Vaporizer, fuel cell having vaporizer, and vaporizing method

Disclosed is a vaporizer including a first liquid suction section to suck a first liquid; a second liquid suction section to suck a second liquid; and a heating element to heat the first liquid suction section and the second liquid suction section to vaporize the first liquid and the second liquid.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vaporizer for vaporizing liquid, a fuel cell having the vaporizer, and a vaporizing method.

2. Description of the Related Art

In recent years, fuel cells receives attention as clean power supply having high energy converting efficiency, and the fuel cells are widely introduced commercially such as fuel cell automobiles and electrified housings. Studies are carried out for commercial viability of the power supply by the fuel cells also in a portable electronic equipment such as cellular phones and notebook personal computers in which research and development of downsizing are pursued abruptly.

Fuel cells are classified into two types, i.e., a reforming type and a fuel direct type. The reforming type is a type in which hydrogen is produced from fuel and water using a reforming device, and the produced hydrogen is supplied to a fuel cell like the reforming of water vapor. In the fuel direct type, fuel and water are not reformed, and they are supplied to a fuel cell. Generally, fuel and water are stored in the form of liquid, and the fuel and water are vaporized and then, a mixture of the fuel and water is supplied to the reforming device. Therefore, a vaporizer for vaporizing fuel and water is required, and research and development concerning such vaporizer are pursued together with development of the fuel cell (see Japanese Patent Applications Laid-open Nos. 2004-47260 and 2001-263649 for example).

If such a vaporizer is made compact, since the flow rate is small, fuel is easily heated excessively. Therefore, fuel is irregularly bumping, liquid drop is mixed in the vaporized liquid and it is difficult to control the stable vaporization. When a mixture of a plurality kinds of liquid having different boiling points such as fuel and water is vaporized, influence of bumping is serious, and it is more difficult to control.

When a post reforming device or a fuel cell is disposed, such an instable factor makes reforming performance by the reforming device or electric power generating performance by the fuel cell instable.

SUMMARY OF THE INVENTION

Hence, the present invention has been accomplished to solve such a problem, and it is a major object of the invention to provide a vaporizer and a vaporizing method capable of efficiently supplying a mixture when a plurality kinds of liquid are to be vaporized.

According to a first aspect of the present invention, there is provided a vaporizer comprising:

a first liquid suction section to suck a first liquid;

a second liquid suction section to suck a second liquid; and

a heating element to heat the first liquid suction section and the second liquid suction section to vaporize the first liquid and the second liquid.

According to a second aspect of the present invention, there is provided a fuel cell having the above-mentioned vaporizer according to the first aspect of the present invention.

According to a third aspect of the present invention, there is provided a vaporizer comprising:

a first liquid suction section which sucks a first liquid and which vaporize the first liquid,

a second liquid suction section which sucks a second liquid and which vaporize the second liquid, and

a heating element provided closer to the first liquid suction section than the second liquid suction section.

According to a fourth aspect of the present invention, there is provided a vaporizing method of liquid, comprising:

interposing a partitioning material between a plurality of liquid sucking sections;

allowing one end of each of the liquid sucking sections to absorb different kinds of liquids;

allowing the liquids respectively absorbed by the liquid sucking sections to penetrate the other ends; and

heating the other end of each of the liquid sucking sections to vaporize the liquids.

According to a fifth aspect of the present invention, there is provided a vaporizer comprising:

a heat insulation case;

a liquid sucking section, a suction side end thereof for sucking liquid being disposed outside of the heat insulation case and a discharging side end thereof for vaporizing and discharging the liquid sucked by the suction side end being accommodated in the heat insulation case; and

a heater to heat a discharging side end of the liquid sucking section.

According to a sixth aspect of the present invention, there is provided a vaporizer comprising:

a liquid sucking section to suck liquid from a suction side end and to allow the sucked liquid to penetrate to a discharging side end;

a heater to heat the discharging side end of the liquid sucking section; and

a heat radiating section which is in contact with the suction side end and which has a thermal conductivity higher than that of the liquid sucking section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The best mode for carrying out the present invention will be explained with reference to the drawings. Although various limitations which are preferable for carrying out the invention are proposed in the following exemplary examples, the scopes of the invention are not limited to the exemplary examples and illustrated examples.

First Exemplary Example

FIG. 1is a schematic sectional view of a vaporizer1.FIG. 2is an exploded perspective view of an upper surface, a front surface and a right surface of the vaporizer1.

As shown inFIGS. 1 and 2, the vaporizer1includes a first liquid suction section3, a second liquid suction section2, a partition section4, a contractile tube5, an elastic tube6, a first liquid introducing section7, a second liquid introducing section13, a discharging section8, a heat insulation case9, a heating element10and a temperature sensor11.

The second liquid suction section2is a core material formed into a rod-like shape, more specifically, a columnar shape. The second liquid suction section2is a porous body in which a fine space is formed, and the second liquid suction section2can suck liquid by capillary action. The second liquid suction section2may be formed by solidifying inorganic fiber or organic fiber using bonding material (e.g., epoxy resin), may be formed by sintering inorganic powder, may be formed by solidifying inorganic powder using bonding material (e.g., epoxy resin), may be a mixture body of graphite and glassy carbon, or may be formed by binding a large number of thread materials comprising inorganic fiber or organic fiber and solidifying the same using bonding material. An acrylic fiber flux core can be used as the second liquid suction section2for example. Alternatively, the plurality kinds of the above materials may be mixed and used as the second liquid suction section2.

The second liquid suction section2is fitted into the cylindrical partition section4, a front end and a rear end of the liquid sucking section2are opened, and its outer side of the liquid sucking section2is covered with the partition section4. Liquid sucked by the second liquid suction section2and liquid sucked by the first liquid suction section3can not penetrate the partition section4. The partition section4is made of material which is not deformed and deteriorated by heat of the heating element10. The partition section4is provided with a cylindrical metal material such as stainless steel (SUS 316) for example. Cross sectional shapes of the partition section4and the second liquid suction section2in a direction intersecting with a plane ofFIG. 1at right angles are concentric. An outer peripheral surface of the second liquid suction section2and an inner peripheral surface of the partition section4come into intimate contact with each other. The length of the second liquid suction section2and the length of the partition section4are equal to each other, and both end surfaces of the second liquid suction section2and both end surfaces of the partition section4are aligned.

The first liquid suction section3is formed into a cylindrical shape having a space into which the second liquid suction section2and the partition section4are inserted. The first liquid suction section3is a porous body surrounding the internal space, and can suck liquid by capillary action. The first liquid suction section3is made of the same member as that of the second liquid suction section2. The second liquid suction section2covered with the partition section4is fitted into an inner wall of the first liquid suction section3, the cross sectional shapes of the second liquid suction section2and the first liquid suction section3in a direction intersecting with the plane ofFIG. 1at right angles are concentric, and the first liquid suction section3and the second liquid suction section2are partitioned by the partition section4. Therefore, liquid which penetrates the first liquid suction section3does not move to the second liquid suction section2through the partition section4, and liquid which penetrates the second liquid suction section2does not move to the first liquid suction section3through the partition section4. An inner diameter of the first liquid suction section3and an outer diameter of the partition section4are substantially equal to each other, and an inner peripheral surface of the first liquid suction section3is in intimate contact with an outer peripheral surface of the partition section4. The second liquid suction section2, the partition section4and the first liquid suction section3are concentrically laminated on one another in the radial direction.

The length of the first liquid suction section3is shorter than the lengths of the second liquid suction section2and the partition section4. Portions of the second liquid suction section2and the partition section4project from a rear end of the first liquid suction section3, and front ends of the second liquid suction section2and the partition section4are aligned with a front end of the first liquid suction section3.

The partition section4and the second liquid suction section2are fitted into the first liquid suction section3. The first liquid suction section3is fitted into the contractile tube5, and the outer peripheral surface of the first liquid suction section3is in intimate contact with the contractile tube5. The length of the contractile tube5is shorter than the length of the first liquid suction section3, and both ends of the first liquid suction section3project from the respective ends of the contractile tube5. The contractile tube5is made of a material having heat-shrinkable characteristics, such as polyolefin and polyvinylidene fluoride. The contractile tube5heat-shrinks, after heating, and comes into intimate contact with the first liquid suction section3without gap. At that time, the contractile tube5is not impregnated into a sidewall of the first liquid suction section3and liquid does not leak outside from the holes of the first liquid suction section3.

A front end and a rear end of the first liquid introducing section7are opened, an inner diameter of the front end opening is substantially equal to an outer diameter of the first liquid suction section3, and an inner diameter of the rear end opening thereof is substantially equal to an outer diameter of the partition section4. A rear end of the first liquid suction section3is fitted into the front end opening of the first liquid introducing section7, and a portion of the contractile tube5is also fitted into the front end opening of the first liquid introducing section7. The second liquid suction section2and the partition section4are fitted into the first liquid suction section3. When the first liquid suction section3is soft, the first liquid suction section3may be shrunk slightly by the contractile tube5. In this state, the rear end of the first liquid suction section3is accommodated in the front end opening of the first liquid introducing section7. The front end of the first liquid introducing section7covers the rear end of the contractile tube5such as to be superposed on the rear end of the contractile tube5and thus, the first liquid suction section3is not exposed. Even when the first liquid suction section3is hard and is not easily deformed, since the contractile tube5functions as a cushioning material having a sufficient stress, the first liquid introducing section7can come into intimate contact with the first liquid suction section3excellently.

