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The effects of liquid-type additive, methoxynonafluorobutane, on the morphology, thermal conductivity, creep strain, and mechanical strength of polyurethane (PU) foams with an environment-friendly foaming agent, hyrdofluoroolefin, were investigated. The methoxynonafluorobutane under the trade name of NOVEC likely acted as a nucleating agent during the formation of PU foams. When NOVEC was added in the amount of 3 parts per hundred polyol by weight (php), the cell size of the foam was minimal, and the cell size distribution was relatively uniform. At the NOVEC content of 3.0 php, the thermal conductivity of the PU foams was also minimal. This decrease in thermal conductivity was due to the smaller cell size of the foams lowering their thermal conductivity. At 3.0 php NOVEC content, the creep strain of the PU foams was minimal being 0.29% at 1,000 h. At 3.0 php NOVEC, the estimated creep strain of the PU foam exhibited the lowest creep strain of 3.47% at 50 years. As a result, at 3.0 php NOVEC content, the cell wall was relatively less fractured, resulting in a small deformation of the PU foam. These results suggest that the main factors in improving the thermal insulation properties and stability of the PU foams are smaller cell size and narrow cell size distribution.

This study examined the effects of oxygen species on the unsteady-state oxidative coupling of methane (OCM) using a lengthy catalyst bed of Na2WO4/Mn/SiO2. The reaction conditions, including the methane-to-oxygen ratio, ratio of feed gas dilution by N2, quantity of catalyst, and feed flow rate were adjusted for the continuous flow fixed bed reaction system. While the O2 gas initiated methyl radical formation from methane, the surface lattice oxygen atoms improved the dehydrogenation of paraffins to olefins without significant activation of methane. The addition of CO2 as a mild oxidizing agent was also tested and slightly improved OCM selectivity with slightly lower methane conversion were observed.

SiO2@MnOx@Na2WO4@SiO2 core–shell catalysts were prepared and their fabrication was confirmed using transmission electron microscopy. The formation of Mn-based nanosheets on the silica spheres is important for the deposition of nanoscopic Na2WO4. The SiO2@MnOx@Na2WO4@SiO2 core–shell catalysts were used for the oxidative coupling of methane at a temperature of 700–800 °C at which the nanostructures were completely destroyed. Although the core–shell structures did not survive the high-temperature oxidative coupling of methane, the selective production of olefins and paraffins can be attributed to highly dispersed Na2WO4 derived from confined core–shell structures.

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE)/Nylon 66 blends have been considered as the potential heat resistant engineering plastics with high mechanical toughness and flame retardancy, suitable for high temperature applications. However, incompatibility between PPE and Nylon 66 and poor thermal stability of Nylon 66 degrade mechanical toughness and flame retardancy. In this work, for the first time, the PPE/Nylon 66 blends with high mechanical toughness and flame retardancy simultaneously have been prepared through newly synthesized compatibilizer of PPE grafted with fumaric acid (PPE-g-FA) and environmental-friendly non-halogen organic phosphinate flame retardant. The PPE/Nylon 66 blend achieved not only V0 grade flame retardancy with the help of improved fire resistance through the solid phase reaction of non-halogenic flame retardant, but also large impact strength larger than 10 kJ/m2 due to the strong compatibility of PPE-g-FA.

Ternary and quaternary liquid–liquid equilibria of three solutions (water + trimethylolpropane (TMP) + 2-ethylhexanol, water + TMP + octan-1-ol, and water + TMP + 2-ethylhexanol + formaldehyde) were studied at 298.15 K under atmospheric pressure. The consistency of the measured tie-line data was evaluated using the Othmer–Tobias, Bachman, and Hand equations. The properties of solvents, such as distribution constants, separation factors, and insolubilities, were examined in the ternary and quaternary liquid–liquid equilibrium systems. NRTL and UNIQUAC models were used to regress the ternary and quaternary systems and calculate binary interaction parameters. Finally, a comparison of experimental and calculated data, using the NRTL and UNIQUAC models, was performed.

