Liquid phase exfoliation(LPE)process for graphene production is usually carried out in stirred tank reactor and the interactions between the solvent and the graphite particles are important as to improve the productio...
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Liquid phase exfoliation(LPE)process for graphene production is usually carried out in stirred tank reactor and the interactions between the solvent and the graphite particles are important as to improve the production *** this paper,these interactions were revealed by computational fluid dynamics–discrete element method(CFD-DEM)*** on simulation results,both liquid phase flow hydrodynamics and particle motion behavior have been analyzed,which gave the general information of the multiphase flow behavior inside the stirred tank reactor as to graphene *** calculating the threshold at the beginning of graphite exfoliation process,the shear force from the slip velocity was determined as the active *** results can support the optimization of the graphene production process.
Internally Circulating fluidized Bed (ICFB) reactors stand out as efficient technology in fluidized bed applications, featuring internal solid particle circulation that has garnered attention across various industries...
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Internally Circulating fluidized Bed (ICFB) reactors stand out as efficient technology in fluidized bed applications, featuring internal solid particle circulation that has garnered attention across various industries. This study employs computational fluid dynamics (CFD) simulation to investigate the impact of operating parameters on the hydrodynamics of an ICFB reactor using gamma-alumina (gamma-Al2O3) as a bed material. The gas-solid flow regime in the riser section is identified as a circulating turbulent fluidized bed (CTFB), contrasting with the downer section, which exhibits bubbling bed fluidization. Examining mechanisms governing solid circulation leads to the design of a pseudo-2D cold-flow ICFB unit with a reactor diameter ratio between riser and downer ranging from 2:1 to 1:2. It was found that, with a reactor diameter ratio of 1:2, solid volume fraction profiles in the axial and radial directions become denser and more uniform throughout the riser, while the downer section exhibits uniform distribution along both axial and radial directions. The dominant role of turbulent granular temperature in oscillations within the ICFB system is observed. This suggests the formation of gas bubbles and solid accumulation as the primary flow configurations, illustrating system mixing and defining hydrodynamics for both solid particles and gas phases. Consequently, this study advances our understanding of ICFB reactor dynamics and offers valuable insights for optimizing reactor design.
The heavy water reactor concept Teplator is a pressure channel type reactor with independent systems for the primary coolant and the moderator. The present study analyses the low-pressure moderator cooling system of T...
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The heavy water reactor concept Teplator is a pressure channel type reactor with independent systems for the primary coolant and the moderator. The present study analyses the low-pressure moderator cooling system of Teplator during full-power operation. The moderator is heated from neutron thermalization, gamma rays absorption, fission product decay, and decay of activation products. Additionally, heat transfer from the coolant channels has to be taken in the analyses of the moderator cooling system. Preliminary thermal-hydraulic analyses of the cooling system are supplemented by computational fluid dynamics (CFD) simulations of heat and fluid flow in the moderator's vessel, emphasizing flow-type regimes. Results from CFD simulations showed that the buoyancy-dominated flow (case MF-22) resulted in a higher thermal stratification and high moderator temperature close to the upper plate of the moderator vessel. The inertia-dominated flow regime MF-90 resulted in good mixing of the moderator and a low thermal stratification in the vessel. Finally, the midmass flow rate regime MF-45 was identified as a transitional region from a buoyancy-dominated to a mix-type regime.
This article is an examination of computational fluid dynamics in the field of otolaryngology, specifically rhinology. The historical development and subsequent application of computational fluid dynamics continues to...
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This article is an examination of computational fluid dynamics in the field of otolaryngology, specifically rhinology. The historical development and subsequent application of computational fluid dynamics continues to enhance our understanding of various sinonasal conditions and surgical planning in the field today. This article aims to provide a description of computational fluid dynamics, the methods for its application, and the clinical relevance of its results. Consideration of recent research and data in computational fluid dynamics demonstrates its use in nonhistological disease pathology exploration, accompanied by a large potential for surgical guidance applications. Additionally, this article defines in lay terms the variables analyzed in the computationalfluid dynamic process, including velocity, wall shear stress, area, resistance, and heat flux.
The present study investigates the scour phenomenon around different abutment geometries (such as vertical wall, 45 wing wall, and semi -circular abutments) under combined wave -current flows. A computationalfluid Dy...
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The present study investigates the scour phenomenon around different abutment geometries (such as vertical wall, 45 wing wall, and semi -circular abutments) under combined wave -current flows. A computational fluid dynamics (CFD) three-dimensional model is developed to simulate the scour mechanism under combined wavecurrent flows accurately. The developed advanced model integrates the Level Set method (LSM) to represent both bed surface and free surface elevation realistically. The numerical CFD model undergoes validation for studying the temporal abutment scour under various flow conditions, including steady currents and the combined waves and current. Further, the influence of the Keulegan-Carpenter (KC) number and combined wave -current parameter (Ucw) on the normalized equilibrium scour depth (S/L) of various abutment geometries is analyzed. The results suggest that the maximum equilibrium scour depth is observed around the vertical wall abutment. Nevertheless, the semi -circular abutment experiences the least scour depth when the waves are superimposed on the current. The results demonstrate that an increase in the Ucw parameter, as well as the KC number, increases the S/L values around abutments.
A phase change material (PCM) is an organic (or inorganic) chemical that may store and release thermal energy in latent form as it changes physical states. This investigation aims to see how phase transition materials...
