Performance of a non-contact handling device using swirling flow with various gap height

Vortex levitation can achieve non-contact handling by blowing air into a vortex cup through a tangential nozzle to generate a swirling flow. In this paper, we focused on the relationship between the sucking pressure and the flow dynamics when gap distance from the cup to a work piece changes. Then simultaneous measurement of a pressure and a flow field in the cup was performed. As a result, the mean pressure changes and the pressure fluctuation inside the cup enhances with increasing gap height. Especially, periodic pressure perturbation is observed with wide gap height and it synchronizes with an eccentric rotation of the swirling flow. It is also found that the rotation axis of swirling flow steadily inclines against the central axis of the cup for appropriate gap height.ArticleJOURNAL OF VISUALIZATION. 13(4):319-326 (2010)journal articl

Suppression of Vortex Precession in a Non-Contact Handling Device by a Circular Column

Vortex levitation attains non-contact handling by injecting air through a tangential nozzle into a cylindrical cup generating the swirling flow. The precessing of the swirling flow causes pressure fluctuation. This phenomenon becomes apparent as the gap between the cup and workpiece increases, which significantly disturbs the stability of conveyance. In this paper, suppression of pressure fluctuation by a cylindrical column that stabilizes the vortex levitation is described and its mechanism is mentioned. According to the experimental set up, the pressure was measured at the center of the workpiece and the wall of the cup; velocity field under the work piece was visualized by PIV. The result suggested that the larger diameter column denoted the effect on suppression of the fluctuation because the precessing of the swirling flow became stable. On the other hand, variation of the column thickness had insignificant effect on suppressing the fluctuation, but sucking force became weakened since the swirling velocity decreased.ArticleJournal of Flow Control, Measurement & Visualization. 4:70-78 (2016)journal articl

Suppression of Vortex Precession in a Non-Contact Handling Device by a Circular Column

Vortex levitation attains non-contact handling by injecting air through a tangential nozzle into a cylindrical cup generating the swirling flow. The precessing of the swirling flow causes pressure fluctuation. This phenomenon becomes apparent as the gap between the cup and workpiece increases, which significantly disturbs the stability of conveyance. In this paper, suppression of pressure fluctuation by a cylindrical column that stabilizes the vortex levitation is described and its mechanism is mentioned. According to the experimental set up, the pressure was measured at the center of the workpiece and the wall of the cup; velocity field under the work piece was visualized by PIV. The result suggested that the larger diameter column denoted the effect on suppression of the fluctuation because the precessing of the swirling flow became stable. On the other hand, variation of the column thickness had insignificant effect on suppressing the fluctuation, but sucking force became weakened since the swirling velocity decreased

Thermochemical conversion of biomass in a Swirling Fluidized Bed: a design procedure and numerical simulation

Process intensification of biomass conversion as a route to a low-carbon manufacturing industry pursues novel solutions able to achieve safe, cost-efficient, energy-efficient, and environment-friendly processes. Implementation of process intensification in gas-solid operations enhances mass, heat, and momentum transfer rates, while develops multifunctional equipment to increase production capacity per size of installation. The Swirling Fluidized Bed reactor is a gas-solid contacting device that replaces the Earth's gravitational field with a centrifugal field generating a centrifugal bed that achieves more uniform beds, higher transfer rates, and shorter processing times than conventional fluidized beds. However, there is a gap of research in two points: a binary-phase numerical simulation to study both gas and solid hydrodynamics, and the constructive design of the swirling fluidized bed reactor related to expected operating conditions. In the present work, a design procedure of swirling fluidized beds for thermochemical conversion of biomass is proposed. The study of the swirling fluidized bed reactor comprises three stages: a systematic literature review, a numerical simulation of the reactor, and the development of the design procedure. The simulation gives insight of the SFB reactor operation useful for the decision making during early stages of design. Thermochemical and mechanical models together with technical procedures are used for the reactor design. The proposed design shows good agreement with an operational reactor used for rice husk combustion.MaestríaMagister en Ingeniería Mecánic

