Distributed HT-PEMFC stack with synergistic thermal management for aircraft

Abstract

The application discloses a distributed HT-PEMFC stack with heat generation and dissipation synergic thermal management for aircraft, comprising: a plurality of small-power HT-PEMFC stacks; a heat dissipation assembly, the heat dissipation assembly comprising an air inlet grille, an air inlet duct, a heat dissipation fan, an air outlet duct and an air outlet; a sensor assembly, the sensor assembly comprising a temperature sensor and a flow sensor; and a central control system, the central control system being used for controlling, including but not limited to, the HT-PEMFC stack power output size, the air inlet grille opening area size, the grille air inlet duct position, the fan power size and position and the redistribution of the stack output power at different positions. According to the application, the stack can realize heat generation and dissipation synergic regulation and control, reduce parasitic power, prolong the service life of the stack and realize the light weight of the aircraft.

Description

Technical Field

[0001] This invention relates to the technical field of battery materials, and in particular to a distributed HT-PEMFC stack for aircraft with heat dissipation and heat generation synergistic thermal management. Background Technology

[0002] In recent years, high-temperature proton exchange membrane fuel cell systems have attracted increasing attention. Compared with low-temperature PEMFC systems, high-temperature PEMFC systems have advantages such as fast reaction kinetics, strong CO resistance, and simpler hydrothermal management. Their operating temperature is generally 100℃-200℃.

[0003] Currently, HT-PEMFC stacks suffer from a fatal flaw: short lifespan. Ji Feng et al. mentioned in their paper "Stability Analysis and Optimization of High-Temperature Proton Exchange Membrane Fuel Cell Stacks" that for 100-watt air-cooled HT-PEMFC stacks, the rapid loss of phosphoric acid from single cells in the middle of the stack is the main reason for the shortened stack lifespan. Uneven temperature distribution in the stack is the main reason for the rapid loss of phosphoric acid. Therefore, promoting uniform temperature distribution is the main design consideration in order to extend the stack lifespan.

[0004] In addition, the high speed of the aircraft greatly increases the air velocity. How to utilize high-speed air to realize a passive air-cooling strategy for high-power HT-PEMFC stacks is a feasible direction to maintain the temperature of HT-PEMFC stacks with lower power consumption and thus improve the power density of HT-PEMFC systems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a distributed HT-PEMFC fuel cell stack for aircraft with coordinated heat generation and dissipation thermal management, achieving coordinated control of heat generation and dissipation, reducing parasitic power, extending stack lifespan, and enabling lightweight aircraft design. To achieve the above objectives and other advantages, the present invention provides a distributed HT-PEMFC fuel cell stack for aircraft with coordinated heat generation and dissipation thermal management, comprising:

[0006] Several low-power HT-PEMFC fuel cell stacks;

[0007] A heat dissipation assembly, comprising an air intake grille, an air intake duct, a cooling fan, an exhaust duct, and an exhaust port;

[0008] The sensor assembly includes a temperature sensor and a flow sensor;

[0009] The central control system is used to control, but is not limited to, the power output of the HT-PEMFC stack, the opening area of ​​the air intake grille, the position of the grille air intake, the power and position of the fan, and the redistribution of the stack output power at different positions.

[0010] Preferably, the temperature sensor is used to detect the temperature magnitude and distribution of the fuel cell at different locations within the cavity and to detect the temperature of the cooling gas at the air inlet.

[0011] Preferably, the flow sensor is used to detect the flow rate of cooling gas at the air inlet.

[0012] Preferably, the central control system is used to receive temperature signals transmitted by temperature sensors inside the cavity and at the air inlet, and cooling gas flow signals transmitted by the air inlet flow sensor.

[0013] A method for controlling the coordinated thermal management of heat generation and dissipation in a distributed HT-PEMFC fuel cell stack for aircraft, comprising:

[0014] During the initial stage of takeoff, the fan position and power are adjusted according to the temperature distribution gradient and size of the fuel cell stack by maintaining the grid at its maximum opening.

[0015] During the flight phase of the aircraft, temperature and heat dissipation are adjusted using the first and / or second adjustment schemes, as detailed below:

[0016] Determine whether both the first and second adjustment schemes exist simultaneously. If it is determined that neither of the two adjustment schemes exists, then execute either the first or the second adjustment scheme.

