Effect of the contact tank geometry on disinfection efficiency

2021 ◽  
Author(s):  
P. Bruno ◽  
G. Di Bella ◽  
M. De Marchis
Keyword(s):  
Tank Geometry

scholarly journals Thermal modeling of hydrogen storage by absorption in a magnesium hydrides tank

2014 ◽  
Vol 5 ◽  
pp. A21 ◽  
Author(s):  
Karim Lahmer ◽  
Rachid Bessaïh ◽  
Angel Scipioni ◽  
Mohammed El Ganaoui
Keyword(s):  
Hydrogen Absorption ◽  
Numerical Scheme ◽  
Computational Time ◽  
Governing Equations ◽  
Time Step ◽  
Kinetic Reaction ◽  
Fully Implicit ◽  
Temporal Profiles ◽  
Tank Geometry ◽  
Reaction Equations

This paper summarizes numerical results of hydrogen absorption simulated in an axisymmetric tank geometry containing magnesium hydride heated to 300 °C and at moderate storage pressure 1 MPa. The governing equations are solved with a fully implicit finite volume numerical scheme used by a commercial software FLUENT. The effect of the different kinetic reaction equations modeling hydrogen absorption was studied by the introduction of a specific subroutine at each time step in order to consider which one will provide results close to available experimental results. Spatial and temporal profiles of temperature and concentration in hydride bed are plotted. Results show that suitable method for our two-dimensional study is a CV-2D technique because it generates the smallest error especially during the beginning of the reaction. Also, its computational time is the shortest one compared to the other methods.

Evaluation of Storage Tank Floating Roofs for Stress and Stability Due to Earthquake Induced Liquid Sloshing

2007 ◽  
Author(s):  
Philip J. Cacciatore ◽  
Benjamin F. Hantz ◽  
L. Magnus Gustafsson
Keyword(s):  
Liquid Fuel ◽  
Theoretical Foundation ◽  
Liquid Sloshing ◽  
Storage Tanks ◽  
Analysis Method ◽  
Seismic Belt ◽  
Oil Storage ◽  
Fire Disaster ◽  
Work Done ◽  
Tank Geometry

Considerable interest has developed in the engineering community concerning the damage to the floating roof of oil storage tanks due to liquid sloshing from earthquake loading. Engineering groups in countries bordering the circum-Pacific seismic belt in particular are devoting extensive efforts to obtaining solutions capable of identifying vulnerable roof designs and developing modifications to improve strength. The recent efforts of the Japanese Fire Disaster and Management Authority (FDMA) as a result of 1995 Kobe and the 2003 Tokachi-Oki earthquakes are examples of recent work in this area. This paper focuses on efforts to analyze floating roof structures for stress and stability under typical earthquake velocity spectrums using advanced finite element methods. It employs ideas included in the Japanese FDMA studies, work done as part of the ASCE Committee on Gas and Liquid Fuel Lifelines, and some original methods developed at ExxonMobil. It has been applied to several tank designs and been submitted as a suitable advance analysis method to the Japanese FDMA. The paper provides both the theoretical foundation as well as an example covering typical tank geometry.

Mixing in Large Scale Tanks: Part I — Flow Modeling of Turbulent Mixing Jets

2004 ◽  
Author(s):  
Si Young Lee ◽  
Robert A. Dimenna ◽  
Richard A. Leishear ◽  
David B. Stefanko
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Liquid Level ◽  
Computational Results ◽  
Validation Data ◽  
Flow Measurements ◽  
Three Dimensional Representation ◽  
Lower Elevation ◽  
Tank Geometry

Flow evolution models were developed to evaluate the performance of the new advanced design mixer pump (ADMP) for sludge mixing and removal operations in one of the large-scale Savannah River Site (SRS) waste tanks, Tank 18. This paper is the first in a series of four that describe the computational model and its validation, the experiment facility and the flow measurements used to provide the validation data, the extension of the computational results to real tank conditions through the use of existing sludge suspension data, and finally, the sludge removal results from actual Tank 18 operations using the new ADMP. A computational fluid dynamics (CFD) approach was used to simulate the sludge removal operations. The models employed a three-dimensional representation of the tank with a two-equation turbulence model, since this approach was verified by both test and literature data. The discharge of the ADMP was modeled as oppositely directed hydraulic jets submerged at the center of the 85-ft diameter tank, with pump suction taken from below. The calculations were based on prototypic tank geometry and nominal operating conditions. In the analysis, the magnitude of the local velocity was used as a measure of slurrying and suspension capability. The computational results showed that normal operations in Tank 18 with the ADMP mixer and a 70-in liquid level would provide adequate sludge removal in most regions of the tank. The exception was the region within about 1.2 ft of the tank wall, based on an historical minimum velocity required to suspend sludge. Sensitivity results showed that a higher tank liquid level and a lower elevation of pump nozzle would result in better performance in suspending and removing the sludge. These results were consistent with experimental observations.

