Pascal Debreyne

Ultrasonic Adhesion Measurement of Whey Protein Fouling

The knowledge of milk deposit adhesion is a prerequisite for setting innovative operating conditions of processing and strategies of cleaning. Unfortunately, these data are lacking because few methods of characterization of the adhesion quality exist. In this work, an ultrasonic method toward the quantification of the adhesion of a fouling dairy deposit onto a stainless-steel surface is proposed. The method is based on the investigation of the shear waves reflection at the interface between deposit and substrates. First, the associated theory for quantifying adhesion by a reflection coefficient is introduced and the ultrasonic method proposed is briefly presented. Then, experiments led with glucose syrups of various viscosities and different substrates (glass and stainless steel) for validating the adhesion parameter values are described and results are compared to classical tests for measuring adhesion strength. Finally, some preliminary trials for measuring the adhesion of a whey protein fouling onto coated stainless steel were carried out and discussed.

Inline high frequency ultrasonic particle sizer

This paper reports the development of a new method of particle sizing in a liquid. This method uses high frequency focused ultrasounds to detect particles crossing the focal zone of an ultrasonic sensor and to determine their size distribution by processing the reflected echoes. The major advantage of this technique compared to optical sizing methods is its ability to measure the size of particles suspended in an opaque liquid without any dedicated sample preparation. Validations of ultrasonic measurements were achieved on suspensions of polymethyl methacrylate beads in a size range extending from a few micrometer to several hundred micrometer with a temporal resolution of 1 s. The inline detection of aggregate formation was also demonstrated.

Contribution of the shear wave ultrasonic reflectometry to the stickiness measurements

HIGHLIGHTSShear wave reflection coefficient is used for stickiness evaluation.This non‐invasive testing method is fully described from sensor to signal processing.Evaluation of the adhesion of fluids is tested for 6 decades of viscosity range.Influence of the normal force on the adhesion of two solids is studied.Measurements are correlated with more traditional indicators. ABSTRACT Today, non‐invasive quantification of the adhesion of a deposit to a surface is always a challenge and, unfortunately, few tools are available in this area. This is an obstacle, in several industrial processes, to the identification of conditions limiting the fouling and to the establishment of eco‐efficient cleaning strategies. In this paper, a non‐invasive ultrasonic technique was developed in the aim of characterizing the adhesion of viscoelastic fluids or solid deposited on a substrate. We adopted the idea that the more a deposit is difficult to clean the more adherent it is. From this point of view the value of the reflection coefficient of an ultrasonic shear wave informs us about the adhesion of the deposit on a surface. A large bibliography on the adhesion measurement is given. Then the principle of ultrasonic test is presented and cares required for the measurement of the reflection coefficient are widely discussed. The ultrasonic reflection coefficients obtained with different controlled samples covering a wide range of interfaces (liquid/substrate, solid/substrate) are presented and compared with other indicators of adhesion. All the data on various samples showed that the ultrasonic test is a tool to discriminate non‐destructively a large range of interface quality, allowing ranking according to the adhesive strength.