Determining the diffusion flows and concentration distribution of ternary diffusion

Analytical solutions converging rapidly at large and small values of times have been obtained for two mathematical models which describe the concentration distribution of a non reactive pollutant from a point source against the flow in a horizontal cross-section of a finite saturated shallow aquifer possessing uniform horizontal groundwater flow. Zero concentration or the conditions in which the flux across the extreme boundaries are proportional to the respective flow components are applied. The effects of flow and dispersion on concentration distribution are also discussed.

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Measured and Modelled Chlorinated Contaminant Distributions in the St. Clair River Water

Water Quality Research Journal ◽

10.2166/wqrj.1986.029 ◽

1986 ◽

Vol 21 (3) ◽

pp. 332-343 ◽

Cited By ~ 4

Author(s):

C.H. Chan ◽

Y.L. Lau ◽

B.G. Oliver

Keyword(s):

River Water ◽

Suspended Sediment ◽

Water Samples ◽

Concentration Distribution ◽

Suspended Solids ◽

Industrial Area ◽

Concentration Profiles ◽

Detroit River ◽

Chemical Partitioning ◽

Transverse Mixing

Abstract The concentration distribution of hexachlorobutadiene (HCBD), pentachloro-benzene (QCB), hexachlorobenzene (HCB) and octachlorostyrene (OCS) in water samples from transects across the upper and lower St. Clair River and the upper Detroit River were determined on four occasions in 1985. The data show a plume of these contaminants from the Sarnia industrial area. The fluxes and concentration profiles of the contaminants at Port Lambton have been modelled success fully using a simple transverse mixing model. A study on the chemical partitioning between the “dissolved” and “suspended sediment” phases shows that an important contaminant fraction is carried in the river by the suspended solids, particularly for lipophilie compounds such as HCB and OCS,

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A study on highly concentrated lactic acid and the synthesis of lactide from its solution

Journal of Chemical Research ◽

10.1177/17475198211021013 ◽

2021 ◽

pp. 174751982110210

Author(s):

Xiaolong Xu ◽

Lijuan Liu

Keyword(s):

Lactic Acid ◽

Acid Solution ◽

Concentration Distribution ◽

Raw Material ◽

High Concentration ◽

Composition Distribution ◽

Lactic Acid Solution ◽

H Nmr ◽

Back Titration ◽

Condensed Water

Lactic acid is an important platform compound used as raw material for the production of lactide and polylactic acid. However, its concentration and composition distribution are not as simple as those of common compounds. In this work, the mass concentration distribution of highly concentrated lactic acid is determined by back titration. The components of highly concentrated lactic acid, crude lactide, and polymer after the reaction are analyzed by HPLC. Different concentrations of lactic acid solution were prepared for the synthesis of lactide and its content in the product was determined by 1H NMR analysis. We found that lactide is more easily produced from high-concentration lactic acid solution with which the condensed water is easier to release. Hence, the removal of condensed water is crucial to the formation of lactide, although it is not directly formed by esterification of two molecules of lactic acid.

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Study on Dust Concentration Distribution in a Construction Tunnel

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/687/1/012162 ◽

2021 ◽

Vol 687 (1) ◽

pp. 012162

Author(s):

Fangfang Liu ◽

Xiyang Feng

Keyword(s):

Concentration Distribution ◽

Dust Concentration

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Box Experiment Study of Thermally Enhanced SVE for Benzene

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18084062 ◽

2021 ◽

Vol 18 (8) ◽

pp. 4062

Author(s):

Qixiang Zhang ◽

Qiyan Feng ◽

Xueqiang Zhu ◽

Mei Zhang ◽

Yanjun Wang ◽

...

