Particle size effects on an optical fiber sensor response

• Published in: Powder technology Vol. 115; no. 1; pp. 68 - 74
• Main Authors: Bellino, I, Bergougnoux, L, Misguich-Ripault, J, Firpo, J.-L
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 07-03-2001; Elsevier
• Subjects: Applied sciences; Chemistry; Circuit properties; Colloidal state and disperse state; Electric, optical and optoelectronic circuits; Electronics; Emulsions and suspensions; Exact sciences and technology; Fundamental areas of phenomenology (including applications); General and physical chemistry; Imaging detectors and sensors; Integrated optics. Optical fibers and wave guides; Optical and optoelectronic circuits; Optical elements, devices, and systems; Optical fiber sensor; Optics; Particle concentration; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Physics; Sensors, gyros; Specific area; Particle concentration; Optical fiber sensor; Specific area; Monte Carlo method; Volume fraction; Backscattering; Particle suspension; Experimental study; Fluid solid; Fiber optic sensors; Concentration measurement; Particle size distribution; Size effect; Optical method; Monodispersed particle; Numerical simulation; Polydispersed particle
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/S0032-5910(00)00278-3

Optical fiber sensors based on the light backscattered by particles are widely used to measure the volume fraction of suspensions. But all the users know that particle size influences the sensor response. In this paper, this particle size effect is studied for one sensor geometry (a central emitting fiber and two crowns of receiving fibers). An electronic device gives an output voltage in terms of the ratio of light intensities collected by each crown. Experimental results obtained with several suspensions, spherical glass beads and silica particles suspended in water, are scaled on a single curve in terms of the
C/
d
3,2 ratio.
C is the volume fraction and
d
3,2 the Sauter mean diameter, also called volume surface diameter, characteristic of size particle distribution. This single curve is validated for various particle size distributions by calculating the sensor response with Monte Carlo simulation when the particles are spherical, weakly absorbent and their size greater than the light wavelength. So, the validity range of this curve is: 0.1≤
C≤0.4 with 7 μm<
d
3,2<25 μm. A possible application of this result is the study of size segregation during the sedimentation of a concentrated suspension, if the concentration is measured by other means (for instance by an acoustic device).