Patent Document

RELATED APPLICATION  
       [0001]     The present application is based on, and claims priority from, Korean Application Number 2005-77861 filed on Aug. 24, 2005, the disclosure of which is hereby incorporated by reference herein in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a thin type micro reformer used in a fuel cell, and more particularly, to an improved thin type micro reformer having a fuel charger disposed between a reformer portion that reacts by absorbing heat and a CO remover that reacts by emitting heat, in order to partition the reformer portion and the CO remover. The reformer allows effective reforming response on a single sheet of substrate, an inner pressure inside the CO remover to decrease, and outside air to enter by means of a small pump.  
         [0004]     2. Description of the Related Art  
         [0005]     A recent increase in the use of mobile phones, PDAs, digital cameras, laptop computers, and other small, portable electronic devices—and especially, the beginning of DMB broadcasting for mobile phones—has given rise to a need for more effective power supplies for portable, compact terminals. Lithium ion rechargeable batteries used widely today provide power for only 2 hours of DMB viewing. While efforts are underway to enhance their performance, the fuel cell is viewed as an alternate solution to the above problem.  
         [0006]     Methods of such fuel cells include direct methanol type fuel cells that supply methanol to fuel electrodes and reformed hydrogen fuel cells (RHFC) that extract hydrogen from methanol to supply to fuel electrodes. RHFC fuel cells use hydrogen as fuel, as in a polymer electrode membrane (PEM), and have the benefits of high output, power capacity available by volume unit, and no byproducts other than water. However, a reformer needs to be added to the system, making the device unsuitable for miniaturization.  
         [0007]     To derive a high power output from such a fuel cell, a reformer is used to convert liquid fuel to hydrogen gas fuel. This type of reformer includes an evaporator for converting liquid methanol to a gaseous form, a reformer portion that converts methanol fuel to hydrogen through catalytic conversion at a temperature between 250° C. and 290° C., and a CO remover (or a PROX) that removes the byproduct carbon monoxide. Technology is needed to maintain the reformer portion (that reacts to absorb heat) at a temperature between 250° C. and 290° C., and the CO remover at a temperature between 170° C. and 200° C., in order to produce optimum reaction efficiency.  
         [0008]     However, silicon, that has favorable heat conducting characteristics, is used as a substrate material and must be operated within a region that has been heat insulated to prevent heat leakage to the outside. Thus it is difficult for the temperature on one substrate to be maintained in two other separate regions, and a configuration allowing for this is required.  
         [0009]     As shown in  FIG. 1 , a conventional compact reformer  250  is disclosed in Japanese Patent No. 2004-288573, which is hereby incorporated by reference. This conventional compact reformer  250  includes a heat insulating package  258  and combustion fuel evaporator  251 , a generator fuel evaporator  255 , a burner  252 , a CO remover  257 , another burner  254 , a reformer portion  256 , and yet another burner  253 , sequentially stacked within the heat insulating package  258 .  
         [0010]     Heat insulated supports  261  and  262  are installed below the combustion fuel evaporator  251  to support the combustion fuel evaporator  251 . The combustion fuel evaporator  251  is separated from the inner walls of the heat insulating package  258 . Accordingly, because this conventional reformer has a multi-layer structure, it is difficult to make compact.  
         [0011]     Another conventional compact reformer  350  is shown in  FIG. 2  and is disclosed in Japanese Patent No. 2003-45459, which is hereby incorporated by reference. This conventional reformer includes a first substrate  352  forming a flat cover, a second substrate  354  forming passages  354   a  on one side thereof and having a catalytic layer  354   b  formed within, and a third substrate  356  having a heat insulating cavity  356   b  with a mirror surface  356   a  formed therein. A reformer portion is formed through the passage  354   a  of the second substrate  354  and has the catalytic layer  354   b  that produces hydrogen gas and CO 2  from methanol and water, and a thin film heater  358  is provided underneath the catalytic layer  354   b  along the reformer portion.  
         [0012]     Although the provision of the heater  358  within the passages of the above conventional reformer raises heat efficiency, the structure is complex and is therefore difficult to make, and the catalytic layer  354   b  is limited to one portion, reducing reforming efficiency.  
         [0013]     A further conventional compact reformer  400  is shown in  FIG. 3  and is disclosed in Japanese Patent No. 2004-066008, which is hereby incorporated by reference. This conventional technology provides a highly heat conductive aluminum heat conducting portion  413  (for very efficient heat conducting) between two substrates  411  and  412 , and a reactive catalytic layer  416  within the fine passage  414  formed in the inner surface of the main substrate  411 .  
