The flow field is a pivotal part to manage the transport of water and gas in proton exchange membrane fuel cell. However, the reported water measurement methods (e.g., X-ray and electrochemical impedance spectroscopy (EIS)) cannot give a comprehensive understanding water distribution in the flow field, resulting in challenges in optimizing the channel design and enhancing fuel cell performance. Therefore, we propose a water measurement method combining the X-ray radiography with EIS to investigate the effect of different operating conditions on the growth law and distribution of liquid water in parallel and serpentine flow fields. The attenuation coefficient of liquid water to X-ray is calibrated with constant tube-current and tube-voltage of X-ray generator. Besides, the parallel flow field with hydrophobic treatment is studied. The results show that the water accumulation of the parallel flow field is far more than the serpentine flow field, and the water content of the middle region is higher than that of other regions in the parallel flow field. Furthermore, operating conditions (cathode inlet gas flow rate, inlet gas humidity, and back pressure) have little effect on the liquid water content of the middle region in the parallel flow field. The polarization curve, EIS result, and X-ray radiography show that the performance and water drainage capacity of the hydrophobic parallel flow field are better than the normal one.
Phosphogypsum (PG) is a solid waste produced in the wet process of producing phosphoric acid.Lignite is a kind of promising chemical raw material.However,the high sulfur of lignite limits the utilization of lig-nite as a resource.Based on fluidized bed experiments,the optimal reaction conditions for the production syngas by lignite chemical looping gasification (CLG) with PG as oxygen carrier were studied.The study found that the optimal reaction temperature should not exceed 1123 K;the mole ratio of water vapor to lignite should be about 0.2;the mole ratio of PG oxygen carrier to lignite should be about 0.6.Meanwhile,commercial software Comsol was used to establish a fuel reaction kinetics model.Through computational fluid dynamics (CFD) numerical simulation,the process of reaction in fluidized bed were well captured.The model was based on a two-fluid model and coupled mass transfer,heat transfer and chemical reac-tions.This study showed that the fluidized bed presents a flow structure in which gas and solid coexist.There was a high temperature zone in the middle and lower parts of the fluidized bed.It could be seen from the results of the flow field simulated that the fluidized bed was beneficial to the progress of the gasification reaction. 相似文献
Solid polymer electrolyte with good thermal stability and flexibility is an excellent candidate for solid-state lithium metal batteries, while its low ionic conductivity caused by high crystallinity limits its application at ambient temperature. Here a metal organic framework (zeolitic imidazolate framework-8, ZIF-8) composited comb-like methoxy poly(ethylene glycol) acrylate polymer electrolyte (MCPE) with high ionic conductivity (9.96 × 10−5 S cm−1 at 30 °C) is prepared by an in situ UV polymerization method. The as-prepared MCPE exhibits improved mechanical property due to the introduction of porous ZIF-8 nanofillers, which is beneficial to suppress the growth of lithium dendrites. Consequently, the LiFePO4||MCPE||Li cells show a high capacity of 116 mAh g−1 at 30 °C and 0.5 C, and maintain 89.4% of initial capacity after 150 cycles with the average Coulombic efficiency of 99.9%. These results demonstrate that the MCPE shows great potential in solid-state lithium metal batteries near room temperature. 相似文献
Journal of Inorganic and Organometallic Polymers and Materials - The original version of this article unfortunately contained mistakes. In line 9 of the abstract, 5% should read as 2%. The... 相似文献