Method and device for estimating temperature of electric pile, fuel cell system, equipment and medium

Abstract

The invention relates to the field of fuel cells, and provides an electric pile temperature estimation method and device, a fuel cell system, equipment and a medium. The galvanic pile temperature estimation method comprises the following steps: dividing the time when a cooling liquid flows through a galvanic pile into a plurality of unit times, and obtaining the number n of the unit times required by the cooling liquid to flow through the galvanic pile and the temperature T outlet when the cooling liquid flows out of the galvanic pile; setting the temperature T electric pile in the electric pile to be equal to T outlet + a, and starting from n = 1, sequentially substituting into a formula until Tn is calculated; comparing the calculated Tn with the T outlet, gradually increasing the preset threshold value a when the Tn is smaller than the T outlet, and calculating the Tn through the formula again from n = 1 after the preset threshold value a is increased every time until the preset threshold value a is increased until the calculated Tn is just not smaller than the T outlet; and when the calculated Tn is just not less than the Toutlet, determining the Toutlet + a'as the temperature Tstack in the stack. According to the invention, the internal temperature of the electric pile can be estimated based on the cooling liquid outlet temperature of the electric pile, and the electric pile can be better protected.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a method, apparatus, fuel cell system, equipment, and medium for predicting fuel cell stack temperature. Background Technology

[0002] A proton exchange membrane fuel cell (PEMFC) is a power generation device that generates electricity by electrochemically reacting hydrogen on the anode side of the fuel cell stack with oxygen in the air on the cathode side. It is a pollution-free clean energy source.

[0003] In fuel cell systems, to prevent damage to the stack due to excessive internal temperature during operation, a temperature limit is typically set. Once this limit is reached, the system will reduce the load on the stack or shut it down directly to protect it. The core of this over-temperature protection strategy is the determination of the internal temperature of the stack.

[0004] Currently, the internal temperature of the fuel cell stack is not monitored in the entire system; instead, the internal temperature is determined by monitoring the inlet and outlet temperatures of the coolant. However, from a heat transfer perspective, once the fuel cell system is operating normally, the temperature of the stack itself is definitely greater than or equal to the coolant outlet temperature.

[0005] Therefore, the existing method of judging whether the internal temperature of the fuel cell stack is too high based on the inlet and outlet temperatures of the coolant is not accurate enough. It is easy for the fuel cell stack to be damaged due to the actual internal temperature exceeding the limit, which is not conducive to the protection of the fuel cell stack. Summary of the Invention

[0006] In view of this, the present invention aims to propose a method for predicting the temperature of a fuel cell stack, so as to achieve the estimation of the internal temperature of the fuel cell stack and thus better protect the fuel cell stack.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A method for predicting fuel cell stack temperature, the method comprising:

[0009] The time it takes for the coolant to flow through the fuel cell stack is divided into multiple unit times, and the number of unit times n required for the coolant to flow through the fuel cell stack and the temperature T of the coolant when it flows out of the fuel cell stack are obtained. 出口 ;

[0010] Set the internal temperature T of the fuel cell stack. 电堆 =T 出口 +a, and starting from n=1, substitute into the formula sequentially: H*(T) 电堆 -Tn-1 )=c*m*(T n -T n-1 ), until T is calculated. n Where a is a preset threshold greater than 0, H is the heat transfer coefficient and represents the heat transferred per unit temperature difference per unit time, c is the specific heat capacity of the coolant, m is the mass of the coolant in the first unit time, and when n=1, T0 represents the temperature of the coolant when it enters the fuel cell stack in the first unit time.

[0011] Compare the calculated T n With T 出口 and in T n Less than T 出口 At that time, the preset threshold 'a' is increased successively, and after each increase of the preset threshold 'a', the process restarts from n=1, using the formula: H*(T 电堆 -T n-1 )=c*m*(T n -T n-1 Calculate T n Until the preset threshold a increases to the level that makes the calculated T n Just not less than T 出口 ;

[0012] In the calculated T n Just not less than T 出口 At that time, T 出口 +a' is determined to be the internal temperature T of the fuel cell stack. 电堆 And a' is the preset threshold a increased to T n Just not less than T 出口 The value at that time.

[0013] Furthermore, obtaining the quantity n of unit time required for the coolant to flow through the fuel cell stack includes:

[0014] Obtain the coolant flow rate m per unit time, and get the corresponding coolant volume v from m / ρ, where ρ is the density of the coolant;

[0015] The volume v of coolant corresponding to multiple unit times is accumulated until the accumulated volume v of coolant is exactly not less than the volume V of the cooling channel inside the fuel cell stack.

[0016] The number of times the accumulated result is exactly not less than the volume V of the cooling channel inside the fuel cell is accumulated is determined as the number of unit times n required for the cooling fluid to flow through the fuel cell.

[0017] Furthermore, through the formula Obtain the coolant flow rate m per unit time, where Δp is the pressure difference between the coolant inlet and outlet of the fuel cell stack. maxThe maximum pressure difference between the inlet and outlet of the fuel cell stack coolant, m max This represents the maximum flow rate of the fuel cell stack coolant.

