Slug length estimation for gas-liquid slug flow in T-shaped microdevices with liquid film

13th IFAC Symposium on Dynamics and Control of Process Systems, including Biosystems DYCOPS 2022, Busan, Republic of Korea, 14–17 June 2022To realize stable long-term operation of microdevices with gas-liquid slug flow, the slug lengths have to be monitored and controlled, because they influence mass transfer performance. In this study, an experimental investigation was carried out to analyze the gas-liquid slug flow in a T-shaped microdevice with a liquid film. The experimental result showed that the pressures in gas and liquid feeding tubes oscillate periodically along the formation of a pair of gas and liquid slugs. Then, the correlation equation between the liquid film thickness and the number of capillaries was identified on the basis of the experimental data. Based on these results, a method for estimating slug lengths and liquid film thickness from measurements of feed pressure and feed flowrate was developed. The developed method is non-invasive and does not affect slug formation or the manner of gas-liquid slug flow. Its effectiveness was assessed through an experimental case study, and the relative root mean square errors of estimated slug lengths were within 8.5%. The result show that the developed method can be applied to the monitoring of slug lengths

CFD-based Design of Multi-tube Heat Exchange Type Compact Reactor

The production capacity of compact reactors with micrometer or millimeter-scale channels or tubes is increased by numbering-up. In previous studies, a multi-channel plate type reactor and a multi-tube type reactor (MTR) were developed and applied to extraction and reaction operations. Fluid distribution has often been evaluated to design these reactors, but temperature control, which is critical to the reaction, has not been fully considered. It is important to solve this problem and establish a design method. In this study, computational fluid dynamics (CFD)-based design was performed so as to achieve the uniform flow and temperature distributions among the reaction tubes in the MTR, where an exothermic reaction proceeds in each tube with an immobilized catalyst and the reaction temperature is controlled by a coolant flowing outside the tubes. Effects of multi-tube arrangement of lattice, concentric circles and single circle, shell cross-sectional shape of circle, rectangle and ring, and reaction tubes with or without catalyst-free inert sections on the reactor performance were investigated by CFD. The usefulness of a two-step approach of designing the MTR after designing the double-tubular reactor was confirmed through a case study on parallel reactions

シリカ デ ヒフク サレタ タンソ タンジ Pt ショクバイ ノ チョウセイ ト ユウキ ハイドライド ダツスイソ ショクバイ エノ オウヨウ

Carbon-supported Pt metal nanoparticles covered with silica layer including phenyl or methyl groups were prepared using successive hydrolysis of 3-aminopropyl-triethoxysilane (APTES) and phenyltriethoxysilane (PhTES) or methyltriethoxysilane (MTES). The Pt catalyst covered with silica layers containing functional groups showed higher activity in the cyclohexane dehydrogenation, compared with Pt catalysts covered with a silica layer containing no functional groups, because the microporous structure of silica layers which wrapped Pt metal particles increased the diffusion capability of cyclohexane. The Pt/CB nanoparticles covered with microporous silica layers showed the high sintering resistance of Pt metal particles to thermal treatment at 973 K in a H2 atmosphere as compared with Pt/CB. As a result, this catalyst showed higher catalytic activity for cyclohexane dehydrogenation than Pt/CB after thermal treatment

Preparation of Rice Bran Protein Solutions Using a Water-Based Extraction Process

Rice bran (RB), which is a waste product of the rice industry, has great potential for use as a source of new protein supplements. In this study, the extraction of soluble proteins from rice bran was conducted using a water-based extraction method with the aid of sonication extraction and a hybrid sonication/thermal treatment approach, known as the soni-auto hybrid method. Both extraction methods were explored and compared to determine the most efficient extraction process using the one-factor-at-one-time (OFAT) method. The parameters studied and their experimental ranges for both extraction methods were as follows: sonication time = 5-45 min, sonication temperature = 30-80 °C, and feed-to-solvent ratio = 1:5-1:80 (g:mL). The most efficient extraction method was then used for optimization by means of response surface methodology (RSM) based on the central composite design (CCD) model. It was found that the soni-auto hybrid method exhibited a superior extraction performance compared with sonication alone, wherein the protein concentration was increased by up to 18% while maintaining a comparable quality. The use of this hybrid treatment approach also reduced the sonication time from 35 to 30 min and the sonication temperature from 50 to 45 °C. The optimal soni-auto hybrid conditions were determined by RSM to be a temperature of 50 °C, a feed-to-solvent ratio of 1:20, and an extraction time of 30 min; these conditions produced a protein concentration of 17.174 mg/mL. Finally, evaluation of the surface morphology and functional groups on the protein confirmed that the hybrid soni-auto approach provided a higher protein concentration without significantly affecting the protein structure or quality

