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1. Dissolution of Microalloying Elements in a Ladle Metallurgy Furnace

   https://doi.org/10.3390/met13020421  

   Duruiheme, Ogochukwu Queeneth; Guo, Xipeng; Walla, Nicholas; Zhou, Chenn (February 2023, Metals)

   Industrial fusion of microalloying elements in steelmaking is imperative in defining and optimizing certain steel properties due to their strengthening and significant grain refinements effects at minute quantities. Copper, vanadium, and columbium are explored in this investigation to monitor their respective dissolution processes in a ladle metallurgy furnace (LMF), with concise parametric studies on effects of number of plugs and variations in argon gas flow rates for stirring. To track particle disintegration in the molten bath inside, intricate numerical processing was carried out with the use of mathematical models and to simulate the mixing process; turbulent multiphase computational fluid dynamics (CFD) models were combined with a user-defined function. The numerical findings highlight the connection between mixing time and gas blowing since the quantity of stirring plugs employed and the gas flow rates directly affect mixing effectiveness. The amount of particles to be injected and their total injection time were validated using industrial measurement; an average difference of 9.9% was achieved. In order to establish the need for an exceptionally high flow rate and inevitably reduce resource waste, extreme charging of flow rates for gas stirring were compared to lesser gas flow rates in both dual- and single-plug ladles. The results show that a single-plug ladle with a flow rate of 0.85 m3/min and a dual-plug ladle with a total flow rate of 1.13 m3/min have the same mixing time of 5.6 min, which was the shortest among all scenarios. 

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2. Reduction in sample injection bias using pressure gradients generated on chip

   https://doi.org/10.1002/elps.202000299  

   Liu, Yukari; Xia, Ling; Dutta, Debashis (February 2021, ELECTROPHORESIS)

   Abstract Sample injection in microchip‐based capillary zone electrophoresis (CZE) frequently rely on the use of electric fields which can introduce differences in the injected volume for the various analytes depending on their electrophoretic mobilities and molecular diffusivities. While such injection biases may be minimized by employing hydrodynamic flows during the injection process, this approach typically requires excellent dynamic control over the pressure gradients applied within a microfluidic network. The current article describes a microchip device that offers this needed control by generating pressure gradients on‐chip via electrokinetic means to minimize the dead volume in the system. In order to realize the desired pressure‐generation capability, an electric field was applied across two channel segments of different depths to produce a mismatch in the electroosmotic flow rate at their junction. The resulting pressure‐driven flow was then utilized to introduce sample zones into a CZE channel with minimal injection bias. The reported injection strategy allowed the introduction of narrow sample plugs with spatial standard deviations down to about 45 μm. This injection technique was later integrated to a capillary zone electrophoresis process for analyzing amino acid samples yielding separation resolutions of about 4–6 for the analyte peaks in a 3 cm long analysis channel. 

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3. VOLUMETRIC FLOW MEASUREMENT INSIDE A WATER LADLE MODEL WITH SHAKE-THE-BOX SYSTEM

   https://doi.org/10.1615/TFEC2022.tfs.040802  

   Guo, X; Liu, Y; Zhou, C (July 2022, Thermal and Fluids Engineering Summer Conference)

   The ladle furnace plays a critical role in the secondary steelmaking stage, where many processes take place in the ladle such as steel property and temperature homogenization, inclusion removal, degassing, and desulfurization. Although many research has been conducted to study these aspects, due to the complicated heat and mass transfer process inside the ladle, many details about the physical process are still not quite clear. For example, the efficacy of plug/injector designs in turbulent mixing of molten steel were not fully understood. Due to its complex three dimensional flow phenomena inside the ladle, previous two dimensional flow measurement of water ladle models provided little insight into understanding the three dimensional flow phenomenon of turbulent mixing. Therefore, to achieve a better understanding on the efficacy of plug/injector designs in turbulent mixing, we implemented an advanced volumetric flow measurement instrument of Shake-the-Box system to measure the three-dimensional flow field inside a water ladle model. Totally, three different plug/injector designs were tested under two different flow rates (8 LPM and 11.5 LPM) of gas injection within a volumetric flow measurement region of 4.8 cm × 4.8 cm × 2.4 cm. The flow measurement results suggest the double slits injector produces the highest turbulence kinetic energy comparing the three injectors. 

