Conductivity of dispersions

Of the numerous equations proposed [84] to describe the conductivity of suspensions (k), one is cited here for illustration. The Bruggeman equation gives, 

Several other researchers [85,86] have developed similar equations that fit the general form  

Further discussion of suspension conductivity and some practical examples for solids concentration determination, and for suspensions flowing in pipelines, are given elsewhere [85,86]. 

Further discussion of emulsion conductivity and some practical examples for emulsions flowing in pipelines are given in [85], 

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Numerical procedures for calculating the conductivity of dispersions without restriction to double layer thickness were developed by O Brien. " A formula for thin EDL, exphcitly accounting for the ion mobility, is given by Ohshima et al. ... 

Experimental studies by Dukhin et al [14] showed that the specific electric conductance of disperse system depends on the frequency of applied field. These findings can be explained by changes in polarization effects at high frequencies. 

DeLaRue47 follow the same line at low void fractions but, beginning between void fractions of 0.1 and 0.2, DeLaRue s conductivities of dispersions containing spheres of various sizes are consistently lower than both Meredith s conductivities and DeLaRue s own conductivities of dispersions of monosized spheres. For example, note the difference at a void fraction of 0.4 where the conductivities of DeLaRue s dispersion of spheres of various sizes are lower than the conductivities of dispersions of monosize spheres. 

R. E. DeLaRue, Electric conductivity of dispersed systems, Master s thesis, University of California, Berkeley, 1955. 

Simonova, T.S. and Shilov, V.N., Influence of the mobilities of the ions in the compact part of the electric double layer of spherical particles on the electrophoresis and electric conductivity of disperse... 

The enhanced conductance of dispersions of titania with respect to the acid solution is illustrated in Fig. 4. 

Figure 5 The conductance of dispersions of titania in solutions of oxalic acid in 40 % ethanol...

Summerfield S (1985) Universal low-frequency behavior in the ac hopping conductivity of dispersed systems. Philos Mag B 52 9-22... 

Fridce HA (1924) A mathematical treatment of the electrk conductivity of disperse systems. Phys Rev 24 12-15... 

Thermal heat conductivity of dispersed phase in fluidized bed/packed bed at static state (kW/m K)... 

Experimental data for random dispersions of spheres of unequal sizes come from DeLaRue who, using the same techniques discussed in the previous section, experimented with multisized dispersions of glass spheres. The data used in this comparison also include data previously discussed and other data for which the size distribution was not specified. Clark experimented with foams and thus obtained data at very high void fractions. He used alternating current at 1 kHz in the experiments. Slawinski used alternating current techniques to measure the conductivity of dispersions of castor oil in a mixture of gum arabic and O.OS N KCl. Because his data deviate from the other data and do not follow Maxwell s equation at low void fractions, they must be suspect. Neale and Nader investigated conduction through packed spheres... 

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