[0017] If it is determined that there are two adjustment schemes, it is further determined whether the difference between the different adjustment parameters of the two adjustment schemes is within the corresponding preset range. If it is determined to be yes, the second adjustment scheme is implemented; if it is determined to be no, the parameters whose difference between the first adjustment scheme and the second adjustment scheme does not meet the requirements are adjusted until the difference meets the pre-approval range value.

[0018] After the above steps, it is further determined whether the temperature of the fuel cell stack meets the requirements. If it does, the process ends; otherwise, adjustments are made.

[0019] Preferably, the first adjustment scheme is as follows:

[0020] The system detects whether the temperature gradient of the fuel cell stack exceeds the set value. If it does not exceed the set value, no adjustment is needed. If it exceeds the set value, the system calculates the optimal scheme for the redistribution of fan power, position, grille opening size, grille air inlet position, and fuel cell stack output power at different positions based on the magnitude of the temperature gradient, the flow rate and temperature of the cooling gas at the grille inlet, to achieve the temperature uniformity requirement and ensure that the sum of the output power of each fuel cell stack meets the current fuel cell stack output power requirement.

[0021] Preferably, the second adjustment scheme is as follows:

[0022] Check whether the upper and lower limits of the fuel cell stack temperature exceed the set values;

[0023] If the set value is not exceeded, no adjustment is required; if the set value is exceeded, the optimal scheme for redistributing the output power of the fuel cell stack at different locations is calculated based on the magnitude of the abnormal temperature of the stack, the flow rate and temperature of the cooling gas at the grid inlet, the fan power, position, grid opening size, grid air inlet position, and the redistribution of the output power of the stack at different locations, so as to meet the extreme temperature control requirements and ensure that the sum of the output power of each stack meets the current output power requirements of the fuel cell stack.

[0024] Compared with the prior art, the beneficial effects of this invention are:

[0025] (1) By controlling power output in a distributed manner, energy utilization efficiency can be improved and waste hydrogen emissions can be reduced.

[0026] (2) Actively control the output power of a single fuel cell stack, control the temperature distribution uniformly from the perspective of heat source, and realize the coordinated regulation of heat generation and heat dissipation.

[0027] (3) It facilitates heat dissipation of individual fuel cells, reduces individual temperature gradients, promotes uniform temperature distribution, inhibits excessive loss of phosphoric acid, and extends the service life of fuel cells.

[0028] (4) By making full use of the high speed of the aircraft, a passive air-cooling strategy is implemented in some flight phases to reduce the power consumption for maintaining the temperature of the HT-PEMFC stack and improve the power density of the HT-PEMFC system.

[0029] (5) Eliminates auxiliary equipment such as coolant and circulation pump in traditional high-temperature proton exchange membrane fuel cell systems, reduces parasitic power, increases specific power, and at the same time reduces system weight, further realizing the lightweighting of the fuel cell. Attached Figure Description

[0030] Figure 1 The flowchart illustrates the heat dissipation coordinated thermal management control method for a distributed HT-PEMFC fuel cell stack for aircraft with heat dissipation coordinated thermal management according to the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] A distributed HT-PEMFC fuel cell stack for aircraft with integrated heat dissipation and thermal management includes: several low-power HT-PEMFC stacks; the HT-PEMFC stacks are placed inside the cavity in an attitude that maximizes contact with the cooling air flowing into the cavity; and the power output of the several low-power HT-PEMFC stacks is individually controlled by a central control system.

[0033] The heat dissipation assembly includes an air intake grille, an air intake duct, a cooling fan, an exhaust duct, and an exhaust port. The opening area of ​​the air intake grille affects the amount of air intake. When the air intake velocity of the air intake grille is less than a critical velocity, the air intake grille maintains its maximum opening area, and heat dissipation is entirely handled by the cooling fan. When the air intake velocity of the air intake grille is greater than or equal to the critical velocity, the cooling fan stops operating, and the central control system controls the opening area of ​​the air intake grille to achieve heat dissipation. The critical velocity can be determined by various methods; one method is given below as an example.

[0034] The energy balance equation within a fuel cell stack can be expressed as follows:

[0035] q theo =q elec +q sens +q cool #(1)

[0036] In the formula: q theo q represents the energy theoretically generated by the electrochemical reaction in a fuel cell, expressed in kW. elec The electrical energy generated by the fuel cell, kW; q sens The sensible heat (kW) is the energy required to convert the temperature of the fluid in the fuel cell stack to its standard temperature. cool The heat generated in the fuel cell by air removal is expressed in kW.

