The three-dimensional simulation of vortex on the bottom of a particle in gas-liquid two- phase flow

The sophisticated industrial applications demand deep knowledge of local flow hydrodynamics on a particle surface in fixed bed reactors in order to improve process efficiency, particularly micro- (or particle-) scale of gas-liquid two-phase flow, which the study of vortex on the bottom of a particle is much more meaningful. The three-dimensional numerical simulations of gas-liquid two phase flow passing a spherical particle were investigated using Computational Fluid Dynamics (CFD) methodology with the volume of fluid (VOF) method. The effects of gas velocity, liquid velocity, liquid-solid contact angle, surface tension coefficient, and liquid viscosity on the interface status of fluid flow were presented in this paper. The simulation conditions were particle diameters of 10mm, water and air as liquid and gas respectively, droplet size 4mm, and an atmospheric pressure. Results show that the droplet movement and gas streamlines are greatly dependent on the air flow conditions and the liquid physical conditions. To better observe the flow field around the liquid droplet, the 3D plot is drawn for the contact angle of 50° with the gas velocity of 1.0m/s at the time instant of 0.015s as shown in Figure 1. Vortices are produced on the bottom of a particle known as Von Kármán vortex street, which have the opposite direction of rotation and the double row arrangement vortex. In addition, vortices are found to be more obvious and farer from the particle at higher gas and/or liquid velocities, and the droplet moves faster with the increasing gas velocity (0.2m/s-2.0m/s) and liquid velocity (0.24m/s-0.465m/s). Moreover, the generated vortices can be clearly observed at downstream of particle, and the droplet shape varies with the flow time. Vortex radius changes from 0.5mm to 2.5mm with the time going at the gas velocity 0.5m/s and liquid velocity 0.24m/s. The liquid-solid contact angle between 40° and 80° mainly affects particle surface wettability, which results in the different droplet shape and flow gas streamlines. At the beginning, the shape of the droplet is spherical and thereafter it changes to appropriate shape according to the surface properties and the contact angle. When the liquid-solid contact angle is 50°, vortex is comparatively density which radius is only 0.5mm initially, and then changes to 3.5mm approximately with an increase of the flow time. Meanwhile, the surface tension can affect the contractile properties and the gas streamline Please click Additional Files below to see the full abstract

Effect of cultivar and fertilization on functional value of sweet potato (Ipomoea batatas L.)

