In Part 11, the extent to which dispersed-phase viscosity and interfacial tension influence equilibrium mean drop size and drop size distribution was determined for dilute suspensions produced in baffled cylindrical tanks of standard geometry equipped with six-blade Rushton turbines. Low to moderate viscosity (pd 5 0.5 Pa-s) dispersed-phase systems behaved similarly in that Sauter mean diameter could be correlated using the mechanistic arguments of Part I, and drop sizes, normalized with respect to D,z, could be correlated by a normal distribution in volume. Limited moderate viscosity data were reported in Part I but were not used to develop the correlations of Part 11. The objective of this study is to combine the low to moderate viscosity data of Parts I and I1 with those obtained by other investigators to obtain correlations of broader utility, and to extend these via mechanistic arguments so that they apply to nondilute systems. Dilute DispersionsSeveral investigators have studied the behavior of dilute liquid-liquid systems in the geometry of Parts I and I1 (see Figure 1 of Part I). Chen and Middleman (1967) conducted a detailed study of surface forced stabilized (low pd) dispersions encompassing a broad range of operating conditions. They considered dispersed phases with viscosities up to about 0.025 Pa. s but did not account for viscous resistance to breakage when correlating their data. Sprow (1967) NY.employed in these studies differed from that of Parts I and I1 in only two respects. Baffles were mounted flush to tank walls and bottom. Chen and Middleman varied the ratio of impeller to tank diameter ( L I T ) and Sprow obtained most of his data forFor dilute suspensions, coalescence rates are negligible. Equilibrium drop sizes are determined by breakup that occurs primarily in the impeller region. Small modifications in baffle placement should be relatively unimportant and the L/ T ratio should be of secondary importance. Chen and Middleman found that the effect of L/Tfell within the scatter in their data for the range 0.21 5 L / T 5 0.73. However, it should be noted that Okamot0 et al. (198 1) report that energy dissipation rates become more uniform as LIT increases. Therefore, the ratio of the maximum to mean energy dissipation rate per unit mass increases as L/ T decreases. For a given t, drops will experience higher local turbulent energy as LIT decreases, indicating that D,, should decrease with L f T. Mean drop size correlationsThe low to moderate viscosity data reported in Parts I and I1 and by the cited investigators were fit to models developed in Part 11. The range of variables investigated in each study is summarized in Table 1. The table provides Two models were fitted to the 349 data sets via nonlinear least-squares regression. These are the semitheoretical model LIT = 0.29.

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The use of the electrostatic classification method for sizing monodisperse 0.1 μm polystyrene latex (PSL) spheres has been investigated experimentally. The objective was to determine the feasibility of using electrostatic classification as a standard method of particle sizing in the development of a 0.1 μm particle diameter Standard Reference Material (SRM). The mean particle diameter was calculated from a measurement of the mean electrical mobility of the PSL spheres as an aerosol using an electrostatic classifier. The performance of the classifier was investigated by measuring its transfer function, conducting a sensitivity analysis to verify the governing theoretical relationships, measuring the repeatability of particle sizing, and sizing NIST SRM 1691, 0.269 μm and NIST SRM 1690, 0.895 μm particles. Investigations of the aerosol generator’s performance focused on the effect of impurities in the particle-suspending liquid on the resulting particle diameter.The uncertainty in particle diameter determined by electrical mobility measurements is found to be −3.3% to +3.0%. The major sources of uncertainty include the flow measurement, the slip correction, and a dependence of particle size on the aerosol flow rate. It was found that the classifier could be calibrated to indicate the correct size to within 0.1% for both SRM particle sizes if the defined classification length is decreased by 1.9%.

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