Engine system

An engine system in which hydrogen is employed as a fuel, including a reactor configured to cause a reaction using a catalyst, in which the reactor is constituted by alternately disposing plural exhaust passages and plural fuel passageways of the engine system with a wall interposed therebetween; at least one carrier configured to carry the catalyst and to be formed in a substantially rectangular plate shape is fitted in at least one of fuel passageways; and the carrier is provided with a plate portion which has a surface disposed in a fuel flowing direction and is formed in a substantially rectangular plate shape and at least one slit portion which divides the surface of the plate portion in the fuel flowing direction.

FIELD OF THE INVENTION

The present invention relates to an engine system. More specifically, the present invention relates to an engine system which employs as a fuel, either hydrogen produced from a hydrogen containing medium in terms of reaction using a catalyst or mixture of the hydrogen and the hydrogen containing medium.

DESCRIPTION OF RELATED ART

Since the engine system which employs gasoline as a fuel discharges carbon dioxide, hydrogen has been gaining attention as an alternative fuel for the countermeasure to global warming. However, usage of hydrogen is difficult in that hydrogen is combustible material and is highly explosive. Particularly, a high technique must be required for storing hydrogen in a gas state or a liquid state, and it is also a difficult technique to store hydrogen so from the viewpoint of safety and a large weight of a storage container.

Therefore, a technique has been developed in which hydrogen is stored while being contained in a hydrogen medium, hydrogen gas is extracted in terms of a chemical reaction at a necessary time, and then the hydrogen gas is supplied to the engine system. However, it is necessary to provide a constant heat source all the time when proceeding chemical reaction due to the fact that the chemical reaction takes place as an endothermic reaction. For example, in an automobile mounting thereon the engine system employing the gasoline as a fuel, when the afore-mentioned engine supplied with the hydrogen gas in terms of the chemical reaction, is mounted to replace the gasoline engine, a certain technique has been proposed in which the exhaust gas from the engine is used as the heat source (see JP-A-2005-299499).

Such a reactor incorporated in this type of engine system is operated under a high-temperature circumstance due to the exhaust gas from the engine. In some cases, a problem may arise in that the reactor itself is subjected to a thermal deformation due to different heat expansions of the respective parts of the reactor caused by either a combination of materials having different linear expansion coefficients or a difference in local temperature of the reactor. In case of severe deformation, since respective sectional areas of a plurality of fuel flow passageways or exhaust gas flow passage become non-uniform, heat amount supplied from the exhaust gas becomes non-uniform, thereby causing such a problem that reaction efficiency of the reactor is deteriorated as a whole.

Although there is disclosed a technique of a heat exchanger provided with a heat transfer mechanism which is the same as that of the reactor in various industrial fields, the technique is not based on the particular circumstance as mounted on the above-described automobile. For this reason, in spite of the fact that the engine system needs to be compact in size, it is difficult to avoid an increase in size or a complication of the engine system.

SUMMARY OF THE INVENTION

An object of the invention is to provide an engine system which is able to reduce an influence due to heat deformation of a reactor and in which either hydrogen produced from a hydrogen containing medium in terms of reaction using a catalyst or a mixture of the hydrogen and the hydrogen containing medium is employed as a fuel.

In order to achieve the above-described object, according to an aspect of the invention, there is provided an engine system in which either hydrogen produced from a hydrogen containing medium in terms of reaction using a catalyst or a mixture of the hydrogen and the hydrogen containing medium is employed as fuel, the engine system including a reactor configured to cause a reaction using the catalyst, wherein the reactor is configured by alternately disposing a plurality exhaust passageways and a plurality of fuel passageways of the engine system with a wall interposed therebetween, wherein at least one carrier configured to carry the catalyst and to be formed in a substantially rectangular plate shape is interposed in the inside of at least one of fuel passageways, and wherein the carrier is provided with a plate portion which has a surface disposed in a fuel flowing direction and is formed in a substantially rectangular plate shape, and at least one slit portion which divides the surface of the plate portion in a fuel flowing direction.

