A new device, known as a double-pass counterflow mass exchanger, is a circular tube divided by inserting a permeable barrier in parallel into two subchannels with sinusoidal wall fluxes, resulting in considerable improvement of the device performance in mass transfer compared with that in an open conduit. An analytical method is proposed to predict the concentration distribution and mass-transfer efficiency enhancement by setting a general solution form for the laminar double-pass counterflow concentric-tube mass exchangers with sinusoidal wall fluxes. Theoretical results show that a suitable adjustment of the permeable-barrier position can effectively enhance the mass transfer rate, leading to an improved device performance. The effects of the permeable-barrier location on the mass-transfer efficiency improvement and power consumption increment, as indicated from theoretical predictions, have also been delineated. One may follow the procedure described in the present paper and determine the economical feasibility for each particular application in operating double-pass devices.

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The most important parameters in adsorption column design are pressure drop, adsorbent capacity, reaction kinetics and adsorbent regeneration. However for those applications where flow losses have to be minimized, the pressure drop is the most important parameter. The Ergun equation is used for pressure drop calculations. For atmospheric operations, it does have good results, but it is inconsequential for sub atmospheric conditions and should be revised. The empirical data deviation from Ergun equation results for sodium fluoride adsorbents and medium vacuum conditions is studied in this paper. It shows that, the deviation risies up with vacuum increasing. As a result, using the Ergun equation in sub atmospheric conditions has too much error and causes useless adsorption column design.

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The purification of BSA from yeast/BSA binary suspension using batchwise centrifugal filtration under various conditions is studied. Effects of suspension pH and rotational speed on the cake properties, filtration rate and protein recovery are discussed. The experimental results indicate that the filtration rate is significantly affected by the cake growth at the initial periods of filtration, and no evident rate difference can be found among different suspension pH values under a low rotational speed. However, the effect of cake compression becomes more dominant as rotational speed increases. The compression of yeast cake is irreversible and strongly affected by the suspension pH especially under a high rotational speed. The cakes formed at pH 3.0 possess the highest compressibility due to the yeast coagulation, while the average specific resistance of cake is the lowest at pH 7.0 because of the high zeta potential of yeast cells. In addition, the recovery of BSA can be as high as 95–98% under the operating conditions of this study. Since the BSA concentration in the filtrate keeps constant during the filtration under various rotational speeds, the recovery of BSA is dependent solely on the filtration rate in spite of the little adsorbed amount on the yeast cells. To operate under higher rotational speed and pH 7.0 is optimal from the viewpoint of economic operation time and protein recovery.

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In this study, a single droplet experiment and a spray combustion experiment for an emulsified fuel were carried out. The purpose of the single droplet experiment was to investigate the characteristics of the secondary atomization and the dominant factor in determining micro-explosion or puffing. In the spray combustion experiment, the spray combustion characteristics of the emulsified fuel used in the single droplet experiment were investigated. In the single droplet experiment, individual emulsified fuel droplets suspended from a thermocouple were set into an electric furnace. As a result, many forms of secondary atomization were observed. While the superheat temperature ranged between 50 and 80 K at the occurrence of micro-explosion, it ranged between 20 and 50 K when puffing occurred. It was found that the probability of the micro-explosion increased with an increase in the superheat temperature. The emulsified fuel had a drastic effect on the spray combustion characteristics. When the emulsified fuel was used, the gas temperature was reduced in the upstream region. However, the gas temperature increased rapidly and there was no peak of the gas temperature in the axial direction, unlike kerosene. Moreover, the radial distribution of the gas temperature of the emulsified fuel became uniform, also unlike kerosene, as a result of the improvement of the evaporation and the mixing caused by the secondary atomization as shown in the single droplet experiment.

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This work presents a dynamic simulation and a design control system for the thermal decomposition of nitrogen trichloride during electrolytic chlorine production. Nitrogen trichloride is an extremely unstable and explosive compound and the decomposition process has two main problems: variability of the reactor temperature and loss of solvent. The process was simulated using the AspenTech^® simulator and the simulations were validated with industrial plant data. The dynamic analysis showed that the process presents integrating behavior and that the loss of the solvent is strongly affected by the dynamics. The implementation of the results of this work at the industrial plant resulted in a significant decrease in the variability of the reactor temperature as well as reducing solvent loss.

