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Montecchio, F., Altimira, M., Andersson, A. & Engvall, K. (2019). Fluid dynamics modelling of UV reactors in advanced oxidation processes for VOC abatement applications. Chemical Engineering Journal, 369, 280-291
Open this publication in new window or tab >>Fluid dynamics modelling of UV reactors in advanced oxidation processes for VOC abatement applications
2019 (English)In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 369, p. 280-291Article in journal (Refereed) Published
Abstract [en]

The present work focuses on the treatment of VOC emissions from industrial processes, since they represent a very severe environmental hazard. For removing the VOC, an AOP (Advanced Oxidation Process) stage based on UV light and ozone was considered, analyzing the methods for the unit scale-up. An innovative CFD (Computational Fluid Dynamics) model, combining UV irradiation, reaction kinetics and fluid dynamics, describing the behavior of UV reactors in the laboratory scale, was developed. This model was verified against experimental results, displaying good agreement. Therefore, we concluded the CFD model could adequately describe relevant features regarding the performance of UV reactors. After analyzing the laboratory reactors, two designed and scaled up prototypes, were simulated using the CFD model. While the first prototype has a standard lamps configuration, the second presents an innovative lamps distribution. As for the laboratory cases, the most relevant features in terms of irradiation and reaction were described for the prototypes, comparing their performance. We evaluated both the overall VOC conversion and VOC conversion per UV lamp, analyzing the energy efficiency of each configuration with adequately accuracy. Therefore, we conclude the developed CFD model to be an important tool for reactor scale-up as a result of the good prediction of experimental results and the accurate description of the governing phenomena. By using the developed model, the scale-up process of UV reactors can be quickly improved, by screening various configurations with the simulator before testing them, saving significant time and effort in the development of full-scale reactors.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2019
Keywords
CFD simulation, Reactor modelling, Reactor scale-up, Air treatment, UV reactor, VOC abatement
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-251191 (URN)10.1016/j.cej.2019.03.094 (DOI)000463344800029 ()2-s2.0-85062730612 (Scopus ID)
Note

QC 20190523

Available from: 2019-05-23 Created: 2019-05-23 Last updated: 2022-11-24Bibliographically approved
Kékesi, T., Altimira, M., Amberg, G. & Prahl Wittberg, L. (2019). Interaction between two deforming liquid drops in tandem and various off-axis arrangements subject to uniform flow. International Journal of Multiphase Flow, 193-218
Open this publication in new window or tab >>Interaction between two deforming liquid drops in tandem and various off-axis arrangements subject to uniform flow
2019 (English)In: International Journal of Multiphase Flow, ISSN 0301-9322, E-ISSN 1879-3533, p. 193-218Article in journal (Refereed) Published
Abstract [en]

A Volume of Fluid (VOF) method is applied to study the interaction between two liquid drops with the same initial diameter in uniform flow. Various arrangements of the drops are studied, based on two parameters, namely the initial separation distance and the angle between the line connecting the centres of the drops and the free-stream direction. Initial separation distances of 1.5–5 drop diameters, and angles between β=0 ∘ and 90° are considered. Simulations for a Weber number of We=20, two Reynolds numbers Re=20 and 50, and density and viscosity ratios in the range ρ * =20–80 and μ * =0.5–50 are performed. The movement of the secondary drop with respect to the primary drop, and estimates on the time required for the breakup of the secondary drop as compared to those observed for single drops are evaluated. It is found that the drops collide only in cases corresponding to the shortest initial displacements, while in others they deform and break up independently, similarly or identically to single drops. The same behaviour is reflected in the time required for breakup. Cases where the drops behave independently show breakup times close to those observed for single drops.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Breakup time, Drop, Interaction, Off-axis, Regime map, Tandem, Reynolds number, Break-up time, Drops
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-248149 (URN)10.1016/j.ijmultiphaseflow.2018.11.009 (DOI)000460717400014 ()2-s2.0-85059345769 (Scopus ID)
Note

