Heat management device for fuel cell based on countercurrent exchange principle

Abstract

The invention discloses a heat management device for a fuel cell based on a countercurrent exchange principle. The device comprises a heat exchange system consisting of a plurality of heat exchange plates, and is used for realizing heat exchange between first circulating water to enter a fuel cell stack and second circulating water flowing out of the stack, so that the working temperature of the fuel cell is improved and maintained, and the cold start efficiency of the cell is accelerated. Feather-shaped distribution channels are formed in the heat exchange plate and comprise a main channel, a plurality of inclined channels and two outer edge channels, the main channel is located on the long central axis of the heat exchange plate, and the two outer edge channels are parallel to the main channel and distributed on the two sides of the main channel. A part of liquid flowing into the main channel is shunted into the outer edge channel through the inclined channels and finally converged to the downstream of the main channel. Through the design of the feather-shaped distribution channels, the heat conduction efficiency of the heat exchange plate is remarkably improved, and more efficient fuel cell temperature management is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a thermal management device for a fuel cell based on the countercurrent exchange principle. Background Art

[0002] The process of successfully starting a proton exchange membrane fuel cell at a low temperature (below 0°C) and running it to the operating temperature (70-80°C) is called a "cold start". Due to the needs of the working environment, the cold start efficiency of the fuel cell is one of the important issues to improve the practicality of fuel cell vehicles. Since the cathode redox reaction (ORR) in the fuel cell produces liquid water, if the water generated by the reaction cannot be removed from the stack in time, under low temperature conditions, the water will freeze and block the catalyst layer, gas diffusion layer and flow channel in turn, resulting in difficulty in restarting the stack in a low temperature environment, which is specifically manifested as a decrease in the electrochemical reaction rate, slow start-up and even restart failure. At the same time, the repeated phase change process of water-ice caused by multiple starts and stops will damage the proton exchange membrane, causing an increase in contact resistance and a decrease in sealing, and ultimately causing irreversible performance degradation.

[0003] At present, the mainstream methods for improving the cold start efficiency of fuel cells are generally divided into two points based on whether they rely on auxiliary heating methods: self-starting and assisted starting. Self-starting is completely dependent on the heat released by the electrochemical reaction and does not require additional energy input. Therefore, the energy utilization efficiency is high, but it is necessary to wait for enough heat to be generated inside the battery to increase the temperature. The heating efficiency is very low, causing the battery to be in a low-temperature operating state for a long time, and it does not fundamentally solve the adverse effects of long-term low-temperature operation on the durability of the battery; assisted starting refers to the process of fuel cell startup, which provides heat through an external heat source (such as an electric heater, heat exchanger, etc.) to help the battery quickly reach the normal operating temperature, but due to the need for external energy input, the energy utilization efficiency of assisted starting is relatively low.

[0004] How to speed up the cold start efficiency of the battery while reducing the power of the external heat source or even not relying on the external heat source is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The present invention provides a thermal management device for a fuel cell based on the countercurrent exchange principle, which is used to accelerate the cold start efficiency of the battery while reducing the power of an external heat source or even not relying on an external heat source.

[0006] To achieve the above object, the present invention first provides a thermal management device for a fuel cell based on the countercurrent exchange principle, the thermal management device comprising:

[0007] A shell body, the interior of which is hollow, the top and bottom of the shell body are sealed by a first cover plate and a second cover plate respectively, the first cover plate is provided with a first water inlet and a second water outlet, and the second cover plate is provided with a first water outlet and a second water inlet;

[0008] A heat exchange system, which is located in the shell, and the first water inlet and the first water outlet are connected to the heat exchange system through a connecting pipe;

[0009] In the working state, the first circulating water flows into the heat exchange system in the shell through the first water inlet through the connecting pipe and flows out from the first water outlet, and the second circulating water enters the shell through the second water inlet and flows out from the second water outlet, thereby realizing countercurrent heat exchange between the first circulating water and the second circulating water;

[0010] The heat exchange system is composed of a number of heat exchange plates that are spaced apart and arranged in parallel. Connecting pipes are installed at both ends of the heat exchange plates. The connecting pipes are connected to the inside of the heat exchange plates. Adjacent heat exchange plates are connected to each other through the connecting pipes.

