KR101398779B1 - Fuel Cell Humidifier with Improved Cold Resistance - Google Patents

Abstract

The present invention relates to a humidifier for a fuel cell, which is capable of preventing breakage of a hollow fiber membrane despite freezing of condensed water due to a decrease in temperature. The humidifier for a fuel cell according to the present invention comprises: And a second inlet through which the water-containing exhaust gas discharged from the fuel cell flows; The exhaust gas purifier according to any one of claims 1 to 3, further comprising: a housing for accommodating the exhaust gas; an exhaust gas outlet for exhausting the exhaust gas; A desert bundle; And a nonwoven fabric positioned between the housing and the bundle of hollow fiber membranes.

Fuel cell, humidifier, hollow fiber membrane, cold resistance

Description

{Fuel Cell Humidifier with Improved Cold Resistance}

The present invention relates to a humidifier for a fuel cell, and more particularly, to a humidifier for a fuel cell having improved cold resistance that can prevent destruction of a hollow fiber membrane despite freezing of condensed water due to a decrease in temperature.

Fuel cells are power generation cells that produce electricity by combining hydrogen and oxygen. Unlike conventional chemical batteries, such as batteries and accumulators, fuel cells can produce electricity continuously as long as hydrogen and oxygen are supplied, and they are twice as efficient as internal combustion engines because they have no heat loss. In addition, since the chemical energy generated by the combination of hydrogen and oxygen is directly converted into electric energy, the emission of pollutants is low. Therefore, the fuel cell is not only environmentally friendly, but also has the advantage that it can reduce anxiety about resource exhaustion due to an increase in energy consumption.

Such a fuel cell can be classified into a polymer electrolyte membrane fuel cell (PEMFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell SOFC), and an alkaline fuel cell (AFC). Each of these fuel cells operates basically on the same principle, but the type of fuel used, the operating temperature, the catalyst, and the electrolyte are different from each other. Among them, polymer electrolyte fuel cells are known to be most promising not only in small size stationary power generation equipment but also in transportation system because they operate at a lower temperature than other fuel cells and can be miniaturized because of their high output density.

One of the most important factors for improving the performance of a polymer electrolyte fuel cell is to supply a certain amount of water or more to a polymer electrolyte membrane (PEM) of a Membrane Electrode Assembly (MEA) Thereby maintaining the water content. When the polymer electrolyte membrane is dried, the power generation efficiency is rapidly lowered.

The method of humidifying the polymer electrolyte membrane is as follows: 1) a bubbler humidification method in which a pressure vessel is filled with water, a subject gas is passed through a diffuser to supply water, and 2) A direct injection method in which water is directly supplied to the gas flow pipe through calculation using a solenoid valve, and 3) a humidifying membrane method in which water is supplied to a fluidized bed of gas using a polymer separator. Among them, the humidifying membrane type which humidifies the polymer electrolyte membrane by providing water vapor to the gas supplied to the polymer electrolyte membrane using a membrane selectively permeable to only the water vapor contained in the exhaust gas is advantageous in that the humidifier can be made lighter and smaller.

The selective permeable membrane used in the humidifying membrane method is preferably a hollow fiber membrane having a large permeation area per unit volume when a module is formed. That is, when the humidifier is manufactured using the hollow fiber membrane, the hollow fiber membrane having a large contact surface area can be highly integrated, so that the humidification of the fuel cell can be sufficiently performed even at a small capacity, and low cost materials can be used. It is possible to recover the moisture and heat contained in the exhaust gas to be reused through the humidifier. Such a humidifying membrane method using a hollow fiber membrane is mainly applied to automobiles using a fuel cell as a power source.

However, when an automobile using a fuel cell as a power source is shut down, the moisture that has been exchanged through the humidifier is inevitably lost heat and condensed. At this time, condensed water occasionally submerges part of the hollow fiber membrane of the membrane humidifier, and if it is in the winter or cold region, the water will freeze and break the hollow fiber membrane. Once the hollow fiber membrane is destroyed, the flow of the inside and the outside of the hollow fiber membrane is mixed and the performance of the fuel cell stack deteriorates.

