore, conventional cracking devices require a heating device to heat the catalyst. For this reason, it is difficult to install conventional cracking devices on vehicles.

[0013] Even if it were possible to install a cracking device on a vehicle, there is a concern that carbon dioxide would be generated in the cracking device due to the steam reforming reaction and the accompanying water gas shift reaction caused by the water vapor in the combustion gas.

[0014] An object of the present disclosure is to suppress the generation of carbon dioxide in a fuel reforming system mounted on a vehicle. [Means for solving the problem]

[0015] A fuel reforming system for a vehicle according to the present disclosure includes a reciprocating engine mounted on a vehicle and having a piston reciprocating within a cylinder, a cracker that decomposes hydrocarbon fuel into carbon and hydrogen gas and stores the carbon, a hydrocarbon fuel supply unit that supplies the hydrocarbon fuel to the cracker, and a hydrogen gas supply unit that supplies the hydrogen gas produced by the cracker into the cylinder, wherein the reciprocating engine executes a cycle that includes at least a compression stroke in which an air-fuel mixture containing the hydrogen gas in the cylinder is compressed as the piston rises, an expansion stroke in which the piston descends as the air-fuel mixture is combusted, and a recompression stroke in which combustion gas is compressed as the piston rises, and the cracker uses the heat and pressure of the combustion gas in the recompression stroke to decompose the hydrocarbon fuel supplied from the hydrocarbon fuel supply unit into the carbon and the hydrogen gas, and the cracker has a catalyst to which the carbon adheres and a water vapor adsorption unit to which water vapor is adsorbed.

[0016] A reciprocating engine includes a compression stroke, an expansion stroke, and then a recompression stroke in which the combustion gases are compressed by the rising piston. A hydrocarbon fuel supply supplies hydrocarbon fuel to the cracker.

[0017] The cracker utilizes the heat and pressure of the combustion gases from the recompression process to decompose the hydrocarbon fuel into carbon and hydrogen gas. The cracker can efficiently decompose the hydrocarbon fuel. The carbon is stored in the cracker.

[0018] The hydrogen gas supply unit supplies the hydrogen gas produced in the cracker as fuel into the cylinders of the reciprocating engine. The reciprocating engine operates by burning the hydrogen gas. No carbon oxides are produced by combustion. The reciprocating engine can supply heat and pressure to the cracker for cracking hydrocarbon fuel while outputting driving power to run the vehicle.

[0019] The fuel reforming system can achieve carbon neutrality. Because the fuel reforming system utilizes the heat and pressure generated by the reciprocating engine, a separate dedicated device is not required to generate the heat and / or pressure required to decompose hydrocarbon fuel. The fuel reforming system is useful as an on-board system installed in a vehicle.

[0020] The cracker further includes a catalyst to which carbon adheres and a water vapor adsorption section to which water vapor is adsorbed. Here, water vapor may be mixed in the combustion gas supplied to the cracker.

[0021] In the cracker, the water vapor is adsorbed by the water vapor adsorption section, which prevents the water vapor from being adsorbed by the catalyst. This suppresses the steam reforming reaction and the accompanying water gas shift reaction in the cracker, making it difficult for carbon dioxide to be generated.

[0022] As described above, the generation of carbon dioxide can be suppressed in the fuel reforming system 1 mounted on a vehicle.

[0023] In one embodiment, the water vapor adsorption portion is made of a material that generates heat when the water vapor is adsorbed thereon.

[0024] According to this configuration, the heat generated when the water vapor is adsorbed by the water vapor adsorption section can promote the decomposition reaction that decomposes the hydrocarbon fuel into carbon and hydrogen gas.

[0025] In one embodiment, the water vapor adsorption section is disposed adjacent to the catalyst.

[0026] According to this configuration, it is possible to encourage the water vapor to be adsorbed not by the catalyst but by the adjacent water vapor adsorption section.

[0027] In one embodiment, the decomposition vessel has a support, and a surface of the support has adjacent recesses and protrusions, one of the recesses and the protrusions supports the catalyst, and the other of the recesses and the protrusions has the water vapor adsorption section disposed thereon.

[0028] According to this configuration, by providing a step between the catalyst and the water vapor adsorption section, the water vapor can be separated from the catalyst and the adsorption of water vapor to the water vapor adsorption section can be further promoted, thereby further promoting the adhesion of carbon to the catalyst.

[0029] In one embodiment, the support is cylindrical and supports the catalyst on its inner surface as the surface, the recesses and protrusions are provided on the inner surface, and the water vapor adsorption portion is located inside the catalyst.

[0030] With this configuration, the water vapor adsorption section comes into contact with water vapor before the catalyst comes into contact with water vapor, which allows the water vapor to be adsorbed by the water vapor adsorption section before it is adsorbed by the catalyst.

[0031] In one embodiment, the support constitutes the water vapor adsorption portion, the protrusions being exposed as the water vapor adsorption portion, and the recesses being covered with the catalyst.

[0032] According to this configuration, it becomes easy to arrange the catalyst and the water vapor adsorption portion on the surface of the support. [Effects of the Invention]

[0033] According to the present disclosure, it is possible to suppress the generation of carbon dioxide in a fuel reforming system mounted on a vehicle. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 shows a fuel reforming system. [Figure 2] FIG. 2 is a front cross-sectional view of the decomposer and carbon recovery unit according to the first embodiment. [Figure 3] FIG. 3 shows a side cross-sectional view of the decomposer according to the first embodiment. [Figure 4] FIG. 4 shows the hydrogen gas supply section. [Figure 5] Figure 5 shows the control system. [Figure 6] FIG. 6 shows each step of a six-stroke cycle according to the first embodiment. [Figure 7] FIG. 7 is a schematic diagram showing the inner surface of the support in the decomposer according to the first embodiment. [Figure 8] FIG. 8 is a schematic diagram showing the inner surface of the support in the decomposer according to the second embodiment. [Figure 9] FIG. 9 is a front cross-sectional view of a decomposer according to a third embodiment. [Figure 10] FIG. 10 shows each stroke of a modified four-stroke cycle according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0036] First Embodiment (Fuel reforming system) A fuel reforming system 1 for a vehicle according to a first embodiment will be described. FIG. 1 shows the fuel reforming system 1. The fuel reforming system 1 is mounted on a vehicle. The vehicle may be, for example, a four-wheeled vehicle or a two-wheeled vehicle. The fuel reforming system 1 decomposes hydrocarbon fuel (CH fuel) into carbon (C) and hydrogen gas (H gas) using a decomposer 50, which will be described later. The carbon is stored in the decomposer 50. The hydrogen gas is used as fuel for a reciprocating engine 10. The fuel reforming system 1 makes the vehicle carbon neutral.

[0037] The vehicle fuel reforming system 1 includes a reciprocating engine 10, a hydrocarbon fuel supply unit 30, a hydrogen gas supply unit 40, a cracker 50, a carbon recovery unit 70, a control system 80, and a hydrogen gas passage 90.

