Abstract:
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 a fuel, in order to restrict heat deformation of a reactor, the engine system 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.

Description:
FIELD OF THE INVENTION 
       [0001]    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 
       [0002]    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. 
         [0003]    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). 
         [0004]    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. 
         [0005]    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 
       [0006]    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. 
         [0007]    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. 
         [0008]    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. 
         [0009]    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. 
         [0010]    Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF DRAWINGS 
         [0011]      FIG. 1  is an explanatory and schematic view showing an entire configuration of an engine system according to a first embodiment of the invention. 
           [0012]      FIG. 2  is a cross-sectional view showing a reactor according to the first embodiment of the invention, taken along the line II-II shown in  FIG. 1 . 
           [0013]      FIG. 3  is an explanatory cross-sectional view showing one section perpendicular to a fuel flowing direction (a direction from the backward side toward the forward side of  FIG. 2 ) of one fuel passageway according to the first embodiment of the invention, enlarged only in the vertical direction. 
           [0014]      FIG. 4  is a perspective view showing an example of a plate disposed in a fuel passageway according to the first embodiment of the invention. 
           [0015]      FIG. 5  is a perspective view showing a plate disposed in an inside of a fuel passageway of a reactor according to a second embodiment of the invention. 
           [0016]      FIG. 6  is a perspective view showing a plate disposed in an inside of a fuel passageway of a reactor according to a third embodiment of the invention. 
           [0017]      FIG. 7  is a perspective view showing a plate disposed in an inside of a fuel passageway of a reactor according to a fourth embodiment of the invention. 
           [0018]      FIG. 8  is a perspective view showing a plate disposed in an inside of a fuel passageway of a reactor according to a fifth embodiment of the invention. 
           [0019]      FIG. 9  is an external perspective view schematically showing a plate disposed in an inside of a fuel passageway of a reactor according to a sixth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiment 1 
       [0020]    Hereinafter, a first embodiment of the invention will be described in detail with reference to the accompanying drawings.  FIG. 1  is an explanatory and schematic view showing an entire configuration of an engine system according to the present embodiment. 
         [0021]    An engine system  100  according to the present embodiment includes an engine  10  employing a hydrogen medium as a fuel. The engine  10  is connected to an intake pipe  11  and an exhaust pipe  12 , and a reactor  1  is disposed in a portion of the exhaust pipe  12 . 
         [0022]    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”. 
         [0023]    The hydrogen medium as a fuel is introduced from a hydrogen medium tank  14  to a pump  30  (see the arrow F 01 ). Then, the hydrogen medium is pressurized by the pump  30 , and is injected into a reactor  1  via a pipe  41  (see the arrow F 02 ). Since the hydrogen medium contacts with a catalyst at a high temperature in the reactor  1 , chemical reaction therebetween is promoted. Subsequently, the hydrogen medium is decomposed to produce reaction gas including dehydrogenation medium and hydrogen gas. 
         [0024]    The produced gas passes through a pipe  44  (see the arrow F 03 ) and is supplied to a separator  16 . In the separator  16  provided with a cooler, the produced gas is separated into hydrogen and other dehydrogenation mediums. The separated dehydrogenation mediums pass through a pipe  45  (see the arrow F 04 ) and are stored in a dehydrogenation medium tank  15 . On the other hand, the separated hydrogen passes through a pipe  46  (see the arrow F 05 ) and is supplied to the inside (not shown) of the engine  10  via the intake pipe  11 . The hydrogen combusted in the engine  10  becomes high-temperature exhaust gas. The high-temperature exhaust gas passes through the exhaust pipe  12  (see the arrow F 06 ), is supplied as a heat source to the reactor  1 , and then is discharged to the atmosphere via the reactor  1  (see the arrow F 07 ). 
         [0025]      FIG. 2  is a cross sectional view showing the reactor  1  when taken along the line II-II shown in FIG.  1 . A structure of the reactor is formed by a housing  53  provided with an exhaust passageway  52  and a fuel passageway  51  therein which are juxtaposed to each other. Specifically, the reactor  1  has a structure in which the exhaust passage  52  and the fuel passageway  51  having rectangular flow-passage sections are alternately superposed on a wall of the housing  53  interposed therebetween. According to the reactor  1  with such a configuration, exhaust heat of the engine  10  is transmitted from the exhaust passage  52  to the adjacent fuel passageway  51  with 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 reactor  1 . 
         [0026]    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 in  FIG. 2 ) is used as the exhaust passage  52 , it is possible to prevent the temperature of the fuel passageway  51  from decreasing. With such a configuration, since it is possible to maintain the fuel passageway  51  at a high temperature, it is possible to more realize a compact in size of the reactor. 
         [0027]      FIG. 3  is an explanatory cross sectional view showing a section perpendicular to a fuel flowing direction (a direction from the backward side to the forward side of  FIGS. 2 and 3 ) of one fuel passageway  51 , which is enlarged only in a vertical direction.  FIG. 4  is a perspective view showing an example of an after-mentioned plate disposed in the fuel passageway  51 . Additionally, in  FIG. 4 , in the same manner as  FIG. 3 , the plate is enlarged in a vertical direction. 
