Air cooling type fuel cell waste heat recovery system

Abstract

The invention discloses an air cooling type fuel cell waste heat recovery system which comprises an electric pile, an air path system and a heat utilization end assembly, and the air path system comprises a fan, a six-way valve, a first three-way valve, a second three-way valve and a heat exchanger. A cathode inlet of the electric pile is connected with an air inlet main path; and the air inlet main path is connected with an air inlet branch in parallel. A cathode outlet of the electric pile is connected with a gas outlet main path which is connected with a gas outlet branch in parallel. Compared with the prior art, the air cooling type fuel cell waste heat recovery system has the advantages that the six-way valve is correspondingly controlled, so that on the basis of not changing the original structure of a fuel cell system, the circulation path of air flow of an air path is changed, low load is realized, and high potential is controlled by a starting working condition; the durability of the fuel cell can be improved, waste heat is recycled, and the energy utilization rate is improved.

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 demand more and more energy, energy depletion and environmental pollution are becoming increasingly serious. As one of the new energy sources, hydrogen has excellent environmental protection effects, with 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, have high energy conversion efficiency, are clean and environmentally friendly, have simple structures, and have low noise, they have been widely used in transportation, distributed power generation, and portable electronic devices. In the actual operation of fuel cells, in addition to outputting electrical energy, a large amount of waste heat is also generated. If this part of waste heat can be effectively recovered, it can not only improve energy utilization, but also further reduce operating costs and environmental impacts.

[0003] At present, the research on waste heat recovery of fuel cells is mainly focused on water-cooled fuel cell systems, which use circulating cooling water to remove the waste heat generated by the fuel cell and then use it for secondary utilization such as heating and power generation. Since the water cooling system requires auxiliary equipment such as water pumps and cooling pipes, the complexity and maintenance cost of the system are increased. At the same time, for some application scenarios that require lightweight and high portability, the use of water cooling systems will be limited.

[0004] Air-cooled fuel cells have broad application prospects in portable power supplies, drones, electric bicycles, etc. due to their simple structure, easy maintenance, and strong adaptability. For air-cooled fuel cells, current research mainly focuses on how to improve air cooling effect and heat dissipation efficiency. Waste heat recovery technology is not yet mature, and there is little secondary use of waste heat. 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 intake path, and the main air intake path is connected in parallel with the air intake 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 1, port 2 of the three-way valve 1, and the cathode inlet of the 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, the port 1 of the three-way valve 2, the port 2 of the three-way valve 2, the port 5 of the six-way valve, the port 6 of the six-way valve, and the hot end assembly are connected in sequence;

[0012] On the air 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 three-way valve 2 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] Compare 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, it is determined whether the state of the fuel cell in which the stack is located is a low load, startup state; if the determination result is yes, steps S40 and S60 are sequentially executed; if the determination result is no, steps S50 and S60 are sequentially executed; 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 port 5 and port 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 port 1 to port 2 of the six-way valve, and connecting port 5 to port 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 the present invention adopts a six-way valve and a heat exchanger, which has a compact structure, simplifies the system design, and reduces the weight and maintenance cost. High voltage limit control is performed on low load and startup conditions to improve the durability of the system. While improving the operating performance of the fuel cell stack, the secondary utilization of waste heat can be achieved. By transporting high-temperature gas to the heat-using end components, the overall energy utilization, economy and sustainability of the system are improved. 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 drawings required for use in the embodiments will be briefly introduced below. 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 creative work.

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

[0028] Figure 2 It is a schematic diagram of the control mode of the controller;

[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 be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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 to improve 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 The present 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 including 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 to the air inlet branch in parallel. The cathode outlet of the stack 5 is connected to the main air outlet path, and the main air outlet path is connected to the air outlet branch in parallel.

[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 26 are connected in sequence.

[0039] The term "connected in sequence" as mentioned above refers to connecting in sequence through pipelines in the order of description 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 on-off between the ports of the six-way valve 3, thereby changing the direction of the airflow according to actual needs, using the heat of the airflow flowing out of the cathode outlet of the stack 5 to preheat the airflow flowing into the cathode inlet of the stack 5, or to supply heat to the hot end assembly 8, thereby realizing the recovery of waste heat. The above control process can be controlled manually or automatically.

