Correlation of liquid-side mass transfer coefficient based on the new concept of specific power group

Abstract A new concept of a specific power group, proposed previously for correlating the mass transfer between a liquid and particles fixed in the liquid with a low level of turbulence, is discussed in comparison with the conventional concept of a specific power group from the Kolmogoroff theory. The new concept gives a single correlation equation of liquid-side mass transfer coefficients for single particles, fixed beds, and fluidized beds, which is practically the same as the correlation equations for stirred tanks, suspended bubble columns, and two-phase tube flow based on the conventional concept. The agreement induces the consideration of the relationship between specific power groups based on the new concept and the conventional one from the viewpoint of hydrodynamics. The energy dissipation rate for a particle, defined in the new concept, is extended to the particles suspended in a fully developed turbulence field and is hydrodynamically compared with the average energy dissipation rate defined conventionally in the turbulence field. It is revealed that the magnitude of the specific power group including the former energy dissipation rate almost agrees with that including the latter one. Thus, combined with the specific power group based on the conventional concept which has a simplicity in the calculation of its value for suspended particles, the specific power group based on our concept is useful as a general parameter in the study of mass transfer phenomena between a liquid and particles where the liquid is either quiescent or turbulent and the particles are fixed or suspended.