Fuel cell stack, fuel cell engine and automobile

Abstract

The invention provides a fuel cell stack, a fuel cell engine and an automobile, and relates to the technical field of fuel cells, the fuel cell stack comprises a heat pipe group, the heat pipe group at least comprises one heat pipe, the heat pipe evaporation section of each heat pipe in the heat pipe group is located at a coolant outlet of the fuel cell stack, and the heat pipe evaporation section of each heat pipe is located at the coolant outlet of the fuel cell stack. A condensation section of the heat pipe is positioned at a coolant inlet of the fuel cell stack; the heat pipe works under a target working condition, and the target working condition comprises at least one of a low-temperature starting working condition, a cold-state load pulling working condition and a shutdown purging working condition. When the temperature of the cooling medium at the coolant outlet is higher than the evaporation temperature of the heat pipe, the heat of the high-temperature coolant outlet of the coolant outlet is transferred to the coolant inlet through the heat pipe and exchanges heat with the low-temperature cooling medium at the coolant inlet, so that the temperature of the cooling medium at the coolant inlet is increased; and the temperature difference between the coolant outlet and the coolant inlet is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a fuel cell stack, a fuel cell engine and an automobile. Background Art

[0002] Proton exchange membrane fuel cells have the advantages of wide fuel sources, zero pollution, fast response and high efficiency, and are regarded as one of the most potential power sources. Proton exchange membrane fuel cells use high-purity hydrogen as fuel and oxygen in the air as oxidant, and their electrochemical reaction products are pure water. Generally, the suitable operating temperature of a fuel cell is 70-90°C. When the battery temperature is greater than 90°C, there is a serious risk of dehydration of the proton exchange membrane or sulfonic acid resin, resulting in the problem of "membrane drying". When the battery temperature is less than 70°C, there is a risk of condensate accumulation in the porous medium, resulting in the problem of "water flooding". Therefore, how to stabilize the operating temperature of the fuel cell at 70-90°C, that is, rapid heating at low temperature and rapid cooling at high temperature, has become an important part of thermal management.

[0003] During the rapid heating process of a fuel cell, there is generally a phenomenon that the inlet temperature of the stack coolant is relatively low, and the temperature difference between the inlet and outlet of the stack coolant is relatively large, resulting in voltage fluctuations or even the problem of "single low", reduced power generation efficiency, and affecting the operating reliability of the fuel cell. For example, during a low-temperature start at -30°C, since the coolant in the external cooling circuit of the stack before startup is at -30°C, after the coolant starts to flow through the control of the water pump, the inlet temperature of the stack coolant remains close to -30°C for a period of time. The coolant at sub-zero temperature entering the stack may cause the temperature of the active area near the inlet of the stack coolant to drop below zero, resulting in icing and voltage fluctuations. In addition, during the shutdown purge process, in order to quickly dry the stack, it is usually required that the stack temperature be maintained at a relatively high level, such as 50-70°C, especially for cold purges below zero. Therefore, it is expected that less heat is carried away by the external cooling circuit after the coolant flows through the stack during the cold purge process. However, during the actual cold purge below zero, the heat carried away by the external cooling circuit of the stack causes the outlet temperature of the stack coolant to become lower and lower, reducing the drying rate of the membrane electrode, increasing the purge energy consumption and reducing the success rate of the next low-temperature start.

[0004] Therefore, how to improve the problem of relatively low inlet temperature of the stack coolant and relatively large temperature difference between the inlet and outlet of the stack coolant under specific working conditions has become one of the technical problems that need to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a fuel cell stack, a fuel cell engine and an automobile to increase the inlet temperature of the coolant of the fuel cell stack, reduce the temperature difference between the outlet temperature of the coolant and the inlet temperature of the coolant under specific working conditions.

[0006] To achieve the above object, the embodiments of the present invention provide the following technical solutions:

[0007] A fuel cell stack, comprising:

[0008] A heat pipe group, the heat pipe group includes at least one heat pipe, the heat pipe evaporation sections of the heat pipes in the heat pipe group are located at the coolant outlet of the fuel cell stack, and the condensation sections of the heat pipes are located at the coolant inlet of the fuel cell stack;

[0009] The heat pipe is a heat pipe operating under target conditions, and the target conditions include at least one of a low-temperature startup condition, a cold-state load pulling condition, and a shutdown purge condition.