The second liquid suction section2and the partition section4are fitted such that they extend from the rear end opening of the first liquid introducing section7. A rear end surface of the first liquid suction section3is separated from a bottom74of the rear end of the first liquid introducing section7, and a ring-like space71is formed between the bottom74of the first liquid introducing section7and the rear end surface of the first liquid suction section3. The second liquid suction section2passes through a center of the space71, and the second liquid suction section2is inserted into the partition section4. An edge of the rear end opening of the first liquid introducing section7is provided with a rubber O-ring12, and the first liquid introducing section7and the partition section4are in intimate contact with each other without gap. Therefore, first liquid α charged into the space71does not leak from between the first liquid introducing section7and the partition section4.

A first liquid-introducing opening72projects from a sidewall of the first liquid introducing section7. An introducing hole73penetrates from a tip end of the first liquid-introducing opening72to an inner peripheral surface of the first liquid introducing section7along a center axis of the first liquid-introducing opening72. The introducing hole73is in communication with the space71, and the first liquid α is introduced into the space71. The first liquid introducing section7is not deteriorated or deformed at the boiling point of the first liquid α. The first liquid introducing section7is resin, metal or ceramic which does not corrode by contact with the first liquid α. The first liquid-introducing opening72is connected to a tube (not shown) through which the first liquid α is sent out.

The second liquid introducing section13covers the rear end of the partition section4which projects from the first liquid introducing section7. The second liquid introducing section13is a cylindrical tube which surrounds a space16. A rear end of the second liquid introducing section13is provided with a second liquid-introducing opening15. The second liquid-introducing opening15is connected to a tube (not shown) through which second liquid β is sent out. The second liquid β is sucked from the second liquid suction section2introduced from the second liquid-introducing opening15. The second liquid introducing section13is connected to or adhered to the partition section4. It is preferable that coefficients of expansion of the partition section4and the second liquid suction section2are close to each other. The second liquid introducing section13may be fitted into the partition section4such that it comes into contact with the first liquid introducing section7.

The discharging section8is integrally formed with a cylindrical accommodating section81located in a rearward position, a discharging opening82which is connected to the accommodating section81and located in a forward position, and a flange83projecting from an outer edge of a joint between the accommodating section81and the discharging opening82. A rear end of the accommodating section81and a front end of the discharging opening82are opened at the discharging section8. An outer diameter of the discharging opening82is smaller than an outer diameter of the accommodating section81, and an inner diameter of an opening of the discharging opening82is smaller than an inner diameter of an opening of the accommodating section81.

The second liquid suction section2and the partition section4are inserted into the first liquid suction section3. A front portion of the first liquid suction section3is accommodated in the accommodating section81such that the accommodating section81is in intimate contact with a sidewall of the front portion of the first liquid suction section3. At that time, since the rear end of the accommodating section81covers the front end of the contractile tube5such as to be superposed thereon, the first liquid suction section3is not exposed. Even when the first liquid suction section3is hard and is not easily deformed, since the contractile tube5functions as a cushioning material having a sufficient stress, the discharging section8can come into intimate contact with the first liquid suction section3excellently.

The discharging section8has thermal conductivity as high as 10 (W·m−1K−1) or higher, and is made of material which is less prone to corrode or deform with respect to the first liquid α or mixture γ (mixture of gas of second liquid β and gas of first liquid α), and is made of metal such as brass and copper.

The elastomer elastic tube6is fitted from a joint between the first liquid introducing section7and the contractile tube5to a joint between the discharging section8and the contractile tube5. That is, the first liquid suction section3is fitted into the accommodating section81together with the second liquid suction section2and the partition section4, a portion of the outer peripheral surface of the first liquid suction section3projecting from the contractile tube5is in contact with the inner surface of the accommodating section81, a portion of the accommodating section81is inserted into the elastic tube6, and the accommodating section81is sandwiched between the inner peripheral surface of the elastic tube6and the outer peripheral surface of the first liquid suction section3. The elastic tube6is in intimate contact with the contractile tube5, the first liquid introducing section7and the discharging section8without gap.

The length of the elastic tube6is shorter than that of the first liquid suction section3, and a front portion of a sidewall of the accommodating section81projects from the elastic tube6. The contractile tube5and the elastic tube6may not constitute a double structure. Only one of the contractile tube5and the elastic tube6may be provided if the first liquid α or gas vaporized from the first liquid α does not leak. If liquid or gas does not seep from the outer peripheral surface of the first liquid suction section3by providing the outer peripheral surface of the first liquid suction section3with a film or the like, both the contractile tube5and elastic tube6may be omitted.

Since the contractile tube5, the elastic tube6, the first liquid introducing section7and the discharging section8are formed as tubes as described above, the first liquid suction section3and the second liquid suction section2are isolated from each other by the partition section4and accommodated in the contractile tube5, the elastic tube6, the first liquid introducing section7, the discharging section8and the internal space of the second liquid introducing section13. When the outer peripheral surface of the first liquid suction section3is provided with a film through which the first liquid α can not pass instead of the contractile tube5and the elastic tube6, the film, the first liquid introducing section7and the discharging section8function as tubes for accommodating the first liquid suction section3, the second liquid suction section2and the partition section4.

Front end surfaces of the second liquid suction section2, the first liquid suction section3and the partition section4are separated from a bottom86of the discharging section8, and a space84is formed between these end surfaces and the bottom86of the discharging section8. The space84is in communication with a discharge hole82aof the discharging opening82. The discharging opening82is connected to a tube (not shown) through which the mixture γ is sent out.

The heating element10which is a heater such as a heating coil is wound around the accommodating section81of the discharging section8, and the heating element10and the accommodating section81are in contact with each other. Since the heating element10is wound around the accommodating section81, the first liquid suction section3is closer to the heating element10than the second liquid suction section2. The heating element10is made of electric heating material and is a resistance which generates heat if voltage is applied. A nickel-cobalt wire may be used as the heating element10for example. The heating element10is coated with heat-resistant adhesive14such as ceramic adhesive and epoxy adhesive, and the heating element10is fixed to the accommodating section81by the adhesive14. The heating element10may be used instead of the ceramic heater, or both the heating element10and the ceramic heater may be used.

An insertion hole85is formed in the radial direction in the flange83of the discharging section8. The insertion hole85is not extended to the accommodating section81or the internal space of the discharging opening82, and a bottom of the insertion hole85reaches a portion near an end surface of the second liquid suction section2. The temperature sensor11is inserted into the insertion hole85, the temperature sensor11is located near the end surface of the first liquid suction section3and with this, the temperature sensor11is embedded in the discharging section8. The temperature sensor11is a thermocouple, a thermistor or a resistance thermometer bulb. The temperature sensor11is coated with insulator so that it is insulated from its periphery. The temperature sensor11detects a temperature corresponding to heat of the heating element10transmitted through the discharging section8or adhesive14.

If the heating element10is heated, the first liquid α which penetrates the first liquid suction section3by heat propagated to the accommodating section81from the heating element10is vaporized from the front end surface of the first liquid suction section3and is discharged into the space84. Further, the heat from the heating element10is propagated to the second liquid suction section2through the partition section4, the second liquid β which penetrates the second liquid suction section2is vaporized from the front end surface of the second liquid suction section2and is discharged into the space84, the second liquid β is mixed with gas vaporized from the first liquid α, the space84is filled with the mixture γ, and the mixture γ is discharged from a discharge hole82aof the discharging opening82. The space84functions as a space in which a plurality of gases are mixed.

Since the second liquid suction section2is surrounded by the first liquid suction section3and the partition section4, it is preferable that the heating temperature of the second liquid suction section2is set lower than that of the first liquid suction section3. In this case, it is preferable that the first liquid α which is heated to a higher temperature is material having a boiling point higher than that of the second liquid β which is heated to a lower temperature.

The heat insulation case9surrounds a front portions of the heating element10and the first liquid suction section3and a front portion of the second liquid suction section2so that heat of the heating element10, the front portion of the first liquid suction section3and the front portion of the second liquid suction section2heated by the heating element10are not released outside. The accommodating section81and the flange83of the discharging section8are accommodated in the heat insulation case9.

If the entire first liquid suction section3and the entire second liquid suction section2are heated, the first liquid α is vaporized from the rear end surface of the first liquid suction section3, and the second liquid β is vaporized from the rear end surface of the second liquid suction section2. These bubbles hinder the penetration of the first liquid α of the first liquid suction section3or the penetration of the second liquid β of the second liquid suction section2, and the amount of mixture γ discharged from the discharging opening82becomes instable. Since a rear portion of the first liquid suction section3and a rear portion of the second liquid suction section2are not covered with the heat insulation case9, heat of the rear portion of the first liquid suction section3and heat of the rear portion of the second liquid suction section2are relatively smoothly radiated, the temperature of the rear portion of the first liquid suction section3does not reach the boiling point of the first liquid α, and the temperature of the rear portion of the second liquid suction section2does not reach the boiling point of the second liquid β.

