TWI618292B - Gas management method for anode gas recirculation fuel cell and system thereof - Google Patents

Abstract

A gas management method for an anode circulating fuel cell is applied to an anode circulating fuel cell, wherein the anode circulating fuel cell comprises a fuel cell unit, the fuel cell unit comprises an anode, the anode comprises a conductive plate, and the conductive plate comprises the first block and The second block, wherein the first block corresponds to a gas inlet and the second block corresponds to a gas outlet. The gas management method for an anode circulating fuel cell includes performing a closed discharge step, performing a first monitoring step, performing a cyclic discharge step, performing a gas compression step, and performing a second monitoring step. Thereby, it is beneficial to determine the opening timing of the exhaust valve, and can reduce the opening frequency of the exhaust valve, thereby facilitating the improvement of energy efficiency.

Description

Gas management method and system for anode circulating fuel cell

The present invention relates to a gas management method and system for a fuel cell, and more particularly to a gas management method and system for an anode circulating fuel cell.

Human dependence on energy is deepening with industrialization. However, in the process of using energy, the products accompanying it often cause environmental burden. For example, in the process of burning fossil fuels such as petroleum and coal, a large amount of carbon dioxide is emitted to cause a greenhouse effect; or, a disposable dry battery can no longer be used after the power is used, and the waste is treated. In addition, disposable dry batteries contain heavy metals such as mercury and cadmium, which may cause water and soil pollution. Therefore, how to develop green energy has become one of the goals of the relevant industry and academic circles.

Among many green energy sources, fuel cells can provide continuous and uninterrupted power supply by continuously supplying fuel and oxidants such as oxygen or air. It is not like disposable dry battery power, it needs to be discarded, and it is not like charging electricity. The pool needs to be charged when the power is exhausted and cannot be continuously powered. In addition, the main products of the fuel cell when discharging are water and heat, and depending on the type of fuel, there may be a small amount of carbon dioxide, which can effectively avoid the generation of pollutants compared with other energy sources, and is highly valued.

Common fuel cells include Proton Exchange Membrane Fuel Cell (PEMFC), Alkaline Fuel Cell (AFC), Phosphoric Acid Fuel Cell (PAFC), and molten carbonate fuel cell ( Molten Carbonate Fuel Cell (MCFC), Solid Oxide Fuel Cell (SOFC), and the like. The classification of fuel cells mainly depends on the electrolyte materials. In addition, the fuels used in different fuel cells may be slightly different from the oxidants, but the operation principle is that the fuel is oxidized at the anode inlet end and at the cathode inlet end. An oxidizing agent is introduced to cause a reduction reaction of the oxidizing agent. The remaining fuel and residual oxidant that are not involved in the reaction flow out from the anode outlet end and the cathode outlet end, respectively. In order to improve the fuel utilization rate of the fuel cell, an anode circulation type may be employed, that is, a gas pushing device such as a gas pump or an injector is installed, and the remaining fuel that is not involved in the reaction at the anode outlet end is sent back to the anode inlet end to be mixed with fresh fuel. After that, it is sent to the anode.

However, during the discharge of the fuel cell, impurities of the cathode, such as nitrogen or water generated by the reaction, may still diffuse to the anode through the electrolyte to lower the concentration of the fuel, thereby causing a decrease in battery performance. Therefore, an exhaust valve is often installed at the anode outlet end to timely remove impurities accumulated in the anode, so that the performance of the fuel cell is increased.

The timing of the exhaust valve opening shuts off the performance, life and energy efficiency of the fuel cell. For example, too frequent opening can result in wasted fuel, while delaying too long opening can result in poor fuel cell performance and compromised life. Nowadays, methods for judging the timing of opening the exhaust valve have been developed, including voltage change rate and current integration; however, the methods and systems are too complicated to be applied to fuel cells commonly used today. Therefore, relevant industry and scholars still seek a gas management method and system for an anode circulating fuel cell that is simple and can effectively judge the timing of opening the exhaust valve.

An object of the present invention is to provide a gas management method for an anode circulation type fuel cell, which is advantageous for determining an opening timing of an exhaust valve, thereby avoiding waste of fuel, deteriorating battery life, and reducing an opening frequency of an exhaust valve, and further Conducive to improving energy efficiency.

Another object of the present invention is to provide a gas management system for an anode circulating fuel cell which has the advantages of simple structure and is advantageous for use in a fuel cell which is commonly used today.

According to an embodiment of an aspect of the present invention, a gas management method for an anode circulating fuel cell is provided for use in an anode circulating fuel cell. The anode circulating fuel cell comprises a fuel cell unit, the fuel cell unit comprises an anode, the anode comprises a conductive plate, and the conductive plate comprises a first block and a second block. The first block corresponds to a gas inlet, and the second block corresponds to a gas outlet. A gas management method for an anode circulating fuel cell includes performing a closed discharge step, performing a first monitoring step, and performing a cycle The discharging step, performing a gas compression step, and performing a second monitoring step. The closed discharge step is to discharge the fuel cell unit when the gas push device, the exhaust valve, and the recovery valve are closed. The first monitoring step is to monitor a variation characteristic value, and when the variation characteristic value is less than or equal to a preset critical characteristic value, turning on the gas pushing device and the recovery valve, wherein the variation characteristic value is the second block current density and the fuel cell The ratio of the overall current density of the unit. The cyclic discharge step is to discharge the fuel cell unit when the gas push device and the recovery valve are opened and the exhaust valve is closed. The gas compression step is to close the recovery valve to compress the gas in the gas push device and the recovery valve. The second monitoring step is to monitor the variation characteristic value. When the variation characteristic value is less than or equal to the critical characteristic value, the exhaust valve is opened to connect the anode to the outside.