[0010] Optionally, in the above fuel cell stack, when the target condition is a low-temperature startup condition, the heat pipe group includes a first heat pipe;

[0011] The evaporation temperature of the first heat pipe is not lower than a preset low-temperature startup temperature and not higher than a first upper limit temperature, and the first upper limit temperature is the lowest temperature of the coolant outlet of the fuel cell stack marked in advance when the fuel cell stack successfully starts up at low temperature.

[0012] Optionally, in the above fuel cell stack, when the target condition is a cold-state load pulling condition, the heat pipe group includes a second heat pipe;

[0013] The evaporation temperature of the second heat pipe is higher than the first upper limit temperature and not higher than a second upper limit temperature, and the second upper limit temperature is not higher than the thermostat opening temperature.

[0014] Optionally, in the above fuel cell stack, when the target condition is a shutdown purge condition, the heat pipe group includes a third heat pipe;

[0015] The evaporation temperature of the third heat pipe is consistent with a third temperature, and the third temperature is not lower than a purge recommended lower limit temperature and not higher than a purge recommended upper limit temperature.

[0016] Optionally, in the above fuel cell stack, the heat pipes in the heat pipe group are integrally connected in parallel in the intake assembly of the fuel cell stack.

[0017] Optionally, in the above fuel cell stack, the heat pipes in the heat pipe group are arranged on the intake end plate of the fuel cell stack, on the insulating plate of the fuel cell stack, on the current collector plate of the fuel cell stack, at the interface between the intake end plate and the insulating plate, at the interface between the insulating plate and the current collector plate, or on the cooling circuit outside the fuel cell stack.

[0018] Optionally, in the above fuel cell stack, grooves or through holes matching the shape of the heat pipe are provided on the intake end plate, insulating plate, or current collector plate of the fuel cell stack.

[0019] A fuel cell engine includes any one of the above fuel cell stacks.

[0020] A vehicle includes any one of the above fuel cell engines.

[0021] Based on the above technical solution, in the solution provided by the embodiment of the present invention, by arranging a heat pipe group in the fuel cell stack, the heat pipe group includes at least one heat pipe, the heat pipe evaporation section of the heat pipe is located in the coolant outlet of the fuel cell stack, and the heat pipe condensation section of the heat pipe is located in the coolant inlet of the fuel cell stack. When the temperature of the cooling medium at the coolant outlet is greater than the evaporation temperature of the heat pipe, the heat of the high-temperature coolant at the coolant outlet is transferred to the coolant inlet through the heat pipe, and heat exchange is performed with the low-temperature cooling medium at the coolant inlet to increase the temperature of the cooling medium at the coolant inlet, thereby reducing the temperature difference between the coolant outlet and the coolant inlet. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0023] Figure 1 Shows the large temperature difference phenomenon between the coolant inlet and the coolant outlet during the low-temperature start-up process of the traditional fuel cell stack structure (without heat pipes);

[0024] Figure 2 Is an exploded view of the fuel cell stack disclosed in the embodiment of the invention;

[0025] Figure 3 Is a top view of the fuel cell stack disclosed in the embodiment of the present invention;

[0026] Figure 4 Is Figure 3 The cross-sectional view along the A-A direction in

[0027] Figure 5 Is a schematic diagram of the cooling circuit of the fuel cell stack disclosed in the embodiment of the present invention;

[0028] Figure 6 Is a temperature change curve graph of the cooling medium at the coolant outlet and the coolant inlet during the control process of the fuel cell stack starting at -30°C;

[0029] Figure 7 Is a temperature change curve graph of the cooling medium at the coolant outlet and the coolant inlet during the cold-state loading process of the fuel cell stack;

[0030] Figure 8 It is a graph of the temperature change of the cooling medium at the coolant outlet and the coolant inlet during the purging process of the fuel cell stack;