[0018] Furthermore, the heat transfer coefficient H is determined in the following manner:

[0019] Construct an experimental fuel cell stack and put it into operation;

[0020] The coolant flow time through the experimental fuel cell stack is controlled to be z unit time, and the temperature T of the coolant outlet of the experimental fuel cell stack is recorded after z unit time. z And the temperature T of the experimental fuel cell stack body. 电堆本体 ;

[0021] Maintain the temperature of the coolant entering the experimental fuel cell stack, and the temperature T of the experimental fuel cell stack body. 电堆本体 The flow rate of the coolant flowing through the experimental fuel cell stack is increased while keeping the flow rate constant. The time for the coolant to flow through the experimental fuel cell stack is controlled to be z-1 unit time, and the temperature T at the outlet of the coolant of the experimental fuel cell stack is recorded after z-1 unit time. z-1 ;

[0022] Through the formula: The heat transfer coefficient H is calculated, where c is the specific heat capacity of the coolant, and m... 单位时间 This refers to the mass of coolant per unit time.

[0023] Furthermore, the experimental fuel cell stack operates in a medium-to-high power mode.

[0024] Furthermore, the preset threshold a is a natural number greater than 0.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The fuel cell stack temperature prediction method of the present invention divides the time for coolant to flow through the fuel cell stack into multiple unit times, obtains the number of unit times n required for coolant to flow through the fuel cell stack, and the temperature T of coolant when it flows out of the fuel cell stack. 出口 Then set the internal temperature T of the fuel cell stack. 电堆 =T 出口 +a, and starting from n=1, substitute into the formula sequentially until T is obtained. n Then compare the calculated T n With T 出口 and in T n Less than T 出口 At that time, the preset threshold 'a' is increased successively, and after each increase of the preset threshold 'a', the process restarts from n=1, and T is calculated using the formula. n Until the preset threshold a increases to the level that makes the calculated Tn Just not less than T 出口 Finally, in the calculated T n Just not less than T 出口 At that time, T 出口 +a' is determined to be the internal temperature T of the fuel cell stack. 电堆 This allows for the estimation of the internal temperature of the fuel cell stack based on the outlet temperature of the coolant. Compared to the method of judging by the inlet and outlet temperatures of the coolant, this method can obtain a more reasonable internal temperature of the fuel cell stack, which is beneficial for better protection of the fuel cell stack.

[0027] Another object of the present invention is to provide a fuel cell stack temperature prediction device, which includes an acquisition module, a first processing module, a second processing module and a determination module;

[0028] The acquisition module is used to divide the time for the coolant to flow through the fuel cell stack into multiple unit times, and to acquire the number n of unit times n required for the coolant to flow through the fuel cell stack, and the temperature T of the coolant when it flows out of the fuel cell stack. 出口 ;

[0029] The first processing module is used to set the internal temperature T of the fuel cell stack. 电堆 =T 出口 +a, and starting from n=1, substitute into the formula sequentially: H*(T) 电堆 -T n-1 )=c*m*(T n -T n-1 ), until T is calculated. n Where a is a preset threshold greater than 0, H is the heat transfer coefficient and represents the heat transferred per unit temperature difference per unit time, c is the specific heat capacity of the coolant, m is the mass of the coolant in the first unit time, and when n=1, T0 represents the temperature of the coolant when it enters the fuel cell stack in the first unit time.

[0030] The second processing module is used to compare the calculated T n With T 出口 and in T n Less than T 出口 At that time, the preset threshold 'a' is increased successively, and after each increase of the preset threshold 'a', the process restarts from n=1, using the formula: H*(T 电堆 -T n-1 )=c*m*(T n -T n-1 Calculate T n Until the preset threshold a increases to the level that makes the calculated T n Just not less than T 出口 ;

[0031] The determining module is used to calculate T.n Just not less than T 出口 At that time, T 出口 +a' is determined to be the internal temperature T of the fuel cell stack. 电堆 And a' is the preset threshold a increased to T n Just not less than T 出口 The value at that time.

[0032] This invention also proposes a fuel cell system, wherein the fuel cell system is equipped with a memory and a processor;

[0033] The memory stores computer-readable instructions, which, when executed by the processor, implement the stack temperature prediction method as described above.

[0034] Furthermore, the present invention also proposes a device equipped with a fuel cell, wherein the fuel cell in the device adopts the fuel cell system described above.

[0035] Furthermore, the present invention also proposes a computer-readable storage medium storing a computer program, which, when executed, implements the fuel cell stack temperature prediction method described above.

[0036] The fuel cell system described in this invention, along with the equipment using this fuel cell system and the computer-readable storage medium, has the same beneficial effects compared to the prior art as the aforementioned fuel cell stack temperature prediction method, and will not be repeated here. Attached Figure Description

[0037] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0038] Figure 1 This is a flowchart of the fuel cell stack temperature prediction method described in an embodiment of the present invention;

[0039] Figure 2 This is a flowchart illustrating the process of obtaining the amount n of coolant required to flow through the fuel cell stack according to an embodiment of the present invention;

[0040] Figure 3 This is a flowchart illustrating the determination of the heat transfer coefficient H according to an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram of the structure of the fuel cell stack temperature prediction device according to an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the fuel cell system described in an embodiment of the present invention;

[0043] Explanation of reference numerals in the attached figures:

[0044] 10. Acquisition Module; 20. First Processing Module; 30. Second Processing Module; 40. Determination Module;

[0045] 100. Memory; 200. Processor. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0047] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0048] In the description of this invention, it should be noted that the use of terms such as "upper," "lower," "inner," and "outer," indicating orientation or positional relationship, is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the use of terms such as "first" and "second" is also for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] Furthermore, in the description of this invention, unless otherwise explicitly specified, the connecting structures between mating components can be conventional in the art. Moreover, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0050] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0051] Example 1

[0052] This embodiment relates to a method for predicting the temperature of a fuel cell stack, which is used to estimate the internal temperature of the fuel cell stack to overcome the shortcomings of existing methods that use the inlet and outlet temperatures of the fuel cell stack coolant to determine the internal temperature of the fuel cell stack, and is more conducive to protecting the fuel cell stack.