According to the gas management method of the anode circulation type fuel cell described above, the method for setting the critical characteristic value may include performing a predetermined closed discharge step and performing a voltage monitoring step. The preset closed discharge step is to discharge the fuel cell unit at a preload current density and a preload voltage when the gas push device, the exhaust valve and the recovery valve are closed. The voltage monitoring step is to monitor the preload voltage. When the preload voltage drops by a voltage threshold, the current density of the second block is measured as the critical current density, and the ratio of the critical current density to the preload current density is taken as the critical feature. value. The voltage threshold can be 0.1 volts.

According to the gas management method of the anode circulation type fuel cell described above, the gas pushing device may be a gas pump, and the fuel cell unit may be a proton exchange membrane fuel cell.

According to an embodiment of the present invention, a gas management system for an anode circulating fuel cell includes an anode circulating fuel cell, a first current sensor, a second current sensor, and a control module. The anode circulating fuel cell includes a fuel cell unit, a gas circulation unit, and an exhaust valve. The fuel cell unit includes an anode, a gas inlet, and a gas outlet, wherein the anode includes a conductive plate, the conductive plate includes a first block and a second block, the first block corresponds to a gas inlet, and the second block corresponds to a gas outlet. The gas circulation unit connects the gas inlet and the gas outlet. The gas circulation unit comprises a gas pushing device and a recovery valve. The gas pushing device is disposed between the gas outlet and the gas inlet to provide power for the gas in the anode to flow from the gas outlet to the gas inlet, and the recovery valve is disposed on the gas pushing device and Between the gas inlets. The exhaust valve is disposed between the gas push device and the recovery valve. The first current sensor is used to measure the overall current of the fuel cell unit. The second current sensor is configured to measure the second block current. The control module is connected to the first current sensor, the second current sensor, the gas pushing device, the exhaust valve and the recovery valve. The control module stores a critical feature value. The control module receives the second block current and the overall current of the fuel cell unit and calculates a ratio of the second block current density to the overall current density of the fuel cell unit as a variation characteristic value. The control module compares the variation characteristic value and the critical characteristic value to control the closed gas pushing device, the exhaust valve and the recovery valve.

According to the gas management system of the anode circulation type fuel cell, the control module can compare the variation characteristic value and the critical characteristic value when the gas pushing device, the exhaust valve and the recovery valve are closed, and when the variation characteristic value is less than or equal to the critical characteristic. When the value is turned on, the gas pushing device and the recovery valve are turned on to make the anode Extremely in a gas circulation state.

According to the gas management system of the anode circulation type fuel cell, the control module can compare the variation characteristic value and the critical characteristic value when the gas pushing device is opened, the exhaust valve and the recovery valve are closed, and when the variation characteristic value is less than or equal to the pre- When the critical characteristic value is set, the exhaust valve is opened to connect the anode to the outside.

According to the foregoing gas management system for an anode circulating fuel cell, wherein the gas pushing device may be a gas pump, and the fuel cell unit may be a proton exchange membrane fuel cell.

100‧‧‧Gas management system for anode circulating fuel cells

110, 810‧‧‧ fuel cell unit

111, 811‧‧‧ anode

112‧‧‧ membrane electrode group

113‧‧‧ cathode

114, 814‧‧‧ Conductive plate

114a, 814a‧‧‧ first block

114b, 814b‧‧‧ second block

115‧‧‧ Conductive plate

116, 816‧‧‧ gas inlet

117, 817‧‧‧ gas exports

120‧‧‧ gas circulation unit

121‧‧‧ gas push device

122‧‧‧Recycling valve

123‧‧‧ gas pipeline

130, 830‧‧ ‧ exhaust valve

140, 840‧‧‧ first current sensor

150, 850‧‧‧second current sensor

160, 860‧‧‧ control module

200‧‧‧load

300‧‧‧Gas management method for anode circulating fuel cell

310, 320, 330, 340, 350 ‧ ‧ steps

500‧‧‧How to set critical eigenvalues

510, 520‧ ‧ steps

600‧‧‧conductive plate

610‧‧‧ wire

620‧‧‧Silver glue

800‧‧‧Gas management system for anode-enclosed fuel cells

L1‧‧‧ Length of the first block

L2‧‧‧ Length of the second block

Current density of the first block of J1‧‧

J‧‧‧The overall current density of the fuel cell unit

Cv‧‧‧Change eigenvalue

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; 2 is a schematic diagram showing a gas management system of an anode circulating fuel cell of FIG. 1 connected to a load; and FIG. 3 is an anode circulating fuel cell according to another embodiment of the present invention. Flow chart of the steps of the gas management method; FIG. 4A is a flow diagram of the anode gas in the closed discharge step in FIG. 2; FIG. 4B is a flow diagram of the anode gas in the cyclic discharge step in FIG. 4C is a flow diagram of the anode gas in the gas compression step in FIG. 2; FIG. 4D is a schematic diagram of the flow of the anode gas when the exhaust valve is opened in FIG. 2; FIG. 5 is a diagram showing another embodiment of the present invention. FIG. 6 is a schematic view showing a conductive plate used in the anode of Embodiment 1; FIG. 7A is a relationship between voltage and time in Embodiment 1; and FIG. 7B is a first embodiment; Normalized current density, position versus time; FIG. 8 is a schematic diagram showing a gas management system of an anode-closed fuel cell according to Comparative Example 1 of the present invention; FIG. 9A is a comparison of Comparative Example 1 at different current densities Figure 9B is a plot of current density, position versus time for different current densities; Figure 10A is a plot of voltage vs. time for Comparative Example 1; and 10B The graph shows the relationship between normalized current density, position and time in Comparative Example 1.

