120
8 Scaling-Up Enabling the Full Potential of Industrial …
the implementation of a temperature measurement is relatively accurate at the laboratory scale, in large scales, the energy loss due to air convection and medium/wall
interface should be taken into consideration by using a corrected model of calorimetric equation. In the intensification process, the measurement of power dissipation is
often correlated with the determination of the chemical activity induced by ultrasound
like KI method (Weissler reaction).
In the case where a purely chemical process is desired, it is preferable to rely on
luminescence mapping as described in Chap. 1. The emission of photons is monitored
by an ICCD camera whose exposure times depend on the mode of emission (the
exposure time is higher for sonoluminescence but the intensity is lower than for
sonochemiluminescence) (Cao et al. 2012). It should be noted that SCL spectra can
be recorded with a fibre optics spectrofluorophotometer emerged in the sonoreator
to access at the quantification of fluorescence emission.
8.3.4 Modelling Cavitational Process
In order to provide experimental data, the knowledge of the spatial distribution of
bubble collapse allows to better understanding the physics of cavitation especially in
large reactors. Indeed, the control of the cavitation field in the volume to be treated
is a guarantee of success of the extrapolation of the chemical engineering system
and the contribution of the modelling of bubble dynamic may help in predicting the
cavitational activity. For this purpose, the computational models developed for the
understanding of the distribution of collapse bubbles and the improvement of the
mechanical properties of the transducers are compared with the experimental data
collected by the types of measurement mentioned elsewhere.
The bubble dynamics and spatio-temporal variations can be modelled by using
Rayleigh-type equations in order to predict the pressure and temperature after the
bubble collapse as well as the radius of pulsation and their lifetime (Jamshidi et al.
2012). However, when the pressure amplitude increases, the cavitation phenomenon
becomes highly non-linear (bubble oscillations, acoustic wave) which involves the
use of models incorporating its considerations must be used as shown by the latest
developments in this field (Louisnard 2012; Vanhille and Campos-Pozuelo 2014).
Furthermore, the finite element method (FEM), due to the integration of both time
domain and spatial domain, has become the most widely used methodology in the
field of piezoelectric transducer innovation, numerical investigation of inhomogeneous bubble clouds and scaling-up investigations (Perincek et al. 2009).
8.4 Conclusion
Cavitation reactions are very effective tools for the intensification of processes in
terms of reaction yields and energy saving especially for certain types of high valueadded applications. The scale-up is more complex and costly for ultrasonic cavitation
8 Scaling-Up Enabling the Full Potential of Industrial …
the implementation of a temperature measurement is relatively accurate at the laboratory scale, in large scales, the energy loss due to air convection and medium/wall
interface should be taken into consideration by using a corrected model of calorimetric equation. In the intensification process, the measurement of power dissipation is
often correlated with the determination of the chemical activity induced by ultrasound
like KI method (Weissler reaction).
In the case where a purely chemical process is desired, it is preferable to rely on
luminescence mapping as described in Chap. 1. The emission of photons is monitored
by an ICCD camera whose exposure times depend on the mode of emission (the
exposure time is higher for sonoluminescence but the intensity is lower than for
sonochemiluminescence) (Cao et al. 2012). It should be noted that SCL spectra can
be recorded with a fibre optics spectrofluorophotometer emerged in the sonoreator
to access at the quantification of fluorescence emission.
8.3.4 Modelling Cavitational Process
In order to provide experimental data, the knowledge of the spatial distribution of
bubble collapse allows to better understanding the physics of cavitation especially in
large reactors. Indeed, the control of the cavitation field in the volume to be treated
is a guarantee of success of the extrapolation of the chemical engineering system
and the contribution of the modelling of bubble dynamic may help in predicting the
cavitational activity. For this purpose, the computational models developed for the
understanding of the distribution of collapse bubbles and the improvement of the
mechanical properties of the transducers are compared with the experimental data
collected by the types of measurement mentioned elsewhere.
The bubble dynamics and spatio-temporal variations can be modelled by using
Rayleigh-type equations in order to predict the pressure and temperature after the
bubble collapse as well as the radius of pulsation and their lifetime (Jamshidi et al.
2012). However, when the pressure amplitude increases, the cavitation phenomenon
becomes highly non-linear (bubble oscillations, acoustic wave) which involves the
use of models incorporating its considerations must be used as shown by the latest
developments in this field (Louisnard 2012; Vanhille and Campos-Pozuelo 2014).
Furthermore, the finite element method (FEM), due to the integration of both time
domain and spatial domain, has become the most widely used methodology in the
field of piezoelectric transducer innovation, numerical investigation of inhomogeneous bubble clouds and scaling-up investigations (Perincek et al. 2009).
8.4 Conclusion
Cavitation reactions are very effective tools for the intensification of processes in
terms of reaction yields and energy saving especially for certain types of high valueadded applications. The scale-up is more complex and costly for ultrasonic cavitation