The heating element10heats the front portion of the first liquid suction section3to the boiling point of the first liquid α, and heats the front portion of the second liquid suction section2to the boiling point of the second liquid β. Therefore, if the first liquid α is vaporized from the front end surface of the first liquid suction section3, the first liquid α charged into the rear portion of the first liquid suction section3is spontaneously moved forward of the first liquid suction section3by the capillary action. If the second liquid β is vaporized from the front end surface of the second liquid suction section2, the second liquid β charged into the rear portion of the second liquid suction section2is spontaneously moved forward of the second liquid suction section2by the capillary action.

An upper side case91and a lower side case92are combined to form an accommodation space in the heat insulation case9. Both the upper case91and lower case92are made of insulation material such as a ceramic obtained by sintering titanium oxide, potassium oxide, calcium oxide, and engineering plastic such as silicon oxide, PES (sulf-polyether), styrenefoam, urethanefoam.

Fan-like recesses are formed in a lower edge of a front surface of the upper case91and an upper edge of a front surface of the lower case92. If the upper case91and the lower case92are coupled to each other, these recesses are coupled to each other, and a through hole93is formed. The discharging opening82of the discharging section8is fitted into the through hole93, and the discharging opening82projects from the front surface of the heat insulation case9. To fix the position, the flange83of the discharging section8is in contact with an internal surface of the front surface of the heat insulation case9, but a space may be provided between the flange83and the inner surface of the front surface of the heat insulation case9to enhance the insulating performance. If a groove is formed in a surface of the flange83opposed to the heat insulation case9, the flange83and the heat insulation case9abut against each other and the alignment can be carried out, an insulation gap having low thermal conductivity can be formed by this groove, and the insulating effect can be enhanced.

A lower edge of a back surface of the upper case91and an upper edge of a back surface of the lower case92are formed with fan-like recesses, the upper case91and the lower case92are coupled to each other, these recesses are coupled to each other, and a through hole94is formed. The elastic tube6, the contractile tube5, the front portion of the first liquid suction section3, the partition section4and the front portion of the second liquid suction section2are fitted into the through hole94. The elastic tube6and a wall surface of the through hole94come into intimate contact with each other, and a gap between the wall surface of the through hole94and the outer peripheral surface of the first liquid suction section3are sealed by the elastic tube6and the contractile tube5.

Wire-through holes95to97are formed in an upper surface of the upper case91, and grooves95ato97aextending to the back surface of the upper case91from the wire-through holes95to97are formed in an upper surface of the upper case91. A wire11aof the temperature sensor11is inserted through the wire-through hole95, the wire11ais bent and extended in the groove95a. Similarly, wires10aand10bof both ends of the heating element10are inserted into wire-through holes96and97, the wires10aand10bare bent and extended in the grooves96aand96a.

The temperature sensor11is connected to a controller50through the wire11a, and the heating element10is also connected to the controller50through the wires10aand10b. A signal indicative of a detection temperature of the temperature sensor11is input to the controller50. The controller50controls the heating element10so that the temperature of the first liquid suction section3and the temperature of the second liquid suction section2become equal to desired temperatures based on the detected temperature of the temperature sensor11. More specifically, when the detected temperature of the temperature sensor11becomes higher than an upper threshold value, the controller50reduces or turns off electricity supplied to the heating element10, and when the detected temperature of the temperature sensor11becomes lower than a lower threshold value (lower threshold value<upper threshold value), the controller50increases or turns on the electricity supplied to the heating element10, and when the detected temperature of the temperature sensor11is higher than the lower threshold value and lower than the upper threshold value, the controller50maintains the electricity supplied to the heating element10.

Next, the operation of the vaporizer1and the vaporizing method using the vaporizer1will be explained.

If voltage is applied to the heating element10, the heating element10generates heat, and a member accommodated in the heat insulation case9is heated. Here, in the inside portion of the heating element10, as a member is further from the heating element10, the heating temperature is reduced. Therefore, the temperature of a portion of the first liquid suction section3closer to the heating element10is higher than the temperature of the further second liquid suction section2. Rear ends of the first liquid suction section3and second liquid suction section2are outside of the heat insulation case9, the front end is in the heat insulation case, and the heating element10is wound around the front end. Therefore, the temperature of the first liquid suction section3is reduced from the end thereof on the side of the discharging opening82toward the end thereof on the side of the first liquid-introducing opening72, and the temperature of the second liquid suction section2is reduced from the end thereof on the side of the discharging opening82toward the end thereof on the side of the second liquid-introducing opening15.

When the detected temperature of the temperature sensor11is higher than the lower threshold value and lower than the upper threshold value, the temperature of the first liquid suction section3reaches the boiling point of the first liquid α at the end thereof on the side of the discharging opening82, less than the boiling point of the first liquid α at the end of the first liquid suction section3on the side of the first liquid-introducing opening72, the temperature of the second liquid suction section2reaches the boiling point of the sa at the end of the second liquid suction section2on the side of the discharging opening82, and less than the boiling point of the second liquid β at the end of the second liquid suction section2on the side of the second liquid-introducing opening15. In the following description, in the first liquid suction section3and the second liquid suction section2, ends thereof around which the heating element10is wound is called a discharging side end, and the other end opposite from the discharging side end is called a suction side end.

In a state where the discharging side ends of the second liquid suction section2and the first liquid suction section3are heated by the heating element10, if the second liquid β is sent through the second liquid introducing section13by a pump or the like, the second liquid β is sucked into the second liquid suction section2from the suction side end of the second liquid suction section2. The second liquid β sucked into the second liquid suction section2moves toward the discharging side end by the capillary action, and the second liquid β is heated by the heating element10at the discharging side end of the second liquid suction section2and is vaporized. Then, the vaporized gas is perspired into the space84in the accommodating section81from the end surface of the second liquid suction section2on the discharging side. Since the second liquid β is vaporized in the second liquid suction section2in this manner, it is possible to suppress the bumping of the second liquid β.

If the first liquid α is supplied into the space71in the first liquid introducing section7through the introducing hole73by a pump or the like, the first liquid α is sucked into the first liquid suction section3from the suction side end of the first liquid suction section3. The first liquid α sucked into the first liquid suction section3moves to the discharging side end by the capillary action, the first liquid α is heated by the heating element10at the discharging side end of the first liquid suction section3and is vaporized. Then, the vaporized gas is perspired into the space84in the accommodating section81from the end surface of the first liquid suction section3on the discharging side. Since the first liquid α is vaporized in the first liquid suction section3in this manner, it is possible to suppress the bumping of the first liquid α.

If the boiling point of the first liquid α is higher than the boiling point of the second liquid β, the second liquid β is vaporized at a location close to the end surface on the discharge side of the second liquid suction section2, and the first liquid α is vaporized at a location close to the end surface of the first liquid suction section3on the discharge side. However, if the boiling point of the first liquid α is lower than the boiling point of the second liquid β, and if the temperature is controlled such that the second liquid β is vaporized at a location close to the end surface of the second liquid suction section2on the discharge side, the first liquid suction section3which is more easily heated by the heating element10is excessively heated, the vaporizing region of the first liquid suction section3is not only the discharging side end but is expanded to a more rear portion than the discharging side end, and this may cause the bumping of the first liquid α. Therefore, it is preferable that the boiling point of the first liquid α is higher than the boiling point of the second liquid β.

Gas of the second liquid β vaporized in the second liquid suction section2is perspired in the space84from the discharge side end surface of the second liquid suction section2, gas of the first liquid α vaporized in the first liquid suction section3is perspired in the space84from the discharge side end surface of the first liquid suction section3, and these gases are mixed. This mixture γ is discharged out through the discharge hole82a.

When liquid is being vaporized in this manner, since the controller50feedback controls the heating element10based on the detected temperature of the temperature sensor11, the temperature of the discharging side end of the first liquid suction section3, the vaporizing region of the first liquid α of the first liquid suction section3, the temperature of the discharging side end of the second liquid suction section2, and the vaporizing region of the second liquid β of the second liquid suction section2are controlled such that they fall within desired values and desired range, respectively.

According to the exemplary example, the second liquid suction section2and the first liquid suction section3are concentrically laminated on each other, and the second liquid suction section2and the first liquid suction section3are partitioned by the partition section4. Therefore, in the second liquid suction section2and the first liquid suction section3, the second liquid β and first liquid α are not mixed in the liquid state. Thus, different kinds of liquid are sucked in different regions. For this reason, since it is possible to separately vaporize two kinds of liquid having different boiling points, the two kinds of liquid can stably be vaporized. Since gases stable generated separately are mixed in the space84, the mixture is sent downstream through the discharge hole82a. Thus, the mixture is sent downstream through the discharge hole82aat a stable flow rate. Especially, when the first liquid α is water and second liquid β is methanol, a water vapor reforming device is disposed downstream, and hydrogen can be generated.

Conventionally, if liquids having different boiling points are heated to different temperatures using different heating means, there is a problem that the vaporizer itself is increased in size. According to the vaporizer1, since two kinds of liquid can separately be vaporized using one heating means (heating element10), it is unnecessary to prepare two heating means or vaporizers for vaporizing two kinds of liquid, and it is unnecessary to separately control using two temperature sensors. Therefore, space can be saved, the circuit can be simplified, and cost thereof can be reduced.

The second liquid suction section2is fitted into the first liquid suction section3, and the heating element10is wound around the first liquid suction section3. Therefore, such a temperature distribution that the temperature is increased from the center axis to radially outward is generated. Further, since the second liquid β having low boiling point is sucked into the second liquid suction section2and vaporized, the first liquid α having high boiling point is sucked into the first liquid suction section3and vaporized and thus, the utility efficiency of energy is enhanced, and the second liquid β and first liquid α can efficiently be vaporized.