<Gas Management System for Anode Circulating Fuel Cell>

1 is a schematic view of a gas management system 100 for an anode circulating fuel cell in accordance with an embodiment of the present invention. In the first picture, Yang The gas management system 100 for a pole cycle fuel cell includes an anode circulating fuel cell (not labeled), a first current sensor 140, a second current sensor 150, and a control module 160.

The anode circulating fuel cell includes a fuel cell unit 110, a gas circulation unit 120, and an exhaust valve 130.

The fuel cell unit 110 includes an anode 111, a gas inlet 116, and a gas outlet 117. The anode 111 includes a conductive plate 114. The conductive plate 114 includes a first block 114a and a second block 114b. The first block 114a corresponds to the gas inlet 116. The second block 114b corresponds to the gas outlet 117.

Specifically, the fuel cell unit 110 may be a single fuel cell or a fuel cell stack composed of a plurality of fuel cells. Further, the battery unit 110 may be, but not limited to, a proton exchange membrane fuel cell, an alkaline fuel cell, and a phosphoric acid fuel cell. A molten carbonate fuel cell or a solid oxide fuel cell may use different fuels depending on different fuel cells. For example, a proton exchange membrane fuel cell and an alkaline fuel cell may use hydrogen as a fuel. In the first embodiment, the fuel cell unit 110 is a single fuel cell, and the fuel cell unit 110 is a proton exchange membrane fuel cell. The fuel cell unit 110 includes an anode 111, a membrane electrode assembly 112, and a cathode 113. The cathode 113 includes a conductive plate 115. However, it is merely illustrative, and the invention is not limited thereto. Furthermore, since the present invention is directed to a management method and system for anode gas of an anode circulating fuel cell, other details regarding the fuel cell unit 110, such as a fuel source, a cathode inlet, a cathode outlet, an oxidant source, etc., are omitted. . In other embodiments, when the fuel cell unit 110 is a fuel cell stack, the anode 111 refers to the anode of the fuel cell located at the outermost side of the fuel cell stack. this In addition, the first block 114a and the second block 114b can be obtained by changing a conventional anode conductive plate into two discontinuous conductive plates. The gas inlet 116 is used to supply a fuel (not shown) to the anode 111. The gas outlet 117 is used for the gas in the anode 111 (hereinafter also referred to as anode gas) to flow out, and the gas in the anode 111 contains the unreacted reaction. The remaining fuel and impurities diffused by the cathode 113 such as nitrogen or water. The conductive plate 114 is used to collect the current generated by the anode 111. In the first block 114a and the second block 114b, the first block 114a is closer to the gas inlet 116, and the second block 114b is closer to the gas outlet 117, in other words, The first block 114a can be used to collect current from the region of the anode 111 proximate to the gas inlet 116, and the second block 114b can be used to collect current from the region of the anode 111 proximate to the gas outlet 117. The length L1 of the first block 114a may be greater than or equal to the length L2 of the second block 114b, thereby facilitating monitoring of the current density of the anode 111 close to the region of the gas outlet 117, and adjusting the first block 114a according to actual needs. The ratio of the length L1 to the length L2 of the second block 114b is not limited thereto. Preferably, the length L1 of the first block 114a may be 9 to 1 to 19 to 1 than the length L2 of the second block 114b. In addition, the distance between the first block 114a and the second block 114b in FIG. 1 is only an example to indicate that the conductive plate 114 is divided into two blocks, and the invention is not limited thereto.

The gas circulation unit 120 connects the gas inlet 116 and the gas outlet 117. The gas circulation unit 120 includes a gas pushing device 121, a recovery valve 122, and a gas line 123. The gas pushing device 121 is disposed on the gas line 123 and disposed between the gas outlet 117 and the gas inlet 116 for providing gas in the anode 111 from the gas outlet 117 to the gas inlet 116. The power of mobility. The recovery valve 122 is disposed on the gas line 123 and disposed between the gas pushing device 121 and the gas inlet 116. Specifically, when both the gas pushing device 121 and the recovery valve 122 are opened, the gas discharged from the gas outlet 117 of the anode 111 can be returned to the gas inlet 116, mixed with fresh fuel, and then introduced into the anode 111. Thereby, the remaining fuel that is not involved in the reaction can be recovered, and the fuel utilization rate can be improved. The gas push device 121 can be a gas pump. The recovery valve 122 can be a solenoid valve.

The exhaust valve 130 is connected to the gas line 123 and disposed between the gas pushing device 121 and the recovery valve 122. The exhaust valve 130 is used to connect the anode 111 to the outside (not otherwise labeled). During the discharge of the fuel cell unit 110, since the anode 111 gradually accumulates impurities, the voltage drop that the fuel cell unit 110 can provide (i.e., the performance of the fuel cell unit 110 decreases), at this time, the exhaust valve can be opened. 130 causes the anode 111 to communicate with the outside, allowing the impurities in the anode 111 to be discharged to the outside to achieve a purifying function, thereby restoring the performance of the fuel cell unit 110, in other words, the exhaust valve 130 is normally in a closed state, which is opened when the impurities are discharged. . The exhaust valve 130 can be a solenoid valve.

