A two-stage composite auxiliary cold start device for air-cooled fuel cells using honeycomb ceramic tubes

Abstract

This invention belongs to the technical field of proton exchange membrane fuel cells and discloses a two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell. The device includes an air supply fan, a primary heater, a secondary heater, and multiple solenoid valves. The air supply fan is located near the cathode of the cathode-cooled fuel cell to provide intake air to the primary heater. The primary heater is in the form of a resistance wire and is used to perform primary heating of the intake air. The secondary heater is in the form of a honeycomb ceramic hydrogen-oxygen catalytic heater and works in conjunction with the primary heater to perform secondary heating of the air. Furthermore, the multiple solenoid valves are used to perform different control combinations on the hydrogen supplied to the fuel cell stack and / or the secondary heater, thereby achieving operation under different conditions. This invention enables low-cost, non-destructive, cryogenic cold start and operation of open cathode fuel cell stacks, while also possessing advantages such as compact structure, ease of operation, and good adaptability.

Description

Technical Field

[0001] This invention belongs to the technical field of proton exchange membrane fuel cells, and more specifically, relates to a two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell. Background Technology

[0002] Currently, open-cathode proton exchange membrane fuel cells (PEMFCs) typically consist of several individual cells connected in series to form a stack. Each individual cell is composed of bipolar plates, membrane electrode assemblies (MEAs), and bipolar plates. Due to its open-cathode structure, a fan is installed before the cathode inlet or outlet to blow or draw air into the stack's cathode channels, thus supplying air and dissipating heat to the cathode. However, in low-temperature environments, the large amount of cold air introduced by the fan can cause the stack temperature to drop too low. This can lead to the liquefaction of water produced during the reaction, blocking the gas channels, and even causing irreversible and severe damage to the MEAs due to solid ice condensing on the cathode catalyst layer, ultimately resulting in low-temperature start-up failure.

[0003] To address the above technical problems, some solutions have been proposed in the prior art. For example, CN201480012775.9 discloses a fuel cell system for use as a power source on an aircraft, utilizing a catalytic system. The catalytic system receives and burns hydrogen from the fuel cell assembly or hydrogen storage device to provide heat for heating water and regulating the internal operating temperature of the fuel cell. However, this type of catalytic burner requires adjusting the temperature of the liquid cooling circuit of the liquid-cooled fuel cell to achieve the purpose of regulating the cell temperature. Its system structure is complex and requires the use of multiple heat exchangers in combination.

[0004] CN201911117794.9 discloses a barrel-type catalytic burner that utilizes the exothermic reaction of hydrogen-oxygen catalytic combustion. It is suitable for methanol-water vapor reforming to produce hydrogen in high-temperature proton exchange membrane fuel cells, providing heat to the reforming reactor. However, further research shows that this scheme directly uses the exothermic reaction of hydrogen catalytic combustion to provide heat to the reforming reactor, and is only suitable for regulating the bed temperature of the reforming reactor. Furthermore, CN202110887306.3 discloses a device for improving the low-temperature adaptability of air-cooled fuel cell stacks. This device recycles the heat released by the fuel cell itself during operation by guiding the air from the cathode outlet back to the cathode inlet, achieving auxiliary air intake heating for air-cooled fuel cells in low-temperature environments. However, this device has significant limitations in extremely low-temperature environments. During the initial startup phase, the stack fails to provide heat, and the device can only maintain stable operation in general low-temperature environments, failing to achieve a cold-start effect.

[0005] Accordingly, further research and improvements are urgently needed in this field to better meet the complex requirements of low-cost, non-destructive cryogenic cold start-up and operation of open cathode fuel cell stacks. Summary of the Invention

[0006] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a two-stage composite auxiliary cold start device for honeycomb ceramic tube air-cooled fuel cells. By closely integrating the specific requirements for low-cost, non-destructive ultra-low temperature cold start and operation of open cathode fuel cell stacks, a two-stage heating system of resistance wire heating and ceramic honeycomb catalytic heating is introduced. At the same time, the specific structure of related components and various heating methods have been redesigned, thereby enabling low-cost, non-destructive ultra-low temperature cold start and operation of open cathode fuel cell stacks. It also has the advantages of compact structure, easy operation, and good adaptability.

