| 1. |
- Akbarnejad, Shahin, et al.
(författare)
-
Analysis on Experimental Investigation and Mathematical Modeling of Incompressible Flow Through Ceramic Foam Filters
- 2016
-
Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer. - 1073-5615 .- 1543-1916. ; 47:4, s. 2229-2243
-
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.
|
|
| 2. |
- Akbarnejad, Shahin, 1980-
(författare)
-
Experimental and Mathematical Study of Incompressible Fluid Flow through Ceramic Foam Filters
- 2016
-
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.
|
|
| 3. |
- Aune, Ragnhild Elizabeth, et al.
(författare)
-
Experimental designs toward an understanding of process phenomena in steelmaking
- 2006
-
Ingår i: Iron and Steel Technology. - 1547-0423. ; 3:12, s. 137-146
-
Tidskriftsartikel (refereegranskat)abstract
- Various experimental studies towards the understanding of different process phenomena in iron and steelmaking were presented. Thermal diffusivity measurement was carried out at various temperature to monitor the structural changes occurring in coke. X-ray diffraction measurements were carried out to determine the average crystallite size of graphite along the structural c-axis and in the structural ab plane. It was observed that the apparent thermal diffusivity during the cooling cycle is larger than the heating cycle. Many experiments were also conducted in a high-temperature x-ray diffraction unit, to study the rate of graphitization at any given temperature for a given coke sample. An experimental design for the investigation of the mechanism of reduction in the blast furnace shaft, and the role of coke by dynamic x-ray photography was also carried out. The heating and melting of a mold flux during continuous casting were also simulated in specially designed laboratory.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Aune, Ragnhild Elizabeth, et al.
(författare)
-
Thermodynamic Aspects of Metals Processing
- 2005
-
Ingår i: Fundamentals of Metallurgy. - : Woodhead Publishing Limited. - 1855739275 - 978 1 85573 927 7 ; , s. 38-81
-
Bokkapitel (refereegranskat)
|
|
| 8. |
- Björling, Gunilla, et al.
(författare)
-
Long-Term Tracheostomy : Aspects on Tube Change and Material Wear
- 2007
-
Konferensbidrag (refereegranskat)abstract
- The tracheostomy tubes in use are exposed not only to bacteria but also the lining fluids, which are a first defence against toxicity in inhaled gases. It contains several antioxidants. The complex bacteriological environment in the trachea, as well as the formation of a biofilm on the tube surface through colonization of bacteria, is believed to affect the mechanical and chemical properties of the tube material. The study was conducted at the National Respiratory Centre (NRC) at Danderyd Hospital in collaboration with the Royal Institute of Technology and Sophiahemmet University College in Stockholm, Sweden.
|
|
| 9. |
- Fritzsch, R., et al.
(författare)
-
A novel method for automated quantification of particles in solidified aluminium
- 2014
-
Ingår i: TMS 2014 143rd Annual Meeting & Exhibition, Annual Meeting Supplemental Proceedings. - Hoboken, NJ, USA : The Minerals, Metals, and Materials Society. - 9781118889725 ; , s. 535-543
-
Konferensbidrag (refereegranskat)abstract
- Particle concentration and size distribution in the melt can give important information regarding the filtration efficiency and the quality of the aluminium. LiMCA (Liquid Metal Cleanliness Analyser) system, used in primary and secondary production of aluminium, provides in-situ data for granulometric and total density information on the inclusion content, but has problems quantifying particles < 20 μm in size. To be able to determine the required cleanliness with particle counts down' to 10 μm for modern alloys a novel method for automated quantitative results has been developed. Results are obtained using a user friendly technique based on the ImagePro® Plus 7.0 software. The different image processing steps adopted for automated quantification of the particle count in a size range from 2 to 50 μm is described and discussed together with the obtained results. The automated technique has been benchmarked elsewhere with a manual particle count reviling an error of ∼3% on the overall filtration efficiency.
|
|
| 10. |
- Fritzsch, R., et al.
(författare)
-
Automated quantification of SiC-particles in solidified A356 aluminium using ImagePro® plus 7.0
- 2013
-
Ingår i: TMS Annu Meet. - 9781118605646 ; , s. 69-77
-
Konferensbidrag (refereegranskat)abstract
- The quantitative particle concentration can give important information about the cleanliness of melts for quality control in primary and secondary production of aluminum. Manual quantification of the particle concentration is normally a time consuming process and human control can bias the acquired images and particle count. The present paper explains the automated image-processing steps for the quantification of SiC-particles, with equivalent diameters from 2 to 25 μm, in solidified A356. A total of 700 micrographs, acquired with a standard white light microscope with 10 x magnification, were analyzed. The applied software (Image Pro-Plus 7.0 from MediaCybernetics®) allows for programming of macros which in turn provides the user with a higher degree of control. The automated results are compared with the results obtained by manually counting the particles in the same micrographs. The impact of the automated results on the estimated filtration efficiency was established to be only ∼3%.
|
|