The first current sensor 140 is used to measure the overall current of the fuel cell unit 110, and the second current sensor 150 is used to measure the current of the second block 114b. The first current sensor 140 and the second current sensor 150 can be, but not limited to, an ammeter or a three-meter, and the ammeter can be used to measure the current. The current can be converted into a current density by a formula, with respect to current and current. The conversion of density is conventional and will not be repeated here. Specifically, the second current sensor 150 is connected in series with the second block 114b, and the first block 114a and the second block 114b After being connected in parallel, the first current sensor 140 is connected in series; therefore, the second current sensor 150 can measure the current of the second block 114b, and the first current sensor 140 can measure the overall current of the fuel cell unit 110. .

The control module 160 connects the first current sensor 140, the second current sensor 150, the gas pushing device 121, the exhaust valve 130, and the recovery valve 122. The control module 160 stores a critical feature value. The control module 160 receives the current of the second block 114b and the overall current of the fuel cell unit 110, calculates the current density of the second block 114b and the overall current density of the fuel cell unit 110, and calculates the current of the second block 114b. The ratio of the density to the overall current density of the fuel cell unit 110 is used as a variation characteristic value. When the overall current density of the fuel cell unit 110 is J, the current density of the second block 114b is J2, and the variation characteristic value is Cv, which satisfies the following conditions. :Cv=J2/J. The control module 160 compares the variable characteristic value with the critical characteristic value to control the closed gas pushing device 121, the exhaust valve 130, and the recovery valve 122. Specifically, the connection relationship between the control module 160 and the first current sensor 140, the second current sensor 150, the gas pushing device 121, the exhaust valve 130, and the recovery valve 122 is a signal connection, and the signal connection can be wired. Connection or wireless connection, in Figure 1 is a dotted line to express the relationship of signal connections. The control module 160 can be implemented by installing a Data Acquisition card and a corresponding software on a computer. For example, the data capture card can be, but is not limited to, NI manufactured by National Instruments Corporation. 9219, NI 9401 or NI 9205, etc., can be used with the corresponding software of National Instruments.

Figure 2 is a diagram showing the gas of the anode circulating fuel cell of Figure 1. A schematic diagram of the body management system 100 coupled to a load 200. As shown in FIG. 2, when a load 200 is powered by the gas management system 100 of the anode circulating fuel cell, the load 200 is respectively connected to the conductive plate 114 of the anode 111 and the conductive plate 115 of the cathode 113, as shown in FIG. The first current sensor 140 measures the overall current of the fuel cell unit 110.

<Gas Management Method of Anode Circulating Fuel Cell>

3 is a flow chart showing the steps of a gas management method 300 for an anode circulating fuel cell according to another embodiment of the present invention. The gas management method 300 of the anode circulating fuel cell can be applied to the anode gas of the anode circulating fuel cell. Hereinafter, the gas management method 300 for the anode circulation type fuel cell will be specifically described in conjunction with the gas management system 100 of the anode circulating fuel cell of FIG. 2 and the load 200. In FIG. 3, the gas management method 300 for an anode circulating fuel cell includes a step 310, a step 320, a step 330, a step 340, and a step 350.

Step 310 is to perform a closed discharge step of discharging the fuel cell unit 110 when the gas push device 121, the exhaust valve 130, and the recovery valve 122 are closed. Please refer to FIG. 4A for cooperation. It is a schematic diagram of the flow of anode gas (not shown) in the closed discharge step in FIG. 2. Since FIG. 4A is used to explain the flow of anode gas, only the anode is shown. The anode circulation type fuel cell in the gas management system 100 of the circulating fuel cell, and the remaining components are omitted; in addition, "X" in Fig. 4A indicates a closed state, and "arrow" indicates a flow direction of the anode gas, the following 4B, 4C, and 4D are the same and will not be described again. As can be seen from FIG. 4A, when step 310 is performed, the gas pushing device 121 and the exhaust valve 130 are Both the recovery valve 122 and the recovery valve 122 are closed. Therefore, the remaining fuel in the anode 111 that is not involved in the reaction cannot be transferred back to the gas inlet 116. The "closed" in the closed discharge step means that the anode 111 is not in a gas circulation state.

Step 320 is to perform a first monitoring step of monitoring the variation characteristic value. When the variation characteristic value is less than or equal to the preset critical characteristic value, the gas pushing device 121 and the recovery valve 122 are turned on, so that the anode 111 is in a gas circulation state. Please refer to the previous section for details on the variation eigenvalues.

Step 330 is to perform a cyclic discharge step of discharging the fuel cell unit 110 when the gas pushing device 121 and the recovery valve 122 are opened and the exhaust valve 130 is closed. Referring to FIG. 4B, which is a flow diagram of the anode gas in the cyclic discharge step in FIG. 2, it can be seen from FIG. 4B that the gas in the anode 111 is discharged from the anode outlet 117 and then passed through the gas pushing device 121. Pushing through the recovery valve 122, mixing with fresh fuel, and then entering the anode 111 from the gas inlet 116, thereby circulating. The "circulation" in the aforementioned cyclic discharge step means that the anode 111 is in a gas circulation state.