The molasses embedded hybrid coal (Hybrid Coal by Korea Institute of Energy Research; HCK) was previously proposed as an attractive alternative to low-rank coals that tend to show low calorific values and high CO2 emissions. HCK was synthesized by mixing molasses with a low-rank coal to enhance its heating value. Nevertheless, food ethics regarding molasses additives still have impeded its commercial acceptance. In this study, we propose a glycerol (nonfood)-based coal upgrading process to improve the combustion kinetics and heating value of hybrid coal in comparison to the previous HCK. The process involves drying at 105 °C followed by torrefaction process at 250 °C. During torrefaction, the glycerol additive starts to evaporate at about 180 °C and then is almost vaporized out to the coal surface. To avoid glycerol loss, we employ sulfuric acid as a torrefaction catalyst to suppress glycerol evaporation. In comparison to the molasses yield of 65% after torrefaction in the previous HCK synthesis process, ...

To consider the effect of cross diffusion more rigorously, the onset and the growth of the gravitational instabilities in a Hele-Shaw cell saturated with ternary solution are analyzed by considering all cross diffusion coefficients. Through the asymptotic analysis, we identify the double-diffusive (DD)-, diffusive-layer convection (DLC)- and extended double diffusive (EDD)-type instability regimes. To support the asymptotic stability analysis, new linear stability equations are derived in the global domain and then transformed into the similar domain. In the similar domain, we prove that initially the system is unconditionally stable. For transient stability analysis, the linear stability equations are solved by employing quasi-steady state approximations (QSSA’s). To avoid the limit of the conventional QSSAz, we obtain the critical time for the onset of instability motion using the QSSA in the similar domain (QSSAζ).

Because 75% of the total cost of carbon capture and storage (CCS) arises from the separation of CO 2 from gas streams (Nsakala et al., 2001), the co-injection of CO 2 and impurities such as H 2 S, N 2 , and SO 2 is considered a cost-effective alternative to pure CO 2 geological sequestration. Here, the effect of the impurities on the onset of gravitational instability has been analyzed theoretically and numerically. Linear stability equations have been derived and solved analytically and numerically. Double diffusive effects make the system stable or unstable depending on the values of the diffusivity ratio, δ B , and buoyancy ratio, r β r C . In addition, using the Fourier spectral method, we have traced the temporal evolution of the gravitational fingers numerically. The shape and the growth history of the fingers are strongly dependent on the impurity content. The time-periodic oscillatory motions are not observed in the present linear and nonlinear analyses. For a given Rayleigh number, the dissolution of N 2 and H 2 S impurities makes the system stable, whereas dissolved SO 2 accelerates the onset of instability.

The application of biomass resources and sewage sludge is currently the most important issue in the field of coal combustion systems. The main drawback for operating a boiler system is its varied firing characteristics and low heating value. In this study, we have developed new synthetic fuels, namely hybrid sludge fuel (HSF), using coal and sewage sludge impregnated bioliquid (molasses) and evaluated their properties by comparison with conventional fuels. To prepare the HSF, it was treated in a carbonization system at 250 °C. Depending on the van Krevelen diagram, the fuel quality of HSF was superior to that of raw bioliquid and sewage sludge. In addition, its fuel characteristic was similar to sub-bituminous and bituminous coal. Thermogravimetric analysis (TGA) indicated only a single-stage combustion pattern for HSF during non-isothermal heating. To clarify the unburned carbon (UBC) content, an ultimate analysis was conducted. The amount of UBC of the HSF was much more than that of sewage sludge, but less than that of coal. To investigate the surface hydrophobicity of HSF, Fourier transform infrared spectroscopy (FT-IR) analysis and a moisture re-adsorption test were carried out. The HSF possessed high hydrophobicity and presented a low moisture re-adsorption rate compared to conventional fuels.

Decarboxylative coupling reactions of alkynyl carboxylic acids with aryl tosylates were developed in the presence of a palladium catalyst. Among the commercially available phosphine ligands, only 1-dicyclohexylphosphino-2-(di-tert–butylphosphino-ethyl)ferrocene (CyPF-tBu) showed good reactivity. The reaction took place smoothly and gave the decarboxylative coupled products in moderate to good yields. This demonstrates the excellent functional group tolerance toward alkyl, alkoxy, fluoro, thiophenyl, ester, and ketone groups. In addition, alkyl-substituted propiolic acids, such as octynoic and hexynoic acids, were coupled with phenyl tosylate to provide the desired products. We found that the electronic properties of the substituents on the phenyl ring in arylpropiolic acids are an important factor. The order of reactivity was found to be aryl iodide > aryl bromide > aryl tosylate > aryl chloride. However, aryl chloride-bearing electron-withdrawing groups showed higher reactivity than those bearing aryl tosylates.