Keyword(s):

Temperature Distribution ◽

Concentration Distribution ◽

Average Concentration ◽

Soil Gas ◽

Vapor Extraction ◽

Operation Process ◽

Repair Efficiency ◽

Benzene Concentration ◽

Benzene Content ◽

Peak Value

In order to describe the changes of soil temperature field, air flow field and remediation situation with time during the process of thermally enhanced SVE (soil vapor extraction), a remediation experiment of benzene contaminated soil with single extraction pipe was carried out in a box device. The results showed that the whole temperature of the system was raised to 80 °C in 4 h. 43% of benzene were removed in the first 2% of the extraction time. After 24 h, the repair efficiency was close to 100%. The device can efficiently remove benzene from soil. By continuously monitoring the parameters in the operation process of the system, the spatial distribution of temperature and soil gas pollutant concentration with time was plotted. It showed the benzene concentration distribution in the soil gas was more consistent with the temperature distribution before the start of ventilation, and the concentration of benzene in the soil gas dropped rapidly after ventilation, while the temperature distribution was almost unaffected. In the treatment of soil with a benzene content of 17.8 mg∙kg−1, when the soil gas benzene concentration is the highest at 180 min, the peak value is 11,200 mg∙m−3, and the average concentration is 7629.4 mg∙m−3.

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Numerical evaluation of contaminants mixing uniformity in a full-scale test chamber with mixing fan

Indoor and Built Environment ◽

10.1177/1420326x20979021 ◽

2020 ◽

pp. 1420326X2097902

Author(s):

Hai-Xia Xu ◽

Yu-Tong Mu ◽

Yin-Ping Zhang ◽

Wen-Quan Tao

Keyword(s):

Concentration Distribution ◽

Test Chamber ◽

Full Scale ◽

Numerical Results ◽

Test Method ◽

Test Accuracy ◽

Full Scale Test ◽

Concentration Region ◽

Airflow Field ◽

Scale Test

Most existing models and standards for volatile organic compounds emission assume that contaminants are uniform in the testing devices. In this study, a three-dimensional transient numerical model was proposed to simulate the mass transport process based on a full-scale test chamber with a mixing fan, and the airflow field and contaminants concentration distribution were obtained within the chamber under airtight and ventilated conditions. The model was validated by comparing the numerical results with experimental data. The numerical results show that the contaminant source position and the airflow field characteristics have significant impact on the contaminant mixing, and the fan rotation has an important role in accelerating mixing. In the initial mixing stage, the concentration distribution is obviously uneven; as the mixing progresses, it gradually reaches acceptable uniformity except for some sensitive regions, such as high concentration region at the injection point of the contaminants and low concentration region at the air inlet. To ensure test accuracy, the monitor should avoid above sensitive regions; and some special regions are recommended where contaminant concentration uniformity can be reached sooner. The ventilated chamber results indicate that the mixture of contaminants in the chamber is actually better than the results shown by conventional test method.

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MHD squeezed Darcy–Forchheimer nanofluid flow between two h–distance apart horizontal plates

Open Physics ◽

10.1515/phys-2020-0191 ◽

2020 ◽

Vol 18 (1) ◽

pp. 1100-1107

Author(s):

Ghulam Rasool ◽

Waqar A. Khan ◽

Sardar Muhammad Bilal ◽

Ilyas Khan

Keyword(s):

Heat Flux ◽

Fluid Flow ◽

Velocity Field ◽

Concentration Distribution ◽

Numerical Data ◽

Brownian Diffusion ◽

Nanofluid Flow ◽

Viscosity Parameter ◽

Thermal Distribution ◽

Factor Data

Abstract This research is mainly concerned with the characteristics of magnetohydrodynamics and Darcy–Forchheimer medium in nanofluid flow between two horizontal plates. A uniformly induced magnetic impact is involved at the direction normal to the lower plate. Darcy–Forchheimer medium is considered between the plates that allow the flow along horizontal axis with additional effects of porosity and friction. The features of Brownian diffusive motion and thermophoresis are disclosed. Governing problems are transformed into nonlinear ordinary problems using appropriate transformations. Numerical Runge–Kutta procedure is applied using MATLAB to solve the problems and acquire the data for velocity field, thermal distribution, and concentration distribution. Results have been plotted graphically. The outcomes indicate that higher viscosity results in decline in fluid flow. Thermal profile receives a decline for larger viscosity parameter; however, Brownian diffusion and thermophoresis appeared as enhancing factors for the said profile. Numerical data indicate that heat flux reduces for viscosity parameter. However, enhancement is observed in skin-friction for elevated values of porosity factor. Data of this paper are practically helpful in industrial and engineering applications of nanofluids.

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