| 1. |
- Akbarnejad, Shahin, 1978-, et al.
(författare)
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A Computational Fluid Dynamics Study on Physical Refining of Steel Melts by Filtration
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, a previous experimental investigation on physical refining of steel melts by filtration was numerically studied. To be specific, filtration of non-metallic alumina inclusions, in the size range of 1 to 100 [μm], from steel melt by using a square-celled monolithic alumina filter was simulated. Computational fluid dynamics (CFD) studies, including simulations of both fluid flow and particle tracing using one-way coupling method, were conducted. The CFD predicted results for particles in the size range 5 [μm] were compared to the published experimental data. The modelled filtration setup could capture 100 % of the particles larger than 50 [μm]. The percentage of the filtered particles decreases from 98% to 0% in the particle size range of 50 [μm] to 1[μm].
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| 2. |
- Akbarnejad, Shahin, 1978-, et al.
(författare)
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A Computational Fluid Dynamics Study on Physical Refining of Steel Melts by Filtration
- 2023
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Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 13:6
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a previous experimental investigation on physical refining of steel melts by filtration was numerically studied. To be specific, the filtration of non-metallic alumina inclusions, in the size range of 1-100 & mu;m, was stimulated from steel melt using a square-celled monolithic alumina filter. Computational fluid dynamics (CFD) studies, including simulations of both fluid flow and particle tracing using the one-way coupling method, were conducted. The CFD predicted results for particles in the size range of & LE;5 & mu;m were compared to the published experimental data. The modeled filtration setup could capture 100% of the particles larger than 50 & mu;m. The percentage of the filtered particles decreased from 98% to 0% in the particle size range from 50 & mu;m to 1 & mu;m.
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| 3. |
- Akbarnejad, Shahin, et al.
(författare)
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An investigation on permeability of ceramic foam filters (CFF)
- 2015
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Ingår i: TMS Light Metals. - Hoboken, NJ, USA : Wiley. - 9781119082446 ; , s. 949-954, s. 949-954
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Konferensbidrag (refereegranskat)abstract
- CFFs are used to filter liquid metal in the aluminum industry. CFFs are classified in grades or pores per inch (PPI), ranging from 10-100 PPI. Their properties vary in everything from pore and strut size to window size. CFFs of 80-100 PPI are generally not practical for use by industry, as priming of the filters by gravitational forces requires an excessive metal head. Recently, co-authors have invented a method to prime such filters using electromagnetic Lorentz forces, thus allowing filters to be primed with a low metal head. In the continuation of this research work, an improved experimental setup was developed in the present study to validate previous results and to measure the permeability of different filters, as well as a stack of filters. The study of permeability facilitates estimation of the required pressure drop to prime the filters and the head required to generate a given casting rate.
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| 4. |
- Akbarnejad, Shahin, et al.
(författare)
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Analysis on Experimental Investigation and Mathematical Modeling of Incompressible Flow Through Ceramic Foam Filters
- 2016
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer. - 1073-5615 .- 1543-1916. ; 47:4, s. 2229-2243
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents experimental results of pressure drop measurements on 30, 50, and 80 pores per inch (PPI) commercial alumina ceramic foam filters (CFF) and compares the obtained pressure drop profiles to numerically modeled values. In addition, it is aimed at investigating the adequacy of the mathematical correlations used in the analytical and the computational fluid dynamics (CFD) simulations. It is shown that the widely used correlations for predicting pressure drop in porous media continuously under-predict the experimentally obtained pressure drop profiles. For analytical predictions, the negative deviations from the experimentally obtained pressure drop using the unmodified Ergun and Dietrich equations could be as high as 95 and 74 pct, respectively. For the CFD predictions, the deviation to experimental results is in the range of 84.3 to 88.5 pct depending on filter PPI. Better results can be achieved by applying the Forchheimer second-order drag term instead of the Brinkman-Forchheimer drag term. Thus, the final deviation of the CFD model estimates lie in the range of 0.3 to 5.5 pct compared to the measured values.
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| 5. |
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| 6. |
- Akbarnejad, Shahin, et al.
