Closed cathode structure of air-cooled fuel cell and fuel cell system

Abstract

Provided in the present invention are a closed cathode structure of an air-cooled fuel cell and a fuel cell system. The structure comprises an air inlet and a hydrogen outlet / inlet arranged on the left side, and a hydrogen inlet / outlet and an air outlet arranged on the right side, wherein the middle part between the two sides is a reaction zone in which an anode hydrogen flow channel, a cathode air flow channel and a heat dissipation air flow channel are provided; the reaction area comprises a hydrogen reaction zone and an air reaction zone; an air inlet of the cathode air flow channel is close to a heat dissipation air inlet of the heat dissipation air flow channel; and an air outlet of the cathode air flow channel is close to a heat dissipation air outlet of the heat dissipation air flow channel. The closed cathode structure of the air-cooled fuel cell and the fuel cell system optimize the hydrothermal balance layout, eliminate a wet-cold area and a dry-hot area, improve the utilization efficiency of a catalyst and a proton exchange membrane, and increase the current density.

Description

Air-cooled fuel cell cathode closed structure and fuel cell system TECHNICAL FIELD

[0001] The present application relates to a fuel cell, in particular to an air-cooled fuel cell cathode closed structure and fuel cell system. BACKGROUND

[0002] Fuel cells use hydrogen as energy to generate electricity, and the reaction product is water, with high energy conversion efficiency, and are a new environmentally friendly and efficient energy source. Although the energy conversion efficiency of fuel cells is higher than that of internal combustion engines, a considerable amount of waste heat is still generated. The waste heat is discharged in two ways, through water or antifreeze cooling, and through air cooling. In the case of air cooling, the internal structure and peripheral structure of the fuel cell are relatively simple because the cooling liquid circulation system and external radiator are not needed, so it is very suitable for small power applications.

[0003] In the case of air cooling, fuel cells can also have two different structures, cathode closed and cathode open. The fuel cell with cathode closed structure only uses a flow of cooling air instead of a flow of cooling liquid, and still retains a separate flow of reaction air provided to the cathode. The fuel cell with cathode open structure directly obtains the air required for reaction from the flow of cooling air, so the structure is more compact. However, the fuel cell with cathode open structure is not convenient to set up a chemical filter for the reaction air flow, and its upper and lower limits of ambient temperature are also relatively narrow, and the current density that can be achieved is smaller, and the current density involves the utilization rate of the membrane electrode with the largest cost proportion.

[0004] Because the air-cooled fuel cell with cathode closed structure has the advantages of both liquid cooling and cathode open structure, it is very suitable for small power and harsh environment scenarios, and has a wide application prospect. However, in actual product development, the air-cooled fuel cell with cathode closed structure has a current density that is still slightly lower than that of the liquid-cooled fuel cell. For example, a designed liquid-cooled fuel cell has a cathode outlet without back pressure, a cathode air metering ratio of 2.0, and a stack core temperature of about 65 degrees, and the current density achieved is 1.2 A / cm2@0.65V; while another designed air-cooled fuel cell with cathode closed structure based on the mainstream scheme of the same industry (as shown in FIGS. 1-3), uses the same membrane electrode configuration as the former, and the same operating conditions, the current density is only 1.0 A / cm2@0.65V, which leads to an increase in the cost of the core component membrane electrode.

[0005] As shown in Fig. 1 to Fig. 3, the reaction zone of the cathode closed structure of the air-cooled fuel cell is provided with three air flow channels, namely the anode hydrogen flow channel, the heat dissipation air flow channel and the cathode air flow channel. The right end of the air-cooled fuel cell is provided with two hydrogen inlets (hydrogen inlets) and an air outlet (air outlet), and the air outlet is located between the two hydrogen inlets. The left end is provided with two hydrogen outlets (hydrogen outlets) and an air inlet (air inlet), and the air inlet is located between the two hydrogen outlets. The anode hydrogen flow channel between the hydrogen inlet and the hydrogen outlet is used for passing hydrogen, the cathode air flow channel between the air inlet and the air outlet is used for passing air, and the direction of the anode hydrogen flow channel is opposite to that of the cathode air flow channel. The heat dissipation air flow channel is used for passing air from bottom to top, which is perpendicular to the directions of the anode hydrogen flow channel and the cathode air flow channel. SUMMARY

[0006] The application provides a cathode closed structure of an air-cooled fuel cell and a fuel cell system, which solves the problem of improving the current density of the cathode closed structure of the air-cooled fuel cell.