[0038] (reciprocating engine) The reciprocating engine 10 is mounted on a vehicle and includes a cylinder 11, a piston 12, an intake port 13, an intake valve 14, an exhaust port 15, an exhaust valve 16, a reforming port 17, and an on-off valve 18.

[0039] There are multiple cylinders 11. The multiple cylinders 11 are lined up, for example, in the direction in which the crankshaft of the reciprocating engine 10 extends. A piston 12 is housed in each cylinder 11. The piston 12 reciprocates within the cylinder 11. The piston 12 is connected to the crankshaft via a connecting rod. The connecting rod converts the reciprocating motion of the piston 12 into rotation of the crankshaft. The crankshaft is connected to the drive wheels via a transmission. The reciprocating engine 10 outputs driving force for running the vehicle. The reciprocating engine 10 may also be used as a driving source for driving a generator.

[0040] The intake ports 13 communicate with the cylinders 11. One or more intake ports 13 are connected to each cylinder 11. For example, two intake ports 13 are connected to each cylinder 11. The intake ports 13 are connected to an intake pipe. Intake air is introduced into the cylinders 11 through the intake ports 13. The intake air includes fresh air. The intake air may also include EGR (Exhaust Gas Recirculation) gas. The intake valves 14 are poppet valves that open and close the intake ports 13. When the intake valves 14 open, the intake air is introduced into the cylinders 11 through the intake ports 13.

[0041] The exhaust port 15 communicates with the cylinder 11. One or more exhaust ports 15 are connected to each cylinder 11. For example, one exhaust port 15 may be connected to each cylinder 11. The exhaust port 15 is connected to an exhaust pipe. Exhaust gas is discharged from inside the cylinder 11 to outside the cylinder 11 through the exhaust port 15. The exhaust valve 16 is a poppet valve that opens and closes the exhaust port 15. When the exhaust valve 16 opens, exhaust gas is discharged from inside the cylinder 11 to outside the cylinder 11 through the exhaust port 15.

[0042] The reforming port 17 is in communication with the cylinder 11. At least one reforming port 17 is connected to each cylinder 11. For example, one reforming port 17 may be connected to each cylinder 11. The on-off valve 18 is a poppet valve and opens and closes the reforming port 17.

[0043] A typical reciprocating engine has two intake ports and two exhaust ports per cylinder. One of the two exhaust ports may be converted into a reforming port 17. Alternatively, one of the two intake ports may be converted into a reforming port 17. In this example, the reciprocating engine 10 has two intake ports 13, one exhaust port 15, and one reforming port 17 per cylinder 11. Note that in FIG. 1, the exhaust port 15 and the reforming port 17 are depicted at offset positions for ease of understanding.

[0044] The reciprocating engine 10 has an intake valve train 21, an exhaust valve train 22, and a reforming valve train 23 (see FIG. 5). The intake valve train 21 opens and closes the intake valve 14. The exhaust valve train 22 opens and closes the exhaust valve 16. The reforming valve train 23 opens and closes the on-off valve 18.

[0045] The intake valve train 21 and the exhaust valve train 22 have intake camshafts and exhaust camshafts mechanically connected to the intake valve 14 and the exhaust valve 16, and can continuously change the valve timing of the intake valve 14 and the exhaust valve 16 (so-called S-VT (Sequential-Valve Timing)). The intake valve train 21 and the exhaust valve train 22 can continuously change the valve lift of the intake valve 14 and the exhaust valve 16 (so-called CVVL (Continuously Variable Valve Lift)). The intake valve train 21 and the exhaust valve train 22 can employ known hydraulic or electric mechanisms.

[0046] The reforming valve train 23 has, for example, a reforming camshaft mechanically connected to the on-off valve 18. The reforming valve train 23 opens the on-off valve 18 twice during one cycle (see FIG. 6). The reforming valve train 23 can stop the on-off valve 18 from opening or closing. A known hydraulic or electric mechanism can be used as a valve stop mechanism that stops the on-off valve 18 from opening or closing. The valve stop mechanism may be incorporated, for example, into a rocker arm interposed between the reforming camshaft and the on-off valve 18. The valve stop mechanism may be incorporated into a lash adjuster that supports the rocker arm. The on-off valve 18 may be mechanically connected to the intake camshaft or the exhaust camshaft.

[0047] The reciprocating engine 10 has an intake port injector 24, a reforming port injector 25, and a hydrogen injector 26. The injection holes of the intake port injector 24 face into the intake port 13. The intake port injector 24 injects hydrocarbon fuel into the intake port 13. The injection holes of the reforming port injector 25 face into the reforming port 17. The reforming port injector 25 injects hydrocarbon fuel into the reforming port 17. The injection holes of the hydrogen injector 26 face into the cylinder 11. The hydrogen injector 26 injects hydrogen gas into the cylinder 11.

[0048] It should be noted that an injector that injects hydrocarbon fuel may face the inside of the cylinder 11 , and a hydrogen injector that injects hydrogen gas may face the inside of the intake port 13 .

[0049] The reciprocating engine 10 has a spark plug 27 (see FIG. 5). The spark plug 27 faces the inside of the cylinder 11. The spark plug 27 ignites the air-fuel mixture in the cylinder 11.

[0050] (Hydrocarbon fuel supply unit and hydrogen gas supply unit) The hydrocarbon fuel supply unit 30 is mounted on the vehicle. The hydrocarbon fuel supply unit 30 is connected to the intake port injector 24. The hydrocarbon fuel supply unit 30 is also connected to the reforming port injector 25. The hydrocarbon fuel supply unit 30 selectively supplies hydrocarbon fuel to the intake port injector 24 and the reforming port injector 25.

[0051] The hydrocarbon fuel supply unit 30 has a fuel tank that stores hydrocarbon fuel and a fuel pump that pumps the hydrocarbon fuel. The hydrocarbon fuel is stored in the fuel tank. The hydrocarbon fuel is, for example, gasoline. The hydrocarbon fuel may also be diesel fuel. The hydrocarbon fuel may also be other fuels.

[0052] As described above, the hydrocarbon fuel supply unit 30 supplies hydrocarbon fuel to the reforming port injector 25. The reforming port injector 25 supplies hydrocarbon fuel into the reforming port 17. The hydrocarbon fuel supplied into the reforming port 17 is supplied to the cracker 50, which will be described later. In summary, the hydrocarbon fuel supply unit 30 supplies hydrocarbon fuel to the cracker 50 through the reforming port injector 25 and the reforming port 17.

[0053] The hydrogen gas supply unit 40 is mounted on the vehicle. The hydrogen gas supply unit 40 is connected to the hydrogen injector 26. The hydrogen gas supply unit 40 supplies hydrogen gas to the hydrogen injector 26. As described above, the hydrogen gas is hydrogen gas decomposed from a hydrocarbon fuel. The configuration of the hydrogen gas supply unit 40 will be described later.

