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Experimental investigation on micromixing characteristics of coaxial mixers in viscous system
Author(s) -
Liu Baoqing,
Gao Pengfei,
Sun Ning,
Zhang Yikun,
Jin Zhijiang,
Sunden Bengt
Publication year - 2020
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.23730
Subject(s) - impeller , micromixing , rushton turbine , coaxial , turbine , rotational speed , mechanics , power consumption , materials science , power (physics) , mechanical engineering , acoustics , physics , engineering , composite material , thermodynamics , viscosity
An experimental investigation into the micromixing performance of coaxial mixers in a viscous system is reported, in which the iodide‐iodate reaction system is chosen to quantitatively characterize the product distributions. The effects of feeding time, feeding position, impeller speed, inner impeller configuration, and operation mode on the segregation index, X s, are examined. It is revealed that the feeding near the inner impeller benefits micromixing and should be regarded as the preferred position. The presence of the rotating outer impeller causes the micromixing performance of the coaxial mixer to be significantly better than the single‐shaft mixer. While an increase in the outer impeller speed has a limited influence on micromixing, the inner impeller speed is the dominant influencing factor, that is, the X s decreases obviously when the inner impeller speed is increased. On the other hand, the coaxial mixers with multiple and axial inner impellers have a better micromixing performance at the same specific power consumption, P V , than that with single and radial inner impellers. Among the configurations consisting of a Rushton impeller (RT), six‐straight‐blade turbine impeller (SBT), and six‐pitched (45°)‐blade turbine impeller (PBT), the X s of the coaxial mixer is always the smallest at the same P V when the PBT + RT configuration is used as the inner impeller. In addition, it is found that the difference in X s that results from various operation modes is small in terms of power consumption; however, the co‐rotation mode is still recommended for the micromixing of the coaxial mixer due to its excellent performance in general.