The shape of the heating element10is not limited to the coil shape, and if the heating element10is disposed on the side surface of the discharging section8, the heating element10may be a thin film heat-generating resistant layer. The heat-generating resistant layer may be a metal oxide or gold (Au). Since the resistivity of gold is varied in accordance with temperature, the heat-generating resistant layer can also function as a temperature sensor. Thus, the temperature sensor11becomes unnecessary, and the wire structure can be simplified.

If the discharging section8is a conductive section, the discharging section8may be coated with an insulative film, and the insulative film may be covered with the heat-generating resistant layer. At that time, if the heat-generating resistant layer is gold, a backing layer such as titanium (Ti) and tantalum (Ta) for enhancing the adhesion with respect to the insulative film, and a heat dispersion preventing layer comprising metal having high melting point such as tungsten for preventing gold from dispersing heat may be laminated between the insulative film and the heat-generating resistant layer in this order.

The second liquid suction section2, the discharging side end of the first liquid suction section3, the accommodating section81and the flange83of the discharging section8, and the heating element10are accommodated in the heat insulation case9. Therefore, the heat loss is small, and heat energy of the heating element10is effectively utilized for vaporizing liquid. Since the suction side ends of the second liquid suction section2and the first liquid suction section3are located outside of the heat insulation case9, a temperature gradient is generated from the suction side end to the discharging side end of the second liquid suction section2, and the temperature of the suction side end of the second liquid suction section2becomes lower than the temperature of the discharging side end thereof. Therefore, the second liquid β sucked by the second liquid suction section2is not vaporized at a location close to the sucking side end surface, and it is possible to prevent gas in the second liquid suction section2from being discharged only from the sucking side end surface, i.e., to prevent gas from flowing reversely. The first liquid α sucked by the first liquid suction section3is not vaporized at a location close to the sucking side end surface, and it is possible to prevent gas from flowing reversely.

Since the temperature sensor11is embedded in the discharging section8, it is possible to precisely measure the temperature near the discharge side end surface of the first liquid suction section3and the temperature near the discharge side end surface of the second liquid suction section2. Further, since the temperature is controlled by the controller50based on the precise detected temperature, it is possible to maintain the temperature near the discharge side end surface of the first liquid suction section3and the temperature near the discharge side end surface of the second liquid suction section2within desired temperature ranges, and it is possible to vaporize stably. Since the heat insulation case9can be divided vertically into the upper case91and the lower case92, it is possible to operate while visually checking, and the assembling operability of the vaporizer1is enhanced.

If the contractile tube5is heated, it is shrunk. Therefore, the adhesion between the outer peripheral surface of the first liquid suction section3and the inner peripheral surface of the contractile tube5is enhanced. Thus, the first liquid α or gas of the first liquid α does not leak from the outer peripheral surface of the first liquid suction section3.

Although the second liquid suction section2and the first liquid suction section3are of the concentric double structure in the exemplary example, a concentric triple structure may by employed by providing additional cylindrical liquid sucking section outside of the first liquid suction section3and by providing the partition section between the cylindrical liquid sucking section and the first liquid suction section3. Further, a concentric multi-layer structure may be employed by providing more liquid sucking sections. In this case, it is preferable that liquid having higher boiling point is supplied to the sucking side end surface of an outer liquid sucking section of the plurality of liquid sucking sections, i.e., to the sucking side end surface of a liquid sucking section closer to the heating element10, and111having higher boiling point is sucked into an outer liquid sucking section, i.e., a liquid sucking section further from the heating element10.

The second liquid suction section2may be divided in a circumferential direction, a partition wall may be interposed between the divided fan-like liquid sucking sections, the partition wall may project from an inner surface of a back surface of the first liquid introducing section7, the space71may be partitioned into a plurality of fan-like spaces by the partition wall, and an introducing hole which is in communication with each fan-like space may be formed in the outer peripheral surface of the first liquid introducing section7.

The second liquid suction section2may be divided into a plurality of liquid sucking sections by a partition wall.

Second Exemplary Example

FIG. 3Ais a rear view of a vaporizer101,FIG. 3Bis a sectional view taken along the cut line B-B inFIG. 3A,FIG. 3Cis a front view of the vaporizer101, andFIG. 3Dis a sectional view taken along the cut line D-D shown inFIG. 3B.

As shown inFIGS. 3A to 3D, a body tube109is formed into a prismatic tube, a back surface opening and a front surface opening of the body tube109are closed, and an internal space is formed in the body tube109. A partition wall104is formed inside of the body tube109. The partition wall104is in parallel to an upper surface and a lower surface of the body tube109. The internal space of the body tube109is partitioned by the partition wall104into vertical two spaces extending from front to rear of the body tube109. The partition wall104is connected to a rear end surface, and inner sides of left and right side surfaces of the body tube109, and is not connected to an inner side of the front end surface of the body tube109. Therefore, the upper space and lower space in the body tube109are in communication with each other at a location close to the front surface, and a space at a location where the upper and lower spaces are connected is designated with a symbol184.

The body tube109is provided at its back surface with a second liquid-introducing opening172into which the second liquid β is introduced, and a first liquid-introducing opening174into which the first liquid α is introduced. The second liquid-introducing opening172and the first liquid-introducing opening174project from the body tube109. An introducing hole173is formed along the center axis of the second liquid-introducing opening172from a tip end of the second liquid-introducing opening172to an inner surface of the body tube109, and the introducing hole173is in communication with a lower space in the body tube109. An introducing hole175is formed along the center axis of the first liquid-introducing opening174from a tip end of the first liquid-introducing opening174to an inner surface of the body tube109, and the introducing hole175is in communication with the upper space in the body tube109.

A second liquid suction section102is charged into the lower space in the body tube109, a first liquid suction section103is charged into the upper space, and the second liquid suction section102and the first liquid suction section103are laminated on each other in the thickness direction with the partition wall104interposed therebetween. The first liquid suction section103and the second liquid suction section102are prismatic core members. The second liquid suction section102and the first liquid suction section103are porous bodies formed with fine spaces therein like the first liquid suction section3and the second liquid suction section2of the first exemplary example, and the second liquid suction section102and the first liquid suction section103can suck liquid.

A rear end surface of the second liquid suction section102(this end surface is called sucking side end surface hereinafter) faces the introducing hole173, and a front end surface of the second liquid suction section102(this end surface is called discharge side end surface hereinafter) faces the space184. A rear end surface of the first liquid suction section103(this end surface is called sucking side end surface hereinafter) faces the introducing hole175, and a front end surface of the first liquid suction section103(this end surface is called discharge side end surface hereinafter) faces the space184.

A heating element110is placed on an upper surface of the body tube109. The heating element110is placed on the body tube109of the first liquid suction section103on the side of the discharging side end. Therefore, the temperatures of the liquid suction sections102and103are gradually increased from the suction side end toward the discharging side end. The first liquid suction section103is closer to the heating element110than the second liquid suction section102. The temperature of the discharging side end of the first liquid suction section3is higher than that of the discharging side end of the second liquid suction section2.

The body tube109, the first liquid-introducing opening174, the second liquid-introducing opening172and the discharging opening182are made of metal (e.g., stainless steel (SUS316)).

Next, the operation of the vaporizer101and the vaporizing method using the vaporizer101will be explained.

If the first liquid α is sent to the introducing hole175of the first liquid-introducing opening174by a pump or the like in a state where the discharging side ends of the first liquid suction section103and the second liquid suction section102are heated by the heating element110, the first liquid α is sucked into the first liquid suction section103from the sucking side end surface of the first liquid suction section103. The first liquid α which penetrates the discharging side end of the first liquid suction section103is vaporized by heat of the heating element110. The vaporized gas is perspired into the space184from the discharge side end surface of the first liquid suction section103.

The first liquid suction section103is closer to the heating element110than the second liquid suction section102, and is interposed between the second liquid suction section102and the heating element110. Therefore, the heating temperature of the heating element110is higher at the discharging side end of the first liquid suction section103than the discharging side end of the second liquid suction section102. Therefore, it is preferable that the boiling point of the first liquid α is higher than the boiling point of the second liquid β.

If the second liquid β is sent to the introducing hole173of the second liquid-introducing opening172, the second liquid β is sucked into the second liquid suction section102from the sucking side end surface of the second liquid suction section102. The second liquid β which penetrates the discharging side end of the second liquid suction section102is vaporized by heat of the heating element110through the first liquid suction section103. The vaporized gas is perspired into the space184from the discharge side end surface of the second liquid suction section102.

The gas of the second liquid β perspired into the space184from the discharge side end surface of the second liquid suction section102and the gas of the first liquid α perspired into the space184from the discharge side end surface of the first liquid suction section103are mixed in the space184. This mixture is discharged out through the discharge hole182a.

According to the exemplary example, the second liquid suction section102and the first liquid suction section103are laminated on each other with the partition wall104interposed therebetween. Therefore, the second liquid suction section102and the first liquid suction section103can independently absorb liquid. Since two kinds of liquid having different boiling points can be vaporized independently, the liquid can be vaporized stably. Since the two kinds of liquid can independently be vaporized using one vaporizer101, it is unnecessary to prepare two vaporizers for vaporizing two kinds of liquid. Therefore, space can be saved as a whole, and cost thereof can be reduced.