[0054] (decomposer) The cracker 50 is mounted on the vehicle. The cracker 50 is connected to the reforming port 17. The cracker 50 is attached to each cylinder 11. The cracker 50 may be common to multiple cylinders 11. The cracker 50 is a so-called membrane reactor.

[0055] Fig. 2 is a front cross-sectional view of cracker 50. Fig. 3 is a side cross-sectional view of cracker 50 taken along line III. Cracker 50 has a support 51, a catalyst 52, a hydrogen separation membrane 53, a case 54, and a water vapor adsorption section 55.

[0056] The support 51 is formed in a cylindrical shape. The cylindrical support 51 includes an outer surface 51a facing the outer periphery and an inner surface 51b facing the inner periphery. The support 51 is made of, for example, ceramic. The support 51 may be made of, for example, aluminum oxide. The support 51 may be made of other materials. The catalyst 52 is supported on the inner surface 51b of the cylindrical support 51. In other words, the cylindrical support 51 supports the catalyst 52 on the inner surface 51b. Specifically, the catalyst 52 is applied to a part or all of the inner surface 51b of the cylindrical support 51.

[0057] Carbon from the hydrocarbon fuel adheres to the catalyst 52. The catalyst 52 is made of, for example, a Ni-Al-Fe alloy. Note that various catalysts can be used as the catalyst 52 as long as they can adhere carbon. Carbon adheres to the catalyst 52 through a chemical reaction.

[0058] The hydrogen separation membrane 53 is formed in a cylindrical shape. The cylindrical hydrogen separation membrane 53 includes an outer surface 53a facing the outer periphery and an inner surface 53b facing the inner periphery. The hydrogen separation membrane 53 is disposed inside the support 51 (inside the inner surface 51b of the support 51). The outer diameter of the hydrogen separation membrane 53 is smaller than the inner diameter of the support 51. A gap A is formed between the inner surface 51b of the support 51 and the outer surface 53a of the hydrogen separation membrane 53. Of the hydrocarbon fuels, only hydrogen gas permeates the hydrogen separation membrane 53. The hydrogen separation membrane 53 is made of, for example, a Pd alloy. However, the hydrogen separation membrane 53 is not limited to a Pd alloy membrane.

[0059] Hereinafter, the right side of FIG. 2 will be referred to as one side, and the left side of FIG. 2 will be referred to as the other side. The direction from one side to the other side is the horizontal direction. The upper side of FIG. 2 will be simply referred to as the upper side, and the lower side of FIG. 2 will be simply referred to as the lower side. One end of the support 51 is open. One end of the support 51 is connected to (communicates with) the reforming port 17. The opening at one end of the support 51 faces the reforming port 17. The other end of the support 51 is open. The other end of the support 51 is connected to (communicates with) the carbon recovery section 70 described below. The opening at the other end of the support 51 faces the carbon recovery section 70.

[0060] One end of the hydrogen separation membrane 53 is closed. One end of the hydrogen separation membrane 53 is recessed toward the other side from one end of the support 51. The other end of the hydrogen separation membrane 53 protrudes toward the other side from the other end of the support 51. The other end of the hydrogen separation membrane 53 is open. The other end of the hydrogen separation membrane 53 is connected (communicates) with a cylindrical hydrogen gas passage 90. The outer diameter of the other end of the hydrogen separation membrane 53 fits into the inner diameter of one end of the hydrogen gas passage 90. The opening at the other end of the hydrogen separation membrane 53 faces the hydrogen gas passage 90.

[0061] The hydrogen gas passage 90 connects the hydrogen separation membrane 53 and the hydrogen injector 26. A hydrogen gas supply unit 40, which will be described later, is connected to the middle of the hydrogen gas passage 90 (see FIG. 4).

[0062] The case 54 is formed in a substantially cylindrical shape. The case 54 includes a cylindrical tubular portion 54a and inward extending portions 54b extending inward from one end and the other end of the tubular portion 54a. The tubular portion 54a of the case 54 covers the outer surface 51a of the support 51. The inward extending portions 54b of the case 54 cover one end face and the other end face of the support 51. The case 54 holds the support 51 and the hydrogen separation membrane 53.

[0063] The hydrocarbon fuel is introduced into the support 51 (inside the inner surface 51b) from an opening at one end of the support 51 through the reforming port 17 together with combustion gas, which will be described later (see the black arrow in FIG. 2). The hydrocarbon fuel flows from one side to the other through a gap A between the inner surface 51b of the support 51 and the outer surface 53a of the hydrogen separation membrane 53.

[0064] Of the hydrocarbon fuel flowing through gap A, carbon adheres to catalyst 52 on inner surface 51b of support 51. Of the hydrocarbon fuel flowing through gap A, hydrogen gas passes through hydrogen separation membrane 53 from the outside to the inside and is introduced inside hydrogen separation membrane 53 (inside inner surface 53b) (see the outline arrow in FIG. 2). The hydrogen gas flows inside hydrogen separation membrane 53 (inside inner surface 53b) to the other side and is supplied to hydrogen gas supply unit 40, which will be described later, through hydrogen gas passage 90.

[0065] Hydrocarbon fuel is supplied from the hydrocarbon fuel supply unit 30 to the cracker 50 via the reforming port injector 25 and the reforming port 17. The cracker 50 decomposes the hydrocarbon fuel into carbon and hydrogen gas by causing the carbon to adhere to the catalyst 52 and the hydrogen gas to pass through the hydrogen separation membrane 53. The cracker 50 generates carbon and hydrogen gas, which are decomposed from each other.

[0066] The cracker 50 stores carbon. Specifically, the carbon attached to the catalyst 52 on the inner surface 51b of the support 51 remains in the gap A between the inner surface 51b of the support 51 and the outer surface 53a of the hydrogen separation membrane 53.

[0067] The decomposition of hydrocarbon fuels, for example the decomposition of isooctane, is represented by the following chemical reaction: iC8H18(g)=8C(s)+9H2.

[0068] The water vapor adsorption section 55 will be described later.

[0069] (Hydrogen gas supply unit) 4 shows the hydrogen gas supply unit 40. Hereinafter, the upstream side in the flow of hydrogen gas (decomposer 50 side) will be simply referred to as the upstream side, and the downstream side in the flow of hydrogen gas (hydrogen injector 26 side) will be simply referred to as the downstream side.

[0070] The hydrogen gas supply unit 40 is mounted on a vehicle. The hydrogen gas supply unit 40 is provided midway through a hydrogen gas passage 90. The upstream end of the hydrogen gas passage 90 is connected to a cracker 50. As described above, the cracker 50 generates hydrogen gas. The downstream end of the hydrogen gas passage 90 is connected to a hydrogen injector 26. Hydrogen gas is supplied to the hydrogen gas supply unit 40 from the cracker 50. The hydrogen gas supply unit 40 supplies the hydrogen gas to the hydrogen injector 26. The hydrogen injector 26 injects the hydrogen gas into the cylinder 11.

