Device and method for adjusting inlet air humidity of fuel cell by using liquid hydrogen cold energy

Abstract

The invention discloses a device and a method for adjusting air inlet humidity of a fuel cell by using liquid hydrogen cold energy. The device comprises a liquid hydrogen tank, a liquid hydrogen vaporizer, a pressure reducing valve, an ejector and a steam-water separator. By adding a cooling loop of a steam-water separator and a shunting pipeline of a galvanic pile cooling liquid, part of cold energy of liquid hydrogen is transferred to backflow hydrogen in the steam-water separator through the galvanic pile cooling liquid, so that the humidity and temperature of the backflow hydrogen are controlled, and liquid water brought into a galvanic pile is reduced; meanwhile, the temperature difference between the backflow hydrogen and the new hydrogen can be controlled, liquid water is prevented from being generated due to the too large temperature difference when the backflow hydrogen and the new hydrogen are mixed in the ejector, and the liquid water is prevented from flowing into a galvanic pile to cause local water accumulation. The hydrogen temperature adjusting device is simple in design structure, cold energy of liquid hydrogen can be fully utilized while hydrogen temperature adjustment is achieved, and system energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular, to a device and method for regulating the intake humidity of a fuel cell by utilizing the cold energy of liquid hydrogen. Background Art

[0002] Currently, in a fuel cell system, the tail gas generated by the stack usually contains a part of hydrogen and water vapor. In order to make full use of this part of hydrogen, a steam-water separator is generally used to separate the liquid water in the tail gas discharged from the anode of the stack, and then the unreacted hydrogen enters the circulation device and is mixed with the hydrogen provided by the hydrogen supply device, and then enters the stack to be reused.

[0003] Regarding the design of hydrogen reflux and hydrogen mixing, the prior art generally adopts the following scheme: the reflux hydrogen (the hydrogen that will be separated by the steam-water separator and reused after being discharged from the anode outlet of the stack) is separated by the steam-water separator to reduce the liquid water in the reflux hydrogen, and then the ejector ejects the separated reflux hydrogen. In the mixing section of the ejector, the fresh hydrogen (the hydrogen after vaporization of the liquid hydrogen in the hydrogen supply device) is mixed with the reflux hydrogen, and the mixed hydrogen enters the stack, so as to achieve the purpose of reusing the reflux hydrogen. However, in this scheme, due to the large temperature difference between the reflux hydrogen and the fresh hydrogen, liquid water is likely to appear in the mixing section of the ejector, and the liquid water enters the stack under the push of the air flow, resulting in water accumulation in the stack, which is not conducive to the working performance of the stack. At the same time, the existing steam-water separator cannot effectively regulate the humidity and temperature of the fresh hydrogen and the reflux hydrogen, and cannot meet the requirements of the stack for the temperature and humidity of hydrogen under different working conditions. Summary of the Invention

[0004] Aiming at the above technical problems, the present invention aims to provide a device and method for regulating the intake humidity of a fuel cell by utilizing the cold energy of liquid hydrogen, which can not only reduce the temperature difference between the reflux hydrogen and the fresh hydrogen, avoid the appearance of more liquid water in the mixing section, but also has a simple design, can realize the full utilization of the cold energy of liquid hydrogen, reduce the system energy consumption, the adjustable and controllable intake humidity of hydrogen, and significantly improve the separation efficiency of the steam-water separator.

[0005] The technical solution adopted by the present invention to solve its technical problems is:

[0006] An apparatus for regulating the intake humidity of a fuel cell using the cold energy of liquid hydrogen, comprising a liquid hydrogen tank, a liquid hydrogen vaporizer, a pressure reducing valve, an ejector and a steam-water separator, characterized in that the hydrogen and water vapor discharged from the fuel cell stack enter through a hydrogen return pipeline from the steam-water separator inlet of the steam-water separator, and then flow out from the steam-water separator outlet after passing through the gas flow channel of the steam-water separator; the returned hydrogen separated by the steam-water separator then enters the ejector; the coolant for cooling the fuel cell stack is split into two parts by an electronic three-way valve at the coolant outlet of the fuel cell stack, one part of the coolant returns to the fuel cell stack through a pipeline after passing through a radiator, and the other part of the coolant flows through a pipeline to the liquid hydrogen vaporizer to perform cold energy heat exchange with the liquid hydrogen coming out of the liquid hydrogen tank; an electronic three-way valve is provided at the coolant outlet of the liquid hydrogen vaporizer, and the electronic three-way valve splits the coolant at the outlet of the liquid hydrogen vaporizer into two parts of coolant that has absorbed cold energy; one part of the coolant that has absorbed cold energy enters from the coolant inlet of the steam-water separator, flows through the cooling baffle of the steam-water separator and the coolant flow channel of the steam-water separator, and then flows out from the coolant outlet of the steam-water separator, and the other part of the coolant that has absorbed cold energy does not flow through the steam-water separator, and after this part of the coolant converges with the coolant flowing out from the coolant outlet of the steam-water separator, it returns to the fuel cell stack to play a role in cooling and temperature reduction; the liquid hydrogen after heat exchange flows out of the pressure reducing valve and then enters the ejector; in the ejector, the fresh hydrogen passing through the pressure reducing valve is mixed with the returned hydrogen separated by the steam-water separator and is supplied to the anode of the fuel cell stack through a hydrogen supply pipeline.

