KR102152207B1 - Air supplying system for a fuel cell - Google Patents

Abstract

The present invention relates to an air supply apparatus for a fuel cell with easy humidity control, and the air supply apparatus for a fuel cell according to the present invention comprises: a compressor for supplying dry air; A distributor for distributing the dry air through a first path and a second path; A humidifier for supplying humid air by heating and humidifying the dry air in the first path; And a mixing chamber for mixing the dry air of the second path with the humid air supplied from the humidifier and supplying the supplied air to the fuel cell as supply air having a desired humidity.

Description

Air supply system for fuel cell with easy humidity control {AIR SUPPLYING SYSTEM FOR A FUEL CELL}

The present invention relates to an air supply device for a fuel cell with easy humidity control, and more specifically, air for a fuel cell capable of supplying low-humidity and high-humidity air smoothly by mixing dry air and humid air to control humidity. It relates to the supply device.

In general, a fuel cell is an energy conversion device that converts chemical energy of fuel into electrical energy. Unlike other energy conversion devices in the past, fuel cells are not limited by the Carnot cycle, so they have very high energy efficiency and almost no pollution emissions. There is no such thing as a mobile phone or laptop power supply, a car power source, and a large-scale combined heat generation system.

In a fuel cell, the fuel gas supplied to the anode and the gas supplied to the cathode undergo oxidation and reduction reactions on the electrode surface, respectively, and electrons generated in the anode by this reaction move along the external circuit, Hydrogen ions move to the cathode through the electrolyte. As such, fuel cells require an electrolyte to transfer ions, and depending on the type of electrolyte used, a polymer electrolyte fuel cell (PEMFC, Proton Exchange Membrane Fuel Cell), a direct methanol fuel cell (DMFC, Carbonate Fuel Cell), and a phosphoric acid type It is divided into fuel cells (PAFC, Phosphoric Acid Fuel Cell), alkaline fuel cells (AFC, Alkaline Fuel Cell), and solid oxide fuel cells (SOFC, Solid Oxide Fuel Cell).

Among them, a polymer electrolyte fuel cell is a fuel cell that uses a polymer membrane that is electrically insulator and has hydrogen ion exchange characteristics as an electrolyte. It has a low operating temperature, short start-up time, high power density, high efficiency, and a small volume due to simple peripheral devices. Because it can be manufactured with and almost no pollutant emissions, it is in the spotlight as an alternative power source.

A polymer electrolyte fuel cell (PEMFC) is composed of a polymer membrane, electrodes (anode, cathode), and a separator to form a stack. Porous anodes and cathodes are attached to both sides of the polymer membrane, and electrochemical oxidation of hydrogen occurs at the anode, and electrochemical reduction of oxygen, an oxidizing agent, occurs at the cathode.

The polymer electrolyte fuel cell operates at a lower temperature than other fuel cells, has a short start-up time and a high current density. Since it does not use a liquid electrolyte, there is little corrosion problem, easy operation, simple design and easy manufacturing. However, since platinum (Pt) is used as an electrode catalyst, the manufacturing cost is high, there is a risk of the catalyst being poisoned by carbon monoxide (CO), the cost of the polymer membrane used as an electrolyte is also high, and it is difficult to control the moisture content of the polymer membrane during operation. There is this. Therefore, in order to control the moisture of the polymer membrane, maximize the efficiency of the expensive Pt electrode catalyst, and improve the reaction rate, the temperature and internal pressure of the battery must be uniformly controlled.

The performance of a polymer electrolyte fuel cell (PEMFC) changes due to temperature and pressure humidification characteristics, and the reaction rate, mass transfer, ionic conductivity of the electrolyte, and cell resistance change depending on the temperature. The partial pressure of, gas solubility, and mass transfer change.

In particular, the polymer electrolyte fuel cell (PEMFC) is mainly made of a proton conductive polymer electrolyte membrane, which is a perfluorinated sulfonic acid polymer, and humidification is very important in the polymer electrolyte membrane.

Basically, the ionic conductivity of the polymer electrolyte membrane increases as the moisture content increases.In particular, the cation conductivity of the polymer membrane changes according to the moisture content of hydrogen and oxygen (air), which are reactive groups, and plays an important role in determining the performance of the fuel cell.