The first liquid α having the higher boiling point is sucked by the end of the first liquid suction section103having the higher heating temperature and is vaporized, and the second liquid β having the lower boiling point is vaporized at the end of the second liquid suction section102having the lower heating temperature. Therefore, the utilizing efficiency of energy is enhanced, and the first liquid α and second liquid β can efficiently be vaporized.

The exemplary example employs the double structure in which the partition wall104is interposed between the first liquid suction section103and the second liquid suction section102, and the second liquid suction section102and the first liquid suction section103are superposed on each other. It is also possible to employ such a structure that more partition walls are provided in the body tube109, the space in the body tube109is divided into many spaces from the sucking side end surface to the discharge side end surface of the body tube109, and liquid sucking sections are charged into the respective spaces. In this case, the front end of each partitioning material is separated from the inner side of the front surface of the body tube109so that the vertically divided plurality of spaces are connected to each other through the space184, and introducing holes which are in communication with the vertically divided many spaces are formed in the rear end surface of the body tube109. It is preferable that liquid having higher boiling point is supplied to a sucking side end surface of a liquid sucking section located closer to the heating element110, and liquid having higher boiling point is sucked as approaching the heating element110.

The space in the body tube109is vertically divided by the partition wall104. In addition to this, partition walls which are in parallel to left and right side surfaces of the body tube109may be disposed in the body tube109, and the space in the body tube109may be divided vertically and laterally. In this case, the front end of each partitioning material tries to separate from the inner side of the front surface of the body tube109, the spaces divided into four vertically and laterally are in communication with each other through the space184, and the introducing holes which are in communication with the spaces vertically and laterally divided are formed in the back surface of the body tube109.

When the boiling point of the second liquid β sucked by the second liquid suction section102is higher than the boiling point of the first liquid α sucked by the first liquid suction section103, the heating element110is provided on the lower surface of the body tube109.

The body tube109has thermal conductivity as high as 10 (W·m−1K−1) or higher, and is made of material which is less prone to corrode or deform with respect to the first liquid α or mixture γ (mixture of gas of second liquid β and gas of first liquid α), and is made of metal such as brass and copper.

The shape of the heating element110is not limited to the coil shape. If the heating element110is disposed on the side surface of the body tube109, the heating element110may be a thin film heat-generating resistant layer. The heat-generating resistant layer may be made of metal oxide or gold (Au). Since the resistivity of gold is varied in accordance with temperature, the heat-generating resistant layer can also function as a temperature sensor. Thus, the temperature sensor becomes unnecessary, and the wire structure can be simplified.

If the body tube109is a conductive section, the body tube109may be coated with an insulative film, and the insulative film may be covered with the heat-generating resistant layer. At that time, if the heat-generating resistant layer is gold, a backing layer such as titanium (Ti) and tantalum (Ta) for enhancing the adhesion with respect to the insulative film, and a heat dispersion preventing layer comprising metal having high melting point such as tungsten for preventing gold from dispersing heat may be laminated between the insulative film and the heat-generating resistant layer in this order.

FIG. 4is a block diagram showing the vaporizer1together with cartridges901and902, pumps903and904, a reforming device905, a carbon monoxide eliminating device906, a fuel cell907and a combustor908.

The first liquid-introducing opening72is connected to the pump904, and the pump904is connected to the cartridge902. Water (boiling point: 100° C.) is stored in the cartridge902, and the water is sent to the first liquid-introducing opening72by the pump904. A syringe pump or an electro-osmotic pump may be used as the pump904.

The pump903is connected to the second liquid introducing section13, and the pump903is connected to the cartridge901. Liquid fuel (e.g., methanol (boiling point is 65° C.) or ethanol (boiling point is 78.3° C.) having boiling point lower than that of water is stored in the cartridge901, and the liquid fuel is sent to the partition section4by the pump903. A syringe pump or an electro-osmotic pump may be used as the pump903.

The reforming device905is connected to the discharging opening82of the discharging section8, and a mixture of fuel and water discharged from the vaporizer1is supplied to the reforming device905.

The reforming device905make the fuel and water supplied from the vaporizer1react with each other by catalysis, thereby producing hydrogen gas and the like. In the reforming device905, a very small quantity of carbon monoxide is also produced. When the liquid fuel stored in the cartridge901is methanol, reaction as shown in the following equations (1) and (2) occurs in the reforming device905.
CH3OH+H2O→3H2+CO2(1)
2CH3OH+H2O→5H2+CO+CO2(2)

The mixture in a product produced by the reforming device905is supplied to the carbon monoxide eliminating device906, and air is supplied to the carbon monoxide eliminating device906by an air pump. In the carbon monoxide eliminating device906, carbon monoxide in the mixture is selected by a catalyst, the carbon monoxide is subject to oxidation with higher priority, and hydrogen is not subject to oxidation.

The fuel cell907includes a fuel pole907acarrying catalyst fine particles, an air pole907bcarrying catalyst fine particles, and an electrolyte film907cinterposed between the fuel pole907aand the air pole907b. A mixture is supplied to the fuel pole907afrom the carbon monoxide eliminating device906, and air is supplied to the air pole907bby an air pump. Ion is produced by one of the fuel pole907aand the air pole907b, the ion penetrates the electrolyte film907c, water is produced by the other pole and with this, electricity is generated between the fuel pole907aand the air pole907b. When a hydrogen ion can penetrate the electrolyte film907c(e.g., a solid high polymer electrolyte film), a reaction as shown in the following equation (3) occurs in the fuel pole907a, and a reaction as show in the following equation (4) occurs in the air pole907b.
H2→2H++2e−(3)
2H++½O2+2e−→H2O  (4)

Offgas including excessive hydrogen gas which does not react by the fuel pole907ais supplied to the combustor908, and air is supplied to the combustor908by the air pump. In the combustor908, oxygen in the air and unreacted hydrogen react with each other through a catalyst, and combustion heat is generated. The combustion heat is used for reaction between the reforming device905and the carbon monoxide eliminating device906.

The entire system shown inFIG. 4is provided in electronic equipment such as a notebook personal computer, a PDA, an electronic notepad, a digital camera, a cellular phone, a watch, a register and a projector. The fuel cell907is used as a power supply of the electronic equipment.

When the vaporizer101shown inFIGS. 3A to 3Dis applied to the system shown inFIG. 4, the first liquid-introducing opening174is connected to the pump904, the second liquid-introducing opening172is connected to the pump903, water is supplied from the cartridge902to the first liquid-introducing opening174, and liquid fuel is supplied from the cartridge901to the second liquid-introducing opening172.

When the boiling point of the fuel is higher than that of water, fuel is introduced into the first liquid-introducing opening72and water is introduced into the second liquid introducing section13.

Experiments were conducted. In the experiments, a vaporizer501as shown inFIG. 5was used as a comparative example. In the vaporizer501, the integral member comprising the partition section4, the first liquid suction section3and the second liquid suction section2shown inFIG. 1is replaced by one cylindrical liquid suction section502, the elastic tube6is elongated, and the first liquid introducing section7is removed. Except these points, the vaporizer501is the same as the vaporizer1, a pump is connected to a flow rate meter, the flow rate meter is connected to the elastic tube6, and the discharge hole82aof the discharging opening82is opened. Conditions of the liquid suction section502are as follows:

(a) The liquid suction section502(columnar body): a pore ratio is 41%, a particle diameter is 3 μm, a diameter is 1.5 mm, a length is 10.0 mm, and 2 mm of tip end is heated to 130° C. by the heating element10through the accommodating section81, and

(b) The discharging section8: a material is brass, and an inner diameter of the discharge hole82ais 0.5 mm.

In a state where the heating element10was not heated, 60 wt % of methanol water solution was sent to the elastic tube6through a flow rate meter by a pump (electro-osmotic pump), and the flow rate of the methanol water solution was measured by the flow rate meter. A result of measurement of the flow rate is shown inFIG. 6. A set value of the flow rate of the pump was 60 μl/min.

In a state where the heating element10was heated to 130° C., 60 wt % of methanol water solution was sent to the elastic tube6through the flow rate meter by the pump (electro-osmotic pump), and the flow rate of the methanol water solution was measured by the flow rate meter. A result of measurement of the flow rate is shown inFIG. 7. As apparent fromFIG. 7, in the case of the methanol water solution having no azeotrope point, peaks of the flow rate were generated frequently for a short time, and pulsation was generated in the methanol water solution. Further, variation in the flow rate was also large. One cycle of pulsation is time from a peak of the flow rate to a next peak of the flow rate inFIG. 7. Variation in flow rate of about 10 μl/min was found in a short term at the maximum.

In the vaporizer1having the structure shown inFIG. 1, in a state where the heating element10was heated to 130° C., a liquid-sending amount when pure water was sent to the first liquid introducing section7by a pump (electro-osmotic pump) and a liquid-sending amount when methanol was sent to the second liquid introducing section13by a pump (syringe pump) are shown inFIGS. 8 and 9, respectively. Conditions of the vaporizer1are set as follows:

(a) Second liquid suction section2(columnar body): a pore ration is 41%, a diameter is 1.5 mm, and a length 20.0 mm,

(b) Partition section4(cylindrical tube): a material is SUS316, an inner diameter is 1.5 mm, a thickness is 0.1 mm, and a length is 20.0 mm,

(c) First liquid suction section3(cylindrical body): a pore ratio is 41%, an outer diameter is 2.3 mm, a length is 10.0 mm, and 2 mm of tip end is heated to 130° C. by the heating element10through the accommodating section81, and

As apparent fromFIG. 8, since there is only pure water in the first liquid suction section3, the flow rate is not abruptly varied and liquid can be sent stably.

