A fuel cell control system and method thereof

Abstract

The present invention relates to a fuel cell control system and method in the field of fuel cell technology, including a dry pipeline, a wet pipeline, a heater, a mass flow controller and a battery stack; the dry pipeline and the wet pipeline are connected to form a parallel pipeline, the heater is arranged at the inlet end of the parallel pipeline, and the outlet end of the parallel pipeline is connected to the battery stack; the mass flow controller includes a first mass flow controller and a second mass flow controller, the first mass flow controller is arranged upstream of the dry pipeline, and the second mass flow controller is arranged upstream of the wet pipeline; a humidifier for gas humidification is arranged in the wet pipeline, and the humidifier is connected to the downstream of the second mass flow controller. The present invention divides the gas into dry and wet two paths, controls the flow and temperature of the two paths, and by changing the gas flow of the dry and wet two paths, it can quickly respond to the gas humidity adjustment, solving the problem of long time required to adjust the temperature of the humidification tank and high energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a control system and method for a fuel cell. Background Art

[0002] The fuel cell test platform generally includes an air supply subsystem, a hydrogen supply subsystem, a thermal management subsystem, a control subsystem, an electronic load, and a test system. The temperature, humidity, flow rate, and pressure of the reactant gases, namely air and hydrogen, have a significant impact on the output performance of the fuel cell. Existing fuel cell test platforms usually use external humidification, that is, the reactant gas is humidified to the required humidity outside the fuel cell. Commonly used technologies include bubbling humidification, wet film humidification, steam humidification, ultrasonic humidification, etc. Once it is necessary to test a high-power fuel cell, the test platform uses bubbling humidification with poor effect and high energy consumption; wet film humidification has low efficiency and high noise; steam humidifiers have high investment, high operating costs, and complex design requirements; ultrasonic humidification has high manufacturing costs, etc. At the same time, the above commonly used humidification methods have slow response speeds once the required humidity changes, and can hardly meet the requirements of dynamic response tests.

[0003] Through prior art search, it was found that: Chinese invention patent publication number CN110600770A discloses a fuel cell humidifier test system, including: a dry air generating subsystem, a wet air generating subsystem, a data acquisition subsystem and an automatic control subsystem; the dry air generating subsystem is connected to the dry air inlet of the humidifier to be tested; one end of the wet air generating subsystem is connected to the dry air outlet of the humidifier to be tested, and the other end is connected to the wet air inlet of the humidifier to be tested through a pipeline to form a loop; the wet air outlet of the humidifier to be tested is connected to the external atmosphere; the data acquisition subsystem is distributed on the pipelines of the dry air inlet, dry air outlet, wet air inlet and wet air outlet of the humidifier to be tested, and is respectively used to collect air state data entering / leaving the humidifier to be tested; the automatic control subsystem is respectively connected to the dry air generating subsystem, the wet air generating subsystem and the data acquisition subsystem, and is used to receive air state data, and control the dry air generating subsystem and the wet air generating subsystem. Summary of the invention

[0004] In view of the defects in the prior art, an object of the present invention is to provide a fuel cell control system and method thereof.

[0005] A fuel cell control system provided according to the present invention includes a dry line pipeline, a wet line pipeline, a heater, a mass flow controller and a battery stack;

[0006] The dry pipeline and the wet pipeline are connected to form a parallel pipeline, the heater is arranged at the inlet end of the parallel pipeline, and the outlet end of the parallel pipeline is connected to the battery stack;

[0007] The mass flow controller comprises a first mass flow controller and a second mass flow controller, the first mass flow controller is arranged upstream of the dry pipeline, and the second mass flow controller is arranged upstream of the wet pipeline;

[0008] A humidifier for humidifying gas is arranged in the wet circuit pipeline, and the humidifier is connected to the downstream of the second mass flow controller.

[0009] In some embodiments, the temperature of the gas after being heated by the heater is 5-8° C. higher than a preset temperature, where the preset temperature refers to the temperature of the gas entering the battery stack.

[0010] In some implementations, a temperature sensor S1 is disposed upstream of the heater, and a temperature sensor S2 is disposed downstream of the first mass flow controller. The temperature sensor S1 and the temperature sensor S2 are used to implement power control of the heater.

[0011] In some implementations, a temperature sensor S3 and a pressure sensor P1 are provided in the wet circuit pipeline downstream of the humidifier, and the temperature sensor S3 and the pressure sensor P1 are used to control the temperature and pressure of the humidifier.