QC 20190425

Available from: 2019-04-25 Created: 2019-04-25 Last updated: 2022-06-26Bibliographically approved
Heide, J., Karlsson, M. & Altimira, M. (2017). Numerical Analysis of Urea-SCR Sprays under Cross-Flow Conditions. Paper presented at 4 April 2017 through 6 April 2017. SAE technical paper series, 2017-March(March)
Open this publication in new window or tab >>Numerical Analysis of Urea-SCR Sprays under Cross-Flow Conditions
2017 (English)In: SAE technical paper series, ISSN 0148-7191, Vol. 2017-March, no MarchArticle in journal (Refereed) Published
Abstract [en]

Selective Catalytic Reduction (SCR) of NOx through injection of Urea-Water-Solution (UWS) into the hot exhaust gas stream is an effective and extensively used strategy in internal combustion engines. Even though actual SCR systems have 95-96% de-NOx efficiency over test cycles, real driving emissions of NOx are a challenge, proving that there is room for improvement. The efficiency of the NOx conversion is highly dependent on the size of UWS droplets and their spatial distribution. These factors are, in turn, mainly determined by the spray characteristics and its interaction with the exhaust gas flow. The main purpose of this study is to numerically investigate the sensitivity to the modelling framework of the evaporation and mixing of the spray upstream of the catalyst. The dynamics of discrete droplets is handled through the Lagrangian Particle Tracking framework, with models that account for droplet breakup and coalescence, turbulence effects, and water evaporation. All simulations have been run in the commercial code Ansys Fluent 16.0. Experimental validation of droplet size distribution is carried out through PDPA measurements. Through the present study we have identified suitable modelling setup that provides accurate results with a competitive computational cost. Results also show the importance of accounting for the effects of evaporation and turbulent fluctuations in the droplet phase.

Place, publisher, year, edition, pages
SAE International, 2017
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-216544 (URN)10.4271/2017-01-0964 (DOI)2-s2.0-85018420204 (Scopus ID)
Conference
4 April 2017 through 6 April 2017
Note

QC 20171108

Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2023-11-27Bibliographically approved
Olin, L., Altimira, M., Danielsson, J. & Rosén, A. (2017). Numerical modelling of spray sheet deflection on planing hulls. Journal of Engineering for the Maritime Environment (Part M), 231(4), 811-817
Open this publication in new window or tab >>Numerical modelling of spray sheet deflection on planing hulls
2017 (English)In: Journal of Engineering for the Maritime Environment (Part M), ISSN 1475-0902, E-ISSN 2041-3084, Vol. 231, no 4, p. 811-817Article in journal (Refereed) Published
Abstract [en]

This paper considers the modelling of spray formation on planing hulls. The focus is on assessing the applicability of the prevailing theories and two-dimensional and three-dimensional Computational Fluid Dynamics (CFD) simulations in the investigation of different design factors for a novel spray deflection concept. The spray deflection concept is presented and its performance is evaluated by comparison with traditional spray rails. It is found that the prevailing theory where the spray field of a planing hull is represented by a two-dimensional flat planing plate will overestimate the spray thickness, whereas the theories that are based on wedge impact are correlating well with the results from the CFD simulations. Compared to a bare hull, adding spray deflectors reduces the viscous resistance by 28% for the studied cases. The spray deflectors further redirect the spray aftwards which reduce the total drag an additional 4%. The paper also discusses various aspects on CFD modelling of spray formation.

Place, publisher, year, edition, pages
SAGE PUBLICATIONS LTD, 2017
Keywords
Planing hulls, spray formation, spray deflection, resistance reduction, CFD
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-217735 (URN)10.1177/1475090216682838 (DOI)000414468700001 ()2-s2.0-85032952538 (Scopus ID)
Note