[0007] Further, the coolant in the cooling baffle of the steam-water separator and the coolant flow channel of the steam-water separator exchanges heat with the returned hydrogen in the gas flow channel of the steam-water separator.

[0008] Further, a temperature sensor is provided on the pipeline from the outlet of the pressure reducing valve to the ejector, and this temperature sensor controls the opening degree of the electronic three-way valve at the coolant outlet of the fuel cell stack; another temperature sensor is provided on the pipeline from the outlet of the steam-water separator to the ejector, and after comparing the temperature values of the two temperature sensors, the opening degree of the electronic three-way valve at the coolant outlet of the liquid hydrogen vaporizer is controlled.

[0009] Further, a humidity sensor is provided on the pipeline from the outlet of the ejector to the anode inlet of the fuel cell stack, and after comparing the humidity, the opening degrees of the two electronic three-way valves are controlled.

[0010] Further, the coolant flow channel of the steam-water separator is provided on the outer wall of the steam-water separator.

[0011] Further, a steam-water separator drain port is provided below the steam-water separator.

[0012] The second object of the present invention is to provide a method for regulating the intake humidity of a fuel cell using the cold energy of liquid hydrogen, and the method specifically includes the following steps:

[0013] S1. The hydrogen and water vapor discharged from the stack enter the steam separator through the hydrogen return pipeline. The coolant used to cool the stack is split into two parts at the outlet of the stack. One part flows through the pipeline to the radiator and then returns to the stack, and the other part flows through the pipeline to the liquid hydrogen vaporizer for heat exchange with liquid hydrogen. The coolant after heat exchange then enters the steam separator for heat exchange with the mixed gas in the hydrogen return pipeline to control the temperature and humidity of the mixed gas through the heat exchange process. The returned hydrogen obtained by the mixed gas through heat exchange in the steam separator enters the ejector.

[0014] S2. After the liquid hydrogen exchanges heat with the coolant in the liquid hydrogen vaporizer, it flows through the pressure reducing valve and then to the ejector. After mixing with the returned hydrogen that has undergone heat exchange and steam separation in the ejector, it is supplied to the anode of the stack.

[0015] S3. The coolant after heat exchange in the steam separator returns to the stack.

[0016] S4. According to the target humidity value of the hydrogen intake of the stack, the temperature limit of the fresh hydrogen intake of the ejector, and the maximum temperature difference limit between the fresh hydrogen and the returned hydrogen, the coolant flow rates flowing to the liquid hydrogen vaporizer and the steam separator are controlled so that the humidity of the hydrogen intake of the stack and the temperature difference between the fresh hydrogen and the returned hydrogen reach the target limits.

[0017] Further, the control steps for the coolant flow rate in step S4 are as follows:

[0018] S4.1. There is a temperature sensor 5 on the fresh hydrogen supply pipeline flowing from the pressure reducing valve to the ejector. When the monitored temperature T5 of the temperature sensor is less than the minimum intake temperature limit T min of the ejector, the opening degree of the electronic three-way valve 11 at the outlet of the stack coolant is adjusted to increase the flow rate of the coolant at the stack outlet flowing to the liquid hydrogen vaporizer. When the monitored temperature T5 of the temperature sensor is greater than the maximum intake temperature limit T max of the ejector, the opening degree of the electronic three-way valve 11 at the outlet of the stack coolant is adjusted to reduce the flow rate of the coolant at the stack outlet flowing to the liquid hydrogen vaporizer.