In order to screen potential catalytic materials for synthesis and decomposition of ammonia, a series of ABO3 perovskite materials, Sr1–xYxTi1–yRuyO3−δ (x = 0, 0.08, and 0.16; y = 0, 0.04, 0.07, 0.12, 0.17, and 0.26) were synthesized and tested for ammonia dehydrogenation. The influence of A or B site substitution on the catalytic ammonia dehydrogenation activity was determined by varying the quantity of either A or B site cation, producing Sr1–xYxTi0.92Ru0.08O3−δ and Sr0.92Y0.08Ti1–yRuyO3−δ, respectively. Characterizations of the as-synthesized materials using different analytical techniques indicated that a new perovskite phase of SrRuO3 was produced upon addition of large amounts of Ru (≥12 mol %), and the surface Ru0 species were formed simultaneously to ultimately yield Ruz(surface)/Sr0.92Y0.08Ti1–yRuy–zO3−δ and/or Ruz–w(surface)/SrwRuwO3/Sr0.92–wY0.08Ti1–yRuy–zO3−δ. The newly generated surface Ru0 species at the perovskite surfaces accelerated ammonia dehydrogenation under different conditions, and ...

To improve cold gas efficiency of entrained-flow gasification, coal water slurry (CWS) as a fuel must have high heating value at low viscosity. Especially, considering unstable supply of bituminous coal, the preparation of CWS with high coal content from low-rank coal remains a challenging topic. In this study, we report a remarkable improvement in coal content of CWS at low viscosity (1000 cP) through torrefaction of low-rank coal. Compared to dried coal (moisture-free coal), the torrefaction of low-rank coal leads to an improvement in hydrophobic nature of coal surface and a decrease in coal porosity. The moisture readsorption ratio of the torrefied low-rank coal significantly decreases due to its high hydrophobic nature and low porosity. As a result, Kideco coal showed a 6% and 58.7% increase in the coal content and heating value of CWS after torrefaction at 300 °C in comparison to those of CWS made with dried coal. Ultimately, the torrefied coal-based CWS with enhanced coal content and heating value at low viscosity is expected to contribute to an increase in the efficiency of a gasifier and IGCC process.

The liquid–liquid equilibria of ternary systems composed of water, butane-2,3-diol, and alcohols such as 2-methylbutan-1-ol, 2-ethylbutan-1-ol, and 4-methylpentan-2-ol were studied at two different temperatures (298.15 and 308.15 K). The experimental tie-line data were compared with the compositional data predicted by the NRTL and UNIQUAC models. The distribution ratio and separation factors were calculated to evaluate the extraction efficiencies. Among the three different branched-chain alcohols selected as extractants, 2-methylbutan-1-ol, which has the shortest chain and branch, provided the highest distribution ratios of 0.55–0.67. The root-mean-square deviation (RMSD) values were calculated for each ternary system, and the average RMSD value was 0.0058, which assures good reliability.

A continuous flow reaction system in which a palladium magnetic catalyst was immobilized and vibrated by an alternating induced magnetic field was developed. The alternating electromagnetic field improved the mixing efficiency and catalytic activity for the palladium-catalyzed coupling reactions. This flow reaction system showed good product yields for various reactions such as Sonogashira, Heck, Suzuki, Stille, Hiyama and decarboxylative coupling reactions.

The temperature-induced phase behavior of a ternary system consisting of two fluorinated solvents and an organic solvent was studied. The solubility data and liquid–liquid equilibrium data for the following ternary systems were examined: (FC3283 + HFE7300 + hexane) at 273.15 K and 298.15 K, (FC3283 + HFE7500 + octane) at 298.15 K and 313.15 K, (FC72 + HFE7100 + acetonitrile) at 273.15 K and 298.15 K, and (FC72 + HFE7100 + ethyl acetate) at 273.15 K and 298.15 K. In addition, the experimental tie line data for eight ternary systems were correlated using the NRTL and UNIQUAC models, and the corresponding binary interaction parameters were determined.

