Measurement of Impurity Concentration in Turbulent Flows of Ventilation Systems Channels

Abstract The work is devoted to the experimental study of the process of impurities diffusion in the circular cylindrical channel and the determination of the coordinates of the average concentration of impurities in the turbulent flow. To ensure the uniformity for the aerosols composition during the studies, the experiments were carried out with solid particles of narrow fractional composition. The use of fine-grained oxide catalyst made it possible to obtain the almost monodisperse material. The experimental installation included the volumetric doser for impurity material, the ejector, the concentration sensor, the section of the vertical pipeline, and manometers for recording the pressure in the system. It is shown that the theoretical and experimental results are in satisfactory agreement with each other, and the existing discrepancy can be explained both by the measurement error and by the presence of spiral motion for the solid phase in the ascending flow. Based on the experiments, it was concluded that the known mathematical positions are adequate and internally not contradictory models of the diffusion process of the impurity substance in the turbulent flow, which can be used to analyze the distribution of the impurity concentration in the channels of the ventilation systems. The results of the studies performed should be taken into account when developing systems for measuring and monitoring the gas-air emissions characteristics of the ventilation systems of industrial enterprises.

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Determination of conditions for spontaneous combustion of combustible dust deposits on equipment, in ventilation systems, and aspiration systems of buildings and structures

ПОЖАРОВЗРЫВОБЕЗОПАСНОСТЬ ◽

10.22227/pvb.2020.29.04.32-41 ◽

2020 ◽

Vol 29 (4) ◽

pp. 32-41

Author(s):

L. P. Vogman ◽

D. A. Korolchenko ◽

A. V. Khryukin

Keyword(s):

Spontaneous Combustion ◽

Growth Dynamics ◽

Operating Conditions ◽

Industrial Enterprises ◽

Process Characteristics ◽

Industrial Buildings ◽

Dust Deposits ◽

Production Facilities ◽

Ventilation Systems

Introduction. Determination of the scientifi cally substantiated frequency of cleaning the ducts of local exhausts of industrial buildings and structures is one of the tasks in the fi eld of fi re safety of industrial enterprises. The paper describes design methods, in particular, a method for determination of the induction period during spontaneous combustion of dust deposits in air ducts of ventilation systems and equipment, which can be used in solving problems focused on the development of preventive measures to ensure their fi re and explosion safety.Methods. In order to solve the problem set in this paper and compare the indicators obtained in the calculation and analytical part of the studies with the growth dynamics of deposits in real facilities, fi eld tests have been accomplished in the production facilities of the fl our mill of OJSC MK “Voronezhsky” and JSC Concern “Sozvezdiye”.Results and discussion. The timeframes for cleaning of deposits on ventilation (aspiration) equipment of buildings and structures cannot be universal for various industries and must take into account the dynamics of the growth of deposits depending on the specifi cs of combustible deposits, the workload of the production facilities of the protected object in a given period of time, and the operating conditions of the equipment. As a result of the experiments, it was found that the places of maximum accumulations of deposits are most often formed on the surfaces of joints and on the bends of pipelines of ventilation systems. The conditions of spontaneous combustion of combustible dust are studied by calculation and analytical method, depending on such process characteristics as the speed of the dust-air mixture fl ow in the duct, as well as the diameter of the duct’s cross section.Conclusions. The nomograms built on the basis of the studies performed can be used to determine the multiplicity of cleaning of combustible dusts of equipment and air ducts of industrial ventilation systems. The paper provides a calculation of the period of induction of spontaneous combustion of combustible dust deposits using the example of rye fl our with asymmetric heat transfer. Its signifi cance is due to the process of accumulation of deposits of combustible dust to a critical thickness in terms of spontaneous combustion conditions.

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Identification and quantification of organic pollutants in the air of the city of Astana using solid phase microextraction

Chemical Bulletin of Kazakh National University ◽

10.15328/cb826 ◽

2017 ◽

pp. 14-17

Author(s):

Dina Orazbayeva ◽

Ulzhalgas Karatayeva ◽

Kulzhan Beysembayeva ◽

Kulyash Meyramkulova

Keyword(s):

