Fuel cell thermal management system based on magnetic heat and control method

Abstract

The invention relates to a fuel cell thermal management system based on magnetic heat and a control method, the fuel cell thermal management system comprises a fuel cell stack, a fuel cell thermal management unit and a thermal management controller, the thermal management controller is electrically connected with the fuel cell thermal management unit, and the fuel cell thermal management unit is communicated with the fuel cell stack. A permanent magnet and a magnetic mass heat reservoir are connected in series in a circulation loop of the fuel cell heat management unit, a stepping motor drives the magnetic mass heat reservoir to enter and exit a magnetic field cavity of the permanent magnet, magnetization heat release and demagnetization heat absorption are constructed, a fuel cell stack is started at low temperature through heat transfer, the energy consumption is low, irreversible electrochemical active area loss caused by interface separation due to stack icing is avoided, extra energy consumption is avoided, and the utilization rate of the fuel cell is improved.

Description

technical field [0001] The invention belongs to the technical field of fuel cells, and relates to a fuel cell thermal management system and a control method based on magneto-caloric. Background technique [0002] As one of the solutions for vehicle electrification, the large-scale commercialization of fuel cell vehicles still has problems such as high cost, short life, and weak hydrogen infrastructure. Among them, the low-temperature start-up problem of fuel cells is one of the key technical bottlenecks hindering the commercialization of fuel cells, and it is the biggest challenge for fuel cell vehicles to operate in winter. [0003] When the fuel cell is started in a low temperature environment below 0°C without taking any protective measures, the water produced by the reaction will first freeze inside the catalytic layer, resulting in the covering of the active sites of the catalytic layer and the transmission of oxygen. When the catalytic layer is completely covered by i...

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Problems solved by technology

[0003] When the fuel cell is started in a low temperature environment below 0°C without taking any protective measures, the water produced by the reaction will first freeze inside the catalytic layer, resulting in the covering of the active sites of the catalytic layer and the transmission of oxygen. Blocked, the voltage drops suddenly; when the catalytic layer is completely covered by ice and the stack temperature has not risen above 0°C, ice will form in the diffusion layer and flow channel, resulting in cold start failure

On the other hand, the freezing process of the catalytic layer can lead to gaps between the catalytic layer and the proton exchange membrane, while the freezing / thawing cycle can cause the collapse and densification of the microporous structure of the catalytic layer and the coarsening of platinum particles in the catalytic layer. , resulting in the reduction of the electrochemically active surface area and it is difficult to recover, thereby causing permanent damage to the power generation performance of the fuel cell, and the more cycles, the lower the cold start temperature, the greater the damage to the battery

[0004] At present, the technical solution for low-temperature start-up of the fuel cell is mainly to use gas purging to reduce the water content of the fuel cell membrane electrode when the stack is shut down, thereby reducing the formation of solid ice, but only when the stack temperature does not rise above 0°C When the stack produces water, it will freeze, and first of all, ice will be generated on the surface of the platinum particles in contact with the ion resin. Once the temperature rises to room temperature, the ice at the interface between the platinum and the ion resin will melt and cause the interface to detach, resulting in an irreversible electrochemical reaction. loss of active area

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