[0053] In existing technologies, due to factors such as layout process and system cost, it is difficult to place temperature sensors in the stack of a fuel cell system. Furthermore, the construction of a heat transfer model for the stack is also very complex. Therefore, the temperature inside the stack is usually determined by monitoring the inlet and outlet temperatures of the coolant.

[0054] However, once the fuel cell system is running normally, the temperature of the stack body is definitely greater than or equal to the outlet temperature of the stack coolant. At this time, judging whether the internal temperature of the stack is too high based on the inlet and outlet temperatures of the stack coolant is obviously not accurate enough. It is easy for the stack to be damaged due to the actual internal temperature exceeding the limit, which is not conducive to achieving over-temperature protection of the stack.

[0055] Based on this, the fuel cell stack temperature prediction method proposed in this embodiment can estimate the internal temperature of the fuel cell stack based on the coolant outlet temperature, and in its overall design, it combines... Figure 1 As shown, the fuel cell stack temperature prediction method of this embodiment includes the following steps.

[0056] Step s1: Divide the time for the coolant to flow through the fuel cell stack into multiple unit times, and obtain the number of unit times n required for the coolant to flow through the fuel cell stack, and the temperature T of the coolant when it flows out of the fuel cell stack. 出口 .

[0057] In step s1, it should be noted that during actual fuel cell stack operation, the coolant enters through the coolant inlet, travels through the stack over a certain period of time, and reaches the coolant outlet. While flowing through the stack, the coolant exchanges heat with the individual cells within, gaining heat and achieving a temperature increase. To facilitate software calculation and simulation of the entire cooling process, the time it takes for the coolant to flow through the stack can be divided into a series of time slices. Each time slice can be defined as a unit of time; that is, the time for the coolant to flow through the stack can be divided into multiple unit times.

[0058] Thus, the entire coolant heating process can be approximated as follows: A volume of coolant corresponding to one unit of time enters from the fuel cell coolant inlet. In the first unit of time, it gains heat according to the convective heat transfer coefficient and the temperature difference (fuel cell temperature - coolant temperature), and then its temperature rises from T0 to T1. Next, in the second unit of time, the temperature of that volume of coolant changes from T1 to T2, and so on, until that volume of coolant has completely passed through the fuel cell and reached the fuel cell coolant outlet. If the coolant has been flowing for a total of n unit times, then the coolant temperature is T. n This refers to the temperature detected by the temperature sensor at the coolant outlet of the fuel cell stack.

[0059] The term 'n' represents the total time length during which the coolant flows through the fuel cell stack. This time length is determined by the coolant flow rate and the volume of the internal cooling channels of the stack. Assuming the volume of the internal cooling channels is V, the coolant flow rate is m, and the volume of coolant entering the stack per unit time through the coolant inlet is equal to m / ρ, then the total time length t is... total =V*ρ / m, where ρ is the density of the coolant. If one unit is 1 second, then obviously n = t total If a unit of time is 0.1 seconds, then n = t total / 10, and so on.

[0060] However, considering that the coolant flow rate changes during actual operation of the fuel cell stack, and taking into account the actual situation, we can assume that the coolant flow rate per unit time is m0, m1, m2… By calculating for each unit time and summing up m0, m1, m2…, when the total coolant flow rate / ρ is greater than the volume V of the internal cooling channels of the fuel cell stack, it means that the coolant volume per unit time has completely traversed the fuel cell stack and reached the coolant outlet. This point in time is the corresponding t. total And at this time, the coolant outlet temperature of the fuel cell stack is the corresponding T. n .

[0061] Based on the above, combined Figure 2 As shown in the figure, in this embodiment, obtaining the quantity n of coolant required to flow through the fuel cell stack per unit time also includes the following steps:

[0062] Step s11: Obtain the coolant flow rate m per unit time, and get the corresponding coolant volume v from m / ρ.

[0063] Step s12: Accumulate the volume v of coolant corresponding to multiple unit times until the accumulated volume v of coolant is not less than the volume V of the internal cooling channel of the fuel cell stack.

[0064] Step s13: The number of times the accumulated result is exactly not less than the volume V of the cooling channel inside the fuel cell stack is accumulated is determined as the number of unit times n required for the cooling fluid to flow through the fuel cell stack.

[0065] The coolant flow rate m per unit time can be obtained using a flow meter installed at the coolant inlet of the fuel cell stack. However, due to installation difficulties and system cost considerations, fuel cell systems generally do not have a direct coolant flow meter; instead, coolant pressure sensors are typically installed at the coolant inlet and outlet of the fuel cell stack.