[0019] S4.2. There is a temperature sensor 2 on the pipeline from the outlet of the steam separator to the ejector. The temperature difference |T5 - T2| between the monitored temperature T5 of the temperature sensor 5 and the monitored temperature T2 of the temperature sensor 2, the maximum temperature difference limit T diff between the fresh hydrogen and the returned hydrogen, and there is an electronic three-way valve 9 on the pipeline from the outlet of the liquid hydrogen vaporizer coolant to the steam separator. The opening degree of the electronic three-way valve 9 is controlled through the following relationship:

[0020] S4.2.1. When |T5 - T2| > T diff , the opening degree of the electronic three-way valve 9 is adjusted to increase the flow rate of the coolant at the outlet of the liquid hydrogen vaporizer flowing to the steam separator.

[0021] S4.2.2. When |T5 - T2| ≤ T diff perform adjustment according to the humidity of the hydrogen intake of the stack in step S4.3.

[0022] S4.3. For the humidity value RH3 of the humidity sensor 3 on the pipeline from the ejector outlet to the anode of the stack, and the target humidity value RH of the hydrogen intake of the stack t control the opening degrees of the electronic three-way valve 9 and the electronic three-way valve 11 through the following relationship;

[0023] S4.3.1. When RH3 < RH t first adjust the opening degree of the electronic three-way valve 9 to reduce the flow rate of the coolant at the outlet of the liquid hydrogen vaporizer flowing to the steam-water separator. On the premise of satisfying |T5 - T2| ≤ T diff if RH3 = RH t can be achieved, then maintain the opening degrees of the electronic three-way valves 9 and 11, and the system operates normally; if RH3 = RH t cannot be achieved, then adjust the opening degree of the electronic three-way valve 11 to reduce the flow rate of the coolant at the stack outlet flowing to the liquid hydrogen vaporizer until RH3 = RH t can be achieved;

[0024] S4.3.2. When RH3 > RH t first adjust the opening degree of the electronic three-way valve 9 to increase the flow rate of the coolant at the outlet of the liquid hydrogen vaporizer flowing to the steam-water separator. On the premise of satisfying |T5 - T2| ≤ T diff if RH3 = RH t can be achieved, then maintain the opening degrees of the electronic three-way valves 9 and 11, and the system operates normally; if RH3 = RH t cannot be achieved, then adjust the opening degree of the electronic three-way valve 11 to increase the flow rate of the coolant at the stack outlet flowing to the liquid hydrogen vaporizer until RH3 = RH t can be achieved;

[0025] S4.3.3. When RH3 = RH t then maintain the opening degrees of the electronic three-way valves 9 and 11, and the system operates normally.

[0026] When the system of the present invention operates, first, part of the coolant exchanges heat with liquid hydrogen. While heating and raising the temperature of the liquid hydrogen, it absorbs part of the cold energy. Then, the heat-exchanged coolant exchanges heat with the mixed gas of hydrogen and water vapor discharged from the fuel cell stack. On the one hand, by controlling the temperature, the temperature of the mixed gas can be changed, reducing the temperature difference between the mixed gas and the fresh hydrogen, preventing excessive liquid water from being generated during the mixing stage of the ejector due to too large a difference between the two. On the other hand, by changing the absolute temperature of the mixed gas, liquid water can be formed in the steam-water separator, reducing the humidity of the mixed gas and preventing too much water vapor from being introduced into the fuel cell stack.

[0027] The present invention has the following technical effects:

[0028] 1. The present invention only needs to add a cooling circuit for the steam-water separator and a shunt pipeline for the coolant in the existing system solution. By controlling the utilization amount of the cold energy of liquid hydrogen, the regulation and control of the humidity and temperature of the hydrogen intake can be achieved, and the system structure is simple.

[0029] 2. While using the cold energy of liquid hydrogen to control the humidity and temperature of the hydrogen intake, the present invention also reduces the temperature of the coolant, and at the same time reduces the coolant flow rate flowing to the radiator, reducing the load of the subsequent radiator and achieving energy saving of the system.

[0030] 3. Through the heat exchange between the coolant and liquid hydrogen and the recycled hydrogen, the temperature difference between the liquid hydrogen and the recycled hydrogen is reduced, making the temperature of the recycled hydrogen after passing through the steam-water separator close to that of the fresh hydrogen, avoiding the occurrence of liquid water in the mixing section of the ejector due to too large a temperature difference between the two, and thus preventing water accumulation in the subsequent fuel cell stack. Description of the Drawings

[0031] Referring to the accompanying drawings, the disclosure of the present invention will become more understandable. It is easy for those skilled in the art to understand that these drawings are only used to illustrate the technical solutions of the present invention and are not intended to limit the protection scope of the present invention.

