The evaporation phenomenon of metals is simulated by using the lattice Boltzmann method (LBM). It is the objective to obtain the evaporation rate of metals in an inert gas in high temperature. The relaxation time for the BGK type relaxation of the LBM is derived microscopically. The evaporation rate is arranged with the reduced pressure, the ratio of saturated vapor pressure and total pressure, and the Knudsen number. The dependence of the evaporation rate on pressure of surrounding gas is compared with reported experimental results and validity of the simulation is confirmed. The potential model of metal atoms at a collision and the discrete velocity model of the LBM are evaluated and the simulated evaporation rate hardly depends on them. The evaporation rates at various kinds of surrounding gas and evaporating metal gas are calculated, and the decrease of the evaporation rate depends on momentum transfer in collision, not on collision cross sections.

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A realistic non-spherical model for bubble formation in a co-flowing liquid is presented. In the model, an interfacial element approach is applied to describe the dynamics of bubble formation. The effect of flowing liquid velocity is modeled by a combination of the bubble axis translation and liquid pressure analysis of each interfacial element. The bubble shapes during formation are predicted reasonably well by the present model. The effects of liquid velocity, gas flow rate, nozzle radius and gas chamber volume on the bubble growth rates are studied. The model predictions are compared with the experimental data in literature and show good agreement.

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In this study, the controlled or uncontrolled release of a vapor-liquid mixture during the blowdown of a pipeline carrying a flashing liquid has been numerically simulated. The liquid may be pure such as propane or a mixture of two or more components, such as liquefied petroleum gas (LPG). With the help of a mathematical model, transient pressure and temperature profiles, quality of a 2-phase vapor-liquid mixture and the amount of the liquid remaining in the pipe during a typical blowdown are predicted. The theoretical analysis based on the assumption of a homogeneous two-phase flow (no slip condition between phases) allows for external heat transfer from the ambient to the liquid stored in the pipe. The simulation results show that the sudden depressurization of the liquid stored under supersaturated conditions may result in rapid cooling of the liquid possibly to the temperature below the ductile brittle transition temperature (DBTT) of the material of construction of the pipe. This may be hazardous as the pipe may rupture at weak locations along the length. The simulation results also show significant effects of ambient temperature, use of a low vapor pressure liquid as an additive, and pipewall roughness on total blowdown time of a long pipe. The present study is important from the point-of-view of maintenance and operation of pipelines carrying flashing liquids, especially in chemical industries and offshore oil and gas exploration operations. The model simulation results have been validated, wherever possible, with those published in literature.

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Research has been carried out to understand the mechanisms under which coke formation occurs and to search for solutions to reduce or eliminate coke deposition. Significant efforts have been exerted over the past twenty years in developing coke-inhibiting methods. Coke inhibitors, i.e., chemical additives, or special coating of metal surfaces which suppress coke formation. Coke inhibitors/surface coating work by passivating catalytically active metal sites through chemical bonding interactions, and/or forming a thin layer to physically isolate the metal sites from coke precursors in a process stream, and/or interfering with those radical reactions leading to coke formation by blocking active radical sites on surfaces. This review paper investigates the effect of the most important methods such as new chemical additives, tube material construction, pretreatment of surface on the coke formation of pyrolysis furnaces.

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To investigate the interaction between molecules incorporated into hydrogels and gel framework of hydrogels, SiO₂ and TiO₂ hydrogels containing a surfactant or Ru(bpy)₃²⁺ are prepared by a sol-gel method. For the hydrogels into which a surfactant is incorporated, the interaction is investigated through aggregation behavior of the surfactant. When the surfactant has no charge or the same charge as that of gel framework, the interaction is weak and aggregation of the surfactant occurs. When Ru(bpy)₃²⁺ is incorporated, it is absorbed strongly by SiO₂ gel framework but not absorbed by TiO₂ one. The interaction between Ru(bpy)₃²⁺ and SiO₂ gel framework is so strong as to change photochemical properties of Ru(bpy)₃²⁺ greatly.

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In order to produce a highly oriented diamond layer on a silicon (100) substrate, reaction conditions should be controlled so as to achieve an initial selective growth on the (111) face, followed by the (100) face. In the present study, cubo-octahedral diamond crystals were formed by the microwave plasma-assisted chemical vapor deposition of methane and hydrogen on a silicon (100) wafer. Trimethylboron and dimethylsulfur as the boron or sulfur sources, respectively, were added to the gas phase and diamond was homoepitaxially deposited on the {100} and {111} of the crystals. The growth rate determined from geometrical changes in the crystals, was affected by the type of diamond faces used, the boron to carbon (B/C) and sulfur to carbon (S/C) ratios in the gas phase, the methane concentration, and the substrate temperature. The growth rate decreased with increasing B/C and S/C ratios, but the relative growth rate of [100] to [111] remained nearly independent of the dopant concentration. The [111] preferred growth was realized under lower methane concentrations and higher substrate temperatures.