[0066] Therefore, given that the pressure difference between the inlet and outlet of the fuel cell stack coolant directly determines the coolant flow rate while the overall structure remains unchanged, and based on the fact that the pressure difference and flow rate of the differential pressure flowmeter are proportional to the square of the pressure difference and flow rate, the following formula can be used. This formula characterizes the relationship between coolant flow rate and the pressure difference between the inlet and outlet of the fuel cell stack coolant. In this formula, Δp is the pressure difference between the inlet and outlet of the fuel cell stack coolant, and Δp = p 进口 -p 出口 Δp max The maximum pressure difference between the inlet and outlet of the fuel cell stack coolant is given by m, where m represents the coolant flow rate. max This represents the maximum flow rate of the fuel cell stack coolant.

[0067] Based on the relationship between the cooling pressure difference and its flow rate, it is clear that this embodiment can be solved using the formula. Obtain the coolant flow rate m per unit time. Furthermore, in practical implementation, the maximum coolant pressure difference Δp during normal stack operation can be obtained experimentally. max Flow rate m at time max .

[0068] Based on the coolant flow rate m obtained above, it can be understood that the coolant volume can also be obtained using the formula v = m / ρ, where the coolant density ρ is determined by the type of coolant.

[0069] It is worth noting that the sum of the coolant volumes *v* is exactly not less than the volume *V* of the internal cooling channels of the fuel cell stack. This means that the sum of the coolant volumes *v* is exactly equal to the volume *V* of the internal cooling channels of the fuel cell stack, or the sum of the coolant volumes *v* is just greater than the volume *V* of the internal cooling channels of the fuel cell stack. Since this embodiment is for estimating the internal temperature of the fuel cell stack, it is understandable that even if the sum of the coolant volumes *v* is slightly greater than the volume *V* of the internal cooling channels of the fuel cell stack, it is still acceptable.

[0070] Additionally, it should be noted that in practical implementation, the volume V of the internal cooling channels of the fuel cell stack can be obtained through measurement, and the volume V is usually a fixed value, with negligible changes during stack operation. Furthermore, when determining the volume V of the internal cooling channels, the pipe volumes at the coolant inlet and outlet of the fuel cell stack should be excluded, as the coolant can only transfer heat with individual cells when it is inside the fuel cell stack.

[0071] In this embodiment, during specific implementation, the temperature T of the coolant flowing out of the fuel cell stack is... 出口 The temperature can be obtained through a temperature sensor located at the fuel cell coolant outlet. The coolant pressure p at the fuel cell coolant inlet... 进口 The coolant pressure p at the fuel cell stack coolant outlet出口 The pressure can be obtained by pressure sensors installed at the inlet and outlet of the fuel cell stack coolant, respectively. The coolant inlet pressure p is then obtained. 进口 Coolant outlet pressure p 出口 At that time, the pressure difference between the coolant inlet and outlet is the pressure difference Δp between the fuel cell coolant inlet and outlet.

[0072] Step s2: Set the internal temperature T of the fuel cell stack. 电堆 =T 出口 +a, and starting from n=1, substitute into the formula sequentially: H*(T) 电堆 -T n-1 )=c*m*(T n -T n-1 ), until T is calculated. n .

[0073] Where a is a preset threshold greater than 0, H is the heat transfer coefficient and represents the heat transferred per unit temperature difference per unit time, c is the specific heat capacity of the coolant, m is the mass of the coolant in the first unit time, and when n=1, T0 represents the temperature of the coolant when it enters the fuel cell stack in the first unit time.

[0074] In step s2, it should be noted that the coolant enters the fuel cell stack through the coolant inlet. The heat generated by the single-cell reaction within the stack is transferred to the coolant and carried away by the coolant. The total heat carried away by the coolant is generally related to the heat exchange coefficient, the stack body temperature, the coolant inlet temperature, the coolant flow rate, and the residence time of the coolant inside the stack. Therefore, when estimating the internal temperature of the fuel cell stack, the above factors need to be considered. Among these, the heat exchange coefficient is a relatively complex factor, and its reasonableness needs to be ensured as much as possible to improve the accuracy of the estimation.

[0075] Specifically, during fuel cell operation, the heat generated by each cell in the fuel cell stack is transferred to the flowing coolant. In this heat transfer scenario, the individual cells are considered solids and the coolant is considered a liquid. According to Newton's law of cooling, we have: Q = A * h * dT, where Q represents heat in W and A represents the contact area in m². 2 h represents the convective heat transfer coefficient, with units of W / (m²). 2 ·K), dT represents the temperature difference between the solid and the liquid, and the unit is K.

[0076] Clearly, the aforementioned convective heat transfer coefficient characterizes the heat transferred per unit temperature difference and per unit area (i.e., the energy transferred per unit time, in J). However, since the convective heat transfer coefficient is related to the types of solids and liquids in contact, the internal convective motion of the liquid, and the liquid flow velocity, and since the contact area between the coolant and the individual cell per unit time in the fuel cell stack is uncertain, these factors are difficult to define precisely. Therefore, to simplify the problem, in this embodiment, when estimating the stack temperature, the heat transfer coefficient h and the contact area A can be combined into a single parameter H. This parameter H represents the heat transfer coefficient, with units of W / K, and thus characterizes the heat transferred per unit temperature difference per unit time.