[0032] Figure 1 Schematic diagram of the structure of a fuel cell for regulating the intake humidity by using the cold energy of liquid hydrogen according to a preferred embodiment of the present invention;

[0033] Figure 2 Schematic diagram of the structure of the steam-water separator in the schematic diagram of the structure of a fuel cell for regulating the intake humidity by using the cold energy of liquid hydrogen according to the preferred embodiment of the present invention;

[0034] Figure 3 Flow chart of the method for regulating the intake humidity of a fuel cell by using the cold energy of liquid hydrogen according to the present invention.

[0035] The reference numerals in each figure are as follows: 1 - fuel cell stack; 2 - temperature sensor; 3 - humidity sensor; 4 - ejector; 5 - temperature sensor; 6 - pressure reducing valve; 7 - liquid hydrogen vaporizer; 8 - liquid hydrogen tank; 9 - electronic three-way valve; 10 - steam-water separator; 11 - electronic three-way valve; 12 - radiator; 13 - cooling fan; 14 - water pump; 15 - hydrogen return pipeline; 16 - steam-water separator inlet; 17 - steam-water separator outlet; 18 - steam-water separator coolant inlet; 19 - steam-water separator coolant outlet; 20 - steam-water separator drain outlet; 21 - steam-water separator cooling baffle; 22 - steam-water separator coolant flow channel; 23 - steam-water separator gas flow channel. Detailed implementation manners

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative work shall fall within the protection scope of the present invention.

[0037] As Figure 1 and Figure 2 shown are a structural schematic diagram of a fuel cell for regulating intake humidity by using the cold energy of liquid hydrogen and a structural diagram of a steam-water separator in a preferred embodiment of the present application. As Figure 1 and Figure 2As shown, the device for regulating the intake humidity of a fuel cell using the cold energy of liquid hydrogen includes a liquid hydrogen tank 8, a liquid hydrogen vaporizer 7, a pressure reducing valve 6, an ejector 4, and a steam-water separator 10. The hydrogen and water vapor discharged from the fuel cell stack 1 enter through the hydrogen return pipeline 15 from the steam-water separator inlet 16 of the steam-water separator 10, and then flow out from the steam-water separator outlet 17 after passing through the steam-water separator gas flow channel 23; the returned hydrogen separated by the steam-water separator 10 then enters the ejector 4; the coolant used to cool the fuel cell stack 1 is split into two parts by the electronic three-way valve 11 at the fuel cell coolant outlet. One part of the coolant flows through the pipeline to the radiator 12, and after being cooled by the radiator 12 and the cooling fan 13, it returns to the fuel cell stack. The other part of the coolant flows through the pipeline to the liquid hydrogen vaporizer 7, exchanges cold energy with the liquid hydrogen in the liquid hydrogen tank 8, and then is split into two parts of the coolant that has absorbed cold energy by the electronic three-way valve 9; one part of the coolant that has absorbed cold energy enters from the steam-water separator coolant inlet 18, flows through the steam-water separator cooling baffle 21 and the steam-water separator coolant flow channel 22, and then flows out from the steam-water separator coolant outlet 19. The other part of the coolant that has absorbed cold energy does not flow through the steam-water separator 10. After this part of the coolant converges with the coolant flowing out from the steam-water separator coolant outlet 19, it, together with the coolant at the outlet of the radiator 12, returns to the fuel cell stack under the action of the water pump 14 to play a role in cooling and temperature reduction; the hydrogen after heat exchange enters the ejector 4 after passing through the pressure reducing valve 6; in the ejector 4, the fresh hydrogen passing through the pressure reducing valve 6 is mixed with the returned hydrogen separated by the steam-water separator 10 and is supplied to the anode of the fuel cell stack 1 through the hydrogen supply pipeline.