QC 20171122

Available from: 2017-11-22 Created: 2017-11-22 Last updated: 2022-06-26Bibliographically approved
Altimira, M. & Casanueva, C. (2017). RAISING AWARENESS ON DIVERSITY AND EQUALITY IN STEM DEGREES IN HIGHER EDUCATION. In: Chova, LG Martinez, AL Torres, IC (Ed.), INTED2017: 11TH INTERNATIONAL TECHNOLOGY, EDUCATION AND DEVELOPMENT CONFERENCE. Paper presented at 11th International Conference on Technology, Education and Development (INTED), MAR 06-08, 2017, Valencia, SPAIN (pp. 1037-1041). IATED-INT ASSOC TECHNOLOGY EDUCATION A& DEVELOPMENT
Open this publication in new window or tab >>RAISING AWARENESS ON DIVERSITY AND EQUALITY IN STEM DEGREES IN HIGHER EDUCATION
2017 (English)In: INTED2017: 11TH INTERNATIONAL TECHNOLOGY, EDUCATION AND DEVELOPMENT CONFERENCE / [ed] Chova, LG Martinez, AL Torres, IC, IATED-INT ASSOC TECHNOLOGY EDUCATION A& DEVELOPMENT , 2017, p. 1037-1041Conference paper, Published paper (Refereed)
Abstract [en]

Higher education environments are becoming more and more diverse, regarding both gender and cultural background, which could pose significant challenges for both students and teachers. In order to raise the topic amongst STEM students, a lecture on Diversity has been implemented in the course Research Methodologies for Engineering Mechanics, where different concepts regarding equality have been introduced and unconscious bias have been explained to the students. The lecture was placed in the middle of the course so that students could reflect back on their previous evaluations and enable them to correct their biases in the second half of the course. Feedback of the whole course has also been compared between the 2016 and 2015 editions, where this lecture was not present. The results show that a lecture in Diversity and Equality is especially useful for female students, strongly supporting its inclusion in the course.

Place, publisher, year, edition, pages
IATED-INT ASSOC TECHNOLOGY EDUCATION A& DEVELOPMENT, 2017
Series
INTED Proceedings, ISSN 2340-1079
Keywords
higher education, diversity and equality, homosociality, unconscious bias, STEM
National Category
Educational Sciences
Identifiers
urn:nbn:se:kth:diva-217957 (URN)000413668601018 ()978-84-617-8491-2 (ISBN)
Conference
11th International Conference on Technology, Education and Development (INTED), MAR 06-08, 2017, Valencia, SPAIN
Note

QC 20171121

Available from: 2017-11-21 Created: 2017-11-21 Last updated: 2022-06-26Bibliographically approved
Casanueva, C. & Altimira, M. (2016). Course design oriented towards degree objectives in higher education. In: EDULEARN16 Proceedings: . Paper presented at 8th annual International Conference on Education and New Learning Technologies (pp. 1662-1669). IATED
Open this publication in new window or tab >>Course design oriented towards degree objectives in higher education
2016 (English)In: EDULEARN16 Proceedings, IATED , 2016, p. 1662-1669Conference paper, Published paper (Refereed)
Abstract [en]

The goal of engineering education is to facilitate the learning of technical knowledge and understanding, skills, and attitudes required by students to become successful engineers. In the Swedish higher education system, the qualifications for a master degree in engineering are listed in the Higher Education Ordinance. Such qualifications, also called Degree Objectives, have to be fulfilled on a programme level, that is, throughout all courses that form the programme. This requires a high level of communication and collaboration between all course responsibles and the programme coordinator. At the same time, it also restricts the freedom in the design of each individual course, as they all have fit into a 2-year-long educational puzzle. Designing courses from their conception with a view on fulfilling all the degree objectives would be more effective in terms of programme coordination. However, it poses new challenges, since it requires that all degree objectives related to skills and attitudes be fulfilled in each and every course through its learning activities. Is there a way of designing the course activities in such a way that most degree objectives are covered, while respecting the diversity in learning styles and maturity level of the students, and promoting self-regulation? We explore the possibilities of this course design concept when framed within the CDIO Initiative. We analyse the relative importance of the different Degree Objectives in Swedish Higher Education, and how these can be introduced in the Intended Learning Outcomes of each individual course while keeping in mind the personal evolution of the students at different stages of their education.

