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Summary: The object of this study is the manufacturing processes and fluorinated ethylene propylene (FEP) contents on the cell performance of the proton exchange membrane fuel cell (PEMFC). These results are useful for optimizing gas diffusion layer (GDL) fabrication processes and the operating conditions of the PEMFC. A traditional GDL with a micro porous layer (MPL) can enhance the water management ability. For the case of the one‐stage GDL manufacturing process, carbon paper with an FEP content of 10 wt% has the best fuel cell performance and limiting current density. Besides, in the two‐stage GDL fabrication process, when the cathode fuel is air, carbon paper with the same 10 wt% FEP content can delay the occurrence of limiting current density. The types of carbon black have remarkable influences on water management capabilities. It is noted that the XC‐72R carbon powder has a relatively appropriate pore volume to have enough water to keep the membrane moist and avoid water flooding. The higher the gas humidification temperature, the faster the electrochemical reaction rate. But when the operating current density is high, it will generate too much water, resulting in water flooding and a decrease in the PEMFC performance. Therefore, when the cathode fuel is air and the inlet humidification temperature is 80°C for the anode and 50°C for the cathode, the limiting current density can be effectively extended to maintain the cell performance. [ABSTRACT FROM AUTHOR]

Summary: Utilization of fuel cells as a source of driving power would expose them to dynamic variable loading conditions depending on the driving profile and environmental circumstances. The present research study aims to investigate the dynamic behavior of a single‐cell proton exchange membrane fuel cell (PEMFC) subjected to various loading modes and operation parameters. A fuel cell with hydrogen gas as fuel has been assembled as the test module. Three different voltage load modes were designed and applied to the cell. The corresponding current variation of the cell as its dynamic response was measured. The dynamic behavior of the cell was examined for various control parameters such as the cell working temperature, inlet humidification temperature, and stoichiometry. The experimental results indicated that the working temperature of 65°C provided the best fuel‐cell performance among the three investigated working temperatures of 45°C, 55°C, and 65°C. At different humidification temperatures, the Ta/Tc = 70°C/60°C humidification condition led to the best fuel cell performance due to the adequate wettability of the membrane. However, the humidification temperature might also have induced a minimal impact on the dynamic response of the fuel cell. Although past studies have indicated that higher stoichiometry achieved better cell performance, the experimental data of this study demonstrated that the cell performance of λa/λc = 1.5/2.0 was better than λa/λc = 1.0/1.0 or 3.0/3.0. The influence of the load modes on the performance of the fuel cell was distinguished when the load was high and driving load changed rapidly. Thus, in the present study, the dynamic behavior of a single cell has been investigated and the outcomes can be directly employed for validation of future theoretical models. [ABSTRACT FROM AUTHOR]

Summary: A numerical study is performed to investigate the influence of geometrical factors on the performance characteristics of a laminar thermally developing flow of phase change nano‐suspensions in a rectangular minichannel considering axial wall conduction effects. The phase change material dispersed in the pure water is considered N‐eicosane with the onset point of melting of 34.7°C, latent heat of fusion of 243 J/g, and particle size of 200 nm. The volume fractions of the phase change nano‐suspensions are 2% and 10%, and the Reynolds number is in the range of 200 to 1500. To evaluate the influences of geometrical parameters on the cooling performance of the minichannel heat sinks, five minichannels are investigated, with aspect ratios (ration between channel height and width) ARch of 1, 1.25, and 1.5 and bottom wall thicknesses Hbw of 0.5, 1, and 1.5. The results reveal that the axial wall conduction significantly affects the heat transfer process of a flow in a minichannel at a low Reynolds number, and this effect is more remarkable with a shallower channel and a thicker bottom wall. Five performance indicators are used to systematically evaluate the heat transfer characteristics of the minichannels, including dimensionless heat flux at the bottom wall, temperature suppression, heat transfer effective ratio, heat dissipation of the extended wall, and figure of merit. [ABSTRACT FROM AUTHOR]