[0012] In some embodiments, a temperature sensor S4, a pressure sensor P2, and a humidity sensor H1 are provided in the upstream pipeline of the battery stack.

[0013] In some embodiments, a back-pressure valve is further included, and the back-pressure valve is disposed in a downstream pipeline of the battery stack.

[0014] In some embodiments, a heat exchanger is further included, and the heat exchanger is disposed between the outlet end of the parallel pipeline and the battery stack.

[0015] In some embodiments, a liquid water separation device is further included, and the liquid water separation device is disposed between the heat exchanger and the battery stack.

[0016] The present invention also provides a fuel cell control method, which uses the fuel cell control system and includes the following steps:

[0017] Temperature adjustment step: The heater heats the gas to a temperature 5-8°C higher than the preset temperature value, and the mass flow controller controls the gas flow entering the dry pipeline and the wet pipeline. After the dry and wet mixed gas enters the heat exchanger for heat exchange, the temperature sensor S4 set in the upstream pipeline of the battery stack displays whether the preset temperature has been reached;

[0018] Humidity adjustment step: the heated gas entering the wet circuit pipeline through the second mass flow controller enters the humidifier, and the gas passing through the humidifier is humidified by the humidification adjustment algorithm, and the humidity sensor H1 arranged in the upstream pipeline of the battery stack displays whether the preset humidity is reached;

[0019] Pressure regulation step: The pressure sensor P2 arranged in the upstream pipeline of the battery stack displays whether the preset pressure has been reached, and the gas pressure in the battery stack is regulated by the back pressure valve.

[0020] In some embodiments, in the temperature adjustment step, the humidification adjustment algorithm is:

[0021] Q v,set,g =Q v,dry,g +Q v,wet,g ,

[0022] Among them, Q v refers to volume flow, set refers to set flow, dry and wet refer to dry and wet roads, and g refers to gas;

[0023] Q v,act =Q v,set,g +Q v,vapor,

[0024] Where act refers to the actual flow rate, vapor refers to water vapor (from humidified water);

[0025] According to Dalton's law of partial pressures:

[0026] Q v,wet,g / Q v,vapor =(P (P3) -P* (S5) ) / P* (S5) ,

[0027] P refers to the current total gas pressure, P* refers to the saturated vapor pressure at the corresponding temperature, P3 refers to the reading of pressure sensor P3, and S5 refers to the reading of temperature sensor S5;

[0028] According to the conservation of water mass in gas:

[0029] Q v,vapor ×ρ (S8) =Q v,act ×RH×P* (S4) ×[ρ (S4) ×RH] / P (P2) ,

[0030] ρ refers to the saturated water vapor density at the corresponding temperature and can be obtained by the following formula: ρ = 597 / [(1+0.597 / 230)[(373.15-212) / (T-212)]^5.19)-0.597 / 230](g / m-3 );

[0031] According to the above equation, Q can be calculated v,dry,g With Q v,wet,g , that is, the gas volume flow rate distributed to the dry and wet paths, and controlled by the first mass flow controller and the second mass flow controller.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention divides the gas into two paths, dry and wet, and controls the flow and temperature of the two paths. Moreover, by changing the gas flow of the dry and wet paths, the gas humidity adjustment can be quickly responded to, thus solving the problem of long time and high energy consumption in adjusting the temperature of the humidification tank.

[0034] 2. In the fuel cell control system of the present invention, the heater is arranged before the humidifier, which solves the problem that when the gas temperature of the dry pipeline is lower than the temperature of the wet pipeline after humidification, the two will condense into liquid water after merging, which not only causes water accumulation in the pipeline, but also the gas humidity cannot reach the preset value.

[0035] 3. The present invention further improves the control accuracy of the temperature, humidity and pressure of the gas entering the battery stack by optimizing the composition of the system and adding a heat exchanger, a liquid water separation device, etc.

[0036] 4. The present invention can obtain a fast and high-precision humidity response without using a humidity sensor by means of calculation and calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0038] Figure 1 It is a schematic diagram of the structure of the fuel cell control system of the present invention;

[0039] Among them, the corresponding marks in the accompanying drawings are:

[0040] 1-dry pipeline, 2-wet pipeline, 21-humidifier, 3-heater, 4-mass flow controller, 41-first mass flow controller, 42-second mass flow controller, 5-heat exchanger, 6-liquid water separation device, 7-battery stack, 8-back pressure valve, 9-check valve, 10-supplementary water circuit switch valve. DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0042] Example 1