We have performed NH3 plasma treatment of poly(ethylene-2,6-naphthalate) (PEN) surfaces with the purpose of incorporating nitrogen functional groups. X-Ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion spectroscopy (ToF-SIMS) were used to determine changes in the chemical structure of the PEN surfaces in response to different levels of plasma power. Plasma power had a significant impact on the type of nitrogen functional groups as well as the level of nitrogen incorporation. Considerable degradation and oxidation occurred with an excessive plasma power, rather than nitrogen incorporation. Optical emission spectroscopy (OES) confirmed that the type of chemical species present in the plasma discharge primarily determines the surface functionality with the plasma treatment. Partially decomposed ammonia species (NH and NH2) are considered to react with the PEN surface and form primarily amine groups. However, stable N2 species produced by bimolecular combination of fully decomposed atomic species led to the formation of imine groups via atomic rearrangement. Moreover, ion bombardment by N2+ species adversely affected the chemical structure of the surface, resulting in degradation of ester and carbon-carbon bonds and surface etching of carbon atoms. Open image in new window

The phase behavior of a temperature-dependent multicomponent system was investigated for ternary systems comprising a polar aprotic solvent, a solubility mediator, and aliphatic hydrocarbons such as octane, decane, or dodecane. The experimental tie-line composition and binodal composition were obtained for the ternary system of 4-methyl-1,3-dioxolan-2-one + 1,4-dimethylbenzene + octane, decane, or dodecane and the ternary system of acetonitrile + morpholine + octane, decane, or dodecane at two different temperatures, 298.15 K and 313.15 K. The distribution ratios of 1,4-dimethylbenzene and morpholine were determined, and the experimental tie-line results were adequately correlated using the nonrandom two-liquid (NRTL) activity coefficient model by utilizing the obtained binary interaction parameter.

Ultrahigh molecular weight bisphenol A polycarbonate (BPAPC) with nonlinear chain structures has been synthesized by solid-state polymerization in microlayers at 230 °C. It has been found that the ...

A fluorous biphasic system consists of a fluorinated solvent and an organic solvent. The mutual solubility data of fluorous biphasic systems were analyzed for common organic solvents such as benzene, toluene, and xylene with perfluamine. Fluorous/organic amphiphilic ether solvents such as HFE7300 and HFE7500 were added to the fluorous biphasic system. The equilibrium tie lines for ternary systems were determined at two different temperatures, and the equilibrium data sets were correlated with the nonrandom two-liquid and universal quasichemical models.

A number of ternary systems with two fluorinated solvent mixtures and tetrahydrofuran (THF) were studied. The perfluorinated solvent phase consisted of perfluorohexane (FC72) or perfluamine (FC3283) with hydrofluoroether (HFE7100, HFE7300, and HFE7500). Hydrofluoroether was added to perfluorohexane or perfluamine to tune the fluorophilicity of the fluorous phase. The temperature dependence of the liquid–liquid equilibrium was investigated at two different temperatures, 298.15 K and 273.15 K. The immiscibility region at 273.15 K was larger than that at 298.15 K. The NRTL and UNIQUAC models yielded good correlation for the 10 ternary systems, including FC72 + HFE7100 + THF, FC72 + HFE7300 + THF, FC72 + HFE7500 + THF, FC3283 + HFE7300 + THF, and FC3283 + HFE7500 + THF.

Equilibrium tie-line data were determined for a fluorous biphasic systems at 298.15 K. Two phase mixtures were used, consisting of a perfluorinated solvent phase using a mixture of two fluorinated solvents (methyl nonafluorobutyl ether and perfluorohexane) as well as an organic solvent phase in which the organic solvents studied were toluene, 1,4-dioxane, and dimethylformamide, respectively. Nonrandom two liquid models applied to the four ternary systems produced interaction parameters that were well-correlated with the equilibrium composition. These parameters enabled the prediction of liquid–liquid equilibrium systems containing methyl nonafluorobutyl ether and perfluorohexane. The ability to manipulate fluorous biphasic systems composed of perfluorohexane and an organic solvent with the addition of methyl nonafluorobutyl ether was examined.

