重力场对管内液液间传质影响的数值模拟

Numerical simulation of the effects of gravitational field on mass transfer between two liquids in pipeline

针对管内液液传质现象,建立速度场、重力场及湍流涡旋影响下的质量传递非稳态数学模型。利用PHOE-NICS 3.6软件数值求解,分析了在不同工况下管内柴油与汽油顺序输送界面处的体积分数分布情况。结果表明,在紊流输送下,密度差影响体积分数分布曲线的位置,管道倾角影响体积分数曲线的斜率,重力场对管内液液间传质总体影响较小;在停输下,较重液体处在势能高处时,则产生自然对流,对传质影响很大,且随时间延长持续下去;对较重液体处在势能较低处时,随时间延长,自然对流传质被抑制,二液体分子扩散起主导作用,且产生明显的分层。因此,依据此研究方法所得结果比试验测定提供了更为丰富的体积分数场分布信息。

Aiming at phenomenon of mass transfer between two liquids in pipeline, unsteady mass transfer numerical calculation model was set up, with velocity field, gravitational field and eddy diffusion being considered. Concentration distribution on the interface between diesel fuel and gasoline oil in hatching transportation was simulated based on PHOENICS3. 6 software. The results show that in turbulence transportation, the density variation changes the position of the concentration distributing curve, and pipeline inclination angle affects the slope of the concentration distributing curve. On the whole, the effect of gravitational field on mass transfer between two liquids in pipeline is less. In shutdown pipeline, when the heavier liquid is in the higher energy of position, it leads to natural convection, and has a great influence on mass transfer, which continues with time lasting; but when the heavier liquid is in the lower energy of position, the influence on mass transfer by gravitational field is inhibited with time lasting, and molecular diffusion between two liquids dominates, which results in visible laminations. Therefore, the results based on this research method offer more abundant information about concentration field than those based on experiments.