182 Fermentation and Biochemical Engineering Handbook Table 1. Classification of Mixing Processes Physical Processing Application Classes Chemical Processing Liquid-Solid Dissolving Absorption Emulsions Immiscible Liquids Extract Blending Miscible Liquids Reactions Fluid motion Heat Transfer The other types of processes involve more complicated extensions of fluid shear rates and the determination of which mixing variables are most important. This normally involves experimental measurements to find out exactly the process response to these variables which are not easy to visualize and characterize in terms of fluid mechanics In order to discuss the various levels of complexity and analysis ofthese mixing systems, some of the fluid mechanics of mixing impellers are examined and then examples of how these are used in actual cases are shown 2.0 PUMPING CAPACITY AND FLUID SHEAR RATES All the power, P, applied to the systems produces a pumping capacity, 2, and impeller head, H, shown by the equation P∝OH g has the units of kilograms per second and h has the units of Newton meters per second. Power then would be in watts The power, P, drawn by mixing impellers in the low and medium182 Fermentation and Biochemical Engineering Handbook Table 1. Classification of Mixing Processes Physical Processing Application Classes Chemical Processing Suspension Liquid-Solid Dissolving Dispersions Liquid-Gas Absorption Emulsions Immiscible Liquids Extraction Blending Miscible Liquids Reactions Pumping Fluid Motion Heat Transfer The other types of processes involve more complicated extensions of fluid shear rates and the determination of which mixing variables are most important. This normally involves experimental measurements to find out exactly the process response to these variables which are not easy to visualize and characterize in terms of fluid mechanics. In order to discuss the various levels of complexity and analysis ofthese mixing systems, some of the fluid mechanics of mixing impellers are examined and then examples of how these are used in actual cases are shown. 2.0 PUMPING CAPACITY AND FLUID SHEAR RATES All the power, P, applied to the systems produces a pumping capacity, Q, and impeller head, H, shown by the equation: PccQH Q has the units of kilograms per second and H has the units of Newton meters per second. Power then would be in watts. The power, P, drawn by mixing impellers in the low and medium viscosity range is proportional to: P cc N3D5