According to the above-described configuration of the invention, in the engine system in which either hydrogen produced from a hydrogen containing medium in terms of reaction using a catalyst or a mixture of the hydrogen and the hydrogen containing medium is employed as a fuel, since the slit is formed in the carrier of the reactor so as to reduce a variation in heat transmission circumstance in the inside of the reactor, it is possible to reduce an influence of heat deformation on the reactor.

According to the engine system, since it is possible to reduce the influence of the heat deformation of the reactor, it is possible to restrict deterioration of reaction efficiency of the reactor as a whole.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a first embodiment of the invention will be described in detail with reference to the accompanying drawings.FIG. 1is an explanatory and schematic view showing an entire configuration of an engine system according to the present embodiment.

An engine system100according to the present embodiment includes an engine10employing a hydrogen medium as a fuel. The engine10is connected to an intake pipe11and an exhaust pipe12, and a reactor1is disposed in a portion of the exhaust pipe12.

Here, the hydrogen medium indicates all mediums capable of chemically storing and discharging hydrogen, which includes hydrocarbon-based fuel such as gasoline, light oil, kerosene, heavy oil, decaline, cyclohexane, methyl-cyclohexane, naphthalene, benzene, and toluene, mixed fuel thereof, hydrogen peroxide, ammonia, nitrogen, or oxygen. In the below description, the medium chemically storing hydrogen is referred to as “hydrogen medium” and the medium chemically discharging hydrogen is referred to as “dehydrogenation medium”.

The hydrogen medium as a fuel is introduced from a hydrogen medium tank14to a pump30(see the arrow F01). Then, the hydrogen medium is pressurized by the pump30, and is injected into a reactor1via a pipe41(see the arrow F02). Since the hydrogen medium contacts with a catalyst at a high temperature in the reactor1, chemical reaction therebetween is promoted. Subsequently, the hydrogen medium is decomposed to produce reaction gas including dehydrogenation medium and hydrogen gas.

The produced gas passes through a pipe44(see the arrow F03) and is supplied to a separator16. In the separator16provided with a cooler, the produced gas is separated into hydrogen and other dehydrogenation mediums. The separated dehydrogenation mediums pass through a pipe45(see the arrow F04) and are stored in a dehydrogenation medium tank15. On the other hand, the separated hydrogen passes through a pipe46(see the arrow F05) and is supplied to the inside (not shown) of the engine10via the intake pipe11. The hydrogen combusted in the engine10becomes high-temperature exhaust gas. The high-temperature exhaust gas passes through the exhaust pipe12(see the arrow F06), is supplied as a heat source to the reactor1, and then is discharged to the atmosphere via the reactor1(see the arrow F07).

FIG. 2is a cross sectional view showing the reactor1when taken along the line II-II shown in FIG.1. A structure of the reactor is formed by a housing53provided with an exhaust passageway52and a fuel passageway51therein which are juxtaposed to each other. Specifically, the reactor1has a structure in which the exhaust passage52and the fuel passageway51having rectangular flow-passage sections are alternately superposed on a wall of the housing53interposed therebetween. According to the reactor1with such a configuration, exhaust heat of the engine10is transmitted from the exhaust passage52to the adjacent fuel passageway51with the wall interposed therebetween, and dehydrogenation reaction of the hydrogen medium is promoted in terms of the heat transmission, thereby realizing high-efficient heat exchange and a compact in size of the reactor1.

Additionally, a reaction speed of the dehydrogenation reaction increases as the temperature increases. Therefore, in the present embodiment, since the outermost flow passageway (the uppermost portion and the downmost portion shown inFIG. 2) is used as the exhaust passage52, it is possible to prevent the temperature of the fuel passageway51from decreasing. With such a configuration, since it is possible to maintain the fuel passageway51at a high temperature, it is possible to more realize a compact in size of the reactor.