[0071] In summary, the hydrogen gas supply unit 40 supplies the hydrogen gas produced by the cracker 50 into the cylinder 11 through the hydrogen gas passage 90 and the hydrogen injector 26 .

[0072] The hydrogen gas supply unit 40 may be common to multiple cylinders 11. Alternatively, a hydrogen gas supply unit 40 may be provided for each cylinder 11. The hydrogen gas supply unit 40 includes a first tank 41, a second tank 42, a bypass passage 43, a first switching valve 44, a second switching valve 45, and a hydrogen pump 46.

[0073] The first tank 41 is connected to the hydrogen gas passage 90. The first tank 41 stores the hydrogen gas supplied from the cracker 50.

[0074] The bypass passage 43 is configured as a part of the hydrogen gas passage 90, and bypasses the first tank 41. The first switching valve 44 is connected to the hydrogen gas passage 90 upstream of the first tank 41. The second switching valve 45 is connected to the hydrogen gas passage 90 downstream of the first tank 41. The first switching valve 44 and the second switching valve 45 receive control signals from a controller 81, which will be described later, and switch the hydrogen gas flow path between the first tank 41 side and the bypass passage 43 side.

[0075] The hydrogen pump 46 is connected to the hydrogen gas passage 90 downstream of the second switching valve 45. The hydrogen pump 46 increases the pressure of the hydrogen gas. The second tank 42 is connected to the hydrogen gas passage 90 below the hydrogen pump 46. The second tank 42 is located in the hydrogen gas passage 90 between the hydrogen pump 46 and the hydrogen injector 26. The second tank 42 stores high-pressure hydrogen gas.

[0076] The pressure of the first tank 41 is lower than the pressure of the second tank 42. The low-pressure first tank 41 lowers the pressure on the secondary side of the hydrogen separation membrane 53 (the pressure inside the inner surface 53b of the hydrogen separation membrane 53) below the pressure on the primary side of the hydrogen separation membrane 53 (the pressure in the gap A between the inner surface 51b of the support 51 and the outer surface 53a of the hydrogen separation membrane 53). The low-pressure first tank 41 increases the pressure difference between the primary and secondary sides of the hydrogen separation membrane 53. The large pressure difference promotes permeation of hydrogen gas through the hydrogen separation membrane 53. The hydrogen gas generated in the gap A (primary side) between the inner surface 51b of the support 51 and the outer surface 53a of the hydrogen separation membrane 53 quickly permeates inside the inner surface 53b of the hydrogen separation membrane 53 (secondary side), thereby promoting the cracking reaction of the hydrocarbon fuel in the cracker 50.

[0077] The combination of the first tank 41 and the heat and pressure of the combustion gas in the recompression stroke S4, which will be described later, significantly accelerates the cracking reaction of the hydrocarbon fuel in the cracker 50. Acceleration of the cracking reaction of the hydrocarbon fuel makes it possible to ensure the amount of hydrogen gas necessary to operate the reciprocating engine 10, even if the cracker 50 is small.

[0078] Similarly, when the hydrogen gas flow path is switched to the bypass passage 43 side, the pressure on the secondary side of the hydrogen separation membrane 53 decreases due to the operation of the hydrogen pump 46. The high-pressure second tank 42 can stably supply high-pressure hydrogen gas to the hydrogen injector 26. The hydrogen injector 26 can inject hydrogen gas into the cylinder 11 at a timing near the compression top dead center when the pressure inside the cylinder 11 is high. The hydrogen pump 46 makes it possible to supply high-pressure hydrogen gas to the hydrogen injector 26 while maintaining a low pressure in the first tank 41.

[0079] (Carbon Recovery Department) 2 is a front cross-sectional view of the carbon recovery unit 70. The carbon recovery unit 70 is mounted on a vehicle. The carbon recovery unit 70 has a housing 71, a discharge passage 72, and a discharge valve 73.

[0080] The housing 71 includes a cylindrical portion 71a and a lid portion 71b. The cylindrical portion 71a is cylindrical. One end of the cylindrical portion 71a of the housing 71 is connected to the other end of the support 51 via the inner extension portion 54b of the case 54. The other end of the hydrogen separation membrane 53 and one end of a hydrogen gas passage 90 are housed inside the cylindrical portion 71a of the housing 71. A discharge hole 74 is formed in the lower portion of the cylindrical portion 71a of the housing 71. The lid portion 71b of the housing 71 covers the opening at the other end of the cylindrical portion 71a. A through-hole is formed in the lid portion 71b of the housing 71. The hydrogen gas passage 90 passes through the through-hole in the lid portion 71b of the housing 71.

[0081] The discharge path 72 includes a cylindrical portion 72a and a lid portion 72b. The cylindrical portion 72a of the discharge path 72 is cylindrical and extends vertically. The upper end of the cylindrical portion 72a of the discharge path 72 is connected to a discharge hole 74 provided in the lower part of the cylindrical portion 71a of the housing 71. In the discharge path 72, the lid portion 72b covers the lower end of the cylindrical portion 72a. Carbon removed from the catalyst 52 of the cracker 50 is discharged into the discharge path 72. The carbon discharged into the discharge path 72 is accumulated in the discharge path 72.

[0082] The discharge valve 73 opens and closes the discharge path 72. More specifically, the discharge valve 73 opens and closes a discharge hole 74 (a connection between the housing 71 and the discharge path 72) at the bottom of the cylindrical portion 71a of the housing 71. When the discharge valve 73 closes the discharge path 72, the internal space of the discharge path 72 does not communicate with the internal space of the housing 71. When the discharge valve 73 opens the discharge path 72, the internal space of the discharge path 72 communicates with the internal space of the housing 71.

[0083] The carbon recovery unit 70 recovers the carbon generated in the decomposer 50. In particular, the carbon recovery unit 70 recovers the carbon removed from the catalyst 52 of the decomposer 50. The carbon discharged into the discharge path 72 of the carbon recovery unit 70 is removed from the vehicle, for example, when the vehicle is brought in for maintenance. The removed carbon can be reused as a recycled product.

[0084] (Control System) 5 is a block diagram of a control system 80. The control system 80 includes a controller 81. The controller 81 is made up of hardware such as a processor, memory, and interface, and software such as a database and control program.

[0085] The rotation speed sensor 82 is electrically connected to the controller 81. The rotation speed sensor 82 is attached to the reciprocating engine 10. The rotation speed sensor 82 outputs a measurement signal corresponding to the rotation speed of the crankshaft to the controller 81. The controller 81 can grasp the rotation speed of the reciprocating engine 10 based on the measurement signal of the rotation speed sensor 82.

[0086] An accelerator position sensor 83 is electrically connected to the controller 81. The accelerator position sensor 83 is attached to the accelerator pedal. The accelerator position sensor 83 outputs a signal corresponding to the depression amount of the accelerator pedal to the controller 81. The controller 81 can grasp the required load of the reciprocating engine 10 based on the measurement signal of the accelerator position sensor 83.

