As an approach for estimation of the droplet size in the molten salt-liquid metal extraction process, a droplet formation experiment at room temperature was conducted to evaluate the applicability of the Scheele-Meister model with water-mercury system as a surrogate that is similar to the molten salt-liquid metal system. In the experiment, droplets were formed through the nozzle and the droplet size was measured using a digital camera and image analysis software. As nozzles, commercially available needles with inner diameters (ID) of 0.018 cm and 0.025 cm and self-fabricated nozzles with 3-holes (ID: 0.0135 cm), 4-holes (ID: 0.0135 cm), and 2-holes (ID: 0.0148 cm) were used. The mercury penetration lengths in the nozzles were 1.3 cm for the needles and 0.5 cm for the self-fabricated nozzles. The droplets formed from each nozzle maintained stable spherical shape up to 20 cm below the nozzle. The droplet size measurements were within a 10% error range when compared to the Scheele-Meister model estimates. The experimental results show th

In a PEMFC gas channel with a trapezoidal cross-section, the effect of air and water inlet velocities on water removal characteristics is numerically studied via the volume of fluid(VOF) method. When the channel wall contact angle is 60 degrees, the air inlet velocities higher than 2.5 m/s are advantageous to obtain lower GDL surface water coverage ratio(WCR). The WCR increases as the wall contact angle increases to 90 or 120 degrees due to the relatively lower surface tension force. In overall, WCR decreases as the air inlet velocity increases and WCR increases as the water inlet velocity increases.

The effect of PEMFC trapezoidal channel wall contact angle on water removal characteristics is investigated with the volume of fluid (VOF) method. Two different contact angles 60 and 90 degrees are selected. In the case of the side and top wall contact angle of 60 degrees, stable semi-spherical droplets move along the top wall slowly. In contrast, complex shaped droplets move along the lower edge in the case of 90 degrees. Moreover, it is shown that very complex interaction patterns between different droplets which introduced into the channel at different times.

The lattice Boltzmann method (LBM) is applied to study the behavior of liquid droplet inside a PEMFC gas channel. To validate the fluid-fluid interaction model, the relationship between the pressure jump across the interface and the bubble radius is investigated for a static bubble to confirm the Laplace’s law. To evaluate the fluid-solid interaction model, static contact angle is calculated by changing the interaction parameter. Also, a constant gravitational force is applied to study the temporal evolution of liquid droplet placed on the bottom wall in a three dimensional periodic channel.

Numerical simulations of liquid water droplets interacting with gas channel walls in a polymer electrolyte membrane fuel cell are performed with the volume of fluid (VOF) method. To investigate the effect of channel wall wettability, the contact angles of gas diffusion layer (GDL) and the side/top walls are varied as 45, 90, and 140 degrees. Two different water injection inlet locations are selected to investigate the interactions of liquid water with the different gas channel walls. As the GDL contact angle increases, the GDL surface water coverage ratio and the water volume ratio decrease. When the water injection hole is located near the side wall, the GDL surface water coverage ratio decreases and the water volume ratio increases as the contact angle of the side and top walls decreases. In conclusion, the GDL surface water coverage ratio and the water volume ratio may compete with each other to determine the fuel cell performance.

The dynamic interaction of liquid droplets emerging from the gas diffusion layer surface is modeled to study the behavior of liquid water inside the gas channel of a polymer electrolyte membrane fuel cell with the volume of fluid (VOF) formulation. The surface contact angle of gas diffusion layer is varied as 45, 90, and 140 degrees. The air inlet velocity in the gas channel is varied as 5, 10, and 15 m/s. The water inlet velocity from micro pores is varied as 0.5, 1, and 2 m/s. As the contact angle increases, water coverage ratio increases. As the air inlet velocity and the water inlet velocity increase, water droplets move faster toward the channel exit as evidenced from the water front location plots. In summary, the hydrophobic wall contact angle and higher air/water inlet velocities provide better water removal characteristics.