Specifically, when the step 310 is performed, the control module 160 synchronously monitors the variation feature value. When the variation feature value is greater than the preset critical feature value, the process proceeds to step 310, and when the variation feature value is less than or equal to the preset threshold. In the characteristic value, it is indicated that the region of the anode 111 close to the gas outlet 117 accumulates excessive impurities, and the current density of the second block 114b is too low. At this time, the gas pushing device 121 and the recovery valve 122 are turned on, and the anode 111 is in a gas circulation state, and proceeds to step 330, whereby impurities in the anode 111 are not accumulated in the region where the anode 111 approaches the gas outlet 117, and Second block The current density of 114b rises back to restore the performance of the fuel cell unit 110.

Step 340 is a gas compression step that closes the recovery valve 122 to compress the gases in the gas push device 121 and the recovery valve 122. Referring to FIG. 4C, which is a flow diagram of the anode gas in the gas compression step in FIG. 2, it can be seen from FIG. 4C that at this time, the gas pushing device 121 is in an open state, which continuously supplies the gas in the anode 111. Withdrawn, the recovery valve 122 is in a closed state, so the gas in the gas push device 121 and the recovery valve 122 is continuously compressed. Step 340 is performed after step 330 is continued for a period of time. Since the anode 111 is in a gas circulation state in step 330, the impurities in the anode 111 are also evenly distributed. At this time, the impurity cannot be judged by monitoring the current density of the second block 114b. The degree of accumulation is so that it is necessary to switch to step 340 to stop the gas circulation state, which is advantageous for judging the degree of accumulation of impurities and increasing the efficiency of judging the degree of accumulation of impurities. Since the fuel cell unit 100 is connected to different loads 200, the rate at which the impurities are generated is different. Therefore, the aforementioned "continuation period" can be elastically adjusted according to the different loads 200. According to an embodiment of the invention, step 340 can be performed after step 60 continues for 60 minutes.

Step 350 is to perform a second monitoring step of monitoring the variation characteristic value. When the variation characteristic value is less than or equal to the critical characteristic value, the exhaust valve 130 is opened to connect the anode 111 to the outside. Please refer to FIG. 4D for cooperation, which is a schematic diagram of the flow of anode gas when the exhaust valve 130 is opened in FIG. 2 . As can be seen from Fig. 4D, at this time, the gas pushing device 121 and the exhaust valve 130 are in an open state, and the recovery valve 122 is in a closed state, whereby impurities in the anode 111 can be discharged, and the performance of the fuel cell unit 110 can be restored. With another The gas pushing device 121 can accelerate the speed at which the impurity gas is discharged from the anode 111, and can further prevent the exhaust valve 130 from being opened for a long time to cause waste of fuel. Specifically, when the step 340 is performed, the control module 160 synchronously monitors the variation feature value. When the variation feature value is greater than the preset critical feature value, it indicates that the impurity accumulation degree is slight, and it is not necessary to open the exhaust valve 130. Returning to step 330, the cyclic discharge is continued, and when the variation characteristic value is less than or equal to the preset critical characteristic value, it indicates that the anode 111 has accumulated excessive impurities; at this time, the exhaust valve 130 is opened, and the impurity in the anode 111 is turned on. The purification function is achieved by discharging to the outside, and the performance of the fuel cell unit 110 can be restored. After the anode 111 is cleaned, it is returned to step 310 to continuously manage the anode gas using the gas management method 300 of the anode circulating fuel cell.

Figure 5 is a flow chart showing the steps of a method 500 for setting a critical feature value in accordance with yet another embodiment of the present invention. The method of setting the critical characteristic value 500 will be specifically described below with the gas management system 100 and the load 200 of the anode circulating fuel cell of FIG. The critical feature value setting method 500 includes step 510 and step 520.

Step 510 is to perform a predetermined closed discharge step of discharging the fuel cell unit 110 at a preload current density and a preload voltage when the gas push device 121, the exhaust valve 130, and the recovery valve 122 are closed.

Step 520 is a voltage monitoring step of monitoring the preload voltage. When the preload voltage drops by a voltage threshold, the current density of the second block 114b is measured as the critical current density, and the critical current density and the preload current density are measured. The ratio is used as the critical eigenvalue.

Specifically, the preload current density is the current density provided by the fuel cell unit 110 as a whole, that is, the total current of the fuel cell unit 110 measured by the first current sensor 140 is calculated by the control module 160. The overall current density of the battery unit 110. The preload voltage is the voltage supplied by the fuel cell unit 110 as a whole. The initial value of the preload voltage depends on the preload current density and the type of the load 200. During the discharge process, the preload voltage gradually decreases due to the accumulation of impurities, and the preload is preloaded. The voltage can be measured by the control module 160. For example, when the control module 160 is a data capture card installed on a computer, the preload voltage can be obtained through the data capture card. The voltage threshold is a tolerance value of the magnitude of the output voltage of the fuel cell unit 110 during the discharge process. When the preload voltage decreases by a magnitude equal to or greater than the voltage threshold, the performance of the fuel cell unit 110 has decreased too much, and appropriate Gas management to restore performance of the fuel cell unit 110. Based on different loads 200, the magnitude of the voltage change that can be withstand is different. Therefore, the voltage threshold can be set according to actual needs. According to an embodiment of the invention, the voltage threshold is 0.1V, but the invention is not limited thereto. Therefore, the gas management method 300 of the anode circulating fuel cell of the present invention can be tailored to a suitable critical characteristic value depending on the type of the load 200, thereby facilitating the gas management method of the anode circulating fuel cell of the present invention. The breadth of application of 300.