[0007] A cathode closed structure of an air-cooled fuel cell, comprising an air inlet, a hydrogen inlet / outlet arranged on the left side, a hydrogen inlet / outlet, an air outlet arranged on the right side, and a reaction zone with an anode hydrogen flow channel, a cathode air flow channel and a heat dissipation air flow channel arranged in the middle of the two sides. The reaction zone comprises a hydrogen reaction zone and an air reaction zone.

[0008] The hydrogen reaction zone comprises a hydrogen inlet flow channel zone, a hydrogen middle flow channel zone and a hydrogen outlet flow channel zone. The anode hydrogen flow channel of the hydrogen inlet flow channel zone and the anode hydrogen flow channel of the hydrogen outlet flow channel zone are arranged in parallel, and the anode hydrogen flow channel of the hydrogen middle flow channel zone is perpendicular to the anode hydrogen flow channels of the hydrogen inlet flow channel zone and the hydrogen outlet flow channel zone.

[0009] The air reaction zone comprises an air inlet flow channel zone, an air middle flow channel zone and an air outlet flow channel zone. The cathode air flow channel of the air inlet flow channel zone and the cathode air flow channel of the air outlet flow channel zone are arranged in parallel, and the cathode air flow channel of the air middle flow channel zone is perpendicular to the cathode air flow channels of the air inlet flow channel zone and the air outlet flow channel zone.

[0010] The air inlet of the cathode air flow channel is close to the heat dissipation air inlet of the heat dissipation air flow channel, and the air outlet of the cathode air flow channel is close to the heat dissipation air outlet of the heat dissipation air flow channel.

[0011] The area of the hydrogen middle flow channel zone is greater than 50% of the area of the hydrogen reaction zone.

[0012] The area of the air middle flow channel zone is greater than 50% of the area of the air reaction zone.

[0013] When the air inlet and the hydrogen outlet are arranged on the left side of the cathode closed structure of the air-cooled fuel cell, and the hydrogen inlet and the air outlet are arranged on the right side of the cathode closed structure of the air-cooled fuel cell, the hydrogen inlet of the anode hydrogen flow channel is close to the heat dissipation air outlet of the heat dissipation air flow channel; and the hydrogen outlet of the anode hydrogen flow channel is close to the heat dissipation air inlet of the heat dissipation air flow channel.

[0014] The anode hydrogen flow channel of the hydrogen middle flow channel area is parallel to the heat dissipation air flow channel, and the cathode air flow channel of the air middle flow channel area is parallel to the heat dissipation air flow channel.

[0015] The first separation line between the hydrogen inlet flow channel area and the hydrogen middle flow channel area is arranged obliquely from top to bottom, and the second separation line between the hydrogen outlet flow channel area and the hydrogen middle flow channel area is parallel to the first separation line, and the height of the first separation line and the second separation line close to the position of the air outlet is higher than the height of the first separation line and the second separation line close to the position of the air inlet.

[0016] The third separation line between the air inlet flow channel area and the air middle flow channel area is arranged obliquely from top to bottom, and the fourth separation line between the air outlet flow channel area and the air middle flow channel area is parallel to the third separation line, and the height of the third separation line and the fourth separation line close to the position of the hydrogen outlet is higher than the height of the third separation line and the fourth separation line close to the position of the hydrogen inlet.

[0017] The shape of the hydrogen middle flow channel area and the air middle flow channel area is a parallelogram.

[0018] The air inlet is located below the hydrogen outlet, and the hydrogen inlet is located below the air outlet.