As a method for improving the refrigeration characteristics of a humidifier for a fuel cell, there has been proposed a method of removing condensate in the membrane humidifier by performing air blowing after the operation of the fuel cell is completed. However, There is a problem that separate energy must be consumed to remove it. In addition, a method of imparting a gradient difference to the membrane humidifier for freeing the condensed water has been proposed, but this has a problem in that it is difficult to design.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a humidifier for a fuel cell having improved cold resistance without requiring additional energy consumption.

It is another object of the present invention to provide a humidifier for a fuel cell having improved cold resistance that can prevent breakage of a hollow fiber membrane despite freezing of condensed water due to a decrease in temperature.

According to an aspect of the present invention, there is provided a humidifier for a fuel cell comprising: a housing; A hollow fiber membrane bundle including a plurality of hollow fiber membranes each including a tubular support and a hydrophilic polymer membrane coated on the support, the hollow fiber membrane bundle fixed within the housing; And a nonwoven fabric positioned between the housing and the bundle of hollow fiber membranes.

According to another aspect of the present invention, there is provided a humidifier for a fuel cell, comprising: a first inlet through which a reaction gas to be supplied to a fuel cell flows; and a water- A housing having a first inlet and a second inlet; The exhaust gas purifier according to any one of claims 1 to 3, further comprising: a housing for accommodating the exhaust gas; an exhaust gas outlet for exhausting the exhaust gas; A desert bundle; And a nonwoven fabric positioned between the housing and the bundle of hollow fiber membranes.

The hydrophilic polymer membrane is preferably a composite membrane comprising a Nafion membrane or two or more polymers.

The nonwoven fabric is preferably formed of polypropylene, polyethylene terephthalate, or polyethylene, and has a thickness of 1 to 10 mm, more preferably 3 to 5 mm.

According to the humidifier for a fuel cell of the present invention, the cold resistance of the humidifier can be improved without requiring additional energy consumption.

In addition, according to the humidifier for a fuel cell of the present invention, it is possible to prevent breakage of the hollow fiber membrane in spite of freezing of condensed water due to a decrease in temperature, and therefore, even in an automobile running in cold regions, moisture can be supplied to the polymer electrolytic membrane .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a recovery and cleaning apparatus for a hollow fiber membrane module according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic view of a humidifier for a fuel cell according to an embodiment of the present invention.

1, the moisture vapor 100 for a fuel cell according to an embodiment of the present invention includes a housing 110 containing a bundle of the hollow fiber membranes 120. As shown in FIG. A first inlet 111a through which a reaction gas to be supplied to a fuel cell (not shown) flows is formed at one side of the housing 110, and a first inlet 111a through which a reactive gas is supplied to the fuel cell And an outlet 112a is formed.

Both ends of the bundle of hollow fiber membranes 120 are fixed to both sides of the housing 110 with an adhesive 130. The adhesive 130 blocks the flow of air between the first inlet 111a and the first outlet 112a and the central portion of the housing 110, respectively. Since both end portions of the bundle of hollow fiber membranes 120 are open, the hollow portions of the bundle of hollow fiber membranes 120 are communicated with the first inlet 111a and the first outlet 112a, respectively. Accordingly, the reaction gas introduced through the first inlet 111a can be moved to the other side of the housing 110 in which the first outlet 112a is formed through only the hollow portion of the hollow fiber membrane 120 for the humidifier.

A second inlet 111b through which the water-containing exhaust gas discharged from the fuel cell flows into the housing 110 and an exhaust gas flowing into the center of the housing 110 through the second inlet 111b And a second discharge port 112b for discharge.

The operation of the humidifier for a fuel cell according to one embodiment of the present invention will now be described in detail.

The reaction gas to be supplied to the fuel cell flows through the first inlet 111a and the water containing exhaust gas discharged from the fuel cell flows into the interior of the central portion of the housing 110 through the second inlet 111b. The reaction gas introduced through the first inlet port 111a moves toward the first outlet port 112a through the hollow portions of the bundle of the hollow fiber membranes 120. [

Since the exhaust gas flowing into the central portion of the housing 110 through the second inlet 111b contains a large amount of moisture, the reaction gas flowing through the first inlet 111a is in a dry state, ), The difference in humidity occurs inside and outside. The humidity of the inside and outside of the hollow fiber membrane 120 allows the moisture of the exhaust gas to selectively pass through the membrane to the hollow portion of the hollow fiber membrane 120. The humidity of the reaction gas moving along the hollow portion of the hollow fiber membrane 120 toward the first outlet 112a . On the other hand, the exhaust gas from the fuel cell flowing into the central portion of the housing 110 through the second inlet 111b is gradually dried due to the loss of moisture, and the thus dried exhaust gas flows through the second outlet 112b Lt; / RTI > As a result, by operating the humidifier of the present invention as described above, it is possible to supply the reaction gas having a higher humidity than the original reaction gas to the fuel cell.