FIG. 3is an explanatory cross sectional view showing a section perpendicular to a fuel flowing direction (a direction from the backward side to the forward side ofFIGS. 2 and 3) of one fuel passageway51, which is enlarged only in a vertical direction.FIG. 4is a perspective view showing an example of an after-mentioned plate disposed in the fuel passageway51. Additionally, inFIG. 4, in the same manner asFIG. 3, the plate is enlarged in a vertical direction.

As shown inFIG. 3, multiple sheets of very thin plates61are fitted and inserted into one fuel passageway51shown inFIG. 2while being laminated in a passage space. Then, as shown inFIG. 4, each plate61is substantially formed into a rectangular plate shape, and forms a carrier in which a first plate64and a second plate65carry a catalyst. A thickness of the first plate64is larger than that of the second plate65, and the second plate65is formed into a recessed plane. Then, as shown inFIG. 3, the adjacent plates61and61superposed to form a lamination in a vertical direction of the drawing form a plate fuel passageway62in such a manner that the surfaces of the first plates64and64are combined with each other in a lamination direction. The plate61is provided with a slit63for dividing the surface of the plate61in a fuel flowing direction. In terms of the slit63, the plate fuel passageways62of the laminated plates61communicate with one another.

With such a configuration, even when a part of the plate is deformed by the heat influence and a part of the flow-passage section of the plate fuel passageway62becomes non-uniform, the plate fuel passageway62is capable of flowing the fuel on the upstream side and the downstream side of the non-uniform part in terms of the slit63. In terms of the flow of the fuel, it is possible to more appropriately distribute the hydrogen medium (redistribution) and thus to make the reaction uniform.

For example, even when a part of the plate fuel passageway62is closed by heat deformation, since the slit63is provided, a flow passageway capable of avoiding the closed part exists at other parts. Accordingly, since the fuel flows into the flow passageway, it is possible to reduce a non-uniform state of the transmitted heat amount, and thus to restrict deterioration of the reaction efficiency of the reactor1as a whole.

Additionally, since the multiple sheets of plates61are fitted into the fuel passageway51while being superposed or laminated (seeFIG. 3) in such a manner that the slits63are laminated so that the positions thereof are coincident with each other, even when the flow-passageway section becomes non-uniform or the flow passageway is closed by the heat deformation, it is possible to facilitate the uniform redistribution of the fuel.

Here, since a heat-resisting property needs to be ensured in the housing53and a catalyst carrying function needs to be ensured in the plate61, in some cases, the housing53and the plate61may be formed of different metal materials. In accordance with a combination of different metal materials, the plate61may be largely thermal-expanded in a transverse direction (in a horizontal direction ofFIG. 3) of a surface perpendicular to a fuel flowing direction. In the conventional art, since a plate side surface61S is restrained in the housing53, it is difficult to avoid deformation of the plate61. However, in the present embodiment, since the slit63is provided, the thermal-expanded amount is absorbed, thereby preventing large deformation such as buckling caused by heat expansion.

Since the dehydrogenation reaction is endothermic reaction, sufficient heat needs to be supplied, and hence a heat supply passageway to the reactor1is important. A main heat transmission route to the fuel passageway51is configured such that the exhaust heat of the engine is transmitted to the housing53, is conducted to the plate61, and then is transmitted to the plate fuel passageway62(fuel passageway51). In the present embodiment, since a minimum width of the slit63is smaller than that of the plate fuel passageway62, most of hydrogen medium flows through the plate fuel passageway62.

Additionally, in the present embodiment, since the slit63is formed in the vicinity of the center in a transverse direction of the plate61, heat is high-efficiently supplied from the housing53located in the outside in a transverse direction ofFIG. 3to the plate side surface61S, and is supplied from the plate side surface61S to the center in a transverse direction of the plate61. Additionally, since the minimum width of the slit63is smaller than the thickness of the plate61, it is possible to increase the surface area of the plate61.

With such a configuration, since it is possible to increase the area carrying the catalyst necessary for the dehydrogenation reaction, it is possible to realize a compact in size of the reactor1.

Next, the engine system according to a second embodiment of the invention will be described. In the engine system according to the present embodiment, the same reference numerals designate the same or like components as those of the first embodiment (seeFIG. 1or the like), and the repetitive description thereof will be therefore omitted. The different parts from the first embodiment will be mainly described.

