1. Technical field
The present invention relates to a humidifier provided in an air supply line supplying air to a fuel cell.
2. Related art
A fuel cell uses hydrogen gas as a fuel and allows hydrogen gas and oxygen gas to react with each other to generate electricity. The fuel cell receives attention in view of global environmental protection because exhaust gas is not generated for generating electricity. In recent years, attempts have been made to put the fuel cell to practical use as a power source of an automobile.
A vehicle such as an automobile mounts a fuel cell system including the fuel cell. An air supply line supplying air including oxygen gas is connected to the fuel cell, and a humidifier is disposed on the air supply line. The humidifier collects moisture contained in off-gas discharged from the fuel cell, air is humidified using the collected moisture, and the humidified air is supplied to the fuel cell.
Japanese Patent Application Laid-open No. 2002-66265 and Japanese Patent Application Laid-open No. 2003-265933 disclose conventional humidifiers. In the conventional humidifier, a plurality of hollow-fiber membrane modules is disposed. Each hollow-fiber membrane module has a vent pipe and a hollow-fiber membrane is accommodated in the vent pipe. A plurality of circular vent holes for introducing air humidified and a plurality of circular vent holes for discharging humidified air are formed along an outer periphery of theventpipe. The plurality of air-introducing vent holes are formed in one end of the vent pipe straightly along the circumferential direction of the vent pipe. The plurality of humidified air vent holes are formed in the one end of the vent pipe along the circumferential direction of the vent pipe on the same circumference. A distributor is formed on an outer periphery of each vent formed straightly along the circumferential direction of the vent pipe, and a gas conduit is connected to the distributor. An area of an opening of the vent hole closest to the gas conduit is the smallest, and a vent hole which is further from the gas conduit has greater opening area. By changing the area of the opening of the vent hole in accordance with distance from the gas conduit in this manner, gas can be introduced to the outside of the hollow-fiber membrane which is far from the gas conduit.
In the conventional humidifier, the pitches between the vent holes are equal to each other, distances between the vent holes is different. When the distances between the vent holes are different, a compression force and a tensile stress applied in the axial direction of the vent pipe are varied, there is an adverse possibility that the vent pipe is buckled or deformed between the vent holes. When the vent pipe is buckled or deformed between the vent holes, gas is leaked or gas is unevenly distributed, the hollow-fiber membrane is damaged, the humidifying performance of the humidifier is largely deteriorated, and the lifetime of the humidifier is shortened.
In the conventional humidifier, when the opening area of each the vent hole formed in the vent pipe is to be changed, the width of the vent hole in the circumferential direction of the vent pipe and the length of the vent hole in the axial direction are changed, and there exists no uniformity. It is difficult to form vent holes having various opening areas in the vent pipe, and the producing method of the vent pipe is complicated in a designing point of view.
The present invention has been achieved in order to solve the above problems. That is, a humidifier of the invention has a hollow-fiber membrane module comprising a cylindrical gas vent pipe, a permeable hollow-fiber membrane accommodated in the vent pipe, and a first distributing mechanism disposed in the vent pipe. The first distributing mechanism includes a plurality of vent holes formed along an outer periphery of the vent pipe, a distributor covering the vent holes, a gas conduit communicating with the distributor, and a connection hole connecting the gas conduit and the vent holes to each other. Widths of the vent holes in a circumferential direction of the vent pipe are equal to each other, and quantities of flow of gas flowing from the vent holes equal to each other.
Humidifiers of embodiments of the present invention will be explained with reference to FIGS. 1 to
In the first embodiment, a humidifier disposed in a fuel cell system mounted in a fuel cell vehicle will be explained based on FIGS. 1 to 5.
As shown in
The utility supply system (Ls) includes a fuel supply system and an oxidizer supply system. The fuel supply system includes a fuel supply line (Lf) supplying fuel to the fuel cell 2. The oxidizer supply system includes an oxidizer supply line (La) supplying oxidizer gas (air) to the fuel cell 2.
A humidifier 3 is disposed in the oxidizer supply line La of the fuel cell system 1. The humidifier 3 is connected to a gas inlet pipe 4 connected to a compressor (not shown) and to a gas outlet pipe 5 connected to the fuel cell 2.
The off-gas processing system includes an off-gas exhaust line (Ld) and an off-gas return line (Lr). The off-gas exhaust line (Ld) includes an off-gas inlet pipe 6 connecting the fuel cell 2 and the humidifier 3 to each other, and an off-gas outlet pipe 7 connected to the humidifier 3. A combustor 8 and a heat exchanger 9 are disposed in the off-gas outlet pipe 7.