[0043] The present invention provides a fuel cell control system, including a dry pipeline 1, a wet pipeline 2, a heater 3, a mass flow controller 4 and a battery stack 7. The dry pipeline 1 and the wet pipeline 2 are connected in parallel to form a parallel pipeline, and the dry and wet gases are mixed to reach preset temperature values, humidity values ​​and pressure values ​​and then sent to the battery stack 7. The heater 3 is used to heat the gas, and the mass flow controller 4 is used to control the gas flow in the dry and wet pipelines so that the humidity of the mixed gas reaches a preset value. The present invention divides the gas into dry and wet paths, controls the flow and temperature of the two paths, and changes the gas flow of the dry and wet paths. It can quickly respond to the gas humidity adjustment, thereby solving the problem of long time and high energy consumption required to adjust the temperature of the humidification tank. Specifically:

[0044] The dry pipeline 1 and the wet pipeline 2 are connected in parallel to form a parallel pipeline. The heater 3 is arranged upstream of the parallel pipeline. Two mass flow controllers 4 are arranged upstream of the dry pipeline 1 and the wet pipeline 2, respectively. The mass flow controllers arranged in the dry pipeline 1 and the wet pipeline 2 are marked as the first mass flow controller 41 and the second mass flow controller, respectively. The wet pipeline 2 located downstream of the second mass flow controller 42 is connected with a humidifier 21. The heated gas is humidified by the humidifier 21 and then fully mixed with the dry gas in the dry pipeline 1 in the intersection pipeline of the parallel pipeline, so that the gas meeting the preset temperature, humidity and pressure finally enters the battery stack 7. The humidifier 21 can have various forms, including but not limited to a bubbling humidifier, a membrane humidifier, an ultrasonic humidifier, a steam generator, etc. In some embodiments, a humidification method combining bubbling and spraying can also be used. At the same time, the humidifier 21 is provided with a supplementary water circuit switch valve 10 for controlling the amount of water in the humidifier 21. Preferably, a one-way valve 9 is provided downstream of the first mass flow controller 41 and between the second mass flow controller 42 and the humidifier 21 to prevent the backflow of gas. In the fuel cell control system of the present invention, the heater 3 is provided before the humidifier 21, which solves the problem that when the gas temperature of the dry pipeline is lower than the temperature of the wet pipeline after humidification, the two will condense and precipitate liquid water after confluence, which not only causes water accumulation in the pipeline, but also the gas humidity cannot reach the preset value.

[0045] In order to meet the control accuracy of the fuel cell control system, corresponding sensors are also provided in the fuel cell control system of the present application, and the sensors are mainly temperature sensors, humidity sensors and pressure sensors. Specifically: a temperature sensor S1 is provided upstream of the heater 3, and a temperature sensor S2 is provided in the trunk line 1 downstream of the first mass flow controller 41. A temperature sensor S3 and a pressure sensor P1 are provided in the wet line 2 downstream of the humidifier 21. A temperature sensor S4, a pressure sensor P2 and a humidity sensor H1 are provided in the upstream pipeline of the battery stack 7, and a back pressure valve 8 is provided in the downstream gas exhaust pipeline of the battery stack 7.

[0046] Among them, temperature sensor S1 and temperature sensor S2 are used to adjust the power of heater 3 so that the gas entering the dry pipeline 1 and the wet pipeline 2 reaches the corresponding preset value. The heating method of heater 3 includes thermal oil heating, steam boiler heating, electric heating wire heating, electromagnetic heater heating, etc. Preferably, the temperature of the gas after being heated by heater 3 is 5-8°C higher than the preset temperature, where the preset temperature refers to the temperature of the dry and wet gases after they are mixed and enter the battery stack 7. When the gas flows in the pipeline, some heat will be lost, such as heat dissipation through the pipeline. The above heat loss can be compensated by exceeding the preset temperature by a certain value. If the preset temperature is too high, the water flow required for subsequent plate heat exchanger cooling will be large, the energy consumption will be large, or the difference between the inlet and outlet water temperatures will be large, causing condensation of some gaseous water.

[0047] After the heater 3 heats the gas, the test data after the system stabilizes for 30 minutes are as follows:

[0048]

[0049] The temperature sensor S3 and pressure sensor P1 arranged downstream of the humidifier 21 are used to adjust the corresponding temperature control parameters and pressure control parameters of the humidifier 21. During the adjustment process, the temperature sensor S3 and the pressure sensor P1 are compared and adjusted with the values ​​of the temperature sensor and the pressure sensor built into the humidifier 21. Among them, in order to achieve the required set temperature, it is necessary to control the water in the humidification tank to a certain temperature and keep it constant, so that the saturated humidified gas is stabilized at a certain temperature and pressure. Preferably, the temperature is controlled at 40-90°C, and the pressure is controlled at 2-5bar. Particularly preferably, the temperature is controlled at 90°C and the pressure is controlled at 3bar.