It can be seen from the above description that the gas management system of the anode circulating fuel cell according to the present invention has the advantages of simple structure, and only needs to divide the anode conductive plate into the first block and the second block, and then install the exhaust valve. Recycling valves and gas pushers are beneficial for use in fuel cells that are commonly used today. In addition, gas management of an anode circulating fuel cell according to the present invention The method is beneficial for determining the opening timing of the exhaust valve and reducing the opening frequency of the exhaust valve, thereby greatly improving energy efficiency.

<Example 1>

First, a gas management system 100 for an anode circulating fuel cell is constructed according to FIG. 1 and a load 200 is connected, as shown in FIG. 2, wherein the fuel cell unit 110 is a proton exchange membrane fuel cell, and the fuel cell unit The reaction area of 110 was 125 cm ² . The gas pushing unit 121 is a gas pump (the brand is KNF); the model number is NMP015S. The exhaust valve 130 and the recovery valve 122 are solenoid valves (brand name is Burker, Germany; model number 6126), and the control module 160 is NI 9219 produced by National Instruments Corporation, and hydrogen gas is used as fuel to the anode 111. Air is supplied to the cathode 113 as a combustion improver. However, in conducting the experiment, in order to understand the change in current density of each portion in the interior of the anode 111, the conductive plate 114 of the anode 111 was replaced. Please refer to FIG. 6 , which is a schematic diagram of a conductive plate 600 used in the anode 111 of the embodiment 1. The conductive plate 600 is a graphite conductive plate, which comprises 20 wires 610 , and the wires 610 are fixed on the conductive plate 600 with silver glue 620 . The individual wires 610 are connected in parallel with each other. Each of the wires 610 is connected to a current sensor (the connection mode is the same as that of the second sensor 150 and the second block 114b), and then connected to the control module 160, that is, the anode 111 is tested during the experiment. The conductive plate 600 is divided into 20 blocks instead of the two blocks (the first block 114a and the second block 114b) of the conductive plate 114 as shown in FIG. Thereby, the current density of the anode 111 at different positions along the gas inlet 116 to the gas outlet 117 can be detected.

The experimental conditions of Example 1 were as follows: The operating temperature of the fuel cell unit 110 was 65 ° C, the output fixed current was 60 A (the equivalent current density was 0.48 Acm ^-2 ), and the voltage threshold was 0.1 V.

Please refer to Figures 7A and 7B. 7A is a graph of voltage vs. time of the embodiment 1. The voltage refers to the output voltage of the fuel cell unit 110, which can be measured by the control module 160. The voltage is expressed in volts (V), and the time refers to the fuel cell unit 110. The operating time, the unit of time is minutes (min). 7B is a graph showing the normalized current density, position versus time of Embodiment 1, wherein the normalized current density refers to the ratio of the current density of the single wire 610 to the overall current density of the fuel cell unit 110, and the position 1 to 20 is Corresponding to the 20 blocks of the conductive plate 600, the block closest to the gas inlet 116 is 1 and the block closest to the gas outlet 117 is 20, and the time refers to the operation time of the fuel cell unit 110, and the time is in minutes. (min). In FIGS. 7A and 7B, the closure refers to a closed discharge step, the cycle refers to a cyclic discharge step, the compression refers to a gas compression step, and the exhaust refers to the opening of the exhaust valve 130. As shown in FIGS. 7A and 7B, Example 1 is sequentially subjected to a closed discharge step of about 30 minutes, a cyclic discharge step of about 30 minutes, a gas compression step of about 20 minutes, exhaust, and further about. A 30 minute closed discharge step, a 60 minute cyclic discharge step, a 20 minute gas compression step, and an exhaust gas, wherein the time of the two cyclic discharge steps is different, is to observe the difference caused by the difference in the cycle discharge time.

As can be seen from FIGS. 7A and 7B, when the closed discharge step is performed, impurities are easily accumulated in the vicinity of the gas outlet 117, resulting in a large difference in the normalized current density between the gas inlet 116 and the gas outlet 117, resulting in a fuel cell unit. The output voltage of 110 is lowered, and the output voltage of the fuel cell unit 110 can be raised by the cyclic discharge step, however, due to the impurity accompanying the gas In the systemic circulation, it is impossible to judge the accumulation of impurities in the anode 111 by the normalized current density (the difference in the normalized current density at different positions in the cyclic discharge step is small), and the gas compression step is advantageous for judging impurities. The degree of accumulation (the normalized current density of the gas inlet 116 and the gas outlet 117 is greatly different in the gas compression step). It can be seen from FIGS. 7A and 7B that when the voltage drop of the fuel cell unit 110 is large, the normalized current density near the gas outlet 117 is also significantly reduced, and it is apparent that the normalized current density near the gas outlet 117 can be used as a fuel. The indicator of the voltage drop of the battery unit 110. Therefore, according to the gas management method of the anode circulation type fuel cell of the present invention, the normalized current density close to the gas outlet 117 block (corresponding to the second block 114b) is used as the variation characteristic value as the monitored object, and It is not necessary to monitor the normalized current density of other blocks, so it is only necessary to divide the conductive plate 114 into the first block 114a and the second block 114b, without dividing into 20 blocks as in Embodiment 1, so the present invention The gas management method of the anode circulating fuel cell has a simple advantage. Furthermore, comparing the two-cycle discharge step in FIG. 7A, the first-cycle discharge step performs a gas compression step only for 30 minutes, and the voltage at the time of exhaust and the initial voltage (time is 0) The difference is not large, indicating that the accumulation of impurities in the fuel cell unit 110 at the time of the first exhaust is still slight, and the time for opening the exhaust valve 130 can be further extended. Therefore, when the experiment is continued, the second cyclic discharge is elongated. The time of the step, while comparing the voltage at the second exhaust and the initial voltage, the difference is still within the preset voltage threshold of 0.1V, indicating that the accumulation of impurities in the fuel cell unit 110 during the second exhaust is still not Seriously, the time to open the exhaust valve 130 can be delayed, that is, the opening period of the exhaust valve 130 of Embodiment 1 (closed The sum of the discharge step, the cyclic discharge step and the gas compression step can be at least 110 minutes or more, in other words, the opening frequency of the exhaust valve 130 can be greatly reduced.

