scholarly journals Using CFD Simulations to Guide the Development of a New Spray Dryer Design

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 932
Author(s):  
Timothy A. G. Langrish ◽  
James Harrington ◽  
Xing Huang ◽  
Chao Zhong
Keyword(s):  
Deposition Process ◽  
Operating Conditions ◽  
Feed Concentration ◽  
Cfd Simulations ◽  
Physical Experiments ◽  
Solids Concentration ◽  
Computational Fluid Dynamics Cfd ◽  
Higher Temperature ◽  
Drying System ◽  
Drying Chamber

A new spray-drying system has been designed to overcome the limitations caused by existing designs. A key feature of the approach has been the systematic use of Computational Fluid Dynamics (CFD) to guide innovation in the design process. An example of an innovation is the development of a box-shaped transitional feature between the bottom of the main drying chamber and the entrance to the secondary chamber. In physical experiments, the box design performed better in all three representative operating conditions, including the current conditions, a higher feed solids concentration (30% solids rather than 8.8%), and a higher inlet drying temperature (230 °C rather than 170 °C). The current conditions showed a 3% increase in yield (solids recovery) while the 30% feed condition improved the yield by 7.5%, and the higher temperature test increased the yield by 13.5%. Statistical analysis showed that there were significant reductions in the wall flux at the high solids feed concentration. The observed deposition in the box was primarily from the predicted particle impacts by an inertial deposition process on the base of the box, which underwent little degradation due to lower temperatures. There is therefore evidence that the box design is a better design alternative under all operating conditions compared with other traditional designs.

CFD Simulations of the Cold Neutron Source at the OPAL Reactor

2020 ◽  
Author(s):  
James L Spedding ◽  
Mark Ho ◽  
Weijian Lu
Keyword(s):  
Neutron Source ◽  
Cold Neutron ◽  
Operating Conditions ◽  
Convergence Time ◽  
Cfd Model ◽  
Cfd Simulations ◽  
Cold Neutron Source ◽  
Order Of Magnitude ◽  
Computational Fluid Dynamics Cfd ◽  
Polyhedral Mesh

Abstract The Open Pool Australian Light-water (OPAL) reactor Cold Neutron Source (CNS) is a 20 L liquid deuterium thermosiphon system which has performed consistently but will require replacement in the future. The CNS deuterium exploits neutronic heating to passively drive the thermosiphon loop and is cryogenically cooled by forced convective helium flow via a heat exchanger. In this study, a detailed computational fluid dynamics (CFD) model of the complete thermosiphon system was developed for simulation. Unlike previous studies, the simulation employed a novel polyhedral mesh technique. Results demonstrated that the polyhedral technique reduced simulation computational requirements and convergence time by an order of magnitude while predicting thermosiphon performance to within 1% accuracy when compared with prototype experiments. The simulation model was extrapolated to OPAL operating conditions and confirmed the versatility of the CFD model as an engineering design and preventative maintenance tool. Finally, simulations were performed on a proposed second-generation CNS design that increases the CNS moderator deuterium volume by 5 L, and results confirmed that the geometry maintains the thermosiphon deuterium in the liquid state and satisfies the CNS design criteria.

Impact of Blockage on the Hydrodynamic Performance of Oscillating-Foils Hydrokinetic Turbines

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Etienne Gauthier ◽  
Thomas Kinsey ◽  
Guy Dumas
Keyword(s):  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Blockage Ratio ◽  
Cfd Simulations ◽  
Hydrokinetic Turbines ◽  
Marine Energy ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact ◽  
Do So ◽  
Oscillating Foils