[0077] By fusing to form a new heat transfer coefficient H, the above formula can be transformed into: Q = H * dT. Furthermore, regarding this heat transfer coefficient H, in this embodiment, it can be determined, for example, in the following way, combined with... Figure 3 As shown, the determination method includes the following steps:

[0078] Step s21: Construct the experimental fuel cell stack and put it into operation.

[0079] Step s22: Control the time for the coolant to flow through the experimental fuel cell stack to be z units of time, and record the temperature T of the coolant outlet of the experimental fuel cell stack after z units of time. z And the temperature T of the experimental fuel cell stack body. 电堆本体 .

[0080] Step s23: Maintain the temperature of the coolant entering the experimental fuel cell stack, and the temperature T of the experimental fuel cell stack itself. 电堆本体 Keeping the flow rate of the coolant flowing through the experimental fuel cell stack constant, the flow time of the coolant through the stack is increased to z-1 unit time, and the outlet temperature T of the coolant at the experimental fuel cell stack is recorded after z-1 unit time. z-1 .

[0081] Step s24, using the formula: The heat transfer coefficient H is calculated, where c is the specific heat capacity of the coolant, and m is the heat transfer coefficient. 单位时间 This refers to the mass of coolant per unit time.

[0082] Specifically, the experimental fuel cell stack can use fewer single cells (e.g., 7 cells) compared to the actual fuel cell stack. The experimental fuel cell stack should also be equipped with an outer shell to make its structure consistent with that of the real fuel cell stack. At the same time, the experimental fuel cell stack should also be equipped with sensors to monitor the inlet and outlet temperatures of the coolant, the flow rate of the coolant, and the temperature of the fuel cell stack itself.

[0083] The aforementioned monitoring of coolant inlet and outlet temperatures and coolant flow rate can be achieved, for example, by using pressure sensors and flow meters installed at the coolant inlet and outlet positions on the experimental fuel cell stack. The aforementioned monitoring of the fuel cell stack body temperature can be achieved, for example, by using temperature sensors such as patch thermocouples installed at individual cells within the fuel cell stack, in order to obtain the temperature of the fuel cell stack body as effectively as possible.

[0084] It should be noted that after the experimental fuel cell stack is in operation, the temperature parameters mentioned above should be recorded when each part of the fuel cell stack reaches a relatively stable state. In this stable state, for example, the inlet and outlet temperatures of the coolant in the fuel cell stack and the temperature of the fuel cell stack body are basically unchanged, or only vary within a small range.

[0085] Furthermore, when determining the heat transfer coefficient H using an experimental fuel cell stack, it is difficult to ensure that the coolant flows through the stack precisely within a given time. This would result in excessively high coolant flow rates and excessively short time intervals, easily leading to significant errors. Additionally, this scenario differs considerably from the actual operating conditions of the fuel cell stack, also causing deviations. Therefore, it is preferable to operate the experimental fuel cell stack in a medium-to-high power mode. This medium-to-high power mode can be referenced from the relevant modes in actual fuel cell stacks. The power of the fuel cell stack in the medium-to-high power mode is typically 60%-80% of the standard power of the fuel cell system. For example, in a fuel cell system with a standard power of 120 kW, the power of the medium-to-high power module is between 72 kW and 96 kW. Moreover, since fuel cell stacks often experience overheating in medium-to-high power mode during actual operation, setting the experimental fuel cell stack to operate in this mode also improves the application effectiveness of the estimation method described in this embodiment.

[0086] When determining the heat transfer coefficient H using an experimental fuel cell stack, in the medium-to-high power mode, the time taken for the coolant to flow through the stack is, for example, z unit times. Once the relevant temperature data stabilizes, the temperature T at the coolant outlet of the experimental fuel cell stack after z unit times can be calculated. z And the temperature T of the experimental fuel cell stack body. 电堆本体 The record is then made. Next, the coolant pump speed is slightly increased so that the coolant flows through the fuel cell stack for z-1 unit times. Once the relevant temperature data stabilizes, the temperature T at the coolant outlet of the experimental fuel cell stack is recorded after z-1 unit times. z-1 .

[0087] Among them, when performing the above-mentioned temperature T z-1When obtaining the temperature of the coolant entering the experimental fuel cell stack, the temperature can be kept constant, for example, by using a combination of radiators and heaters installed in the cooling circuit and employing closed-loop control. Alternatively, as a simpler method, the cooling circuit of the fuel cell stack can be made unidirectional during the experiment, and a large volume of coolant at a constant temperature can be prepared using a large-volume coolant storage container to ensure that the temperature of the coolant entering the fuel cell stack remains constant. As for the temperature T of the experimental fuel cell stack itself... 电堆本体 For example, the power point of the fuel cell stack can be kept constant, and the temperature T of the fuel cell stack body can be maintained by controlling the gas intake at the anode and cathode. 电堆本体 constant.

[0088] After obtaining the above temperature T z Temperature T 电堆本体 and temperature T z-1 Then, according to the aforementioned modified formula, the obtained temperature parameters can be substituted to obtain: Q 单位时间 =H*(T 电堆本体 -T z-1 This formula expresses the heat absorbed by the coolant in the last unit of time. Since this heat also causes the coolant temperature to rise, according to the formula for specific heat capacity, Q... 吸 =c*m*(T 末温 -T 初温 Then we can obtain: Q 单位时间 =c*m 单位时间 *(T z -T z-1 ), where m 单位时间 The flow rate count is the value recorded when the coolant takes z units of time to flow through the fuel cell stack, which is also the mass of coolant per unit time.