AN INVESTIGATION OF A NOVEL GAS-SOLID SEPARATOR FOR DOWNER REACTORS

Rapid gas-solid separation is a critical stage in many industrial applications, such as fluid k *- lytic cracking (FCC), heavy oil upgrading, and biomass pyrolysis. In these applications, act gases must be separated quickly and efficiently from catalyst or heat-bearing particles to srminate cracking reactions. Several rapid separation devices have been proposed to achieve sse demands. However, most proposed designs were intended for FCC processes. Very few gas-solid separators have been proposed specifically for biomass pyrolysis. A novel gas-solid separator for biomass pyrolysis in a downer reactor is investigated in this jesis. An experimental study is performed to identify important separator geometry and operating conditions. Computational fluid dynamics (CFD) is used to gain insight into the two- shase flow structure in the separator. The numerical results are coupled with an original ^experimental technique for measuring the particle-wall restitution coefficient to select !appropriate materials for the separator’s internal surface

Microfluidic Nanoparticles Focusing and Separation

Focusing and separation of bionanoparticles, such as HIV virus, is a critical step in clinical diagnosis. However, it often requires sophisticated infrastructure that is not easily accessible in resource limited environment. Microfluidics is a promising solution to biological sample processing and diagnostics at the point of need because the ability to use very small quantities of samples and reagents, and to carry out separations and detections with high resolution and sensitivity; low cost; short time for analysis; and small footprints for the analytical devices. By studying migration of nanoparticles by gravity or temperature gradient, we designed devices that can focus and separate nanoparticles.Clinical analysis of acute viral infection in blood requires the separation of viral particles from blood cells, since cytoplasmic enzyme inhibits the subsequent viral detection. To facilitate this procedure in settings without access to a centrifuge, we present a microfluidic device to continuously purify bionanoparticles from cells based on their different intrinsic movements on the microscale. Also, lateral flow introduced by gravity which serves as key for particle separation was quantified.Enriching nanoparticles, both biological and synthetic in a solution, is commonly practiced for various applications. A general method to focus nanoparticles in a microfluidic channel in a label free and continuous flow fashion is not yet available, due to a dominant Brownian force on the nanoscale. Recent research of thermophoresis indicates that thermophoretic force can overcome Brownian force to direct nanoparticle movement. Coupling thermophoresis with natural convection on the microscale has been shown to induce significant enrichment in a closed capillary. However, the sample volume and throughput are not practical, due to difficulty to control thermophoretic and the naturally convective transport independently, and the concentrated samples are hard to retrieve. We designed a microfluidic device to couple artificial recirculation with thermophoresis which allows effective nanoparticle focusing and continuous sample retrieval from the outlet. Numerical analysis studies how the microfluidic geometry and flow condition controls the focusing effect. The results demonstrate that the ratio between the thermophoretic and convective fluxes governs the concentration factor, which reaches maximum when the ratio is approximate one. Microfluidic device was also designed and assembled to reveal the physical processes behind the concentration phenomena and show nanoparticles focusing by one order of magnitude

STUDY OF HYDRODYNAMIC PROPERTIES OF SWIRLING FLUIDIZED BED

The Swirling Fluidized Bed (SFB) being a newer version of the well-known bubbling fluidized bed, a physical insight into its working, operating regimes and relationship with various aspects need to be investigated. Although some studies have been conducted on SFB in the past, a thorough understanding of the science of the process is yet to be arrived at. Since previous studies on SFB show promise of a highly effective alternative for contemporary techniques and immense potential for commercialization, a comprehensive study on the various aspects controlling the hydrodynamics of the swirling fluidized bed has been carried out

Centrifugal separation for cleaning well gas streams : from concept to prototype

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Process development using oscillatory baffled mesoreactors