This paper describes a study of the impact of confinement on the hydrodynamic performance of oscillating-foils hydrokinetic turbines (OFHT). This work aims to contribute to the development of standards applying to marine energy converters. These blockage effects have indeed to be taken into account when comparing measurements obtained in flumes, towing tanks, and natural sites. This paper provides appropriate correction formula to do so for OFHT based on computational fluid dynamics (CFD) simulations performed at a Reynolds Number Re = 3 × 106 for reduced frequencies between f* = 0.08 and f* = 0.22 considering area-based blockage ratios ranging from ε = 0.2% to 60%. The need to discriminate between the vertical and horizontal confinement and the impact of the foil position in the channel are also investigated and are shown to be of second-order as compared to the overall blockage level. As expected, it is confirmed that the power extracted by the OFHT increases with the blockage level. It is further observed that for blockage ratio of less than ε = 40%, the power extracted scales linearly with ε. The approach proposed to correlate the performance of the OFHT in different blockage conditions uses the correction proposed by Barnsley and Wellicome and assumes a linear relation between the power extracted and the blockage. This technique is shown to be accurate for most of the practical operating conditions for blockage ratios up to 50%.

Analysis of Turbofan Performance Under Total Pressure Distortion at Various Operating Points

2015 ◽  
Author(s):  
David B. Weston ◽  
Steven E. Gorrell ◽  
Matthew L. Marshall ◽  
Carol V. Wallis
Keyword(s):  
Total Pressure ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Cfd Simulations ◽  
Blade Loading ◽  
Distortion Analysis ◽  
Work Input ◽  
Total Temperature ◽  
Computational Fluid Dynamics Cfd ◽  
Operating Points

Inlet distortion is an important consideration in fan performance. The focus of this paper is a series of high-fidelity time accurate Computational Fluid Dynamics (CFD) simulations of a multistage fan at choke, design, and near stall operating conditions. These investigate distortion transfer and generation as well as the underlying flow physics of these phenomena under different operating conditions. The simulations are performed on the full annulus of a 3 stage fan and are analyzed. The code used to carry out these simulations is a modified version of OVERFLOW 2.2. The inlet is specified as a 1/rev total pressure distortion. Analysis includes the phase and amplitude of total temperature and pressure distortion through each stage of the fan and blade loading. The total pressure distortion does not change in severity through the fan, but the peak pressure distortion rotates by as much as 45° at the near stall point. This is due to a variation in the work input around the blades of the rotor. This variation is also responsible for the generation of total temperature distortion in the fan. The rotation of the total temperature distortion becomes more pronounced as the fan approaches stall, and the total temperature distortion levels increase. The amount of work performed by a single blade can vary by as much as 25% in the first stage at near stall. The variation in work becomes more pronounced as the fan approaches stall. The passage shock in the rotor blades moves nearly 20% of the blade chord in both the peak efficiency and near stall cases.

scholarly journals Application of Computational Fluid Dynamics (CFD) in the Deposition Process and Printability Assessment of 3D Printing Using Rice Paste

Processes ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 68
Author(s):  
Timilehin Martins Oyinloye ◽  
Won Byong Yoon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
3D Printing ◽  
Deposition Process ◽  
Operating Conditions ◽  
Nozzle Diameter ◽  
Cfd Analysis ◽  
Flow Properties ◽  
Swell Ratio ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) was utilized to investigate the deposition process and printability of rice paste. The rheological and preliminary printing studies showed that paste formed from rice to water ratio (100:80) is suitable for 3D printing (3DP). Controlling the ambient temperature at C also contributed to improving the printed sample’s structural stability. The viscoelastic simulation indicated that the nozzle diameter influenced the flow properties of the printed material. As the nozzle diameter decreased (1.2 mm to 0.8 mm), the die swell ratio increased (13.7 to 15.15%). The rise in the swell ratio was a result of the increasing pressure gradient at the nozzle exit (5.48 × 106 Pa to 1.53 × 107 Pa). The additive simulation showed that the nozzle diameter affected both the residual stress and overall deformation of the sample. CFD analysis, therefore, demonstrates a significant advantage in optimizing the operating conditions for printing rice paste.

scholarly journals Intensification of liquid mixing and local turbulence using a fractal injector with staggered conformation

