Air-cooled fuel cell waste heat recovery system

Abstract

The present invention discloses an air-cooled fuel cell waste heat recovery system, comprising a fuel cell stack, an air path system and a heat-using end component, wherein the air path system comprises a fan, a six-way valve, a three-way valve 1, a three-way valve 2 and a heat exchanger. The cathode inlet of the fuel cell stack is connected to the main air intake path, and the main air intake path is connected to the air intake branch in parallel. The cathode outlet of the fuel cell stack is connected to the main air outlet path, and the main air outlet path is connected to the air outlet branch in parallel. Compared with the prior art, the air-cooled fuel cell waste heat recovery system of the present invention adopts corresponding control of the six-way valve to change the flow path of the air path airflow without changing the original structure of the fuel cell system, thereby achieving low load and starting condition control of high potential, improving the durability of the fuel cell, recovering waste heat, and improving energy utilization.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to an air-cooled fuel cell waste heat recovery system. Background Art

[0002] As human activities increase the demand for energy, energy depletion and environmental pollution become increasingly serious. As one of the new energy sources, hydrogen is extremely environmentally friendly and has multiple advantages such as high calorific value, low production cost, and zero carbon emissions. It has broad application prospects in transportation, industry, electricity and other fields. Fuel cells, as an efficient and environmentally friendly energy conversion device, have received widespread attention and rapid development. Fuel cells are devices that directly convert the chemical energy of fuel into electrical energy. Because they are not restricted by the Carnot cycle, they have high energy conversion efficiency, are clean and environmentally friendly, have a simple structure, and produce low noise. They have been widely used in transportation, distributed power generation, portable electronic devices and other fields. During the actual operation of fuel cells, in addition to outputting electrical energy, a large amount of waste heat is also generated. If this waste heat can be effectively recovered, it can not only improve energy utilization, but also further reduce operating costs and environmental impact.

[0003] Currently, research on fuel cell waste heat recovery primarily focuses on water-cooled fuel cell systems. These systems utilize circulating cooling water to remove waste heat generated by the fuel cell and reuse it for secondary uses such as heating and power generation. However, since water-cooling systems require auxiliary equipment such as water pumps and cooling lines, they increase system complexity and maintenance costs. Furthermore, water-cooling systems are limited in applications requiring lightweight and highly portable systems.

[0004] Air-cooled fuel cells, due to their simple structure, easy maintenance, and strong adaptability, have broad application prospects in portable power supplies, drones, electric bicycles, and other fields. Current research on air-cooled fuel cells focuses on improving cooling and heat dissipation efficiency. Waste heat recovery technology is still immature, and secondary utilization of waste heat is limited. Summary of the Invention

[0005] The purpose of the present invention is to provide an air-cooled fuel cell waste heat recovery system to solve the problems existing in the above-mentioned prior art, improve the durability of the fuel cell, recover waste heat, and improve energy utilization.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides an air-cooled fuel cell waste heat recovery system, comprising a fuel cell stack, an air path system and a heat-using end component, wherein the air path system comprises a fan, a six-way valve, a three-way valve 1, a three-way valve 2 and a heat exchanger;

[0008] The cathode inlet of the stack is connected to the main air inlet path, and the main air inlet path is connected in parallel with the air inlet branch path; the cathode outlet of the stack is connected to the main air outlet path, and the main air outlet path is connected in parallel with the air outlet branch path;

[0009] On the main air intake path, the fan, port 1 of the six-way valve, port 2 of the six-way valve, port 1 of the three-way valve, port 2 of the three-way valve, and the cathode inlet of the fuel cell stack are connected in sequence;

[0010] On the air inlet branch, port 2 of the six-way valve, port 3 of the six-way valve, the cold side inlet of the heat exchanger, the cold side outlet of the heat exchanger, and port 3 of the three-way valve are connected in sequence;

[0011] On the main gas outlet path, the cathode outlet of the stack, port 1 of the second three-way valve, port 2 of the second three-way valve, port 5 of the six-way valve, port 6 of the six-way valve, and the hot end assembly are connected in sequence;

[0012] On the gas outlet branch, port 5 of the six-way valve, port 4 of the six-way valve, the hot side inlet of the heat exchanger, the hot side outlet of the heat exchanger, and port 3 of the second three-way valve are connected in sequence.