As apparent fromFIG. 9, since there is only methanol in the second liquid suction section2, the flow rate is not abruptly varied and liquid can be sent stably.

InFIG. 9, the reason why the flow rate was increased gradually from 0 second to 110 seconds was due to characteristics of the syringe pump.

As can be found from the above experiments, if the methanol water solution having no azeotrope boiling point was vaporized, a large pulsation was generated, but no large pulsation was generated in the case of water alone and methanol alone. Therefore, if two kinds of liquid are supplied to the vaporizer1and the vaporizer101and vaporized independently like the vaporizer1and vaporizer101of the above exemplary example, two kinds of liquid can stably be vaporized.

FIG. 10shows data of a temperature gradient when water having relatively high boiling point was supplied to the first liquid suction section3and methanol having relatively low boiling point was supplied to the second liquid suction section2in a state where the heating element10was heated to 130° C. in the vaporizer1. It can be found that since the discharging side ends of the first liquid suction section3and the second liquid suction section2are relatively equally heated, temperatures of both liquids reach the boiling points in a wide range and water and methanol can be vaporized excellently.

FIG. 11shows data of a temperature gradient when methanol having relatively low boiling point was supplied to the first liquid suction section3, and water having relatively high boiling point was supplied to the second liquid suction section2in a state where the heating element10was heated to 130° C. in the vaporizer1. In the first liquid suction section3, methanol is vaporized excessively largely beyond the boiling point, but at the discharging side end of the second liquid suction section2, sufficient heat is not transferred due to an endothermic phenomenon caused by vaporization of methanol in the first liquid suction section3, a region where the temperature reaches the boiling point of water is small, and the vaporization amount of water is not enough.

Another exemplary example for carrying out the present invention will be explained using drawings. Although various limitations which are preferable for carrying out the invention are proposed in the following exemplary examples, the scopes of the invention are not limited to the exemplary examples and illustrated examples.

FIG. 12is a sectional view of a vaporizer201.FIG. 13is an exploded perspective view showing an upper surface, a front surface and a right surface.FIG. 14is an exploded perspective view showing an upper surface, a back surface and a left surface.

As shown inFIGS. 12 to 14, the vaporizer201includes a liquid suction section202which liquid can penetrate, a contractile tube203having a member which contracts if it is heated or an elastic member such as a heat-resistant rubber having no or a small amount of double bond in a main chain of a molecular structure, a heat radiating section204which is in contact with a rear end of the liquid suction section202, a heat transfer section205which transfers heat to the liquid suction section202, a heat insulation case206which has a thermal conductivity lower than that of the heat transfer section205and which prevents heat of a front portion of the heated liquid suction section202from propagating to outside of the vaporizer201, a heating section207for heating the liquid suction section202, a temperature sensor208which measures the temperature of the liquid suction section202through the heat transfer section205, and a discharging section209which discharges gas discharged by the liquid suction section202.

The liquid suction section202is a core member formed into a rod-like shape, more specifically, a columnar shape. The liquid suction section202has such characteristics to take in liquid which comes into contact with the suction side end202band sucks the same to a discharging side end202aby capillary action. More concretely, the liquid suction section202is a porous body provided with a fine space therein, the liquid suction section202can absorb liquid, and the liquid suction section202is made of material which does not melt and is not deteriorated even if it is heated by the heating section207. The liquid suction section202may be a section obtained by solidifying an inorganic fiber or organic fiber using bonding material (e.g., epoxy resin), may be a section obtained by sintering inorganic powder, may be a section obtained by solidifying inorganic powder using bonding material (e.g., epoxy resin), or may be a porous mixture body of graphite and glassy carbon. The liquid suction section202may be a section obtained by binding a large number of thread materials comprising inorganic fiber or organic fiber using bonding material. For example, an acrylic fiber flux core may be used as the liquid suction section202.

A center portion of the liquid suction section202is inserted into the contractile tube203so that the discharging side end202aand the suction side end202bare exposed, and an outer peripheral surface of the center portion of the liquid suction section202is in intimate contact with the contractile tube203. The contractile tube203is shorter than the liquid suction section202, and both ends202aand202bof the liquid suction section202are located at positions projecting from ends of the contractile tube203.

Since liquid in the contractile tube203does not penetrate the liquid suction section202, liquid does not leak outside from the contractile tube203. The contractile tube203has preferably elastomer properties and has contractile. It is preferable that in a natural state where the liquid suction section202is not inserted into the contractile tube203, the inner diameter of the contractile tube203is smaller than a diameter of the liquid suction section202, and if the liquid suction section202is inserted, and the contractile tube203is increased in diameter in view of adhesion between the liquid suction section202and the contractile tube203and in view of liquid leakage prevention.

A portion of the liquid suction section202from its intermediate portion to the suction side end202bis fitted into the tube-like heat radiating section204. A portion of the liquid suction section202from its intermediate portion to the discharging side end202ais fitted into the heat transfer section205. There exists a gap between the heat radiating section204and the heat transfer section205so that they do not come into contact with each other.

A portion of the contractile tube203is also fitted into the heat radiating section204in a state where the liquid suction section202is inserted. An outer peripheral surface of a portion of the liquid suction section202projecting from the contractile tube203is in contact with an inner surface of the heat radiating section204. For example, the heat radiating section204is made of material having a high thermal conductivity such as gold (thermal conductivity is 315 W/m·K), silver (thermal conductivity is 427 W/m·K), copper (thermal conductivity is 398 W/m·K), aluminum (thermal conductivity is 237 W/m·K), ceramic and carbon fiber. The thermal conductivity of the heat radiating section204is higher than those of the liquid suction section202, the contractile tube203and the heat insulation case206. It is preferable that the heat radiating section204has a tube structure, apparent volume is not too large, an area of a radiation surface is greater, and an outer surface of the heat radiating section204is formed with a groove.

The heat transfer section205has a thermal conductivity higher than that of the liquid suction section202. The heat transfer section205is a cylinder in which the discharging side end202aof the liquid suction section202is accommodated such that the discharging side end202acomes into intimate contact with the heat transfer section205. The heat transfer section205is integrally formed with the discharging section209having a portion exposed from the heat insulation case206, and a flange53projecting from an outer edge of a joint between the heat transfer section205and the discharging section209. The discharging section209projects from a flange surface of the flange53. The discharging section209is provided with a discharge hole55. The liquid suction section202inserted into the heat transfer section205vaporizes the inside liquid by heat of the heating section207and the generated gas is discharged from the discharge hole55. The outer diameter of the discharging section209is smaller than that of the heat transfer section205, and the inner diameter (diameter of the discharge hole55) of the discharging section209is smaller than the inner diameter of the heat transfer section205. It is preferable that the heat transfer section205includes material which can efficiently propagate heat of the heating section207to the liquid suction section202like metal having thermal conductivity higher than those of the contractile tube203, the heat insulation case206and the liquid suction section202(e.g., brass Cu 70%, Zn 30%, thermal conductivity 106 W/m·K), and which can facilitate the vaporization of liquid.

The liquid suction section202is inserted into the heat transfer section205, a portion of the contractile tube203is also inserted into the heat transfer section205, and an outer peripheral surface of a portion of the liquid suction section202projecting from the contractile tube203is in contact with an inner surface of the heat transfer section205.

The heating section207which is a heater such as a heating coil is wound around an outer periphery of the heat transfer section205, and the heating section207and the heat transfer section205are in contact with each other. The heating section207comprises an electric heating material, and generates heat by electricity. A nickel-cobalt wire may be used as the heating section207. When the heat transfer section205is a conductive member and the heating section207is a heating resistor such as an electric heating material, it is preferable that an insulative film (not shown) is interposed between the heat transfer section205and the heating section207so that applied voltage is efficiently divided to the heating section207and heated. However, if a portion of the heat transfer section205exposed from the heat insulation case206is sufficiently small, the insulative film may not be provided. The heating section207is coated with ceramic adhesive56, and the heating section207is fixed to the heat transfer section205by the ceramic adhesive56.

An insertion hole54is formed in the flange53in the radial direction. The insertion hole54does not reach internal spaces of the heat transfer section205and the discharging section209, and a bottom of the insertion hole54is located near an end surface of the liquid suction section202. Insulative adhesive is charged into the insertion hole54in a state where the temperature sensor208is inserted, and the temperature sensor208is coated with insulative adhesive. Therefore, even if the heat transfer section205is made of conductive member, the temperature sensor208and the heat transfer section205are electrically insulated from each other. The temperature sensor208is located near the end surface of the liquid suction section202and with this, the temperature sensor208is embedded into the flange53. The temperature sensor208is a thermocouple, a thermistor or a resistance thermometer bulb. The temperature sensor208detects a temperature in accordance with heat of the heating section207transmitted through the heat transfer section205or an insulative adhesive.

If the heating element7is heated, liquid which penetrated into the liquid suction section202by heat propagated from the heating element7to the heat transfer section205is vaporized and is discharged out from the discharge hole55.