[0007] To achieve the above objectives, according to the present invention, a two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell is provided, characterized in that the device includes an air supply fan (1), a primary heater (2), a secondary heater (3), and multiple solenoid valves, wherein:

[0008] The air supply fan (1) is located near the cathode of the cathode-cooled fuel cell and is used to supply intake air to the primary heater (2); the primary heater (2) is in the form of a resistance wire and is used to perform primary heating on the intake air supplied thereto; the secondary heater (3) is in the form of a honeycomb ceramic hydrogen-oxygen catalytic heater and is used to perform controllable secondary heating on the air flowing through the primary heater (2);

[0009] The plurality of solenoid valves include a first to a fourth solenoid valve, wherein the first solenoid valve (10) is installed upstream of the hydrogen inlet (5) of the fuel cell stack body (4) and is used to connect / disconnect the hydrogen supplied from an external hydrogen source to the fuel cell stack body (4); the second solenoid valve (9) is installed in the hydrogen pipeline (11) between the external hydrogen source and the secondary heater (3) and is used to connect / disconnect the hydrogen supplied from the external hydrogen source to the interior of the secondary heater (3); the third solenoid valve (8) is installed between the hydrogen outlet (6) of the fuel cell stack body (4) and the hydrogen pipeline (11) and is used to connect / disconnect the hydrogen discharged from the anode of the cathode air-cooled fuel cell to the secondary heater (3); and the fourth solenoid valve (7) is installed downstream of the third solenoid valve (8) and is used to connect / disconnect the hydrogen discharged from the hydrogen outlet (6) to the external environment.

[0010] Based on the above design, a two-stage heating system combining resistance wire heating and ceramic honeycomb catalytic heating is employed. Multiple solenoid valves are used to control various combinations of operating conditions. In this way, firstly, cold air in a low-temperature environment, after being heated by the first set of resistance wires, can be further heated by the second set of catalyst-coated honeycomb ceramic heating tubes, reaching a temperature of approximately 50°C before entering the fuel cell stack. Secondly, during the initial startup phase, the resistance wires can be powered by an external circuit, allowing the cold air to enter the stack after being heated by the resistance wires. Once the proton exchange membrane fuel cell stack starts up, the resistance wires switch to powering the stack. The lower part of the honeycomb ceramic tubes is connected to the stack's hydrogen outlet via pipelines. When the stack operates in closed mode, the hydrogen outlet uses pulses to introduce hydrogen from the stack into the honeycomb ceramic tubes. The hydrogen reacts with oxygen in the air within the honeycomb ceramic tubes, generating heat that further heats the air passing through the resistance wires. This allows the cold air to be heated to 30-60°C through both the resistance wires and the honeycomb ceramic tubes before entering the stack, thus achieving lossless startup and stable operation of the stack in ultra-low temperature environments.

[0011] As a further preferred embodiment, for the primary heater (2), its resistance wires are preferably arranged in a cross pattern, and the number of wires is designed to be 5 to 30 groups, the heating power is set to 1kW to 3kW, and the arrangement interval is 3cm to 10cm.

[0012] As a further preferred embodiment, the secondary heater (3) preferably includes a hydrogen distribution unit (3_1) and a honeycomb ceramic catalyst (3_2), wherein the bottom of the hydrogen distribution unit (3_1) is used to introduce incoming hydrogen, and its two sides adopt a porous mesh structure, thereby allowing the air blown in by the air supply fan (1) and the incoming hydrogen to be evenly distributed and enter the honeycomb ceramic catalyst (3_2); the honeycomb ceramic catalyst (3_2) is provided with a plurality of honeycomb tubular vent holes, and a catalyst is coated on the vent walls of these honeycomb tubular vent holes.

[0013] As a further preferred embodiment, for the honeycomb ceramic catalyst (3_2) of the secondary heater (3), its carrier structure pore density is preferably designed to be 400 pores / square inch to 700 pores / square inch, and more preferably 600 pores / square inch.

[0014] As a further preferred embodiment, the above-mentioned device operates under one of the following conditions:

[0015] In the first operating condition, when the ambient temperature T is between -40℃ and -20℃, the fuel cell stack body (4) is preheated to 5℃ to 10℃. The second solenoid valve (9) and the first solenoid valve (10) are opened to simultaneously introduce hydrogen into the fuel cell stack body (4) and the secondary heater (3), while the third solenoid valve (8) and the fourth solenoid valve (7) at the outlet are kept closed. At this time, the fuel cell stack relies on the primary heater (2) and the secondary heater (3) to heat the cathode air in two stages. Then, the fuel cell stack body (4) keeps the anode closed and the power supply of the primary heater (2) is switched to the power supply of the fuel cell stack to heat the incoming air.

[0016] When the fuel cell is set to the timed anode pulse mode, the third solenoid valve (8) is opened to perform anode pulse. The hydrogen gas discharged by the third solenoid valve (8) merges into the incoming hydrogen gas from the second solenoid valve (9) and then enters the interior of the secondary heater (3) for secondary heating of the incoming air.

