Industrial application of ultrasound based in-line rheometry: Visualization of steady shear pipe flow of chocolate suspension in pre-crystallization process

Abstract

In the present work an in-line ultrasonic method for investigation of the rheological flow behavior of concentrated suspensions was created. It is based on a nondestructive rheological measuring technique for pilot plant and industrial scale applications. Elsewhere the author discusses a tremendous need for in-line rheological characterization of highly concentrated suspensions exposed to pressure driven shear flow conditions. Most existing on-line methods are based on destructive macro actuators, which are not suitable for materials with sensitive to applied deformation structure. Since the process of our basic interest influences the structure of suspension it would be difficult to separate the effects of rheometric measurement and weakly pronounced structural changes arising from a fine adjustment of the process parameters. The magnitude of these effects is usually associated with the complex flow dynamics of structured liquids and is sensitive to density or temperature fluctuations around the moving rheometric actuator. Interpretation of the results of such measurements can be hindered by process parameter influences on liquid product structure. Therefore, the author introduces an in-line noninvasive rheometric method, which is implemented in a pre-crystallization process of chocolate suspension. Use of ultrasound velocity profile pressure difference (UVP-PD) technique enabled process monitoring of the chocolate pre-crystallization process. Influence of seeded crystals on Rheology of chocolate suspension was recorded and monitored on line. It was shown that even slight velocity pulsations in chocolate mainstream can strongly influence rheological properties besides influencing flow velocity profiles. Based on calculations of power law fit in raw velocity profiles and calculation of wall shear stress from pressure difference measurement, a viscosity function was calculated and monitored on line. On-line results were found to be in a good agreement with off-line data. The results of the industrial test of the UVP-PD system brought practical knowledge and stipulated further development of a Smart UVP-PD noninventive on-line rheometer.

Rheometry for non-Newtonian fluids

“…In recent years, there has been a growing interest in the use of non-invasive methods involving magnetic resonance imaging, MRI ( McCarthy et al ., 1992 ;Li et al ., 1994 ;Arola et al , 1997 ;Gibbs et al , 1997 ;Goloshevsky et al , 2005) , ultrasound Doppler velocimetry ( Roberts, 2001 ;Greenwood and Bamberger, 2002 ;Ouriev et al , 2003 ;Brunn et al , 2004 ;Pfund et al , 2006 ) and LDA (laser doppler anemometer) techniques. The MRI technique employs two magnetic fi eld gradients, one in the direction of fl ow and the other in the direction normal to the fl ow.…”

Nonintrusive In-Line Rheometry Using Ultrasonic Velocity Profiling

“…Different rheology models were chosen depending on the test fluids, and the rheological properties were determined also by function fitting on the velocity profiles measured by UVP. The UVP-PD method has been used for various fluids, such as suspensions, , tomato sauce, cocoa butter, , viscoelastic surfactant solution, and cement grouts. , The method has been advanced by monitoring of the speed of sound through the test fluid to ensure highly accurate measurement of the velocity profile and using an optimized transducer to reduce the lack of the velocity profile data near the wall . The latter approach achieves a clamp-on technology, which allows nonintrusive measurement of the velocity profiles for industrial applications.…”

In‐line Monitoring of Tomato Concentrate Physical Properties During Evaporation

“…2002), fat suspension (Ouriev et al . 2000), precrystallized fluid chocolate (Ouriev et al . 2003), suspensions (Ouriev and Windhab 2002, 2003) and body lotion (Brunn et al .…”