Due to the paramagnetic property of liquid oxygen,the Kelvin force can be induced in liquid oxygen under non-uniform magnetic field.Based on the volume of fluid(VOF)model,the positioning effect of the force in liquid ...Due to the paramagnetic property of liquid oxygen,the Kelvin force can be induced in liquid oxygen under non-uniform magnetic field.Based on the volume of fluid(VOF)model,the positioning effect of the force in liquid oxygen tanks is analyzed under various Bond numbers(Bo)and magnetic Bond numbers(Bom).The results show that the magnetic field has the effect of repositioning the liquid oxygen in the tank when the gravity field is not enough or absent.Additionally,the gas-liquid interface has a periodic fluctuation during the process due to the inhomogeneous Kelvin force distribution,and more effective suppression of fluctuation can be achieved under the condition of a larger Bom.The new method of controlling gas-liquid interface of liquid oxygen tank under micro gravity condition is hoped to be developed in the future.展开更多
Previous work （Hussain et al. （2013）. Chemical Engineering Science, 101, 35） has pointed out that the conventional, one-dimensional population balance equation for aggregation can be expanded to accurately reprodu...Previous work （Hussain et al. （2013）. Chemical Engineering Science, 101, 35） has pointed out that the conventional, one-dimensional population balance equation for aggregation can be expanded to accurately reproduce the results of discrete simulations of spray fluidized bed agglomeration. However, some parameters had to be imported from the discrete simulation （Monte-Carlo）. The present paper shows how the expanded population balance can be run without importing parameters from the Monte-Carlo simulation. The expanded population balance still reproduces the results of Monte-Carlo simulations accurately, taking into account key micro-scale phenomena （sessile droplet drying, efficiency of collisions）, but with much lower computational cost. Required input parameters are just the drying time of sessile droplets （calculated in advance）, and the prefactor of an equation that correlates particle collision frequency with fluidized bed expansion. In this way, the expanded population balance is, apart from autonomous, also （nearly） predictive. Its performance is demonstrated by comparisons with both Monte-Carlo results and experimental data for various operating conditions （binder mass flow rate, gas temperature）. Despite formally being a one-dimensional expression, the expanded population balance captures additional properties, such as the number of wet particles and the number of droplets in the system, which are even difficult to measure in exoeriments.展开更多
基金supported by the Natural Science Foundation of China(No.51706190)the State Scholarship Fund of China Scholarship Council。
文摘Due to the paramagnetic property of liquid oxygen,the Kelvin force can be induced in liquid oxygen under non-uniform magnetic field.Based on the volume of fluid(VOF)model,the positioning effect of the force in liquid oxygen tanks is analyzed under various Bond numbers(Bo)and magnetic Bond numbers(Bom).The results show that the magnetic field has the effect of repositioning the liquid oxygen in the tank when the gravity field is not enough or absent.Additionally,the gas-liquid interface has a periodic fluctuation during the process due to the inhomogeneous Kelvin force distribution,and more effective suppression of fluctuation can be achieved under the condition of a larger Bom.The new method of controlling gas-liquid interface of liquid oxygen tank under micro gravity condition is hoped to be developed in the future.
基金financial support provided by the German Science Foundation(DFG) within the framework of graduate school GRK-1554by the Alexander von Humboldt Foundation(research fellowship for Jitendra Kumar)
文摘Previous work （Hussain et al. （2013）. Chemical Engineering Science, 101, 35） has pointed out that the conventional, one-dimensional population balance equation for aggregation can be expanded to accurately reproduce the results of discrete simulations of spray fluidized bed agglomeration. However, some parameters had to be imported from the discrete simulation （Monte-Carlo）. The present paper shows how the expanded population balance can be run without importing parameters from the Monte-Carlo simulation. The expanded population balance still reproduces the results of Monte-Carlo simulations accurately, taking into account key micro-scale phenomena （sessile droplet drying, efficiency of collisions）, but with much lower computational cost. Required input parameters are just the drying time of sessile droplets （calculated in advance）, and the prefactor of an equation that correlates particle collision frequency with fluidized bed expansion. In this way, the expanded population balance is, apart from autonomous, also （nearly） predictive. Its performance is demonstrated by comparisons with both Monte-Carlo results and experimental data for various operating conditions （binder mass flow rate, gas temperature）. Despite formally being a one-dimensional expression, the expanded population balance captures additional properties, such as the number of wet particles and the number of droplets in the system, which are even difficult to measure in exoeriments.