[0017] As a further preferred embodiment, the above-mentioned device operates under one of the following conditions:

[0018] In the second operating condition, when the ambient temperature T is between -20℃ and -10℃, the fuel cell stack (4) is preheated to 5℃ to 10℃. The first solenoid valve (10) is opened and the second solenoid valve (9) is closed. Hydrogen gas is only introduced into the fuel cell stack (4), while the third solenoid valve (8) and the fourth solenoid valve (7) are kept closed. At this time, the fuel cell stack (4) relies solely on the primary heater (2) to heat the cathode to allow air to flow. Then, the fuel cell stack (4) operates with the anode closed, and the power supply of the primary heater (2) is switched to the power supply of the fuel cell stack.

[0019] When the fuel cell stack is set to timed anode pulse mode, the third solenoid valve (8) is opened to allow hydrogen gas discharged from the fuel cell stack to enter the secondary heater (3) for intermittent secondary heating of incoming air.

[0020] As a further preferred embodiment, the above-mentioned device operates under one of the following conditions:

[0021] In the third operating condition, when the ambient temperature T is between -10℃ and T < 0℃, the power supply of the first-stage heater (2) can be turned off, and hydrogen gas from the anode of the fuel cell stack can be used to intermittently heat the fuel cell stack body (4) in the second-stage heater (3) to supply air.

[0022] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0023] 1. This invention improves and redesigns the overall composition of the two-stage composite auxiliary cold start device, with the resistance wire and honeycomb ceramic tube being heated in stages, which can fully heat the air temperature at the cathode inlet of the open cathode stack.

[0024] 2. In particular, the present invention can flexibly select three heating methods: resistance wire heating, honeycomb ceramic tube hydrogen-oxygen catalytic heating, and a combination of resistance wire heating and honeycomb ceramic tube hydrogen-oxygen catalytic heating. The heating strategy can be reasonably adjusted according to different low-temperature environments and operating conditions.

[0025] 3. Because the hydrogen-oxygen catalytic reaction occurs inside the honeycomb ceramic tube, the air that is secondarily heated into the fuel cell stack does not cause damage to the fuel cell stack, allowing the fuel cell stack to operate stably and without damage in an ultra-low temperature environment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell according to the present invention.

[0027] Figure 2 This is a preferred embodiment of the present invention, used to specifically show a schematic diagram of the internal structure of a two-stage heater, wherein a partial structure is further enlarged for display;

[0028] In all the accompanying drawings, the same reference numerals denote the same elements or structures, wherein:

[0029] 1-Gas supply fan; 2-First stage heater; 3-Second stage heater; 4-Stack body; 5-Hydrogen inlet; 6-Hydrogen outlet; 7-Fourth solenoid valve; 8-Third solenoid valve; 9-Second solenoid valve; 10-First solenoid valve; 11-Hydrogen pipeline; 3_1-Hydrogen distribution unit; 3_2-Honeycomb ceramic catalyst. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Figure 1 This is a schematic diagram of the overall structure of the two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell according to the present invention. Figure 1 As shown, the device mainly includes an air supply fan 1, a primary heater 2, a secondary heater 3, and multiple solenoid valves, namely the first solenoid valve 10, the second solenoid valve 9, the third solenoid valve 8, and the fourth solenoid valve 7. Each of these components will be explained in detail below.

[0032] The air supply fan 1 is located near the cathode of the cathode-cooled fuel cell and is used to supply intake air to the primary heater 2. The primary heater 2 is in the form of a resistance wire and is used to perform primary heating on the intake air supplied thereto. The secondary heater 3 is in the form of a honeycomb ceramic hydrogen-oxygen catalytic heater and is used to perform controllable secondary heating on the air flowing through the primary heater 2.

[0033] See Figure 1 Specifically, the plurality of solenoid valves include a first to a fourth solenoid valve. The first solenoid valve 10 is installed upstream of the hydrogen inlet 5 of the fuel cell stack body 4 and is used to connect / disconnect hydrogen supplied from an external hydrogen source to the fuel cell stack body 4. The second solenoid valve 9 is installed in the hydrogen pipeline 11 between the external hydrogen source and the secondary heater 3 and is used to connect / disconnect hydrogen supplied from the external hydrogen source to the interior of the secondary heater 3. The third solenoid valve 8 is installed between the hydrogen outlet 6 of the fuel cell stack body 4 and the hydrogen pipeline 11 and is used to connect / disconnect hydrogen discharged from the anode of the cathode air-cooled fuel cell to the secondary heater 3. The fourth solenoid valve 7 is installed downstream of the third solenoid valve 8 and is used to connect / disconnect hydrogen discharged from the hydrogen outlet 6 to the external environment.

