scholarly journals CFD simulations of rotary BOF slag carbonation kiln reactor with cyclone flow

2019 ◽  
Vol 234 (1) ◽  
pp. 37-45
Author(s):  
Tong-Bou Chang ◽  
Cho-Yu Lee ◽  
Ming-Sheng Ko ◽  
Chin-Fong Lim
Keyword(s):  
Residence Time ◽  
Rotary Kiln ◽  
Basic Oxygen Furnace ◽  
Cfd Simulations ◽  
Carbonation Reaction ◽  
Carbonation Process ◽  
Taguchi Experimental Method ◽  
Bof Slag ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Rotary kiln reactors play an important role in improving the mechanical properties and usability of basic oxygen furnace slag through a carbonation process. The performance of such reactors is critically dependent on the residence time of the CO2 gas used to promote the carbonation reaction. Accordingly, the present study proposes a rotary kiln reactor in which the residence time is increased by arranging the inlet and outlet pipes obliquely to the reactor centerline; thereby producing a cyclone flow structure within the reactor tube. The optimal geometry parameters and rotational speed of the kiln are determined using the robust Taguchi experimental method. The CO2 residence time in the optimized kiln is then evaluated by means of computational fluid dynamics simulations. It is shown that the residence time increases from 63.587 s in a standard (non-cyclone-flow) rotary kiln to 105.815 s in the optimized rotary kiln; corresponding to a performance improvement of 66.4%.

Comparison of Aneurismal Hemodynamics Between 4-D Accelerated Phase-Contrast MR Angiography and Computational Fluid Dynamics Simulations: Initial Experience in a Canine Aneurysm Model

2010 ◽  
Author(s):  
Jingfeng Jiang ◽  
Kevin Johnson ◽  
Kristian Valen-Sendstad ◽  
Kent-Andre Mardal ◽  
Dan Consigny ◽  
...  
Keyword(s):  
Blood Flow ◽  
Therapeutic Interventions ◽  
Cfd Simulations ◽  
Stent Deployment ◽  
Blood Flow Imaging ◽  
Flow Information ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Realistic Geometries ◽  
Aneurysm Model

The etiology and progression of intracranial aneurysms (IAs) are closely associated with complex patterns of disturbed blood flow. [1] Consequently, blood flow imaging [2] and CFD simulations in realistic geometries [3, 4] are of clinical interests because flow information obtained by such techniques can provide insight not only into the development and progression of IAs but also into their responses to therapeutic interventions (e.g. coil embolization and stent deployment).

scholarly journals CFD Simulations of Splash Losses of a Gearbox

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Carlo Gorla ◽  
Franco Concli ◽  
Karsten Stahl ◽  
Bernd-Robert Höhn ◽  
Michaelis Klaus ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Experimental Results ◽  
Operating Parameters ◽  
Main Concern ◽  
Design Phase ◽  
Power Losses ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Efficiency is becoming a main concern in the design of power transmissions. It is therefore important, especially during the design phase, to have appropriate models to predict the power losses. For this reason, CFD (computational fluid dynamics) simulations were performed in order to understand the influence of geometrical and operating parameters on the losses in power transmissions. The results of the model were validated with experimental results.

Design of Fire Ventilation System for an Underground Car Park by CFD Simulations

2019 ◽  
Vol 887 ◽  
pp. 459-466
Author(s):  
Miroslava Kmecová ◽  
Peter Buday ◽  
Jozef Vojtaššák ◽  
Michal Krajčík
Keyword(s):  
Fluid Flow ◽  
Ventilation System ◽  
Computer Software ◽  
Contamination Level ◽  
Cfd Simulations ◽  
Car Park ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Fluid Behaviour ◽  
Two Alternatives

The aim of this study is to design a fire ventilation system with impulse jet fans for an underground car park. During the planning, it is necessary to consider all aspects of fluid behaviour however, there is a number of parameters that can affect the flow of smoke that need to be considered. There is a good chance of miscalculations when computing the overall fluid flow using conventional plain calculations. To avoid mistakes, visualize the fluid flow and also to directly compare the different design variants it can be practical to use computer software, specifically CFD (Computational Fluid Dynamics) simulations. By CFD it is possible to better analyse and keep control of the flow of fluid, heat transfer and other related phenomena. It also helps predict the contamination level of Carbon Monoxide, heat and smoke intensity and distribution. In this study CFD simulations were used to design, test and compare two alternatives of fire ventilation system. The two alternatives differed from each other in the location of the impulse jet fans and exhaust ventilation shafts, and in the ventilation intensity (10-times per hour in the first alternative and 15-times per hour in the second alternative). The results have shown that the first alternative is not suitable as the car park was not sufficiently ventilated after 1500 seconds after the simulation had begun, whereas in the second alternative the smoke was almost completely exhausted and the visibility was significantly improved. The simulation results emphasize the important effect of design and location of the different elements on the functionality and efficiency of a fire protection system.

scholarly journals Time-Dependent Strength Behavior, Expansion, Microstructural Properties, and Environmental Impact of Basic Oxygen Furnace Slag-Treated Marine-Dredged Clay in South Korea

2021 ◽  
Vol 13 (9) ◽  
pp. 5026
Author(s):  
Gyeong-o Kang ◽  
Jung-goo Kang ◽  
Jin-young Kim ◽  
Young-sang Kim
Keyword(s):  
Particle Size ◽  
Environmental Impact ◽  
South Korea ◽  
Mechanical Characteristics ◽  
Basic Oxygen Furnace ◽  
Microstructural Properties ◽  
Compression Tests ◽  
Basic Oxygen ◽  
Strength Behavior ◽  
Bof Slag