         [0014]     A combustion catalytic layer  417  is provided in a fine passage  415  formed in the inner surface of the combustion substrate  412 , and a thin film heater  423  is provided on the outer surface of the combustion substrate  412 .  
         [0015]     Combustible fuel supplied within the passage  415  is combusted through the combustion reaction on the combustion catalytic layer  417 . The heat energy produced through the combustion and the energy from the heating of the thin film heater  423  combine to heat the inside of the passage  414 .  
         [0016]     Accordingly, loss of heat energy supplied to the reactive catalytic layer  416  installed inside the passages  414  and  415  of the substrates  411  and  412  is reduced.  
         [0017]     However, in the above-described conventional structures, at least 3 thin films are stacked, forming a large reformer. Also, in order to supply air into the CO remover that has a high inner pressure, a large-sized air supplying pump must be used to supply pressurized air. Thus, miniaturization of components required by the reformer is problematic.  
       SUMMARY OF THE INVENTION  
       [0018]     Accordingly, the present invention is directed to a thin type reformer that substantially obviates one or more problems due to limitations and disadvantages of the related art.  
         [0019]     An object of the present invention is to provide a thin type reformer that is formed thinly in its entirety so that it can be conveniently used in a fuel cell, etc.  
         [0020]     Another object of the present invention is to provide an improved thin type reformer that induces a drop in interior pressure of a CO remover so that a small-sized air supplying pump can be used, miniaturizing the entire device.  
         [0021]     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
         [0022]     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a thin type reformer used for a fuel cell, including: a substrate forming a passage within; a fuel filling portion for filling the passage with fuel; a reformer portion forming a passage at one side of the fuel filling portion in the substrate, for reforming the fuel to hydrogen gas through a heat absorbing reaction; a CO remover forming a passage at an opposite side of the fuel filling portion in the substrate, for removing CO gas included in the hydrogen gas from the hydrogen gas through a heat radiating reaction; and a cover for covering an upper portion of the substrate and sealing the passages from an outside, wherein the fuel filling portion partitions the heat absorbing reaction of the reformer portion and the heat radiating reaction of the CO remover and induces a reforming reaction.  
         [0023]     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:  
         [0025]      FIG. 1  is a sectional view of a reformer according to the related art;  
         [0026]      FIG. 2  is a sectional view of an alternately structured reformer according to the related art;  
         [0027]      FIG. 3  is a sectional view of a reformer with yet another structure according to the related art;  
         [0028]      FIG. 4  is an exploded perspective view of a thin type reformer according to the present invention;  
         [0029]      FIG. 5  shows the structure of a thin type reformer according to an embodiment of the present invention, where  5   a  is a plan view,  5   b  is a sectional view taken along line A-A in  5   a , and  5   c  is a sectional view taken along line B-B in  5   a;    
         [0030]      FIG. 6  shows the structure of a thin type reformer according to another embodiment of the present invention, where  FIG. 6 ( a ) is a plan view,  FIG. 6 ( b ) is a sectional view taken along line C-C in  FIG. 6 ( a ), and  FIG. 6 ( c ) is a sectional view taken along line D-D in  FIG. 6 ( a ); and  
         [0031]      FIG. 7  is a plan view showing a heating member of a thin type reformer according to the present invention forming an electrical resistance circuit pattern on the bottom surface of a substrate.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0033]     As shown in  FIG. 4 , a thin type reformer  1  according to an embodiment of the present invention includes a substrate  10  forming a passage within. The substrate  10  may use silicon, metal, glass, ceramic, and heat resistant plastic, and indented passages are formed through etching into one side of the substrate  10 .  
         [0034]     That is, etching is performed on one side of the substrate  10 , forming a desired configuration of indented passages.  
         [0035]     A fuel filling portion  20  is provided to fill the insides of the passages of the substrate  10  with fuel. The fuel filling portion  20 , as shown in  FIGS. 4 and 5 , is formed at an approximate central location of the substrate  10 . The passage  22  of the fuel filling portion  20  is formed to proceed from one edge of the substrate  10  to the opposite edge of the substrate  10  by a plurality of partitioning walls  24  also extending from the one end to the other of the substrate  10 . After thus extending in one direction, the passage  22  is formed to proceed in the opposite direction.  