Submicron size polyethylene particles were prepared by a thermally induced phase separation process in a split-and-recombine type micromixer. Process parameters such as polyethylene concentration, ratio of nonsolvent to solvent, initial temperature of the nonsolvent and total flow rate play important roles in controlling particle size. The results show that spherical polyethylene particles were obtained with an average diameter ranging from 0.22 μm to 0.52 μm. The continuous flow micromixer system prevented coagulation, therefore the size of the prepared polyethylene particles can be predicted using the continuous flow micromixer system.

The production of cellobiose dehydrogenase (CDH) and β-glucosidase by Phanerochaete chrysosporium ATCC 32629 was assessed during submerged fermentation. The maximum concentrations of CDH and β-glucosidase were obtained using rice straw as the carbon source. Organic nitrogen sources were more effective in enzyme production than inorganic nitrogen sources. Corn steep liquor (CSL) for CDH production and soy bean meal (SBM) for β-glucosidase production were the most appropriate organic nitrogen sources. Using optimum medium obtained by response surface methodology (RSM), the maximum concentrations of CDH and β-glucosidase achieved in the stirred-tank reactor (STR) were 204 U/L and 140 U/L, respectively. CDH productivity (22.7 U/L·day) was the highest at 9 days.

Cellobiose dehydrogenase(CDH) as a hemoflavoenzyme is secreted out of cell in the cellulose degrada- tion. As CDH strongly bound to amorphous cellulose, it helps cellulose hydrolysis by cellulase. CDH may have an important role of saccharification process for bioethanol production. In this study, Phanerochaete chrysosporium ATCC 32629 was selected for the production of CDH among other strains tested. The optimal temperature and pH of CDH pro- duced by P. chrysosporium ATCC 32629 were 55 o C and 4, respectively. To improve the activity of CDH, the mutation of P. chrysosporium was performed using proton beam that has high energy level partially. As a result, P. chrysosporium mutant with the high activity was selected at 1.2 kGy in a range of 99.9% lethal rate. The CDH and β-glucosidase activ- ities of mutant were 1.4 fold and 20 fold higher than those of wild strain. Therefore, P. chrysosporium mutant with the high activities of CDH and β-glucosidase was obtained from mutation by proton beam irradiation.

Sodium borohydride has received much attention from fuel cell developers due to its high hydrogen storage capacity. In this study, organic acid solutions such as malic, citric, acetic acids were successfully utilized to accelerate and control hydrogen generation from stabilized sodium borohydride solutions. The generated hydrogen by malic acid was then continuously supplied to a PEMFC single cell. A power density of 168 mW cm −2 was achieved with a hydrogen flow rate of 0.050 L min −1 that was generated by adding 10 wt% aqueous malic acid to the stabilized sodium borohydride solution at an air flow rate of 0.11 L min −1 without humidification. Further increase of power density to 366 mW cm −2 is practicable by maintaining a precise hydrogen flow rate of 0.3 L min −1 . The current study focuses on the development of an instant hydrogen generation method for micro fuel cell applications. We successfully demonstrated that fast and direct generation of hydrogen could be achieved from stabilized borohydride using inexpensive organic acid solutions rather than expensive metal catalysts and a PEMFC single cell could be operated by generated hydrogen.

Phase diagrams of mixtures consisting of (cyclohexane + cyclohexanone + dimethyl sulfoxide) and (cyclohexane + cyclohexanol + dimethyl sulfoxide) were obtained at a temperature of 303.2 K. Nonrandom two-liquid and UNIQUAC models applied to both ternary systems produced interaction parameters that were well-correlated with the equilibrium compositions. These parameters enable the prediction of (liquid + liquid) equilibrium mixtures with either cyclohexanone or cyclohexanol.

The Wilson-plot method has been used for mass transfer correlations and proved to be suitable for systems operating in steady-state conditions and where the only variable is the fluid velocity. A statistically robust Wilson-plot methodology is suggested and proved to be available to calculate the mass transfer coefficients of hollow fiber membranes. This method combines the linear regression analysis and objective function of F-ratios in the analysis-of-variance (ANOVA) table, or coefficient of determination, R2. For the objective function of the optimization problem to find the exponent of velocity, the F-ratio is more suitable than the coefficient of determination. With moderate errors in the measured data, membrane mass transfer coefficients are estimated with small confidence intervals.