[0034] With the above design, during startup, the intake air is heated by a resistance wire in the first stage. The first solenoid valve 10 and the fourth solenoid valve 7 are closed, while the second solenoid valve 9 and the third solenoid valve 8 are opened. Hydrogen gas is then introduced into the honeycomb ceramic heater to react with the air for secondary heating. The heated air, after being heated twice, enters the cathode channel of the fuel cell stack body 4, thus achieving the purpose of heating the fuel cell stack.

[0035] In this way, cold air is introduced into the fuel cell stack through primary heating with resistance wire, enabling non-destructive cold start of the open cathode fuel cell stack in a low-temperature environment. After startup, the intake air is reheated by a ceramic honeycomb catalytic heating device, which can effectively increase the temperature of the air entering the stack cathode, while reducing the heating power of the resistance wire, thus achieving low-cost, non-destructive ultra-low temperature cold start and operation of the open cathode fuel cell stack.

[0036] According to a preferred embodiment of the present invention, for the secondary heater 3, see... Figure 2 Preferably, it includes a hydrogen distribution unit 3_1 and a honeycomb ceramic catalyst 3_2. The bottom of the hydrogen distribution unit 3_1 is used to introduce incoming hydrogen, and its two sides adopt a porous mesh structure, thereby allowing the air blown in by the air supply fan 1 and the incoming hydrogen to be evenly distributed and enter the honeycomb ceramic catalyst 3_2. The honeycomb ceramic catalyst 3_2 is provided with a plurality of honeycomb tubular vent holes, and a catalyst is coated on the vent walls of these honeycomb tubular vent holes.

[0037] The operating principle and process of the device according to the present invention under different working conditions will be explained in detail below.

[0038] In the first operating condition, when the ambient temperature T is between -40℃ and -20℃, the fuel cell stack body 4 is preheated to 5℃ to 10℃. The second solenoid valve 9 and the first solenoid valve 10 are opened to simultaneously introduce hydrogen into the fuel cell stack body 4 and the secondary heater 3, while the third solenoid valve 8 and the fourth solenoid valve 7 at the outlet are kept closed. At this time, the fuel cell stack relies on the primary heater 2 and the secondary heater 3 to heat the cathode air in two stages. Then, the fuel cell stack body 4 keeps the anode closed, and the power supply of the primary heater 2 is switched to the fuel cell power supply to heat the air. When the fuel cell stack is set to the timed anode pulse mode, the third solenoid valve 8 is opened to perform anode pulse. The hydrogen discharged from the third solenoid valve 8 merges with the hydrogen flowing in through the second solenoid valve 9, and then enters the secondary heater 3 to reheat the air.

[0039] In the second operating condition, when the ambient temperature T is between -20℃ and -10℃, the fuel cell stack 4 is preheated to 5℃ to 10℃. The first solenoid valve 10 is opened and the second solenoid valve 9 is closed, allowing hydrogen gas to enter only the fuel cell stack 4. At the same time, the third solenoid valve 8 and the fourth solenoid valve 7 are kept closed. In this case, the fuel cell stack 4 relies solely on the primary heater 2 to heat the cathode airflow. Then, the fuel cell stack 4 operates with the anode closed, and the power supply of the primary heater 2 is switched to the fuel cell stack power supply. When the fuel cell stack is set to a timed anode pulse mode, the third solenoid valve 8 is opened to allow hydrogen gas discharged from the fuel cell stack to enter the secondary heater 3 for intermittent secondary heating of the incoming airflow.

[0040] In the third operating condition, when the ambient temperature T is between -10℃ and T < 0℃, the power supply to the first-stage heater 2 can be turned off, and hydrogen gas from the anode of the fuel cell stack can be used to intermittently heat the fuel cell stack body 4 in the second-stage heater 3 to supply air.

[0041] In summary, the two-stage composite auxiliary cold start device according to the present invention introduces a two-stage heating system of resistance wire heating + ceramic honeycomb catalytic heating, and redesigns the specific structure of related components and various heating methods. Accordingly, it can successfully achieve low-cost, non-destructive ultra-low temperature cold start and operation of open cathode fuel cell stacks, and has the advantages of compact structure, easy operation, and good adaptability.

