The Precipitation of the Nanoparticles by the Thermophoresis at the Cryogenic Temperatures

1998 ◽  
Vol 520 ◽  
Author(s):  
O.L. Khasanov ◽  
Yu.P Pokholkov ◽  
V.P. Krivobokov ◽  
T.V. Milovanova

ABSTRACTThe conditions of nanodispersed particles precipitation from a gas flow on the surface cooled to cryogenic temperatures are analyzed. The range of allowable values of precipitation surface temperature has been defined in dependence of dispersed flow characteristics. The method can be used both for catching of nanopowders, and for gas cleaning from aerosol and dust particles for ecological purposes.

2021 ◽  
Vol 1 (2021) ◽  
pp. 28-32
Author(s):  
Daniela-Elena Jugănaru ◽  
Mariana Panaitescu ◽  
Liviu-Constantin Stan

" In this study, gas flow field were simulated using ANSYS 2020R2, Fluid Flow Fluent computational fluids dynamic (CFD) software based on the continuity, velocity, temperature, energy and k -  turbulence. The overall objective of the study is to compare the pressure and velocity maps inside the wet scrubber system for two different scrubber designs. I have choose to analyse an In-Line scrubber bottom inlet, type I, and In-Line scrubber side inlet, type L. Bottom entry or side entry designs to allow a direct up-flow configuration and simplify engine exhaust gas duct routing for any type of vessel. The flow in a wet scrubber is very complex due to the interaction between dust particles, water droplets, and bulk water and flue gas. The flue gas flow is turbulent and there are multiple phases (gas, liquid and solid). CFD codes that predict gas flow patterns are based on conservation equations for mass, momentum and energy. The results show that the residuals have a very good job of converging at minimum flow contours and vectors at the inlet across the scrubbing chamber and outlet shows a distributed flow. The velocity profiles have fully conformed to the recommended profile for turbulent flow in pipes. As can be seen in the figures above, the velocity flow contour inside the scrubber is higher in the scrubber side inlet. Even though I choose to study the simplified scrubber model without taking into account that spray nozzle improve mixing between the scrubbing liquid and waste gas; from the results obtained, it can be deduced that the numerical simulation using CFD is an effective method to study the flow characteristics of a counter-flow wet scrubber system. "


2021 ◽  
Vol 88 ◽  
pp. 103826
Author(s):  
Yiyu Lu ◽  
Jiankun Zhou ◽  
Honglian Li ◽  
Jiren Tang ◽  
Lei Zhou ◽  
...  

Author(s):  
Arash Farahani ◽  
Peter Childs

Strip seals are used in gas turbine engines between two static elements or between components which do not move relative to each other, such as Nozzle Guide Vanes (NGVs). The key role of a strip seal between NGV segments is sealing between the flow through the main stream annulus and the internal air system, a further purpose is to limit the inter-segmental movements. In general the shape of the strip seal is a rectangular strip that fits into two slots in adjacent components. The minimum clearance required for static strip seals must be found by accounting for thermal expansion, misalignment, and application, to allow correct fitment of the strip seals. Any increase in leakage raises the cost due to an increase in the cooling air use, which is linked to specific fuel consumption, and it can also alter gas flow paths and performance. The narrow path within the seal assembly, especially the height has the most significant affect on leakage. The height range of the narrow path studied in this paper is 0.01–0.06 mm. The behaviour of the flow passing through the narrow path has been studied using CFD modelling and measurements in a bespoke rig. The CFD and experimental results show that normalized leakage flow increases with pressure ratio before reaching a maximum. The main aim of this paper is to provide new experimental data to verify the CFD modelling for static strip seals. The typical flow characteristics validated by CFD modelling and experiments can be used to predict the flow behaviour for future static strip seal designs.


2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Sadia Siddiqa ◽  
Naheed Begum ◽  
M. A. Hossain ◽  
Rama Subba Reddy Gorla

This article is concerned with the class of solutions of gas boundary layer containing uniform, spherical solid particles over the surface of rotating axisymmetric round-nosed body. By using the method of transformed coordinates, the boundary layer equations for two-phase flow are mapped into a regular and stationary computational domain and then solved numerically by using implicit finite difference method. In this study, a rotating hemisphere is used as a particular example to elucidate the heat transfer mechanism near the surface of round-nosed bodies. We will investigate whether the presence of dust particles in carrier fluid disturbs the flow characteristics associated with rotating hemisphere or not. A comprehensive parametric analysis is presented to show the influence of the particle loading, the buoyancy ratio parameter, and the surface of rotating hemisphere on the numerical findings. In the absence of dust particles, the results are graphically compared with existing data in the open literature, and an excellent agreement has been found. It is noted that the concentration of dust particles’ parameter, Dρ, strongly influences the heat transport rate near the leading edge.


2013 ◽  
Vol 13 (5) ◽  
pp. 1330-1356 ◽  
Author(s):  
G. H. Tang ◽  
G. X. Zhai ◽  
W. Q. Tao ◽  
X. J. Gu ◽  
D. R. Emerson

AbstractGases in microfluidic structures or devices are often in a non-equilibrium state. The conventional thermodynamic models for fluids and heat transfer break down and the Navier-Stokes-Fourier equations are no longer accurate or valid. In this paper, the extended thermodynamic approach is employed to study the rarefied gas flow in microstructures, including the heat transfer between a parallel channel andpressure-driven Poiseuille flows through a parallel microchannel andcircular microtube. The gas flow characteristics are studied and it is shown that the heat transfer in the non-equilibrium state no longer obeys the Fourier gradient transport law. In addition, the bimodal distribution of streamwise and spanwise velocity and temperature through a long circular microtube is captured for the first time.


1982 ◽  
Vol 21 (12) ◽  
pp. 938-940
Author(s):  
A. A. Antonov ◽  
A. É. Bespalov

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