         [0036]     To fill liquid fuel (methanol) in the fuel filling portion  20 , a fuel filling hole  110  is formed in the cover  100  covering the top of the substrate  10 , so that the liquid fuel may be filled into the fuel filling portion  20 .  
         [0037]     At the exit end of the fuel filling portion  20 , an evaporator  30 , for heating the liquid fuel and converting it to a gaseous form, is formed. The evaporator  30  vaporizes liquid fuel so that it is in an optimum condition for reforming. A plurality of partitioning walls  34 , for forming a serpentine passage  32  of the evaporator  30 , do not need to have catalysts formed therein.  
         [0038]     However, the evaporator  30 , being a heat source, includes a heating member  36  that is formed in an electrically resistant circuit pattern at the bottom surface of the substrate  10  to heat the evaporator  30  on the upper surface of the substrate  10  through the substrate  10 .  
         [0039]     Also, in the inventive reformer, a passage  42  through which the fuel flows is formed within the substrate  10  at the downstream end of the evaporator  30 , and a reformer portion  40  is formed to reform the fuel into hydrogen gas through heat absorption reacting. The reformer portion  40  is biased to one side of the substrate  10  and formed at the downstream end of the evaporator  30 , and the passage  42  is connected to the passage  32  of the evaporator  30 . Partitioning walls  44  are formed to form the passage  42  of the reformer portion  40  in the same serpentine shape as the passage  32  of the evaporator  30 .  
         [0040]     Thus, the passages  32  and  42  of the evaporator  30  and the reformer portion  40  are formed in a serpentine zigzagging shape along the entire length of the passage  22  of the fuel filling portion  20  to one side thereof, are formed with a plurality of partitioning walls  34  and  44 , and include a catalyst  46  for reforming the fuel inside the passage  42  of the evaporator  40  to gaseous hydrogen. Hydrogen is converted to an abundance of reformed gas through catalytic reaction of fuel in the reformer portion  40 . As a catalyst  46  of the reformer portion  40 , Cu/ZnO or Cu/ZnO/Al 2 O 3  is used. The catalyst  46  may be mounted to the partitioning walls  44  forming the passage  42 .  
         [0041]     The reformer portion  40  reforms methanol or other hydrocarbon fuels to hydrogen gas through catalytic conversion accompanying heat absorption. A heat source that is needed for this process takes the form of a heating member  48  formed at the bottom of the substrate  10 . The heating member  48  of the reformer portion  40  is formed in a pattern of an electrically resistant circuit at the bottom surface of the substrate  10 , and heats the reformer portion  40  at the top of the substrate  10  through the substrate  10 . The heating member  48  of the reformer portion  40  may be integrally formed in a single electrically resistant circuit pattern with the heating member  36  of the evaporator  30 .  
         [0042]     Likewise, the heating member  48  of the reformer portion  40  is formed on the lower surface of the substrate  10 , and maintains the reformer portion  40  through the substrate  10  at a predetermined temperature, preferably between 250-290° C.  
         [0043]     Also, a CO remover  60  is formed at the downstream end of the reformer portion  40  of the substrate  10  in the present invention, and removes CO from the reformed gas generated by the reformer portion  40 .  
         [0044]     The CO remover  60  forms a passage on the opposite end of the fuel filling portion  20  inside the substrate  10 , and removes CO gas included in the hydrogen gas through heat emitting reaction.  
         [0045]     The reformer portion  40  supplies reformed gas including hydrogen gas, carbon monoxide, and carbon dioxide to the CO remover  60 , which is supplied through a narrower connecting portion  50  at the end of the passage. The connecting portion  50  extends along the edge of the substrate  10 , and a passage expanded portion  54  having a larger passage size than that of the connecting portion  50  is provided at the entrance of the CO remover  60 .  
         [0046]     The reformed gas including hydrogen gas, carbon monoxide, and carbon dioxide first passes through the narrower connecting portion  50  and is then discharged into the more expansive passage expanded portion  54 , leading to a decrease in pressure as it flows toward the CO remover  60 .  
         [0047]     The CO remover  60  forms a passage  62  through a plurality of partitioning walls  64  of the evaporator  30  and the reformer portion  40 . At the entrance end of the passage  62 , or the passage expanded portion  54 , an air entry hole  112  is formed in the cover  100  covering the top of the substrate  10 .  
         [0048]     A catalyst  66  for removing the CO gas produced by the reformer portion  40  is coated inside the passage  62 .  
         [0049]     When the reformed gas that enters the CO remover  60  and reacts with oxygen to remove CO, the catalyst used in the CO remover  60  may be one of Pt, Pt/Ru, and Cu/CeO/Al 2 O 3 .  