         [0028]    As shown in  FIG. 3 , multiple sheets of very thin plates  61  are fitted and inserted into one fuel passageway  51  shown in  FIG. 2  while being laminated in a passage space. Then, as shown in  FIG. 4 , each plate  61  is substantially formed into a rectangular plate shape, and forms a carrier in which a first plate  64  and a second plate  65  carry a catalyst. A thickness of the first plate  64  is larger than that of the second plate  65 , and the second plate  65  is formed into a recessed plane. Then, as shown in  FIG. 3 , the adjacent plates  61  and  61  superposed to form a lamination in a vertical direction of the drawing form a plate fuel passageway  62  in such a manner that the surfaces of the first plates  64  and  64  are combined with each other in a lamination direction. The plate  61  is provided with a slit  63  for dividing the surface of the plate  61  in a fuel flowing direction. In terms of the slit  63 , the plate fuel passageways  62  of the laminated plates  61  communicate with one another. 
         [0029]    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 passageway  62  becomes non-uniform, the plate fuel passageway  62  is capable of flowing the fuel on the upstream side and the downstream side of the non-uniform part in terms of the slit  63 . 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. 
         [0030]    For example, even when a part of the plate fuel passageway  62  is closed by heat deformation, since the slit  63  is 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 reactor  1  as a whole. 
         [0031]    Additionally, since the multiple sheets of plates  61  are fitted into the fuel passageway  51  while being superposed or laminated (see  FIG. 3 ) in such a manner that the slits  63  are 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. 
         [0032]    Here, since a heat-resisting property needs to be ensured in the housing  53  and a catalyst carrying function needs to be ensured in the plate  61 , in some cases, the housing  53  and the plate  61  may be formed of different metal materials. In accordance with a combination of different metal materials, the plate  61  may be largely thermal-expanded in a transverse direction (in a horizontal direction of  FIG. 3 ) of a surface perpendicular to a fuel flowing direction. In the conventional art, since a plate side surface  61 S is restrained in the housing  53 , it is difficult to avoid deformation of the plate  61 . However, in the present embodiment, since the slit  63  is provided, the thermal-expanded amount is absorbed, thereby preventing large deformation such as buckling caused by heat expansion. 
         [0033]    Since the dehydrogenation reaction is endothermic reaction, sufficient heat needs to be supplied, and hence a heat supply passageway to the reactor  1  is important. A main heat transmission route to the fuel passageway  51  is configured such that the exhaust heat of the engine is transmitted to the housing  53 , is conducted to the plate  61 , and then is transmitted to the plate fuel passageway  62  (fuel passageway  51 ). In the present embodiment, since a minimum width of the slit  63  is smaller than that of the plate fuel passageway  62 , most of hydrogen medium flows through the plate fuel passageway  62 . 
         [0034]    Additionally, in the present embodiment, since the slit  63  is formed in the vicinity of the center in a transverse direction of the plate  61 , heat is high-efficiently supplied from the housing  53  located in the outside in a transverse direction of  FIG. 3  to the plate side surface  61 S, and is supplied from the plate side surface  61 S to the center in a transverse direction of the plate  61 . Additionally, since the minimum width of the slit  63  is smaller than the thickness of the plate  61 , it is possible to increase the surface area of the plate  61 . 
         [0035]    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 reactor  1 . 
       Embodiment 2 
       [0036]    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 (see  FIG. 1  or the like), and the repetitive description thereof will be therefore omitted. The different parts from the first embodiment will be mainly described. 
         [0037]      FIG. 5  is a perspective view showing a plate  161  disposed in the inside (see  FIGS. 1 and 2 ) of the fuel passageway  51  of the reactor  1  according to the present embodiment. For example, a size of the plate  161  is not more than that of 200 mm×500 mm×0.5 mm. A size of the fuel passageway  62  (see  FIG. 3 ) formed between the laminated plates  161  and  161  is not more than that of 1 mm. Additionally, these dimensions are examples, but the present embodiment is not limited to these dimensions. 
         [0038]    The present embodiment is different from the first embodiment in that the shape of the plate  161  shown in  FIG. 5  is different. That is, in the present embodiment, a right plate  161 R and a left plate  161 L shown in  FIG. 5  are bridge-connected to each other via a first connection portion  167  and a second connection portion  168 . In other words, the second plates  165  divided by the slit  163  are bridge-connected to each other via the first connection portion  167  and a second connection portion  168 . With such a configuration, even when the left and right plates  161 L and  161 R are connected to each other, it is possible to absorb the heat deformation. 
         [0039]    Likewise, since the left and right plates  161 L and  161 R are bridge-connected to each other via the connection portions  167  and  168 , it is possible to reduce an influence of the heat deformation during an operation. Also, since the plates  161  are integrally formed with each other, it is possible to easily carry out the positioning operation of the plate  161  upon manufacturing the reactor  2 , and thus to reduce a manufacture cost and a manufacture time. 
         [0040]    For example, when the second connection portion  168  having a width of 0.2 mm or less is bridge-connected, elastic deformation easily occurs to thereby absorb the expansion of the plate  161 . 
