Averaged Diameters of a Particulate System

For a given size distribution, various averaged diameters can be calculated, depending on the forms of weighing factors. The selection of an appropriate averaged diameter of a particle system depends on the specific needs of the application. For instance, in a pulverized coal combustion process, the surface area per unit volume may be important. In this case, Sauter s averaged diameter should be chosen. 

The arithmetic mean diameter d is the averaged diameter based on the number density function of the sample d is defined by 

The surface mean diameter ds is the diameter of a hypothetical particle having the same averaged surface area as that of the given sample ds is given by 

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