This polymer electrolyte membrane selectively permeates only hydrogen ions (moved with 2 to 3 water molecules), and when the polymer electrolyte membrane is dried, performance degradation is caused due to a decrease in water content, and no reaction occurs when completely dried. On the other hand, when a large amount of moisture is absorbed, the weight increases by about 50% or more, and when moisture is excessive, condensation of water occurs. The condensed water blocks the porous electrode and blocks the supply of fuel.

Therefore, in order to improve the performance of the polymer electrolyte fuel cell, not only the reaction mechanism in the electrochemical reaction must be investigated, but also the temperature and humidification conditions for optimal cell operation must be studied. Temperature and humidity must be freely controlled as desired. In particular, it is essential to control the humidity of the supplied air.

In the conventional case, a humidifier was simply used to control the humidity of air supplied to the fuel cell. These humidifiers are bubble-type humidifiers, and when hydrogen and air are supplied into the water under the distilled water into the distilled water tank, the supplied hydrogen and air rise up above the distilled water in the form of bubbles and come out while being humidified. It has a structure in which the humidity of the air is determined accordingly.

However, this humidity control method has a problem in that it is difficult to control the relative humidity because the control speed is slow because the amount of moisture vaporized by controlling the temperature inside the humidifier with an external heat source.

Korean Patent Publication No. 10-0624196 (2006.09.07.)

Accordingly, an object of the present invention is to provide an air supply device for a fuel cell with easy humidity control, which can overcome the above-described conventional problems.

Another object of the present invention is to provide an air supply device for a fuel cell that can easily and quickly adjust the humidity of air supplied to a fuel cell and can freely and variously control the humidity from a low humidity of less than 10% to a high humidity close to 100%.

According to an embodiment of the present invention for achieving some of the above technical problems, an air supply device for a fuel cell according to the present invention includes: a compressor for supplying dry air; A distributor for distributing the dry air through a first path and a second path; A humidifier for supplying humid air by heating and humidifying the dry air in the first path; And a mixing chamber for mixing the dry air of the second path with the humid air supplied from the humidifier and supplying the supplied air to the fuel cell as supply air having a desired humidity.

The humidifier may include a heater for heating water contained therein, and a temperature sensor for measuring a temperature of water contained therein.

The mixing chamber includes a heater for heating the air introduced into the interior. A temperature sensor for measuring the temperature of the air introduced into the interior, a humidity sensor for measuring the humidity of the air introduced into the interior, and a pressure sensor for measuring the pressure of the air introduced into the interior may be provided.

The air supply device includes: a first control valve installed in a supply pipe connecting between the distributor and the humidifier; A second control valve installed in a supply pipe connecting the distributor and the mixing chamber; A third control valve installed in a supply pipe connecting the humidifier and the mixing chamber, and corresponding to the humidity of the air in the mixing chamber measured by the humidity sensor, the first control valve and the second By adjusting the control valve and the third control valve to control the amounts of humid air and dry air introduced into the mixing chamber, air having a desired humidity may be supplied to the fuel cell.

The air supply device may adjust the temperature and pressure in the mixing chamber so that moisture contained in the air is not condensed while the air in the mixing chamber is maintained at a desired humidity.

According to the present invention, the humidity of the air supplied to the fuel cell can be easily and quickly adjusted by mixing the humid air of the first path and the dry air of the second path, and it is possible to adjust the humidity easily and quickly, and to 100% at a low humidity of 10% or less. It has the effect of being able to freely and variously control humidity up to near high humidity.

1 is a schematic diagram of a unit cell of a general polymer electrolyte fuel cell,
2 is a block diagram of an air supply device for a fuel cell according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, without any intention other than to provide a thorough understanding of the present invention to those of ordinary skill in the art to which the present invention pertains.

1 is a schematic diagram of a unit cell of a general polymer electrolyte fuel cell, and FIG. 2 is a block diagram of an air supply device for a fuel cell according to an embodiment of the present invention.