[0031] Figure 9 It is a schematic structural diagram of a multi - heat - pipe integrated fuel cell stack disclosed in an embodiment of the present invention. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0033] In the traditional fuel cell stack structure, the coolant with a lower temperature in the external cooling circuit of the fuel cell stack enters the fuel cell stack. After heat exchange with the battery cells, it becomes a coolant with a higher temperature and flows into the external cooling circuit of the fuel cell stack from the coolant outlet 5 on the intake end plate 1. Therefore, the temperature difference between the coolant inlet and the coolant outlet in the traditional fuel cell stack structure is relatively large. Figure 1 Illustrates the situation of the coolant inlet temperature and the coolant outlet temperature on the cooling circuit during the low - temperature startup process of a traditional fuel cell stack at - 30°C, Figure 1 The coolant outlet temperature in [reference] refers to the temperature of the cooling medium at the coolant outlet, the coolant inlet temperature refers to the temperature of the cooling medium at the coolant inlet, the coolant pump refers to the coolant pump in the circulation system, and the current refers to the current output by the fuel cell stack. Since the temperature of the cooling medium at the coolant inlet is relatively low at the initial stage of low - temperature startup and is below zero for a period of time, while the temperature of the cooling medium flowing out of the coolant outlet is relatively high due to the heating of the stack, the temperature difference between the coolant inlet and outlet is relatively large.

[0034] This application provides a fuel cell stack. Heat pipes are arranged in the fuel cell stack, and the heat pipes are used to improve the problem that the coolant inlet temperature of the fuel cell stack is too low and the temperature difference between the coolant inlet and the coolant outlet is relatively large. By installing a heat pipe group between the coolant inlet and the coolant outlet of the fuel cell stack intake assembly, and the evaporation temperature of the heat pipe can be set according to the usage requirements to meet different working conditions. In addition, heat pipes with different evaporation temperatures can also be installed between the coolant inlet and the coolant outlet of the fuel cell stack intake assembly to take into account the use of multiple working conditions.

[0035] See Figure 2 、 Figure 3 and Figure 4, this application discloses a fuel cell stack, which includes an intake end plate 1, an insulating plate 2, a current collector plate 3, and a heat pipe group 13. The heat pipe group 13 includes at least one heat pipe. The heat pipe evaporation section 11 of each heat pipe in the heat pipe group 13 is located at the coolant outlet 5 of the fuel cell stack, and the condensation section of the heat pipe is located at the coolant inlet 8 of the fuel cell stack; the heat pipe is a heat pipe operating under target conditions, and the target conditions include at least one of a low-temperature start-up condition, a load condition, and a shutdown purge condition. Among them, Figure 2 10 in it is the cooling medium.

[0036] Regarding the intake end plate 1, the intake end plate 1 is usually formed by processing metal materials such as aluminum and stainless steel to support the fuel cell stack cells and play a role in sealing the medium channels. See Figures 2-4 , there are 6 fluid holes on the intake end plate 1, and these 6 fluid holes are respectively a hydrogen inlet 6, a hydrogen outlet 9, an air inlet 7, an air outlet 4, a coolant inlet 8, and a coolant outlet 5. Among them, a heat pipe group 13 runs through between the coolant inlet 8 and the coolant outlet 5.

[0037] Regarding the insulating plate 2, the insulating plate 2 is usually composed of polymer materials (the materials are not limited) such as polyphenylene sulfide (PPS), polyurethane (PU), and poly-1,9-nonamethylene terephthalamide (PA9T).

[0038] Regarding the current collector plate 3, the current collector plate 3 is usually composed of highly conductive metals such as copper and silver, and a precious metal coating is plated on the surface to increase the durability of the current collector plate 3 and reduce the contact resistance between the current collector plate 3 and the core. Among them, the cooling medium of the external cooling circuit of the fuel cell stack (when operating at a temperature above zero, the cooling medium can be water) flows through the coolant inlet 8 through the intake end plate 1, enters the coolant inlet 8 of the insulating plate 2, and then enters the stack cells through the coolant inlet 8 of the current collector plate 3. After exchanging heat with the stack cells, the cooling medium passes through the coolant outlet 5 of the current collector plate 3, then through the coolant outlet 5 of the insulating plate 2, and enters the external cooling circuit of the fuel cell stack from the coolant outlet 5, and the cooling circuit is used to dissipate heat from the high-temperature cooling medium.