[0087] The knock sensor 84 is electrically connected to the controller 81. The knock sensor 84 is attached to the reciprocating engine 10. When knocking occurs in the reciprocating engine 10, the knock sensor 84 outputs a knock detection signal to the controller 81. The controller 81 can determine the occurrence of knocking based on the knock detection signal.

[0088] A tank pressure sensor 85 is electrically connected to the controller 81. The tank pressure sensor 85 is attached to the second tank 42 of the hydrogen gas supply unit 40. The tank pressure sensor 85 outputs a signal corresponding to the amount of hydrogen gas in the second tank 42 to the controller 81. The controller 81 can determine the amount of hydrogen gas that can be supplied to the cylinder 11 based on the signal from the tank pressure sensor 85.

[0089] The intake valve train 21, the exhaust valve train 22, and the reforming valve train 23 are electrically connected to a controller 81. The controller 81 outputs control signals to the intake valve train 21, the exhaust valve train 22, and the reforming valve train 23 depending on the operating state of the reciprocating engine 10. The intake valve train 21 changes the valve timing and / or valve lift of the intake valve 14 based on the control signal from the controller 81. The exhaust valve train 22 changes the valve timing and / or valve lift of the exhaust valve 16 based on the control signal from the controller 81. The reforming valve train 23 switches the on-off valve 18 between open and closed states based on the control signal from the controller 81.

[0090] The intake port injector 24, the reforming port injector 25, and the hydrogen injector 26 are electrically connected to a controller 81. The controller 81 outputs control signals to the intake port injector 24, the reforming port injector 25, and the hydrogen injector 26. The intake port injector 24 injects a predetermined amount of hydrocarbon fuel into the intake port 13 at a predetermined timing based on the control signal from the controller 81. The reforming port injector 25 injects a predetermined amount of hydrocarbon fuel into the reforming port 17 at a predetermined timing based on the control signal from the controller 81. The hydrogen injector 26 injects a predetermined amount of hydrogen gas into the cylinder 11 at a predetermined timing based on the control signal from the controller 81.

[0091] The spark plug 27 is electrically connected to the controller 81. The spark plug 27 is attached to the reciprocating engine 10. The controller 81 outputs a control signal to the spark plug 27. Based on the control signal from the controller 81, the spark plug 27 ignites the air-fuel mixture in the cylinder 11 at a predetermined timing.

[0092] The hydrogen gas supply unit 40 is electrically connected to a controller 81. The controller 81 outputs control signals to the first switching valve 44, the second switching valve 45 and the hydrogen pump 46 in the hydrogen gas supply unit 40.

[0093] The discharge valve 73 of the carbon recovery unit 70 is electrically connected to the controller 81. The controller 81 outputs a control signal to the discharge valve 73 of the carbon recovery unit 70. The discharge valve 73 of the carbon recovery unit 70 opens and closes the discharge path 72 of the carbon recovery unit 70 based on the control signal from the controller 81.

[0094] (6-stroke cycle) The reciprocating engine 10 executes a six-stroke cycle in order for the cracker 50 to crack hydrocarbon fuel. Figure 6 shows each stroke of the six-stroke cycle. The six-stroke cycle includes an intake stroke S1, a compression stroke S2, an expansion stroke S3, a recompression stroke S4, a re-expansion stroke S5, and an exhaust stroke S6.

[0095] During the intake stroke S1, intake air is introduced into the cylinder 11 as the piston 12 descends. During the intake stroke S1, the intake valve 14 opens. The intake air is introduced into the cylinder 11 through the intake port 13. The intake air includes fresh air. The intake air may also include EGR gas. This EGR gas is external EGR gas that has been recirculated to the intake pipe through the EGR passage. During the intake stroke S1, the exhaust valve 16 may open. When the exhaust valve 16 opens, exhaust gas is introduced into the cylinder 11 through the exhaust port 15. The exhaust gas introduced into the cylinder 11 is internal EGR gas. The opening / closing valve 18 of the reforming port 17 is closed.

[0096] The hydrogen injector 26 (hydrogen gas supply unit 40) injects (supplies) hydrogen gas into the cylinder 11 during the intake stroke S1. The hydrogen injector 26 may inject hydrogen gas during the compression stroke S2 ​​following the intake stroke S1. The hydrogen injector 26 may inject hydrogen gas during the period from the intake stroke S1 to the compression stroke S2. A mixture of hydrogen gas and intake air is generated in the cylinder 11.

[0097] If there is a shortage of hydrogen gas, the intake port injector 24 may inject hydrocarbon fuel into the intake port 13 during the intake stroke S1 to make up for the shortage. If there is no hydrogen gas, the intake port injector 24 may inject hydrocarbon fuel into the intake port 13 during the intake stroke S1 instead of the hydrogen injector 26. If there is a shortage of hydrogen gas to be supplied into the cylinder 11, the intake port injector 24 injects hydrocarbon fuel, thereby ensuring the required fuel amount for the reciprocating engine 10. The reciprocating engine 10 can be operated using hydrocarbon fuel or both hydrocarbon fuel and hydrogen gas.

[0098] In the compression stroke S2, the air-fuel mixture containing hydrogen gas in the cylinder 11 is compressed by the upward movement of the piston 12. In the compression stroke S2, the intake valve 14, the exhaust valve 16, and the on-off valve 18 are all closed.

[0099] The spark plug 27 ignites the air-fuel mixture in the cylinder 11 near the top dead center of the compression stroke. The air-fuel mixture begins to burn. During the expansion stroke S3, the piston 12 descends due to the combustion of the air-fuel mixture. During the expansion stroke S3, the intake valve 14, exhaust valve 16, and on-off valve 18 are all closed.

[0100] In the recompression stroke S4, the piston 12 rises, compressing the combustion gas in the cylinder 11. In the recompression stroke S4, the on-off valve 18 opens. In the recompression stroke S4, the compressed combustion gas is introduced into the cracker 50 through the reforming port 17. In the recompression stroke S4, the reforming port injector 25 injects hydrocarbon fuel into the reforming port 17. The hydrocarbon fuel is introduced into the cracker 50 together with the combustion gas. In detail, in the recompression stroke S4, the hydrocarbon fuel is supplied from the hydrocarbon fuel supply unit 30 to the cracker 50 via the reforming port injector 25 and the reforming port 17, and the combustion gas is supplied from inside the cylinder 11 to the cracker 50 via the reforming port 17.

[0101] In the recompression step S4, the hydrocarbon fuel is decomposed into carbon and hydrogen gas in the cracker 50 by the heat of the combustion gas and the catalyst 52. The carbon adheres to the catalyst 52 and is stored in the cracker 50. In the recompression step S4, the hydrogen gas permeates the hydrogen separation membrane 53 in the cracker 50 due to the pressure of the combustion gas and is sent to the hydrogen gas supply unit 40 via the hydrogen gas passage 90.

