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Publications (10 of 86) Show all publications
Johansson, Ö., Pamidi, T. R., Shankar, V. & Löfqvist, T. (2019). Acoustic design principles for energy efficient excitation of a high intensity cavitation zone. In: Martin Ochmann (Ed.), Proceedings of the 23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019: ICA 2019, 9 - 13 September. Paper presented at 23rd International Congress on Acoustics (pp. 948-955). Aachen, Germany
Open this publication in new window or tab >>Acoustic design principles for energy efficient excitation of a high intensity cavitation zone
2019 (English)In: Proceedings of the 23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019: ICA 2019, 9 - 13 September / [ed] Martin Ochmann, Aachen, Germany, 2019, p. 948-955Conference paper, Published paper (Other academic)
Abstract [en]

Energy-efficient process intensification is a key aspect for a sustainable industrial production. To improve energy conversion efficiency high intensity cavitation is a promising method, especially in cases where the material to be treated is valuable and on the micro meter scale. Transient collapsing cavitation bubbles gives powerful effects on objects immersed in fluids, like cellulose fibers, mineral particles, enzymes, etc. The cavitation process needs optimization and control, since optimal conditions is multivariate challenge. This study focuses on different design principles to achieve high intensity cavitation in a specific volume in a continuous flow. This study explores some potential design principles to obtain energy efficient process intensification. The objective is to tune several different resonance phenomena to create a powerful excitation of a flowing suspension (two-phase flow and cavitation bubbles). The reactor is excited by sonotrodes, connected to two coupled resonant tube structures, at the critical frequency. Finally cavitation bubbles are initiated by a flow through a venturi nozzle. The acoustically optimised reactor geometry is modelled in Comsol Multiphysics®, and excited by dedicated ultrasound signals at three different frequencies. The effect of the high intensity cavitation is experimentally evaluated by calorimetric method, foil tests and degree of fibrillation on cellulose fibers.

Place, publisher, year, edition, pages
Aachen, Germany: , 2019
Keywords
Structural acoustics, Ultrasound, Hydrodynamics, Cavitation
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-76063 (URN)978-3-939296-15-7 (ISBN)
Conference
23rd International Congress on Acoustics
Funder
Swedish Energy Agency
Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-10-22
Pamidi, T. R., Johansson, Ö. & Löfqvist, T. (2019). Comparison of Cavitation Effect in Case of Fixed and Free Fibers in an Ultrasound Beaker. In: Martin Ochmann (Ed.), Proceedings of the 23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019: ICA 2019, 9 - 13 September. Paper presented at 23rd International Congress on Acoustics (pp. 8217-8224). Aachen, Germany
Open this publication in new window or tab >>Comparison of Cavitation Effect in Case of Fixed and Free Fibers in an Ultrasound Beaker
2019 (English)In: Proceedings of the 23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019: ICA 2019, 9 - 13 September / [ed] Martin Ochmann, Aachen, Germany, 2019, p. 8217-8224Conference paper, Published paper (Other academic)
Abstract [en]

In this study, we investigate the impact of high-intensity ultrasound treatment on the mechanical properties of pulp fibers. The pulp fiber samples are sonicated in an acoustically optimised beaker where high-intensity ultrasound is generated using a tuned sonotrode device. The idea is to create a controlled resonance to efficiently enhance the sound pressure in the beaker. Input power is 90Watt. The objective is to define the difference between freely suspended fibers in a beaker compared to keeping fibers in a fixed position. The hypothesis is that fiber treatment at a specific input power will be more efficient in the case when fibers are kept in a high pressure zone. Since the fiber wall is a layered structure, it is likely to delaminate internally which will affect the mechanical properties of the fiber. The effect on fiber properties is verified by measuring the ultrasound attenuation spectra for the treated fibers. The attenuation measurements are based on measurements of a low-intensity ultrasound pulse-echo technique. On a macroscopic scale, changes in the attenuation spectra relates to a change in mechanical properties of the fiber wall, since the suspended fibers more or less retain their diameter and length distributions.

