Propionic acid is one of the materials that are used for making cellulosic solvent in pharmaceutical industries. Little information of equilibrium data for this material is available in the literature. In this research the liquid–liquid equilibrium data for the ternary system of (water + propionic acid + diethyl ketone) was measured at 25, 35, 45°C. Complete phase diagrams were obtained by determining solubility and tie-line data. The reliability of the tie-line data was ascertained by using the Othmer and Tobias correlation. Distribution coefficients and separation factors were evaluated for an immiscibility region. The experimental tie-line data were also correlated with NRTL and UNIQUAC models and binary interaction parameters of these models have been reported. Both models satisfactorily fit obtained experimental data.
This study presents a new ebulliometer which is able to compensate for the vapor hold-up problem commonly experienced when measuring vapor–liquid equilibria. Firstly, the influence of the vapor hold-up was examined by measuring the boiling points for the ethanol + toluene system at 53.33 kPa, and it was confirmed that the vaporization coefficient of the newly-developed ebulliometer was 2.2%. Secondly, the boiling points of three binary systems of ethanol + toluene, ethanol + cyclohexane, and benzene + cyclohexane, were determined in the range of 53.33 to 98.66 kPa. In addition, the experimental boiling point data were satisfactorily correlated using the NRTL equation. Finally, the determined NRTL parameters were evaluated by calculating the vapor–liquid equilibria under the same conditions as the thermodynamically reliable values in the literature.
A quadratic Padé-type extension of the Wilson equation is proposed as a general mixture model for highly nonlinear response behavior. The model includes the well-known Wilson, T–K Wilson, the quadratic Scheffé polynomials and their Padé extensions. It features excellent data correlating capabilities for binary and multicomponent heats of mixing data.
In the present work, the flow pattern in pipe flows has been simulated for drag reducing fluids using a low Reynolds number k–ε model. The model uses a non-linear molecular viscosity and damping function to account for near wall effects. The comparison between the predictions and the experimental profiles of axial velocity and kinetic energy are in good agreement. A systematic study has been undertaken to investigate the effect of rheological parameters and to consider the modification to the flow that arises in the presence of a fluid yield stress.
For understanding of gas–liquid mixing characteristics in an aerated agitated vessel, knowledge of bubble size distribution is very important. In this work, bubble size distribution and interfacial area were investigated for making a comparison of a pitched blade paddle creating upward flow with the Rushton disc turbine and Scaba SRGT impeller, which are commonly recommended for gas–liquid mixing. The results indicated that the size of the bubble created by the up-pumping of the pitched blade paddle could be kept small and the enhanced interfacial area could be maintained constant until 22.2 vvm, while large bubbles increased and the interfacial area decreased with an increasing gas flow rate, 4.8–15.8 vvm, for DT and SRGT. The correlation of the Sauter mean diameter with the gas flow rate Qg was derived at large gas flow rates for three impellers.
A compact plate methane steam reformer consisting of closely spaced plates of electrically heated alumite catalysts (EHAC), in which endothermic and exothermic reactions take place in the alternate channels, has been numerically studied. One reforming channel was integrated with two combustion channels to constitute a single reformer unit, which was easily placed and scaled up. Furthermore, the novel catalyst, i.e., EHAC, made by an anodization technology, has the characteristic of being electrified through itself, which was applied in the start-up acceleration strategy. To investigate the performance of the reformer in different operation situations, 2-D steady-state and dynamic multiphase models for heat and mass transfer coupling with velocity distribution were carried out in this work. The results from the steady-state simulation suggested that the inlet temperature and gas flow directions played important roles in the performance of methane steam reforming reactions. Dynamic simulation results show that the start-up process took 45 min without any acceleration strategies, while it took no more than 10 min in the case of with electrically heating at the beginning of the process.
The calcination of [tetra (2,4,6-trimethylphenylthio)] tin under an argon atmosphere gave a nano-sized SnS/carbon cluster composite material. ESR spectral examinations showed the possibility of a photoresponsive electron transfer from the carbon clusters to the SnS particles.
In this paper, an intelligent control scheme using a fuzzy single neuron controller (FSNC) is proposed for nonlinear process control. Different from the conventional three-parameter single neuron controller (SNC), the FSNC uses the fuzzy logic concept to build its nonlinearity rather than just mapping through a nonlinear saturation function. This effort, though it introduces additional tuning parameters, can greatly enhance the nonlinear capability for process control. A simple yet efficient parameter tuning algorithm has been developed, which enables the FSNC to learn to control the nonlinear process adaptively with merely observing the process output errors. Both the convergence of the proposed parameter tuning algorithm and the stability of the presented FSNC-based control system are guaranteed by utilizing the Lyapunov stability theorem. To demonstrate the applicability and effectiveness of the proposed intelligent control scheme, we apply it to the direct adaptive control of an unstable nonlinear CSTR. Comparisons with an adaptive SNC and PID controllers were performed. Extensive simulation results reveal that the proposed FSNC is promising and is well suited to the direct adaptive control of processes having severe nonlinearity.