[0019] The right end of the anode hydrogen flow channel is connected to the hydrogen inlet, and the left end of the anode hydrogen flow channel is connected to the hydrogen outlet; the left end of the cathode air flow channel is connected to the air inlet, and the right end of the cathode air flow channel is connected to the air outlet.

[0020] A fuel cell system adopts the cathode closed structure of the air-cooled fuel cell described in any one of the above, and a fan is arranged outside the cathode closed structure of the air-cooled fuel cell.

[0021] The fuel cell system comprises a heat dissipation fan, and the airflow flow direction of the heat dissipation fan is consistent with the flow direction of the fuel cell heat dissipation air flow; and a cathode fan, and the airflow flow direction of the cathode fan is consistent with the flow direction of the fuel cell cathode air flow.

[0022] Further, the heat dissipation fan adopts an axial flow fan, and the cathode fan adopts a centrifugal fan.

[0023] The air-cooled fuel cell with the cathode closed structure and the fuel cell system optimize the water-heat balance layout, eliminate the wet and dry heat areas, improve the utilization efficiency of the catalyst and the proton exchange membrane, and improve the current density. BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 is a schematic diagram of the anode overall layout structure of the air-cooled fuel cell with the cathode closed structure;

[0025] Fig. 2 is a schematic diagram of the heat dissipation overall layout structure of the air-cooled fuel cell with the cathode closed structure;

[0026] Fig. 3 is a schematic diagram of the cathode overall layout structure of the air-cooled fuel cell with the cathode closed structure;

[0027] Fig. 4 is a schematic diagram of the anode overall layout structure of the air-cooled fuel cell with the cathode closed structure in embodiment 1;

[0028] Fig. 5 is a schematic diagram of the cooling overall layout structure of the air-cooled fuel cell with the cathode closed structure in embodiment 1;

[0029] Fig. 6 is a schematic diagram of the cathode overall layout structure of the air-cooled fuel cell with the cathode closed structure in embodiment 1;

[0030] Fig. 7 is a schematic diagram of the partial perspective structure of the air-cooled fuel cell with the cathode closed structure;

[0031] Fig. 8 is a schematic diagram of the anode overall layout structure of the air-cooled fuel cell with the cathode closed structure in embodiment 2;

[0032] Fig. 9 is a schematic diagram of the cooling overall layout structure of the air-cooled fuel cell with the cathode closed structure in embodiment 2;

[0033] Fig. 10 is a schematic diagram of the cathode overall layout structure of the air-cooled fuel cell with the cathode closed structure in embodiment 2;

[0034] Fig. 11 is a schematic diagram of the heat dissipation fan arrangement of the fuel cell system;

[0035] Fig. 12 is a schematic diagram of the cathode fan arrangement of the fuel cell system;

[0036] Fig. 13 is a bottom view of the single cell cathode plate;

[0037] Fig. 14 is a top view of the single cell anode plate. DETAILED DESCRIPTION

[0038] In the air-cooled fuel cell of the cathode closed structure shown in Fig. 1, the shape of the reaction zone is rectangular, the left-right direction between the hydrogen inlet and the hydrogen outlet (or the air inlet and the air outlet) is defined as the long side, and the up-down direction of the heat dissipation air flow channel is defined as the short side. After in-depth and detailed research and analysis of the prior art air-cooled fuel cell, it is found that because the specific heat capacity of air is small and the ability to absorb heat by heating is weak, in order to avoid too large wind pressure leading to too large power consumption and too large wind noise, the length of the heat dissipation air flow channel must be small, so the heat dissipation air flow channel needs to be parallel to the short side of the shape of the fuel cell, thereby forming a vertical relationship with the cathode air flow channel parallel to the long side of the shape of the fuel cell.