[0102] Since the high pressure of the combustion gas in the recompression step S4 is applied to the cracker 50 (more specifically, the gap A between the inner surface 51b of the support 51 and the outer surface 53a of the hydrogen separation membrane 53), the hydrogen gas generated in the cracker 50 (gap A) quickly permeates the hydrogen separation membrane 53 and is sent to the inside of the hydrogen separation membrane 53 (more specifically, inside the inner surface 53b of the hydrogen separation membrane 53).

[0103] In this way, the cracker 50 uses the heat and pressure of the combustion gas in the recompression stroke S4 to crack the hydrocarbon fuel supplied from the hydrocarbon fuel supply unit 30 (via the reforming port injector 25 and the reforming port 17) into carbon and hydrogen gas. This promotes the cracking reaction of the hydrocarbon fuel in the cracker 50. The cracker 50, which uses the heat and pressure in the recompression stroke S4 of the reciprocating engine 10, can generate the amount of hydrogen gas necessary to operate the reciprocating engine 10 even though it is small in size.

[0104] In the re-expansion stroke S5, the piston 12 descends. In the re-expansion stroke S5, the on-off valve 18 may be opened. When the on-off valve 18 is opened, the combustion gas from which carbon and hydrogen gas have been removed is introduced from the cracker 50 into the cylinder 11 via the reforming port 17. Opening the on-off valve 18 in the re-expansion stroke S5 is advantageous in reducing pumping losses in the reciprocating engine 10.

[0105] During the exhaust stroke S6, the combustion gas in the cylinder 11 is discharged through the exhaust port 15 as the piston 12 rises. During the exhaust stroke S6, the exhaust valve 16 opens. Note that during the exhaust stroke S6, the intake valve 14 and the on-off valve 18 are closed.

[0106] After the exhaust stroke S6, the reciprocating engine 10 returns to the intake stroke S1.

[0107] Instead of opening the on-off valve 18 in the re-expansion stroke S5, or in conjunction with opening the on-off valve 18 in the re-expansion stroke S5, the on-off valve 18 may be opened in the intake stroke S1. When the on-off valve 18 opens in the intake stroke S1, the combustion gas from which carbon and hydrogen gas have been removed is introduced from the cracker 50 into the cylinder 11 via the reforming port 17. This combustion gas becomes EGR gas.

[0108] If the on-off valve 18 is closed in the re-expansion stroke S5, the hydrocarbon fuel introduced into the cracker 50 in the re-compression stroke S4 will remain in the cracker 50 for a long time, which has the advantage of promoting the cracking reaction of the hydrocarbon fuel.

[0109] In this way, the fuel reforming system 1 including the reciprocating engine 10 that runs a six-stroke cycle stores the carbon produced by the decomposition of hydrocarbon fuel in the cracker 50. The reciprocating engine 10 burns the hydrogen gas produced by the decomposition of hydrocarbon fuel, so no carbon oxides are produced due to combustion. The fuel reforming system 1 can achieve carbon neutrality.

[0110] The fuel reforming system 1 utilizes the heat and pressure generated by the reciprocating engine 10, and therefore does not require a separate dedicated device to generate the heat and / or pressure required to decompose the hydrocarbon fuel. The fuel reforming system 1 is useful as an on-board system.

[0111] (Water vapor adsorption part) 7 is a schematic diagram of an inner surface 51b of a support 51 in a decomposer 50. Note that FIG. 7 shows a microscopic region compared to FIGS.

[0112] The support 51 is cylindrical. An inner surface 51b, which is the surface of the support 51, is provided with recesses 56 and protrusions 57. The recesses 56 and the protrusions 57 are adjacent to each other on the inner surface 51b of the support 51. More specifically, the recesses 56 and the protrusions 57 are adjacent to each other on the inner surface 51b of the support 51. On the inner surface 51b of the support 51, the recesses 56 are recessed inward. On the inner surface 51b of the support 51, the protrusions 57 protrude outward.

[0113] A catalyst 52 is supported in recesses 56 on the inner surface 51b of the support 51. A water vapor adsorption portion 55 is arranged on protrusions 57 on the inner surface 51b of the support 51. More specifically, the water vapor adsorption portion 55 is applied to the protrusions 57 on the inner surface 51b of the support 51. The water vapor adsorption portion 55 is in the form of a film formed on the inner surface 51b of the support 51.

[0114] The catalyst 52 in the recessed portion 56 of the inner surface 51b of the support 51 and the water vapor adsorption portion 55 in the protruding portion 57 of the inner surface 51b of the support 51 are adjacent to each other. That is, on the inner surface 51b of the support 51, the water vapor adsorption portion 55 is disposed adjacent to the catalyst 52. Conversely, on the inner surface 51b of the support 51, the catalyst 52 is disposed adjacent to the water vapor adsorption portion 55.

[0115] The water vapor adsorption portion 55 in the convex portion 57 on the inner surface 51b of the cylindrical support 51 is located inside (inner circumferential side, gap A side, indicated by J) the catalyst 52 in the concave portion 56 on the inner surface 51b of the cylindrical support 51.

[0116] The water vapor adsorption section 55 in the convex portion 57 on the inner surface 51b of the cylindrical support 51 is located closer to the gap A to which the hydrocarbon fuel and combustion gas are supplied than the catalyst 52 in the concave portion 56 on the inner surface 51b of the cylindrical support 51. The water vapor adsorption section 55 comes into contact with the hydrocarbon fuel, the combustion gas, and water vapor described below before the catalyst 52 comes into contact with water vapor.

[0117] As described above, carbon (C) from the hydrocarbon fuel (CH fuel) adheres to the catalyst 52. As a result, the hydrocarbon fuel (CH fuel) is decomposed into carbon (C) and hydrogen gas (H2 gas).

[0118] As described above, in the recompression step S4, the hydrocarbon fuel (CH fuel) and the combustion gas are supplied to the cracker 50 (more specifically, the gap A between the inner surface 51b of the support 51 and the outer surface 53a of the hydrogen separation membrane 53). At this time, water vapor (HO) may be mixed into the combustion gas. That is, in addition to the hydrocarbon fuel (CH fuel) and the combustion gas, water vapor (HO) may also be present in the cracker 50. Then, not only carbon (C) but also water vapor (HO) may adhere to the catalyst 52.

[0119] When a large amount of steam (H2O) is present in the cracker 50, if the steam (H2O) adheres to the catalyst 52, the steam reforming reaction and the accompanying water-gas shift reaction shown in the following chemical reaction formulas occur, generating carbon dioxide (CO2): C8H18 + 8H2O = 8CO + 17H2 (steam reforming reaction). CO + H2O = CO2 + H2 (water-gas shift reaction).

