Hydrogen fuel cell cooling system cooling flow monitoring method

Abstract

This invention discloses a method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system, belonging to the field of hydrogen fuel cell technology. The method includes: setting the heating power of an electric heater in the hydrogen fuel cell cooling system; detecting the inlet and outlet temperatures of the electric heater to obtain the temperature difference between them; calculating the coolant flow rate through the electric heater using a heat power formula based on the temperature difference; determining the flow rate of each branch of the cooling system by consulting a table showing the ratio of the coolant flow rate through the flow control valve to the flow rate of each branch based on the coolant flow rate and the current flow control valve opening; adjusting the pump speed and flow control valve opening in the hydrogen fuel cell cooling system based on the determined flow rate; and performing fault diagnosis of the hydrogen fuel cell cooling system based on the coolant flow rate through the electric heater and the theoretical flow rate under current operating conditions. This invention enables real-time monitoring of coolant flow rate and is low-cost.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen fuel cell technology, and particularly relates to a method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system. Background Technology

[0002] In practical applications, the cooling system of a hydrogen fuel cell system cannot monitor the actual flow rate in real time. The cooling system can only control the water pump speed and valve opening during the initial calibration to control the stack water temperature. It cannot obtain the actual flow rate of each branch to determine faults such as water pump performance, pipeline leaks, and water shortage. In addition, the cooling system cannot obtain the actual flow rate under the current operating conditions in practical applications, making it impossible to precisely control the flow control valve and water pump. In terms of fault diagnosis, problems such as water shortage, blockage, and water pump performance degradation in the cooling system cannot be diagnosed in a timely manner, which can easily lead to serious faults such as stack burn-out. Summary of the Invention

[0003] To address some or all of the technical problems existing in the prior art, the present invention provides a method for monitoring the cooling flow of a hydrogen fuel cell cooling system, which can realize real-time and accurate monitoring and control of the cooling flow of the hydrogen fuel cell cooling system, timely diagnosis of cooling system faults, effectively reduce system energy consumption and improve the safety and reliability of operation.

[0004] The technical solution of the present invention is as follows:

[0005] A method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system is provided, comprising:

[0006] Set the heating power for the electric heater in the hydrogen fuel cell cooling system;

[0007] The temperature difference between the inlet and outlet temperatures of the electric heater is obtained by detecting the inlet and outlet temperatures of the electric heater.

[0008] Based on the obtained temperature difference, the flow rate of the coolant flowing through the electric heater is calculated using the heat power formula;

[0009] Based on the coolant flow rate through the electric heater and the current flow control valve opening, the pre-calibrated table of flow control valve opening versus flow rate ratio of each branch of the cooling system is consulted to determine the flow rate of each branch of the cooling system. Based on the determined flow rates of each branch of the cooling system, the pump speed and flow control valve opening in the hydrogen fuel cell cooling system are adjusted accordingly. Furthermore, based on the coolant flow rate through the electric heater and the theoretical flow rate under the current operating conditions, fault diagnosis of the hydrogen fuel cell cooling system is performed.

[0010] Furthermore, in the above-mentioned method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system, the thermal power formula is:

[0011] ;

[0012] in, Indicates heating power. Indicates fluid density, Indicates flow rate. Indicates specific heat capacity. This indicates the temperature difference between the inlet and outlet temperatures of the electric heater.

[0013] Furthermore, in the above-mentioned method for monitoring the cooling flow of a hydrogen fuel cell cooling system, the heating power is 1kW.

[0014] Furthermore, in the above-mentioned method for monitoring the cooling flow of the hydrogen fuel cell cooling system, the inlet and outlet temperatures of the electric heater are detected using temperature sensors.

[0015] Furthermore, in the above-mentioned method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system, the step of adjusting the pump speed and flow control valve opening in the hydrogen fuel cell cooling system based on the determined flow rate of each branch of the cooling system includes:

[0016] Based on the deviation between the determined flow rate of each branch of the cooling system and the target flow rate of each branch of the cooling system, as well as the deviation between the actual measured value of the fuel cell inlet temperature and the target temperature in the cooling system, adjust the water pump speed, the flow control valve opening, and the radiator speed.

[0017] After each adjustment, the flow rate of each branch of the cooling system is redefined. Based on the deviation between the determined flow rate of each branch of the cooling system and the target flow rate, as well as the deviation between the actual measured value of the fuel cell inlet temperature and the target temperature, the pump speed, flow control valve opening, and radiator speed are adjusted until the deviation between the flow rate of each branch of the cooling system and the target flow rate, as well as the deviation between the actual measured value of the fuel cell inlet temperature and the target temperature, meet the set requirements.

