• Title/Summary/Keyword: Partiton coefficient

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A Computational Study of Natural Convection in Vertical Rectangular Enclosures with Partiton Plates of Finite Thermal Conductivity (유한열전도율(有限熱傳導率)의 격판(隔板)을 갖는 수직구형(垂直矩形) 밀폐공간(密閉空間)에서의 자연대류(自然對流)에 관(關)한 수치적(數値的) 연구(硏究))

  • Park, Man-Heung;Lee, Jae-Heon
    • Solar Energy
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    • v.2 no.1
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    • pp.1-8
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    • 1982
  • A theoretical study by numerical method has been performed on the natural convection of an air contained in enclosures. The enclosures have rectangular cross section with one vertical wall heated and the other cooled, and with two horizontal partition plates of finite thermal conductivity. Steady two-dimensional flow was assumed. The computation was executed by means of the Implicit Alternating Direction (I.A.D) finite-difference method. Two partition plates of Aluminium whose thickness were 0.05mm was employed in computation. Isothemals, streamlines, local Nusselt numbers and mean Nusselt numbers were obtained for various Grashof numbers and aspect ratio and these results were compared with those in the case of the enclosure with two horizontal insulated plates. From the present results, the heat transfer in the case of partition plates was greater than that in the case of insulation. This study suggests a method to measure the overall heat-transfer of coefficient in double walls which supported by partition plates for insulative construction.

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The Characteristics of Soil Organic Matter

  • You Sun-Jae;Kim Jong-gu;Cho Eun-Il
    • Journal of Environmental Science International
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    • v.15 no.1
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    • pp.1-7
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    • 2006
  • The purpose of this study is to illustrate the characteristics of soil organic matter (SOM) and partition coefficient $(K_{DOC})$. Humic substances (HS) from eight soils of varying properties were extracted by two different methods. The dissolved organic carbon (DOC) concentration was stabilized in 22hrs. The ratio of UV absorbance at 465nm and 665nm (E4/E6 ratio) for HS were similar pattern for 8 soils. The extraction with increasing pH increased dissolution of SON. The ratio of organic carbon (OC) associated with HA and FA (the HA:FA ratio) was varied widely in accordance with the soils and was highly correlated to OC $content(\%)$ of the soils. in modeling metal speciation in soils and soil solutions, assumptions that all DOC in soil solution is associated with FA and that HA:FA ratio in SOM is constant have been made. The results of this study indicate that the validity of these assumptions is questionable. By sequential pH extraction, the $K_{DOC}$ showed in a linear correlation with pH.

Slow-Stirring Methods for Determining the n-Octanol/Water Partition Coefficient(Pow) of Highly Hydrophobic Chemicals (극소수성 물질들에 대한 Slow-Stirring방법에 의한 옥탄올/물 분배계수 측정)

  • Chang Hee Ra;Lee Bong Jae;Kim Kyun;Kim Yong Hwa
    • Environmental Analysis Health and Toxicology
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    • v.20 no.4 s.51
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    • pp.351-358
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    • 2005
  • The n -octanol/water partition coefficient (Pow) is one of the most important parameters employed for estimating a chemiral's environmental fate and toxicity. The shake-flask method, one direct experimental method, i.1 prone to experimental artifacts for highly hydrophobic compounds. Thus, a valid method for direct determination of the Pow of highly hydrophobic compounds is needed. The slow -stirring method has been demonstrated to provide reliable log Pow data to log Pow greater than 5. This study was performed to evaluate the accuracy of slow- stirring experiment for determination of log Pow, particularly for highly hydrophobic compounds. 1, 2, 3, 4-tetrachlorobenzene, hexachlorobezene, 2, 2', 3, 3', 5, 5', 6, 6'-octachlorobiphenyl, decachlorobiphenyl, and p, p'-DDT (4.5$\times$0.02, 5.41$\times$0.06, 7.26$\times$0.04, 7.87$\times$0.10, and 6.03$\times$0.06, respectively. The octanol/water partition coefficient by the slow-stirring method were very similar to the literature values. These results indicate that the slow- stirring method allows for reliable determination of log Pow of highly hydrophobic chemicals.

Adsorption and Oxidation of Polychlorinated Phenols onto Transition Metal Oxides (I). Adsorption Characteristics and Reductive Dissolution of ${\sigma}-MnO_2$(s) (전이금속산화물에 대한 다염소치환페놀류의 흡착과 산화 (제 1 보). ${\sigma}-MnO_2$(s)의 흡착특성과 환원성 용해)

  • Jong Hoon Yun;Jong Wan Lim;Heung Lark Lee;Sang Oh Oh;Sun Haing Lee
    • Journal of the Korean Chemical Society
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    • v.35 no.3
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    • pp.226-232
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    • 1991
  • Adsorption and oxidation of polychlorinated phenols by suspended ${\sigma}-MnO_2$ in aqueous solution have been studied. Of the proposed mechanism, adsorption reaction of chlorophenols onto ${\sigma}-MnO_2$(s) depended upon the pH of the solution and the concentration of chlorophenol. Adsorption isotherms showed a reasonably good fit to the Langmuir isotherm. From the pH dependence of adsorption partition coefficient and the linear relationship between octanol-water partition coefficient and adsorption partiton coefficient of chlorophenol, it is estimated that adsorption is dominated by its hydrophobicity. The rate of electron transfer reaction evaluated from the rate of reductive dissolution of ${\sigma}-MnO_2$(s) depended linearly upon the concentration of chlorophenol and the pH of medium. Observed rate constants ($K_0$) of the meta-substituted chlorophenol were lower than that of the ortho-or para-chlorophenol because of resonance effect of chlorophenoxy radical. It is indicated that this radical is produced in the adsorption process and the electron transfer reaction is rate determining.

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