The heat insulation case206covers front portions of the heating section207and the liquid suction section202so that heat of the heating section207and the front portion of the liquid suction section202heated by the heating section207is not released outside. The heat transfer section205and the flange53are accommodated in the heat insulation case206, and the heating section207is also accommodated in the heat insulation case206. The heat radiating section204is located outside of the heat insulation case206.

If the entire liquid suction section202is equally heated, liquid is vaporized from the suction side end202bof the liquid suction section202. These bubbles causes steric hindrance, and hinders the penetration of liquid through the liquid suction section202, and an amount of gas discharged from the discharging section209becomes instable.

Since a rear portion of the liquid suction section202is not covered with the heat insulation case206, heat is easily released therefrom as compared with a portion of the liquid suction section202covered with the heat insulation case206. Further, heat of the liquid suction section202is propagated to the heat radiating section204and is discharged out from the surface of the heat radiating section204. Therefore, the temperature of the rear portion of the liquid suction section202does not reach the boiling point of liquid in the liquid suction section202.

The heating section207heats the front portion of the liquid suction section202such that the temperature thereof reaches the boiling point of liquid which penetrates the liquid suction section202. Therefore, if gas vaporized in the liquid suction section202is discharged out from the discharging side end202a, liquid charged into the rear portion of the liquid suction section202spontaneously moves forward of the liquid suction section202by the capillary action of the liquid suction section202.

An upper case61and a lower case62of the heat insulation case206are combined with each other, thereby forming an accommodation space in the heat insulation case206. The upper case61and the lower case62are made of heat insulator having thermal conductivity lower than that of the heat transfer section205such as a ceramic obtained by sintering titanium oxide, potassium oxide, calcium oxide, silicon oxide, or PES (sulf-polyether), or engineering plastic such as styrenefoam and urethanefoam, and a glass.

Fan-like recesses are formed in a lower edge of a front surface of the upper case61and an upper edge of a front surface of the lower case62, the upper case61and the lower case62are coupled to each other and as a result, the recesses are coupled to each other and a through hole63is formed therebetween. The discharging section209is fitted into the through hole63, and the discharging section209projects from a front surface of the heat insulation case206. The flange53of the heat transfer section205is in contact with an inner surface of the front surface of the heat insulation case206for fixing a position. To enhance the heat insulation, a space may be provided between the flange53and the inner surface of the front surface of the heat insulation case9. If a groove is formed in a surface of the flange53opposed to the heat insulation case9, the flange53and the heat insulation case9abut against each other so that alignment can be carried out, a gap having a low thermal conductivity for insulating heat can be formed by this groove, and this enhances the heat insulation effect.

Fan-like recesses are formed in a lower edge of a back surface of the upper case61and an upper edge of a back surface of the lower case62, the upper case61and the lower case62are coupled to each other and as a result, the recesses are coupled to each other and a through hole64is formed therebetween. The contractile tube203and the liquid suction section202are fitted into the through hole64. The contractile tube203and the wall surface of the through hole64come into intimate contact with each other, and a gap between the wall surface of the through hole64and the outer peripheral surface of the liquid suction section202is sealed by the contractile tube203.

Wire-through holes65to67pass through an upper surface of the upper case61, and grooves65ato67awhich are in communication from the wire-through holes65to67to the back surface of the upper case61are formed in the upper surface of the upper case61. A wire51of the temperature sensor208is inserted through the wire-through hole65, the wire51is bent and laid in the groove65a. Similarly, wires271and272of both ends of the heating section207are inserted through the wire-through holes66and67, the wires271and272are bent and laid in the grooves66aand67a.

The temperature sensor208is connected to a controller250through the wire51, and the heating section207is also connected to the controller250through the wires271and272. A signal indicative of the detected temperature of the temperature sensor208is input to the controller250, and the controller250controls the heating section207such that the temperatures of the heat transfer section205and of the discharging side ends202aof the liquid suction section202become desired temperatures. More specifically, when the detected temperature of the temperature sensor208becomes higher than an upper threshold value, the controller250reduces or cuts off the electricity to be supplied to the heating section207, and when the detected temperature of the temperature sensor208becomes lower than a lower threshold value (lower threshold value<upper threshold value), the controller250increases or tuns on the electricity to be supplied to the heating section207, and when the detected temperature of the temperature sensor208is higher than the lower threshold value and lower than the upper threshold value, the controller250maintains the electricity to be supplied to the heating section207.

Next, the operation of the vaporizer201and the vaporizing method using the vaporizer201will be explained.

If voltage is applied to the heating section207, the heating section207is heated, and a member accommodated in the heat insulation case206is heated. In this state, if liquid is sent by a pump or the like into the heat radiating section204which also functions as a supply tube of liquid, the liquid in the heat radiating section204is sucked into the liquid suction section202from the suction side end202bof the liquid suction section202. The liquid sucked into the liquid suction section202moves toward the discharging side end202aon the opposite side by the capillary action. The heating temperature at a portion inside of the heating element7is reduced as separating from the heating element7. Therefore, in a state where the detected temperature of the temperature sensor208is higher than the lower threshold value and lower than the upper threshold value, the temperature is set such that the temperature reaches the boiling point of the liquid on the side of the discharging side end202aof the liquid suction section202and the temperature is less than the boiling point of the liquid at the suction side end202b. Thus, liquid is vaporized mainly in the liquid suction section202on the side of the discharging side end202a. The gas is discharged out from the discharging side end202aof the liquid suction section202through the discharge hole55of the discharging section209. If liquid is vaporized and discharged out, liquid is continuously charged into the discharging side end202aof the liquid suction section202from the suction side end202bby the capillary action, and the vaporization of liquid is continuously carried out.

When liquid is being vaporized, the controller250feedback controls the heating section207based on the detected temperature of the temperature sensor208. Therefore, the temperature of the heat transfer section205and the temperature of the liquid suction section202on the side of the discharging side end202acan successively be managed and the temperatures can be kept in desired ranges with time.

According to this exemplary example, as described above, the discharging side end of the liquid suction section202, the heat transfer section205, the flange53and the heating section207are accommodated in the heat insulation case206. Therefore, the heat loss is small, and the thermal energy of the heating section207is effectively utilized for the vaporization of liquid. If the temperature of the front portion of the liquid suction section202becomes instable by an external reason and the liquid suction section202is excessively heated, the vaporization is excessively facilitated in the liquid suction section202and this may cause the bumping. According to the exemplary example, however, since the heat of the front portion of the liquid suction section202is stored by the heat insulation case206, the heat retention ability is high, influence caused by environment such as outside temperature of the vaporizer201is small and thus, the temperature control for vaporizing liquid stably can be carried out easily, and excessive heating can easily be prevented.

Since the suction side end of the liquid suction section202is located outside of the heat insulation case206, the temperature gradient is generated from the suction side end202bof the liquid suction section202to the discharging side end202a, and the temperature of the suction side end202bof the liquid suction section202becomes lower than that of the discharging side end202a. Especially, since the suction side end of the liquid suction section202comes into contact with the heat radiating section204having high heat conduction and the heat radiating section204is located outside of the heat insulation case206, heat of the suction side end of the liquid suction section202is prone to be radiated from the heat radiating section204naturally.

If the all gas which was excessively generated in the liquid suction section202due to excessive heating can not be discharged out from the discharging side end202aand a portion thereof is discharged into the heat radiating section204from the surface of the suction side end202b, the gas locally exists as bubbles such as to cover at least a portion of the suction side end202bby capillary action of the liquid suction section202and driving force of the pump which sends liquid to the liquid suction section202, and the bubbles causes steric hindrance, and reduces a taking-in area (contact area) of liquid of the suction side end202bof the liquid suction section202. Therefore, the amount of liquid penetrating the liquid suction section202is at least temporarily reduced and becomes instable. At that time, the amount of liquid in the liquid suction section202is reduced and liquid is excessively heated. Immediately after that, bubbles enter the liquid suction section202from the surface of the suction side end202b. If the bubbles flow in the liquid suction section202, since the bubbles have viscosity lower than that of the liquid, the flow velocity is temporarily increased, and liquid which flows at a dash bumps at the liquid suction section202.

In the embodiment, however, the heat radiating section204efficiently discharges heat so that the temperature of the rear portion of the liquid suction section202can be kept lower than that of the front portion and thus, the gas is less prone to be heated excessively, the amount of vaporization is remarkably smaller than that of the front portion. Therefore, gas generated in the liquid suction section202does not reversely flow and gas is not discharged out toward the heat radiating section204from the suction side end202balmost at all. For this reason, it is possible to prevent the rear portion of the liquid suction section202from being excessively heated, the amount of liquid penetrating the liquid suction section202can be stabilized, and the amount of gas discharged from the discharging section209can be stabilized. If a sufficient amount of liquid is continuously supplied into the liquid suction section202, even if a small amount of bubbles is generated in the suction side end202b, the bubbles are cooled and liquefied by liquid having lower temperature or the heat radiating section204. Thus, the problem of the steric hindrance can swiftly be solved, and the variation in flow rate caused by bumping can be reduced.

Since it is possible to effectively radiate heat by the heat radiating section204, it is unnecessary to elongate the liquid suction section202in the longitudinal direction to suppress the reverse flow of gas, or to increase the radiation area. Thus, the vaporizer201can be reduced in size.