         [0050]     The CO remover  60  converts CO (that is harmful to humans) to CO 2  (that is not harmful to humans) through catalytic conversion accompanying heat emitting reaction. A heat source needed for this process is a heating member  68  for the CO remover  60 , the heat source formed on the bottom surface of the substrate  10 .  
         [0051]     The heating member  68  of the CO remover  60  is patterned on the bottom of the substrate  10  in the form of an electrically resistant circuit pattern, and heats the CO remover  60  on top of the substrate  10  through the substrate  10 .  
         [0052]     This heating member  68  of the CO remover  60  is formed in an electrically resistant circuit pattern, and maintains the CO remover  60  at a predetermined temperature of preferably 170-200° C. through an adequate power supply and control thereof.  
         [0053]     Also included in the present invention is the cover  100  that covers the top of the substrate  10  and seals the inner passages  22 ,  32 ,  42 , and  62  from the outside. The cover  100  may use the same materials as the substrate  10 , for example, silicon, metal, glass, ceramic, and heat resistant plastic, and may be integrated by being bonded to the top surface of the substrate  10 .  
         [0054]     This cover  100  may form recessed passages corresponding to the passages  22 ,  32 ,  42 , and  62  of the fuel filling portion  20 , the evaporator  30 , the reform portion  40 , and the CO remover  60 , so that inner volume of the passages formed by the substrate  10  and the cover  100  can be expanded.  
         [0055]     When bonded integrally to the substrate  10 , the cover  100  forms a reformed gas exhaust port  114  near the exit of the passage  62  of the CO remover  60 . That is, reformed gas including hydrogen gas and CO 2  is exhausted from the CO remover  60  to the outside of the substrate  10 .  
         [0056]     Accordingly, the cover  100  forms the fuel filling hole  110  at the fuel filling portion  20 , the air entry hole at the passage expanded portion  54  at the entrance of the CO remover  60 , and the reformed gas exhaust port  114  at the exit end of the CO remover  60 , so that liquid fuel is reformed into reformed gas including hydrogen and CO 2  that is exhausted.  
         [0057]     The thin type reformer  1  according to present invention fills liquid fuel through the fuel filling hole  110  to pass through the fuel filling portion  20  into the inner passage  22  formed by the substrate  10  and the cover  100 . Because this liquid fuel flows through roughly the central portion of the substrate  10 , it partitions the reformer portion  40  provided at one side of the substrate  10  and the CO remover  60  provided at the other side.  
         [0058]     This liquid fuel that passes through the fuel filling portion  20  enters the evaporator  30  and is vaporized at the temperature necessary for reforming, 250-290° C.  
         [0059]     Then, the evaporated fuel enters the reformer portion  40  formed at the downstream end of the evaporator  30 , and undergoes catalytic conversion accompanying heat absorption at a temperature of 250-290° C., where reformed gas including hydrogen gas, CO, and CO 2  is generated.  
         [0060]     This reformed gas passes through the narrow connecting portion  50  of the passage and flows downstream to the CO remover  60 . During this process, high temperature, high pressure reformed gas passes through the narrow connecting portion  50  and depressurizes when it enters the suddenly widened passage expanded portion  54  of the CO remover  60 , so that pressure of gas in the passage expanded portion  54  is substantially lower than in the reformer portion  40 .  
         [0061]     Then, the reformed gas passes through the air entry hole of the cover  100  over the passage expanded portion  54 , passing through the CO remover  60  while air is entering.  
         [0062]     Heat radiation occurs in the CO remover  60  at a temperature of 170-200° C., along with catalytic conversion of selective oxidization, converting CO to CO 2  in the reformed gas, so that it will be harmless to humans.  
         [0063]     In this state, reformed gas including hydrogen gas and the CO 2  is created while passing through the CO remover  60 , and the reformed gas is exhausted through the reformed gas exhaust port  114  in the cover  100 .  
         [0064]     The fuel filling portion  20 , through which liquid methanol fuel at room temperature is filled in the above process, is formed in the middle of the reformer portion  40  and the CO remover  60  in the present invention. Because a separate heater or catalyst heater is not installed, the 250-290° C. heat conducted from the reformer portion  40  and the 170-200° C. heat conducted from the CO remover  60  is absorbed by the liquid fuel. Thus, the fuel filling portion  20  can clearly divide the temperatures of the reformer portion  40  and the CO remover  60 .  