<Comparative Example 1>

Comparative Example 1 is a gas management system for an anode-closed fuel cell. Compared with the gas management system of the anode-circulating fuel cell of the present invention, Comparative Example 1 lacks a gas circulation unit, so that fuel that does not participate in the reaction cannot be recovered and reused.

Please refer to FIG. 8, which is a schematic diagram of a gas management system 800 for an anode-closed fuel cell according to Comparative Example 1 of the present invention. The gas management system 800 for an anode-enclosed fuel cell includes a fuel cell unit 810, an exhaust valve 830, a first current sensor 840, a second current sensor 850, and a control module 860. The fuel cell unit 810 includes an anode 811, a gas inlet 816, and a gas outlet 817. The anode 811 includes a conductive plate 814. The conductive plate 814 includes a first block 814a and a second block 814b. The first block 814a corresponds to the gas inlet 816. The second block 814b corresponds to the gas outlet 817. The gas management system 800 of the anode-enclosed fuel cell differs from the gas management system 100 of the anode-circulating fuel cell of FIG. 1 only in that the gas management system 800 of the anode-enclosed fuel cell lacks the gas circulation unit 120, and the rest of the details are the same. I will not repeat them here.

When conducting the experiment, first, a gas management system 800 for an anode-enclosed fuel cell is constructed according to Fig. 8 and a load (not shown) is connected. Moreover, as in Embodiment 1, the conductive plate 814 is replaced with the conductive plate 600 of FIG. 6 to facilitate detection of the anode 811 along the gas inlet 816 to the gas. The current density at different locations of the body outlet 817. The types and specifications of the components in the gas management system 800 for the anode-enclosed fuel cell can be the same as in the first embodiment, and will not be further described herein.

The experimental conditions of Comparative Example 1 were as follows: the operating temperature of the fuel cell unit 810 was 65 ° C, and the output fixed current was 30 A (corresponding current density was 0.24 Acm ^-2 ), and the output fixed current was 40 A (corresponding current density was 0.32 Acm ^-2 ). The experiment was conducted by outputting a fixed current of 50 A (corresponding to a current density of 0.4 Acm ^-2 ).

Please refer to FIG. 9A and FIG. 9B. FIG. 9A is a graph showing voltage versus time of different current densities of Comparative Example 1. Voltage refers to the output voltage of the fuel cell unit 810, and the unit of voltage is volt (V), time. It refers to the operation time of the fuel cell unit 810, and the unit of time is minutes (min). Figure 9B is a graph of current density, position versus time for different current densities in Comparative Example 1, wherein current density refers to the current density of each wire 610, and positions 1 to 20 correspond to 20 blocks of the conductive plate 600, The block closest to the gas inlet 816 is 1 and the block closest to the gas outlet 817 is 20, and time refers to the operating time of the fuel cell unit 810 in units of minutes (min).

In FIGS. 9A and 9B, the closing means performing a closed discharge step, that is, discharging when the exhaust valve 830 is closed, and exhausting means opening the exhaust valve 830. As shown in FIGS. 9A and 9B, when the fuel cell unit 810 is of a closed type, the current density distribution inside the anode 811 is very uneven, and the life of the fuel cell unit 810 is easily broken for a long period of time.

Further, Comparative Example 1 was tested under the following conditions. The operating temperature of the fuel cell unit 810 was 65 ° C, and a fixed current of 60 A (a relative current density of 0.48 Acm ^-2 ) was obtained, respectively, and FIGS. 10A and 10B were obtained. Fig. 10A is a graph showing another voltage versus time of Comparative Example 1, and Fig. 10B is a graph showing the relationship between normalized current density, position and time of Comparative Example 1, and in Figs. 10A and 10B, the time is in seconds. As a unit, the definition of the remaining coordinates may be the same as that of FIGS. 7A and 7B, and will not be further described herein. It can be seen from FIGS. 10A and 10B that if the voltage threshold is equal to 0.1 V as a reference, the exhaust valve 830 is required to open the exhaust gas for about 30 minutes, compared with the gas management system of the anode circulating fuel cell of the present invention. The cycle of opening the exhaust valve 830 is too short, that is, the opening frequency is too high, the fuel is easily wasted, and the energy efficiency is not good.