[0013] Preferably, the air-cooled fuel cell waste heat recovery system also includes a first temperature sensor, a second temperature sensor and a controller, the first temperature sensor is used to monitor the outside air temperature T0, and the second temperature sensor is used to monitor the gas inlet temperature T3 at the cathode inlet of the fuel cell stack; the first temperature sensor is electrically connected to the controller for transmitting the monitoring results to the controller; the controller is electrically connected to the six-way valve for controlling the connection mode of the six-way valve to control the air path system.

[0014] Preferably, the control mode of the controller is as follows:

[0015] Comparing the monitoring result T0 of the first temperature sensor with the target set temperature T1 preset in the controller;

[0016] If T0≤T1, then execute steps S10, S20, and S30 in sequence;

[0017] If T0>T1, determine whether the fuel cell in the stack is in a low-load, startup state; if the determination result is yes, execute steps S40 and S60 in sequence; if the determination result is no, execute steps S50 and S60 in sequence; wherein:

[0018] S10, connecting port 1 to port 3 of the six-way valve, connecting port 5 to port 4 of the six-way valve, and connecting port 5 to port 6 of the six-way valve;

[0019] S20, adjusting the valve opening between ports 5 and 4 of the six-way valve so that the monitoring result T3 of the second temperature sensor gradually approaches the target stack entry temperature T2 preset in the controller;

[0020] S30, turning on the hot end assembly;

[0021] S40, connecting port 1 to port 2 of the six-way valve, connecting port 5 to port 3 of the six-way valve, and connecting port 5 to port 6 of the six-way valve;

[0022] S50, connecting ports 1 and 2 of the six-way valve, and connecting ports 5 and 6 of the six-way valve;

[0023] S60, closing the hot end assembly.

[0024] Compared with the prior art, the present invention has achieved the following technical effects:

[0025] The air-cooled fuel cell waste heat recovery system of this invention utilizes a six-way valve and heat exchanger, resulting in a compact structure that simplifies system design, reduces weight, and reduces maintenance costs. High voltage limiting control is implemented during low-load and startup conditions, improving system durability. While enhancing fuel cell stack performance, it also enables secondary utilization of waste heat. By delivering high-temperature gas to heat-using components, the system's overall energy efficiency, cost-effectiveness, and sustainability are enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 Schematic diagram of an air-cooled fuel cell waste heat recovery system according to an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of the controller's control method;

[0029] In the figure: 1-air flow; 2-fan; 3-six-way valve; 4-three-way valve one; 5-cell stack; 6-three-way valve two; 7-heat exchanger; 8-hot end assembly. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] The purpose of the present invention is to provide an air-cooled fuel cell waste heat recovery system to improve the durability of the fuel cell and recover waste heat, thereby improving energy utilization.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Reference Figure 1 、 Figure 2 This embodiment provides an air-cooled fuel cell waste heat recovery system, including a fuel cell stack 5, an air path system and a hot end component 8. The air path system includes a fan 2, a six-way valve 3, a three-way valve 1 4, a three-way valve 2 6 and a heat exchanger 7.

[0034] The cathode inlet of the stack 5 is connected to the main air inlet path, and the main air inlet path is connected in parallel with the air inlet branch path. The cathode outlet of the stack 5 is connected to the main air outlet path, and the main air outlet path is connected in parallel with the air outlet branch path.

[0035] On the main air intake path, the fan 2, port 1 of the six-way valve 3, port 2 of the six-way valve 3, port 1 of the three-way valve 4, port 2 of the three-way valve 4, and the cathode inlet of the fuel cell stack 5 are connected in sequence.

[0036] On the air intake branch, port 2 of the six-way valve 3, port 3 of the six-way valve 3, the cold side inlet of the heat exchanger 7, the cold side outlet of the heat exchanger 7, and port 3 of the three-way valve 4 are connected in sequence.

[0037] On the main gas outlet path, the cathode outlet of the fuel cell stack 5, port 1 of the three-way valve 2 6, port 2 of the three-way valve 2 6, port 5 of the six-way valve 3, and port 6 of the six-way valve 3 are connected in sequence with the hot end assembly 8.