FIG. 5is a perspective view showing a plate161disposed in the inside (seeFIGS. 1 and 2) of the fuel passageway51of the reactor1according to the present embodiment. For example, a size of the plate161is not more than that of 200 mm×500 mm×0.5 mm. A size of the fuel passageway62(seeFIG. 3) formed between the laminated plates161and161is not more than that of 1 mm. Additionally, these dimensions are examples, but the present embodiment is not limited to these dimensions.

The present embodiment is different from the first embodiment in that the shape of the plate161shown inFIG. 5is different. That is, in the present embodiment, a right plate161R and a left plate161L shown inFIG. 5are bridge-connected to each other via a first connection portion167and a second connection portion168. In other words, the second plates165divided by the slit163are bridge-connected to each other via the first connection portion167and a second connection portion168. With such a configuration, even when the left and right plates161L and161R are connected to each other, it is possible to absorb the heat deformation.

Likewise, since the left and right plates161L and161R are bridge-connected to each other via the connection portions167and168, it is possible to reduce an influence of the heat deformation during an operation. Also, since the plates161are integrally formed with each other, it is possible to easily carry out the positioning operation of the plate161upon manufacturing the reactor2, and thus to reduce a manufacture cost and a manufacture time.

For example, when the second connection portion168having a width of 0.2 mm or less is bridge-connected, elastic deformation easily occurs to thereby absorb the expansion of the plate161.

Next, the engine system according to a third embodiment of the invention will be described. In the engine system according to the present embodiment, the same reference numerals are given to the same components as those of the first embodiment (seeFIG. 1or the like) or the second embodiment (seeFIG. 5), and the repetitive description thereof will be omitted. The different parts from the first embodiment and the second embodiment will be mainly described.

FIG. 6is a perspective view showing a plate261disposed in the inside of the fuel passageway51of the reactor1according to the present embodiment.

In the present embodiment, protrusions266are formed in a second plate265, and the other configurations are the same as those of the second embodiment. It is desirable that a height of each protrusion266is the same as that of the first plate64got higher in a stepped shape from the second plate265or twice higher than that of the first plate64. In case of the same height, it is desirable that the protrusions266are formed in both surfaces of the second plate265. On the other hand, in case of twice height, it is desirable that the protrusion266is formed in one surface.

In the adjacent laminated plates261and261, a gap between the second plates265and265opposed to each other forms a fuel passageway. With such a configuration, since the protrusions266and266formed in the second plates265and265opposed to each other are brought into contact with each other or the protrusion266is brought into contact with the opposed second plate265as well as the first plates64combined with each other, it is possible to maintain a gap between the adjacent plates261and261by using the protrusion266as a support, and thus to prevent the non-uniform state of the fuel passageway.

A shape of the protrusion266may be a semi-spherical shape, a conical shape, or a pyramid shape, but it is desirable that the protrusion266is formed into a surface-contacting shape such as a cylindrical shape or a prism shape because the contact parts are easily deformed when, due to the heat deformation, the protrusion266is brought into contact with the adjacent laminated plates261or is brought into contact with the housing53(seeFIG. 3) as an outer wall to be slid thereon. It is also desirable that the representative diameter in the case of, for example, the cylindrical projection266is not more than 10 mm which depth does not prevent the hydrogen medium from flowing.

Next, the engine system according to a fourth embodiment of the invention will be described. In the engine system according to the present embodiment, the same reference numerals are given to the same components as those of the first embodiment to the third embodiment, and the repetitive description thereof will be omitted. The different parts from the first embodiment to the third embodiment will be mainly described.

FIG. 7is a perspective view showing a plate361disposed in the inside of the fuel passageway51of the reactor1according to the present embodiment.