Place, publisher, year, edition, pages
Aachen, Germany: , 2019
Keywords
Ultrasonics, Cavitation, Paper pulp, Cellulose fibers
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-76050 (URN)978-3-939296-15-7 (ISBN)
Conference
23rd International Congress on Acoustics
Funder
Swedish Energy Agency
Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2019-10-22
Pamidi, T. R., Johansson, Ö., Löfqvist, T. & Shankar, V. (2019). Comparison of Two Different Ultrasound Reactors for the Treatment of Cellulose Fibers. Ultrasonics Sonochemistry
Open this publication in new window or tab >>Comparison of Two Different Ultrasound Reactors for the Treatment of Cellulose Fibers
2019 (English)In: Ultrasonics Sonochemistry, ISSN 1350-4177Article in journal (Refereed) Epub ahead of print
Abstract [en]

The pulp and paper industry is in continuous need for energy-efficient production processes. In the refining process of mechanical pulp, fibrillation is one of the essential unit operations that count for up to 80% of the total energy use. This initial study explores the potential and development of new type of scalable ultrasound reactor for energy efficient mechanical pulping. The developed reactor is of continuous flow type and based on both hydrodynamic and acoustic cavitation in order to modify the mechanical properties of cellulose fibers. A comparison of the prototype tube reactor is made with a batch reactor type where the ultrasonic horn is inserted in the fluid. The pulp samples were sonicated by high-intensity ultrasound, using tuned sonotrodes enhancing the sound pressure and cavitation intensity by a controlled resonance in the contained fluid. The resonant frequency of the batch reactor is 20.8 kHz and for the tube reactor it is 22.8 kHz. The power conversion efficiency for the beaker setup is 25% and 36 % in case of the tube reactor in stationary mode. The objective is to verify the benefit of resonance enhanced cavitation intensity when avoiding the effect of Bjerkenes forces. The setup used enables to keep the fibers in the pressure antinodes of the contained fluid. In case of the continuous flow reactor the effect of hydrodynamic cavitation is also induced. The intensity of the ultrasound in both reactors was found to be high enough to produce cavitation in the fluid suspension to enhance the fiber wall treatment. Results show that the mechanical properties of the fibers were changed by the sonification in all tests. The continuous flow type was approximately 50% more efficient than the beaker. The effect of keeping fibers in the antinode of the resonant mode shape of the irradiation frequency was also significant. The effect on fiber properties for the tested mass fraction was determined by a low-intensity ultrasound pulse-echo based measurement method, and by a standard pulp analyzer

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
ultrasound reactor, hydrodynamic and acoustic cavitation, cellulose fiber properties
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Fluid Mechanics and Acoustics Paper, Pulp and Fiber Technology
Research subject
Electronic systems; Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-76606 (URN)10.1016/j.ultsonch.2019.104841 (DOI)31806547 (PubMedID)
Funder
Swedish Energy Agency, 166518
Available from: 2019-11-04 Created: 2019-11-04 Last updated: 2019-12-16
Pamidi, T. R., Johansson, Ö. & Löfqvist, T. (2019). Energy Efficient Fibrillation of Cellulose Fibers using an Ultrasound Reactor. In: : . Paper presented at Marcus Wallenberg Prize (MWP) Event 2019 – Young Researchers’ Challenge; October 6–9, 2019, Stockholm, Sweden.
Open this publication in new window or tab >>Energy Efficient Fibrillation of Cellulose Fibers using an Ultrasound Reactor
2019 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

The pulp and paper industry is in continuous need for energy-efficient production processes. Therefore, there is a focus in reducing electrical energy use in the production of paper.  The most energy demanding processes are related to fibrillation, which in some cases use up to 80% of required electrical power, with a net efficiency of 1%. The presented work focus on ultrasound controlled cavitation in concentrating the processing energy to provide an energy efficient development of cellulose fibers. The objectives are to develop a scalable cavitation reactor to obtain energy-efficient fibrillation of cellulose fibers aiming at reducing the energy use by 50%. Our goal is to develop a methodology based on multiphysic simulation for the design of an alternative refiner based on ultrasound cavitation. The reactor concept is of a flow through type where cavitation bubbles are initiated in the fiber suspension by the pressure release when the pulp flow through a venturi nozzle. The induced cavitation bubbles are collapsed by high intensity ultrasound at resonant frequencies. The collapsing bubbles and their associated shock waves modify the fiber wall properties which enables fibrillation.  Energy efficient fibrillation of cellulose fibers is therefore possible to achieve through an optimized combination of hydrodynamic and ultrasonic controlled cavitation. Initial results shows a positive effect on fiber quality. However, further optimization of process parameters like temperature and static pressure is required.