[0038] In this embodiment, the coolant in the steam-water separator cooling baffle 21 and the steam-water separator coolant flow channel 22 exchanges heat with the returned hydrogen in the steam-water separator gas flow channel 23, and the temperature and humidity of the returned hydrogen can be controlled through heat exchange. The temperature of the hydrogen and water vapor discharged from the fuel cell stack is generally relatively high, and the hydrogen is generally in a supersaturated state. After encountering the relatively low-temperature coolant in the steam-water separator 10, more liquid water is likely to be generated, thereby reducing the humidity of the hydrogen and preventing excessive water vapor from being brought in when it is mixed with hydrogen in the subsequent ejector. In addition, after heat exchange in the steam-water separator 10, the temperature of the returned hydrogen will also decrease, and the temperature difference from the fresh hydrogen will also become smaller, which can avoid too large a temperature difference between the two, causing liquid water to be generated during the mixing stage of the hydrogen in the ejector 4. If the humidity in the returned hydrogen is too high, or the temperature difference between the returned hydrogen and the fresh hydrogen is too large, it is easy to increase the amount of liquid water entering the fuel cell stack 1, causing local flooding of the fuel cell stack 1 and thus affecting the performance of the fuel cell stack 1.

[0039] Further, a temperature sensor 2 is provided on the pipeline from the gas outlet 17 of the steam separator to the ejector 4, and a temperature sensor 5 is provided on the outlet pipeline of the pressure reducing valve 6. According to the comparison between the difference between the temperature sensors 5 and the target difference, the opening degree of the electronic three-way valve 11 can be controlled to realize the flow control of the coolant flowing out of the fuel cell stack to the liquid hydrogen vaporizer 7, so as to control the temperature of the coolant at the outlet of the liquid hydrogen vaporizer 7 and the temperature of the hydrogen gas at the outlet. According to the comparison between the difference between the temperature sensor 2 and the temperature sensor 5 and the target difference, the opening degree of the electronic three-way valve 9 can be controlled to realize the flow control of the coolant flowing to the steam separator 10, so as to control the temperature of the hydrogen gas flowing back at the outlet of the steam separator 10 and the temperature of the gas in the cavity, and further realize the control of the separation efficiency of the steam separator 10, and the temperature difference between the fresh hydrogen and the hydrogen gas flowing back can be controlled to prevent the generation of liquid water during the mixing stage of the ejector 4.

[0040] Further, a humidity sensor 3 is provided on the outlet pipeline of the ejector 4 to monitor the humidity of the mixture of the fresh hydrogen and the hydrogen gas flowing back. According to the comparison between the monitored value of the humidity sensor 3 and the target humidity, the opening degrees of the electronic three-way valve 11 and the electronic three-way valve 9 can be controlled, so that the humidity of the hydrogen gas flowing to the anode of the fuel cell stack reaches the target value.

[0041] Further, the coolant flow channel 22 of the steam separator is provided on the outer wall of the steam separator 10. This can prolong the heat exchange process between the coolant and the hydrogen gas flowing back, so as to ensure the stability of the temperature and humidity of the hydrogen gas flowing back, and can also separate more liquid water to prevent local flooding of the fuel cell stack 1.

[0042] Further, a steam separator drain port 20 is provided below the steam separator 10. The coolant in the steam separator cooling baffle 21 and the coolant flow channel 22 of the steam separator exchanges heat with the hydrogen gas flowing back in the steam separator gas flow channel 23, and the liquid water generated by the heat exchange is discharged from the steam separator drain port 20.

[0043] The method for regulating the intake humidity of a fuel cell using the cold energy of liquid hydrogen disclosed in the present invention includes the following steps:

[0044] S1, the hydrogen gas and water vapor discharged from the fuel cell stack 1 enter the steam separator 10 through the hydrogen gas return pipeline 15. The coolant used to cool the fuel cell stack 1 is split into two parts at the outlet of the fuel cell coolant. One part flows through the pipeline to the radiator 12 and then returns to the fuel cell stack 1, and the other part flows through the pipeline to the liquid hydrogen vaporizer 7 for heat exchange with liquid hydrogen. The coolant after heat exchange then enters the steam separator 10 for heat exchange with the mixed gas in the hydrogen gas return pipeline 15, and the temperature and humidity of the mixed gas are controlled through the heat exchange process; the hydrogen gas flowing back obtained by the mixed gas through heat exchange in the steam separator 10 enters the ejector 4;

[0045] S2. After the liquid hydrogen exchanges heat with the coolant in the liquid hydrogen vaporizer 7, it flows through the pressure reducing valve 6 and then to the ejector 4. After mixing with the recycled hydrogen gas passing through the steam-water separator 10 in the ejector 4, it is supplied to the anode of the fuel cell stack 1.

[0046] S3. The coolant that has undergone heat exchange in the steam-water separator 10 returns to the fuel cell stack.