[0042] As a possible example, in this embodiment, in order to improve the automation level of the system, 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 stack 5. The first temperature sensor is electrically connected to the controller for transmitting the monitoring result to the controller. The controller is electrically connected to the six-way valve 3 for controlling the connection mode of the six-way valve 3 to control the air path system.

[0043] Exemplarily, the control method 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 stack 5 is used to heat the low-temperature air at the cathode inlet of the stack 5 through the heat exchanger 7, thereby increasing the temperature of the gas entering the stack 5 to maintain the fuel cell at a suitable operating temperature and improve the performance of the stack 5. The high-temperature gas after passing through the heat exchanger 7 is continuously mixed with the gas at the cathode outlet of the stack 5 and transported to the hot end assembly 8 to continue to recover waste heat, thereby improving energy utilization.

[0046] If T0>T1 (ie, waste heat recovery is not required), it is determined whether the state of the fuel cell where the fuel cell stack 5 is located is 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 operation step are as follows:

[0050] S10, connect port 1 to port 3 of the six-way valve 3, connect port 5 to port 4 of the six-way valve 3, and connect port 5 to port 6 of the six-way valve 3. At this time, the parallel air inlet branch and the parallel air outlet branch are enabled, and the heat exchanger 7 works, using the heat of the airflow flowing out of the cathode outlet of the battery stack 5 to preheat the airflow flowing into the cathode inlet of the battery stack 5.

[0051] S20, adjusting the valve opening between port 5 and port 4 of the six-way valve 3 so that the monitoring result T3 of the second temperature sensor gradually approaches the target stack entry temperature T2 preset in the controller. This adjustment step is to improve the heat exchange efficiency so that the monitoring result T3 of the second temperature sensor is heated to the target stack entry temperature T2 as soon as possible.

[0052] S30, start the hot end assembly 8. When the heat of the airflow flowing out of the cathode outlet of the stack 5 is sufficient to raise the monitoring result T3 of the second temperature sensor 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 to further utilize the waste heat. It should be noted that step S20 is located before step S30, that is, the fuel cell stack entry temperature and the stack power generation efficiency are ensured first, and then the waste heat output is considered.

[0053] S40, connect port 1 to port 2 of the six-way valve 3, connect port 5 to port 3 of the six-way valve 3, and connect port 5 to port 6 of the six-way valve 3. In this step, the airflow flowing out of the cathode outlet of the stack 5 is directly guided to the air intake branch through the six-way valve 3, and the high-humidity and low-oxygen concentration gas at the cathode outlet of the stack 5 is sent back to the cathode inlet of the stack 5, and mixed with the fresh air from the fan, so as to limit the high potential and increase the humidity, thereby improving the durability of the fuel cell.

[0054] S50, connecting port 1 to port 2 of the six-way valve 3, and connecting port 5 to port 6 of the six-way valve 3. This step directly directs the gas flow from the cathode outlet of the stack 5 to the hot end assembly 8, without using the waste heat to increase the gas flow 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 used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An air-cooled fuel cell waste heat recovery system, characterized in that: It includes a battery stack, an air path system and a hot end component, wherein 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 intake path, and the main air intake path is connected in parallel with the air intake 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 1, port 2 of the three-way valve 1, and the cathode inlet of the 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, the port 1 of the three-way valve 2, the port 2 of the three-way valve 2, the port 5 of the six-way valve, the port 6 of the six-way valve, and the hot end assembly are connected in sequence; On the air 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 three-way valve 2 are connected in sequence.

2. The air-cooled fuel cell waste heat recovery system according to claim 1, characterized in that: It 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, 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, and is used to transmit the monitoring result to the controller; the controller is electrically connected to the six-way valve, and is used to control the connection mode of the six-way valve to control the air path system.

3. The air-cooled fuel cell waste heat recovery system according to claim 2, characterized in that: The control mode of the controller is as follows: Compare the monitoring result T0 of 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, it is determined whether the state of the fuel cell in which the stack is located is a low load, startup state; if the determination result is yes, steps S40 and S60 are sequentially executed; if the determination result is no, steps S50 and S60 are sequentially executed; 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 port 5 and port 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; 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 port 1 to port 2 of the six-way valve, and connecting port 5 to port 6 of the six-way valve; S60, closing the hot end assembly.

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