[0037] q theo The calculation formula is

[0038]

[0039] In the formula: The mass flow rate of hydrogen consumed in the reaction of the fuel cell stack is kg / s; ΔH represents the molar mass of hydrogen, in kg / mol; rxn This is the enthalpy change during the hydrogen reaction in the electrochemical reaction. Under standard conditions, this value is 285.8 kJ / mol.

[0040] q elec The calculation formula is

[0041]

[0042] In the formula: n is the number of individual cells in the fuel cell stack; Vfc V is the output voltage of the fuel cell stack; A is the load current of the fuel cell stack.

[0043] Sensible heat q of the anode fluid in a fuel cell stack sens,an and the sensible heat q of the cathode fluid sens,ca The calculation formulas are respectively

[0044]

[0045] In the formula: The hydrogen mass flow rate at the anode outlet is kg / s; W w,g,an,out The mass flow rate of water vapor at the anode outlet is kg / s; The mass flow rate of hydrogen at the anode inlet is kg / s; W w,g,an,in The mass flow rate of steam at the anode inlet is kg / s; is the specific heat capacity of hydrogen, kJ / (kg·K); Specific heat capacity of water vapor, kJ / (kg·K); T an,out The anode outlet temperature is K; T an,in The anode inlet temperature is K; T atm The ambient temperature, in K; The oxygen mass flow rate at the cathode outlet is kg / s; The specific heat capacity of oxygen is kJ / (kg·K); W w,g,ca,out The mass flow rate of water vapor at the cathode outlet is kg / s; The nitrogen mass flow rate at the cathode outlet is kg / s; The specific heat capacity of nitrogen is kJ / (kg·K); The oxygen mass flow rate at the cathode inlet is kg / s; W w,g,ca,in The mass flow rate of steam at the cathode inlet is kg / s; T represents the mass flow rate of nitrogen gas at the cathode inlet, in kg / s. ca,out Cathode outlet temperature, K; T ca,in The cathode inlet temperature is K.

[0046] q sens The calculation formula is

[0047] q sens =q sens,an +q sens,ca #(6)

[0048] q cool The calculation formula is

[0049] q cool =W ari,in C p,ari (T fc -T air,in)#(7)

[0050]

[0051] In the formula: W ari,in Cooling air flow rate, kg / s; T air,in The temperature at which cooling air enters the reactor is K; T fc The temperature of the fuel cell stack is K; m st The mass of the fuel cell stack is expressed in kg; C p,st The average specific heat capacity of HT-PEMFC; C p,air The average specific heat capacity of the current air (kJ / (kg·K)).

[0052] Therefore, from equations (1) to (8), the heat q generated in the fuel cell by the air can be obtained. cool That is, the amount of heat that the air should absorb.

[0053] At this time, the volumetric flow rate V of the air air (m 3 The formula for calculating / h) is:

[0054]

[0055] Where, ρ air The air density in the space where the aircraft is currently located (kg / m³) 3 ). T air,out This refers to the temperature at which the cooling air exits the reactor.

[0056] The air velocity v in the space where the HT-PEMFC is located air The formula for calculation is:

[0057]

[0058] Among them, A rad,air The area (m²) for heat exchange between cooling air and HT-PEMFC 2 ).

[0059] The sensor assembly includes a temperature sensor and a flow sensor;

[0060] The central control system is used to control, but is not limited to, the power output of the HT-PEMFC fuel cell stack, the opening area of ​​the air intake grille, the position of the grille air intake duct, the power and position of the fan, and the redistribution of the fuel cell stack output power at different positions. The central control system also receives temperature signals from temperature sensors within the cavity and at the air intake, as well as cooling gas flow signals from the air intake flow sensor. When the temperature within the cavity is uneven, the central control system can simultaneously control the working output of the fuel cell stack at different positions, as well as the opening area of ​​the air intake grille, the position of the grille air intake duct, and the power and position of the fan, achieving coordinated regulation of heat generation and dissipation, and controlling the temperature magnitude and distribution gradient.