Keywords
Ultrasonic cavitation, Hydrodynamic cavitation, Cellulose fibers, Ultrasound reactor
National Category
Fluid Mechanics and Acoustics Paper, Pulp and Fiber Technology
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-76708 (URN)
Conference
Marcus Wallenberg Prize (MWP) Event 2019 – Young Researchers’ Challenge; October 6–9, 2019, Stockholm, Sweden
Funder
Swedish Energy Agency, 166518
Available from: 2019-11-14 Created: 2019-11-14 Last updated: 2019-11-27
Pamidi, T. R., Johansson, Ö. & Löfqvist, T. (2018). Comparison of Different Concepts of UltrasoundReactors Using Numerical Simulations. In: : . Paper presented at 16th Meeting of the European Society of Sonochemistry.
Open this publication in new window or tab >>Comparison of Different Concepts of UltrasoundReactors Using Numerical Simulations
2018 (English)Conference paper, Poster (with or without abstract) (Other (popular science, discussion, etc.))
Abstract [en]

Sonochemical reactors are used for process intensification based on efficientenergy transfer due to ultrasound in order to cause transient cavitation in the medium.Ultrasonic reactors are extensively used for numerous applications due to their differentfeatures. The process of ultrasound cavitation can be defined as generation, growth andviolent collapse of microbubbles under ultrasonic irradiation which can release a highamount of energy in a small volume. The released energy causes a sudden increase intemperature and pressure which thereby can lead to extensive process intensification. Thepresent work deals with the evaluation of two different configurations of ultrasound reactorsusing both numerical modeling and experimental verification. The evaluation is based onprediction of the pressure distribution, verified by foil tests and with calorimetric method.The two reactors were developed to be used for the treatment of cellulose fibers to improveenergy efficiency in the fibrillation process. The goal is to optimize cavitation intensityand minimize the coupling loss factors. The development and evaluation of these two reactorconcepts aim to improve the design methodology for a scalable flow through reactor conceptwith high yield and energy efficiency

National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-73782 (URN)
Conference
16th Meeting of the European Society of Sonochemistry
Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-09-06
Johansson, Ö., Pamidi, T. R. & Löfqvist, T. (2017). Design of a high-intensity ultrasound reactor. In: : . Paper presented at 2017 IEEE International Ultrasonics Symposium (IUS),Washington, DC, 6-9 Sept. 2017. Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Design of a high-intensity ultrasound reactor
2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Design, and optimization of ultrasonic reactors are important objectives in sonochemical processing. The recent expansion of the use of ultrasonic reactors in various research areas all faces the problem of scaling up from laboratory results to industrial purposes. A traditional ultrasonic reactor usually has several issues, such as low effectiveness as well as complex and unstable system performance, which all are unfavorable for efficient sonochemical processing. This study addresses these issues and investigates a new flow type ultrasonic reactor designed to generate transient cavitation as the main source for ultrasound. Some important factors like pressure, material, flow and geometry are considered in the design. Numerical optimization as well as experimental investigations are performed to reach an optimized, energy-efficient and controlled ultrasound cavitation reactor. Results from numerical modeling are used for acoustic optimization of the reactor, which is driven with three transducers mounted radially in the reactor wall with 120° spacing. The final reactor is excited with dual frequencies a total of 9 sonotrodes. The reactor is intended to be used in studies of pre-treatment of cellulose fibers aiming at developing an alternative, energy efficient fibrillation process and for ultrasound leaching of minerals.

Place, publisher, year, edition, pages
Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017
National Category
Fluid Mechanics and Acoustics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Acoustics; Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-66534 (URN)10.1109/ULTSYM.2017.8092948 (DOI)978-1-5386-3383-0 (ISBN)
Conference
2017 IEEE International Ultrasonics Symposium (IUS),Washington, DC, 6-9 Sept. 2017
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-24Bibliographically approved
Johansson, Ö., Pamidi, T. R. & Löfqvist, T. (2017). Design of a high-intensity ultrasound reactor. In: IEEE International Ultrasonics Symposium, IUS: . Paper presented at 2017 IEEE International Ultrasonics Symposium (IUS), Washington, DC, 6-9 Sept. 2017. Piscataway, NJ: IEEE Computer Society, Article ID 8091660.
Open this publication in new window or tab >>Design of a high-intensity ultrasound reactor
2017 (English)In: IEEE International Ultrasonics Symposium, IUS, Piscataway, NJ: IEEE Computer Society, 2017, article id 8091660Conference paper, Published paper (Refereed)
Abstract [en]