PhD ThesisThe mesoscale oscillatory baffled reactor (meso-OBR) is a flow chemistry platform whose niche is the ability to convert long residence time batch processes to continuous processes. This reactor can rapidly screen reaction kinetics or optimise a reaction in flow with minimal waste. In this work, several areas were identified that could be addressed to broaden the applicability of this platform. Four main research themes were subsequently formulated and explored: (I) development of deeper understanding of the fluid mechanics in meso-OBRs, (II) development of a new hybrid heat pipe meso-OBR for improved thermal management, (III) further improvement of continuous screening using meso-OBRs by removing the solvent and employing better experiment design methodologies, and (IV) exploration of 3D printing for rapid reactor development. I. The flow structures in a meso-OBR containing different helical baffle geometries were studied using computational fluid dynamics simulations, validated by particle image velocimetry (PIV) experiments for the first time. It was demonstrated, using new quantification methods for the meso-OBR, that when using helical baffles swirling is responsible for providing a wider operating window for plug flow than other baffle designs. Further, a new flow regime resembling a Taylor-Couette flow was discovered that further improved the plug flow response. This new double vortex regime could conceivably improve multiphase mixing and enable flow measurements (e.g. using thermocouples inside the reactor) to be conducted without degrading the mixing condition. This work also provides a new framework for validating simulated OBR flows using PIV, by quantitatively comparing turbulent flow features instead of qualitatively comparing average velocity fields. II. A new hybrid heat pipe meso-OBR (HPOBR) was prototyped to provide better thermal control of the meso-OBR by exploiting the rapid and isothermal properties of the heat pipe. This new HPOBR was compared with a jacketed meso-OBR (JOBR) for the thermal control of an exothermic imination reaction conducted without a solvent. Without a solvent or thermal control scheme, this reaction exceeded the boiling point of one of the reactants. A central composite experiment design explored the effects of reactant net flow rate, oscillation intensity and cooling capacity on the thermal and chemical response of the reaction. The HPOBR was able to passively control the temperature below the boiling point of the reactant at all conditions through heat spreading. Overall, a combined 260-fold improvement in throughput was demonstrated compared to a reactor requiring the use of a solvent. Thus, this ii wholly new reactor design provides a new approach to achieving green chemistry that could be theoretically easily adapted to other reactions. III. Analysis of in situ Fourier transform infrared (FTIR) spectroscopic data also suggested that the reaction kinetics of this solventless imination case study could be screened for the first time using the HPOBR and JOBR. This was tested by applying flow-screening protocols that adjusted the reactant molar ratio, residence time, and temperature in a single flow experiment. Both reactor configurations were able to screen the Arrhenius kinetics parameters (pre-exponential factors, activation energies, and equilibrium constants) of both steps of the imination reaction. By defining experiment conditions using design of experiments (DoE) methodologies, a theoretical 70+% reduction in material usage/time requirement for screening was achieved compared to the previous state-of-the-art screening using meso-OBRs in the literature. Additionally, it was discovered that thermal effects on the reaction could be inferred by changing other operating conditions such as molar ratio and residence time. This further simplifies the screening protocols by eliminating the need for active temperature control strategies (such as a jacket). IV. Finally, potential application areas for further development of the meso-OBR platform using 3D printing were devised. These areas conformed to different “hierarchies” of complexity, from new baffle structures (simplest) to entirely new methods for achieving mixing (most complex). This latter option was adopted as a case study, where the passively generated pulsatile flows of fluidic oscillators were tested for the first time as a means for improving plug flow. Improved plug flow behaviour was indeed demonstrated in three different standard reactor geometries (plain, baffled and coiled tubes), where it could be inferred that axial dispersion was decoupled from the secondary flows in an analogous manner to the OBR. The results indicate that these devices could be the basis for a new flow chemistry platform that requires no moving parts, which would be appealing for various industrial applications. It is concluded that, for the meso-OBR platform to remain relevant in the next era of tailor-made reactors (with rapid uptake of 3D printing), the identified areas where 3D printing could benefit the meso-OBR should be further explored

Energy efficient engine diffuser/combustor model technology

A full scale, full annular diffuser/combustor model test rig was tested to investigate how configurational changes affect pressure loss and flow separation characteristics. The rig was characterized by five major modules: inlet; prediffuser; strut; simulated combustor; and full combustor. The prediffuser featured a short, curved wall dump design. Performance goals included: (1) a separation-free prediffuser flow field; (2) total pressure loss limited to 3.0 percent in the prediffuser and shrouds; and (3) an overall section pressure loss of 5.5 percent P sub T3 at the design airflow distribution. The results indicated that the prediffuser configurations operate well within the program goals for pressure loss and demonstrate separation free operation over a wide range of inlet conditions