The
gas diffusion layer (GDL) plays a key role in water management.
The effects of the structure, wettability, and rib-channel width ratio
on liquid water transport in GDL are studied using a multiphase lattice
Boltzmann method (LBM) model. It is found that the liquid water in
GDL shows capillary fingering behavior. With the increase of carbon
fiber diameter or porosity, the water saturation in GDL increases,
and the time for liquid water to break through GDL decreases. The
porosity has a significant effect on the water saturation in GDL.
The water saturation of GDL with a contact angle of 140° is less
than that of GDL with a contact angle of 80°. The water saturation
in GDL decreases as the rib-channel width ratio increases, while the
rib-channel width ratio has little effect on the water saturation
in the region of GDL away from the rib. Compared to the rib with a
contact angle of 140°, the rib with a contact angle of 60°
slightly reduced the water saturation in GDL, and the wettability
of the rib has only a small effect on the water saturation in the
region of GDL near the rib.
There are two problems to be solved in the numerical simulation of the top blown oxygen vacuum refining process. (1) The two-equation turbulence models underpredict the turbulence mixing shear process for high-temperature gradient jet flows. (2) The high compressibility of the jet in a low vacuum environment. In this study, the SST k-ω turbulence model is modified by the composite function of the compressibility factor and the total temperature gradient. Based on the experimental model of the Kotani vacuum jet, the modified turbulence model was used to simulate the supersonic jet behavior of oxygen lance at different ambient temperatures. The reliability of the model is verified by the semi-empirical formula of Ito and Muchi. The simulation results show that the entrainment rate is an important inducing factor. The potential core length and the supersonic core length at the temperature of 1800 K are 2.5 times and 2.0 times that at the temperature of 285 K, respectively. Besides, based on the ejection model established by Ricou and Spalding, the calculation formula of turbulence entrainment rate at different ambient temperatures is obtained. This research work will benefit greatly to the supersonic jet behavior in Vacuum Refining.
A computation fluid-coupled discrete phase model (CFD-DPM) was used to predict the motion characteristics of gas, particle, and liquid phases in the hot metal ladle. The influence of different voltage loading modes, voltage values, and powder injection speeds on the particle motion trail was investigated, while the effects on the particle concentration maximum difference in the stagnation region were discussed. The optimal injection and voltage parameters were proposed. The results are shown as follows: the loading voltage before injection is beneficial to the diffusion of particles in the molten pool. With the increase of voltage and injection speed, the distribution of particles in the upper part of the molten iron tends to be uniform. The bottom of the ladle is the stagnation region. Optimum voltage and injection speed were determined. Under the optimum conditions, particles are evenly dispersed and the particle concentration difference in the stagnation region is small. This research work will benefit greatly to the hot metal ladle desulfurization technology.
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