This paper proposes the use of an angle of mixedness 0 to characterize the full range of micromixing. By use of the general environment model with a constant 0, it is found that the conversion for a state of intermediate mixedness could be higher than the conversions incurred in the two extreme limits of micromixing, namely, complete segregation and maximum mixedness. This applies to all reactions, including unimolecular first order reactions, with zero order reactions as the only exception.
HOMOGENEOUS reactions taking place inside continuous flow reactors are in general influenced by both the macromixing and micromixing of the reactive fluids. Whereas macromixing refers to the residence time distribution of the molecules, micromixing is concerned with the environments surrounding these molecules during their stay in the reactor.
The groundwork for the theory of micromixing was laid by Danckwerts [3] and Zwietering [9]. Danckwerts introduced the concept of a point which contains many molecules and yet is small compared to the scale of segregation. He used the age distribution of the various points to characterize the degree of segregation. Thus he defined the state of complete segregation for a well-stirred tank reactor. Zwietering introduced the life expectation distribution in addition to the age distribution. He defined a state of maximum mixedness as an antithesis of the state of complete segregation. In this way, he extended Danckwerts' treatment to reactors with arbitrary residence time distributions.
While Danckwerts and Zwietering treated the two extreme limits of micromixing, namely, complete segregation and maximum mixedness, the two-environment model of Ng and Rippin[4,63 dealt with reactors of intermediate mixedness. They postulated that there are only two environments inside a reactor. One is the entering en-