Design, and optimization of ultrasonic reactors are important objectives in sonochemical processing. The recent expansion of the use of ultrasonic reactors in various research areas all faces the problem of scaling up from laboratory results to industrial purposes. A traditional ultrasonic reactor usually has several issues, such as low effectiveness as well as complex and unstable system performance, which all are unfavorable for efficient sonochemical processing. This study addresses these issues and investigates a new flow type ultrasonic reactor designed to generate transient cavitation as the main source for ultrasound. Some important factors like pressure, material, flow and geometry are considered in the design. Numerical optimization as well as experimental investigations are performed to reach an optimized, energy-efficient and controlled ultrasound cavitation reactor. Results from numerical modeling are used for acoustic optimization of the reactor, which is driven with three transducers mounted radially in the reactor wall with 120° spacing. The final reactor is excited with dual frequencies a total of 9 sonotrodes. The reactor is intended to be used in studies of pre-treatment of cellulose fibers aiming at developing an alternative, energy efficient fibrillation process and for ultrasound leaching of minerals

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Computer Society, 2017
Series
IEEE International Ultrasonics Symposium, E-ISSN 1948-5719
National Category
Fluid Mechanics and Acoustics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Acoustics; Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-66533 (URN)10.1109/ULTSYM.2017.8091660 (DOI)000416948400055 ()2-s2.0-85039413569 (Scopus ID)978-1-5386-3383-0 (ISBN)
Conference
2017 IEEE International Ultrasonics Symposium (IUS), Washington, DC, 6-9 Sept. 2017
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2018-01-16Bibliographically approved
Johansson, Ö., Löfqvist, T. & Pamidi, T. R. (2017). Design of high-intensity ultrasound reactor. In: IEEE International Ultrasonics Symposium, IUS: . Paper presented at 2017 IEEE International Ultrasonics Symposium (IUS), Washington, DC, 6-9 Sept. 2017. Piscataway, NJ: IEEE Computer Society, Article ID 8092948.
Open this publication in new window or tab >>Design of high-intensity ultrasound reactor
2017 (English)In: IEEE International Ultrasonics Symposium, IUS, Piscataway, NJ: IEEE Computer Society, 2017, article id 8092948Conference paper, Published paper (Refereed)
Abstract [en]

Design and optmiziation of ultrasonic reactors are important objectives in sonochemical processing. The recent expansion of the use of ultrasonic reactors in various research projects all faces the problem of scaling up laboratory results for industrial use. A traditional ultrasonic reactor usually has several issues, such as low effectiveness and complex and unstable system performance, which all are unfavorable for efficient sonochemical processing. This study adresses these issues and investigates a new flow type ultrasonic reactor designed to generate transient cavitation as the main source for ultrasound for sonochemical processing. This study proposes the principle of the flow type ultrasonic reactor design to generate transient cavitation. The objective of this work is to design an ultrasonic reactor with a new geometry. The idea is to improve process efficiency based on resonance enhanced ultrasound controlled cavitation

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Computer Society, 2017
Series
IEEE International Ultrasonics Symposium, ISSN 1948-5719
National Category
Fluid Mechanics and Acoustics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Acoustics; Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-67244 (URN)10.1109/ULTSYM.2017.8092948 (DOI)000416948403005 ()2-s2.0-85039437533 (Scopus ID)978-1-5386-3383-0 (ISBN)
Conference
2017 IEEE International Ultrasonics Symposium (IUS), Washington, DC, 6-9 Sept. 2017
Available from: 2018-01-11 Created: 2018-01-11 Last updated: 2018-01-16Bibliographically approved
Johansson, Ö., Pamidi, T., Khoshkhoo, M. & Sandström, Å. (2017). Sustainable and energy efficient leaching of tungsten(W) by ultrasound controlled cavitation. Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Sustainable and energy efficient leaching of tungsten(W) by ultrasound controlled cavitation
2017 (English)Report (Other academic)
Abstract [en]