[0120] In the cracker 50, the water vapor adsorption section 55 is provided to suppress the steam reforming reaction and the accompanying water gas shift reaction so as not to generate carbon dioxide. Water vapor is adsorbed onto the water vapor adsorption section 55. The water vapor adsorption section 55 is made of a material that generates heat when water vapor is adsorbed. The heat generated at this time is heat of adsorption (see the white arrow). The water vapor adsorption section 55 is made of, for example, zeolite or silica gel. The water vapor adsorption section 55 may also be made of other materials.

[0121] (Action and effect) The reciprocating engine 10 includes a compression stroke S2 ​​and an expansion stroke S3, followed by a recompression stroke S4 in which the combustion gas is compressed by the upward movement of the piston 12. The hydrocarbon fuel supply unit 30 supplies hydrocarbon fuel to the cracker 50.

[0122] The cracker 50 uses the heat and pressure of the combustion gas in the recompression step S4 to decompose the hydrocarbon fuel into carbon and hydrogen gas. The cracker 50 can efficiently decompose the hydrocarbon fuel. The carbon is stored in the cracker 50.

[0123] The hydrogen gas supply unit 40 supplies the hydrogen gas produced in the cracker 50 as fuel into the cylinders 11 of the reciprocating engine 10. The reciprocating engine 10 operates by combusting the hydrogen gas. No carbon oxides are produced by combustion. The reciprocating engine 10 can supply heat and pressure to the cracker 50 for cracking hydrocarbon fuel while outputting driving force to run the vehicle.

[0124] The fuel reforming system 1 can achieve carbon neutrality. Because the fuel reforming system 1 utilizes the heat and pressure generated by the reciprocating engine 10, a separate dedicated device is not required to generate the heat and / or pressure required to decompose the hydrocarbon fuel. The fuel reforming system 1 is useful as an on-board system installed in a vehicle.

[0125] Furthermore, the cracker 50 has a catalyst 52 to which carbon adheres and a water vapor adsorption section 55 to which water vapor is adsorbed. Here, the combustion gas supplied to the cracker 50 may contain water vapor.

[0126] In the cracker 50, the water vapor is adsorbed by the water vapor adsorption section 55, which prevents the water vapor from being adsorbed by the catalyst 52. This suppresses the steam reforming reaction and the accompanying water gas shift reaction in the cracker 50, making it difficult for carbon dioxide to be generated.

[0127] As described above, the generation of carbon dioxide can be suppressed in the fuel reforming system 1 mounted on a vehicle.

[0128] The heat generated when the water vapor is adsorbed by the water vapor adsorption section 55 can promote the decomposition reaction that decomposes the hydrocarbon fuel into carbon and hydrogen gas.

[0129] Since the water vapor adsorption section 55 is adjacent to the catalyst 52, water vapor can be encouraged to be adsorbed by the adjacent water vapor adsorption section 55 rather than being adsorbed by the catalyst 52.

[0130] The catalyst 52 is supported in the recesses 56 on the inner surface (surface) 51b of the support 51, and the water vapor adsorption sections 55 are arranged on the protrusions 57 on the inner surface (surface) 51b of the support 51. By providing a step between the catalyst 52 (recesses 56) and the water vapor adsorption sections 55 (protrusions 57), the catalyst 52 is separated, and adsorption of water vapor to the water vapor adsorption sections 55 can be further promoted, thereby further promoting adhesion of carbon to the catalyst 52.

[0131] The water vapor adsorption sections 55 in the convex sections 57 on the inner surface 51b of the cylindrical support 51 are located inside (on the void A side, indicated by J) the catalyst 52 in the concave sections 56 on the inner surface 51b of the cylindrical support 51. Therefore, the water vapor adsorption sections 55 come into contact with the water vapor before the catalyst 52 comes into contact with the water vapor. This allows the water vapor to be adsorbed by the water vapor adsorption sections 55 before the water vapor is adsorbed by the catalyst 52.

[0132] Second Embodiment A fuel reforming system 1 for a vehicle according to a second embodiment will be described. In the following description, the same components as those in the above embodiment will be denoted by the same reference numerals, and detailed description thereof may be omitted. Figure 8 shows a schematic cross section of an inner surface 51b of a support 51 in a cracker 50 according to the second embodiment.

[0133] The support 51 itself constitutes the water vapor adsorption section 55. The support 51 is made of, for example, zeolite or silica gel. The water vapor adsorption section 55 may be made of other materials.

[0134] The support 51 is configured in a cylindrical shape. Adjacent recesses 56 and protrusions 57 are provided on an inner surface 51b serving as the surface of the support 51. The recesses 56 and protrusions 57 on the inner surface 51b of the support 51 may be formed intentionally by processing or the like, or may be formed naturally as surface roughness during the manufacturing process.

[0135] The protrusions 57 on the inner surface 51b of the support 51 are exposed to the inside (toward the gap A, indicated by J) as water vapor adsorption portions 55. The recesses 56 on the inner surface 51b of the support 51 are covered with the catalyst 52. The catalyst 52 is preferably smaller than the recesses 56 on the inner surface 51b of the support 51. The catalyst 52 may cover only a part of or all of the recesses 56 on the inner surface 51b of the support 51.

[0136] The other configurations are the same as those in the first embodiment.

[0137] According to this embodiment, the support 51 constitutes the water vapor adsorption section 55, and has recesses 56 and protrusions 57 on the inner surface (surface) 51b. When attempting to arrange a catalyst 52 on the inner surface (surface) 51b of such a support 51, the catalyst 52 naturally rolls into the recesses 56 on the inner surface (surface) 51b of the support 51, and the protrusions 57 naturally become exposed as the water vapor adsorption section 55.

[0138] This makes it easy to arrange the catalyst 52 and the water vapor adsorption portion 55 on the inner surface (surface) 51b of the support 51.

[0139] Furthermore, the water vapor adsorption section 55 is likely to come into contact with water vapor before the catalyst 52 comes into contact with water vapor. Therefore, the water vapor can be adsorbed by the water vapor adsorption section 55 before the water vapor is adsorbed by the catalyst 52.

[0140] Third Embodiment A fuel reforming system 1 for a vehicle according to a third embodiment will be described. In the following description, the same components as those in the above-described embodiments will be given the same reference numerals, and detailed description thereof may be omitted. Figure 9 shows a front cross-sectional view of a cracker 50 according to the third embodiment.

[0141] The cracker 50 may include a cylindrical hydrogen separation membrane support 58 (hereinafter simply referred to as support 58), a plurality of ball-shaped supports 51 packed in the support 58, a catalyst 52 supported on an outer surface 51c of the ball-shaped support 51, a hydrogen separation membrane 53 provided in the support 58, a water vapor adsorption section 55 disposed on the outer surface 51c of the ball-shaped support 51, and a case 59 that houses the support 58. The support 58 is made of, for example, porous ceramic (such as zirconia). The support 58 may be disposed inside the hydrogen separation membrane 53 (the hydrogen separation membrane 53 may be disposed outside the support 58).