scholarly journals Scale-Up of Solid-Liquid Mixing Based on Constant Power/Volume and Equal Blend Time Using VisiMix Simulation

2018 ◽  
Vol 187 ◽  
pp. 04002
Author(s):  
Megawati ◽  
Bayu Triwibowo ◽  
Karwono ◽  
Waliyuddin Sammadikun ◽  
Rofiatun Musfiroh
Keyword(s):  
Solid Phase ◽  
Scale Up ◽  
Solid Particles ◽  
Liquid Mixing ◽  
Liquid Suspension ◽  
Two Parameters ◽  
Solid Liquid ◽  
Tank Geometry ◽  
Impeller Geometry

Mixing is one of the important process in many areas of chemical industries, for instance pharmaceutical, drug, ink, paint and other industries. Solid-liquid suspension is produced for 80% of all mixing industries such as leaching process, crystallization process, catalytic reactions, precipitation, coagulation, dissolution and other applications. Two main objectives in solid-liquid mixing namely, avoid settling of solid particles on the tank bottom and ensure the solid particles are uniformly distributed. Many factors that can affect the quality of solid-liquid mixing, they are tank geometry, impeller geometry and speed, baffles, viscosity and density of media. Scale-up of the process is important to conduct before produce it on commercial scale. Two parameters for scale-up solid-liquid mixing are equal blend time and power per volume. Before scaling up the process to industrial scale, an engineer must know the condition of the mixture between both of two. VisiMix can simulating scale-up of solid-liquid mixing in order to know the phenomena inside the tank without conducting a large number of experiments and cheaper. The simulation start from keep the ratio of impeller to tank diameter remains constant, then change the condition operation of mixing. In this paper, power per volume parameter is more recommended as a result of the degree of uniformity of solid phase in liquid.

scholarly journals Rapid design of aircraft fuel quantity indication systems via multi-objective evolutionary algorithms

2020 ◽  
pp. 1-18
Author(s):  
David Judt ◽  
Craig Lawson ◽  
Albert S.J. van Heerden
Keyword(s):  
System Level ◽  
Fluid Systems ◽  
Trade Offs ◽  
Aircraft Fuel ◽  
Definition Of ◽  
Tank Geometry ◽  
Probe Set ◽  
Accuracy Constraints ◽  
Good Agreement

The design of electrical, mechanical and fluid systems on aircraft is becoming increasingly integrated with the aircraft structure definition process. An example is the aircraft fuel quantity indication (FQI) system, of which the design is strongly dependent on the tank geometry definition. Flexible FQI design methods are therefore desirable to swiftly assess system-level impact due to aircraft level changes. For this purpose, a genetic algorithm with a two-stage fitness assignment and FQI specific crossover procedure is proposed (FQI-GA). It can handle multiple measurement accuracy constraints, is coupled to a parametric definition of the wing tank geometry and is tested with two performance objectives. A range of crossover procedures of comparable node placement problems were tested for FQI-GA. Results show that the combinatorial nature of the probe architecture and accuracy constraints require a probe set selection mechanism before any crossover process. A case study, using approximated Airbus A320 requirements and tank geometry, is conducted and shows good agreement with the probe position results obtained with the FQI-GA. For the objectives of accessibility and probe mass, the Pareto front is linear, with little variation in mass. The case study confirms that the FQI-GA method can incorporate complex requirements and that designers can employ it to swiftly investigate FQI probe layouts and trade-offs.

Temperature modelling and prediction for activated sludge systems

2009 ◽  
Vol 59 (1) ◽  
pp. 125-131 ◽  
Author(s):  
S. Lippi ◽  
D. Rosso ◽  
C. Lubello ◽  
R. Canziani ◽  
M. K. Stenstrom
Keyword(s):  
Reference Data ◽  
Volume Ratio ◽  
Sensitivity Analyses ◽  
Temperature Model ◽  
Physiochemical Properties ◽  
Aeration System ◽  
Steady State Temperature ◽  
Biomass Activity ◽  
Tank Geometry ◽  
Activated Sludge Systems

Temperature is an important factor affecting biomass activity, which is critical to maintain efficient biological wastewater treatment, and also physiochemical properties of mixed liquor as dissolved oxygen saturation and settling velocity. Controlling temperature is not normally possible for treatment systems but incorporating factors impacting temperature in the design process, such as aeration system, surface to volume ratio, and tank geometry can reduce the range of temperature extremes and improve the overall process performance. Determining how much these design or up-grade options affect the tank temperature requires a temperature model that can be used with existing design methodologies. This paper presents a new steady state temperature model developed by incorporating the best aspects of previously published models, introducing new functions for selected heat exchange paths and improving the method for predicting the effects of covering aeration tanks. Numerical improvements with embedded reference data provide simpler formulation, faster execution, easier sensitivity analyses, using an ordinary spreadsheet. The paper presents several cases to validate the model.

