[Triumf-seminars] TRIUMF Seminar today at 15:00

[TRIUMF Seminars]

Date/Time: Wed 2017-07-19 at 15:00

Location:  Auditorium          

Speaker:   Sanja Miskovic (UBC)

Title:     3D Particle Tracking in Dense Turbulent Multiphase Flows using PEPT and RPT techniques

Abstract: Multiphase flows – flows with at least two distinct phases – are ubiquitous in nature and are critical for a multitude of industrial processes such as production of fuels, chemicals and pharmaceuticals, food and bio-tech products, and minerals, metals, and materials, among many others. Despite such a wide usage, our understanding of dynamics of multiphase flows and reactors is still very limited. This is mostly due to our inability to accurately measure and describe the local structure of multiphase flows. The lack of detailed structural and dynamic information at both micro- and macro-scales, together with mathematical difficulties in describing spatial and temporal randomness of the multiphase media, make the application of the models based on the first principles very difficult. Furthermore, the use of high temperatures and pressures during the conversion and handling of highly viscous materials and dense slurries yield to extreme processing conditions for which process hydrodynamics is extremely complex and hard to describe through models. Hence, development and application of experimental techniques, which are capable of non-intrusive measurement and monitoring of complex multiphase flow fields, are critical for accurate characterization and modelling of flows and transport phenomena in multiphase systems.

Availability of fast analog-to-digital converters and new data acquisition systems, together with highly sensitive radiation detectors, have led to the development of two radiotracing techniques – radioactive particle tracking (RPT) and positron emission particle tracking (PEPT) – allowing highly accurate non-intrusive mapping of complex 3D flow fields in real-time. Both techniques aim to track one or more radio-labelled tracer particles, each representing one or more phases in the system. PEPT uses a circular array of positron-sensitive detectors placed around the monitored system, which is tailored to detect pairs of back to back gamma rays resulting from the annihilation of a positron. RPT employs an array of scintillator detectors, which can be flexibly arranged around different system geometries, where the position of the gamma-emitting radiotracer particles with respect to time can be investigated by determining the amount of radiation sensed by each detector. Since RPT and PEPT use different detectors and rely on different algorithms to reconstruct tracer trajectories, they have their own advantages and drawbacks. For instance, RPT setups are compact, flexible and cheap compared to those of PEPT. In this presentation, the current state of the PEPT and RPT technologies will be outlined.



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