[0142] A gap A is formed between the outer surfaces (surfaces) 51c of the plurality of ball-shaped supports 51. In the gap A, hydrocarbon fuel (CH fuel), combustion gas, and water vapor (H2O) are present.

[0143] 7, adjacent recesses 56 and protrusions 57 are provided on the outer surface (surface) 51c of the ball-shaped support 51. A catalyst 52 is supported on the recesses 56 on the outer surface (surface) 51c of the ball-shaped support 51. A water vapor adsorption section 55 is arranged on the protrusions 57 on the outer surface (surface) 51c of the ball-shaped support 51. The water vapor adsorption section 55 is arranged adjacent to the catalyst 52 on the outer surface (surface) 51c of the ball-shaped support 51.

[0144] The water vapor adsorption portion 55 in the convex portion 57 on the outer surface (surface) 51c of the ball-shaped support 51 is located outside (towards void A, closer to water vapor) than the catalyst 52 in the concave portion 56 on the outer surface (surface) 51c of the ball-shaped support 51.

[0145] Carbon adheres to the catalyst 52. Water vapor is adsorbed to the water vapor adsorption section 55. The water vapor adsorption section 55 is made of a material that generates heat when water vapor is adsorbed thereto.

[0146] 8, the ball-shaped support 51 may itself constitute the water vapor adsorption portion 55. In this case, the protrusions 57 on the outer surface (surface) 51c of the ball-shaped support 51 are exposed to the outside (the side toward the gap A, closer to the water vapor) as the water vapor adsorption portion 55. The recesses 56 on the outer surface (surface) 51c of the ball-shaped support 51 are covered with the catalyst 52.

[0147] The other configurations are the same as those of the first and second embodiments.

[0148] <Fourth embodiment> A fuel reforming system 1 for a vehicle according to a fourth embodiment will be described. In the following description, the same components as those in the above-described embodiments will be given the same reference numerals, and detailed description thereof may be omitted. Figure 10 shows each step of a modified four-stroke cycle according to the fourth embodiment.

[0149] The reciprocating engine 10 executes a modified four-stroke cycle that includes a compression stroke T1 in which the air-fuel mixture containing hydrogen gas in the cylinder 11 is compressed by the rising piston 12, an expansion stroke T2 in which the piston 12 descends as the air-fuel mixture is burned, a recompression stroke T3 in which the rising piston 12 compresses the combustion gas, and a scavenging stroke T4 in which the piston 12 descends to discharge exhaust gas from the cylinder 11 through the exhaust port 15 and introduce intake air into the cylinder 11 through the intake port 13.

[0150] The other configurations are the same as those of the first to third embodiments.

[0151] <Other embodiments> Although the present disclosure has been described above with reference to preferred embodiments, such description is not limiting, and it goes without saying that various modifications, substitutions, or combinations are possible.

[0152] On the surfaces 51b and 51c of the support 51, the catalyst 52 may be supported on the protrusions 57, and the water vapor adsorption sections 55 may be arranged in the recesses .

[0153] The surfaces 51b and 51c of the support 51 may be flat and may not be provided with the recesses 56 and the protrusions 57. The water vapor adsorption section 55 may not be adjacent to the catalyst 52. The water vapor adsorption section 55 may be arranged separately from the support 51, instead of being arranged on the surfaces 51b and 51c of the support 51.

[0154] The support may be, for example, plate-shaped. In this case, it is preferable that a hydrogen separation membrane is inserted between the inner surfaces of two plate-shaped supports, and that a catalyst and a water vapor adsorption unit are disposed (supported) on the inner surface of the plate-shaped support. The cracker 50 may have any structure as long as it can crack hydrocarbon fuel by utilizing the heat and pressure of the combustion gas.

[0155] The reciprocating engine 10 may execute a cycle other than the six-stroke cycle and the modified four-stroke cycle, as long as the cycle includes at least a compression stroke, an expansion stroke, and a recompression stroke.

[0156] The reciprocating engine 10 may be a compression ignition engine. [Explanation of symbols]

[0157] S1 Intake stroke S2 compression stroke S3 Expansion stroke S4 Recompression process S5 Re-expansion stroke S6 exhaust stroke T1 compression stroke T2 Expansion stroke T3 Recompression process T4 Scavenging stroke A void J inside 1 Fuel reforming system 10 Reciprocating Engine 11 cylinders 12 pistons 17 Reformer port 18 On-off valve 25 Modified port injector 26 Hydrogen injector 30 Hydrocarbon fuel supply unit 40 Hydrogen gas supply unit 50 Decomposer 51 Support 51a Exterior 51b Inner surface (surface) 51c External surface (surface) 52 Catalyst 53 Hydrogen separation membrane 53a Exterior 53b Inside 54 cases 55 Water vapor adsorption section 56 Recess 57 Convex part 58 Support 70 Carbon Recovery Section 71 Housing 72 Exhaust channel 73 Discharge valve 74 Discharge hole

Claims

1. a reciprocating engine mounted on a vehicle and having pistons reciprocating within cylinders; a cracker for cracking a hydrocarbon fuel into carbon and hydrogen gas and storing the carbon; a hydrocarbon fuel supply unit that supplies the hydrocarbon fuel to the cracker; a hydrogen gas supply unit that supplies the hydrogen gas generated by the decomposer into the cylinder, the reciprocating engine executes a cycle including at least a compression stroke in which the air-fuel mixture containing the hydrogen gas in the cylinder is compressed by the rising of the piston, an expansion stroke in which the piston is lowered by combustion of the air-fuel mixture, and a recompression stroke in which the combustion gas is compressed by the rising of the piston, the cracker utilizes the heat and pressure of the combustion gas in the recompression stroke to crack the hydrocarbon fuel supplied from the hydrocarbon fuel supply unit into the carbon and the hydrogen gas, The decomposer comprises: a catalyst to which the carbon adheres; A fuel reforming system for a vehicle having a water vapor adsorption section that adsorbs water vapor.

2. 2. The fuel reforming system for a vehicle according to claim 1, wherein the water vapor adsorption portion is made of a material that generates heat when the water vapor is adsorbed thereon.

3. 3. The fuel reforming system for a vehicle according to claim 1, wherein the water vapor adsorption section is disposed adjacent to the catalyst.

4. The decomposer has a support, The surface of the support is provided with adjacent recesses and protrusions, the catalyst is supported on one of the recessed portion and the protruding portion, 4. The fuel reforming system for a vehicle according to claim 3, wherein the water vapor adsorption portion is disposed on the other of the recessed portion and the protruding portion.

5. the support is cylindrical and supports the catalyst on its inner surface as the surface; the recessed portion and the protruding portion are provided on the inner surface, 5. The fuel reforming system for a vehicle according to claim 4, wherein the water vapor adsorption section is located inside the catalyst.

6. the support constitutes the water vapor adsorption section, the protrusions are exposed as the water vapor adsorption portions, 5. The vehicle fuel reforming system according to claim 4, wherein the recess is covered with the catalyst.

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