[0061] The temperature sensor is used to detect the temperature magnitude and distribution of the fuel cell at different locations within the cavity and to detect the temperature of the cooling gas at the air inlet.

[0062] The flow sensor is used to detect the flow rate of cooling gas at the air inlet.

[0063] In this application, heat generation refers to the residual heat generated during the operation of the fuel cell stack, and heat dissipation refers to air cooling; and heat dissipation is accomplished by the combination of a cooling fan and an air intake grille.

[0064] A heat dissipation coordinated thermal management control method for a distributed HT-PEMFC fuel cell stack for aircraft with heat dissipation coordinated thermal management includes:

[0065] During the initial takeoff phase, the fan position and power are adjusted based on the temperature distribution gradient and magnitude of the fuel cell stack, maintaining the grid opening at its maximum. During this phase, the cooling gas flow rate at the air inlet is relatively slow, relying on the fan for air cooling. The fan position and power are adjusted based on the temperature distribution gradient and magnitude of the fuel cell stack. Temperature sensors monitor the temperature distribution gradient and magnitude of the fuel cell stack within the cavity in real time, while flow and temperature sensors monitor the inflow rate and temperature of the gas at the grid inlet in real time.

[0066] During the flight phase of the aircraft, temperature and heat dissipation are adjusted using the first and / or second adjustment schemes, as detailed below:

[0067] Determine whether both the first and second adjustment schemes exist simultaneously. If it is determined that neither of the two adjustment schemes exists, then execute either the first or the second adjustment scheme.

[0068] If it is determined that there are two adjustment schemes, it is further determined whether the difference between the different adjustment parameters of the two adjustment schemes is within the corresponding preset range. If it is determined to be yes, the first adjustment scheme and the second adjustment scheme are implemented; if it is determined to be no, the parameters in the first adjustment scheme and the second adjustment scheme that do not meet the requirements are adjusted until the difference meets the pre-approval range value.

[0069] After the above steps, it is further determined whether the temperature of the fuel cell stack meets the requirements. If it does, the process ends; otherwise, adjustments are made.

[0070] Furthermore, the first adjustment scheme is as follows:

[0071] The system detects whether the temperature gradient of the fuel cell stack exceeds the set value. If it does not exceed the set value, no adjustment is needed. If it exceeds the set value, the system calculates the optimal scheme for the redistribution of fan power, position, grille opening size, grille air inlet position, and fuel cell stack output power at different positions based on the magnitude of the temperature gradient, the flow rate and temperature of the cooling gas at the grille inlet, to achieve the temperature uniformity requirement and ensure that the sum of the output power of each fuel cell stack meets the current fuel cell stack output power requirement.

[0072] Furthermore, the second adjustment plan is as follows:

[0073] The system detects whether the upper and lower limits of the fuel cell stack temperature exceed the set values. If the temperature does not exceed the set values, no adjustment is required. If the temperature exceeds the set values, the system calculates the optimal solution based on the magnitude of the abnormal temperature of the fuel cell stack, the flow rate and temperature of the cooling gas at the grid inlet, the fan power, position, grid opening size, grid air inlet position, and the redistribution of the fuel cell stack output power at different positions. This achieves the extreme temperature control requirements, ensuring that the sum of the output power of each fuel cell stack meets the current fuel cell stack output power requirements.

[0074] When the first adjustment scheme and the second adjustment scheme are performed simultaneously, and the difference between the different adjustment parameters in the two adjustment schemes exceeds the corresponding preset range, the priority of the event "controlling the stack temperature to remain within the preset range" is higher than that of the event "controlling the stack temperature gradient to remain within the preset range". When the parameters in the first adjustment scheme and the second adjustment scheme are readjusted to ensure that the adjusted scheme will not increase the stack temperature gradient, the heat dissipation coordinated temperature control processing scheme is executed.

[0075] The central control system controls the fan to move to the corresponding fuel cell stack position or change the direction of the fan to the corresponding fuel cell stack position or perform local purging, adjusts the fan power, grille opening size, and air intake position, controls the air compressor and hydrogen flow control valve, adjusts the air and hydrogen intake, and thus adjusts the output power of fuel cell stacks at different positions.

[0076] If the fuel cell stack temperature does not meet the requirements, the production heat dissipation coordinated control temperature treatment scheme will continue to be implemented until the fuel cell stack temperature requirements are met or the external environment changes so that a new production heat dissipation coordinated control temperature treatment scheme needs to be implemented.