[0039] Regarding the heat pipe, see Figure 3 and Figure 4 , Figure 4It is a sectional view taken from the center of a heat pipe (including a heat pipe evaporation section 11 and a heat pipe condensation section 12). The heat pipe evaporation section 11 of the heat pipe is located in the coolant outlet 5 of the fuel cell stack and is in direct contact with the high-temperature cooling medium flowing through the coolant outlet 5. The heat pipe condensation section 12 of the heat pipe is in the coolant inlet 8 of the fuel cell stack and is in direct contact with the low-temperature cooling medium flowing through the coolant inlet 8. The heat pipe is a heat transfer element with a thermal conductivity far exceeding that of metals. It utilizes the principle of heat conduction and the rapid heat transfer of the phase change medium. When the temperature of the coolant contacted by the heat pipe evaporation section 11 exceeds the evaporation temperature of the heat pipe and the temperature of the coolant contacted by the heat pipe condensation section 12 is lower than the evaporation temperature of the heat pipe, the heat pipe evaporation section 11 absorbs the heat of the relatively high-temperature cooling medium it contacts to form hot steam, and transfers the heat of the high-temperature cooling medium in the coolant outlet 5 to the heat pipe condensation section 12 at the coolant inlet 8 quickly through the hot steam. The heat pipe condensation section 12 then transfers this heat to the low-temperature cooling medium at the coolant inlet 8 to increase the temperature of the low-temperature cooling medium at the coolant inlet 8.

[0040] As can be seen from the above solution, in this application, a heat pipe group 13 is provided in the fuel cell stack. The heat pipe group 13 includes at least one heat pipe. The heat pipe evaporation section 11 of the heat pipe is located in the coolant outlet 5 of the fuel cell stack, and the heat pipe condensation section 12 of the heat pipe is located in the coolant inlet 8 of the fuel cell stack. When the temperature of the cooling medium at the coolant outlet 5 is greater than the evaporation temperature of the heat pipe, the heat pipe transfers the heat of the high-temperature coolant at the coolant outlet 5 to the coolant inlet 8 to exchange heat with the low-temperature cooling medium at the coolant inlet 8, so as to increase the temperature of the cooling medium at the coolant inlet 8, and further reduce the temperature difference between the coolant outlet 5 and the coolant inlet 8.

[0041] In such Figure 5 ( Figure 5 In the specific example shown in the structural schematic diagram of the cooling circuit of the fuel cell stack installed with heat pipes (for the convenience of display, the heat pipes are uniformly shown on the cooling circuit outside the fuel cell stack)), the cooling circuit of the fuel cell stack mainly consists of components such as a coolant pump, a thermostat, a radiator, and temperature sensors (T1 and T2). The temperature sensor T1 is used to detect the temperature of the cooling medium at the coolant inlet, and the temperature sensor T2 is used to detect the temperature of the cooling medium at the coolant outlet. The cooling circuit is used to cool the fuel cell (the fuel cell stack is equivalent to a "fuel cell group"). During processes such as low-temperature startup and cold-state loading of the fuel cell, by closing the thermostat, the coolant is bypassed from the radiator, reducing the heat dissipation and accelerating the temperature rise of the stack; during the cooling process, by controlling the opening degree of the thermostat, the coolant flows through the radiator, increasing the heat dissipation and reducing the temperature of the stack. Thus, it can be seen that this solution can further improve the temperature management ability of the fuel cell stack by using heat pipes.

[0042] In this embodiment, the shapes of the heat pipe evaporation section 11 and the heat pipe condensation section 12, and their heat exchange modes with the coolant can be selected according to design requirements. For example, in this embodiment, the coolant and the heat pipe evaporation section 11 and the heat pipe condensation section 12 of the heat pipe can perform heat exchange through fins or winding.