[0050] The temperature sensor S4, pressure sensor P2 and humidity sensor P1 arranged at the gas inlet end of the battery stack 7 are used to detect the temperature, pressure and humidity values ​​of the mixed dry and wet gases, and then adjust the heater 3, mass flow controller 4 and humidifier 21 through the control system to meet the preset requirements.

[0051] Example 2

[0052] This embodiment 2 is formed on the basis of embodiment 1, and further improves the control accuracy of the temperature, humidity and pressure of the gas entering the battery stack by optimizing the composition of the system. Specifically:

[0053] It also includes a heat exchanger 5, which is arranged downstream of the parallel pipelines of the dry pipeline 1 and the wet pipeline 2, and upstream of the battery stack 7. The gas heated by the heater 3 is mixed at the intersection of the parallel pipelines through the dry pipeline 1 and the wet pipeline 2, and then enters the airway cavity of the heat exchanger 5 for heat exchange. Preferably, the heat exchanger 5 uses deionized water to exchange heat with the mixed dry and wet gases, and the heat exchange effect is adjusted by adjusting the inlet and outlet flow of the deionized water. At this time, the temperature sensor S2 and the temperature sensor S3 located upstream of the heat exchanger 5 and the temperature sensor S4 located downstream of the heat exchanger 5 jointly detect the heat exchange power of the heat exchanger 5, and the collected temperature is fed back to the control system to adjust the inlet and outlet flow of the deionized water of the heat exchanger 5 to achieve precise control of the gas temperature and humidity.

[0054] Further preferably, a liquid water separation device 6 is included, and the liquid water separation device 6 is arranged in the upstream pipeline of the battery stack 7. The mixed dry and wet gas passes through the liquid separation device 6 to remove the liquid water in the dry and wet mixed gas before entering the battery stack, further improving the accuracy of the gas humidity value entering the battery stack 7. Preferably, when a heat exchanger 5 is provided in the system, the liquid separation device 6 is arranged between the heat exchanger 5 and the battery stack 7. After the dry and wet mixed gas after heat exchange in the heat exchanger 5 passes through the liquid water separation device 6, the liquid water in the dry and wet mixed gas is separated.

[0055] Example 3

[0056] This embodiment 3 is a fuel cell control method formed on the basis of embodiment 2, using the above-mentioned fuel cell control system, and includes the following steps:

[0057] Temperature adjustment step: the heater 3 heats the gas to a temperature 5-8°C higher than the preset temperature value, the mass flow controller 4 controls the gas flow entering the dry pipeline 1 and the wet pipeline 2, and after the dry and wet mixed gas enters the heat exchanger 5 for heat exchange, the temperature sensor S4 arranged in the upstream pipeline of the battery stack 7 displays whether the preset temperature has been reached;

[0058] Humidity adjustment step: the heated gas entering the wet circuit pipeline 2 through the second mass flow controller 42 enters the humidifier 21, and the gas entering the humidifier 21 is humidified by the humidification adjustment algorithm, and the humidity sensor H1 arranged in the upstream pipeline of the battery stack 7 displays whether the preset humidity is reached;

[0059] Pressure regulation step: The pressure sensor P2 arranged in the upstream pipeline of the battery stack 7 displays whether the preset pressure has been reached, and the gas pressure in the battery stack 7 is adjusted by the back pressure valve 8.

[0060] Wherein, in the temperature adjustment step, the humidification adjustment algorithm is:

[0061] Q v,set,g =Q v,dry,g +Q v,wet,g ,

[0062] Among them, Q v refers to volume flow, set refers to set flow, dry and wet refer to dry and wet roads, and g refers to gas;

[0063] Q v,act =Q v,set,g +Q v,vapor,

[0064] Where act refers to the actual flow rate, vapor refers to water vapor (from humidified water);

[0065] According to Dalton's law of partial pressures:

[0066] Q v,wet,g / Q v,vapor =(P (P3) -P* (S5) ) / P* (S5) ,

[0067] P refers to the current total gas pressure, P* refers to the saturated vapor pressure at the corresponding temperature, P3 refers to the reading of pressure sensor P3, and S5 refers to the reading of temperature sensor S5;