Place, publisher, year, edition, pages
IATED, 2016
Keywords
higher education, course design, degree objectives, cdio
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-197908 (URN)10.21125/edulearn.2016.1330 (DOI)000402955901105 ()
Conference
8th annual International Conference on Education and New Learning Technologies
Note

QC 20161212

Available from: 2016-12-09 Created: 2016-12-09 Last updated: 2024-03-18Bibliographically approved
Nygård, A., Altimira, M., Prahl Wittberg, L. & Fuchs, L. (2016). Disintegration Mechanisms of Intermittent Liquid Jets. SAE International Journal of Fuels and Lubricants, 9(1), 91-99
Open this publication in new window or tab >>Disintegration Mechanisms of Intermittent Liquid Jets
2016 (English)In: SAE International Journal of Fuels and Lubricants, ISSN 1946-3952, E-ISSN 1946-3960, Vol. 9, no 1, p. 91-99Article in journal (Refereed) Published
Abstract [en]

It has been observed that intermittent injection leads to improved spray characteristics in terms of mixing and gas entrainment. Although some experimental work has been carried out in the past, the disintegration mechanisms that govern the breakup of intermittent jets remain unknown. In this paper we have carried out a systematic numerical analysis of the breakup of pulsated jets under different injection conditions. More specifically, the duty cycle (share of active injection during one cycle) is varied, while the total cycle time is kept constant. The advection of the liquid phase is handled through the Volume of Fluid approach and, in order to provide an accurate, yet computationally acceptable, resolution of the turbulent structures, the implicit Large Eddy Simulation has been adopted. The results show that the primary disintegration results from a combination of stretching, collision and aerodynamic interaction effects. Moreover, there exists a strong coupling between stretching and collision as stretching makes the pulse thinner prior to the contact between pulses. In this work, the purpose is to study the collision contribution to breakup in terms of the near nozzle pulse disintegration rate. When approaching the low duty cycle limit, this effect is significant because of the lower liquid volume of the pulse. In contrast, for a high duty cycle, the stretching effect is limited and a wide tail region remains as an obstruction for following pulses. However, the integral momentum of the pulse is maintained to a larger degree that has an adverse effect on the outcome of the collision event.

Place, publisher, year, edition, pages
SAE International, 2016
Keywords
Liquids, Aerodynamic interactions, Disintegration rate, Implicit large Eddy simulations, Injection conditions, Intermittent injection, Spray characteristics, Stretching effect, Turbulent structures
National Category
Fluid Mechanics
Identifiers
urn:nbn:se:kth:diva-195060 (URN)10.4271/2016-01-0851 (DOI)000384916400010 ()2-s2.0-84983488600 (Scopus ID)
Note

QC 20161101

Available from: 2016-11-01 Created: 2016-11-01 Last updated: 2025-02-09Bibliographically approved
Wu, H., Brunberg, J., Altimira, M., Bratt, N., Nyberg, H., Cronhjort, A. & Peciura, J. (2016). Semi-Empirical CFD Transient Simulation of Engine Air Filtration Systems. SAE International Journal of Passenger Cars - Mechanical Systems, 9(1), 310-320
Open this publication in new window or tab >>Semi-Empirical CFD Transient Simulation of Engine Air Filtration Systems
Show others...
2016 (English)In: SAE International Journal of Passenger Cars - Mechanical Systems, ISSN 1946-3995, E-ISSN 1946-4002, Vol. 9, no 1, p. 310-320Article in journal (Refereed) Published
Abstract [en]

To improve fuel efficiency and facilitate handling of the vehicle in a dense city environment, it should be as small as possible given its intended application. This downsizing trend impacts the size of the engine bay, where the air filter box has to be packed in a reduced space, still without increased pressure drop, reduced load capacity nor lower filtering efficiency. Due to its flexibility and reduced cost, CFD simulations play an important role in the optimization process of the filter design. Even though the air-flow through the filter box changes as the dust load increases, the current modeling framework seldom account for such time dependence. Volvo Car Corporation presents an industrial affordable model to solve the time-dependent dust load on filter elements and calculate the corresponding flow behavior over the life time of the air filter box. The implemented semi-empirical simulation algorithm integrates several sub-models derived from different studies on flows over pleated filters. This work also introduces an experimental method to record the dust pattern on the filter element in order to validate the numerical results. Test results show that the overall dust load as well as its distribution within the filter element can be estimated accurately.