[0011] The heat exchange plate has a feather-shaped distribution channel inside, and the feather-shaped distribution channel includes a main channel, a plurality of oblique channels and two outer edge channels. The main channel is located on the long central axis of the heat exchange plate, and the two outer edge channels are parallel to the main channel and distributed on both sides of the main channel. A portion of the liquid flowing into the main channel is diverted to the outer edge channels through the plurality of oblique channels, and finally converges to the downstream of the main channel.

[0012] Preferably, the oblique channel is inclined toward the downstream direction of the main channel, and the angle between the two is 25° to 75°.

[0013] Preferably, the plurality of oblique channels are distributed in parallel and at intervals between the main channel and the outer edge channel, and two ends of the oblique channels are respectively connected to the main channel and the outer edge channel.

[0014] Preferably, the spacing distance between adjacent oblique channels is 15 mm to 25 mm.

[0015] Preferably, the radius of the oblique channel is 4 mm to 6 mm.

[0016] Preferably, the length of the main channel is 80% to 90% of the length of the heat exchange plate, and the length of the outer edge channel is 80% to 90% of the length of the main channel.

[0017] Preferably, the radius of the main channel and the outer edge channel is 16 mm to 25 mm.

[0018] Preferably, the plate surface of the heat exchange plate is parallel to the horizontal plane of the first cover plate.

[0019] Preferably, a positioning protrusion is provided on the inner side wall of the shell in a direction perpendicular to the horizontal plane of the first cover plate, for positioning and auxiliary supporting the heat exchange plate.

[0020] Preferably, the material of the heat exchange plate includes aluminum or aluminum alloy.

[0021] Compared with the prior art, the beneficial effects of the present invention include at least:

[0022] The present invention provides a thermal management device for a fuel cell based on the countercurrent exchange principle. The device includes a heat exchange system composed of a plurality of heat exchange plates, through which the first circulating water with a relatively low temperature to be introduced into the fuel cell stack is countercurrently heat exchanged with the second circulating water with a relatively high temperature flowing out of the stack, thereby increasing the temperature of the first circulating water, which is beneficial to increasing and maintaining the operating temperature of the fuel cell itself, achieving the purpose of accelerating the cold start efficiency of the battery, improving the temperature uniformity of the battery in a cold environment, and thus improving the performance and life of the battery.

[0023] Crucially, the present invention has made an innovative design to the structure of the liquid circulation channel inside the heat exchange plate, and arranged the liquid circulation channel inside the heat exchange plate to be distributed in a feather-like manner, thereby greatly improving the heat exchange efficiency of the liquid inside and outside the heat exchange plate, achieving efficient utilization of the reaction heat of the fuel cell stack, and further achieving more efficient fuel cell temperature management, thereby improving the cold start efficiency and stability of the proton exchange membrane fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic cross-sectional view of a thermal management device for a fuel cell based on the countercurrent exchange principle provided in one embodiment of the present invention.

[0025] Figure 2 for Figure 1 A bottom view schematically showing the structure of the device of the embodiment.

[0026] Figure 3 A schematic plan view of a heat exchange plate structure provided in one embodiment of the present invention.

[0027] Figure 4 A schematic cross-sectional view of a heat exchange plate structure provided in one embodiment of the present invention.

[0028] Figure 5 A fuel cell system is provided in one embodiment of the present invention.

[0029] Figure ID

[0030] Shell 1, first cover plate 11, second cover plate 12, rubber sealing ring 13, positioning protrusion 14, heat exchange system 2, first water inlet 31, first water outlet 32, second water inlet 41, second water outlet 42, connecting pipe 5, main channel 61, oblique channel 62, outer edge channel 63, confluence channel 64, opening 7, groove 8, temperature sensors 91, 92; battery stack 101, air-cooled radiator 102, heater 103, three-way valve 104, water tank 105, host computer 106, water pump 107. DETAILED DESCRIPTION

[0031] 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.

[0032] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0033] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0034] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] As described in the background technology, battery cold start can be divided into self-start and auxiliary start. The self-start method has high energy utilization efficiency, but the battery heating rate is slow, and long-term low-temperature operation will reduce the battery durability; the auxiliary start method can quickly reach the normal operating temperature of the battery with the help of an external heat source, but the energy utilization efficiency is relatively low. Therefore, how to improve the cold start efficiency of the battery stack while reducing the power of the external heat source or even not relying on the external heat source is a technical problem that needs to be solved in this field.

[0036] To solve the above problems, Figure 1 to Figure 2 As shown, an embodiment of the present invention provides a thermal management device 100 for a fuel cell based on the countercurrent exchange principle, including: a housing 1, a heat exchange system 2, a first water inlet 31 and a first water outlet 32, a second water inlet 41 and a second water outlet 42.