[0038] On the gas outlet branch, port 5 of the six-way valve 3, port 4 of the six-way valve 3, the hot side inlet of the heat exchanger 7, the hot side outlet of the heat exchanger 7, and port 3 of the three-way valve 2 6 are connected in sequence.

[0039] The term "connected in sequence" as mentioned above refers to connecting in sequence through pipelines in the order described, so that the gas flows through each structure in sequence on the corresponding branch.

[0040] The working principle of the air-cooled fuel cell waste heat recovery system in this embodiment is as follows:

[0041] This embodiment adjusts the layout of the air path system by controlling the openings and closings of the six-way valve 3, thereby changing the airflow direction according to actual needs. Heat from the airflow exiting the cathode outlet of the stack 5 is used to preheat the airflow entering the cathode inlet of the stack 5 or to supply heat to the hot end assembly 8, thereby recovering waste heat. This control process can be manually or automatically controlled.

[0042] As a possible example, in this embodiment, to improve the system's automation level, the air-cooled fuel cell waste heat recovery system further includes a first temperature sensor, a second temperature sensor, and a controller. The first temperature sensor is used to monitor the ambient air temperature T0, and the second temperature sensor is used to monitor the gas inlet temperature T3 at the cathode inlet of the fuel cell stack 5. The first temperature sensor is electrically connected to the controller for transmitting the monitoring results to the controller. The controller is electrically connected to the six-way valve 3 for controlling the communication mode of the six-way valve 3 to control the air path system.

[0043] Exemplarily, the control mode of the controller is as follows:

[0044] The monitoring result T0 of the first temperature sensor is compared with the target set temperature T1 preset in the controller.

[0045] If T0≤T1 (i.e., waste heat recovery is required), steps S10, S20, and S30 are performed in sequence. The high-temperature gas at the cathode outlet of the fuel cell stack 5 is used through the heat exchanger 7 to heat the low-temperature air at the cathode inlet of the fuel cell stack 5, thereby increasing the temperature of the gas entering the fuel cell stack 5 to maintain the fuel cell at a suitable operating temperature and improve the performance of the fuel cell stack 5. The high-temperature gas after passing through the heat exchanger 7 is further mixed with the gas at the cathode outlet of the fuel cell stack 5 and transported to the hot end assembly 8 to continue waste heat recovery, thereby improving energy utilization.

[0046] If T0>T1 (ie, waste heat recovery is not required), it is determined whether the fuel cell where the stack 5 is located is in a low-load, startup state.

[0047] If the judgment result is yes, steps S40 and S60 are executed in sequence to send the high-humidity, low-oxygen concentration gas at the cathode outlet of the fuel cell stack 5 back to the cathode inlet of the fuel cell stack 5 and mix it with fresh air from the fan to achieve the effect of limiting high potential and increasing humidity, thereby improving the durability of the fuel cell.

[0048] If the judgment result is no, steps S50 and S60 are executed in sequence.

[0049] The operation contents of each step are as follows:

[0050] S10. Connect ports 1 and 3 of the six-way valve 3, connect ports 5 and 4 of the six-way valve 3, and connect ports 5 and 6 of the six-way valve 3. At this point, the parallel inlet and outlet branches are enabled, and the heat exchanger 7 operates, using the heat of the airflow flowing out of the cathode outlet of the fuel cell stack 5 to preheat the airflow flowing into the cathode inlet of the fuel cell stack 5.

[0051] S20: Adjust the valve opening between ports 5 and 4 of six-way valve 3 so that the second temperature sensor's monitoring result T3 gradually approaches the target stack entry temperature T2 preset in the controller. This adjustment step is intended to improve heat exchange efficiency, ensuring that the second temperature sensor's monitoring result T3 reaches the target stack entry temperature T2 as quickly as possible.