Place, publisher, year, edition, pages
SAE International, 2016
Keywords
Computational fluid dynamics, Crashworthiness, Dust, Efficiency, Engines, Numerical methods, Air filtration system, CFD simulations, Current modeling, Experimental methods, Filtering efficiency, Numerical results, Transient simulation, Volvo car corporations
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-195057 (URN)10.4271/2016-01-1368 (DOI)000383619500036 ()2-s2.0-84983514122 (Scopus ID)
Note

QC 20161103

Available from: 2016-11-03 Created: 2016-11-01 Last updated: 2024-03-18Bibliographically approved
Altimira, M. & Prahl Wittberg, L. (2016). Teaching Research Methodologies. In: INTED2016 Proceedings: . Paper presented at 10th annual International Technology, Education and Development Conference (INTED2016), Valencia, SPAIN, MAR 07-09, 2016 (pp. 3019-3027). IATED
Open this publication in new window or tab >>Teaching Research Methodologies
2016 (English)In: INTED2016 Proceedings, IATED , 2016, p. 3019-3027Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents the methodology employed in the Research Methodology course, part of the Master Program in Engineering Mechanics of the Royal Institute of Technology (KTH). As a higher education institution, KTH aims at excellence in both generation and dissemination of knowledge. Even though these two activities are traditionally seen as independent –or even mutually exclusive-, there is a positive correlation between performance in research andin pedagogical activities, reinforced by the fact that inquiry-based or researchbased learning activities enhance deep learning among the students. The course Research Methodology in Engineering Mechanics poses a unique opportunity to engage the students to research in different areas through diversity-oriented learning activities.The course’s main learning outcome is that the students become acquainted with the most common concepts and research methodologies used in the fields of Fundamental Mechanics, Solid Mechanics, Fluid Mechanics, Acoustics and Biomechanics. After the completion of the course, the student should also be able to identify and analyze the methodologies in a given published work.The course consists of 9 lectures and a group project, with an estimation of the total dedication time of 80h (3hp). One lecture is focused on research ethics;while in the other 8 researchers from KTH present their areas of expertise, introducing the most relevant methodologies applied. The attendance is about40 students.In the last two years, and based on the course assessment survey, the structure of the course has been continuously shifting from traditional lectures to cover a broader range of teaching activities. In this way, different learning styles are covered and the learning outcomes can be achieved by as many students as possible. In this regard, traditional lectures are combined with problem-based or case-based lectures, and role-play. Additionally, in the content of the lectures we also try to keep a balance between experimental and numerical research methods of the different disciplines, in such a way that the students get a holistic view of the research in that particular field.This project involves reading a research journal article in the subject of engineering mechanics and presenting, in written and oral form, a critical analysis of the methodologies employed. In the beginning of their project, the students give an oral presentation of their article to another group. At the end of this activity, each group is asked to mention a positive aspect of the presentation they just heard and something that they believe should be improved. As an additional task, each group is asked to peer-review another group’s report. To do so, the students are given a document with some guidelines and evaluation criteria. Special instructions are given to make sure positive feedback is also included in the review. With this, the students get to read the work of others, learn to apply quality criteria and give feedback, and self-reflect on their own work after the review process.

Place, publisher, year, edition, pages
IATED, 2016
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-197905 (URN)10.21125/inted.2016.1690 (DOI)000402738403007 ()978-84-608-5617-7 (ISBN)
Conference
10th annual International Technology, Education and Development Conference (INTED2016), Valencia, SPAIN, MAR 07-09, 2016
Note

QC 20161212

Available from: 2016-12-09 Created: 2016-12-09 Last updated: 2024-03-18Bibliographically approved
Altimira, M. & Fuchs, L. (2014). Effect of fuel flexibility on cavitation in injector-like flows. In: Proceedings of the 26th ILASS-Europe 2014: . Paper presented at 26th ILASS-Europe 2014, in Bremen.
Open this publication in new window or tab >>Effect of fuel flexibility on cavitation in injector-like flows
2014 (English)In: Proceedings of the 26th ILASS-Europe 2014, 2014Conference paper, Published paper (Refereed)
National Category
Fluid Mechanics
Identifiers
urn:nbn:se:kth:diva-159899 (URN)
Conference
26th ILASS-Europe 2014, in Bremen
Note

QC 20150211

Available from: 2015-02-11 Created: 2015-02-11 Last updated: 2025-02-09Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6242-4739

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