[0039] In the reaction zone of the air-cooled fuel cell, the air flowing from left to right constantly absorbs water vapor generated by the reaction, and the absolute humidity constantly increases. In the lower right corner of the reaction zone, the relatively cold heat dissipation air just entering cooperates with the cathode air flow that has absorbed a large amount of water vapor generated by the reaction to generate a relatively wet and cold wet and cold area, and the catalyst in this area is flooded, causing a local current density to decrease; while in the upper left corner of the reaction zone, the relatively hot heat dissipation air flow that is close to the full course cooperates with the relatively dry cathode air flow that has just entered to generate a relatively dry and hot dry and hot area, and the proton exchange membrane in this area is blown dry, causing the proton conductivity to decrease, also causing a local current density to decrease.

[0040] Based on the above research and analysis, the present application proposes a cathode closed structure of an air-cooled fuel cell, as shown in Embodiment 1 of Figs. 4 to 6, including an air inlet arranged on the left side, a hydrogen outlet, a hydrogen inlet arranged on the right side, and an air outlet, and a reaction zone with an anode hydrogen flow channel, a cathode air flow channel, and a heat dissipation air flow channel arranged in the middle of the two sides; the right end of the anode hydrogen flow channel is connected to the hydrogen inlet, and the left end is connected to the hydrogen outlet; the left end of the cathode air flow channel is connected to the air inlet, and the right end is connected to the air outlet. On the left side of the cathode closed structure of the air-cooled fuel cell, the air inlet is located below the hydrogen outlet, and on the right side of the cathode closed structure of the air-cooled fuel cell, the hydrogen inlet is located below the air outlet. The heat dissipation air inlet of the heat dissipation air flow channel is located below, and the heat dissipation air outlet is located above. Although the two areas of the anode overall layout structure provided in Fig. 4 and the cathode overall layout structure provided in Fig. 6 are projected to overlap, they are located on the upper and lower different layers of the proton exchange membrane 15, and are therefore air-tight with each other.

[0041] The reaction zone includes hydrogen reaction zone and air reaction zone, figure 4 shows the anode overall layout corresponding to hydrogen reaction zone, hydrogen reaction zone includes hydrogen inlet channel area 1, hydrogen middle channel area 2 and hydrogen outlet channel area 3, the anode hydrogen flow channel of hydrogen inlet channel area 1 and the anode hydrogen flow channel of hydrogen outlet channel area 3 are arranged in parallel, the anode hydrogen flow channel of hydrogen middle channel area 2 is perpendicular to the anode hydrogen flow channel of hydrogen inlet channel area 1 and hydrogen outlet channel area 3; Figure 5 shows the cooling overall layout corresponding to the heat dissipation air flow channel, the heat dissipation air flows from bottom to top; Figure 6 shows the cathode overall layout corresponding to the air reaction zone, the air reaction zone includes air inlet channel area 4, air middle channel area 5 and air outlet channel area 6, the cathode air flow channel of air inlet channel area 4 and the cathode air flow channel of air outlet channel area 6 are arranged in parallel, the cathode air flow channel of air middle channel area 5 is perpendicular to the cathode air flow channel of air inlet channel area 4 and air outlet channel area 6.

[0042] Further, the anode hydrogen flow channel of hydrogen middle channel area 2 is parallel and same direction to the heat dissipation air flow channel, the cathode air flow channel of air middle channel area 5 is parallel to the heat dissipation air flow channel. In the embodiment, the area of the hydrogen middle channel area 2 is greater than 50% of the hydrogen reaction zone, so that the anode hydrogen flow is parallel and same direction to the heat dissipation air flow in more than 50% of the hydrogen reaction zone. Preferably, the area of the hydrogen middle channel area 2 is greater than 70% of the hydrogen reaction zone, so that the anode hydrogen flow is parallel and same direction to the heat dissipation air flow in more than 70% of the hydrogen reaction zone.

[0043] Further, the area of the cathode air flow channel of air middle channel area 5 is greater than 50% of the air reaction zone, so that the cathode air flow is parallel and same direction to the heat dissipation air flow in more than 50% of the air reaction zone. Preferably, the area of the air middle channel area 5 is greater than 70% of the air reaction zone, so that the cathode air flow is parallel and same direction to the heat dissipation air flow in more than 70% of the air reaction zone.