A thin film of silica nanoparticles with highly ordered hemispherical macropores and an ordering factor, ØVP6, of 98% was proved to be obtained by the Voronoi polygon analysis. Firstly, a monolayer of submicron polystyrene latex particles (PSL) with silica nanoparticles is obtained by coating a binary suspension of PSL particles and silica nanoparticles on a glass substrate using a spin coater. Secondly, the PSL particles are completely decomposed by calcining the coated films at 400°C for 10 min, affording a thin film of silica nanoparticles with hemispherical macropores. The size of the hemispherical macropores can be controlled from 136 to 506 nm by choosing PSL particles as a template. Although the monolayer of PSL particles without silica nanoparticles has several point and line defects, the PSL particle monolayer with silica nanoparticles has few defects. The small size of the silica nanoparticles is preferable for highly ordered hemispherical macropores. We propose a model that explains the ordering mechanism of particles during drying. The thin film of highly ordered hemispherical macropores can be used as a template for microcontact printing due to its hemispherical shape, or as an anti-reflective film due to its optical properties.
Simultaneous measurement of methanol crossover (MCO) at the anode and CO2 crossover (CCO) at the cathode is carried out for the proper evaluation of a membrane-electrode assembly (MEA) in operation of a direct methanol fuel cell (DMFC). The effects of temperature (293–363 K), concentration of methanol in aqueous solution (1–3 mol/dm3), current density (0–0.4 A/cm2) and gas/liquid flow rate and relative humidity of gas at the cathode on MCO and CCO fluxes are investigated. With an increase in the current density, the MCO flux linearly decreases, while the CCO flux increases to a certain value, and reaches 15% of MCO flux at high current density (0.4 A/cm2). The MCO flux is strongly affected by the methanol concentration, temperature and current density, and slightly affected by the gas/liquid flow rate. An empirical equation is proposed for the MCO flux through an MEA in operation of a DMFC under ambient pressure, where liquid methanol and dry oxygen are fed to the anode and cathode, respectively.
We studied the hydrogen production from four kinds of wet food wastes using high pressure superheated steam, which is reactive water above the critical temperature and below the critical pressure of water. 1.8–2.0 mmoles of hydrogen gas were produced from 1 mmole of organic carbon in the wastes at 700°C, 10 MPa, 30 min, 20 of the molar ratio of water to organic carbon and 20 wt% of the potassium hydroxide to the organic content in the waste. The production of hydrogen gas was accelerated by increasing the temperature and molar ratio of water to organic carbon in the waste, but suppressed by increasing the pressure. On the other hand, the production of ammonia, which is a typical by-product of gasification of food wastes, reduced by increasing the temperature and decreasing the pressure. Judging from the experimental results, high pressure superheated steam with low pressure was more effective than supercritical water with high pressure. The calculated equilibrium mole fractions of hydrogen gas based on the ideal gas assumption agreed with the experimental data in wide temperature and pressure regions, but those of methane and carbon dioxide deviated from the data above 600°C.
A kinetic-measure was developed to explain time-resolved observations during the overall decolorization of organic dyes. Critical photonic times (CPTs) were calculated for the photocatalytic degradation of four organic textile dyes. Three different frequencies of UV were applied to the dyes. Use of CPT principles improved decolorization by 100%. Moreover, CPT calculations predicted dye resistivity and allowed the assessment of photon efficiencies and deficiencies in dyes and UV lamps combination. The derivatization and evaluation of CPTs from the slopes of the linear plots are presented.
The production of clean oil by thermal degradation of municipal waste plastics pretreated with supercritical alkaline alcohols has been investigated. When the municipal waste plastics was treated with the alcoholic solutions of NaOH at 300°C, the chlorine and nitrogen atoms present in the waste plastics eluted in the order of methanol > ethanol > 2-propanol > tertiary butanol. In the pretreatment with a methanolic solution of NaOH at 250–300°C for 30 min, these heteroatoms eluted in almost the same yields, 91.4–94.4 and 76.0–76.8%, respectively. However, the yields of these heteroatoms eluted decreased to 59.7 and 71.7%, respectively, in the pretreatment at the subcritical temperature of 225°C. In the pretreatments at 250–300°C for 30 min, the total chlorine content in the resultant oils was 16 ppm and it increased markedly to 85 ppm in the pretreatment at 225°C. The total nitrogen content in the oil increased gradually from 34 to 64 ppm upon temperature decrease from 300 to 225°C at the pretreatment step. An oil, whose total chlorine and nitrogen contents were 16 and 47 ppm, respectively, was thus produced at the yield of 62 wt% via the pretreatment with methanolic solution of NaOH at 250°C. The boiling point distribution, type of hydrocarbons, and physical and physicochemical properties of the oil such as kinematic viscosity and pour point were determined and compared with those of the oils produced in the commercial plants in Japan.
The degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was conducted by ozonation, TiO2/UV treatment only, and two-stage treatment of ozonation followed by TiO2/UV treatment. In the case of ozonation, 2,4-D could be degraded and vanished within about 10 min at pH 9 and 20°C, but the TOC value was reduced by only about 40% by 30 min ozonation. In the case of TiO2/UV treatment, about 5 d was needed for complete disappearance of 2,4-D at pH 5 and 20°C. On the other hand, when the two-stage treatment of ozonation plus TiO2/UV treatment was applied, 90% decline of TOC was achieved within about 20 h, i.e., 30 min ozonation and 20 h TiO2/UV treatment thereafter. Furthermore, 90% of chloride ions in 2,4-D were liberated by the two-stage treatment. From a bioassay test of the two-stage treated water by the use of an osteoclasts of goldfish scales or Daphnia magna, it was found that 2,4-D was degraded into harmless substances with little estrogen activity and toxicity.