According to an embodiment of the present invention, the second inlet 111b is formed at a portion adjacent to the first outlet 112a, and the second outlet 112b is formed at a portion adjacent to the first inlet 111a In order to sufficiently permeate the moisture contained in the exhaust gas over the entire portion of the hollow fiber membrane located inside the housing 110. [ That is, in the case of the reactive gas moving from the first inlet 111a to the first outlet 112a, the humidity is low at the first inlet 111a, but water is continuously supplied from the exhaust gas through the hollow fiber membrane 120 And the humidity increases toward the first outlet 112a side. Therefore, the exhaust gas having a relatively low humidity is brought into contact with the portion of the hollow fiber membrane 120 positioned on the first inlet 111a side, and the portion of the hollow fiber membrane 120 positioned on the first outlet 112a side is relatively high Moisture can be uniformly permeated through the entire portion of the hollow fiber membrane 120 by bringing the exhaust gas of humidity into contact.

2 is a cross-sectional view of a hollow fiber membrane for a humidifier according to an embodiment of the present invention.

2, the hollow fiber membrane 120 for a humidifier according to an embodiment of the present invention includes a tubular support 121 having a hollow portion 123, and a hydrophilic (hydrophilic) And a polymer film 122. Since the partial pressure of oxygen contained in the air flowing into the fuel cell stack through the humidifier is maintained, fuel cell performance is not degraded. Therefore, the polymer film 122 should be able to selectively permeate water. A representative example of the material of the hydrophilic polymer film 122 used in the hollow fiber membrane 120 for a humidifier is Nafion ( ^TM ) developed by Dupont Corporation, and has the following chemical structure.

<Chemical structure of Nafion>

In addition, a single membrane such as polysulfone, polyphenyl sulfone, polyetherimide, polyamideimide, polyimide, or a composite membrane in which two or more thereof are mixed can be used as a humidifying membrane for a fuel cell.

Nafion membranes are preferred in the manufacture of membrane humidifiers because they have fast moisture transmission and good gas barrier effects, but they are expensive. Therefore, studies on low-cost, high-performance hollow fiber membranes have been actively conducted. For example, the composite membranes of polythiuramide and polyphenylsulfone or polysulfone and polyphenyl sulfone are not only inexpensive, but also provide about 80% Respectively. When the composite membrane is designed optimally, a membrane humidifier having the same humidification performance as the Nafion membrane on the same volume basis can be produced.

However, unlike a Nafion membrane having a dense microstructure, a single membrane such as polyimide, polyphenyl sulfone, polysulfone, polyamideimide, polyimide, or a composite membrane in which two or more thereof are mixed has a porous structure Therefore, mechanical properties are relatively low. Thus, in the case of a single membrane or a composite membrane of this material, the damage of the membrane caused by freezing of the condensed water inside the humidifier is more severe than that of the membrane. That is, when condensed water is frozen in a state where the film is immersed in condensed water, not only the microstructure of the film is destroyed but also the macroscopic destruction of the film breaks or presses is caused.

In order to solve the above problems, the humidifier 100 for a fuel cell according to an embodiment of the present invention further includes a nonwoven fabric 140 positioned between the housing 110 and the bundle of the hollow fiber membranes 120.

FIG. 3 is a cross-sectional view of the humidifier 100 for the fuel cell of FIG. 1 cut along I and I 'lines.

3, the humidifier 100 for a fuel cell according to an embodiment of the present invention includes a humidifier housing 110 and a nonwoven fabric (not shown) disposed between the bundle of the hollow fiber membranes 120 and surrounding the bundle of the hollow fiber membranes 120 140).

Due to the presence of the nonwoven fabric 140, it is possible to prevent the hollow fiber membrane 120 from being locked to the condensed water generated after the operation of the fuel cell system stops. The condensed water generated is impregnated into the nonwoven fabric 140 and the condensed water impregnated into the nonwoven fabric 140 breaks the structure of the nonwoven fabric 140 when it is frozen but does not affect the hollow fiber membrane 120. On the other hand, the nonwoven fabric 140 can be continuously used even if its structure is broken by the freezing of condensed water impregnated therein.