[0018] Furthermore, in the above-mentioned method for monitoring the cooling flow of the hydrogen fuel cell cooling system, the stack inlet temperature is measured using a temperature sensor.

[0019] Furthermore, in the above-mentioned method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system, the step of performing fault diagnosis of the hydrogen fuel cell cooling system based on the flow rate of the coolant flowing through the electric heater and the theoretical flow rate under the current operating conditions includes:

[0020] If the flow rate of coolant flowing through the electric heater is greater than the theoretical flow rate, and the deviation between the two exceeds the first preset threshold, then the cooling system is determined to have the following fault: other branches of the cooling system are blocked.

[0021] If the flow rate of coolant flowing through the electric heater is less than the theoretical flow rate, and the deviation between the two exceeds the second preset threshold, then the cooling system is determined to have at least one of the following faults: insufficient coolant in the cooling system, incomplete degassing of the cooling system, leakage of coolant in the cooling system, or reduced performance of the water pump.

[0022] Furthermore, in the above-mentioned method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system, the method further includes:

[0023] When a malfunction is detected in the cooling system, an alarm or protection mechanism is triggered.

[0024] The main advantages of the technical solution of this invention are as follows:

[0025] The cooling flow monitoring method for hydrogen fuel cell cooling systems of the present invention indirectly calculates and monitors the coolant flow rate in real time based on the thermal power formula, realizing precise system control and fault diagnosis without increasing hardware costs, and significantly improving the reliability, safety and economy of hydrogen fuel cell systems. Attached Figure Description

[0026] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and constitute a part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0027] Figure 1 A schematic flowchart of a method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system provided in an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the structure of the hydrogen fuel cell cooling system to which the cooling flow monitoring method for the hydrogen fuel cell cooling system provided in this embodiment of the invention is applicable.

[0029] Figure 3 A schematic diagram illustrating the feedback adjustment of the water pump speed and flow control valve opening in the hydrogen fuel cell cooling system in the cooling flow monitoring method provided in this embodiment of the invention.

[0030] Figure 4 This is a schematic diagram illustrating the principle of fault diagnosis in a hydrogen fuel cell cooling system using a cooling flow monitoring method provided in an embodiment of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0032] The following is in conjunction with the appendix Figure 1-4 The technical solutions provided in the embodiments of the present invention will be described in detail.

[0033] As attached Figure 1 As shown, this embodiment of the invention provides a method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system, the method comprising the following steps S1-S4:

[0034] Step S1: Set the heating power of the electric heater in the hydrogen fuel cell cooling system;

[0035] Optionally, the heating power is set to 1kW.

[0036] For example, when monitoring the cooling flow of a hydrogen fuel cell cooling system, the fuel cell controller (FCU) provides the electric heater with a heating power of 1 kW.

[0037] Step S2: Detect the inlet and outlet temperatures of the electric heater to obtain the temperature difference between the inlet and outlet temperatures of the electric heater;

[0038] refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of a hydrogen fuel cell cooling system to which the cooling flow monitoring method for a hydrogen fuel cell cooling system provided in this embodiment of the invention applies. The cooling system includes a water pump, an intercooler, an electric heater, an expansion tank, a fuel cell stack, a flow control valve, and a radiator, and their connections are as follows: Figure 2 As shown.

[0039] In this embodiment of the invention, temperature sensors are installed at the inlet and outlet of the electric heater. The inlet and outlet temperatures are collected in real time by the installed temperature sensors, thereby calculating the temperature difference between the inlet and outlet temperatures of the electric heater.

[0040] Step S3: Calculate the flow rate of the coolant flowing through the electric heater using the heat power formula based on the obtained temperature difference;

[0041] Specifically, the formula for heat power is expressed as: ;

[0042] in, Indicates heating power. Indicates fluid density, Indicates flow rate. Indicates specific heat capacity. This indicates the temperature difference between the inlet and outlet temperatures of the electric heater. =Outlet temperature - Inlet temperature.

[0043] Assuming all the heat energy of the electric heater is absorbed by the coolant and neglecting heat loss, based on the law of conservation of energy, the heat power formula is used. , deformed This allows us to calculate the flow rate of the coolant passing through the electric heater.