The liquid–liquid equilibria for the water + n-pentanoic acid + n-heptane system and the water + n-pentanoic acid + dichloromethane system were determined at 298.2 K. The NRTL and UNIQUAC models were applied to both ternary systems. The interaction parameters obtained from the NRTL model correlated with the equilibrium compositions better than those from the UNIQUAC model.

Two different types of split–recombine micromixers have been tested for a gas/liquid dispersion. Mixing performances of two micromixers have been compared in terms of a mixing efficiency. The effects of liquid flow rates, the ratio of gas/liquid flow rate, bubble sizes, and bubble size distributions have been investigated. The sequential split micromixer and the caterpillar micromixer showed a consistent mixing performance at various flow rates. The sequential split micromixer has shown the smaller and narrower bubble size distribution than that of the caterpillar micromixer at a higher flow rate of 1.8 L/h.

A two-stage continuous microreactor system was use to synthesize the materials for an organic light emitting diode. The split and recombine type of micromixers were suitable for the two-stage reaction including lithium-bromo exchange reaction. The two-stage synthesis was carried out under non-cryogenic conditions by taking full advantage of microstructured reaction systems. In a first stage, the unstable intermediate, naphthyl lithium was synthesized with maximum yield and consumed immediately in the second stage micromixer. The naphthyl-substituted anthracene was obtained with 97% purity.

A high pressure microreaction system was applied to synthesize 1-methyl-1-cyclopenten-3-one. Design of experiment was used to identify the most dominant factors and the interactions from the microreaction system of an intramolecular aldol condensation reaction of 2,6-hexanedione. The response surface methodology coupled with Box–Behnken design was applied to obtain the optimum process conditions. The feed flow rates or residence time were identified as significant variables of this microreaction system. 1-methyl-1-cyclopenten-3-one was isolated in 60% yield after purification with 99.9% purity within the optimum operation ranges determined by design of experiment method.

Characteristics of hydrogen evolution from non-stabilized and alkali-stabilized sodium borohydride solutions were systematically studied in order to understand the fuel storage features of borohydride in fuel cell applications. The effects of the sodium borohydride concentration, the temperature of the hydrolysis reaction, the sodium metaborate concentration, and the continuous temperature control for alkali-stabilized sodium borohydride solutions on the hydrogen generation and yield were investigated. Temperature variation was the major parameter that affected the stability of sodium borohydride solutions with and without stabilizing agents during hydrogen storage.

The problem of determining the shell-side Taylor dispersion coefficient for a shell-and-tube configuration is examined in detail for square and hexagonal arrays of tubes for the case when the shell side flow is laminar and parallel to the tubes. A multipole expansion method is employed to determine fluid velocity and concentration field for the fluid on the shell side. The numerical results for the shell side Taylor dispersion coefficient are compared with those by a cell theory. The cell theory agrees well with the numerical results at small area fractions and gives better estimates for hexagonal arrays. Finally, we present formulas for determining Taylor dispersion coefficient for the periodic arrays.

A mixing device composed of a micron scale flow channel was applied as a continuous reactor to control exothermic reaction heat and to increase the product yield, in a synthesis of a pharmaceutical intermediate of quinolone antibiotics. The model reaction featured a fast reaction rate, high heat generation, and impurity formation due to a prolonged contact time between reactants and products. Using the micromixer reactor, the reaction heat was efficiently removed so that virtually no impurities were produced during the reaction. A product yield comparable to the theoretical value was achieved in a single micromixer unit. Optimum operating conditions were acquired from a statistical method by using factorial design, which was also verified by a CFD calculation.