[0068] According to the conservation of water mass in gas:

[0069] Q v,vapor ×ρ (S8) =Q v,act ×RH×P* (S4) ×[ρ (S4) ×RH] / P (P2) ,

[0070] ρ refers to the saturated water vapor density at the corresponding temperature and can be obtained by the following formula: ρ = 597 / [(1+0.597 / 230)[(373.15-212) / (T-212)]^5.19)-0.597 / 230](g / m -3 );

[0071] According to the above equation, Q can be calculated v,dry,g With Q v,wet,g, that is, the gas volume flow rate distributed to the dry and wet paths, and is controlled by the first mass flow controller 41 and the second mass flow controller 42.

[0072] Calibration process: Calibrate the humidity through the humidity sensor, and calibrate the target temperature and target humidity. At the target temperature, when the calculated air flow Q v,dry,g With Q v,wet,g The humidity is a, which is less than the target humidity. v,wet,g , set to (100+x)% to obtain the target humidity; when the actual humidity is a, which is greater than the target humidity, by reducing Q v,wet,g , set to (100-x)% to get the target humidity. By calibrating at different temperatures in this way, the offset of the target humidity is obtained. In practical applications, calibration is performed by looking up the table and calculating by interpolation. The example calibration table is as follows:

[0073]

[0074]

[0075] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0076] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A fuel cell control system, characterized in that: It comprises a dry pipeline (1), a wet pipeline (2), a heater (3), a mass flow controller (4) and a battery stack (7); The dry pipeline (1) and the wet pipeline (2) are connected to form a parallel pipeline, the heater (3) is arranged at the inlet end of the parallel pipeline, and the outlet end of the parallel pipeline is connected to the battery stack (7); The mass flow controller (4) comprises a first mass flow controller (41) and a second mass flow controller (42), wherein the first mass flow controller (41) is arranged upstream of the dry pipeline (1), and the second mass flow controller (42) is arranged upstream of the wet pipeline (2); A humidifier (21) for humidifying gas is arranged in the wet circuit pipeline (2), and the humidifier (21) is connected to the downstream of the second mass flow controller (42); The temperature of the gas after being heated by the heater (3) is 5-8° C. higher than a preset temperature, wherein the preset temperature refers to the temperature of the gas entering the battery stack (7); A temperature sensor S1 is provided upstream of the heater (3), and a temperature sensor S2 is provided downstream of the first mass flow controller (41), wherein the temperature sensor S1 and the temperature sensor S2 are used to realize power control of the heater (3); A temperature sensor S3 and a pressure sensor P1 are provided in the wet circuit pipeline (2) downstream of the humidifier (21), and the temperature sensor S3 and the pressure sensor P1 are used to control the temperature and pressure of the humidifier (21); A temperature sensor S4, a pressure sensor P2 and a humidity sensor H1 are arranged in the upstream pipeline of the battery stack (7); It also comprises a back pressure valve (8), wherein the back pressure valve (8) is arranged in a downstream pipeline of the battery stack (7).

2. The fuel cell control system according to claim 1, characterized in that: It also includes a heat exchanger (5), which is arranged between the outlet end of the parallel pipeline and the battery stack (7).

3. The fuel cell control system according to claim 2, characterized in that: It also comprises a liquid water separation device (6), wherein the liquid water separation device (6) is arranged between the heat exchanger (5) and the battery stack (7).

4. A fuel cell control method, characterized in that: The fuel cell control system according to any one of claims 1 to 3 comprises the following steps: Temperature adjustment step: the heater (3) heats the gas to a temperature 5-8°C higher than a preset temperature value, the mass flow controller (4) controls the gas flow entering the dry pipeline (1) and the wet pipeline (2), and after the dry and wet mixed gas enters the heat exchanger (5) for heat exchange, a temperature sensor S4 arranged in the upstream pipeline of the battery stack (7) indicates whether the preset temperature has been reached; Humidity adjustment step: the heated gas entering the wet circuit pipeline (2) through the second mass flow controller (42) enters the humidifier (21), the gas passing through the humidifier (21) is humidified by a humidification adjustment algorithm, and a humidity sensor H1 arranged in the upstream pipeline of the battery stack (7) displays whether the preset humidity has been reached; Pressure regulation step: a pressure sensor P2 disposed in the upstream pipeline of the battery stack (7) is used to display whether a preset pressure has been reached, and the gas pressure in the battery stack (7) is regulated by a back pressure valve (8).

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