Polycyclic Aromatic Hydrocarbons ◽

Aromatic Hydrocarbons ◽

Solid Phase Microextraction ◽

Solid Phase ◽

Ambient Air ◽

Average Concentration ◽

Polycyclic Aromatic ◽

Benzene Toluene ◽

The City

Solid-phase microextraction in combination with gas chromatography and mass-spectrometry (GC-MS) was used for determination of benzene, toluene, ethylbenzene and o-xylene (BTEX), polycyclic aromatic hydrocarbons (PAH), and for identification of volatile organic compounds (VOCs) in ambient air of the city of Astana, Kazakhstan. The screening of the samples showed the presence of mono- and polycyclic aromatic hydrocarbons, alkanes, alkenes, phenols, and benzaldehydes. The concentrations of naphthalene were 5-7 times higher than the permissible value, it was detected in all studied air samples. Average concentration of naphthalene was 18.4 μg/m3, acenaphthylene – 0.54 μg/m3, acenaphthene – 1.63 μg/m3, fluorene – 0.79 μg/m3, anthracene – 3.27 μg/m3, phenanthrene – 0.22 μg/m3, fluorantene – 0.74 μg/m3, pyrene – 0.73 μg/m3. Average concentrations of BTEX in the studied samples were 31.1, 84.9, 10.8 and 11.6 μg/m3, respectively. Based on the statistical analysis of the concentrations of BTEX and PAH, the main source of city air pollution with them was assumed to be vehicle emissions.

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Some Problems of Statistical Modeling of Intermittent Turbulent Flows and Their Solutions

Volume 7A: Fluids Engineering Systems and Technologies ◽

10.1115/imece2015-50499 ◽

2015 ◽

Author(s):

Yu. V. Nuzhnov

Keyword(s):

Differential Equations ◽

Turbulent Flow ◽

Statistical Modeling ◽

Turbulent Flows ◽

Impurity Concentration ◽

Inhomogeneous Field ◽

Passive Impurity ◽

Turbulent Fluid ◽

Admixture Concentration ◽

Passive Admixture

Some problems of statistical modeling of turbulent flows associated with the hydrodynamic effects of intermittency of various dynamic and scalar fields are identified, and a justification of their solutions is proposed. At first examines some problems of statistical modeling of large-scale (energy-containing) turbulence structure under the conditions of turbulent and nonturbulent fluid intermittency in the turbulent flow. This primarily applies to the problem of obtaining the differential equations of hydrodynamics for conditional statistical moments (conditional averages), i.e. for single-point statistical moments of each of the intermittent media of turbulent flow. To solve this problem is given a mathematically rigorous justification of conducting the operation of conditional averaging of the Navier-Stokes equations. As a result was obtained the system of differential equations for the conditional averages of turbulent and nonturbulent fluid. The main advantage of the obtained differential equations for the conditional averages is that these equations don’t contain the source terms. Therewith is given a physical substantiation of transformation process of nonturbulent fluid in turbulent, that occurs in a thin superlayer, which separates turbulent and nonturbulent fluid. Here also is given a justification of conducting the operation of total averaging of the partial derivates, which, as it turns out, is not a permutational and leads to a number of specific features in comparison with the unconditional averaging in RANS. Another problem associated with statistical modeling of inhomogeneous turbulent flows, i.e. flows with an inhomogeneous field of scalar substance. It is known that the dynamic field with turbulent fluid does not coincide with the inhomogeneous field of scalar substance. To solve this problem is proposed a method of calculating the statistical characteristics both of the turbulent fluid and the inhomogeneous field of a passive admixture concentration. It is shown, that the conditional averages of the passive admixture concentration are significantly different. In conclusion we consider the problem of statistical modeling of diffusional turbulent combustion of not pre-mixed chemically reacting gases, expressly the modeling by the known method PDF with involving the “reduced fuel concentration” as the passive impurity concentration. To solve this problem is given a justification of new differential equations, allowing to carry out calculations only of the conditional averages for the intersection region of the dynamic field of the turbulent fluid and the inhomogeneous field of the passive impurity concentration. Some results of such calculations, performed in the self-similar field of diffusion turbulent propane plume, are presented together with the experimental data available in literature.

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Comparison of Protein Precipitation, Turbulent Flow and Automated On-Line Solid Phase Extraction, as Plasma Sample Preparation Techniques for the Determination of Compound I by LC-MS-MS

Chromatographia ◽

10.1365/s10337-003-0171-y ◽

2004 ◽

Vol 59 (S2) ◽

Cited By ~ 5

Author(s):

S. Calderoli ◽

E. Frigerio ◽

C. A. James

Keyword(s):

Sample Preparation ◽

Solid Phase Extraction ◽

Turbulent Flow ◽

Plasma Sample ◽

Solid Phase ◽

Phase Extraction ◽

Compound I ◽

On Line ◽

Preparation Techniques

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Determination of Ivermectin in Salmon Muscle Tissue by Liquid Chromatography with Fluorescence Detection

Journal of AOAC International ◽

10.1093/jaoac/81.3.549 ◽

1998 ◽

Vol 81 (3) ◽

pp. 549-553 ◽

Cited By ~ 4

Author(s):

Heidi S Rupp ◽

Sherri B Turnipseed ◽

Calvin C Walker ◽

José E Roybal ◽

Austin R Long

Keyword(s):