[0043] The evaporation temperature of the heat pipes in the heat pipe group 13 can be set according to actual needs. When the target working condition is a low-temperature start-up working condition, the heat pipe group 13 can include heat pipes used in the low-temperature start-up working condition. In this embodiment, this heat pipe is denoted as the first heat pipe. The evaporation temperature of the first heat pipe is not lower than the preset low-temperature start-up temperature and not higher than the first upper limit temperature. The first upper limit temperature is the lowest temperature of the coolant outlet 5 of the fuel cell whose fuel cell stack is successfully started at low temperature and is pre-marked. For example, let the evaporation temperature of the first heat pipe be T1, satisfying T0 ≤ T1 ≤ T in_1 , where T0 is the preset low-temperature start-up temperature, usually -40~0°C, T in_1is the first upper limit temperature, and the first temperature upper limit is used to mark the lowest temperature of the coolant outlet 5 of the fuel cell stack with successful low-temperature startup. Its specific value can be determined during the fuel cell stack development test. In this embodiment, by measuring the temperature of the coolant after it rotates one week around the electric stack cooling circuit at the coolant outlet 5 when the low-temperature startup is successful, this temperature is determined as the first upper limit temperature. That is, the temperature corresponding to the moment when the temperature of the coolant at the coolant outlet 5 of the electric stack rises again after the first decrease when the low-temperature startup is successful is recorded as the first upper limit temperature. During the low-temperature startup process of the fuel cell stack, the control system of the fuel cell stack monitors the temperature of the fuel cell stack in real time. The temperature of the fuel cell stack can be obtained by identifying the temperature of the air outlet 4 (applicable to the case where the coolant flows in the same direction) or by theoretically calculating the heat generation through real-time acquisition of I-V data. When it is detected that the temperature of the fuel cell stack reaches T4 (T4 is a preset value within the range of [proton exchange membrane tolerance temperature - 30 - 30, proton exchange membrane tolerance temperature - 30 - 20] °C), the coolant pump starts to rotate. The specific process analysis is as follows: During the low-temperature startup process of the fuel cell stack, when loading current, the coolant pump has not rotated yet, and at this time, the coolant flow rate is zero. Therefore, both the temperature of the coolant outlet 5 and the temperature of the coolant inlet 8 are -30 °C; during the low-temperature startup process, the temperature of the air outlet of the fuel cell stack is monitored in real time. When the temperature of the air outlet of the fuel cell stack reaches T4, the coolant pump starts to work; when the temperature of the coolant outlet 5 reaches the evaporation temperature T1, the heat pipe evaporation section 11 of the first heat pipe in the coolant outlet 5 starts to absorb the heat of the high-temperature coolant in the coolant outlet 5 until the medium in the first heat pipe evaporates. The hot steam generated due to the evaporation of the medium in the first heat pipe diffuses along the first heat pipe to the heat pipe condensation section 12 of the first heat pipe. Since the heat pipe condensation section 12 is in contact with the low-temperature coolant in the coolant inlet 8 and the temperature of the heat pipe condensation section 12 is relatively low, at this time, the hot steam in the first heat pipe will condense and release heat at the heat pipe condensation section 12, and the released heat will be transferred to the low-temperature coolant in the coolant inlet 8, causing the temperature of the low-temperature coolant to rise. When the temperature of the coolant inlet 8 exceeds T1, the hot steam in the heat pipe will not condense at the coolant inlet 8, and at this time, the first heat pipe no longer participates in the work. In this process, as Figure 6 shown, during the control process of the fuel cell stack starting at -30 °C, the temperature change curve diagram of the cooling medium at the coolant outlet 5 and the coolant inlet 8, Figure 6 where the coolant outlet temperature is the temperature of the cooling medium at the coolant outlet, the coolant inlet temperature is the temperature of the cooling medium at the coolant inlet, and the current is the output current of the fuel cell stack.