The nonwoven fabric 140 has both the water repellency of the material itself and the hygroscopicity due to the microstructure. The characteristic of the nonwoven fabric 140 is that the condensed water generated in the membrane humidifier 100 can not be condensed and consequently the cold resistance of the membrane humidifier 100 is increased. On the other hand, the nonwoven fabric 140 should be free from high temperature water elution. That is, the material itself of the nonwoven fabric 140, as well as the additives that can be added in the production of the nonwoven fabric, should not be dissolved in water at high temperatures. Accordingly, it is preferable that the nonwoven fabric 140 is formed of polypropylene, polyethylene terephthalate, or polyethylene.

According to one embodiment of the present invention, the thickness of the nonwoven fabric 140 is 1 to 10 mm, more preferably 3 to 5 mm. If the thickness of the nonwoven fabric 140 is too small, the amount of water that can be contained therein is small and the effect of reducing the cold resistance is insignificant. If the thickness of the nonwoven fabric 140 is too large, the number of the hollow fiber membranes 120 constituting the membrane humidifier 100 This is because the humidifying performance per unit volume of the membrane humidifier 100 is deteriorated.

Hereinafter, the present invention will be described in more detail with reference to concrete examples and comparative examples. These embodiments are only for the understanding of the present invention and do not limit the scope of the present invention.

&Lt; Example 1 >

A 2 liter (L) membrane humidifier was fabricated using a 2000 polysulfone hollow fiber membrane containing a polypropylene spunbond nonwoven fabric. After the operation was stopped during normal operation, the humidifier was left in a cold storage room at -20 ° C. After about 5 hours, the frozen membrane humidifier was thawed and the state of the hollow fiber membrane was visually observed. From the macroscopic point of view, the hollow fiber membrane was not destroyed, and the cold copper of the nonwoven fabric had no effect on the performance of the membrane humidifier.

&Lt; Comparative Example 1 &

A 2 liter (L) membrane humidifier was fabricated using 2000 polysulfone hollow fiber membranes without polypropylene spunbond nonwoven. After the operation was stopped during normal operation, the humidifier was left in a cold storage room at -20 ° C. After about 5 hours, the frozen membrane humidifier was thawed and the state of the hollow fiber membrane was visually observed. The surface of the hollow fiber membranes corresponding to about 10% was depressed due to the cold corrosion phenomenon of the ice, and the humidification performance of the membrane humidifier also deteriorated.

&Lt; Example 2 >

A membrane humidifier of 2 liters (L) in size was fabricated by using 2000 strands of polyetherimide-polysulfone composite hollow fiber membrane containing polypropylene spunbond nonwoven fabric. After the operation was stopped during normal operation, the humidifier was left in a cold storage room at -20 ° C. After about 5 hours, the frozen membrane humidifier was thawed and the state of the hollow fiber membrane was visually observed. From the macroscopic point of view, the hollow fiber membrane was not destroyed, and the cold copper of the nonwoven fabric had no effect on the performance of the membrane humidifier.

&Lt; Comparative Example 2 &

A membrane humidifier of 2 liters (L) in size was fabricated using 2000 polyisidiimide-polysulfone composite hollow fiber membranes without polypropylene spunbond nonwoven fabric. After the operation was stopped during normal operation, the humidifier was left in a cold storage room at -20 ° C. After about 5 hours, the frozen membrane humidifier was thawed and the state of the hollow fiber membrane was visually observed. The number of hollow fiber membranes corresponding to about 5% was cut off at the center of the membrane due to the impact, and the number of hollow fiber membranes corresponding to about 10% had the membrane surface pressed.

&Lt; Example 3 >

A membrane humidifier of 2 liters (L) in size was fabricated using 2000 polyphenylsulfone-polysulfone-polyamideimide composite hollow fiber membranes containing polyethylene terephthalate spunbond nonwoven fabric. After the operation was stopped during normal operation, the humidifier was left in a cold storage room at -20 ° C. After about 5 hours, the frozen membrane humidifier was thawed and the state of the hollow fiber membrane was visually observed. From the macroscopic point of view, the hollow fiber membranes were not destroyed, and the non-woven fabric's cold copper had no effect on the performance of the membrane humidifier.