[0047] S4. According to the target humidity value of the hydrogen intake of the fuel cell stack, the limit of the intake temperature of the fresh hydrogen of the ejector, and the maximum temperature difference limit between the fresh hydrogen and the recycled hydrogen, the flow rates of the coolant flowing to the liquid hydrogen vaporizer 7 and the steam-water separator 10 are controlled so that the humidity of the hydrogen intake of the fuel cell stack and the temperature difference between the fresh hydrogen and the recycled hydrogen reach the target limits.

[0048] As Figure 3 shown, in step S4 of the present invention, the specific steps for controlling the flow rate of the coolant are as follows:

[0049] S4.1. There is a temperature sensor 5 on the fresh hydrogen supply pipeline flowing from the pressure reducing valve 6 to the ejector 4. When the monitored temperature T5 of the temperature sensor 5 is less than the minimum intake temperature limit T min of the ejector 4, the opening of the electronic three-way valve 11 is adjusted to increase the flow rate of the coolant flowing from the outlet of the fuel cell stack to the liquid hydrogen vaporizer 7; when the monitored temperature T5 of the temperature sensor 5 is greater than the maximum intake temperature limit T max of the ejector 4, the opening of the electronic three-way valve 11 is adjusted to reduce the flow rate of the coolant flowing from the outlet of the fuel cell stack to the liquid hydrogen vaporizer 7.

[0050] S4.2. There is a temperature sensor 2 on the pipeline flowing from the outlet 17 of the steam-water separator to the ejector 4. The temperature difference |T5 - T2| between the monitored temperature T5 of the temperature sensor 5 and the monitored temperature T2 of the temperature sensor 2, and the maximum temperature difference limit T diff between the fresh hydrogen and the recycled hydrogen are used to control the opening of the electronic three-way valve 9 through the following relationship:

[0051] S4.2.1. When |T5 - T2| > T diff , the opening of the electronic three-way valve 9 is adjusted to increase the flow rate of the coolant flowing from the outlet of the liquid hydrogen vaporizer 7 to the steam-water separator 10.

[0052] S4.2.2. When |T5 - T2| ≤ T diff , step S4.3 is adjusted according to the humidity of the hydrogen intake of the fuel cell stack.

[0053] S4.3. The humidity value RH3 of the humidity sensor 3 on the pipeline from the outlet of the ejector 4 to the anode of the fuel cell stack, and the target humidity value RH t of the hydrogen intake of the fuel cell stack are used to control the opening of the electronic three-way valve 9 and the electronic three-way valve 11 through the following relationship;

[0054] S4.3.1. When RH3 < RH t At this time, first adjust the opening degree of the electronic three-way valve 9 to reduce the flow rate of the coolant flowing out of the liquid hydrogen vaporizer 7 to the steam-water separator 10. On the premise of satisfying |T5 - T2| ≤ T diff , if it can achieve RH3 = RH t , then maintain the opening degrees of the electronic three-way valves 9 and 11, and the system operates normally; if it cannot achieve RH3 = RH t , then adjust the opening degree of the electronic three-way valve 11 to reduce the flow rate of the coolant flowing out of the fuel cell stack to the liquid hydrogen vaporizer 7 until it can achieve RH3 = RH t ;

[0055] S4.3.2. When RH3 > RH t At this time, adjust the opening degree of the electronic three-way valve 9 to increase the flow rate of the water flowing out of the liquid hydrogen vaporizer to the steam-water separator 10. On the premise of satisfying |T5 - T2| ≤ T diff , if it can achieve RH3 = RH t , then maintain the opening degrees of the electronic three-way valves 9 and 11, and the system operates normally; if it cannot achieve RH3 = RH t , then start to adjust the opening degree of the electronic three-way valve 11 to increase the flow rate of the water flowing out of the fuel cell stack to the liquid hydrogen vaporizer 7 until it can achieve RH3 = RH t ;

[0056] S4.3.3. When RH3 = RH t , then maintain the opening degrees of the electronic three-way valves 9 and 11, and the system operates normally.

[0057] Furthermore, in step S3, the coolant that does not enter the steam-water separator 10 after being split by the electronic three-way valve 9 re-converges with the coolant at the coolant outlet 19 of the steam-water separator, and then returns to the fuel cell stack 1.

[0058] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, they can also make several substitutions or modifications to these described embodiments, and these substitution or modification methods should all be regarded as belonging to the protection scope of the present invention.