[0037] The shell 1 is hollow inside, and the top and bottom of the shell 1 are sealed respectively by a first cover plate 11 and a second cover plate 12. In some embodiments, a rubber sealing ring 13 is added at the sealing connection between the first cover plate 11, the second cover plate 12 and the shell to improve the sealing performance.

[0038] The heat exchange system 2 is located in the housing 1. Figure 1 As shown, it is composed of a plurality of heat exchange plates 21 that are spaced and parallel in the vertical direction, and the panels of the heat exchange plates 21 are parallel to the horizontal plane of the first cover plate 11. Connecting pipes 5 are installed at both ends of the heat exchange plates 21, and the connecting pipes 5 are connected to the inside of the heat exchange plates 21. Adjacent heat exchange plates 21 are connected to each other through the connecting pipes 5. It should be noted that the connecting pipes connecting two adjacent heat exchange plates 21 are not integrated.

[0039] The first water inlet 31 and the second water outlet 42 are arranged on the first cover plate 11, and the first water outlet 32 ​​and the second water inlet 41 are arranged on the second cover plate 12. The second water inlet 41 and the second water outlet 42 are connected to the interior of the housing 1. The first water inlet 31 and the first water outlet 32 ​​are connected to the heat exchange system 2 through the connecting pipe 5, respectively. Specifically, Figure 1 As shown, the first water inlet 31 is connected to the heat exchange plate 21 closest to the first cover plate 11 through the connecting pipe 5 , and the first water outlet 32 ​​is connected to the heat exchange plate 21 closest to the second cover plate 12 through the connecting pipe 5 .

[0040] In the working state, the first circulating water with a relatively low temperature to be entered into the fuel cell stack flows into the heat exchange plate 21 of the exchange system 2 from the first water inlet 31 through the connecting pipe 5, and finally flows out through the first water outlet 32. The second circulating water with a relatively high temperature flowing out of the stack enters the housing 1 from the second water inlet 41, and finally flows out from the second water outlet 42. The first circulating water and the second circulating water realize countercurrent heat exchange through the heat exchange plate 21 (i.e., the heat exchange system 2). Under the influence of the temperature gradient, the second circulating water with a higher temperature will transfer part of the heat to the first circulating water. In this process, the reaction heat of the stack and the heat of the external heat source (if any) are utilized.

[0041] It can be understood that compared with the first circulating water that has not passed through the heat exchange system 2, the temperature of the first circulating water that has passed through the heat exchange system 2 will increase, which can be beneficial to the rapid increase and maintenance of the fuel cell temperature and improve the cold start efficiency of the battery. Therefore, for self-starting fuel cells, the device of the present invention can greatly reduce its low-temperature operation time and improve the durability of self-starting fuel cells; for auxiliary start-up fuel cells, the device of the present invention can reduce its high power demand for external heat sources and improve the energy utilization efficiency of the entire stack system. In addition, the fuel cell circulating water port is at the end plate. Since the device of the present invention can reduce the temperature difference between the first circulating water and the second circulating water, it is beneficial to reduce the temperature distribution difference of the battery end plate, and ultimately reduce the impact of the end plate effect on the performance of the fuel cell.

[0042] It should be noted that in order to improve the countercurrent heat exchange efficiency of the device of the present invention and increase the contact time of the liquid inside and outside the heat exchange plate, the first water inlet 31 and the first water outlet 32 ​​are distributed diagonally in the entire device, and the second water inlet 41 and the second water outlet 42 are also distributed diagonally. Figure 1 As shown, the first water inlet 31 is located at the left end of the first cover plate 11, and the first water outlet 32 ​​is located at the right end of the second cover plate 12; the second water inlet 41 is located at the right end of the second cover plate 12, and the second water outlet 42 is located at the left end of the first cover plate 11.

[0043] like Figure 1 As shown, in some embodiments, in order to monitor the temperature of the first circulating water and the second circulating water of the heat exchange, temperature sensors 91 and 92 are respectively provided at the first water outlet 32 ​​and the second water inlet 41 .

[0044] More importantly, the present invention further improves the utilization efficiency of the reaction heat of the fuel cell stack by innovatively designing the structure of the liquid circulation channel inside the heat exchange plate 21, so that the goal of "accelerating the cold start efficiency of the battery while reducing the power of the external heat source or even not relying on the external heat source" can be achieved.