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4. Flow topology changes with bubbly flow around a circular cylinder

   https://doi.org/10.1016/j.ijmultiphaseflow.2024.104917  

   Thacher, Eric; Van_Ruymbeke, Bruno; Gabillet, Céline; Jacques, Nicolas; Mäkiharju, Simo A (September 2024, International Journal of Multiphase Flow)

   Vortex induced vibration (VIV) experienced during flow past a cylinder can reduce equipment performance and in some cases lead to failure. Previous studies have shown that the injection of bubbles in the flow over a cylinder typically leads to a monotonic increase in shedding frequency with void fraction, however, a satisfactory explanation for this phenomenon has not been proposed. Unexplained scatter in the data exists, including that the increase in shedding frequency is not universal. More research is needed to characterize the influence of bubbles on the wake structure, and subsequent shift in shedding frequency. To this aim, the effect of bubbles on the structure of the wake and VIV was examined over two values of Reynolds number, 𝑅𝑒𝐷 = 100, 000 and 160,000. Time-resolved particle image velocimetry (TR-PIV), proper orthogonal decomposition (POD) and spectral proper orthogonal decomposition (SPOD) of the wake structures, vibration of the cylinder, and bubble image velocimetry (BIV) were used to assess the flow topology changes under the influence of gas injection. Using SPOD/POD analysis in the near wake, it was found that the primary Karman shedding frequency decreased with the injection of gas, from a Strouhal number of St = 0.2 to St = 0.17−0.18; the width of the spectral peak was found to increase with void fraction. Notably, the vibration of the cylinder at the primary Karman shedding frequency was suppressed following the injection of gas, even at spanwiseaveraged volumetric qualities below 0.01%. This suppression occurred regardless of if gas was concentrated locally near the centerline of the channel, or along the span. BIV data suggests that gas accumulation in the near wake, driven by the high velocity vertical motion of gas, serves to uncouple the cylinder motion from the formation of the vortex street downstream while promoting faster wake recovery. 

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5. Monitoring and Characterization of Milk Fouling on Stainless Steel Using a High-Pressure High-Temperature Quartz Crystal Microbalance with Dissipation

   https://doi.org/10.1021/acs.langmuir.2c00419  

   Huellemeier, Holly A.; Eren, Necla M.; Payne, Taylor D.; Schultz, Zachary D.; Heldman, Dennis R. (October 2022, Langmuir)

   Fouling at interfaces deteriorates the efficiency and hygiene of processes within numerous industrial sectors, including the oil and gas, biomedical device, and food industries. In the food industry, the fouling of a complex food matrix to a heated stainless steel surface reduces production efficiency by increasing heating resistance, pumping requirements, and the frequency of cleaning operations. In this work, quartz crystal microbalance with dissipation (QCM-D) was used to study the interface formed by the fouling of milk on a stainless steel surface at different flow rates and protein concentrations at high temperatures (135 °C). Subsequently, the QCM-D response was recorded during the cleaning of the foulant. Two phases of fouling were identified. During phase-1, the fouling rate was dependent on the flow rate, while the fouling rate during phase-2 was dependent on the flow rate and protein concentration. During cleaning, foulants deposited at the higher flow rate swelled more than those deposited at the lower flow rate. The composition of the fouling deposits consisted of both protein and mineral species. Two crystalline phases of calcium phosphate, β-tricalcium phosphate and hydroxyapatite, were identified at both flow rates. Stratification in topography was observed across the surface of the QCM-D sensor with a brittle and cracked structure for deposits formed at 0.2 mL/min and a smooth and close-packed structure for deposits formed at 0.1 mL/min. These stratifications in the composition and topography were correlated to differences in the reaction time and flow dynamics at different flow rates. This high-temperature application of QCM-D to complex food systems illuminates the initial interaction between proteins and minerals and a stainless steel surface, which might otherwise be undetectable in low-temperature applications of QCM-D or at larger bench and industrial scales. The methods and results presented here have implications for optimizing processing scenarios that limit fouling formation while also enhancing removal during cleaning. 

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