[0044] When the target operating condition is the cold-state pulling load condition, the heat pipe group 13 may further include heat pipes used in the cold-state pulling load condition. In this embodiment, this heat pipe is denoted as the second heat pipe. The evaporation temperature T2 of the second heat pipe is higher than the first upper limit temperature T1 and not higher than the second upper limit temperature, where the second upper limit temperature is not higher than the thermostat opening temperature. In this embodiment, when the fuel cell stack completes low-temperature startup in a sub-zero environment, the temperature of the coolant in the large-circulation loop of the radiator in the coolant cooling loop of the stack is still below zero at this time. When the temperature of the coolant at the outlet 5 exceeds a certain value (the thermostat opening temperature), the control system will open the thermostat. At this time, the high-temperature coolant will enter the large-circulation loop of the radiator circuit and mix with the low-temperature (close to the ambient temperature) coolant in the large-circulation loop of the radiator and then enter the fuel cell stack. Since the temperature of the coolant becomes lower after the low-temperature coolant in the large-circulation loop of the radiator and the high-temperature coolant in the small cooling loop are mixed, such as between 10°C and 40°C. At this time, due to the slow evaporation rate and diffusion rate of water, the product water of the electrochemical reaction cannot be discharged in time and is likely to accumulate inside the porous medium of the membrane electrode, causing waterlogging, triggering voltage fluctuations, and reducing reliability. Since the fuel cell stack structure proposed in the present invention contains a second heat pipe, the evaporation temperature of the second heat pipe is set to T2. Such a setting can quickly increase the temperature of the mixed cooling medium after cutting into the large-circulation loop of the radiator, reduce the waterlogging phenomenon, and prevent voltage fluctuations. The specific process analysis is as follows: After the low-temperature startup is completed, the temperature of the coolant at the inlet 8 and the outlet 5 of the fuel cell stack is relatively high at this time. If the temperature of the coolant at the outlet 5 continues to rise, the control system controls to open the thermostat, and a part of the coolant is discharged from the outlet 5 of the coolant and then enters the large cooling loop of the radiator circuit; after the high-temperature coolant at the outlet 5 of the coolant and the low-temperature coolant in the large cooling loop of the radiator circuit are mixed, the temperature becomes lower, and the mixed cooling medium exchanges heat with the condensation section of the second heat pipe, making the temperature of the condensation section lower than T2. Since at this time, the temperature of the coolant at the outlet 5 of the coolant is greater than T2, and the temperature of the coolant at the inlet 8 of the coolant is less than T2, the second heat pipe starts to work at this time, and the heat of the coolant at the outlet 5 of the coolant is transferred to the coolant at the inlet 8 of the coolant through the second heat pipe to increase the temperature of the mixed cooling medium at the inlet 8 of the coolant. Figure 7 It is a graph showing the temperature change of the cooling medium at the coolant outlet 5 and the coolant inlet 8 during the cold-state pulling load process of the fuel cell stack. Among them, the dotted line corresponding to the coolant outlet temperature 2 is the temperature of the coolant at the outlet 5 before the second heat pipe is set, the dotted line corresponding to the coolant inlet temperature 2 is the temperature of the coolant at the inlet 8 before the second heat pipe is set, the solid line corresponding to the coolant outlet temperature 1 is the temperature of the coolant at the outlet 5 after the second heat pipe is set, and the solid line corresponding to the coolant inlet temperature 1 is the temperature of the coolant at the inlet 8 after the second heat pipe is set.

