The focus of this paper is on the effect of velocity and radius distribution on jet breakup. A theoretical model is established to analyze and predict the velocity distribution along the jet, which is physically and mathematically continuous. The simplified forms of the breakup time, the disturbance growth rate, and the disturbance level considering the velocity and radius distribution are presented. A series of prediction methods for predicting the jet breakup length and droplet size are developed. A Newtonian laminar jet falling vertically was experimentally observed to validate the theoretical model and prediction methods. It is shown that the relaxation of the velocity profile leads to the rapid contraction of the jet radius near the outlet, which leads to the increase in the growth rate of the instability disturbance. The surface tension prevents the growth rate of disturbance from increasing by restraining the contraction of jet radius. The final amplification of jet velocity and contraction due to gravity acceleration depend on the Froude number and breakup length. When the influence of jet radius distribution on the growth rate of disturbance is considered, the breakup time is indirectly affected by the breakup length. The experimental and predicted results show that the accelerated falling of jet lengthens the breakup length traveled by the jet in a shortened breakup time due to the contraction of jet radius. The droplet volume is proportional to the predicted jet cross-sectional area at the breakup position and the Rayleigh wavelength determined by the nozzle radius.

The study conducted isothermal tests for biochar-based N-absorption reaction in Chemical Looping Ammonia Generation to investigate the factors affecting biochar conversion, the kinetic model, and the reaction mechanism. The results show that the N₂ gas flows had little effect on biochar conversion. Raising the reaction temperature and the molar ratio of α-Al₂O₃ to C enhanced the conversion of biochar. When the N₂ flow rate was set to 200 mL/min, the reaction temperature to 1600 °C, and the α-Al₂O₃/C molar ratio to 3:3, the biochar conversion reached its peak at 95.45%. After evaluating several kinetic models, the D₁ diffusion model was found to provide the closest match to the biochar conversion. The activation energy decreased from 241.91 kJ/mol at a 1:3 α-Al₂O₃/C molar ratio to 146.77 kJ/mol at a 3:3 ratio with an increasing α-Al₂O₃/C molar ratio. The biochar’s high specific surface area and abundant pore structure facilitated a rapid reaction between carbon and oxygen on the carbon surface. Additionally, the diffusion of oxygen produced during the decomposition of α-Al₂O₃ became the limiting factor in the N-absorption reaction.