(författare)
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Effect of Batch Dissimilarity on Permeability of Stacked Ceramic Foam Filters and Incompressible Fluid Flow : Experimental and Numerical Investigation
- 2022
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Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 12:6, s. 1001-
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic foam filters (CFFs) are used to remove inclusions and/or solid particles from molten metal. In general, the molten metal poured on the top of a CFF should reach a certain height to form the pressure (metal head) required to prime the filter. For estimating the required metal head and obtaining the permeability coefficients of the CFFs, permeability experiments are essential. Recently, electromagnetic priming and filtration of molten aluminum with low and high grades of CFF, i.e., 30, 50 and 80 pore per inch (PPI) CFFs, have been introduced. Since then, there has been interest in exploring the possibility of obtaining further inclusion entrapment and aluminum refinement by using electromagnetic force to prime and filter with stacked CFFs. The successful execution of such trials requires a profound understanding concerning the permeability parameters of the stacked filters. Such data were deemed not to exist prior to this study. As a result, this study presents experimental findings of permeability measurements for stacks of three 30, three 50 and three 80 PPI commercial alumina CFFs from different industrial batches and compares the findings to numerically modelled data as well as previous research works. Both experimental and numerical findings showed a good agreement with previous results. The deviation between the experimentally and numerically obtained data lies in the range of 0.4 to 6.3%.
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| 7. |
- Akbarnejad, Shahin, et al.
(författare)
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Effect of Fluid Bypassing on the Experimentally Obtained Darcy and Non-Darcy Permeability Parameters of Ceramic Foam Filters
- 2017
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer. - 1073-5615 .- 1543-1916. ; 48:1, s. 197-207
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic foam filters (CFFs) are used to remove solid particles and inclusions from molten metal. In general, molten metal which is poured on the top of a CFF needs to reach a certain height to build the required pressure (metal head) to prime the filter. To estimate the required metal head, it is necessary to obtain permeability coefficients using permeametry experiments. It has been mentioned in the literature that to avoid fluid bypassing, during permeametry, samples need to be sealed. However, the effect of fluid bypassing on the experimentally obtained pressure gradients seems not to be explored. Therefore, in this research, the focus was on studying the effect of fluid bypassing on the experimentally obtained pressure gradients as well as the empirically obtained Darcy and non-Darcy permeability coefficients. Specifically, the aim of the research was to investigate the effect of fluid bypassing on the liquid permeability of 30, 50, and 80 pores per inch (PPI) commercial alumina CFFs. In addition, the experimental data were compared to the numerically modeled findings. Both studies showed that no sealing results in extremely poor estimates of the pressure gradients and Darcy and non-Darcy permeability coefficients for all studied filters. The average deviations between the pressure gradients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 57.2, 56.8, and 61.3 pct. The deviations between the Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples found to be 9, 20, and 31 pct. The deviations between the non-Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 59, 58, and 63 pct.
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| 8. |
- Akbarnejad, Shahin, 1980-
(författare)
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Experimental and Mathematical Study of Incompressible Fluid Flow through Ceramic Foam Filters
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ceramic Foam Filters (CFFs) are widely used to filter solid particles and inclusions from molten metal in metal production, particularly in the aluminum industry. In general, the molten metal is poured on the top of a ceramic foam filter until it reaches a certain height, also known as metal head or gravity head. This is done to build the required pressure to prime the filter media and to initiate filtration. To predict the required metal head, it is necessary to obtain the Darcy and non-Darcy permeability coefficients of the filter. The coefficients vary upon filter type. Here, it is common to classify CFFs based on grades or pore per inches (PPI). These CFFs range from10 to100 PPI and their properties vary in everything from cell and window size to strut size. The 80-100 PPI CFFs are generally not practical for use by industry, since the priming of the filters by a gravitational force requires an excessive metal head. However, recently a new method has been developed to prime such filters by using electromagnetic Lorentz forces. This allows the filters to be primed at a low metal head.To continue the research work, it was deemed necessary to measure the pressure gradients of single and stack of commercial alumina ceramic foam filters and to obtain the permeability characteristics. Therefore, efforts have been made to validate the previously obtained results, to improve the permeametry experimental setup, and to obtain Darcy and non-Darcy permeability coefficients of single 30, 50, and 80 PPI filters and stacks of filters. Furthermore, the experimentally obtained pressure gradients were analyzed and compered to the mathematically