Non-isothermal micromixing in turbulent liquids: Theory and experiment

Jerzy Robert Bałdyga , John R. Bourne , Benedikt Walker


Partial segregation of reagents occurs when reaction rates exceed mixing rates and frequently causes product distributions to be mixing-dependent. A simultaneous temperature segregation, whereby the temperature in a reaction zone differs from that in its surroundings, has rarely been considered when mixing reagents in the liquid phase. The Prandtl number is usually sufficiently small that engulfment, not thermal conduction, determines the local temperature. The engulfment model of micromixing can then be extended by a heat balance to specify this temperature. To evaluate this model, a new pair of fast competitive reactions (neutralisation and acetal hydrolysis) has been characterised thermochemically and kinetically. A Mettler RC1 calorimeter was operated under isothermal and adiabatic conditions with various stirrer speeds and HCl was slowly added to a mixture of NaOH and 2,2-dimethoxypropane. Measured hydrolysis yields compared quite well with the extended engulfment model, although temperature segregation was of minor importance. It was also unimportant in other reaction systems (simultaneous neutralisation and ester hydrolysis; diazo coupling) employed earlier to study micromixing. Suggestions for further work are made.
Author Jerzy Robert Bałdyga ZIDRCh
Jerzy Robert Bałdyga,,
- Department of Chemical Reactor Engineering and Dynamics
, John R. Bourne
John R. Bourne,,
, Benedikt Walker
Benedikt Walker,,
Journal seriesCanadian Journal of Chemical Engineering, ISSN 0008-4034
Issue year1998
Publication size in sheets0.5
Keywords in Englishcompetitive reactions, micromixing, selectivity, semibatch reactor, temperature segregation, turbulent mixing
Languageen angielski
Bałdyga J. (i in.) - Non-isothermal micromixing....pdf 932.97 KB
Score (nominal)20
Publication indicators WoS Impact Factor: 2006 = 0.48 (2) - 2007=0.666 (5)
Citation count*43 (2015-03-28)
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