Fuel cell cold start system based on magnetothermal effect and control method

Abstract

The invention relates to a fuel cell cold start system based on magnetothermal effect and a control method, the fuel cell cold start 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 a cooling loop of the fuel cell thermal management unit is communicated with the fuel cell stack, a plurality of magnetic mass heat reservoirs and pulse magnets are located in the cooling loop, one magnetic mass heat reservoir is arranged between every two pulse magnets, the pulse magnets are electrically connected with a pulse power supply, and a circulating loop of magnetization heat release, demagnetization heat absorption and magnetization heat release is constructed in a low-temperature environment by utilizing the magnetocaloric effect of magnetic materials. The heat in the environment is continuously transferred to the fuel cell stack to realize the cold start of the fuel cell, the loss of irreversible electrochemical active area caused by interface separation due to ice melting is avoided, the energy consumption is low, the utilization rate of the fuel cell can be improved, and the endurance mileage of the fuel cell can be prolonged.

Description

technical field [0001] The invention belongs to the technical field of fuel cells, and relates to a fuel cell cold start system and a control method based on the magnetocaloric effect. 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 cold start 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 cold-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 release of oxygen. The transmission is blocked, and the voltage drops suddenly; wh...

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Problems solved by technology

[0003] When the fuel cell is cold-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, causing the active sites of the catalytic layer to be covered and oxygen The transmission is blocked, and the voltage drops suddenly; when the catalytic layer is completely covered by ice and the temperature of the stack 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] The current technical solution for the cold start of the fuel cell is 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. 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 irreversible electrochemical reactions. loss of active area

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