Investigation of the effect of bellows on the separation power in a gas centrifuge using DSMC method

2022 ◽  
Vol 169 ◽  
pp. 108955
Author(s):  
Sadegh Yousefi-Nasab ◽  
Jaber Safdari ◽  
Javad Karimi-Sabet ◽  
Masoud Khajenoori ◽  
Mohamad hasan Mallah ◽  
...  
Keyword(s):  
Dsmc Method ◽  
Separation Power ◽  
Gas Centrifuge

Comparison of DSMC and CFD Models of Heat Transfer in a Rarefied Two-Dimensional Geometry

2018 ◽  
Author(s):  
Dilesh Maharjan ◽  
Mustafa Hadj-Nacer ◽  
Miles Greiner ◽  
Stefan K. Stefanov
Keyword(s):  
Heat Transfer ◽  
Rarefied Gas ◽  
Complex Geometry ◽  
Direct Simulation Monte Carlo ◽  
Accurate Method ◽  
Vacuum Drying ◽  
Helium Pressure ◽  
Two Dimensional ◽  
Dsmc Method ◽  
Cfd Simulations

During vacuum drying of used nuclear fuel (UNF) canisters, helium pressure is reduced to as low as 67 Pa to promote evaporation and removal of remaining water after draining process. At such low pressure, and considering the dimensions of the system, helium is mildly rarefied, which induces a thermal-resistance temperature-jump at gas–solid interfaces that contributes to the increase of cladding temperature. It is important to maintain the temperature of the cladding below roughly 400 °C to avoid radial hydride formation, which may cause cladding embrittlement during transportation and long-term storage. Direct Simulation Monte Carlo (DSMC) method is an accurate method to predict heat transfer and temperature under rarefied condition. However, it is not convenient for complex geometry like a UNF canister. Computational Fluid Dynamics (CFD) simulations are more convenient to apply but their accuracy for rarefied condition are not well established. This work seeks to validate the use of CFD simulations to model heat transfer through rarefied gas in simple two-dimensional geometry by comparing the results to the more accurate DSMC method. The geometry consists of a circular fuel rod centered inside a square cross-section enclosure filled with rarefied helium. The validated CFD model will be used later to accurately estimate the temperature of an UNF canister subjected to vacuum drying condition.

scholarly journals Enhancing biological analyses with three dimensional field asymmetric ion mobility, low field drift tube ion mobility and mass spectrometry (μFAIMS/IMS-MS) separations

The Analyst ◽  
2015 ◽  
Vol 140 (20) ◽  
pp. 6955-6963 ◽  
Author(s):  
Xing Zhang ◽  
Yehia M. Ibrahim ◽  
Tsung-Chi Chen ◽  
Jennifer E. Kyle ◽  
Randolph V. Norheim ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ion Mobility ◽  
Drift Tube ◽  
Three Dimensional ◽  
Separation Power ◽  
Low Field ◽  
Field Drift

Novel μFAIMS/IMS-MS three dimensional separations were optimized to enhance separation power and selectivity in biological analyses.

Investigation of the Squeeze Film Dynamics Underneath a Microstructure With Large Oscillation Amplitudes and Inertia Effects

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Nadim A. Diab ◽  
Issam A. Lakkis
Keyword(s):  
Rarefied Gas ◽  
Direct Simulation Monte Carlo ◽  
Squeeze Film ◽  
Dsmc Method ◽  
Inertia Effects ◽  
Flow Parameters ◽  
Fluid Behavior ◽  
Dimensionless Groups ◽  
Simulation Monte Carlo ◽  
The Impact

This paper presents direct simulation Monte Carlo (DSMC) numerical investigation of the dynamic behavior of a gas film in a microbeam. The microbeam undergoes large amplitude harmonic motion between its equilibrium position and the fixed substrate underneath. Unlike previous work in literature, the beam undergoes large displacements throughout the film gap thickness and the behavior of the gas film along with its impact on the moving microstructure (force exerted by gas on the beam's front and back faces) is discussed. Since the gas film thickness is of the order of few microns (i.e., 0.01 < Kn < 1), the rarefied gas exists in the noncontinuum regime and, as such, the DSMC method is used to simulate the fluid behavior. The impact of the squeeze film on the beam is investigated over a range of frequencies and velocity amplitudes, corresponding to ranges of dimensionless flow parameters such as the Reynolds, Strouhal, and Mach numbers on the gas film behavior. Moreover, the behavior of compressibility pressure waves as a function of these dimensionless groups is discussed for different simulation case studies.