[0077] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention, and applications, modifications and variations thereof will be apparent to those skilled in the art.

[0078] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A distributed HT-PEMFC stack for aircraft with synergic thermal management of heat production, characterized by, The application relates to a high-temperature proton exchange membrane fuel cell (HT-PEMFC) system, which comprises the following components: a plurality of low-power HT-PEMFC stacks; a heat dissipation assembly, which comprises an air inlet grille, an air inlet channel, a heat dissipation fan, an air outlet channel and an air outlet; a sensor assembly, which comprises a temperature sensor and a flow sensor; a central control system, which is used for controlling the HT-PEMFC stack power output size, the air inlet grille opening area size, the grille air inlet channel position, the heat dissipation fan power size and position and the re-distribution of the stack output power at different positions.

2. A distributed HT-PEMFC stack with synergistic thermal management of heat production for aircraft as claimed in claim 1, wherein, The temperature sensor is used for detecting the temperature size and distribution of the stacks at different positions in the cavity and detecting the cooling gas temperature of the air inlet.

3. A distributed HT-PEMFC stack with synergistic thermal management of heat production for aircraft as claimed in claim 2, wherein, The flow sensor is used for detecting the cooling gas flow of the air inlet.

4. A distributed HT-PEMFC stack with synergistic thermal management of heat production for aircraft as claimed in claim 3 wherein, The central control system is used for receiving the temperature signals transmitted by the temperature sensors in the cavity and the air inlet and the cooling gas flow signals transmitted by the air inlet flow sensor.

5. The method of claim 1-4, wherein the method is a method of managing the heat production and dissipation of a distributed HT-PEMFC power plant for an aircraft with synergic heat management of the heat production, characterized in that, The application further relates to a temperature dissipation adjustment method for the HT-PEMFC system. In the initial stage of the aircraft take-off, the maximum opening of the grille is kept, and the heat dissipation fan position and power are adjusted according to the stack temperature distribution gradient and size. In the aircraft flight stage, the temperature dissipation adjustment is carried out through the first adjustment scheme and / or the second adjustment scheme, and the specific adjustment methods are as follows: It is judged whether the first adjustment scheme and the second adjustment scheme exist simultaneously, and when it is judged that the two adjustment schemes do not exist simultaneously, the first adjustment scheme or the second adjustment scheme is executed. When it is judged that the two adjustment schemes exist simultaneously, it is further judged whether the difference of the adjustment parameters of the two adjustment schemes is within the corresponding preset range, and when it is judged that the difference is within the preset range, the second adjustment scheme is carried out; when it is judged that the difference is not within the preset range, the parameters, which do not meet the requirement, in the first adjustment scheme and the second adjustment scheme are adjusted until the difference meets the preset range value. After the above steps, it is further judged whether the stack temperature meets the requirement, and if yes, the adjustment is ended; if not, the adjustment is continuously carried out.

6. A method of heat dissipation and thermal management control of a distributed HT-PEMFC power plant for an aircraft with synergic heat management of heat dissipation, according to claim 5, characterized in that, The first adjustment scheme is as follows: It is detected whether the stack temperature gradient exceeds the set value, and when the set value is not exceeded, the adjustment is not needed; when the set value is exceeded, the optimal scheme of the heat dissipation fan power size, position, grille opening size, grille air inlet channel position and re-distribution of the stack output power at different positions is calculated according to the temperature gradient size, the cooling gas flow and temperature at the grille inlet, the temperature uniformity requirement is realized, and the sum of the stack output powers needs to meet the current time fuel cell stack output power requirement.

7. A distributed HT-PEMFC stack with waste heat co-generation and thermal management for aircraft as claimed in claim 5 wherein, The second adjustment scheme is as follows: It is detected whether the upper and lower limits of the stack temperature exceed the set value, and when the set value is not exceeded, the adjustment is not needed; when the set value is exceeded, the optimal scheme of the heat dissipation fan power size, position, grille opening size, grille air inlet channel position and re-distribution of the stack output power at different positions is calculated according to the abnormal stack temperature size, the cooling gas flow and temperature at the grille inlet, the extreme temperature control requirement is realized, and the sum of the stack output powers needs to meet the current time fuel cell stack output power requirement.

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