As shown in FIG. 1, when the polymer electrolyte fuel cell supplies hydrogen to one electrode of the fuel cell and air is continuously supplied to the other electrode, the hydrogen gas at one electrode (anode) undergoes an oxidation reaction to generate electrons. Losing. In the other electrode (cathode), oxygen gas contained in the air undergoes a reduction reaction. Electrons generated at the anode side move through an external circuit connected to an electrode (cathode) on the opposite side to generate a current. In addition, in the cathode, oxygen is reduced by obtaining hydrogen that has moved through the electrolyte and electrons that have moved through the circuit. Here, hydrogen and oxygen meet and react to produce water (H ₂ 0) as a by-product.

As shown in FIG. 2, the air supply device 100 for a fuel cell of the present invention is a device for supplying air to the cathode side of the fuel cell described above, and includes a compressor 110, a distributor 120, and a humidifier. (130) and a mixing chamber (140). Additionally, a dryer 112, an air filter 114, and various sensors and heaters may be provided.

The compressor 110 supplies compressed dry air to the distributor 120. The compressed dry air supplied from the compressor 100 is supplied to the distributor 120 by removing moisture from the dryer 112 and removing foreign substances through the air filter 114.

The distributor 120 distributes the dry air supplied from the compressor 110 to a first path and a second path. The distributor 120 may be configured with a mass flow rate controller (MFC) that controls the flow rates of dry air supplied to the first path and the second path.

The humidifier 130 is for supplying wet air to the mixing chamber 140 by heating and humidifying the dry air of the first path. The humidifier 130 warms and humidifies the dry air of the first path, controls the relative humidity through the first humidity sensor HS1, and supplies it to the mixing chamber 140. In the humidifier 130, pure water, that is, distilled water, is stored in the lower portion thereof, and the stored distilled water is vaporized into fine water vapor according to the heated temperature and internal pressure, and then wet air is included in the dry air. do. A mesh net (not shown) for filtering out water droplets contained in the evaporated moisture may be installed on the inside of the humidifier 130, and a temperature sensor TC1 for detecting the internal temperature is installed. In addition, a heater (not shown) for heating water in the humidifier 130 is installed, and the heater is driven according to the temperature sensed by the temperature sensor TC1. Other structures are the same as those of a humidifier well known to those skilled in the art.

The mixing chamber 140 mixes dry air of the second path and wet air supplied from the humidifier 130, and supplies it to the fuel cell as supply air having a desired humidity. do. The mixing chamber 140 includes a heater (not shown) for heating the air introduced into the interior. A temperature sensor (TC3) for measuring the temperature of the air introduced into the interior, a second humidity sensor (HS2) for measuring the humidity of the air introduced into the interior, and a pressure sensor (PS) for measuring the pressure of the air introduced into the interior. ). In the mixing chamber 140, dry air of the second path and wet air supplied from the humidifier 130 are mixed with air to have the temperature and humidity required by the fuel cell. Air of the desired humidity and temperature is supplied to the fuel cell. In particular, by mixing the dry air of the first path, it is possible to supply air with a desired humidity from low humidity (about 10%) to high humidity (about 100%) to the fuel cell.

In addition, in the mixing chamber 140, the temperature and pressure in the mixing chamber 140 are controlled so that moisture contained in the air is not condensed while the air in the mixing chamber 140 is maintained at a desired humidity. This may be performed by a separate controller (not shown) provided in the air supply device 100 and controlling the overall operation.

In addition, the first control valve (V1) installed in the supply pipe connecting the distributor 120 and the humidifier 130, and the supply pipe connecting the distributor 120 and the mixing chamber 140 A second control valve (V2) to be installed, and a third control valve (V3) installed in a supply pipe connecting between the humidifier 130 and the mixing chamber 140 may be provided, and the humidity sensor (HS1) In response to the humidity of the air in the mixing chamber 140 or the humidifier 130 measured through HS2), the first control valve V1, the second control valve V2, and the third control valve By adjusting (V3) to adjust the inflow amounts of the humid air and dry air flowing into the mixing chamber 140, air having a desired humidity can be supplied to the fuel cell. Here, the first control valve (V1) is operated to adjust the inflow amount of air introduced into the humidifier 130 in response to the first humidity sensor (HS1), and the second control valve (V2) and the The 3 control valve V3 may be controlled to adjust the inflow amount of moist air and dry air introduced into the mixing chamber 140 in response to the second humidity sensor HS2.