[0044] The greater the proportion of the hydrogen middle channel area 2 and air middle channel area 5, the better the hydrothermal balance effect, through the 90 degree turning of the anode hydrogen flow channel and the cathode air flow channel, the anode hydrogen flow, the cathode air flow and the heat dissipation air flow are parallel or even same direction. Further, parallel and same direction can play a better effect, and parallel reverse can also be realized according to the actual situation.

[0045] The first separation line of hydrogen inlet channel area 1 and hydrogen middle channel area 2 is arranged obliquely from top to bottom, the second separation line of hydrogen outlet channel area 3 and hydrogen middle channel area 2 is parallel to the first separation line, through the first separation line, the second separation line and the separation line on the left and right sides of hydrogen middle channel area 2, the shape of hydrogen middle channel area 2 is parallelogram. The first separation line and the second separation line are close to the position height of the air outlet, which is higher than the position height close to the air inlet.

[0046] Similarly, the third separation line of the air inlet channel area 4 and the air middle channel area 5 is arranged obliquely from top to bottom, the fourth separation line of the air outlet channel area 6 and the air middle channel area 5 is parallel to the third separation line, and the third separation line, the fourth separation line and the separation lines on the left and right sides of the air middle channel area 5 make the shape of the air middle channel area 5 a parallelogram. The third separation line and the fourth separation line are higher in height near the hydrogen outlet than in height near the hydrogen inlet.

[0047] Through the above arrangement, the air inlet of the cathode air flow channel and the hydrogen inlet of the anode hydrogen flow channel are close to the heat dissipation air inlet of the heat dissipation air flow channel, so that the inlet area becomes a dry and cold area, neither easy to flood the catalyst nor easy to dry the proton exchange membrane. The air outlet of the cathode air flow channel and the hydrogen outlet of the anode hydrogen flow channel are close to the heat dissipation air outlet of the heat dissipation air flow channel, so that the outlet area becomes a wet and hot area, neither easy to flood the catalyst nor easy to dry the proton exchange membrane.

[0048] Further, the groove depth of the air middle channel area 5 perpendicular to the heat dissipation air flow channel is at least twice the groove depth of the air inlet channel area 4 and / or the air outlet channel area 6 parallel to the heat dissipation air flow channel.

[0049] Further, the groove depth of the hydrogen middle channel area 2 perpendicular to the heat dissipation air flow channel is at least twice the groove depth of the hydrogen inlet channel area 1 and / or the hydrogen outlet channel area 3 parallel to the heat dissipation air flow.

[0050] As shown in FIG. 7, in the embodiment of the present application, between the cathode air flow field plate 11 corresponding to the cathode air flow channel and the anode hydrogen flow field plate 13 corresponding to the anode hydrogen flow channel, a cathode gas diffusion layer 12, a proton exchange membrane 15 coated with a catalyst, and an anode gas diffusion layer 14 are sequentially arranged, and the gas enters the branch flow channel 16 of the flow field area of the electrode plate from the main flow channel through the trunk flow channel.

[0051] In the 75% area of the reaction area, the cathode air flow is parallel and co-directional with the heat dissipation air flow, and in the remaining 25% area, the cathode air flow is perpendicular to the heat dissipation air flow. In the 75% area of the reaction area, the anode hydrogen flow is parallel and co-directional with the heat dissipation air flow, and in the remaining 25% area, the anode hydrogen flow is perpendicular to the heat dissipation air flow.

[0052] In a small area near the inlet of the cooling air and near the outlet of the cooling air, the anode hydrogen flow and the cathode air flow are parallel and counter-current, which can slightly play the role of counter-current humidification, further optimizing the dry and wet distribution of the isothermal zone. It is well known to those skilled in the art that the downstream of the cathode air flow has a relatively high humidity, and the water produced by the reaction can penetrate to the anode side through the proton exchange membrane, and be carried by the reverse anode hydrogen flow to the upstream of the cathode air flow corresponding to the anode side with relatively low humidity, to compensate for the relatively dry problem of the proton exchange membrane.

