Principle analysis of hydrogen fuel cell new energy vehicle

Fuel cell is an energy conversion device, which can convert the electrochemical energy of fuel into electrical energy. Because it is an electrochemical generator, it is called a fuel cell. A fuel cell that uses hydrogen as fuel is a hydrogen fuel cell. Hydrogen fuel cell can be understood as the reaction of water electrolysis into hydrogen and oxygen. The reaction process of hydrogen fuel cell is clean and efficient. Hydrogen fuel cells are not limited by the thermal efficiency of Carnot cycle. The thermal efficiency of traditional automobile engines is about 42%, and the efficiency can reach more than 60%.

Different from rockets, hydrogen fuel cells generate kinetic energy through the violent reaction of hydrogen and oxygen combustion, and release Gibbs free energy in hydrogen through catalytic devices. Gibbs free energy is electrochemical energy involving entropy and Fourier theory. The working principle of hydrogen fuel cell is that hydrogen is decomposed into hydrogen ions (protons) and electrons through the catalyst (platinum) at the anode of the cell. Among them, hydrogen ions pass through the proton exchange membrane to reach the cathode, and oxygen reacts into water and heat, and the corresponding electrons flow from the anode to the cathode through the external circuit to generate electric energy.

Now proton exchange membrane fuel cell technology is mainly used in hydrogen fuel cell vehicles. The system composition of hydrogen fuel cell vehicles usually covers fuel cell stacks and hydrogen storage tanks, as well as automotive power cells and fuel cell DC boost converters, power control units and power motors. At present, the power density of advanced fuel cell stack is 3.0kW/L, which needs to be used with DC boost converter and automobile power battery. Then the voltage can adapt to the high voltage of 650 volts to drive the automobile power motor. At the same time, similar to the battery management system BMS of automobile power battery, the fuel cell also needs an accurate monitoring and management system FCMS to quickly adjust the parameters related to the reaction through the discharge state. To store hydrogen, a 70Mpa high-pressure liquid hydrogen storage tank is usually used.