In the present embodiment, a plurality of slits363is formed in a second plate365. Since the plurality of slits363is provided, it is possible to increase the surface area of the plate361. Since the performance of the reactor1is improved by increasing the contact area between the hydrogen medium and the plate361carrying the catalyst, it is possible to realize a compact in size of the reactor1. Even in the present embodiment, like the second embodiment shown inFIG. 5, basically, a right plate361R and a left plate361L are connected to each other via a first connection portion367and a second connection portion368. In the example shown inFIG. 7, the second connection portion368is provided at two positions in a heat transmission direction, but in a case where heat resistance of the second connection portion368is relatively high, it is possible to facilitate the heat supply by providing the second connection portion368, for example, at three positions or more.

Next, the engine system according to a fifth embodiment of the invention will be described. In the engine system according to the present embodiment, the same reference numerals are given to the same components as those of the first embodiment to the fourth embodiment, and the repetitive description thereof will be omitted. The different parts from the first embodiment to the fourth embodiment will be mainly described.

FIG. 8is a perspective view showing a plate461disposed in the inside of the fuel passageway51of the reactor1according to the present embodiment.

In the present embodiment, a plurality of slits463is formed in the plate461. The slit463includes a longitudinal slit463L extending in a flow passageway direction and a transverse slit463S extending in a direction perpendicular to the flow passageway, which are formed in two directions meeting at right angles.

Then, in the present embodiment, as shown inFIG. 8, the longitudinal slit463L is formed in a linear shape in a fuel flowing direction at a position slightly deviated from the center point in a transverse direction of a surface meeting at right angles with a fuel flowing direction of the plate461. The transverse slit463S is formed in a linear shape in a direction meeting at right angles with a fuel flowing direction at a position slightly deviated from the center point in a longitudinal direction of a surface in a fuel flowing direction of the plate461. Here, the slits463L and the463S do not communicate with each other, and connection portions467and468are formed therebetween, respectively.

Likewise, since the longitudinal slit463L and the transverse slit463S are provided, it is possible to reduce heat deformation in a flow passageway direction where fuel flows and a direction meeting at right angles with the flow passageway. Additionally, fluid flowing to the fuel passageway62(seeFIG. 3) formed by laminating the plates461by using a stepped portion between the first plate64and the second plate465passes through a position in the vicinity of any one of the slits463(463L and463S), thereby facilitating the flow of the fluid between the adjacent flow passageways. From this point, since it is possible to make uniform the flow of the fuel between the fuel passageways62, . . . ,62, it is possible to improve the reaction efficiency of the reactor1.

Next, the engine system according to a sixth embodiment of the invention will be described. In the engine system according to the present embodiment, the same reference numerals are given to the same components as those of the first embodiment to the fifth embodiment, and the repetitive description thereof will be omitted. The different parts from the first embodiment to the fifth embodiment will be mainly described.

FIG. 9is an external perspective view schematically showing only the portion where the plates are laminated as shown inFIG. 3in a fuel flowing direction, in a plate561disposed in the inside of a fuel passageway551of the reactor according to the present embodiment.

Three laminated plates571,572, and573having the plurality of laminated plates561are disposed with a predetermined gap L therebetween in a fuel flowing direction. With such a configuration, it is possible to obtain the following advantages. That is, when the laminated plate573corresponding to a fuel entrance (see the arrow IN) is largely deformed by heat, the plate fuel passageway62of the fuel entrance (see the arrow IN) becomes non-uniform, thereby causing a case in which in some parts, the fuel does not contact with the medium. Even in this case, the uniform plate fuel passageway62is ensured in the other laminated plates571and572less influenced by heat than the laminated plate573. Accordingly, the fuel passing through a slit563of the laminated plate573passes through the plate fuel passageway62of the laminated plates571and572, thereby preventing deterioration of the reaction efficiency of the reactor1.

As described above, the preferred embodiments of the invention have been described. The invention is not limited to the description of the drawings, but may be modified within a scope not departing from the spirit of the invention.

For example, the slit is formed in a linear shape, but may be formed in a curve shape or a wave shape. Additionally, the number of connection portions formed as bridge in the slit may increase. Likewise, various modifications may be made within a scope not departing from the spirit of the invention that the influence of the heat deformation reduces.