[0089] Based on the above formula, we can further obtain: H*(T) 电堆本体 -T z-1 )=c*m 单位时间 *(T z -T z-1 Therefore, the heat transfer coefficient H can also be obtained through... Calculated.

[0090] It is worth noting that the heat transfer coefficient H, which characterizes the heat transferred per unit temperature difference per unit time, also characterizes the heat absorbed by the mass of coolant per unit temperature difference per unit time. Here, the heat transfer coefficient H incorporates the concept of area. Furthermore, since the main difference between the experimental fuel cell stack and the real fuel cell stack lies in the number of individual cells, while the internal structure of each individual cell is identical and the contact surface between each individual cell and the coolant is consistent, it can be determined that the heat transfer coefficient H obtained from the experimental fuel cell stack can be applied to the real fuel cell stack.

[0091] Step s3: Compare the calculated T n With T 出口 and in T n Less than T 出口 At that time, the preset threshold 'a' is increased successively, and after each increase of the preset threshold 'a', the process restarts from n=1, using the formula: H*(T 电堆 -T n-1 )=c*m*(T n -T n-1 Calculate T n Until the preset threshold a increases to the level that makes the calculated T n Just not less than T 出口 .

[0092] In step s3, as a preferred embodiment, the preset threshold a can be a natural number greater than 0, so that the preset threshold a is an integer, which can simplify the design workload and related computational load without affecting the effectiveness of the internal temperature prediction of the fuel cell.

[0093] Furthermore, since the temperature inside the fuel cell stack is often higher than the temperature at the coolant outlet, the internal temperature T of the fuel cell stack can be set as a certain value when making estimations. 电堆 =T 出口 +a. Furthermore, by substituting into the formula H*(T)... 电堆 -T n-1 )=c*m*(T n -T n-1 ) Calculate, T n Less than T 出口 This means that the coolant has not yet reached the fuel cell stack coolant outlet within that unit of time. Of course, if T n Not less than T 出口 This indicates that the coolant has reached the fuel cell coolant outlet for that unit of time.

[0094] Taking 'a' as a positive integer as an example, in the initial calculation, T... 电堆 =T 出口 +1, and when n=1, it can be obtained through the formula H*(T) 电堆T1 is calculated using the formula H*(T0) = c*m*(T1-T0), and then the calculated T1 is substituted into the formula, i.e., H*(T0) = c*m*(T1-T0). 电堆 T2 can be calculated by ∠T1 = c*m*(T2-T1), and this calculation is repeated until T is obtained. n Then, in T n Less than T 出口 When, T can be set 电堆 =T 出口 +2, and repeat the above iterative calculation process until T is obtained. n Just not less than T 出口 .

[0095] Step s4, in the calculated T n Just not less than T 出口 At that time, T 出口 +a' is determined to be the internal temperature T of the fuel cell stack. 电堆 .

[0096] In step s4, a' is the preset threshold a increasing to T. n Just not less than T 出口 The value at that time, and at the same time, for example, assuming that the preset threshold a in step s3 increases to the value k, then the temperature T inside the stack 电堆 =T 出口 +k.

[0097] In addition, regarding the calculated T n Just not less than T 出口 Similarly, it also includes the calculated T. n Just with T 出口 Equal, or the calculated T n Just satisfying greater than T 出口 Furthermore, it is understood that for the estimation of the internal temperature of the fuel cell stack in this embodiment, even if the calculated T... n Slightly greater than T 出口 That is acceptable.

[0098] In this embodiment, the above steps enable the estimation of the internal temperature of the fuel cell stack based on the coolant outlet temperature. Furthermore, it should be noted that the specific calculation for estimating the internal temperature of the fuel cell stack is performed after the coolant has passed through the fuel cell stack within a unit of time, at which point the coolant outlet temperature T is detected and obtained. 出口 This refers to the outlet temperature of the coolant. In practice, it's also common practice to periodically calculate the internal temperature of the fuel cell stack using relevant software, continuously refining the calculations to obtain the latest estimated internal temperature value.

[0099] Of course, it should also be noted that, in practical applications, to obtain better prediction results, the above-described estimation method in this embodiment should avoid significant load increases and decreases at high power points in the fuel cell stack, as this would cause large-scale fluctuations in the internal temperature of the stack, affecting the accuracy of the estimation. Furthermore, since fuel cell stacks are sealed with an outer casing, and overheating generally occurs after the system has been running for a certain period, it can be assumed that the overall temperature distribution of the fuel cell stack is relatively uniform after a period of operation, and will not affect the application effect of the estimation method in this embodiment.

[0100] The fuel cell stack temperature prediction method in this embodiment, with the above design, can estimate the internal temperature of the fuel cell stack based on the outlet temperature of the fuel cell stack coolant. Compared with the method of judging by the inlet and outlet temperatures of the fuel cell stack coolant, it can obtain a more reasonable internal temperature of the fuel cell stack, which is beneficial to better protect the fuel cell stack and has good practicality.