[0045] like Figure 3 to Figure 4 As shown, the heat exchange plate 21 has a feather-shaped distribution channel inside, and the feather-shaped distribution channel includes a main channel 61, a plurality of oblique channels 62 and two outer edge channels 63. The main channel 61 is located on the long central axis of the heat exchange plate 21, and its upstream port and downstream port are connected with the openings 7 at both ends of the heat exchange plate 21. The openings 7 vertically penetrate the horizontal panel of the heat exchange plate 21, and the openings 7 are matched and connected with the connecting pipe 5; the two outer edge channels 63 are parallel to the main channel 61 and distributed on both sides of the main channel 61; the plurality of oblique channels 62 are distributed in parallel and spaced apart between the main channel 61 and the outer edge channel 63, and the two ends of the oblique channel 62 are respectively connected with the main channel 61 and the outer edge channel 63.

[0046] In the working state, when the first circulating water flows into the heat exchange plate 21 from the opening 7 at the left end of the heat exchange plate 21, it first flows to the upstream of the main channel 61. When it flows further to the downstream of the main channel 61, a part of the first circulating water will be diverted to the outer edge channel 63 through a number of oblique channels 62 distributed on both sides of the main channel 61, increasing the contact area and contact time between the first circulating water and the second circulating water, which is conducive to improving the heat conduction efficiency of both and achieving more efficient fuel cell temperature management. The first circulating water diverted to the outer edge channel 63 eventually converges to the downstream port of the main channel 61 through the confluence channel 64, and further flows into other heat exchange plates 21 or the first water outlet 32 ​​through the connecting pipe 5.

[0047] like Figure 3 As shown, in some embodiments, the oblique channel 62 is oriented toward the downstream direction of the main channel 61 ( Figure 3 The inclined channels 62 are inclined in the right direction (in the middle), the included angle between the two is 50±25° (i.e., 25° to 75°), and the spacing distance between adjacent inclined channels 62 is 15mm to 25mm.

[0048] In some embodiments, the length of the main channel 61 is 80% to 90% of the length of the heat exchange plate 21, and the length of the outer edge channel 63 is 80% to 90% of the length of the main channel 61. Furthermore, the cross-sections of the main channel 61, the oblique channel 62, the outer edge channel 63 and the converging channel 64 are circular, the radius of the main channel 61, the outer edge channel 63 and the converging channel 64 is 16 mm to 25 mm, and the radius of the oblique channel 62 is 4 mm to 6 mm.

[0049] In some embodiments, the heat exchange plate 21 is made of aluminum or aluminum alloy.

[0050] In some embodiments, such as Figure 1 and Figure 2As shown, in a direction perpendicular to the horizontal plane of the first cover plate 11, positioning protrusions 14 are provided on the front and rear inner side walls of the shell for positioning and auxiliary supporting the plurality of heat exchange plates 21. Figure 3 As shown, grooves 8 that match and engage with the positioning protrusions 14 are provided on the upper and lower sides of the heat exchange plate 21 .

[0051] In some embodiments, the shell 1 has a rounded rectangular shape and is wrapped with a heat insulating layer (made of aluminum silicate wool).

[0052] Figure 5 An application scenario of the device of the present invention is provided. The fuel cell system includes: a battery stack 101, a thermal management device 100 provided by the present invention, an air-cooled radiator 102, a heater 103, a three-way valve 104, a water tank 105, a host computer 106 and a water pump 107. Among them, the heater 103 is a heat source for auxiliary starting when the battery is started, and the three-way valve 104 is used to switch the circulation loop: when the battery stack 101 is started or on standby, the second circulating water discharged from the battery stack 101 is led to the heater 103; when the temperature of the battery stack 101 exceeds the operating temperature, the second circulating water discharged from the battery stack 101 is introduced into the air-cooled radiator 102 for cooling operation under the control of the host computer 106; the water tank 105 is used to store circulating water and plays a certain buffering role.

[0053] The thermal management device of the present invention is arranged upstream of the three-way valve 104 and downstream of the water pump 107. When the battery is started or on standby, the first circulating water with a relatively low temperature to be entered into the battery stack 101 and the second circulating water with a relatively high temperature flowing out of the battery stack 101 will undergo countercurrent heat exchange through the thermal management device 100 of the present invention, so that the temperature of the first circulating water will be increased, which will be beneficial to the rapid increase and maintenance of the temperature of the fuel cell and improve the cold start efficiency of the battery.