&Lt; Comparative Example 3 &

A membrane humidifier of 2 liters (L) in size was fabricated using 2000 polyphenylsulfone-polysulfone-polyamideimide composite hollow fiber membranes containing no polyethylene terephthalate spunbond nonwoven fabric. After the operation was stopped during normal operation, the humidifier was left in a cold storage room at -20 ° C. After about 5 hours, the frozen membrane humidifier was thawed and the state of the hollow fiber membrane was visually observed. The membrane surface of the number of hollow fiber membranes corresponding to about 5% was pressed.

<Example 4>

A 2 liter (L) membrane humidifier was fabricated using a 2000-strand Nafion hollow fiber membrane containing a polypropylene spunbond nonwoven fabric. After the operation was stopped during normal operation, the humidifier was left in a cold storage room at -20 ° C. After about 5 hours, the frozen membrane humidifier was thawed and the state of the hollow fiber membrane was visually observed. From the macroscopic point of view, the hollow fiber membrane was not destroyed, and the cold copper of the nonwoven fabric had no effect on the performance of the membrane humidifier.

&Lt; Comparative Example 4 &

A 2 liter (L) membrane humidifier was fabricated using a 2000-strand Nafion hollow fiber membrane containing a polypropylene spunbond nonwoven fabric. After the operation was stopped during normal operation, the humidifier was left in a cold storage room at -20 ° C. After about 5 hours, the frozen membrane humidifier was thawed and the state of the hollow fiber membrane was visually observed. The membrane surface of the number of hollow fiber membranes corresponding to about 3% was pressed.

1 is a schematic view of a humidifier for a fuel cell according to an embodiment of the present invention,

2 is a cross-sectional view of a hollow fiber membrane for a humidifier according to an embodiment of the present invention,

3 is a cross-sectional view of the humidifier for fuel cell of FIG. 1 cut along I and I 'lines.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

100: humidifier for fuel cell 110: housing

111a: first inlet 111b: second inlet

112a: first outlet 112b: second outlet

120: hollow fiber membrane for humidifier 121: tubular support

122: hydrophilic polymer film 123: hollow part

130: Adhesive 140: Nonwoven fabric

Claims (12)

housing; A hollow fiber membrane bundle including a plurality of hollow fiber membranes each including a tubular support and a hydrophilic polymer membrane coated on the support, the hollow fiber membrane bundle fixed within the housing; And And a nonwoven fabric positioned between the housing and the bundle of hollow fiber membranes. The humidifier for a fuel cell according to claim 1, wherein the hydrophilic polymer membrane is a Nafion membrane. The humidifier for a fuel cell according to claim 1, wherein the hydrophilic polymer membrane is a composite membrane comprising two or more polymers. The humidifier for a fuel cell according to claim 3, wherein the composite membrane is a composite membrane comprising at least two of polyimide, polyphenyl sulfone, polysulfone, polyamideimide, and polyimide. The humidifier for a fuel cell according to claim 3, wherein the composite membrane comprises polyetherimide and polyphenyl sulfone. The humidifier for a fuel cell according to claim 3, wherein the composite membrane comprises polysulfone and polyphenyl sulfone. The humidifier for a fuel cell according to claim 1, wherein the nonwoven fabric is formed of polypropylene, polyethylene terephthalate, or polyethylene. The humidifier for a fuel cell according to claim 1, wherein the thickness of the nonwoven fabric is 1 to 10 mm. The humidifier for a fuel cell according to claim 8, wherein the thickness of the nonwoven fabric is 3 to 5 mm. A housing including a first inlet through which a reaction gas to be supplied to the fuel cell flows, and a second inlet through which moisture containing exhaust gas discharged from the fuel cell flows; The exhaust gas purifier according to any one of claims 1 to 3, further comprising: a housing for accommodating the exhaust gas; an exhaust gas outlet for exhausting the exhaust gas; A desert bundle; And And a nonwoven fabric positioned between the housing and the bundle of hollow fiber membranes. 11. The fuel cell system according to claim 10, wherein the housing comprises: a first outlet connected to the hollow fiber membrane for supplying the humidified reaction gas to the fuel cell; and a second outlet for discharging the exhaust gas, And a second outlet for supplying the fuel to the humidifier. 12. A fuel cell system comprising the humidifier for a fuel cell according to any one of claims 1 to 11.

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