Since the temperature sensor208is embedded in the flange53, the temperature near the discharge side end surface of the liquid suction section202can precisely be measured. Since the controller250controls the temperature in accordance with the precise detected temperature, the temperature near the discharge side end surface of the liquid suction section202can be kept at constant level between the lower threshold value and upper threshold value, and stable vaporization can be carried out. Further, since the heat insulation case206can vertically be divided into the upper case61and the lower case62, it is possible to operate while visually checking, and the assembling operability of the vaporizer201is enhanced.

Since the contractile tube203contracts if it is heated, the adhesion between the outer peripheral surface of the liquid suction section202and the inner peripheral surface of the contractile tube203is enhanced. Thus, gas does not inject from the outer peripheral surface of the liquid suction section202.

In this invention, the temperature gradient is provided between the discharging side end and the suction side end of the liquid sucking section, thereby suppressing the bumping of liquid.

The present invention is not limited to the exemplary example, and various improvements and changes of design may be made within a range not departing from the subject matter of the invention.

For example, the heat radiating section204may be cooled by air by creating forced convection around the heat radiating section204by a fan or the like, and heat of the suction side end of the liquid suction section202may be radiated from the heat radiating section204. The heat radiating section204may be cooled by water. When the heat radiating section204is cooled naturally, by air or by water, the outer surface of the heat radiating section204may be provided with bumps and dips, a fin may be projected, thereby increasing a surface area of the heat radiating section204and enhancing the radiating efficiency of the heat radiating section204.

The heating section207may be a ceramic heater instead of the heating coil, or both the heating coil and ceramics heater may be used.

If the outer peripheral surface of the liquid suction section202is covered so that liquid or gas seeps through the outer peripheral surface of the liquid suction section202, the contractile tube203may be omitted. Further, as the contractile tube203, the liquid suction section202may be inserted into a double tube comprising a rubber elastic tube and a thermal contractile tube.

Like a vaporizer201A of a modification shown inFIG. 15, the temperature sensor208may be omitted. Since the vaporizer201A is not provided with the temperature sensor208, it is unnecessary to form the insertion hole54in the flange53and to form the wire-through hole65and the groove65ain the upper case61. The vaporizer201A shown inFIG. 15is the same as the vaporizer201shown inFIG. 12except that the temperature sensor208, the insertion hole54and the wire-through hole65are omitted. Therefore, members of the vaporizer201A corresponding to those of the vaporizer201are designated with the same symbols. In the vaporizer201A having such a structure, the heating section207may also function as a temperature sensor as a heating resistor whose resistance characteristics are varied depending upon the temperature. Gold (Au) and alloy including gold are preferable because displacement of resistivity of the heating resistor with respect to the temperature displacement is sufficiently large, and such metals are strong against deterioration such as oxidation and corrosion, and a laminated structure comprising a heating resistor including gold and the conductive film is also preferable. When heating element heat transfer section205is conductive, the heat transfer section205is coated with an insulative film and the insulative film is coated with a heat-generating resistant layer. If the heat-generating resistant layer includes gold, a backing layer such as titanium (Ti) and tantalum (Ta) for enhancing adhesion with respect to the insulative film, and a heat dispersion preventing layer made of metal having high melting point such as a tungsten (W) for suppressing heat dispersion of gold may be laminated between the insulative film and the heat-generating resistant layer in this order.

FIG. 16is a block diagram showing the vaporizer201(or vaporizer201A) together with a cartridge301, a reforming device303, a carbon monoxide eliminating device304, a fuel cell105and a combustor306.

A pump302is connected to the heat radiating section204, and the pump302is connected to the cartridge301. Water and liquid fuel (e.g., methanol, ethanol, dimethyl ether) are stored in the cartridge301in the mixed state or separately, and mixture of liquid fuel and water is sent to the heat radiating section204by the pump302. A syringe pump or an electro-osmotic pump may be used as the pump302′. The reforming device303is connected to the discharging section209, and mixture of fuel and water discharged from the vaporizer201is supplied to the reforming device303.

The reforming device303makes fuel and water of the mixture supplied from the vaporizer201react with each other through catalyst to generate hydrogen gas. A very small amount of carbon monoxide is also produced in the reforming device303. When liquid fuel stored in the cartridge301is methanol, the following reaction occurs in the reforming device303as shown in the following equations (1) and (2).
CH3OH+H2O→3H2+CO2(1)
2CH3OH+H2O→5H2+CO+CO2(2)

A mixture of product produced by the reforming device303is supplied to the carbon monoxide eliminating device304, and air is supplied to the carbon monoxide eliminating device304by an air pump. In the carbon monoxide eliminating device304, carbon monoxide in the mixture is selected by a catalyst, the carbon monoxide is subject to oxidation with higher priority, and hydrogen is not subject to oxidation.

The fuel cell305includes a fuel pole305acarrying catalyst fine particles, an air pole305bcarrying catalyst fine particles, and an electrolyte film305cinterposed between the fuel pole305aand the air pole305b. A mixture is supplied to the fuel pole305afrom the carbon monoxide eliminating device304, and air is supplied to the air pole305bby an air pump. Ion is produced by one of the fuel pole305aand the air pole305b, the ion penetrates the electrolyte film305c, water is produced by the other pole and with this, electricity is generated between the fuel pole305aand the air pole305b. When a hydrogen ion can penetrate the electrolyte film305c(e.g., a solid high polymer electrolyte film), a reaction as shown in the following equation (3) occurs in the fuel pole305a, and a reaction as show in the following equation (4) occurs in the air pole305b.
H2→2H++2e−(3)
2H++½O2+2e−→H2O  (4)

Offgas including excessive hydrogen gas which does not react by the fuel pole305ais supplied to the combustor306, and air is supplied to the combustor306by the air pump. In the combustor306, oxygen in the air and unreacted hydrogen react with each other through a catalyst, and combustion heat is generated. The combustion heat is used for reaction between the reforming device303and the carbon monoxide eliminating device304.

The present invention will be explained more concretely by way of an embodiment and a comparative example.

In the embodiment, the vaporizer201as shown inFIGS. 12 to 14was used. Conditions of the liquid suction section202, the heat radiating section204, the heat transfer section205(integral type comprising the discharging section209and the flange53) and the heat insulation case206are as follows:

(a) Liquid suction section202: silicon carbide, a diameter is 1.5 mm, and a length is 10 mm,

(b) Heat radiating section204: aluminum (A1080), an inner diameter is 1.5 mm, an outer diameter is 2.5 mm, and a length is 15 mm,

(c) Heat transfer section205: brass, a superposing length of the liquid suction section202and the heating section207in the longitudinal direction is 2 mm, an inner diameter is 1.5 mm, and an outer diameter is 2.5 mm, and

(d) Heat insulation case206: PEEK (polyether ether ketone) and a diameter of a lower portion is 7 mm.

In the comparative example, the heat radiating section204of the vaporizer201was replaced by an elastic tube material having low thermal conductivity such as a silicon tube, and other conditions are the same as those of the embodiment.

In any of the embodiment and the comparative example, 60 wt % of methanol water solution was sent to the heat radiating section204through a flow rate meter by an electro-osmotic pump (tube material having low thermal conductivity in the case of the comparative example), a flow rate of the methanol water solution was measured by the flow rate meter, and the temperature near the suction side end202bof the liquid suction section202was measured by a K-type sheath thermocouple. Here, in the embodiment and the comparative example, methanol water solution was supplied while keeping its heated state by the heating section207. InFIG. 17, it can be found that the flow rate is lowered immediately before the measured flow rate is largely increased and the temperature rises. This is because that bubbles were generated on the side of the suction side end202b, steric hindrance was caused, flow toward the liquid suction section202was stopped, and the liquid suction section202was temporarily heated excessively. Immediately after that, if the bubbles enter the liquid suction section202, the flow rate is temporarily increased due to the low viscosity of the bubbles, a large amount of liquid which flowed into the liquid suction section202is vaporized and bumping is caused.

FIG. 17shows a result of the comparative example andFIG. 18shows a result of the embodiment. As apparent fromFIGS. 17 and 18, the temperature near the sucking side end surface of the liquid suction section202in the embodiment is lower than that of the comparative example.

For this reason, large pulsation (variation in flow rate and about 30 μl/min) was prone to be generated in the supplied liquid, and the peaks of the flow rate of the supplied liquid was generated about three times for about 400 seconds.

In the embodiment, there is no abrupt rise in temperature, pulsation is less prone to be generated in the supplied liquid, and a peak of the flow rate of the supplied liquid was generated only once for about 780 seconds, an interval between the bumpings (variation in flow rate, and less than 15 μl/min) and variation if flow rate are suppressed to low level. Almost no temporarily drop of flow rate was generated by bubbles unlike the comparative example and thus, a case in which liquid abruptly flows into the liquid suction section202immediately after that and bumping is generate is suppressed. It was found that in the embodiment, liquid supplied to the vaporizer201and gas discharged from the vaporizer201flow stably as compared with the comparative example.

The entire disclosure of Japanese Patent Application No. 2006-43708 filed on Feb. 21, 2006 including specification, claims, drawings and abstract, and the entire disclosure of Japanese Patent Application No. 2006-72227 filed on Mar. 16, 2006 including specification, claims, drawings and abstract are incorporated herein by reference in there entireties.