[0054] It should be noted that the first circulating water and the second circulating water in this article are essentially the circulating water of the entire system. The second circulating water discharged from the battery stack 101 eventually flows into the water tank 105 and mixes with the circulating water originally in the tank. Under the action of the water pump, the circulating water in the water tank 105 is pumped out to form the first circulating water to be entered into the battery stack 101. After the first circulating water passes through the battery stack 101 and is discharged, the second circulating water is formed again.

[0055] In summary, the present invention provides a thermal management device for fuel cells based on the countercurrent exchange principle. The device includes a heat exchange system composed of a plurality of heat exchange plates, and the feather-shaped liquid flow channels in the heat exchange plates greatly improve the heat exchange efficiency of the liquid inside and outside the heat exchange plates, and achieve efficient utilization of the heat of the fuel cell reaction, thereby achieving more efficient fuel cell temperature management, achieving the purpose of accelerating the cold start efficiency of the battery, improving the temperature uniformity of the battery in a cold environment, and thus improving the performance and life of the battery.

[0056] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A thermal management device for a fuel cell based on the countercurrent exchange principle, characterized in that: The thermal management device comprises: A shell body, the interior of which is hollow, the top and bottom of the shell body are sealed by a first cover plate and a second cover plate respectively, the first cover plate is provided with a first water inlet and a second water outlet, and the second cover plate is provided with a first water outlet and a second water inlet; A heat exchange system, which is located in the shell, and the first water inlet and the first water outlet are connected to the heat exchange system through a connecting pipe; In the working state, the first circulating water flows into the heat exchange system in the shell through the first water inlet through the connecting pipe and flows out from the first water outlet, and the second circulating water enters the shell through the second water inlet and flows out from the second water outlet, thereby realizing countercurrent heat exchange between the first circulating water and the second circulating water; The heat exchange system is composed of a number of heat exchange plates that are spaced apart and arranged in parallel. Connecting pipes are installed at both ends of the heat exchange plates. The connecting pipes are connected to the inside of the heat exchange plates. Adjacent heat exchange plates are connected to each other through the connecting pipes. The heat exchange plate has a feather-shaped distribution channel inside, and the feather-shaped distribution channel includes a main channel, a plurality of oblique channels and two outer edge channels. The main channel is located on the long central axis of the heat exchange plate, and the two outer edge channels are parallel to the main channel and distributed on both sides of the main channel. A portion of the liquid flowing into the main channel is diverted to the outer edge channels through the plurality of oblique channels, and finally converges to the downstream of the main channel.

2. The thermal management device for a fuel cell based on the countercurrent exchange principle as claimed in claim 1, characterized in that: The oblique channel is inclined toward the downstream direction of the main channel, and the angle between the two is 25° to 75°.

3. The thermal management device for a fuel cell based on the countercurrent exchange principle as claimed in claim 1, characterized in that: The plurality of oblique channels are distributed in parallel and at intervals between the main channel and the outer edge channel, and two ends of the oblique channels are respectively connected to the main channel and the outer edge channel.

4. The thermal management device for a fuel cell based on the countercurrent exchange principle as claimed in claim 3, characterized in that: The spacing distance between adjacent oblique channels is 15 mm to 25 mm.

5. The thermal management device for a fuel cell based on the countercurrent exchange principle as claimed in claim 1, characterized in that: The radius of the oblique channel is 4 mm to 6 mm.

6. The thermal management device for a fuel cell based on the countercurrent exchange principle as claimed in claim 1, characterized in that: The length of the main channel is 80% to 90% of the length of the heat exchange plate, and the length of the outer edge channel is 80% to 90% of the length of the main channel.

7. The thermal management device for a fuel cell based on the countercurrent exchange principle as claimed in claim 1, characterized in that: The radius of the main channel and the outer edge channel is 16 mm to 25 mm.

8. The thermal management device for a fuel cell based on the countercurrent exchange principle as claimed in claim 1, characterized in that: The plate surface of the heat exchange plate is parallel to the horizontal plane of the first cover plate.

9. The thermal management device for a fuel cell based on the countercurrent exchange principle as claimed in claim 8, characterized in that: A positioning protrusion is provided on the inner side wall of the shell in a direction perpendicular to the horizontal plane of the first cover plate, for positioning and auxiliary supporting the heat exchange plate.

10. The thermal management device for a fuel cell based on the countercurrent exchange principle as claimed in claim 1, characterized in that: The material of the heat exchange plate includes aluminum or aluminum alloy.

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