[0101] Furthermore, regarding the results predicted by the method described above in this embodiment, the internal temperature of the experimental fuel cell will be estimated using the method of this embodiment, and compared with the actual temperature of the fuel cell body collected in the experimental fuel cell multiple times. The inventors also found that the difference between the two is within the allowable range (less than 5%), which makes the fuel cell temperature prediction method of this embodiment relatively reliable and able to meet the requirements of effective judgment of the internal temperature of the fuel cell, so as to better realize the over-temperature protection of the fuel cell.

[0102] Example 2

[0103] This embodiment relates to a fuel cell stack temperature prediction device, which is based on the fuel cell stack temperature prediction method in Embodiment 1 above, and combines with... Figure 4 As shown, the device includes an acquisition module 10, a first processing module 20, a second processing module 30, and a determination module 40.

[0104] The acquisition module 10 is used to divide the time for the coolant to flow through the fuel cell stack into multiple unit times, and to acquire the number of unit times n required for the coolant to flow through the fuel cell stack, and the temperature T of the coolant when it flows out of the fuel cell stack. 出口 .

[0105] The first processing module 20 is used to set the internal temperature T of the fuel cell stack. 电堆 =T 出口 +a, and starting from n=1, substitute into the formula sequentially: H*(T) 电堆 -T n-1 )=c*m*(T n -T n-1 ), until T is calculated. nWhere a is a preset threshold greater than 0, H is the heat transfer coefficient and represents the heat transferred per unit temperature difference per unit time, c is the specific heat capacity of the coolant, m is the mass of the coolant in the first unit time, and when n=1, T0 represents the temperature of the coolant when it enters the fuel cell stack in the first unit time.

[0106] The second processing module 30 is used to compare the calculated T. n With T 出口 and in T n Less than T 出口 At that time, the preset threshold 'a' is increased successively, and after each increase of the preset threshold 'a', the process restarts from n=1, using the formula: H*(T 电堆 -T n-1 )=c*m*(T n -T n-1 Calculate T n Until the preset threshold a increases to the level that makes the calculated T n Just not less than T 出口 The determination module 40 is used to determine the calculated T. n Just not less than T 出口 At that time, T 出口 +a' is determined to be the internal temperature T of the fuel cell stack. 电堆 And a' is a preset threshold a increases to T n Just not less than T 出口 The value at that time.

[0107] In the stack temperature prediction device of this embodiment, in specific implementation, the above-mentioned modules can be existing module products with data transmission, storage or computing functions. Furthermore, the above modules in this embodiment can be set up separately, or preferably, they can be integrated into the controller of the fuel cell system.

[0108] Meanwhile, when the modules described above in this embodiment are working, the acquisition of parameters such as the temperature, pressure, and flow rate of the coolant flowing through the fuel cell stack can be found in the relevant description in Embodiment 1. In specific applications, the process by which the fuel cell stack temperature prediction device in this embodiment predicts the internal temperature of the fuel cell stack can also be found in the relevant description in Embodiment 1, and will not be repeated here.

[0109] Example 3

[0110] This embodiment relates to a fuel cell system, combined with... Figure 5 As shown, the fuel cell system includes a memory 100 and a processor 200.

[0111] The memory 100 stores computer-readable instructions, which, when executed by the processor 200, enable the fuel cell temperature prediction method in Embodiment 1.

[0112] In specific implementation, the structure of the fuel cell system in this embodiment can refer to existing fuel cell systems, and the memory 100 and processor 200 can generally be integrated into the controller of the fuel cell system.

[0113] Furthermore, this embodiment also relates to a device equipped with a fuel cell, and the fuel cell in the device adopts the above-described fuel cell system.

[0114] Specifically, the device equipped with a fuel cell in this embodiment can be, for example, a fixed electrical device, such as a fuel cell power generation device. Of course, in addition to being a fixed electrical device, the device in this embodiment can also be a mobile transportation device, such as a fuel cell vehicle, etc., and there is no limitation on this.

[0115] Example 4

[0116] This embodiment relates to a computer-readable storage medium storing a computer program, which, when executed, implements the fuel cell stack temperature prediction method in Embodiment 1.

[0117] In this embodiment, the computer-readable storage medium is generally exemplified by a storage module. Furthermore, the computer-readable storage medium includes both permanent and non-permanent, removable and non-removable media, which can be used to store information by any existing method or technology.

[0118] The aforementioned information may be computer-readable instructions, data structures, program modules, or other data. Examples of computer-readable storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or other memory technologies, CD-ROM, digital versatile optical disc (DVD), or other optical storage, magnetic tape, magnetic magnetic tape, disk storage, or other magnetic storage devices, or any other non-transfer medium that can be used to store information that can be accessed by a computing device.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for predicting fuel cell stack temperature, characterized in that, The method includes: The time it takes for the coolant to flow through the fuel cell stack is divided into multiple unit times, and the number of unit times n required for the coolant to flow through the fuel cell stack and the temperature T of the coolant when it flows out of the fuel cell stack are obtained. 出口 ; Set the internal temperature T of the fuel cell stack. 电堆 =T 出口 +a, and starting from n=1, substitute into the formula sequentially: H*(T) 电堆 -T n-1 )=c*m*(T n -T n-1 ), until T is calculated. n Where a is a preset threshold greater than 0, H is the heat transfer coefficient and represents the heat transferred per unit temperature difference per unit time, c is the specific heat capacity of the coolant, m is the mass of the coolant in the first unit time, and when n=1, T0 represents the temperature of the coolant when it enters the fuel cell stack in the first unit time. Compare the calculated T n With T 出口 and in T n Less than T 出口 At that time, the preset threshold 'a' is increased successively, and after each increase of the preset threshold 'a', the process restarts from n=1, using the formula: H*(T 电堆 -T n-1 )=c*m*(T n -T n-1 Calculate T n Until the preset threshold a increases to the level that makes the calculated T n Just not less than T 出口 ; In the calculated T n Just not less than T 出口 At that time, T 出口 +a′ is determined to be the internal temperature T of the fuel cell stack. 电堆 And a′ is the preset threshold a increased to T n Just not less than T 出口 The value at that time.

