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1.
During the flow around spherical inclusions in a homogeneous porous medium, the gas flow field is calculated using the Brinkman equation. The expression is derived for the effective permeability of the porous medium containing the rarefied ensemble of randomly arranged dispersed spherical particles of arbitrary sizes. It is shown that the Darcy approximation is applicable to the large-size inclusions. The influence of dispersed inclusions of spheroidal shape on both the pressure drop and the efficiency of aerosol particle collection with a filter is studied in the Darcy approximation. It is shown that dispersed inclusions can both increase and decrease the quality criterion of a filter depending on the values of parameters. 相似文献
2.
Theoretical approach to the optimization of the parameters of two-stage fibrous aerosol filter is reported. The approach is based on earlier developed method for the calculation of the clogging of model filter where the particle deposit is approximated by the porous shell on the fibers. The values of optimal fiber radii are determined from the condition of maximal dust capacity of a filter at given limiting pressure drop and total initial efficiency. Optimization was performed with allowance for possible variation in the prefilter thickness. 相似文献
3.
A.I. Kokorin K.I. Zamaraev V.Ya. Kovner Yu.E. Kirsh V.A. Kabanov 《European Polymer Journal》1975,11(10):719-722
Cu(II) complexes of poly-2-vinylpyridine (P2VP) and poly-2-methyl-5-vinylpyridine (P2M5VP), partially quaternized by dimethylsulphate, and of the analogues (2-methyl-5-ethylpyridine, 2-ethylpyridine) were studied by EPR spectroscopy in a mixture of methanol and water. Peculiarities of the complex formation reaction were observed for the polymers compared to the analogues. At ratios of [Py]:[Cu2+] > 40, the predominant formation of tetrapyridinate-Cu(II) species [(CuL4)]2+ was found for P2M5VP. However, differences were found between the parameters of EPR-spectra for the [CuL4]2+ in the polymer from that of the [Cu(2M5EPy)4]2+. It was suggested that, in the polymer, [CuL4]2+ complexes with structure intermediate between square planar and tetrahedral are formed. Moreover, the maximum value of the pyridine fraction forming [CuL4]2+ in P2M5VP was found to be about 10% and it is appreciably less the value of the fraction in P4VP (about 40%). For P2VP at [Py]:[Cu2+] > 40, an insignificant amount of [CuL1]2+ and [CuL2]2+ are formed in the solution. It follows that the main chain position relative to the ligand nitrogen atom in these polyvinylpyridines affects profoundly the complexation between the macromolecules and Cu(II) ions. The steric hindrances due to the chain are likely to change the [CuL4]2+ structure and to prevent complex formation for P2VP. 相似文献
4.
Interaction between small molecules (iodine and 1-anilinonaphthalene-8-sulphonate) and poly-N-methylacetamide (PVMA), poly-N-vinylcaprolactam (PVCL), poly-N-vinylpyrrolidone (PVP) and copolymers of N-vinyleaprolactam with N-vinylpyrrolidone (CP VCL-VP) and with N-vinyl-N-methylacetamide (VMA) were studied. All the polymers formed complexes with the small molecules. The stability constant for the complexes with the probe increases in the series PVMA < PVP < copolymer < PVCL indicating the essential role of hydrophobic interactions in the complex formation. With increasing temperature of aqueous solution from 18 to 33°, the constant decreased for PVP, PVMA and copolymers with low VCL content and increased for PVCL. A folding of PVC coils was observed over the temperature range, demonstrating a relationship between the conformational changes of macromolecules and the polymer complex formation. Addition of PVCL, PVMA and PVP to aqueous I3? solution brings about a shift of λmax from 350 nm for free triiodide ions to 372, 367 and 364 nm respectively. It is explained by different dipole moments of the side substituents. The stability constant for the polymers and I3? was estimated as approx. 105 M. The ability of the polymers to form complexes depends on chainlength. The greatest loss of the ability was observed for PVCL with changing from 6 × 103 to 2 × 103. Interaction of the polymers with I3? is accompanied by a conformational shrinking of coils. In the case of the probe, forces of electrostatic repulsion between negative charges of sulphonate groups result in an unfolding of polimer coils. 相似文献
5.
The influence of the inertia of a viscous incompressible liquid flow on the viscous drag and diffusion deposition of particles in model granular filters at Reynolds numbers higher than unity, Re > 1, has been considered. The granule drag forces and particle-collection efficiencies in isolated layers with square and hexagonal packings of granules have been calculated. The influence on each other of approaching monolayers of granules on pressure drop and nanoparticle deposition has been studied. It has been shown that, at Re > 1, the collection efficiency dramatically increases due to the effect of interception. 相似文献
6.
The penetration coefficient of hydrosol particles through the irregular fibrous filter as a function of their radii was calculated for a sieve mechanism of capture. 相似文献
7.
The deposition of aerosol nanoparticles from Stokes flows in screen-type diffusion batteries designed for the determination
of diffusion coefficients for suspended nanoparticles is considered. Average fiber collection efficiencies η calculated for
screens consisting of two perpendicularly contacting rows of parallel equidistant straight fibers agree with the experimental
data obtained for woven screens within the Peclet number range Pe = 0.15−1000. It is shown that, for dense screens, the η
∼ Pe−2/3 power dependence is valid at Pe > 10. For rarefied screens, this dependence is fulfilled down to Pe ∼ 0.1. At Pe ≪ 1, the
integral flow of particles advancing on the fibers of the first row in the screen and the fiber collection efficiency, η of
an isolated row tends to a geometrical limit, which is equal to the ratio of the distance between the axes of the fibers to
the fiber diameter. 相似文献
8.
A. A. Kirsh 《Colloid Journal》2017,79(1):61-75
Generation of aerosols by electrostatic spraying of liquids from the tip of a needle placed into a capillary has been studied at a voltage lower than that corresponding to the corona ignition in the regime of the formation of single monodisperse droplets. The peculiarities of the jet-type motion of low-volatile liquid droplets with submicron sizes have been considered. 相似文献
9.
The inertial deposition of submicron aerosol nanoparticles onto fibers during gas filtration through fine-fiber filters is
considered. It is shown that there is critical filtration velocity U* below which the energy loss upon collisions has no influence on the filtration efficiency. Above this critical velocity,
the filtration efficiency depends on the mechanism of the inelastic energy loss and can be noticeably lower than the result
of its estimation with no allowance for the particle rebound. For a rather dense fibrous medium, when not all particles that
have rebounded from a fiber have time to attain the flow velocity before the next collision with another fiber, the filtration
efficiency depends on the velocity distribution of the rebounding particles. It is shown that, in this case, the filtration
efficiency must increase with the packing density of a filter. 相似文献
10.
V. A. Kirsh 《Colloid Journal》2011,73(4):478-481
The deposition of weakly charged aerosol nanoparticles onto fibers in a diffusion battery designed to measure the diffusion
coefficients of particles is considered. The fiber collection efficiancies as functions of particle size and charge are determined
by the numerical solution of the equation of convective diffusion in a system of parallel uncharged fibers located normal
to a flow. It is shown of effect of the single charge of nanoparticles produced by a differential mobility analyzer on their
deposition is negligible and may be ignored when calibrating diffusion batteries. 相似文献