Ethylene-norbornene copolymerization was investigated by using metallocene catalysts, [2,2′-methylenebis( 1,3-dimethylcyclopentadienyl)]zirconium dichloride(2,2′-CH2 (1,3-Me2Cp)2ZrCl2, Catalyst A) and racemicethylenebis( indenly)zirconium dichloride (rac-Et(Ind)2 ZrCl2, Catalyst B), in the presence of methylaluminoxane as a cocatalyst. The influences of different process parameters such as polymerization temperature and ethylene pressure were studied by using a 56 wt% norbornene solution in toluene. The results show that Catalyst A has a higher activity in copolymerization than Catalyst B. Catalyst A also has a superior norbornene insertion performance to Catalyst B, resulting in polymers with higher glass transition temperatures, by approximately 70 ‡C, at similar polymerization conditions, indicative of a great commercial potential of Catalyst A.

Although reliability analyses have been used to improve the reliability of industrial systems, generic reliability data from publications, such as component failure intensities and repair times, are used to calculate reliability measures instead of the real reliability data collected from the plant. One reason is that the repair history of the components is not well managed in the plant. In this work, the effect of extreme reliability parameter values on system reliability and unavailability is studied. To do this, importance and uncertainty analysis of the components of flue gas scrubber systems is carried out, and results calculated with the extreme reliability parameter values are compared with those with the mean reliability values of the systems. The different reliability parameter values can give us totally different ranks of the components critical to the reliability of the representative scrubber system. Consequently, the effort to establish a reliable database is emphasized to perform accurate reliability analysis of the system.

Experimental and theoretical modeling studies are presented on the forced gas sweeping process for the continuous melt polycondensation of bisphenol A polycarbonate. In this process, unlike in the conventional high-vacuum melt polycondensation (transesterification) process, the condensation byproduct (phenol) is removed from a highly viscous polymer melt by forcing inert gas bubbles to flow directly through the polymer melt phase. As the gas bubbles rise in the polymer melt phase, dissolved phenol molecules diffuse to the bubbles and are removed from the polymer melt, and the polymer molecular weight increases. In this study, the feasibility of continuous reactor operation is investigated using a continuous rotating-disk reactor at 260−300 °C and ambient pressure. With a low-molecular-weight polycarbonate prepolymer (Mn = 5050) as the feed, polycarbonate of molecular weight up to 20 000 has been obtained at steady state. To investigate the effect of reactor operating conditions on the polymer molecular we...

Operating strategies and optimum feed tray locations were studied in a typical fractionation process of a BTX plant in Korea in order to reduce energy consumption. Control systems with fixed V/F or R/F ratios could be recommended for various feed compositions. By choosing the optimum feed tray location for the columns, about 16% of energy consumption could be reduced.

The heat transfer effect of an inert gas on a multi-tubular reactor for a partial oxidation reaction has been determined. The model reaction system in the study was partial oxidation of propylene to acrolein. Both theoretical modeling and experimental studies have been performed to determine the heat transfer effect of inert gas on the system. Among many inert gases, CO2 was selected and tested as a diluent gas for the partial oxidation of propylene to acrolein system instead of conventionally used N2. The productivity increase through changing the inert gas from N2 to CO2 was possible due to the heat transfer capability of CO2. In this study, by replacing the inert gas from N2 to CO2, productivity increased up to 14%.

Experimental and modeling studies are presented on the synthesis of bisphenol A polycarbonate at ambient pressure by a novel forced gas sweeping process. Unlike in the conventional high-vacuum melt...

The liquid−liquid equilibria for water + 3-methyl-2-cyclopentenone + ethyl acetate and water + 3-methyl-2-cyclopentenone + methyl tert-butyl ether system were determined at 293.2 K. The NRTL and UNIQUAC models were applied to both ternary systems. The interaction parameters obtained from both models successfully correlated the equilibrium compositions.

Liquid−liquid equilibria for nonane + dimethyl carbonate + methanol and decane + dimethyl carbonate + methanol were determined at 298.15 K. The NRTL and UNIQUAC models were used to correlate both ternary systems. The interaction parameters obtained from both models successfully correlated the equilibrium compositions.

The liquid−liquid equilibrium for the 1-pentanol + tris(hydroxymethyl)propane + water and 1-hexanol + tris(hydroxymethyl)propane + water systems were determined at 293.15 and 313.15 K. The NRTL and UNIQUAC models were applied to both ternary systems. The interaction parameters obtained from both models successfully correlated the equilibrium compositions.