and analytically estimated pressure gradients.The studies showed that, in permeametry experiments, the sample sealing procedure plays an important role for an accurate estimation of the permeability constants. An inadequate sealing or an un-sealed sample results in an underestimation of the pressure drop, which causes a considerable error in the obtained Darcy and non-Darcy permeability coefficients. Meanwhile, the results from the single filter experiments showed that the permeability values of the similar PPI filters are not identical. However, the stacks of three identical filters gave substantially the same measured pressure drop values and roughly the same Darcy and non-Darcy coefficients as for the single filters.The permeability coefficients of the filters are believed to be best defined and calculated by using the Forchheimer equation. The well-known and widely used Ergun and Dietrich equations cannot correctly predict the pressure drop unless a correction factor is introduced. The accuracy of the mathematically estimated pressure drop, using COMSOL Multiphysics® 5.1, found to be dependent on the drag term used in the Brinkman-Forchheimer equation. Unacceptable error, as high as 84 to 89 percent for the 30, 50 and 80 PPI single filters, compared to the experimentally obtained pressure gradient values were observed when the literature defined Brinkman-Forchheimer drag term was used. However, when the same second order drag term (containing the non-Darcy coefficient) as defined in the Forchheimer equation was used, the predicted pressure gradient profiles satisfactorily agreed with the experiment data with as little as 0.3 to 5.5 percent deviations for the 30, 50 and 80 PPI single filters.
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| 9. |
- Akbarnejad, Shahin, 1978-
(författare)
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Mathematical and Experimental Study on Filtration of Solid Inclusions from Molten Aluminium and Steel
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aluminum and steel have been the most produced metal and alloy, respectively, for many years. Their extensive use in various industries, their fundamental role in our everyday life, and their excellent recycling characteristics are the major driving forces for development of their production towards more sustainable processes. A successful integration and application of molten metal filtration from unwanted inclusions in production processes could result in reducing scrap, rework and would provide a cleaner molten metal which could lead to production of metallic materials with enhanced mechanical properties. Filtration of aluminum melts by ceramic foam filters is an established process in aluminum industry. Ceramic filters are also used in steel foundries to remove inclusions from the melt prior to casting to the mold. However, the use of ceramic filters is either limited to specific types of alloys or casts or to specific filters with large pores and openings. As a result, utilization of ceramic filters in the steel industry has limitations in capturing inclusions, where specifically small size inclusions may not be captured. This research work aims at contributing to the global effort in developing the molten metal production processes to become more sustainable and to increase the quality of the final product. To be specific, it is aimed at shedding more light into filtration applications and the use of ceramic filters for removal of solid non-metallic inclusions from molten aluminum and steel. Thus, permeability characteristics of single 30, 50, and 80 Pore Per Inch (PPI) alumina Ceramic Foam Filter (CFF) grades as well as stacks of three 30, three 50, and three 80 PPI alumina CFF grades were both experimentally and numerically obtained and studied. This provides the information needed to estimate the pressure required to prime and/or push the molten aluminum through the filters. The pressure could either be built up by gravitational or other forces. It has been shown recently that it is possible to prime such filters with electromagnetic forces and filter solid inclusions from molten aluminum. Lastly, physical refining of molten steel from solid alumina inclusions through monolithic extruded square-celled alumina ceramic filter was investigated and studied with a developed mathematical Computational Fluid Dynamics (CFD) model as well as the particle trajectories of inclusions in the size range of 1 to 100 [µm]. The experimentally obtained permeability characteristics as well as the obtained pressure gradient profiles of the single 30, 50, and 80 PPI CFFs were compared to previous research findings from the literature. Overall, a good agreement between the current and previous findings was found. It was also shown that fluid bypassing should be avoided during permeability experiments, otherwise deviations as high as 60% may occur. It was also revealed that similar permeability characteristics for the stacked filters, compared to single filters, could be achieved. However, an about three times higher pressure gradient or pressure needs to be applied when using a stack of three identical PPI filters compared to using single filters. The numerical simulations also validated the experimental findings of the permeability experiments. The CFD simulations and particle trajectories of the solid alumina inclusions in molten steel through the monolithic alumina filter revealed that it was possible to capture all particles larger than 50 [µm]. However, it was not possible to capture all particles smaller than 50 [µm] due to the applied simulation approach as well as current simulation limitations in the software.
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| 10. |
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