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In microdermabrasion (MD), the stratum corneum (SC), which controls percutaneous absorption of drug molecules, is abraded and partly or completely removed by fine corundum powder under reduced pressure. The objective of this study is to evaluate the effect of MD on SC barrier capacity. Hairless mouse skin was treated by SkinCrystal, a MD system, with various operating vacuum powers (V) and treating duration (L). A matrix-type membrane device fabricated by ethylene vinyl-acetate (EVA) copolymer with drug was placed on the skin. The SC barrier capacity was examined by skin penetration experiment in vitro. The skin penetration flux increased with increasing V and L. The fraction of SC removed was defined by the following equation F = (flux_{MD treated skin} – flux_{intact skin})/(flux_{stripped skin} – flux_{intact skin}), where F takes values within the range of 0 (intact skin) to 1 (stripped skin). For SkinCrystal, F is a function of V² and L (F = 0.44V²L, r² = 0.83). The SC barrier capacity is controlled with the parameters of the MD system, V and L.

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Optical properties of semiconductor nanocrystals vary with temperature; e.g., luminescence efficiency/PL intensity decreases with increasing temperature. It is then possible to utilize these nanocrystals as a temperature sensor for non-intrusive scanning/construction of 3-D temperature distribution in a microchannel. In this work, we evaluated the applicability of CdSe/ZnSe/ZnS core/shell nanocrystals as a 3D temperature sensor. Using this temperature-sensing material synthesized and dispersed in a solution flowing through a locally heated microchannel, we measured the liquid temperature distribution and compared the measurement results with the corresponding numerical simulation.

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The catalytic effect of three kinds of potassium salts on cellulose pyrolysis kinetics and products was studied on a thermogravimetric analyzer coupled with a Fourier transform infrared spectroscopy. Experimental results showed that potassium salts catalyzed the dehydration and depolymerization reactions in the initial pyrolysis stage, enhanced the release of oxygenated gases, intensively catalyzed the formation of char, and restrained the production of volatiles. Kinetic modeling showed that the presence of potassium ions provided a mechanistic route with lower activation energy, and accelerated the pyrolysis rate. Both KCl and K₂CO₃ restrained the release of levoglucosan, glycoaldehyde and C=O containing compounds, while K₂SO₄ largely promoted the formation of levoglucosan. The presence of KCl and K₂CO₃ might have retarded the unzipping reaction at the terminal units of the cellulose chain, and thus restrained the formation of levoglucosan. K₂SO₄ exhibited different catalytic mechanisms, which uniquely catalyzed the formation of levoglucosan.

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The presence of tars during biomass gasification is a major problem in the gas-processing systems and internal combustion engines. In order to develop a technology for the reduction of tars at low temperatures, the reactivity of active oxygen species O^– in the oxidative decomposition of biomass tars using a 12CaO·7Al₂O₃ (C12A7) crystal was investigated experimentally. The C12A7 was used as a less expensive carrier of O^– radicals. Tars were produced from pyrolyzed wood chips at 1273 K and decomposed in the presence of C12A7/O^– in a stream of pure nitrogen gas at 623–673 K. The results showed that the tars could be oxidized in the presence of C12A7/O^– at a temperature of 623 K or above, which may not be achievable by other methods.

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The main aim of this paper is to improve the current sawmilling process by utilization of the products from thermal treatment of wood residues. Firstly, batch thermal treatments of rubberwood sawdust were conducted under various conditions to study the effects of the conditions on the yields and the characteristics of the products, pyroligneous acid and activated carbons. Sufficient amounts of crude pyroligneous acid and activated carbon were obtained. In all conditions, the produced pyroligneous acid contained the same amount of components which are essential as preservative, e.g., phenolic compounds. The activated carbon especially that produced under steam atmosphere exhibited a relatively high surface area that is suitable as an adsorbent. Secondly, the model aqueous solution of a single harmful phenolic compound contained in the pyroligneous acid was subjected to batch equilibrium adsorptions with the activated carbon prepared by the above treatment. The activated carbon effectively adsorbed the phenolic compounds in the pyroligneous acid. The overall capacity of the rubberwood activated carbon to fully adsorb any component in pyroligneous acid was considerably higher than the amount of the component produced from the same rubberwood sawdust, showing the feasibility of treating the wastewater containing pyroligneous acid with the activated carbon. Finally, based on these experimental results, we synthesized the outline of an improved sawmilling process: the wood residues are thermally treated to obtain pyroligneous acid, activated carbon, and off-gas; the pyroligneous acid is used as wood preservative instead of the conventional toxic one, the wastewater containing the pyroligneous acid is treated by the activated carbon, and the off-gas with addition of residues is used as a heat and energy source for these additional operations. The proposed method is promising and reliable to give the desired performance to improve the manufacturing process and overcome environmental problems.

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In order to lower the price of polylactic acid, it is necessary to reduce the energy required to produce energy lactic acid, which is its main material. In this work, we focused on a lactic acid recovery system after lactic acid fermentation, and proposed a new recovery process which combines the reverse osmosis (RO) method with ammonia removal method. Results shows that more than 90% of the glucose and ammonia were removed.

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