Application of a Microreactor in the Oxidative Dehydrogenation of Propane to Propylene on Calcium Hydroxyapatite and Magnesium ortho-Vanadate Doped and Undoped with Palladium

A microreactor was employed for the oxidative dehydrogenation of propane to propylene in order to suppress a deep oxidation of the resultant propylene to CO and CO2. Magnesium ortho-vanadate, doped and undoped with palladium, and calcium hydroxyapatite, were used as catalysts while the reaction temperature was controlled by steady- and unsteady-state conditions. The enhancement of the selectivity to propylene was the most advantageous effect from using the microreactor, and it occurred when calcium hydroxyapatite was used under an unsteady-state. For example, the selectivity to propylene was 0 and 73.0% using a fixed-bed continuous-flow reactor and the microreactor, respectively, under almost identical propane conversion of 3.1 and 3.2%, respectively. The advantageous effect was also achieved, although to a lesser degree, when magnesium ortho-vanadate was used undoped with palladium under both steady- and unsteady-state conditions. However these advantageous effects of the microreactor were not observed with magnesium ortho-vanadate doped with palladium. With regard to the selectivity to propylene, the redox nature of the catalysts seemed to influence the performance of the microreactor

Scanning curves of water adsorption on graphitized thermal carbon black and ordered mesoporous carbon

Adsorption isotherms of water on porous carbons generally show large hysteresis loops whose origin is believed to be different from simple gases adsorption in mesoporous solids. In this paper, we discussed in details the behavior of water adsorption isotherms and their descending scanning curves for two carbons of different topologies, a highly graphitized thermal carbon black, Carbopack F, and a highly ordered mesoporous carbon, Hex. For both solids, very large hysteresis loops are observed, but their behaviors are different. For Carbopack F, the loop extends over a very wide range of pressure and the loop is larger when the descending is started from a higher loading; while for Hex, the hysteresis loop shows distinct steps, the number of which depends on the loading where the descending starts. By carefully analyzing the scanning curves from different loadings, we established the mechanism of water adsorption in Hex as a sequence of three steps: (1) water molecules adsorb on functional groups located at the junctions between adjacent basal planes of graphene layers, (2) growth of water clusters around the functional groups, and (3) bridging of adjacent clusters to form larger clusters, followed by a complete filling of mesopores

シリカ ヒフク Pd ショクバイ ノ カイハツ ニ カンスル コクサイ キョウドウ ケンキュウ : カイブンシキ シクロヘキサン ダッスイソ ハンノウ ニオケル シンタリング タイセイ ト ショクバイ カッセイ

Here we developed silica-coated Pd catalysts and applied to liquid phase catalytic reaction such as dehydrogenation of cyclohexane. Carbon black (CB)-supported Pd catalysts (Pd/CB) were covered with organosilica layers via the hydrolysis of phenyltriethoxysilane (PhTES). Coverage of Pd nanoparticles with organosilica layers suppressed particle sintering of Pd, as compared to the case of uncovered Pd/CB. The organosilica layers had hydrophobic properties because of the presence of phenyl groups. As a result, the organosilica-coated Pd catalysts prepared using PhTES showed superior catalytic performance for cyclohexane dehydrogenation, even after reduction at 623K under H2 atmosphere

Application of Heavy-Metal-Free Pd/C Catalyst for the Oxidative Dehydrogenation of Sodium Lactate to Pyruvate in an Aqueous Phase under Pressurized Oxygen

According to previous reports, the oxidative dehydrogenation of lactic acid to pyruvic acid in an aqueous phase does not proceed with Pd/C, while Pd/C doped with Te or Pb has catalytic activity at atmospheric pressure and 363 K in an aqueous NaOH solution at a pH of 8. Since use of heavy metals, such as Te or Pb, is inconsistent with green chemistry, a heavy-metal-free Pd/C catalyst is employed in the present study. The oxidative dehydrogenation of sodium lactate to sodium pyruvate in an aqueous phase at 358 K under pressurized oxygen at 1 MPa proceeded favorably using Pd/C with no adjustment of solution pH. Under pressurized oxygen, the catalytic activity of Pd/C was similar to that of Pd/C doped with either Te or Pb. This result suggests that a heavy-metal-free Pd/C catalytst might also be applied to other catalytic reactions. As an alternative to doping Pd/C with Te or Pb, the dissolution of gaseous oxygen into the reaction solution significantly enhanced the catalytic activity of Pd/C. To show the contribution of the dissolution of gaseous oxygen, the effects of the volume of oxygen in the reactor (stainless autoclave) on the reaction rate and the activity were examined. The activation parameters thus obtained reveal that the volume of oxygen in the reactor is a more important determinant of catalytic activity than the activation of the reaction itself