The project aims to use ultrasound controlled cavitation to achieve a more energy efficient leaching process. Locally, collapsing cavitation bubbles cause an extremely high pressure, shock waves and high temperature, which provide an opportunity to perform the leaching process at a much lower temperature than in an autoclave (20 bar overpressure and 220 ° C). The results show that the method works, but that a higher static pressure and thus temperatures are necessary to achieve a leaching recovery rate corresponding to today's autoclave technology. Another process parameter of importance is flow control and the initiation of cavitation bubbles that occur through a geometrically optimized nozzle (orifice plate). Numerical and experimental adaptation of the developed reactor with respect to the leaching conditions (Sodium hydroxide and Scheelite concentrate), required more time than expected. Best test results show that an energy supplement with ultrasonic controlled cavitation of 104 kWh / kg increases the leaching recovery by 21%. The leaching reagent temperature 60° C was determined regarding available reference data and was thought to be close to optimum for intensive cavitation in atmospheric pressure. Optimum temperature relates to the leaching reagent, vaporization temperature, density, boiling point, surface tension, and viscosity. Generally, for leaching is that higher temperatures are required to increase the chemical reaction rate (requires overpressure). The modified reactor principle provides stable results and is possible to scale up. Higher cavitation intensity for shorter finishing time and higher recovery rate require advanced flow induction, multiple excitation frequencies adapted to the optimized reactor geometry, as well as optimal process pressure and temperature.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2017. p. 20
Series
Research report / Luleå University of Technology, ISSN 1402-1528
Keywords
Ultrasound, Cavitation, Leaching, Scheelite, Vibro acoustic optimization
National Category
Mineral and Mine Engineering Fluid Mechanics and Acoustics Metallurgy and Metallic Materials
Research subject
Engineering Acoustics; Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-66286 (URN)978-91-7790-160-0 (ISBN)
Projects
Vinnova SIP-Strim
Funder
Vinnova, 2016-02620Vinnova
Available from: 2017-10-27 Created: 2017-10-27 Last updated: 2019-09-11Bibliographically approved
Wijaya, A. R. & Johansson, Ö. (2016). Difference thresholds of multi-axis whole-body vibration. In: IEEE International Conference on Industrial Engineering and Engineering Management: . Paper presented at 2016 International Conference on Industrial Engineering and Engineering Management, IEEM 2016, Bali, Indonesia,4-7 December 2016 (pp. 1760-1764). Piscataway, NJ: IEEE Computer Society, Article ID 7798180.
Open this publication in new window or tab >>Difference thresholds of multi-axis whole-body vibration
2016 (English)In: IEEE International Conference on Industrial Engineering and Engineering Management, Piscataway, NJ: IEEE Computer Society, 2016, p. 1760-1764, article id 7798180Conference paper, Published paper (Refereed)
Abstract [en]

A laboratory study was conducted to investigate the effects of lateral and horizontal vibration on the difference threshold of vertical vibration. Twelve male subjects sat on a rigid seat and were exposed to four different vibration conditions (pure vertical vibration; combination of horizontal and vertical vibration; combination of lateral and vertical vibration; combination of horizontal, lateral and vertical vibration). Vertical vibration for four conditions was 5 Hz sinusoidal with a magnitude of 1 ms-2 r.m.s. Horizontal and lateral vibration for the last three conditions were sinusoidal with magnitude 0.5 ms-2 r.m.s. and contained ten frequencies (1 to 8 Hz in third-octave band step). The frequency-weighted acceleration of the ten frequencies was equal. Results showed that horizontal and lateral vibrations have different effects on the difference threshold of vertical vibration. The combination of vertical and horizontal vibration gave a significantly lower difference threshold of vertical vibration than the combination of vertical and lateral vibration

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Computer Society, 2016
Series
IEEE International Conference on Industrial Engineering and Engineering Management, ISSN 2157-3611
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Acoustics
Identifiers
urn:nbn:se:ltu:diva-61851 (URN)10.1109/IEEM.2016.7798180 (DOI)000392208100357 ()2-s2.0-85009874493 (Scopus ID)9781509036653 (ISBN)
Conference
2016 International Conference on Industrial Engineering and Engineering Management, IEEM 2016, Bali, Indonesia,4-7 December 2016
Available from: 2017-02-07 Created: 2017-02-07 Last updated: 2017-11-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2955-2776

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