Claims

1. An apparatus for regulating the intake humidity of a fuel cell using the cold energy of liquid hydrogen, comprising a liquid hydrogen tank (8), a liquid hydrogen vaporizer (7), a pressure reducing valve (6), an ejector (4) and a steam-water separator (10), characterized in that, The hydrogen and water vapor discharged from the fuel cell stack (1) enter through the hydrogen return pipeline (15) from the intake port (16) of the steam separator (10) of the steam-water separator, and then flow out from the outlet (17) of the steam separator after passing through the gas flow channel (23) of the steam separator; the returned hydrogen separated by the steam separator (10) then enters the ejector (4); the coolant used to cool the fuel cell stack (1) is split into two parts by the electronic three-way valve (11) at the coolant outlet of the fuel cell stack. One part of the coolant flows through the pipeline through the radiator (12) and then returns to the fuel cell stack (1), and the other part of the coolant flows through the pipeline to the liquid hydrogen vaporizer (7), where it exchanges cold energy with the liquid hydrogen coming out of the liquid hydrogen tank (8). After that, the electronic three-way valve (9) splits it into two parts of the coolant that has absorbed cold energy; one part of the coolant that has absorbed cold energy enters from the coolant inlet (18) of the steam separator, flows through the cooling baffle (21) of the steam separator and the coolant flow channel (22) of the steam separator, and then flows out from the coolant outlet (19) of the steam separator. The other part of the coolant that has absorbed cold energy does not flow through the steam separator (10). After this part of the coolant merges with the coolant flowing out from the coolant outlet (19) of the steam separator, it returns to the fuel cell stack (1) again; the hydrogen after heat exchange flows out of the pressure reducing valve (6) and then enters the ejector (4); in the ejector (4), the fresh hydrogen passing through the pressure reducing valve (6) is mixed with the returned hydrogen separated by the steam separator (10) and is supplied to the anode of the fuel cell stack (1) through the hydrogen supply pipeline.

2. The device for regulating the intake humidity of a fuel cell by utilizing the cold energy of liquid hydrogen according to claim 1, wherein The coolant in the cooling baffle (21) of the steam separator and the coolant flow channel (22) of the steam separator exchanges heat with the returned hydrogen in the gas flow channel (23) of the steam separator.

3. A device for regulating the intake air humidity of a fuel cell by utilizing the cold energy of liquid hydrogen according to claim 1 or 2, characterized in that, A temperature sensor (2) is provided on the pipeline from the outlet (17) of the steam separator to the ejector (4), and a temperature sensor (5) is provided on the pipeline from the outlet of the pressure reducing valve (6) to the ejector (4). The temperature sensor (5) controls the opening degree of the electronic three-way valve (11), and the temperature sensors (2) and (5) control the opening degree of the electronic three-way valve (9) after comparing the temperature values.

4. A device for regulating the intake humidity of a fuel cell by utilizing the cold energy of liquid hydrogen according to claim 3, characterized in that, A humidity sensor (3) is provided on the pipeline from the outlet of the ejector (4) to the anode of the fuel cell stack (1), and the humidity sensor (3) controls the opening degrees of the electronic three-way valve (11) and the electronic three-way valve (9).

5. A device for regulating the intake humidity of a fuel cell by utilizing the cold energy of liquid hydrogen according to any one of claims 1-4, characterized in that, The coolant flow channel (22) of the steam separator is provided on the outer wall of the steam separator (10).

6. A device for regulating the intake humidity of a fuel cell by utilizing the cold energy of liquid hydrogen according to any one of claims 1-4, characterized in that, A drain port (20) of the steam separator is provided below the steam separator (10).

7. A method for regulating the intake humidity of a fuel cell by utilizing the cold energy of liquid hydrogen, characterized in that, Adjusting the intake humidity using the device according to any one of claims 1-6 includes the following steps: S1. The hydrogen and water vapor discharged from the stack (1) enter the steam separator (10) through the hydrogen return pipeline (15). The coolant used to cool the stack (1) is split into two parts at the stack coolant outlet. One part flows through the pipeline to the radiator (12) and then returns to the stack (1), and the other part flows through the pipeline to the liquid hydrogen vaporizer (7) for heat exchange with liquid hydrogen. The coolant after heat exchange partially enters the steam separator (10) for heat exchange with the mixed gas in the hydrogen return pipeline (15), and the temperature and humidity of the mixed gas are controlled through the heat exchange process. The return hydrogen obtained by heat exchange and separation of the mixed gas in the steam separator (10) enters the ejector (4). S2. After heat exchange with the coolant in the liquid hydrogen vaporizer (7), the liquid hydrogen flows through the pressure reducing valve (6) and then to the ejector (4). After mixing with the return hydrogen obtained by heat exchange and separation in the ejector (4), it is supplied to the anode of the stack (1). S3. The coolant after heat exchange in the steam separator (10) returns to the stack. S4. According to the target humidity value of the hydrogen intake of the stack, the new hydrogen intake temperature limit of the ejector, and the maximum temperature difference limit between the new hydrogen and the return hydrogen, the coolant flow rates flowing to the liquid hydrogen vaporizer (7) and the steam separator (10) are controlled so that the hydrogen intake humidity of the stack and the temperature difference between the new hydrogen and the return hydrogen reach the target limits.

