Particle Size Analysis презентация

Particle Size Analysis

Particle size

Particle size from image analysis

Radius of Gyration

Diameters can vary, exercise

Particle size- equivalent diameters

More diameters Volume diameter – diameter of sphere having same volume Obtained from Coulter counter techniques Surface volume diameter – diameter of sphere having same surface to volume ratio Obtained from permeametry (measuring pressure drop with flow through a packed bed) Mobility diameter – diameter equal to the diameter of a sphere having the same mobility in an electric field as particle

Concept of fractal dimension Aerosol particles which consist of agglomerates of ‘primary particles’, (often, combustion generated) may be described using the concept of fractals. Fractals - The relationship between radius r (rgyration usually) of aerosol agglomerates, and the volume of primary particles in the agglomerate can be written:

Fractal dimension

Particle Size Con’t Particle concentration – suspensions in air Particle density – powders What if particles are not all the same size? Size distribution – discrete and continuous Number, volume and mass based distributions Frequency distributions Histogram tricks Single modes – different types of averaging Moments

Particle concentration

Mass and Volume Concentrations

Particle concentrations - powders

What if we have a mixture of particles of different sizes?

Continuous particle size distributions

More continuous size distributions

What do they look like?

Frequency distributions

More on size distributions

Spreadsheet tricks

Number, mass, surface area distributions not the same!

Describing distributions using a single number, a.k.a. what is average?

Standard shapes of distributions

Similarity transformation

Self-preserving size distribution

Moments of the distribution function