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Adequate water management is critical in proton exchange membrane fuel cells for improving performance and durability. In this paper, we present results of experiments allowing to quantify the effect of a temperature difference between anode and cathode flow field plates on the transport of water. The results confirm the existence of a temperature‐gradient driven flux between the anode and cathode compartments. They show the strong interplay between water management and heat management and they confirm that water flows mostly in vapor form through the porous media of the MEA. Apart from the current density and the difference between the temperature of the electrodes and of the flow field plates, the water flux in the direction perpendicular to the membrane is also (weakly) dependent on the humidification of the gases. No significant effect has been measured as a function of the GDL thickness as well as of the presence or absence of a MPL. However, using a MPL improves significantly the performance of the fuel cell.

The objective of this work was to investigate experimentally water and heat transfers in a proton exchange membrane fuel cell. The experiment consisted in measuring, at the anode and at the cathode, the average temperature of the electrodes using small platinum wires, heat fluxes using heat flux sensors and water fluxes by means of water balance. Three thermal configurations related to the temperature imposed to the plates were studied. The measurements put forward a strong influence of the temperature profile on the water transport. On the whole, water fluxes were oriented in the same direction as the heat fluxes which depend on the temperature difference between the MEA and the plates. The results allowed confirming -at least for the materials and the operating conditions used in this work -that water produced by the electrochemical reaction crossed the diffusion layers in vapor phase. In addition, the effective thermal conductivity of porous layers, a key parameter for the analysis of heat transfer in the fuel cell, was estimated in situ.Water management in proton exchange membrane fuel cell is a fundamental issue and is widely studied, but its interplay with heat transfer is quite often left out. However, recent works have examined the impact of the temperature field on water transport in fuel cells. In 2002, Djilali and Lu 1 focused on the modeling of non-isothermal and non-isobaric effects. They found a typical mean temperature difference of 1 to 5 • C between the bipolar plate and the cathode, as a function of the current density and thermo-physical properties of materials. showed, by considering a non-isothermal operating fuel cell, that evaporation/condensation (heat pipe effect) through the porous layer may have a significant effect at high current densities. Eikerling 4 also showed that at a current density of 1 A cm −2 , the evaporation rate at the electrode is sufficient to remove all water produced at the cathode in vapor phase. To visualize this phenomenon, Hickner et al., 5,6 Kim and Mench 7 and Fu et al. 8 used neutron radiography and highlighted the importance of evaporation at high current densities. The temperature influence on water is significant, on its state but also on its transport: the works of Kim and Mench, 7 Fu et al. 8 or Hatzell et al. 9 showed that water goes preferentially toward the colder side of the fuel cell.Because of the physical complexity and of the technical difficulties associated with experiments giving access to local data, modeling remains commonly used but it is important to perform accurate measurements of temperature in all parts of the cell. In 2004, Vie and Kjelstrup 10 were the first to measure the local temperature near the electrodes using thermocouples (120 μm in diameter). By measuring the temperature at the membrane/electrode and channel/GDL interfaces, they estimated the thermal conductivity of the membrane and of the electrode-GDL assembly. Zhang et al. 11,12 used thermocouples with a diameter of 100 μm placed at the GDL/electrode interface to measure t...

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Electrochemical noise analysis (ENA) is performed on ICR 18650 commercial lithium-ion batteries. The interest of ENA relates with the possibility of in-situ diagnostics during charging or discharging of the battery. Thus, the extraction of small voltage fluctuations should take into account the time evolution of the mean signal. The non-stationary character of the phenomenon (charging and discharging battery) limits the use of traditional methods of signal filtering and attenuation, so a special methodology has been developed to calculate the noise standard deviation (STD). A good reproducibility of the results has been demonstrated, and V-shape form curves have been obtained with a minimum STD value at about 55 % of state of charge (SOC). It can be noted also that fast discharge provided with 3.3 Ω load is noisier than the slow one with 5 Ω load. Some promising results have been obtained regarding the possibility of battery state of health determination.