2. The method for predicting the temperature of a fuel cell stack according to claim 1, characterized in that, The acquisition of the quantity n of unit time required for the coolant to flow through the fuel cell stack includes: Obtain the coolant flow rate m per unit time, and get the corresponding coolant volume v from m / ρ, where ρ is the density of the coolant; The volume v of coolant corresponding to multiple unit times is accumulated until the accumulated volume v of coolant is exactly not less than the volume V of the cooling channel inside the fuel cell stack. The number of times the accumulated result is exactly not less than the volume V of the cooling channel inside the fuel cell is accumulated is determined as the number of unit times n required for the cooling fluid to flow through the fuel cell.

3. The method for predicting the temperature of a fuel cell stack according to claim 2, characterized in that: Through formula Obtain the coolant flow rate m per unit time, where Δp is the pressure difference between the coolant inlet and outlet of the fuel cell stack. max The maximum pressure difference between the inlet and outlet of the fuel cell stack coolant, m max This represents the maximum flow rate of the fuel cell stack coolant.

4. The method for predicting the temperature of a fuel cell stack according to claim 1, characterized in that, The heat transfer coefficient H is determined in the following manner: Construct an experimental fuel cell stack and put it into operation; The coolant flow time through the experimental fuel cell stack is controlled to be z unit time, and the temperature T of the coolant outlet of the experimental fuel cell stack is recorded after z unit time. z And the temperature T of the experimental fuel cell stack body. 电堆本体 ; Maintain the temperature of the coolant entering the experimental fuel cell stack, and the temperature T of the experimental fuel cell stack body. 电堆本体 The flow rate of the coolant flowing through the experimental fuel cell stack is increased while keeping the flow rate constant. The time for the coolant to flow through the experimental fuel cell stack is controlled to be z-1 unit time, and the temperature T at the outlet of the coolant of the experimental fuel cell stack is recorded after z-1 unit time. z-1 ; Through the formula: The heat transfer coefficient H is calculated, where c is the specific heat capacity of the coolant, and m... 单位时间 This refers to the mass of coolant per unit time.

5. The method for predicting the temperature of a fuel cell stack according to claim 4, characterized in that: The experimental fuel cell stack operates in a medium-to-high power mode.

6. The method for predicting the temperature of a fuel cell stack according to any one of claims 1 to 5, characterized in that: The preset threshold a is a natural number greater than 0.

7. A device for predicting the temperature of a fuel cell stack, characterized in that: It includes an acquisition module (10), a first processing module (20), a second processing module (30), and a determination module (40); The acquisition module (10) is used to divide the time for the coolant to flow through the fuel cell stack into multiple unit times, and to acquire the number n of unit times required for the coolant to flow through the fuel cell stack, and the temperature T of the coolant when it flows out of the fuel cell stack. 出口 ; The first processing module (20) is used to set the internal temperature T of the fuel cell stack. 电堆 =T 出口 +a, and starting from n=1, substitute into the formula sequentially: H*(T) 电堆 -T n-1 )=c*m*(T n -T n-1 ), until T is calculated. n Where a is a preset threshold greater than 0, H is the heat transfer coefficient and represents the heat transferred per unit temperature difference per unit time, c is the specific heat capacity of the coolant, m is the mass of the coolant in the first unit time, and when n=1, T0 represents the temperature of the coolant when it enters the fuel cell stack in the first unit time. The second processing module (30) is used to compare the calculated T n With T 出口 and in T n Less than T 出口 At that time, the preset threshold 'a' is increased successively, and after each increase of the preset threshold 'a', the process restarts from n=1, using the formula: H*(T 电堆 -T n-1 )=c*m*(T n -T n-1 Calculate T n Until the preset threshold a increases to the level that makes the calculated T n Just not less than T 出口 ; The determining module (40) is used to determine the calculated T n Just not less than T 出口 At that time, T 出口 +a′ is determined to be the internal temperature T of the fuel cell stack. 电堆 And a′ is the preset threshold a increased to T n Just not less than T 出口 The value at that time.

8. A fuel cell system, characterized in that: The fuel cell system includes a memory (100) and a processor (200); The memory (100) stores computer-readable instructions, which, when executed by the processor (200), implement the fuel cell temperature prediction method according to any one of claims 1 to 6.

9. A device equipped with a fuel cell, characterized in that: The fuel cell installed in the device is the fuel cell system described in claim 8.

10. A computer-readable storage medium, characterized in that, The readable storage medium stores a computer program that, when executed, implements the fuel cell stack temperature prediction method according to any one of claims 1-6.

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