[0053] The groove depth of the cathode air flow perpendicular to the cooling air flow is 2.5 times the groove depth of the cathode air flow parallel to the cooling air flow. As can be seen from the figure, the anode hydrogen flow channel and the cathode air flow channel, each main flow channel corresponds to 5 branch flow channels, and the flow rate is 5 times that of the branch flow channel, so a larger cross-sectional area is required.

[0054] Further, the groove depth of the anode hydrogen flow perpendicular to the cooling air flow is 2.5 times the groove depth of the anode hydrogen flow parallel to the cooling air flow.

[0055] Figure 7 shows the details of a single cell, including the cathode air flow field plate 11 and the anode hydrogen flow field plate 13. In order to obtain a high enough voltage and a large enough power, the actual fuel cell is usually composed of multiple single cells stacked into a stack. Therefore, 11 of the lower single cell and 13 of the upper single cell are bonded as a bipolar plate, and the flow channel between them is a cooling air flow channel.

[0056] In Example 2 shown in Figures 8 to 10, compared with Example 1, the difference is that the hydrogen outlet and the hydrogen inlet are exchanged.

[0057] The cathode closed structure of the air-cooled fuel cell includes an air inlet arranged on the left side, a hydrogen inlet, a hydrogen outlet and an air outlet arranged on the right side, and a reaction zone with an anode hydrogen flow channel, a cathode air flow channel and a cooling air flow channel in the middle of the two sides; the right end of the anode hydrogen flow channel is connected to the hydrogen outlet, and the left end is connected to the hydrogen inlet; the left end of the cathode air flow channel is connected to the air inlet, and the right end is connected to the air outlet. On the left side of the cathode closed structure of the air-cooled fuel cell, the air inlet is located below the hydrogen inlet, and on the right side of the cathode closed structure of the air-cooled fuel cell, the hydrogen outlet is located below the air outlet. The cooling air inlet of the cooling air flow channel is located below, and the cooling air outlet is located above.

[0058] At this time, the air inlet of the cathode air flow channel and the hydrogen outlet of the anode hydrogen flow channel are close to the cooling air inlet of the relatively cold cooling air flow channel. The air outlet of the cathode air flow channel and the hydrogen inlet of the anode hydrogen flow channel are close to the cooling air outlet of the relatively hot cooling air flow channel.

[0059] The test shows that the fuel cell has the same effect, and the mechanism determines that the cathode air flow contains more nitrogen, and the flow rate is at least several times that of the anode hydrogen flow, so the flow direction of the cathode air flow is decisive for the water balance distribution, and the flow direction of the anode hydrogen flow is not decisive.

[0060] The above-mentioned air-cooled fuel cell cathode closed structure is applied to the fuel cell, and the inlet and outlet of the cooling air flow and the inlet and outlet of the cathode air flow are realized by the fan.

[0061] A fuel cell system comprising an air-cooled fuel cell cathode closed structure, as shown in Figures 11 and 12, the fan is set as follows:

[0062] (1) Including a heat dissipation fan, the airflow direction is consistent with the flow direction of the fuel cell heat dissipation air flow.

[0063] (2) Including a cathode fan, the airflow direction is consistent with the flow direction of the fuel cell cathode air flow.

[0064] The combination of the above-mentioned heat dissipation fan and cathode fan makes the flow direction of the cathode air in the middle flow channel area of the fuel cell system approximately the same as the flow direction of the heat dissipation air inside the fuel cell.

[0065] Preferably, the heat dissipation fan adopts an axial flow fan, which is located downstream of the fuel cell heat dissipation air flow and pulls air from the heat dissipation flow channel of the fuel cell. Because the blade shape of the axial flow fan is usually a curved surface optimized by fluid mechanics, only one flow direction is high efficiency, so the airflow direction can be determined even in static state.

[0066] Preferably, the cathode fan adopts a centrifugal fan, which is located upstream of the fuel cell cathode air flow and blows air into the cathode flow channel of the fuel cell. Because the centrifugal fan takes in air in the center area and discharges air in the peripheral area, the airflow direction can be determined even in static state.