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A phase change material (PCM) is an organic (or inorganic) chemical that may store and release thermal energy in latent form as it changes physical states. This investigation aims to see how phase transition materials influence the thermal efficiency of the solar dryer. For the performance analysis, three PCMs were used: paraffin wax, lauric acid, and palmitic acid. As drying material, 5 mm thick potato slices were employed. According to the computational results, the total input thermal energy for the dryer for paraffin wax, lauric acid, and palmitic acid was about 17.36 MJ, 18.46 MJ, and 17.76 MJ, respectively, for 2 kg drying mass. When paraffin wax, lauric acid, and palmitic acid were utilized, the overall efficiency of the dryer increased by about 87%, 40.2%, and 12.4%, respectively, compared to the conventional dryer. By comparing the results of simulations and predictions, it is concluded that paraffin wax is the best -performing PCM for solar dryers as the energy storage material.
computational fluid dynamics (CFD) plays a prominent role in the design and development of solar air heaters. The previous investigations have lagged in using a radiation model for the solar heat input;instead, most o...
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computational fluid dynamics (CFD) plays a prominent role in the design and development of solar air heaters. The previous investigations have lagged in using a radiation model for the solar heat input;instead, most of the researchers simulated a constant heat flux model. Moreover, an extensive study on the geometrical and boundary conditions like confinement and transition length, suction, and blowing effects has not been studied. The present investigation deals with the aforementioned effects on the flow and heat transfer characteristics of the SAH channel, which is designed for residential space heating. The finite volume-based solver Ansys Fluent is used for finding the field variables. The confinement height is varied from 25 to 150 mm, and the transition length is varied from 250 to 1000 mm. The suction and blowing effect is investigated by changing the flow direction across the channel. Even though the temperature rise is less significant with respect to confinement height and transition length, the effective efficiency increases with decreasing channel height and increasing transition length. In general, blowing of air across the channel gives better performance than suction. When comparing them, the influence is less in temperature rise and more in pressure drop for the channel height of 25 mm, whereas the channel height of 150 mm has better influence in temperature rise and less influence in pressure drop.
This work investigated the partition walls or baffles' effects on hydraulic parameters and water retention time in a reservoir. According to this aim, the water system was equipped with remote sensing (RS), networ...
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This work investigated the partition walls or baffles' effects on hydraulic parameters and water retention time in a reservoir. According to this aim, the water system was equipped with remote sensing (RS), networked sensors, advanced modems, and data loggers. The study showed how to control hydraulic parameters by the Internet of things and RS. The higher retention time led to the probability growth of rebar oxidation in concrete in the presence of chlorine and increased the possibility of water loss. This work also showed how to decrease the probability of water leakage in reservoirs. The computational fluid dynamics analysis results showed that the two baffles case led to the emergence of three eddy currents in the three zones created. The better fluid interpenetration caused the reduction in retention time. In the areas where the vortex was formed, the number of eddy currents decreased and the retention time increased. Regression analysis showed that the P value was 0.998 and 0.977 for the inlet flow and outlet flow for the reservoir, respectively (two baffles case perpendicular to the flow direction). The curve estimation showed that the power function had a suitable correlation on the scatter diagram and with the best curve fit.
Spraying is the most widely used method for pesticide application and the resulting spray drift has become a major concern. Reliable spray simulations can help to better understand this phenomenon and evaluate methods...
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Spraying is the most widely used method for pesticide application and the resulting spray drift has become a major concern. Reliable spray simulations can help to better understand this phenomenon and evaluate methods to prevent it. This paper proposes a methodology to set up a computational fluid dynamics simulation of sprays. A number of benchmark flows were studied to assess the accuracy of the proposed method. The simulation of a jet in a crossflow was able to capture counter-rotating vortex pairs and the predicted trajec-tory agreed with experimental data. A multiple-injector technique is then used to replicate the velocity distribution of sprays without modelling the liquid sheet breakup. Spray simulations were able to capture air entrainment and predicted a realistic droplet distri-bution pattern. The volume of droplets deposited on the collector lines in drift simulations was in good agreement with experimental data in the near field. As the droplets moved further downstream, however, a deviation between the simulation results and experi-mental data was observed. The drift simulation results indicated that in a wind speed of 2 m s-1, droplets of diameter < 75 mm are prone to drift.(c) 2023 IAgrE. Published by Elsevier Ltd. All rights reserved.
The Kentucky Re-Entry Universal Payload System (KRUPS) is a low-cost space capsule that has been designed to collect flight data. This work focuses on computational fluid dynamics (CFD) simulations of the flow around ...
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The Kentucky Re-Entry Universal Payload System (KRUPS) is a low-cost space capsule that has been designed to collect flight data. This work focuses on computational fluid dynamics (CFD) simulations of the flow around the capsule at various altitudes along the trajectory path during Earth re-entry. CFD simulations are performed at altitudes of 60 and 40 km by accounting for thermochemical nonequilibrium and surface catalycity using current state-of-the-art hypersonic approaches. The flowfield at all altitudes exhibits significant thermal and chemical nonequilibrium with vibrational temperature lagging the translational temperature in the forebody and exceeding the translational temperature in the wake. Inclusion of surface catalycity influences the heat flux on the surface and the flow temperature in the boundary layer. The number density profiles of nitric oxide molecules and spectral emission computations using the line-by-line radiative solver NEQAIR indicate that higher emissions would occur at an altitude of 60 km in comparison to emissions at 40 km, and spectral intensity would be higher along the stagnation line despite high densities of NO near the edges of the capsule, and that emissions in the 100-400 nm wavelength range are dominant.
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