[0044] Step S4: Based on the coolant flow rate through the electric heater and the current flow control valve opening, consult the pre-calibrated cooling system flow control valve opening-flow ratio table for each branch of the cooling system to determine the flow rate of each branch of the cooling system. Based on the determined flow rates of each branch of the cooling system, adjust the water pump speed and flow control valve opening in the hydrogen fuel cell cooling system accordingly. Also, based on the coolant flow rate through the electric heater and the theoretical flow rate under the current operating conditions, perform fault diagnosis of the hydrogen fuel cell cooling system.

[0045] Specifically, during the operation of the cooling system, the flow ratio table of the cooling system flow control valve opening and the flow ratio of each branch of the cooling system is consulted to determine the flow ratio of each branch of the cooling system under the current flow control valve opening. Based on the coolant flow rate through the electric heater and the flow ratio of each branch of the cooling system, the flow rate of each branch of the cooling system can be calculated. This allows for further adjustment of the flow control valve opening and water pump speed based on the acquired flow data, thus rationally controlling the flow rate of each branch of the cooling system to reduce energy consumption. Simultaneously, based on the coolant flow rate through the electric heater and the theoretical flow rate under current operating conditions, fault diagnosis of the hydrogen fuel cell cooling system can be performed to determine whether there are faults such as insufficient coolant, leakage, or degraded water pump performance, thereby achieving self-diagnosis of cooling system faults.

[0046] Specifically, in this embodiment of the invention, the relationship table between the opening degree of the cooling system flow control valve and the flow ratio of each branch of the cooling system is pre-calibrated using the following method:

[0047] On the test bench, a temporary high-precision flow sensor was installed on the cooling system. The flow control valve was controlled to be at different opening degrees, and the flow rate of coolant flowing through the electric heater and the flow rate of coolant in other branches of the system (such as the stack branch, radiator branch, etc.) were recorded at each valve opening degree. Since the total amount of coolant is conserved, the total flow rate of the system is equal to the sum of the flow rates of each branch. Through multiple measurements, the ratio of the "flow rate of the electric heater branch" to the "total flow rate of the cooling system" at each valve opening degree was determined, as well as the flow ratio of each branch of the cooling system. Thus, a table of the flow control valve opening degree of the cooling system and the flow ratio of each branch of the cooling system was constructed and written into the program of the fuel cell controller.

[0048] Furthermore, in this embodiment of the invention, the theoretical flow rate under different operating conditions can be obtained in advance by installing a temporary high-precision flow sensor on the cooling system, conducting corresponding test experiments for different operating conditions, and writing the result into the program of the fuel cell controller.

[0049] In this embodiment of the invention, a set of flow control valve opening and water pump speed parameters correspond to a working condition, and the current working condition is determined based on the current flow control valve opening and water pump speed.

[0050] refer to Figure 3 , Figure 3 This is a schematic diagram illustrating the feedback adjustment of the water pump speed and flow control valve opening in the hydrogen fuel cell cooling system within the cooling flow monitoring method provided in this embodiment of the invention.

[0051] Specifically, in this embodiment of the invention, the feedback adjustment of the water pump speed and flow control valve opening in the hydrogen fuel cell cooling system based on the determined flow rates of each branch of the cooling system further includes:

[0052] Based on the deviation between the determined flow rate of each branch of the cooling system and the target flow rate of each branch of the cooling system, as well as the deviation between the actual measured value of the fuel cell inlet temperature and the target temperature in the cooling system, adjust the water pump speed, the flow control valve opening, and the radiator speed.

[0053] After each adjustment, the flow rate of each branch of the cooling system is redefined. Based on the deviation between the determined flow rate of each branch of the cooling system and the target flow rate, as well as the deviation between the actual measured value of the fuel cell inlet temperature and the target temperature, the pump speed, flow control valve opening, and radiator speed are adjusted until the deviation between the flow rate of each branch of the cooling system and the target flow rate, as well as the deviation between the actual measured value of the fuel cell inlet temperature and the target temperature, meet the set requirements.

[0054] The target flow rate and target temperature are set according to actual needs, and the setting requirements are set according to actual needs.

[0055] The inlet temperature of the fuel cell stack can be obtained by installing a temperature sensor at the inlet location.

[0056] In this embodiment of the invention, when the flow rate of each branch of the cooling system is less than the target flow rate, the pump speed can be increased and / or the flow control valve opening can be increased; when the flow rate of each branch of the cooling system is greater than the target flow rate, the pump speed can be decreased and / or the flow control valve opening can be reduced; when the actual measured value of the fuel cell inlet temperature is less than the target temperature, the pump speed can be decreased and / or the flow control valve opening can be reduced and / or the radiator speed can be reduced; when the actual measured value of the fuel cell inlet temperature is greater than the target temperature, the pump speed can be increased and / or the flow control valve opening can be increased and / or the radiator speed can be increased.