2021 ◽  
Author(s):  
Shuxian Jiang ◽  
Marc-Olivier Coppens ◽  
Jia-Jun WANG
Keyword(s):  
Flow Field ◽  
Operating Conditions ◽  
Cfd Simulations ◽  
Mixing Performance ◽  
Double Ring ◽  
Spatially Distributed ◽  
Field Uniformity ◽  
Reaction Region ◽  
Dissipation Model ◽  
Computational Fluid Dynamics Cfd

Two self-similar, tree-like injectors of the same fractal dimension are compared, demonstrating that other geometric parameters besides dimension play a crucial role in determining mixing performance. In one injector, when viewed from the top, the conformation of branches is eclipsed; in the other one, it is staggered. The flow field and the fractal injector induced mixing performance are investigated through computational fluid dynamics (CFD) simulations. The finite rate/eddy dissipation model (FR/EDM) is modified for fast liquid-phase reactions involving local micromixing. Under the same operating conditions, flow field uniformity and micromixing are improved when a staggered fractal injector is used. This is because of enhanced jet entrainment and local turbulence around the spatially distributed nozzles. Compared with a traditional double-ring sparger, a larger reaction region volume and lower micromixing time are obtained with fractal injectors. Local turbulence around the spatially distributed nozzles in fractal injectors improves reaction efficiency.

Flow Analysis and Assessment of Loss Models in the Symmetric Volute of a Turbo-Blower

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Semi Kim ◽  
Junyoung Park ◽  
Bumseok Choi ◽  
Jehyun Baek
Keyword(s):  
Cfd Simulation ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Cfd Simulations ◽  
Turbo Blower ◽  
Mass Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Loss Coefficients ◽  
Simulated Flow

The objectives of the present study were to investigate the flow structure and assess the accuracy of loss correlations in the symmetric volute of a turbo-blower using 3D steady flow analysis methods. To accurately model the flow field in the volute, an impeller with a single blade, a diffuser with 13 vanes, and a volute were used as the calculation domains for the computational fluid dynamics (CFD) simulations. Numerical results were validated by comparison with experimental results for the performance of a turbo-blower operated under three operating conditions: high (0.38 kg/s), normal (0.3 kg/s), and low (0.23 kg/s) mass flow rates. The accuracy of the loss correlation sets reported in four previous studies was compared with the CFD simulation predictions. These comparisons showed that the correlation sets did not accurately represent the total pressure loss in the symmetric volute of a turbo-blower, and a modified correlation set that included adjustments for the loss coefficients was proposed. Detailed investigations of the simulated flow fields were compared to understand the flow characteristics in the volute under the designed operating conditions.

scholarly journals Development of a Low-Friction Radial Shaft Seal: Using CFD Simulations to Optimise the Microstructured Sealing Lip

Lubricants ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 41
Author(s):  
Dennis Keller ◽  
Georg Jacobs ◽  
Stephan Neumann
Keyword(s):  
Operating Conditions ◽  
Friction Reduction ◽  
Navier Stokes ◽  
Performance Limits ◽  
Cfd Simulations ◽  
Navier Stokes Equation ◽  
Simulation Based ◽  
Drive Trains ◽  
Computational Fluid Dynamics Cfd ◽  
Shaft Seals

The sealing of shaft interfaces in machine housings against oil leakage is commonly realized by radial shaft seals, hence they are used millions of times in technical systems. However, with increasing speed they cause significant friction losses, which reduce the efficiency of the system significantly. In addition, the prevailing trend towards higher speed levels in electrified drive trains is already pushing sealing technology to its performance limits. Therefore, friction reduction offers a chance to extend the current performance limits and increase efficiency within existing applications. In this paper, a methodology for friction reduction is proposed, which is based on microstructuring and surface treatment of the seal sliding surface. Since experimental structural design is linked to high costs and time, a simulation-based method is proposed. Computational Fluid Dynamics (CFD) simulations are performed to analyze the influence of the structural geometry on local fluid flow. It is shown that for increasing sliding speeds, the analysis and the subsequent optimization of deterministic microstructures require the numerical solution of the complete Navier–Stokes equation in order to take inertial effects into account. Based on these results, an optimal geometric shape for the microstructure is found depending on the operating conditions.