         [0065]     Air needed for the oxidization in the CO remover  60  must be supplied from the outside; and in this case, a pump (not shown) for supplying air through the air entry hole  112  in the cover  100  may be a small-capacity compact pump. That is, because reformed gas moves from the reformer portion  40  through the connecting portion  50  with a small cross-sectional area to the passage expanded portion  54  of the CO remover  60 , the drop in inner pressure at the passage expanded portion  54  causes the pressure in the passage expanded portion  54  to be substantially lower than the pressure in the reformer portion  40 , so that outside air can easily enter through the air entry hole  112 .  
         [0066]     Accordingly, the pump that supplies air to the air entry hole  112  may be smaller compared to those in the related art.  
         [0067]      FIG. 6  shows the structure of a thin type reformer  1 ′ according to another embodiment of the present invention.  
         [0068]     This thin type reformer  1 ′ according to the alternate embodiment, when compared to the thin type reformer  1  shown in  FIG. 5 , has enlarged passages  42  and  62  of the reformer portion  40  and the CO remover  60 . Also the catalysts  46 ′ and  66 ′ of the reformer portion  40  and the CO remover  60  are not formed by coating, etc. on the partitioning walls  44  and  64  of the passage  42  and  62 , but are filled with particles, between which the fuel and gases flow.  
         [0069]     Specifically, particles made of Cu/ZnO or Cu/ZnO/Al 2 O 3  for the catalyst  46 ′ in the reformer portion  40  may be filled inside the passage  42  of the reformer portion  40 .  
         [0070]     Here, the particles may be formed of a size that prevents them from exiting through the evaporator  30  at the front of the reformer portion  40  or the connecting portion  50  at the rear of the reformer portion  40 .  
         [0071]     Also, the catalyst  66 ′ used in the CO remover  60  may take the form of particles formed of one of Pt, Pt/Ru, and Cu/CeO/Al 2 O 3 .  
         [0072]     The catalyst particles  66 ′ in the CO remover may be formed in a size preventing them from exiting from the passage expanded portion  54  at the entrance of the CO remover  60  or the reformed gas exhaust hole  114  at the exit of the CO remover  60 .  
         [0073]     Also, the cover  100  that is bonded to and covers the substrate  10  may form recessed passages corresponding to the passages  22 ,  32 ,  42 , and  62  of the fuel filling portion  20 , the evaporator  30 , the reformer  40 , and the CO remover  60 , so that the interior volume of the passages  22 ,  32 ,  42 , and  62  formed by the substrate  10  and cover  100  is expanded.  
         [0074]     In the thin type reformer  1 ′ according to the alternate embodiment of the present invention, the hot and high-pressured reformed gas is transferred from the narrow connecting portion  50  connecting the reformer portion  40  and the CO remover  60  to the passage expanded portion  54  to effectively reduce the pressure. Therefore, the capacity of the pump supplying air to the air entry hole  112  does not need to be large in this embodiment, and can be a compact pump.  
         [0075]     Compared to the thin type reformer  1  shown in  FIGS. 4 and 5 , the thin type reformer  1 ′ according to the alternate embodiment of the present invention is generally the same in terms of materials for the substrate  10  and the positions of the fuel filling portion  20 , the evaporator  30 , the reformer portion  40 , the CO remover  60 , and the heating members, so that the two reformers have similar functions.  
         [0076]     Although the thin type reformer  1 ′ according to the alternate embodiment of the present invention is different from the thin type reformer  1  shown in  FIGS. 4 and 5 , the particles allow more freedom in the placement or shapes of the catalysts  46 ′ and  66 ′, and thus a simpler forming therof.  
         [0077]     The thin type reformer according to the present invention provides a fuel filling portion between a reformer portion and a CO remover on a single substrate, to block heat between the reformer portion and the CO remover, creating 2 separate temperature regions and increasing the reaction efficiencies for each respective region.  
         [0078]     Also, the substrate in which passages are formed and a cover covering the passages allow fuel filling, evaporating, reforming, and CO removal to be sequentially performed on a single surface of the substrate, allowing a low profile of the reformer.  
         [0079]     Furthermore, the reformed gas moving from the reforming portion to the CO remover moves from a portion of a passage with a small sectional area to a passage expanded portion with a larger sectional area, so that the inner pressure of the CO remover in the passage expanded portion is reduced, allowing the use of a small-sized air supplying pump. The total volume required by the reformer can therefore be reduced.  
         [0080]     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Technology Category: 5