[0045] When the target working condition is the shutdown purging condition, the heat pipe group 13 may further include heat pipes used in the shutdown purging condition. In this embodiment, this heat pipe is denoted as the third heat pipe. The evaporation temperature of the third heat pipe is kept consistent with the third temperature, and the third temperature is not lower than the lower limit temperature of the purging recommendation and not higher than the upper limit temperature of the purging recommendation. The difference from the purging temperature of the fuel cell stack is less than the first preset value. For example, the first preset value can be 10°C. Preferably, the evaporation temperature of the third heat pipe is equal to the purging temperature. When the fuel cell starts in an environment below zero, it is required that the water content in the fuel cell stack is relatively low before startup. Therefore, in this environment, shutdown purging is a necessary step after the fuel cell system shuts down. In order to fully dry the fuel cell stack and reduce the purging time, it is usually required that the temperature of the fuel cell stack be maintained at a relatively high level, 50 - 70°C, during the cold purging period, where 50°C is the lower limit temperature of the purging recommendation and 70°C is the upper limit temperature of the purging recommendation. In this embodiment, the evaporation temperature of the third heat pipe is taken as 60°C. Since there is a heat exchange process between the external cooling circuit of the fuel cell stack and the sub-zero environment in the sub-zero environment, the temperature of the coolant flowing out from the coolant outlet 5 will drop significantly after flowing through the cooling circuit, making the temperature of the purged area unable to be maintained within a relatively high temperature range. In order to improve the temperature drop of the coolant flowing through the external cooling circuit of the stack during the cold purging process, the temperature of the third heat pipe is set to the purging target temperature. When the fuel cell stack enters the shutdown purging stage, if the temperature of the coolant outlet 5 is higher than T3 and the temperature of the coolant inlet 8 is lower than T3, the third heat pipe starts to work, transferring the heat of the high-temperature coolant at the coolant outlet 5 to the coolant at the coolant inlet 8, further increasing the temperature of the coolant at the coolant inlet 8, so as to ensure that the temperature of the fuel cell stack is maintained at a relatively high level during the cold purging period, thereby accelerating the drying speed of the membrane electrode and further reducing the purging time. It should be noted that during this process, since some heat is directly transferred through the third heat pipe, the heat of the cooling medium transferred by the cooling circuit is reduced, resulting in a decrease in the heat dissipation of the cooling circuit, and ultimately causing the temperature drop rate of the cooling medium at the coolant outlet 5 to slow down. Figure 8 It is a temperature change curve graph of the cooling medium at the coolant outlet 5 and the coolant inlet 8 during the purging process of the fuel cell stack. Among them, the coolant outlet temperature 1 and the coolant inlet temperature 1 corresponding to the thin dotted line respectively represent the temperature curves of the coolant outlet 5 and the coolant inlet 8 before the third heat pipe is set, and the coolant outlet temperature 2 and the coolant inlet temperature 2 corresponding to the thick dotted line respectively represent the temperature curves of the coolant outlet 5 and the coolant inlet 8 after the third heat pipe is set.

[0046] In this embodiment, as Figure 9 shown, the heat pipe group 13 may include a first heat pipe, a second heat pipe, and a third heat pipe, where Figure 9The heat pipe 1 therein represents the first heat pipe, the heat pipe 2 represents the second heat pipe, and the heat pipe 3 represents the third heat pipe. At this time, when the fuel cell stack starts up at a low temperature below zero degrees Celsius, the first heat pipe comes into play; when the fuel cell stack is cold-loaded, the second heat pipe comes into play; when the fuel cell stack is purged during shutdown, the third heat pipe comes into play. When the fuel cell stack reaches the normal operating temperature, since the temperature of the cooling medium at the coolant circuit is higher than the highest evaporation temperature among the three, the first heat pipe, the second heat pipe, and the third heat pipe all do not work and do not affect the normal operation of the fuel cell stack.

[0047] In this embodiment, the positions of the respective heat pipes in the heat pipe group 13 can be selected according to design requirements. In this solution, the respective heat pipes in the heat pipe group 13 can be integrally connected in parallel in the intake assembly of the fuel cell stack. For example, the respective heat pipes in the heat pipe group 13 can be arranged on the intake end plate 1 of the fuel cell stack, on the insulating plate 2 of the fuel cell stack, on the current collector plate 3 of the fuel cell stack, at the interface between the gas end plate and the insulating plate 2, and at the interface between the insulating plate 2 and the current collector plate 3. Of course, the respective heat pipes can also be arranged on the cooling circuit outside the fuel cell stack. The installation positions of the respective heat pipes can be the same or different. To facilitate the installation of the heat pipes on the intake end plate 1, the insulating plate 2, and the current collector plate 3, through-hole structures for the heat pipes to pass through can be provided on the gas end plate, the insulating plate 2, and the current collector plate 3. To facilitate the installation of the heat pipes at the interface between the gas end plate and the insulating plate 2 or at the interface between the insulating plate 2 and the current collector plate 3, grooves matching the shape of the heat pipes are provided on the intake end plate 1, the insulating plate 2, and the current collector plate 3.