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Solubilization of a calix[4]arene carboxylic acid derivative in an aliphatic organic solvent was accomplished by utilizing a reverse micellar solution. The reverse micellar solution was prepared by cationic cetyltrimethyl ammonium bromide (CTAB) or anionic bis-2-ethylhexyl sulfosuccinate (AOT). Both reverse micellar solutions facilitate the solubilization of the calix[4]arene carboxylic acid derivative in isooctane. The concentration of calix[4]arene solubilized in the reverse micelles increases with an increase of surfactant concentration. The water content in the reverse micelles (W₀ = [H₂O]/[surfactant]) also affects the solubilization behavior of calix[4]arene. The optimum water content existed for the formation of the reverse micelles and the value was around 20. The extraction performance of calix[4]arene solubilized was investigated for yttrium (III) in isooctane. The extraction ability of calix[4]arene was enhanced by solubilizing in the anionic reverse micellar solution.

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A single stage preparation method, based on soapfree emulsion polymerization with an amphoteric initiator, is proposed for producing monodisperse, micron-sized polymer particles. The aggregation and stability of polymer particles, which have ionizable groups arising from initiator radicals, can be controlled by adjusting the pH of the reaction system. The present method was examined in the polymerizations of styrene employing an amphoteric initiator, 2, 2′-azobis [N-(2-carboxyethyl)-2-2-methylpropionamidine], and a pH buffer, NH₃/NH₄Cl. In the polymerizations, pH was ranged from 8.1 to 8.8 and monomer concentration from 1.1 to 2.2 mol/dm³ H₂O for an initiator concentration of 8 mmol/dm³ H₂O at 65°C. Selection of the reaction conditions could produce polymer particles with an average diameter of 2.5 μm and a coefficient of variation of particle size distribution as small as 1.3%.

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Batch processes are widely used in producing high-value chemical products for its good flexibility. The problem of short-term scheduling of batch plants is to determine the optimal utilization of available resources over a given time horizon. Models of most previous works in this domain rely on the definition of time slots or time events so that they involve many binary variables and constraints. In this paper, a new MILP model for scheduling of both multi-product and multi-purpose batch plants with unit-depended changeovers is introduced. Problems are described based on the concept of task in order to deal with complex instances. The proposed formulation uses a continuous time domain representation that does not rely on the definition of time slots or time events. Binary variables for sequencing are defined to indicate whether one task is prior to another in the processing sequence without concerning their accurate position. The model is also simplified by considering the specialty of symmetrical and complemental feature of the binary variables. In a result the number of both binary variables and constraints has been reduced significantly. Moreover, different heuristic rules for preordering can be flexibly embedded into the new model and directly assign the value of binary variables. Therefore much CPU time is saved even maybe without loss of rigorous optimality. Several case studies are presented that illustrate the efficiency of the new model. Comparisons with some previous works are also provided.

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Taylor-eddy and paddle type apparatus were applied for refolding of lysozyme in a continuous system. The number of theoretical mixing stages was measured for both the apparatus and the effect of flow rate and mixing rate on the axial dispersion of solutions flowing inside of a ceramic membrane tube were investigated. Refolding at different concentrations of lysozyme was performed by addition of denatured lysozyme into refolding buffers flowing through the inside of the tube. For studying the effect of addition, different addition methods of denatured lysozyme into refolding buffer were devised by using ceramic membranes, from the total surface of the membrane tube and partially upside ceramic membrane. Comparing the efficiencies of continuous refolding with those of batch method, higher refolding efficiencies were obtained in the continuous system at the same concentrations of lysozyme and urea. Therefore, by combining the merits of the fed-batch method and continuous system, the refolding efficiency can be improved as well as throughput of refolding process.

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A reversible reaction process can be used in a chemical heat pump for cooling or heating purposes, depending on the thermodynamic conditions in the reactor. In this work an experimental chemical heat pump with a reversible reaction of calcium oxide and water is discussed. The intention of the research work was to intensify heat and mass transfer in the reactor bed during the hydration phase at low operating pressure, which would enable the use of the reaction device as a part of high-efficient cascading sorption cooling device. Due to a low thermal conductivity of the reactive salts, the expanded graphite is used as a binding material in the reactor bed. To intensify mass transport to reaction sites and to shorten the hydration reaction the reactor bed is prepared with additional vapour channels. From measurement results the expected heat and mass transfer intensification, which would be enough for a thermally efficient heat pump, is observed. It is also concluded that an exact dimensioning and a proper preparation of the matrix are crucial for reaching the required cooling or heating performance.

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More than 70% of the SS removal from POME was achieved at the thawing rate less than 5 ml/min from 200 g of the frozen POME. However, the efficiency of the SS removal deteriorated at a higher thawing rate (7.1–13.6 ml/min). In addition to SS removal, concentration changes of thawed solution occurred at a lower thawing rate. At thawing rates from 1.7 ml/min to 4.2 ml/min, the melted solution was concentrated 1.2–1.3 times and 1.2–1.4 times respectively according to the COD soluble index and electrical conductivity index. Thus, the thawing rate played an important role in the freezing and thawing of POME for the purposes of SS removal and concentrating the effluent.

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Wood was treated in hot compressed water at 200–350°C without a catalyst to produce charcoal. The charcoal carbonized at various temperatures under hot compressed water was mainly analyzed by FT-IR in order to investigate the changes in the chemical structures during the carbonization process. The FT-IR spectra showed that the carbonization of wood was promoted by the increasing reaction temperature. The intensity of the peaks due to the -OH and -CH of wood became weak with the increasing reaction temperature. The dehydrogenation and deoxygenation in wood were observed during the treatment with the hot compressed water. The studies clarified that the carbonization of wood was promoted at low temperature using the hot compressed water.

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