| Under the goal of "double carbon",clean energy with hydrogen as the core can accelerate the rapid transformation of traditional energy system.Hydrogen energy has the advantages of wide source,clean and efficient,and rich application scenarios.Coupling with electric energy in transportation,industry,architecture and many other fields will be an important choice to achieve the goal of "double carbon".Proton Exchange Membrane Fuel Cell(PEMFC)has the advantages of low operating temperature and fast startup time,and has broad prospects in the development of hydrogen energy applications.There are still many technical problems in the storage and transportation of hydrogen used by PEMFC,and ammonia as a hydrogen carrier can effectively solve the technical problems of hydrogen storage and transportation.Some ammonia will remain in hydrogen when ammonia is decomposed to produce hydrogen.The optimization design of ammonia containing hydrogen PEMFC and the design of power supply system are of great significance to the improvement of ammonia resistance of PEMFC and the household use of fuel cells.This research focuses on the household use of hydrogen fuel cells,aiming at the problem of residual ammonia in hydrogen production from ammonia decomposition.Firstly,a PEMFC single cell model of a household ammonia-containing hydrogen fuel cell was built to study the effect of different contents of ammonia in hydrogen on the output performance of PEMFC,and then the improvement effect of the output performance of the hydrogen fuel cell containing ammonia by the thickness of the catalytic layer,the porosity of the gas diffusion layer and the working temperature of the cell was studied.Finally,an equivalent ammonia-hydrogen fuel cell stack with a rated output power of 6 k W is used to build a household ammonia-containing hydrogen fuel cell power supply system,the system includes a front-stage DC/DC converter and a rearstage inverter.The main findings are as follows:Ammonia reduces the concentration of hydrogen involved in the anode reaction by occupying the active sites of hydrogen on the surface of the catalytic layer,which eventually leads to a decrease in the performance of the PEMFC.Compared with pure hydrogen as the anode fuel gas,the maximum power density of the PEMFC is reduced by 69.5% when the ammonia content is 100 ppm.An appropriate increase in the thickness of the catalytic layer can improve the performance of the ammonia-containing hydrogen fuel cell.When the ammonia content is 10 ppm,the optimal thickness of the catalytic layer is 200 μm.The increase of the porosity of the gas diffusion layer can accelerate the diffusion of substances and improve the battery performance.When the ammonia content is 10 ppm,the optimal gas diffusion layer porosity range is 0.5-0.7.The increase of the battery operating temperature can not only accelerate the diffusion of substances,but also accelerate the internal reaction rate of the battery.When the ammonia content is 10 ppm,the optimal battery operating temperature range is 70 ℃-90 ℃.The boost circuit using double closed-loop PI control can rapidly increase the voltage output of the ammonia-containing hydrogen fuel cell stack with a rated output power of 6 k W to 380 V.When the load and the input side voltage are disturbed,the output voltage can be restored after a brief fluctuation return to 380 V.The voltage-type full-bridge inverter circuit using unipolar sinusoidal pulse width modulation can stably output 380 V direct current to an effective value of 220 V alternating current,and when the load is disturbed,it can also quickly stabilize to an effective value of 220 V;the frontstage DC/DC converter and the rear-stage inverter are integrated into a household ammonia-containing hydrogen fuel cell power supply system.After the fuel cell start-up stage,the RMS value of the output voltage on the alternating current side of the system can also reach 220 V,and the total harmonic distortion is 2.23%,meeting the requirement of less than 5% of the grid. |
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