[0057] In this embodiment of the invention, by comparing parameters such as the flow rate of each branch of the cooling system and the inlet temperature of the fuel cell stack with the set target values, and dynamically adjusting the pump speed, flow control valve opening and radiator speed according to the comparison results, precise thermal management with optimal energy consumption can be achieved.

[0058] refer to Figure 4 , Figure 4 This is a schematic diagram illustrating the principle of fault diagnosis in a hydrogen fuel cell cooling system using a cooling flow monitoring method provided in an embodiment of the present invention.

[0059] Specifically, in this embodiment of the invention, fault diagnosis of the hydrogen fuel cell cooling system is performed based on the flow rate of the coolant flowing through the electric heater and the theoretical flow rate under the current operating conditions, further including:

[0060] If the flow rate of coolant flowing through the electric heater is greater than the theoretical flow rate, and the deviation between the two exceeds the first preset threshold, then the cooling system is determined to have the following fault: other branches of the cooling system are blocked.

[0061] If the flow rate of coolant flowing through the electric heater is less than the theoretical flow rate, and the deviation between the two exceeds the second preset threshold, then the cooling system is determined to have at least one of the following faults: insufficient coolant in the cooling system, incomplete degassing of the cooling system, leakage of coolant in the cooling system, or reduced performance of the water pump.

[0062] In this embodiment of the invention, the current operating condition is determined based on the current opening degree of the flow control valve and the pump speed, and the theoretical flow rate under the current operating condition is obtained from the theoretical flow rate data under different pre-calibrated and stored operating conditions.

[0063] In this embodiment of the invention, the first preset threshold and the second preset threshold are predetermined based on the flow fluctuation range during normal operation of the cooling system.

[0064] Furthermore, in this embodiment of the invention, the cooling flow monitoring method for the hydrogen fuel cell cooling system may further include: triggering an alarm or protection mechanism when a fault is determined to exist in the cooling system.

[0065] In this embodiment of the invention, by triggering an alarm or protection mechanism when a fault is detected in the cooling system, the fault can be prevented from escalating and causing the fuel cell stack to burn out.

[0066] The principle of the cooling flow monitoring method for a hydrogen fuel cell cooling system provided in this invention includes:

[0067] Energy conservation and flow calculation principle: The electrical energy of the electric heater is converted into the heat energy of the coolant. Under ideal conditions, the heating power equals the heat absorption power of the coolant, that is... The temperature difference between the inlet and outlet temperatures of the electric heater was measured. Combined with known , , It can indirectly and accurately calculate the flow rate of coolant passing through the electric heater. It enables low-cost, indirect flow monitoring without the need for additional flow sensors.

[0068] The principle of the flow ratio correspondence: When the cooling system is running normally and stably, there is a stable experimental calibration relationship between the opening of the flow control valve and the flow ratio of each branch of the cooling system. Therefore, as long as the flow rate of a certain branch (such as the electric heater branch) is known, the flow rate of all branches can be calculated through the calibrated ratio relationship, realizing indirect monitoring of the flow rate of multiple branches.

[0069] Closed-loop control principle: Using "fuel cell inlet temperature and flow rate of each branch" as feedback signals, and "water pump speed, flow control valve opening, and radiator speed" as control variables, closed-loop control is performed. The control variables are adjusted in real time according to the feedback signals, which can keep the cooling system in the optimal working state at all times, ensure stable fuel cell temperature and optimize energy consumption.

[0070] Fault diagnosis principle: When the cooling system is running normally and stably, the flow rate of each branch of the cooling system has a corresponding theoretical flow rate range for different operating conditions. By comparing the deviation between the actual flow rate and the theoretical flow rate, and combining the logical relationships such as "blockage leading to flow transfer, leakage or lack of liquid leading to flow rate decrease", the fault classification and diagnosis can be achieved.

[0071] In summary, compared with the prior art, the cooling flow monitoring method for hydrogen fuel cell cooling systems of the present invention has the following advantages and beneficial effects:

[0072] There is no need to install flow sensors for each branch. By using the method of "heating + temperature difference calculation + proportional lookup table", it is possible to achieve real-time and accurate monitoring of flow in multiple branches at low cost. Based on the monitoring results, the water pump, flow control valve and radiator are dynamically adjusted to optimize the distribution of cooling flow, improve the accuracy of fuel cell stack temperature control, reduce water pump energy consumption and avoid excessive delivery of coolant.