As shown in
In a body 3a of the humidifier 3, two hollow-fiber membrane modules 10 are vertically superposed on each other and connected side-by-side and accommodated in the body 3a.
The first distributing mechanism 13 includes a plurality of vent holes 15 formed along an outer periphery of the vent pipe 12, a distributor 16 formed around the outer peripheries of the vent holes 15 for covering the vent holes 15, a gas conduit 17 communicating with the distributor 16, and a connection hole 18 for connecting the gas conduit 17 and the vent holes to each other. An end of the gas conduit 17 is connected to the gas inlet pipe 4.
The second distributing mechanism 14 has the same structure as that of the first distributing mechanism 13, and includes a plurality of vent holes 19 formed along the outer periphery of the vent pipe 12, a distributor 20 formed around the outer peripheries of the vent holes 19 for covering the vent holes 19, a gas conduit 21 communicating with the distributor 20, and a connection hole 22 connecting the gas conduit 21 and the vent holes 19 with each other. An end of the gas conduit 21 is connected to the gas outlet pipe 5. As shown in
As shown in
As shown in
On the other hand, air is introduced into the humidifier 3 from the compressor (not shown) through the gas inlet pipe 4 and the gas conduit 17 in the humidifier 3. The introduced air flows into the distributor 16 from the gas conduit 17 in the first distributing mechanism 13 of the hollow-fiber membrane module 10. As shown in
According to the humidifier 3 of this embodiment, air which is to be humidified is allowed to flow outside of the hollow-fiber membrane 12, and the off-gas is allowed to flow inside the hollow-fiber membrane 12. Alternatively, the air and gas may flow inside and outside of the hollow-fiber membrane 12 respectively, and the same effect can be obtained.
According to this embodiment, by changing the opening areas of the vent holes in accordance with the distances from the gas conduit, air can flow over the entire outside space of the hollow-fiber membrane, and moisture collected from the off-gas can be dispersed over the air. As a result, the humidifying performance of the hollow-fiber membrane module is enhanced.
According to this embodiment, the compression force and tensile force are applied in the axial direction of the vent pipe. Since the widths of the vent holes in the circumferential direction of the vent pipe are equal to each other and the lengths of the vent holes in the axial direction of the vent pipe are changed and the opening areas of the vent holes are changed, stress applied to the vent pipe between the vent hole and the end of the vent pipe is constant. Buckling or deformation between the vent holes is suppressed, and leakage of gas and deterioration of gas distribution can be reduced. Although the compression force is applied in the axial direction of the vent pipe, since the distances between the adjacent vent holes are set constant and the widths between the vent holes are equal to each other, the hollow-fiber membrane or the vent pipe can be prevented from being damaged. As a result, the lifetime of the hollow-fiber membrane module can be increased. Since the opening areas of the vent holes can be changed only by changing the lengths of the vent holes in the axial direction of the vent pipe, it is easy to design the vent pipe.
In the second embodiment, the humidifier 1 of the first embodiment is improved in order to prevent the fiber of the hollow-fiber membrane from being cut. This humidifier will be explained.
According to the hollow-fiber membrane module 23, the distances from the gas conduit 17 and the vent holes 15d and 15e are long, the flow velocity of air introduced from the gas conduit 17 is reduced and then, air flows outside the hollow-fiber membrane 12 from the vent holes 15d and 15e. Air flowing outside of the hollow-fiber membrane 12 is humidified, and the humidified air is then introduced into the fuel cell 2 through the vent holes 19d and 19e while keeping the low velocity without being affected by the gas conduit 21.
According to this embodiment, vent holes are formed only at positions far from the gas conduit, air with low velocity can be introduced into the hollow-fiber membrane. High velocity air does not come into contact with the hollow-fiber membrane, and the fiber of the hollow-fiber membrane is prevented from being cut and damaged.
In this embodiment also, like the first embodiment, since the opening areas of the vent holes are changed, air is uniformly introduced outside of the hollow-fiber membrane, and the humidifying performance of the humidifier can be enhanced.
The contents of Japanese Patent Application No. 2003-395912, filed Nov. 26, 2003, are hereby incorporated by reference.
Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above will occur to those skilled in the art, in light of the teachings. The scope of the invention is defined with reference to the following claims.
Number | Date | Country | Kind |
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2003-395912 | Nov 2003 | JP | national |