Atlantic Salmon ◽

Limit Of Detection ◽

Solid Phase ◽

Average Concentration ◽

Baseline Noise ◽

Muscle Tissues ◽

Relative Standard ◽

Fluorescent Moiety ◽

Liquid Chromatographic

abstract A liquid chromatographic method was developed for determination of ivermectin B1a (IVR) extracted from raw fortified and incurred Atlantic salmon muscle tissues. The method was also used to determine fortified doramectin (DOR) in Atlantic salmon. Tissue extract was applied to a C8 solid-phase extraction (SPE) column, followed by a silica SPE column. Residues in the eluate were treated with trifluoroacetic anhydride and methylimidazole to dehydrate the IVR molecule and form an aromatic fluorescent moiety with a trifluoroacetic ester. This product was subsequently treated with ammonium acetate in methanol to cleave the ester and convert the functional group back to a stable alcohol form. The analytes were determined by fluorescence with excitation at 272 nm and emission at 465 nm. A Cis Hypersil column was used for analysis with a mobile phase of acetonitrile-water (90 + 10, v/v) and an oven temperature of 65°C. IVR and DOR were determined at 5 fortification levels (1, 5,10, 20, and 40 ppb). Intra-assay absolute recoveries ranged from 75 to 89% for IVR and from 73 to 85% for DOR. Relative standard deviations (RSDs) were <7% in all cases. The limit of detection (3 x baseline noise) was 0.25 ppb extracted from tissue. Incurred tissues had an average concentration of 32 ppb, with an RSD of 3%.

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Determination of Mechanical Energy Loss in Steady Flow by Means of Dissipation Power

Archives of Hydro-Engineering and Environmental Mechanics ◽

10.1515/heem-2017-0005 ◽

2017 ◽

Vol 64 (2) ◽

pp. 73-85 ◽

Cited By ~ 3

Author(s):

Wojciech Artichowicz ◽

Jerzy M. Sawicki

Keyword(s):

Energy Loss ◽

Turbulent Flow ◽

Turbulent Flows ◽

Mechanical Energy ◽

Turbulent Viscosity ◽

Viscosity Coefficient ◽

Mechanical Energy Loss ◽

Different Types ◽

Loss Determination

Abstract When systems of simple geometry like pipes or regular channels are considered, the mechanical energy loss of the fluid flow can be expressed by local and longitudinal empirical energy loss coefficients. However, in the case of large spatially distributed objects, there are no simple approaches to this task. In practice, general recommendations addressing different types of objects are used, but they usually provide very coarse estimates of energy loss. In this work, a new methodology for determination of mechanical energy loss in steady flowis proposed. This methodology is based on the observation that the magnitude of the power of energy dissipation in turbulent flow can be determined using the averaged flow velocity and turbulent viscosity coefficient. To highlight this possibility, an analysis of the magnitudes of the power of the main and fluctuating components of turbulent flow is presented. The correctness of the method is verified using an example of laminar and turbulent flows in a circular pipe. The results obtained show clearly that the proposed methodology can be used for mechanical energy loss determination in flow objects. This methodology can be used as a basis for mechanical energy loss determination in different types of flow objects.

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218. Determination of Formaldehyde Using Solid Phase Microextraction for Both Instantaneous and Timeweighted Average Sampling

10.3320/1.2762606 ◽

1999 ◽

Author(s):

P.A. Martos ◽

J. Pawliszyn

Keyword(s):

Solid Phase Microextraction ◽

Solid Phase ◽

Average Sampling

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Modern determinants of endometrium hyperplastic processes pathogenesis

HEALTH OF WOMAN ◽

10.15574/hw.2016.111.137 ◽

2016 ◽

pp. 137-142

Author(s):

V.O. Benyuk ◽

◽

V.M. Goncharenko ◽

T.R. Nykoniuk ◽

◽

...

Keyword(s):

Conservative Therapy ◽

Solid Phase ◽

Research Direction ◽

Immunohistochemical Method ◽

Results Of Treatment ◽

Treatment And Prevention ◽

Receptor Phenotype ◽

The Relationship ◽

Endometrial Proliferation

The objective: to еxplore the relationship between the activity of endometrial proliferation and the state of the local immune response in the uterus in the conditions berprestasi process. Patients and methods. Examined 228 women of reproductive and perimenopausal age with endometrial pathology using ultrasound and then performing hysteroresectoscopy. Determination of the concentrations of the cytokines IL-1, IL-2, IL-6 and TNF was performed by solid phase ELISA. Results. Found a trend that confirms the loss of sensitivity to hormones at the stage of malignancy of the endometrium and can be used as diagnostic determinants in determining the nature of intrauterine pathology and criterion of the effectiveness of conservative therapy. Conclusion. Improving etiopatogenetice approach to the therapy of hyperplastic proce.sses of endometrium with determination of receptor phenotype of the endometrium is a research direction in modern gynecology, which will help to improve the results of treatment and prevention of intrauterine pathology. Key words: endometrial hyperplasia,the receptors for progesterone and estrogen, immunohistochemical method.

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