[0048] From the above various embodiments, it can be seen that for the fuel cell stack disclosed in the present invention, since high-thermal-conductivity heat pipes are utilized in the intake assembly of the fuel cell stack, the heat of the high-temperature coolant at the coolant outlet 5 is rapidly transferred to the coolant inlet 8 under the target working conditions, thereby improving the phenomenon that the temperature of the coolant inlet 8 is relatively low and the temperature difference between the coolant inlet 8 and the coolant outlet 5 is relatively large under the target working conditions, reducing the heat dissipation of the external circulation of the fuel cell stack at the coolant outlet 5 under the target working conditions, and improving the reliability and dynamic response of the operation of the fuel cell system.

[0049] Corresponding to the above fuel cell stack, the present application also discloses a fuel cell engine, which may include any one of the above fuel cell stacks.

[0050] A vehicle includes the above fuel cell engine.

[0051] For the convenience of description, when describing the above system, it is divided into various modules according to functions and described separately. Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments. The system and system embodiments described above are only illustrative. Users can select some or all of the modules according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0052] It should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent in such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0053] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fuel cell stack, characterized in that, Comprising: A heat pipe group, the heat pipe group includes at least one heat pipe, the heat pipe evaporation sections of the heat pipes in the heat pipe group are located at the coolant outlet of the fuel cell stack, and the condensation sections of the heat pipes are located at the coolant inlet of the fuel cell stack; The heat pipes are heat pipes operating under target conditions, and the target conditions include at least one of a low-temperature start-up condition, a cold-state pull-load condition, and a shutdown purge condition.

2. The fuel cell stack according to claim 1, characterized in that, When the target condition is a low-temperature start-up condition, the heat pipe group includes a first heat pipe; The evaporation temperature of the first heat pipe is not lower than a preset low-temperature start-up temperature and not higher than a first upper limit temperature, and the first upper limit temperature is the lowest coolant outlet temperature of the fuel cell stack with the fuel cell stack having a successful low-temperature start-up marked in advance.

3. The fuel cell stack according to claim 1, characterized in that, When the target condition is a cold-state pull-load condition, the heat pipe group includes a second heat pipe; The evaporation temperature of the second heat pipe is higher than the first upper limit temperature and not higher than a second upper limit temperature, and the second upper limit temperature is not higher than the thermostat opening temperature, and the first upper limit temperature is the lowest coolant outlet temperature of the fuel cell stack with the fuel cell stack having a successful low-temperature start-up marked in advance.

4. The fuel cell stack according to claim 1, wherein, When the target condition is a shutdown purge condition, the heat pipe group includes a third heat pipe; The evaporation temperature of the third heat pipe is consistent with a third temperature, and the third temperature is not lower than a purge recommended lower limit temperature and not higher than a purge recommended upper limit temperature.

5. The fuel cell stack according to claim 1, characterized in that, The heat pipes in the heat pipe group are integrally connected in parallel in the intake assembly of the fuel cell stack.

6. The fuel cell stack according to claim 5, characterized in that, The heat pipes in the heat pipe group are arranged on the intake end plate of the fuel cell stack, on the insulating plate of the fuel cell stack, on the current collector plate of the fuel cell stack, at the interface between the intake end plate and the insulating plate, at the interface between the insulating plate and the current collector plate, or on the cooling circuit outside the fuel cell stack.

7. The fuel cell stack according to claim 6, characterized in that, Grooves or through holes matching the shape of the heat pipes are provided on the intake end plate, insulating plate, or current collector plate of the fuel cell stack.

8. A fuel cell engine, characterized in that, A fuel cell stack according to any one of claims 1-7.

9. A vehicle, characterized in that, A fuel cell engine according to claim 8.

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