8. A method for regulating the intake humidity of a fuel cell by utilizing the cold energy of liquid hydrogen according to claim 7, characterized in that, The control steps for the coolant flow rate in step S4 are as follows: S4.

1. There is a temperature sensor (5) on the fresh hydrogen supply pipeline flowing from the pressure reducing valve (6) to the ejector (4). When the monitored temperature T5 of the temperature sensor (5) is less than the minimum intake temperature limit T of the ejector (4), the opening of the electronic three-way valve (11) is adjusted to increase the coolant flow rate of the fuel cell stack coolant flowing to the liquid hydrogen vaporizer (7); when the monitored temperature T5 of the temperature sensor (5) is greater than the maximum intake temperature limit T of the ejector (4), the opening of the electronic three-way valve (11) is adjusted to reduce the coolant flow rate of the fuel cell stack coolant flowing to the liquid hydrogen vaporizer (7); min When, the opening of the electronic three-way valve (11) is adjusted to increase the coolant flow rate of the fuel cell stack coolant flowing to the liquid hydrogen vaporizer (7); when the monitored temperature T5 of the temperature sensor (5) is greater than the maximum intake temperature limit T of the ejector (4), max the opening of the electronic three-way valve (11) is adjusted to reduce the coolant flow rate of the fuel cell stack coolant flowing to the liquid hydrogen vaporizer (7); S4.

2. A temperature sensor (2) is provided on the pipeline from the outlet of the steam separator (17) to the ejector (4). The temperature difference |T5 - T2| between the monitored temperature T5 of the temperature sensor (5) and the monitored temperature T2 of the temperature sensor (2), and the maximum temperature difference limit T between the fresh hydrogen and the reflux hydrogen diff , and the opening of the electronic three-way valve (9) is controlled through the following relationship: S4.2.

1. When |T5 - T2| > T diff Adjust the opening degree of the electronic three-way valve (9) to increase the flow rate of the coolant flowing from the outlet of the liquid hydrogen vaporizer (7) to the steam-water separator (10); S4.2.

2. When |T5 - T2| ≤ T diff perform adjustment in step S4.3 according to the humidity of the hydrogen intake of the stack; S4.

3. The humidity value RH3 of the humidity sensor (3) on the pipeline from the outlet of the ejector 4 to the anode of the stack, and the target humidity value RH of the hydrogen intake of the stack t , and the opening degrees of the electronic three-way valve (9) and the electronic three-way valve (11) are controlled according to the following relationship; S4.3.

1. When RH3 < RH t At this time, first adjust the opening of the electronic three-way valve (9) to reduce the flow rate of the coolant flowing out of the liquid hydrogen vaporizer (7) to the steam-water separator (10). On the premise of satisfying |T5 - T2| ≤ T diff , if it is possible to achieve RH3 = RH t , then maintain the opening of the electronic three-way valves (9) and (11), and the system operates normally; if it is not possible to achieve RH3 = RH t , then adjust the opening of the electronic three-way valve (11) to reduce the flow rate of the coolant flowing out of the fuel cell stack to the liquid hydrogen vaporizer (7) until it is possible to achieve RH3 = RH t ; S4.3.

2. When RH3 > RH t First, adjust the opening of the electronic three-way valve (9) to increase the flow rate of the coolant flowing from the outlet of the liquid hydrogen vaporizer (7) to the steam-water separator (10). On the premise of satisfying |T5 - T2| ≤ T diff If RH3 = RH can be achieved t , then maintain the opening of the electronic three-way valves (9) and (11), and the system operates normally; if RH3 = RH cannot be achieved t , then adjust the opening of the electronic three-way valve (11) to increase the flow rate of the coolant flowing from the outlet of the fuel cell stack to the liquid hydrogen vaporizer (7) until RH3 = RH can be achieved t ; S4.3.

3. When RH3 = RH t , the opening degrees of the electronic three-way valves (9) and (11) are maintained, and the system operates normally.

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