       Embodiment 3 
       [0041]    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 (see  FIG. 1  or the like) or the second embodiment (see  FIG. 5 ), and the repetitive description thereof will be omitted. The different parts from the first embodiment and the second embodiment will be mainly described. 
         [0042]      FIG. 6  is a perspective view showing a plate  261  disposed in the inside of the fuel passageway  51  of the reactor  1  according to the present embodiment. 
         [0043]    In the present embodiment, protrusions  266  are formed in a second plate  265 , and the other configurations are the same as those of the second embodiment. It is desirable that a height of each protrusion  266  is the same as that of the first plate  64  got higher in a stepped shape from the second plate  265  or twice higher than that of the first plate  64 . In case of the same height, it is desirable that the protrusions  266  are formed in both surfaces of the second plate  265 . On the other hand, in case of twice height, it is desirable that the protrusion  266  is formed in one surface. 
         [0044]    In the adjacent laminated plates  261  and  261 , a gap between the second plates  265  and  265  opposed to each other forms a fuel passageway. With such a configuration, since the protrusions  266  and  266  formed in the second plates  265  and  265  opposed to each other are brought into contact with each other or the protrusion  266  is brought into contact with the opposed second plate  265  as well as the first plates  64  combined with each other, it is possible to maintain a gap between the adjacent plates  261  and  261  by using the protrusion  266  as a support, and thus to prevent the non-uniform state of the fuel passageway. 
         [0045]    A shape of the protrusion  266  may be a semi-spherical shape, a conical shape, or a pyramid shape, but it is desirable that the protrusion  266  is 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 protrusion  266  is brought into contact with the adjacent laminated plates  261  or is brought into contact with the housing  53  (see  FIG. 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 projection  266  is not more than 10 mm which depth does not prevent the hydrogen medium from flowing. 
       Embodiment 4 
       [0046]    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. 
         [0047]      FIG. 7  is a perspective view showing a plate  361  disposed in the inside of the fuel passageway  51  of the reactor  1  according to the present embodiment. 
         [0048]    In the present embodiment, a plurality of slits  363  is formed in a second plate  365 . Since the plurality of slits  363  is provided, it is possible to increase the surface area of the plate  361 . Since the performance of the reactor  1  is improved by increasing the contact area between the hydrogen medium and the plate  361  carrying the catalyst, it is possible to realize a compact in size of the reactor  1 . Even in the present embodiment, like the second embodiment shown in  FIG. 5 , basically, a right plate  361 R and a left plate  361 L are connected to each other via a first connection portion  367  and a second connection portion  368 . In the example shown in  FIG. 7 , the second connection portion  368  is provided at two positions in a heat transmission direction, but in a case where heat resistance of the second connection portion  368  is relatively high, it is possible to facilitate the heat supply by providing the second connection portion  368 , for example, at three positions or more. 
       Embodiment 5 
       [0049]    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. 
         [0050]      FIG. 8  is a perspective view showing a plate  461  disposed in the inside of the fuel passageway  51  of the reactor  1  according to the present embodiment. 
         [0051]    In the present embodiment, a plurality of slits  463  is formed in the plate  461 . The slit  463  includes a longitudinal slit  463 L extending in a flow passageway direction and a transverse slit  463 S extending in a direction perpendicular to the flow passageway, which are formed in two directions meeting at right angles. 
         [0052]    Then, in the present embodiment, as shown in  FIG. 8 , the longitudinal slit  463 L 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 plate  461 . The transverse slit  463 S 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 plate  461 . Here, the slits  463 L and the  463 S do not communicate with each other, and connection portions  467  and  468  are formed therebetween, respectively. 
         [0053]    Likewise, since the longitudinal slit  463 L and the transverse slit  463 S 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 passageway  62  (see  FIG. 3 ) formed by laminating the plates  461  by using a stepped portion between the first plate  64  and the second plate  465  passes through a position in the vicinity of any one of the slits  463  ( 463 L and  463 S), 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 passageways  62 , . . . ,  62 , it is possible to improve the reaction efficiency of the reactor  1 . 
       Embodiment 6 
       [0054]    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. 
         [0055]      FIG. 9  is an external perspective view schematically showing only the portion where the plates are laminated as shown in  FIG. 3  in a fuel flowing direction, in a plate  561  disposed in the inside of a fuel passageway  551  of the reactor according to the present embodiment. 
         [0056]    Three laminated plates  571 ,  572 , and  573  having the plurality of laminated plates  561  are 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 plate  573  corresponding to a fuel entrance (see the arrow IN) is largely deformed by heat, the plate fuel passageway  62  of 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 passageway  62  is ensured in the other laminated plates  571  and  572  less influenced by heat than the laminated plate  573 . Accordingly, the fuel passing through a slit  563  of the laminated plate  573  passes through the plate fuel passageway  62  of the laminated plates  571  and  572 , thereby preventing deterioration of the reaction efficiency of the reactor  1 . 
         [0057]    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. 
         [0058]    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. 
         [0059]    It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.