[0052] S30: Start the hot-end assembly 8. If the heat of the airflow flowing out of the cathode outlet of the fuel cell stack 5 is sufficient to raise the second temperature sensor's monitoring result T3 to a certain range near the target stack entry temperature T2, this step is used to supply the waste heat to the hot-end assembly 8 for further utilization. It should be noted that step S20 precedes step S30, meaning that the fuel cell's stack entry temperature and stack power generation efficiency must be ensured before considering waste heat output.

[0053] S40: Connect ports 1 and 2 of the six-way valve 3, connect ports 5 and 3 of the six-way valve 3, and connect ports 5 and 6 of the six-way valve 3. This step directs the airflow from the cathode outlet of the fuel cell stack 5 directly to the intake branch through the six-way valve 3, and returns the high-humidity, low-oxygen-concentration gas at the cathode outlet of the fuel cell stack 5 to the cathode inlet of the fuel cell stack 5, where it is mixed with fresh air from the fan. This limits high potential and increases humidity, thereby improving the durability of the fuel cell.

[0054] S50: Connect ports 1 and 2 of the six-way valve 3, and connect ports 5 and 6 of the six-way valve 3. This step directly directs the airflow from the cathode outlet of the stack 5 to the hot end assembly 8, without using waste heat to increase the airflow temperature at the cathode inlet of the stack 5.

[0055] S60, closing the hot end assembly 8.

[0056] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An air-cooled fuel cell waste heat recovery system, characterized by: It includes a fuel cell stack, an air path system, a hot end component, a first temperature sensor, a second temperature sensor and a controller. The air path system includes a fan, a six-way valve, a three-way valve 1, a three-way valve 2 and a heat exchanger. The cathode inlet of the stack is connected to the main air inlet path, and the main air inlet path is connected in parallel with the air inlet branch path; the cathode outlet of the stack is connected to the main air outlet path, and the main air outlet path is connected in parallel with the air outlet branch path; On the main air intake path, the fan, port 1 of the six-way valve, port 2 of the six-way valve, port 1 of the three-way valve, port 2 of the three-way valve, and the cathode inlet of the fuel cell stack are connected in sequence; On the air inlet branch, port 2 of the six-way valve, port 3 of the six-way valve, the cold side inlet of the heat exchanger, the cold side outlet of the heat exchanger, and port 3 of the three-way valve are connected in sequence; On the main gas outlet path, the cathode outlet of the stack, port 1 of the second three-way valve, port 2 of the second three-way valve, port 5 of the six-way valve, port 6 of the six-way valve, and the hot end assembly are connected in sequence; On the gas outlet branch, port 5 of the six-way valve, port 4 of the six-way valve, the hot side inlet of the heat exchanger, the hot side outlet of the heat exchanger, and port 3 of the second three-way valve are connected in sequence; The control mode of the controller is as follows: Comparing the outside air temperature T0 monitored by the first temperature sensor with the target set temperature T1 preset in the controller; If T0≤T1, then execute steps S10, S20, and S30 in sequence; If T0>T1, determine whether the fuel cell in the stack is in a low-load, startup state; if the determination result is yes, execute steps S40 and S60 in sequence; if the determination result is no, execute steps S50 and S60 in sequence; wherein: S10, connecting port 1 to port 3 of the six-way valve, connecting port 5 to port 4 of the six-way valve, and connecting port 5 to port 6 of the six-way valve; S20, adjusting the valve opening between ports 5 and 4 of the six-way valve so that the gas inlet temperature T3 monitored by the second temperature sensor gradually approaches the target inlet temperature T2 preset in the controller; S30, turning on the hot end assembly; S40, connecting port 1 to port 2 of the six-way valve, connecting port 5 to port 3 of the six-way valve, and connecting port 5 to port 6 of the six-way valve; S50, connecting ports 1 and 2 of the six-way valve, and connecting ports 5 and 6 of the six-way valve; S60, closing the hot end assembly.

2. The air-cooled fuel cell waste heat recovery system according to claim 1, characterized in that: The first temperature sensor is used to monitor the external air temperature T0, and the second temperature sensor is used to monitor the gas inlet temperature T3 at the cathode inlet of the fuel cell stack; the first temperature sensor is electrically connected to the controller for transmitting the monitoring results to the controller; the controller is electrically connected to the six-way valve for controlling the connection mode of the six-way valve to control the air path system.

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