Abstract:

In order to explore mechanism of concentration and type of inorganic salts on polarization and deformation of water droplet during electric dehydration, water droplets of various salt concentrations and types were studied microscopically in pulsed electric field of both high frequency and high voltage. Water droplets of all tested sodium chloride (NaCl) concentrations showed a trend that the deformation degree increased first but decreased later when the electric frequency and duty ratio were increased. The deformation degree of water droplet increased with increase of NaCl concentration, as a result of increased electric conductivity and ion collision. The electric force on multivalent ions, which is several times stronger than that on monovalent ions, enhanced velocity and momentum of their collision, so the deformation degree of water droplet increased upon increase of ionic valence. Furthermore, the ion activity and hydrolysis affected the deformation degree. In the same high-voltage pulsed electric field, the deformation degree of sodium-containing water droplets changed in the order from high to low as Na₃PO₄> Na₂CO₃> Na₂SO₄> NaCl> NaNO₃ whereas that of chlorine-containing water droplets changed in the order as MgCl₂> CaCl₂> KCl> NaCl> NH₄ClCl. The experimental findings shall facilitate investigating mechanism of electrostaticde-emulsification at high voltage and high frequency.

Key words: high frequency impulse, inorganic salt, polarization, deformation

摘要：

为了深入探究无机盐对电脱水过程水滴极化的影响机理，分别改变无机盐浓度及种类，对高频高压脉冲电场作用下水滴的极化变形进行显微实验研究。结果表明，不同NaCl浓度条件下水滴的变形度随电场频率和占空比的增加呈先增大后降低，由于电导率增大、离子冲击效应等的影响，随着NaCl浓度的增大，水滴的变形度随之增大。高价无机盐离子所受的电场力是一价离子的数倍，有利于其冲击速度和冲击动量的提升，水滴变形度随离子价位升高而增大。另外，由于离子活泼程度以及水解等原因，在同一高压脉冲电场中，不同钠盐溶液水滴变形度顺序为：磷酸钠 >碳酸钠 >硫酸钠 >氯化钠 >硝酸钠。不同氯盐溶液水滴变形度顺序为：氯化镁 >氯化钙 >氯化钾 >氯化钠 >氯化铵。研究成果为高压高频脉冲静电破乳机理的深入探讨奠定了基础。

关键词: 高频脉冲, 无机盐, 极化, 变形