[0067] As mentioned above, the anode hydrogen flow, the cathode air flow and the heat dissipation air flow are parallel or even in the same direction, further, parallel and in the same direction can achieve better effect, and parallel and reverse can also be achieved according to the actual situation. It can be seen that there are two possibilities for the flow direction of hydrogen, and the system components of the fuel cell are not described in detail with reference to the prior art.

[0068] Embodiment:

[0069] In order to save research and development funds and reduce trial and error risks, a cathode closed air-cooled fuel cell with an active area of only 4*7=28 square centimeters is trial-produced, which is intended to be stacked to form a small stack of hundreds of watts to one kilowatt power, and the overall layout of the single cell is shown in Figures 4, 5 and 6.

[0070] To reduce the flow resistance, the groove depth of the horizontal flow channel (distribution zone and reaction zone) in the cathode layout is 0.65 mm; while the groove depth of the vertical flow channel (pure reaction zone) is only 0.2 mm to achieve better distribution uniformity.

[0071] As shown in Figs. 13 and 14, the planar views of the single-cell cathode plate and anode plate are shown, wherein Fig. 13 is a bottom view of the cathode plate and Fig. 14 is a top view of the anode plate. A 16-piece short stack was then made and the performance of the two connection modes was tested respectively using a low-power fuel cell test station, one of which was that the flow direction of the anode hydrogen middle flow channel zone was the same as that of the cooling air flow, and the other was that the flow direction of the anode hydrogen middle flow channel zone was opposite to that of the cooling air flow. No matter which connection mode, the flow direction of the cathode air middle flow channel zone was the same as that of the cooling air flow.

[0072] Due to the low design flow resistance, the cathode air stoichiometric ratio was attempted to be increased to 4.0, which was significantly greater than the stoichiometric ratio 2.0 of the conventional scheme. Thus, a current density of 1.4-1.5 A / cm 2 was obtained at a rated average single-cell voltage of 0.65 V, which was not only superior to 1.0 A / cm 2 of the background technology of the cathode closed air-cooled fuel cell with poor water-heat balance layout, but also superior to 1.2 A / cm 2 of the background technology of the liquid-cooled fuel cell with good water-heat balance layout.

[0073] It is worth mentioning that the preferred sub-embodiment originally predicted by the inventor was that the flow direction of the anode hydrogen middle flow channel zone was the same as that of the cooling air flow; however, the experimental data showed that the reverse was better. The inventor preliminarily analyzed that it might be because the supplier who could provide the membrane electrode with better water retention was unable to supply due to some reasons, and the membrane electrode with poor water retention was purchased from other suppliers, so that the membrane electrode in the upstream area of the cathode air flow was too dry, and the membrane electrode in the downstream area of the cathode air flow was too wet, so that the anode hydrogen reverse flow humidification was needed on the whole; and if the membrane electrode with better water retention was purchased, the result might be different. This does not affect the creativity and practicality of the specific technical features of the present application.

[0074] Table 1 below is the experimental data of the flow direction of the anode hydrogen middle flow channel zone being the same as that of the cooling air flow.

[0075] Table 1

[0076] Table 2 below is the experimental data of the flow direction of the anode hydrogen middle flow channel zone being opposite to that of the cooling air flow.

[0077] Table 2

[0078] The air-cooled fuel cell's cathode closed structure optimizes the water-heat balance layout, eliminates the wet and dry heat areas, improves the utilization efficiency of catalyst and proton exchange membrane, and improves the current density.

