固相颗粒粒径对浆体流变特性影响的实验研究

Experimental Study on the Influence of Solid Particle Sizeon the Rheological Properties of Slurry

为研究固相颗粒粒径大小对冰浆类固液两相流流变特性的影响,本文选用三种平均粒径分别为0.31、0.43和0.51 mm的聚乙烯颗粒(密度约为0.922 g/cm^(3))作为固相,改变混合浆体的流速及固相质量分数,测量浆体在水平圆管内流动的压降值,根据剪切应力与剪切速率的关系,确定了分段拟合流变方程的方法,分析了固相颗粒粒径大小对冰浆类固液两相流流变特性的影响。实验结果表明:混合浆体的剪切应力会随着颗粒粒径、固相质量分数以及剪切速率的增大而增大,浆体表现为剪切增稠流体,其流变指数总是大于1。在颗粒粒径不变的情况下,浆体的流变系数会随着固相质量分数的增大而增大。当固相质量分数较低小于15%,流变系数会随着粒径的增大而显著增大。

Ice slurry has been widely used in air conditioners,food,and other industries owing to its good performance in flow,heat transfer and cold storage.To study the effect of solid particle size on the rheological characteristics of ice slurry,three kinds of polyethylene particles(density about 0.922 g/cm^(3))with average particle sizes of 0.31 mm,0.43 mm,and 0.51 mm were selected as the solid phase in this study.The pressure drop of the mixed slurry flowing in a horizontal circular pipe was measured by changing its velocity and solid-phase content.A piecewise fitting rheological equation was determined based on the relationship between shear stress and shear rate.The effect of particle size on the rheological properties of two-phase liquid such as ice slurry was studied.The results show that the shear stress of the mixed slurry increases with increasing particle size,solid-phase content,and shear rate.The slurry behaves as a shear-thickening fluid,and its rheological index is always greater than 1.The rheological coefficient of the slurry increases with an increase in the solid-phase content under the condition of constant particle size.When the solid content is lower than 15%,the rheological coefficient increases significantly with increasing particle size.