Fuel cell cold start system based on liquid magnetic heat flow and control method

Abstract

The invention relates to a fuel cell cold start system based on liquid magnetic heat flow and a control method, a fuel cell thermal management unit is communicated with a fuel cell stack, and a cooling loop and a magnetic working medium loop are arranged in the fuel cell thermal management unit, a heat management controller is electrically connected with a first circulating pump, a first radiator, a three-way electromagnetic valve, a first temperature sensor and a second temperature sensor in the cooling loop, and is electrically connected with a second circulating pump, a second radiator and a third temperature sensor in the magnetic working medium loop; the cold start of the fuel cell is realized by circularly transferring heat in the environment to the fuel cell stack by constructing magnetization heat release-demagnetization heat absorption-magnetization heat release in a low-temperature environment by utilizing a magnetothermal effect of a magnetic material, so that the energy consumption is low, the utilization rate and the endurance mileage of the fuel cell are favorably improved, and the loss of irreversible electrochemical active area caused by interface separation of platinum and ion resin due to ice melting is avoided.

Description

technical field [0001] The invention belongs to the technical field of fuel cells, and relates to a fuel cell cold start system and control method based on liquid magnetic heat flow. 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 does not take any protective measures, when it is started in a low temperature environment below 0°C, 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...

AI Technical Summary

Problems solved by technology

[0003] When the fuel cell does not take any protective measures, when it is started in a low temperature environment below 0°C, 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 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] 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. The water generated by the electric stack will freeze, and firstly, ice will be generated at the part where the surface of the platinum particles is in contact with the ion resin. Once the temperature rises to room temperature, the melting of the ice at the interface between the platinum and the ion resin will cause the interface to detach, resulting in an irreversible electric current. loss of chemically active area

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