Claims

1. A cathode closed structure for an air-cooled fuel cell, characterized in that: It includes an air inlet and a hydrogen inlet / outlet on the left, a hydrogen inlet / outlet and an air outlet on the right, and a reaction zone with an anode hydrogen flow channel, a cathode air flow channel and a heat dissipation air flow channel in the middle of both sides. The reaction zone includes a hydrogen reaction zone and an air reaction zone; The hydrogen reaction zone includes a hydrogen inlet flow channel zone, a hydrogen middle flow channel zone and a hydrogen outlet flow channel zone, wherein the anode hydrogen flow channel of the hydrogen inlet flow channel zone and the anode hydrogen flow channel of the hydrogen outlet flow channel zone are arranged in parallel, and the anode hydrogen flow channel of the hydrogen middle flow channel zone is perpendicular to the anode hydrogen flow channels of the hydrogen inlet flow channel zone and the hydrogen outlet flow channel zone; The air reaction zone includes an air inlet flow channel zone, an air middle flow channel zone and an air outlet flow channel zone, wherein the cathode air flow channel of the air inlet flow channel zone and the cathode air flow channel of the air outlet flow channel zone are arranged in parallel, and the cathode air flow channel of the air middle flow channel zone is perpendicular to the cathode air flow channels of the air inlet flow channel zone and the air outlet flow channel zone; The air inlet of the cathode air flow channel is close to the heat dissipation air inlet of the heat dissipation air flow channel; the air outlet of the cathode air flow channel is close to the heat dissipation air outlet of the heat dissipation air flow channel.

2. The cathode closed structure of the air-cooled fuel cell according to claim 1, characterized in that: The area of ​​the hydrogen middle flow channel zone is larger than 50% of the hydrogen reaction zone.

3. The cathode closed structure of the air-cooled fuel cell according to claim 1, characterized in that: The area of ​​the middle air flow channel zone is larger than 50% of the air reaction zone.

4. The cathode closed structure of the air-cooled fuel cell according to claim 1, characterized in that: When the air inlet and hydrogen outlet are arranged on the left side of the cathode closed structure of the air-cooled fuel cell and the hydrogen inlet and air outlet are arranged on the right side, the hydrogen inlet of the anode hydrogen flow channel is close to the heat dissipation air inlet of the heat dissipation air flow channel; the hydrogen outlet of the anode hydrogen flow channel is close to the heat dissipation air outlet of the heat dissipation air flow channel; When the air inlet and hydrogen inlet are arranged on the left side of the cathode closed structure of the air-cooled fuel cell, and the hydrogen outlet and air outlet are arranged on the right side, the hydrogen inlet of the anode hydrogen flow channel is close to the heat dissipation air outlet of the heat dissipation air flow channel; The hydrogen outlet of the anode hydrogen flow channel is close to the heat dissipation air inlet of the heat dissipation air flow channel.

5. The cathode closed structure of the air-cooled fuel cell according to claim 1, characterized in that: The anode hydrogen flow channel in the hydrogen middle flow channel area is parallel to the heat dissipation air flow channel, and the cathode air flow channel in the air middle flow channel area is parallel to the heat dissipation air flow channel.

6. The cathode closed structure of the air-cooled fuel cell according to claim 1, characterized in that: The first dividing line between the hydrogen inlet flow channel area and the hydrogen middle flow channel area is arranged obliquely from top to bottom, and the second dividing line between the hydrogen outlet flow channel area and the hydrogen middle flow channel area is parallel to the first dividing line. The first dividing line and the second dividing line are at a height close to the air outlet, which is higher than a height close to the air inlet.

7. The cathode closed structure of the air-cooled fuel cell according to claim 1, characterized in that: The third dividing line between the air inlet flow channel area and the air middle flow channel area is arranged obliquely from top to bottom, and the fourth dividing line between the air outlet flow channel area and the air middle flow channel area is parallel to the third dividing line. The height of the third dividing line and the fourth dividing line close to the hydrogen outlet is higher than the height of the position close to the hydrogen inlet.

8. A fuel cell system, characterized in that: The cathode closed structure of the air-cooled fuel cell according to any one of claims 1 to 7 is adopted, and a fan is provided on the outside of the cathode closed structure of the air-cooled fuel cell.

9. The fuel cell system according to claim 8, wherein: It includes a heat dissipation fan, the airflow direction of which is consistent with the heat dissipation airflow of the fuel cell; and a cathode fan, the airflow direction of which is consistent with the cathode airflow of the fuel cell.

10. The fuel cell system according to claim 9, wherein: The heat dissipation fan is an axial flow fan, and the cathode fan is a centrifugal fan.

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