Prediction of Deposition Patterns in a Pilot-Scale Spray Dryer Using Computational Fluid Dynamics (CFD) Simulations

2007 ◽  
Vol 2 (3) ◽  
Author(s):  
Kashinath Kota ◽  
Tim Langrish
Keyword(s):  
Fluid Dynamics ◽  
Flow Rate ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Spray Dryer ◽  
Air Flow Rate ◽  
Cfd Simulations ◽  
Deposition Fluxes ◽  
Deposition Patterns ◽  
Computational Fluid Dynamics Cfd

This paper presents the predictions of deposition patterns using CFD simulations based on transient-flow behaviour of a 1.6 m high, 0.8 m diameter, pilot-scale spray dryer, following from previous studies assessing the use of Computational Fluid Dynamics (CFD) simulations to predict the deposition on a plate in a simple box configuration. The predicted deposition fluxes here have been compared with experimental data for the deposition fluxes of skim milk, maltodextrin and water. The CFD simulation results suggested that the effect of transient air flows on the vertical patterns of deposition fluxes with distance up the dryer wall for no inlet air swirl is small. The CFD simulations underpredicted the experimental values of the deposition fluxes by approximately 50%, but the simulations predicted the same experimental trends when changing the main air flow rate through the dryer. The experimentally-measured deposition fluxes were 38%, on average, higher at a main air flow rate of 113 kg/h compared with those at a flow rate of 88 kg/h. The CFD simulations predicted an average increase in deposition flux of 26% at 113 kg/h compared with 88 kg/h, so the trends with this change in operating conditions have been predicted well by the CFD simulations. One-way particle coupling has therefore shown correct trends in the deposition fluxes with respect to both positions in the dryer and different operating conditions, and such one-way coupling is several orders of magnitude faster than the more rigorous two-way coupling.

scholarly journals Using CFD to Evaluate Natural Ventilation through a 3D Parametric Modeling Approach

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2197
Author(s):  
Nayara Rodrigues Marques Sakiyama ◽  
Jurgen Frick ◽  
Timea Bejat ◽  
Harald Garrecht
Keyword(s):  
Natural Ventilation ◽  
Parametric Modeling ◽  
Cfd Simulations ◽  
3D Design ◽  
Post Process ◽  
Test House ◽  
Model Set ◽  
Computational Fluid Dynamics Cfd ◽  
Set Up ◽  
Passive Strategy

Predicting building air change rates is a challenge for designers seeking to deal with natural ventilation, a more and more popular passive strategy. Among the methods available for this task, computational fluid dynamics (CFD) appears the most compelling, in ascending use. However, CFD simulations require a range of settings and skills that inhibit its wide application. With the primary goal of providing a pragmatic CFD application to promote wind-driven ventilation assessments at the design phase, this paper presents a study that investigates natural ventilation integrating 3D parametric modeling and CFD. From pre- to post-processing, the workflow addresses all simulation steps: geometry and weather definition, including incident wind directions, a model set up, control, results’ edition, and visualization. Both indoor air velocities and air change rates (ACH) were calculated within the procedure, which used a test house and air measurements as a reference. The study explores alternatives in the 3D design platform’s frame to display and compute ACH and parametrically generate surfaces where air velocities are computed. The paper also discusses the effectiveness of the reference building’s natural ventilation by analyzing the CFD outputs. The proposed approach assists the practical use of CFD by designers, providing detailed information about the numerical model, as well as enabling the means to generate the cases, visualize, and post-process the results.

scholarly journals Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract

2021 ◽  
Vol 11 (7) ◽  
pp. 2961
Author(s):  
Nikola Čajová Kantová ◽  
Alexander Čaja ◽  
Marek Patsch ◽  
Michal Holubčík ◽  
Peter Ďurčanský
Keyword(s):  
Particulate Matter ◽  
Flue Gas ◽  
Gas Flow ◽  
Negative Impact ◽  
Combustion Process ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Computational Fluid Dynamics Cfd ◽  
Particle Imaging ◽  
Combustion Of Solid Fuels

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.

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