It should be noted that the intention of Embodiment 1 of the present invention is to verify whether the method of the present invention can effectively manage the anode gas. Therefore, the conductive plate 600 of the anode 111 of Embodiment 1 of the present invention is divided into 20 blocks; As previously mentioned, in practice, it is only necessary to observe the normalized current density near the gas outlet 117 block (corresponding to the second block 114b). In other words, Embodiment 1 of the present invention is a verification result of whether or not the present invention is effective.

In summary, the gas management method and system for the anode circulating fuel cell according to the present invention can avoid the anode of the fuel cell unit from being uneven in current density for a long period of time compared with the gas management method and system for the anode-closed fuel cell. The condition can prolong the service life and extend the cycle of opening the exhaust valve to avoid fuel waste and improve energy efficiency. Furthermore, the gas management method and system for the anode circulation type fuel cell according to the present invention can solve the problem that the anode cannot be judged when the anode is in the gas circulation state, and the timing of opening the exhaust valve cannot be judged, and the anode cycle is conventionally used. Gas management method for fuel cell compared with system, anode circulating fuel cell of the invention The gas management method and system of the pool has the advantages of simple structure and method, and is beneficial to the fuel cell commonly used today.

While the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and the invention may be modified and modified in various ways without departing from the spirit and scope of the invention. The scope is subject to the definition of the scope of the patent application.

Claims (10)

A gas management method for an anode circulating fuel cell is applied to an anode circulating fuel cell, wherein the anode circulating fuel cell comprises a fuel cell unit, the fuel cell unit comprises an anode, and the anode comprises a conductive plate, the conductive The plate includes a first block and a second block, wherein the first block corresponds to a gas inlet, and the second block corresponds to a gas outlet. The gas management method of the anode circulating fuel cell comprises: performing a closed The discharging step is to discharge the fuel cell unit when a gas pushing device, an exhaust valve and a recovery valve are closed; performing a first monitoring step of monitoring a variable characteristic value when the variation characteristic value is less than Or equal to a predetermined critical characteristic value, the gas pushing device and the recovery valve are turned on, wherein the variation characteristic value is a ratio of a current density of the second block to an overall current density of the fuel cell unit; performing a cycle The discharging step is performed when the gas pushing device and the recovery valve are opened and the exhaust valve is closed The unit performs discharging; performing a gas compression step of closing the recovery valve to compress a gas in the gas pushing device and the recovery valve; and performing a second monitoring step to monitor the variation characteristic value when the variation characteristic When the value is less than or equal to the critical characteristic value, the exhaust valve is opened to cause the anode to communicate with the outside. The gas management method for an anode circulating fuel cell according to claim 1, wherein the method for setting the critical characteristic value The method includes: performing a predetermined closed discharge step of discharging the fuel cell unit at a preload current density and a preload voltage when the gas push device, the exhaust valve, and the recovery valve are closed; and performing a voltage monitoring step of monitoring the preload voltage, and when the preload voltage drops by a voltage threshold, measuring the current density of the second block as a critical current density, and using the critical current density and the preload current The ratio of the density is taken as the critical characteristic value. The gas management method for an anode circulating fuel cell according to claim 2, wherein the voltage threshold is 0.1 volt. The gas management method for an anode circulating fuel cell according to claim 1, wherein the gas pushing device is a gas pump. The gas management method for an anode circulating fuel cell according to claim 1, wherein the fuel cell unit is a proton exchange membrane fuel cell. A gas management system for an anode circulating fuel cell, comprising: an anode circulating fuel cell, comprising: a fuel cell unit comprising an anode, a gas inlet and a gas outlet, wherein the anode comprises a conductive plate, the conductive plate contain a first block corresponding to the gas inlet, the second block corresponding to the gas outlet; a gas circulation unit connecting the gas inlet and the gas outlet, the gas circulation unit A gas pushing device and a recovery valve are disposed between the gas outlet and the gas inlet for providing a power of a gas in the anode flowing from the gas outlet to the gas inlet, the recycling a valve is disposed between the gas pushing device and the gas inlet; and an exhaust valve is disposed between the gas pushing device and the recovery valve; a first current sensor is configured to measure the fuel cell unit An overall current; a second current sensor for measuring the current of the second block; and a control module connecting the first current sensor, the second current sensor, the gas pushing device, The exhaust valve and the recovery valve, the control module stores a critical characteristic value, and the control module receives the current of the second block current and the overall current of the fuel cell unit and calculates the first The ratio of the block current density to the overall current density of the fuel cell unit is used as a variation characteristic value, and the control module controls the gas push device, the exhaust valve, and the control feature to control the closed feature value and the critical feature value. Recycle the valve. The gas management system for an anode circulating fuel cell according to claim 6, wherein the control module compares the fluctuation characteristic value and the gas pumping device, the exhaust valve and the recovery valve when the gas valve is closed Critical characteristic value, when the variation characteristic value is less than or equal to the critical value When the characteristic value is reached, the gas pushing device and the recovery valve are opened to put the anode in a gas circulation state. The gas management system for an anode circulating fuel cell according to claim 6, wherein the control module compares the fluctuation characteristic value when the gas pushing device is opened, the exhaust valve and the recovery valve are closed, and The critical characteristic value is opened when the fluctuation characteristic value is less than or equal to the preset critical characteristic value, so that the anode is in communication with the outside. The gas management system for an anode circulating fuel cell according to claim 6, wherein the gas pushing device is a gas pump. The gas management system for an anode circulating fuel cell according to claim 6, wherein the fuel cell unit is a proton exchange membrane fuel cell.