Numerical Simulation of Chemical Reactions on Rarefied Plasma Plume by DSMC Method

2021 ◽  
Vol 49 (3) ◽  
pp. 1214-1226
Author(s):  
Yongyuan Su ◽  
Jie Li ◽  
Haoyu Wang ◽  
Ao Xu
Keyword(s):  
Numerical Simulation ◽  
Chemical Reactions ◽  
Plasma Plume ◽  
Dsmc Method

Integration of Liquid Chromatography with Immunoassay: An Approach Combining the Strengths of Both Methods

1994 ◽  
Vol 77 (5) ◽  
pp. 1275-1287 ◽  
Author(s):  
Petra M Krämer ◽  
Qing X Li ◽  
Bruce D Hammock
Keyword(s):  
Liquid Chromatography ◽  
Sensitivity And Specificity ◽  
Immunosorbent Assay ◽  
Uv Detection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Multiresidue Analysis ◽  
Selective Method ◽  
Separation Power ◽  
Immunochemical Detection ◽  
Very High

Abstract The integration of liquid chromatography (LC) with immunochemical detection combines the superior separation power of LC and the sensitivity and specificity of immunoassays. This approach is shown with 3 LC systems (Perkin-Elmer, C18 RP, 4.6 mm; Varian, C18 RP, 1 mm microbore; Michrom, C18 RP, 1 mm microbore) Integrated with an enzyme-linked immunosorbent assay (ELISA) selective for five 4-nitrophenols. The nitrophenols were separated with the 3 LC systems with isocratic runs of 15 to 20 min. Microbore LC separation showed a 10-20 times reduction in solvent amount compared to conventional separation. LC–immunoassay was about 8- to 10-fold more sensitive compared with LC with UV detection. Integrated LC–immunoassay proved to be a very selective method when 2-methylphenol was injected with an equimolar mixture of 2-amino-4-nitrophenol and 3-methyl-4-nrtrophenol; 2-methy I phenol does not crossreact with the serum used. Only 2 peaks could be seen in the detection, even when 2-methylphenol was present in very high amounts (3000 pmol). Further, the EUSA-LC detection proved to be selective and sensitive for complex matrixes. 2-Amlno-4-nitrophenol was clearly identified in spiked extracts of soil and plant, even when a very small amount (2.4 ng) was injected. Although LC–immunoassay is more labor intensive than LC with UV detection, it offers great advantages in multiresidue analysis and is generally applicable for peak confirmation.

Simulation of the heat exchange between the supersonic flow and the stationary body in a gas centrifuge

2012 ◽  
Vol 85 (6) ◽  
pp. 1382-1389
Author(s):  
K. V. Zvonarev ◽  
V. D. Seleznev ◽  
V. I. Tokmantsev ◽  
Yu. V. Abramov
Keyword(s):  
Heat Exchange ◽  
Supersonic Flow ◽  
Gas Centrifuge

Study of Gas Flow in Micronozzles Using an Unstructured DSMC Method

2009 ◽  
Author(s):  
Ehsan Roohi ◽  
Masoud Darbandi ◽  
Vahid Mirjalili
Keyword(s):  
Boundary Layer ◽  
Knudsen Number ◽  
Gas Flow ◽  
Subsonic Flow ◽  
Flow Behavior ◽  
Boundary Layer Separation ◽  
Back Pressure ◽  
Viscous Force ◽  
Dsmc Method ◽  
Wide Range

The current research uses an unstructured direct simulation Monte Carlo (DSMC) method to numerically investigate supersonic and subsonic flow behavior in micro convergent–divergent nozzle over a wide range of rarefied regimes. The current unstructured DSMC solver has been suitably modified via using uniform distribution of particles, employing proper subcell geometry, and benefiting from an advanced molecular tracking algorithm. Using this solver, we study the effects of back pressure, gas/surface interactions (diffuse/specular reflections), and Knudsen number, on the flow field in micronozzles. We show that high viscous force manifesting in boundary layers prevents supersonic flow formation in the divergent section of nozzles as soon as the Knudsen number increases above a moderate magnitude. In order to accurately simulate subsonic flow at the nozzle outlet, it is necessary to add a buffer zone to the end of nozzle. If we apply the back pressure at the outlet, boundary layer separation is observed and a region of backward flow appears inside the boundary layer while the core region of inviscid flow experiences multiple shock-expansion waves. We also show that the wall boundary layer prevents forming shocks in the divergent part. Alternatively, Mach cores appear at the nozzle center followed by bow shocks and an expansion region.

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