Steady Turning Stability of Partially Filled Tank Vehicles With Arbitrary Tank Geometry

1989 ◽  
Vol 111 (3) ◽  
pp. 481-489 ◽  
Author(s):  
R. Ranganathan ◽  
S. Rakheja ◽  
S. Sankar
Keyword(s):  
Cross Sections ◽  
Optimal Order ◽  
Fluid Structure Interactions ◽  
Plane Model ◽  
Articulated Vehicle ◽  
Turning Response ◽  
The Stability ◽  
Fill Level ◽  
Tank Geometry ◽  
Tank Vehicles

Steady turning model of a partially filled tank vehicle is developed by integrating the roll plane model of the partially filled arbitrarily shaped tank with the static roll plane model of an articulated vehicle. The rollover immunity of the tank vehicle is investigated through computer simulation. The motion of the free surface of liquid and the associated load shift encountered during steady turning are computed using an iterative algorithm. The influence of tank geometry and liquid fill level on the rollover immunity of the tank vehicles is presented. Rollover threshold levels of a tractor-semitrailer vehicle with tanks of circular, modified square and modified oval cross sections are investigated for various fill levels. The influence of compartmenting of the tank on the steady turning response of the vehicle is presented and an optimal order of unloading the various compartments is determined. The study concludes that load shift encountered during steady turning has an adverse effect on the overturning limits of the articulated liquid tank vehicles. The stability of such tank vehicles may be further affected by the dynamic fluid-structure interactions, vehicle transients and driver’s reaction.

Diffused aeration systems from theory to design

1978 ◽  
Vol 5 (1) ◽  
pp. 32-41 ◽  
Author(s):  
Jatinder K. Bewtra ◽  
Donald S. Mavinic
Keyword(s):  
Oxygen Transfer ◽  
Climatic Conditions ◽  
Air Bubbles ◽  
Cold Regions ◽  
Surface Aeration ◽  
Conventional Activated Sludge ◽  
Aeration System ◽  
Tank Geometry ◽  
Counter Current ◽  
Mechanical Surface

Aeration has been used successfully in northern Canada and other cold regions for treating domestic and industrial waste waters by aerated lagoons, extended aeration package units and conventional activated sludge plants. Many of these installations used diffused aeration because this system has shown several advantages over mechanical surface aeration. The advantages of using diffused aeration in cold regions for oxygenation as well as for mixing are discussed in this paper.The parameters affecting the efficiency of oxygen transfer and the mixing of the tank contents are identified and the influence of varying these operating parameters on the performance of diffused aeration systems under cold climatic conditions is discussed. Equations showing the influence of temperature, airflow rates, submergence and tank geometry on the overall oxygen transfer coefficient are presented.A process of aeration, employing counter-current flow of air bubbles and waste water, is shown to result in increased contact time and therefore higher oxygenation efficiencies. A typical example for designing a diffused aeration system in cold regions has been worked out.

CFD Analysis of Vortex-Induced Motions of Bare and Straked Cylinders in Currents

2005 ◽  
Author(s):  
K. P. Thiagarajan ◽  
Y. Constantinides ◽  
L. Finn
Keyword(s):  
Turbulence Modeling ◽  
Equations Of Motion ◽  
Transverse Displacement ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Hexahedral Elements ◽  
Helical Strakes ◽  
Truss Spar ◽  
Uniform Currents ◽  
Tank Geometry

It is widely acknowledged that the use of helical strakes for mitigation of vortex-induced motions (VIM) of surface piercing cylinders, such as spar platforms, is only partially effective. Using computational fluid dynamics tools, we compare the oscillation characteristics of a bare cylinder and a straked cylinder in uniform currents. Our model comprised of a straked cylinder with diameter of 0.741 m, aspect ratio of 1:1.9 and three helical strakes of height 13% of cylinder diameter. This geometry corresponds to the hard tank geometry of a scaled truss spar model known to exhibit VIM in tow tank testing. In the CFD simulations the cylinder is moored with linear springs to provide a range of reduced velocities. The fluid domain is made of an unstructured grid comprising of hexahedral elements. Fluid structure interaction utilizes grid stretching and a user defined function for solving the equations of motion. Turbulence modeling uses Detached Eddy Simulation (DES) and the boundary layer is modeled using a wall function with a surface roughness of 0.0003 m. Reynolds numbers are in the range of 50,000 to 100,000. Results for straked cylinder compares reasonably with published results, but under-predicts the peak response. In comparing with corresponding results for a bare cylinder without strakes, the spectral features of the transverse displacement show variations, which are found to be due to the spoiling effect of the strakes.

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