A supply pipe connecting between the distributor 120 and the mixing chamber 140, a supply pipe connecting the humidifier 130 and the mixing chamber 140, and a connection between the mixing chamber 140 and the fuel cell A line heater (not shown) is installed in each of the supply pipes. The line heater is a means for maintaining a constant temperature of the air supply pipe, thereby maintaining a constant temperature of the supply pipe so that the humidity and temperature of the air supplied to the fuel cell are kept constant.

The operation of the air supply device 100 having the above-described configuration is as follows.

Dry air compressed through the compressor 110 is supplied to the distributor 120 by removing foreign substances and humidity through the dryer 112 and the air filter 114. The distributor 120 distributes dry air through the first path and the second path and supplies dry air through the first path and the second path while controlling the flow rate.

The dry air supplied through the first path is supplied to the humidifier 130, and in the humidifier, the temperature is increased by a heater operating according to the set temperature, and the relative humidity increases by near 100% in the process of passing through the heated water. . The humidified air heated and humidified while passing through the humidifier 130 passes through a line and moves to the mixing chamber 140.

Meanwhile, the dry air supplied through the second path moves directly to the mixing chamber 140.

In the mixing chamber 140, dry air of the second path and wet air supplied from the humidifier 130 are mixed and supplied to the fuel cell as supply air having a desired humidity. do. In the mixing chamber 140, when the humidity of the air is to be increased, the inflow amount of moist air through the first path is increased, and when the humidity of the air is to be lowered, the inflow amount of dry air through the second path is increased. The humidity of the air supplied to the fuel cell can be freely controlled.

As described above, according to the present invention, the humidity of the air supplied to the fuel cell can be easily and quickly controlled by mixing the humid air of the first path and the dry air of the second path, thereby enabling quick and easy humidity control and low humidity of 10% or less. It has the effect of being able to freely and variously control humidity from humidity to high humidity close to 100%.

Since the description of the above-described embodiment is merely an example with reference to the drawings for a more thorough understanding of the present invention, it should not be construed as limiting the present invention. In addition, it will be apparent to those of ordinary skill in the art to which the present invention pertains that various changes and changes can be made without departing from the basic principles of the present invention.

110: compressor 120: distributor
130: humidifier 140: mixing chamber

Claims (5)

In the fuel cell air supply system:
A compressor for supplying dry air;
A distributor for distributing the dry air through a first path and a second path;
A humidifier for supplying humid air by heating and humidifying the dry air in the first path;
A mixing chamber for mixing the dry air of the second path with the humid air supplied from the humidifier, and supplying the supplied air to the fuel cell as supply air having a desired humidity;
A first control valve installed in a supply pipe connecting the distributor and the humidifier;
A second control valve installed in a supply pipe connecting the distributor and the mixing chamber;
And a third control valve installed in a supply pipe connecting between the humidifier and the mixing chamber,
In response to the humidity of the air in the mixing chamber measured by a humidity sensor, the amount of humid air and dry air introduced into the mixing chamber by controlling the first control valve, the second control valve and the third control valve By adjusting the, air of a desired humidity is supplied to the fuel cell,
The humidifier includes a heater for heating water contained therein and a temperature sensor for measuring the temperature of water contained therein,
The mixing chamber includes a heater for heating the air introduced into the interior. A temperature sensor for measuring the temperature of air introduced into the interior, a humidity sensor for measuring the humidity of the air introduced into the interior, and a pressure sensor for measuring the pressure of the air introduced into the interior,
For a fuel cell, characterized in that a line heater is installed in each of a supply pipe connecting the distributor and the mixing chamber, a supply pipe connecting the humidifier and the mixing chamber, and a supply pipe connecting the mixing chamber and the fuel cell. Air supply. delete delete delete The method according to claim 1,
And the air supply device adjusts the temperature and pressure in the mixing chamber so that moisture contained in the air is not condensed while the air in the mixing chamber is maintained at a desired humidity.

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