[0042] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell, characterized in that, The device includes an air supply fan (1), a primary heater (2), a secondary heater (3), and multiple solenoid valves, wherein: The air supply fan (1) is located near the cathode of the cathode-cooled fuel cell and is used to supply intake air to the primary heater (2). The primary heater (2) is in the form of a resistance wire and is used to perform primary heating on the intake air supplied thereto. The secondary heater (3) is in the form of a honeycomb ceramic hydrogen-oxygen catalytic heater and is used to perform controllable secondary heating on the air flowing through the primary heater (2). That is, the secondary heater (3) includes a hydrogen distribution unit (3-1) and a honeycomb ceramic catalyst (3-2). The bottom of the hydrogen distribution unit (3-1) is used to introduce incoming hydrogen, and its two sides adopt a porous mesh structure, thereby allowing the air blown in by the air supply fan (1) and the incoming hydrogen to be evenly distributed and enter the honeycomb ceramic catalyst (3-2). The honeycomb ceramic catalyst (3-2) is provided with multiple honeycomb tubular vent holes, and a catalyst is coated on the walls of these honeycomb tubular vent holes. The plurality of solenoid valves include a first to a fourth solenoid valve, wherein the first solenoid valve (10) is installed upstream of the hydrogen inlet (5) of the fuel cell stack body (4) and is used to connect / disconnect the hydrogen supplied from an external hydrogen source to the fuel cell stack body (4); the second solenoid valve (9) is installed in the hydrogen pipeline (11) between the external hydrogen source and the secondary heater (3) and is used to connect / disconnect the hydrogen supplied from the external hydrogen source to the interior of the secondary heater (3); the third solenoid valve (8) is installed between the hydrogen outlet (6) of the fuel cell stack body (4) and the hydrogen pipeline (11) and is used to connect / disconnect the hydrogen discharged from the anode of the cathode air-cooled fuel cell to the secondary heater (3); and the fourth solenoid valve (7) is installed downstream of the third solenoid valve (8) and is used to connect / disconnect the hydrogen discharged from the hydrogen outlet (6) to the external environment.

2. The two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell as described in claim 1, characterized in that, For the first-stage heater (2), its resistance wires are arranged in a cross pattern, and the number of wires is designed to be 5 to 30 groups. The heating power is set to 1kW to 3kW, and the arrangement interval is 3cm to 10cm.

3. The two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell as described in claim 2, characterized in that, For the honeycomb ceramic catalyst (3-2) of the secondary heater (3), its carrier structure pore density is designed to be 400 pores / square inch to 700 pores / square inch.

4. The two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell as described in claim 3, characterized in that, For the honeycomb ceramic catalyst (3-2) of the secondary heater (3), its carrier structure pore density is designed to be 600 pores / square inch.

5. A two-stage composite auxiliary cold start device for a honeycomb ceramic tube air-cooled fuel cell as described in any one of claims 1-4, characterized in that, The above-mentioned device operates under one of the following conditions: In the first operating condition, when the ambient temperature T is between -40℃ and -20℃, the fuel cell stack body (4) is preheated to 5℃ to 10℃. The second solenoid valve (9) and the first solenoid valve (10) are opened to simultaneously introduce hydrogen into the fuel cell stack body (4) and the secondary heater (3), while the third solenoid valve (8) and the fourth solenoid valve (7) at the outlet are kept closed. At this time, the fuel cell stack relies on the primary heater (2) and the secondary heater (3) to heat the cathode air in two stages. Then, the fuel cell stack body (4) keeps the anode closed and the power supply of the primary heater (2) is switched to the power supply of the fuel cell stack to heat the incoming air. When the fuel cell is set to the timed anode pulse mode, the third solenoid valve (8) is opened to perform anode pulse. The hydrogen gas discharged by the third solenoid valve (8) merges into the incoming hydrogen gas from the second solenoid valve (9) and then enters the interior of the secondary heater (3) for secondary heating by air flow. In the second operating condition, when the ambient temperature T is between -20℃ and -10℃, the fuel cell stack (4) is preheated to 5℃ to 10℃, the first solenoid valve (10) is opened and the second solenoid valve (9) is closed, and hydrogen gas is only introduced into the fuel cell stack (4). At the same time, the third solenoid valve (8) and the fourth solenoid valve (7) are kept closed. At this time, the fuel cell stack (4) relies only on the primary heater (2) to heat the cathode to allow air to flow. Then the fuel cell stack (4) adopts closed anode operation, and the power supply of the primary heater (2) is switched to the power supply of the fuel cell stack. When the fuel cell stack is set to timed anode pulse mode, the third solenoid valve (8) is opened to allow hydrogen gas discharged from the fuel cell stack to enter the secondary heater (3) for intermittent secondary heating of incoming air. In the third operating condition, when the ambient temperature T is -10℃≤T<0℃, the power supply of the first-stage heater (2) is turned off, and hydrogen gas is used to intermittently heat the fuel cell body (4) in the second-stage heater (3) to supply air.

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