1,721,034 research outputs found
Influence of ceramic support on pervaporation characteristics of IPA water mixtures using PDMS ceramic composite membrane
No full textThe pervaporation of IPA(isopropanol)-water mixture was carried out by using PDMS (poly(dimethylsiloxane))/ceramic composite membrane. In the pervaporation using homogeneous PDMS membrane without ceramic support selectivities of IPA were inversely proportional to operating temperature. However, selectivities of IPA in the pervaporation using PDMS/ceramic composite membrane increased with operating temperature in the range from 0 to 20 wt% of IPA in feed mixture. In this composition range, the effect of capillary condensation of water in ceramic pores on selectivities is more dominant than that of plasticization of PDMS by IPA. In more than 20 wt% IPA in feed mixtures the plasticization of PDMS by TPA in feed is dominant, thereby the selectivities of IPA is inversely proportional to the operating temperature. These coupling effects containing capillary condensation and plasticizing effect were investigated by measuring permeation ratio of each component. In the case of PDMS/ceramic composite membrane, fluctuation of permeation ratio with operating temperature was observed around 0-10% of IPA in feed mixture. It is explained by the blockage in ceramic pore due to capillary condensation of water. No severe fluctuation was observed at any feed concentration range by using homogeneous PDMS membrane without ceramic support. (C) 1999 Elsevier Science B.V. All rights reserved
Inverse analysis for estimating the unsteady inlet temperature distribution for two-phase laminar flow in a channel
No full textAn inverse thermal problem was considered for two-phase laminar flow in a parallel plate duct. The inlet temperature, which varies temporally as well as spatially, was estimated when measured temperatures were available at downstream of the duct. In the present study, the problem is solved through a minimization of an objective function by using two regularization methods, i.e., the iterative conjugate gradient method (CGM) and the Tikhonov regularization method (TRM). The effects of the functional form of inlet temperature profile, the number of the measurement points and the measurement errors are investigated and discussed. The computational accuracy and efficiency of these two regularization method are compared and discussed. (c) 2005 Elsevier Ltd. All rights reserved.The present work was supported by the Combustion Engineering Research Center at the Department of Mechanical Engineering, KAIST, which is funded by the Korea Science and Engineering Foundation
Reactive extraction of succinic acid with tripropylamine (TPA) in various diluents
No full textSuccinic acid is of interest as the raw material of polysuccinate which is a biodegradable polymer. The tripropylamine (TPA) was used as the extraction agent for the reactive extraction of succinic acid in various alcohol diluents. Equilibrium and loading data for various active diluents were obtained at various TPA concentrations. At the same TPA concentration the extractabilities of TPA increased as the number of carbon in alcohols decreased. It was explained by decreasing solubility of acid-amine complex due to decreasing polarity with increasing the number of carbon in alcohols. The type of succinic acid-amine-diluent complex was predicted by the value of loading with various concentration of TPA/various alcohols
Extraction of succinic acid with 1-octanol/n-heptane solutions of mixed tertiary amine
No full textThe reactive extraction of succinic acid was carried out by mixed tertiary amine which consisted of tripropylamine (TPA) and trioctylamine (TOA) as the extraction agent in 1-octanol/n-heptane diluent. Maximum distribution coefficient was obtained at 8:2 weight ratio of TPA/TOA. At this ratio, its extraction efficiency is above 90% at the 3.9 wt.% of succinic acid in aqueous solution. Furthermore, the prevention of the third phase formation made the phase separation between organic phase and aqueous phase easy
Inverse radiation problem in determination of the inlet temperature profile for two-phase laminar flow in a channel
No full textAn inverse thermal problem is considered for two-phase laminar flow in a parallel-plate duct where there is conductive, convective and radiative heat transfer involved. The inlet temperature distribution is estimated when only measured gas temperatures are available at downstream of the duct. The inverse problem is solved through a minimization of an objective function by using two regularization methods, i.e., the iterative conjugate gradient method ( CGM) and the Tikhonov regularization method ( TRM). The effects of the functional form of inlet temperature profile, the number of the measurement points, and the measurement errors are investigated and discussed. The computational accuracy and efficiency of these two regularization methods are compared and discussed. Both CGM and TRM are found to work well for finding the inlet temperature, even when radiation is involved. However, usually the TRM requires a longer computational time than the conjugate gradient method because of nonlinearity in estimating the sensitivity coefficient
Equilibrium studies on reactive extraction of succinic acid from aqueous solutions with tertiary amines
No full textReactive extraction of succinic acid from aqueous solutions with various tertiary amines dissolved in 1-octanol and n-heptane has been studied as a function of the acid concentration and the chain length of tertiary amine. When 1-octanol was used as diluent, the extractability of the tertiary amine was proportional to the chain length of tertiary amine at the same concentration of amines. The loading values were also proportional to the chain length of tertiary amine. However, when n-heptane was used as diluent, the extractability and loading values of the tertiary amine were inversely proportional to the chain length of amines. It was due to the aggregate formation of the acid-amine complex
Effect of pH on the extraction characteristics of carboxylic acids from aqueous solutions with trioctylamine in 1-octanol
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Separation characteristics of lactic acid in reactive extraction and stripping
No full textLactic acid has recently been drawing much interest as a raw material for biodegradable polymer. Various extractants for lactic acid separation were tested and TOA (trioctylamine) was found the most effective one. Lactic acid was separated by reactive extraction with TOA dissolved in various diluents. The effect of temperature on the extraction efficiency was smaller than that of composition for the system studied in this work
Effect of salts on the extraction characteristics of succinic acid by predispersed solvent extraction
No full textPredispersed solvent extraction (PDSE) of succinic acid with Tri-n-octylamine (TOA) dissolved in 1-octanol from aqueous solutions of 50 g/L succinic acid was examined. It was found that the equilibrium data in PDSE was equal to that in conventional solvent extraction in spite of the lack of mechanical mixing in PDSE. The influence of salts on succinic acid extraction and the stability of colloidal liquid aphrons (CLAs) were also investigated. Results indicated that in the presence of sodium chloride, less succinic acid was extracted by CLAs and the stability of CLAs decreased. However, the stability of CLAs was sufficient to make PDSE practically applicable to real fermentation broth, considering the concentration range of salts in the fermentation process for succinic acid
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