The aim of this study was to investigate the mechanical characteristics, microstructural properties, and environmental impact of basic oxygen furnace (BOF) slag-treated clay in South Korea. Mechanical characteristics were determined via the expansion, vane shear, and unconfined compression tests according to various curing times. Scanning electron microscopy was conducted to analyze microstructural properties. Furthermore, environmental impacts were evaluated by the leaching test and pH measurements. According to the results, at the early curing stage (within 15 h), the free lime (F-CaO) content of the BOF slag is a significant factor for developing the strength of the adopted sample. However, the particle size of the BOF slag influences the increase in the strength at subsequent curing times. It was inferred that the strength behavior of the sample exhibits three phases depending on various incremental strength ratios. The expansion magnitude of the adopted samples is influenced by the F-CaO content and also the particle size of the BOF slag. Regarding the microstructural properties, the presence of reticulation structures in the amorphous gels with intergrowths of rod-like ettringite formation was verified inside the sample. Finally, the pH values and heavy metal leachates of the samples were determined within the compatible ranges of the threshold effect levels in the marine sediments of the marine environment standard of the Republic of Korea.

scholarly journals Component Modification of Basic Oxygen Furnace Slag with C4AF as Target Mineral and Application

2021 ◽  
Vol 13 (12) ◽  
pp. 6536
Author(s):  
Yanrong Zhao ◽  
Pengliang Sun ◽  
Ping Chen ◽  
Xiaomin Guan ◽  
Yuanhao Wang ◽  
...  
Keyword(s):  
Intermediate Phase ◽  
Raw Materials ◽  
Activity Index ◽  
Basic Oxygen Furnace ◽  
Hydration Products ◽  
Basic Oxygen ◽  
Bof Slag ◽  
Mineral Compositions ◽  
Slag Component ◽  
Basic Oxygen Furnace Slag

In this paper, a new method of basic oxygen furnace (BOF) slag component modification with a regulator was studied. The main mineral was designed as C4AF, C2S and C3S in modified BOF slag, and the batching method, mineral compositions, hydration rate, activation index and capability of resisting sulfate corrode also were studied. XRD, BEI and EDS were used to characterize the mineral formation, and SEM was used to study the morphology of hydration products. The results show that most inert phase in BOF slag can be converted into active minerals of C4AF and C2S through reasonable batching calculation and the amount of regulating agent. The formation of C4AF and C2S in modified BOF slag is better, and a small amount of MgO is embedded in the white intermediate phase, but C3S is not detected. With the increase in the CaO/SiO2 ratio in raw materials, the CaO/SiO2 ratio of calcium silicate minerals in modified BOF slag increases, the contents of f-CaO are less than 1.0%, and the activity index improves. Compared with the BOF slag, the activity index and exothermic rate of modified BOF slag improved obviously, and the activity index of 90 days is close to 100%. With the increase in modified BOF slag B cement, the flexural strength decrease; however, the capability of resisting sulfate corrode is improved due to the constant formation of a short rod-like shape ettringite in Na2SO4 solution and the improvement of the structure densification of the hydration products.

scholarly journals Aerodynamic analysis of uphill drafting in cycling

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
T. van Druenen ◽  
B. Blocken
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Scientific Literature ◽  
Sensitivity Analyses ◽  
Air Resistance ◽  
Wind Tunnel Measurements ◽  
Aerodynamic Effect ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

AbstractSome teams aiming for victory in a mountain stage in cycling take control in the uphill sections of the stage. While drafting, the team imposes a high speed at the front of the peloton defending their team leader from opponent’s attacks. Drafting is a well-known strategy on flat or descending sections and has been studied before in this context. However, there are no systematic and extensive studies in the scientific literature on the aerodynamic effect of uphill drafting. Some studies even suggested that for gradients above 7.2% the speeds drop to 17 km/h and the air resistance can be neglected. In this paper, uphill drafting is analyzed and quantified by means of drag reductions and power reductions obtained by computational fluid dynamics simulations validated with wind tunnel measurements. It is shown that even for gradients above 7.2%, drafting can yield substantial benefits. Drafting allows cyclists to save over 7% of power on a slope of 7.5% at a speed of 6 m/s. At a speed of 8 m/s, this reduction can exceed 16%. Sensitivity analyses indicate that significant power savings can be achieved, also with varying bicycle, cyclist, road and environmental characteristics.

scholarly journals Evaluation of Active Heat Sinks Design under Forced Convection—Effect of Geometric and Boundary Parameters

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2041
Author(s):  
Eva C. Silva ◽  
Álvaro M. Sampaio ◽  
António J. Pontes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Trapezoidal Shape ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This study shows the performance of heat sinks (HS) with different designs under forced convection, varying geometric and boundary parameters, via computational fluid dynamics simulations. Initially, a complete and detailed analysis of the thermal performance of various conventional HS designs was taken. Afterwards, HS designs were modified following some additive manufacturing approaches. The HS performance was compared by measuring their temperatures and pressure drop after 15 s. Smaller diameters/thicknesses and larger fins/pins spacing provided better results. For fins HS, the use of radial fins, with an inverted trapezoidal shape and with larger holes was advantageous. Regarding pins HS, the best option contemplated circular pins in combination with frontal holes in their structure. Additionally, lattice HS, only possible to be produced by additive manufacturing, was also studied. Lower temperatures were obtained with a hexagon unit cell. Lastly, a comparison between the best HS in each category showed a lower thermal resistance for lattice HS. Despite the increase of at least 38% in pressure drop, a consequence of its frontal area, the temperature was 26% and 56% lower when compared to conventional pins and fins HS, respectively, and 9% and 28% lower when compared to the best pins and best fins of this study.

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