[0073] It can promptly identify faults such as "liquid shortage, blockage, leakage, and degraded pump performance," providing early warnings and effectively preventing serious accidents such as fuel cell stack burnout due to cooling failure, thus significantly improving the safety and reliability of system operation.

[0074] By combining pre-calibrated and stored relational tables and theoretical flow data with closed-loop control, the cooling system can adapt to different operating conditions, quickly adjust the flow distribution, and always ensure that the fuel cell stack operates within the optimal temperature range, while minimizing the energy consumption of the cooling system and improving the energy efficiency ratio of the hydrogen fuel cell system.

[0075] It can reduce the use of flow sensors, reduce hardware costs and system wiring complexity; the control logic is based on existing temperature sensors and algorithms, making it easy to deploy and maintain in an engineering manner.

[0076] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Additionally, the terms "front," "back," "left," "right," "upper," and "lower" in this document refer to the placement shown in the accompanying drawings.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system, characterized in that, include: Set the heating power for the electric heater in the hydrogen fuel cell cooling system; The temperature difference between the inlet and outlet temperatures of the electric heater is obtained by detecting the inlet and outlet temperatures of the electric heater. Based on the obtained temperature difference, the flow rate of the coolant flowing through the electric heater is calculated using the heat power formula; Based on the coolant flow rate through the electric heater and the current flow control valve opening, the pre-calibrated cooling system flow control valve opening-flow ratio table of each branch of the cooling system is consulted to determine the flow rate of each branch of the cooling system. Based on the determined flow rate of each branch of the cooling system, the water pump speed and flow control valve opening in the hydrogen fuel cell cooling system are adjusted accordingly. Furthermore, based on the coolant flow rate through the electric heater and the theoretical flow rate under the current operating conditions, fault diagnosis of the hydrogen fuel cell cooling system is performed. The formula for heat power is: ； in, Indicates heating power. Indicates fluid density, Indicates flow rate. Indicates specific heat capacity. This indicates the temperature difference between the inlet and outlet temperatures of the electric heater. The feedback adjustment of the water pump speed and flow control valve opening in the hydrogen fuel cell cooling system based on the determined flow rates of each branch of the cooling system includes: Based on the deviation between the determined flow rate of each branch of the cooling system and the target flow rate of each branch of the cooling system, as well as the deviation between the actual measured value of the fuel cell inlet temperature and the target temperature in the cooling system, adjust the water pump speed, the flow control valve opening, and the radiator speed. After each adjustment, the flow rate of each branch of the cooling system is redefined. Based on the deviation between the determined flow rate of each branch of the cooling system and the target flow rate, as well as the deviation between the actual measured value of the fuel cell inlet temperature and the target temperature, the pump speed, flow control valve opening, and radiator speed are adjusted until the deviation between the flow rate of each branch of the cooling system and the target flow rate, as well as the deviation between the actual measured value of the fuel cell inlet temperature and the target temperature, meet the set requirements.

2. The method for monitoring cooling flow rate of a hydrogen fuel cell cooling system according to claim 1, characterized in that, The heating power is 1kW.

3. The method for monitoring cooling flow rate of a hydrogen fuel cell cooling system according to claim 1, characterized in that, The inlet and outlet temperatures of the electric heater are detected using temperature sensors.

4. The method for monitoring cooling flow rate of a hydrogen fuel cell cooling system according to claim 1, characterized in that, The inlet temperature of the fuel cell stack is measured using a temperature sensor.

5. The method for monitoring cooling flow rate of a hydrogen fuel cell cooling system according to claim 1, characterized in that, The process of diagnosing hydrogen fuel cell cooling system faults based on the coolant flow rate through the electric heater and the theoretical flow rate under current operating conditions includes: If the flow rate of coolant flowing through the electric heater is greater than the theoretical flow rate, and the deviation between the two exceeds the first preset threshold, then the cooling system is determined to have the following fault: other branches of the cooling system are blocked. If the flow rate of coolant flowing through the electric heater is less than the theoretical flow rate, and the deviation between the two exceeds the second preset threshold, then the cooling system is determined to have at least one of the following faults: insufficient coolant in the cooling system, incomplete degassing of the cooling system, leakage of coolant in the cooling system, or reduced performance of the water pump.

6. The method for monitoring the cooling flow rate of a hydrogen fuel cell cooling system according to claim 1 or 5, characterized in that, The method further includes: When a malfunction is detected in the cooling system, an alarm or protection mechanism is triggered.

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