Batat (Ipomoea batatas L.) je višegodišnja tropska vrsta iznimno velike nutritivne vrijednosti korijena i lista. Pripada u skupinu funkcionalne hrane zbog značajne količine specijaliziranih biljnih metabolita, antioksidativnih spojeva (vitamina, polifenola, karotenoida) i sadržaja esencijalnih minerala, dijetalnih vlakana, uz niski glikemijski indeks korijena. Sastav i koncentracija specijaliziranih biljnih metabolita su promjenjivi, zbog utjecaja genotipa, ekoloških uvjeta uzgoja i gnojidbe, što predstavlja problem u proizvodnji povrća kao funkcionalne hrane, od koje se očekuje ujednačena hranidbena i zdravstvena vrijednost. S obzirom na povećan interes za proizvodnjom batata stabilne antioksidacijske aktivnosti te malobrojne rezultate o toj problematici, uočena je potreba istraživanja utjecaja sorte i rastuće gnojidbe posebice kalijem na komponente prinosa, udio polifenola i antioksidacijsku aktivnost korijena i lista batata, u cilju dobivanja smjernica tehnologije uzgoja batata povećanih nutritivnih vrijednosti i ujednačene kvalitete. S tim ciljem je u SZ Hrvatskoj na Pokusno-pokaznom polju u Varaždinu, provedeno dvogodišnje istraživanje, radi utvrđivanja smjernica tehnologije uzgoja batata veće funkcionalne vrijednosti. Tijekom 2008. i 2009. godine postavljeni su istovjetni dvofaktorijalni poljski pokusi po metodi slučajnog bloknog rasporeda u četiri ponavljanja. Prvi faktor je sorta u dvije razine (ʹBatʹ i ʹBoniatoʹ), i drugi gnojidba dušikom i kalijem u tri razine (kontrolna gnojidba odnos N i K 1:1, druga razina odnos N i K 1:2,5 i treća odnos N i K 1:5). Tijekom istraživanja s obzirom na sortu i rastuću gnojidbu dušikom i kalijem ostvareni su u obje godine veći prinosi korijena m-2 (ʹBatʹ 2,78 do 4,67 kg i ʹBoniatoʹ 2,70 do 4,92 kg) i lista (ʹBatʹ 1,82 do 3,73 kg i ʹBoniatoʹ 3,68 do 5,33 kg) veći postotak K u korijenu (ʹBatʹ 1,49 do 2,34 % i ʹBoniatoʹ 1,20 do 1,81%) i listu (ʹBatʹ 2,22 do 3,20 % i ʹBoniatoʹ 2,72 do 3,68 %), veći postotak N u korijenu (ʹBatʹ 1,49 do 1,80 % i ʹBoniatoʹ 1,55 do 1,83 %) i listu (ʹBatʹ 3,16 do 3,73 % i ʹBoniatoʹ 3,04 do 3,38 %),veći udio krupnije frakcije korijena (ʹBatʹ 17,29 do 19,86% i ʹBoniatoʹ 9,61 do 17,79 %), veći udio ukupnih polifenola korijena sorte ʹBatʹ (3,75 do 16,08 mg GAE g-1 st) i ORAC vrijednosti korijena (ʹBatʹ 15,10 do 73,03 µmol TE g-1 st) i veći udio flavonoida u listu (ʹBatʹ 8,27 do 11,58 mg g-1 ST i ʹBoniatoʹ 9,59 do 20,61 mg g-1 ST), dok je udio ukupnih polifenola u listu (ʹBatʹ 49,68 do 50,25 i ʹBoniatoʹ 51,77 do 53,31 mg g-1 ST) i ORAC vrijednosti (ʹBatʹ 402,50 do 422,17 µmol TE g-1 ST i ʹBoniatoʹ 439,90 do 474,96 µmol TE g-1 ST) bio veći u drugoj godini istraživanja. Obje sorte su uz veću razinu gnojidbe dale veće prinose korijena i lista, veći udio N, sirovih proteina, K, dok je udio ukupnih polifenola i antioksidacijska aktivnost bila značajno veća u listu u odnosu na korijen kod obje razine gnojidbe.Sweet potato (lat. Ipomoea batatas) is a vegetable species of extremely high nutritional value of roots and leaves. It belongs to a group of functional foods because of the significant amount of specialized herbal metabolites, antioxidants (vitamins, polyphenols, carotenoids) and the content of essential minerals, dietary fibres, with low glycaemic root index. Polyphenol compounds include a large group of specialized plant metabolites that contribute to better organoleptic and nutritional components of vegetables and fruits. Specialized secondary herbal metabolites are compounds synthesized in plants as secondary metabolic products in the interaction of plants with agro-environmental conditions. Specialized metabolites differ according to the chemical structure and their function in the organism. In food, specialized metabolites are most often defined as natural non-nutritional food ingredients, which have health-beneficial effects if consumed in adequate quantities. Moreover, antioxidants play an important role in human nutrition due to the strong function of protecting the body and boosting the immune system. By consuming foods rich in antioxidants, we help the body fight against various diseases caused by free radicals. The composition and concentration of specialized plant metabolites are variable due to the influence of genotypes, ecological conditions of cultivation and fertilization, which presents a problem in the production of vegetables as a functional food, which is expected to have a consistent nutritional and health value. The functional value of food is found in products that, besides basic nutritional value, have a positive effect on human health, preventing and reducing the risk of developing certain diseases. Due to the content of specialized metabolites, sweet potato is classified into functional foods because besides being a good source of minerals and vitamins, it supplies the body with important antioxidants. Antioxidants are produced in the cells or are introduced into our body through food intake, and function in several ways: they prevent the formation of new free radicals in the body, they destroy the radicals created in the body, or repair damage in the cells created by the action of free radicals. Oxidative stress implies a shift of balance in cellular oxidationreduction reactions in the direction of oxidation. Oxidative stress causes excessive formation of free radicals of oxygen, resulting in the loss of balance in creating free radicals and the inability of a cell to disintegrate them, and causing changes related to cell damage. The root and leaf consumption of sweet potatoes is associated with various positive physiological effects on health, such as antioxidant activity, ant mutagenicity, anti cancerogenicity, antimicrobial activity, and antidiabetic effect. Functional values of the sweet potato prompted producers to commercially breed sweet potato, as a new vegetable crop in Croatia. Due to the increased interest in the production of sweet potato with stable antioxidant activity and a small number of results on this problem, the need to investigate cultivar influence and growing fertilization, especially potassium on yield components, polyphenol concentrations and antioxidant activity of its root and leaf, has been recognized. With this aim, a two-year research was conducted in the Experimental-demonstration field in Varazdin to determine the guidelines for the breeding technology of equally balanced but nutritional and functional values of the sweet potato. During 2008 and 2009, identical twofactor polymorphisms were set up according to the method of randomized complete block design with four repetitions. The first factor is the variety in two steps, and the second fertilization with nitrogen and potassium in three steps. Two types of fertilization (ʹBatʹ and ʹBoniatoʹ) and two increased fertilization levels (500 and 1000 kg ha-1 NPK 7:14:21) were carried out with the addition of potassium salt K2SO4 to achieve a ratio of N:K 1:2.5 and 1: 5t. As a control variant, a lower fertilization level was used with the ratio N:K 1:1 with 250 kg ha-1 NPK 15:15:15. Transplant production with a lump of substrate in polystyrene containers was organized in the protected area of the Department of Vegetable Crops of the Faculty of Agriculture. Planting was carried out in mid-May, with 2 plants per m2 on raised bed covered with PE film, or 40 plants per basic parcel of 20 m2. Sweet potato transplants were planted manually on a 1.2 m spacing distance and a 0.4 m line spacing, enabling 2 plants per square meter. Fertilization was performed prior to machine shaping and setting of PE film. Temperatures and rainfall were monitored daily on CDA devices. Thirty-sixty days after planting, leaves and stems were counted on each plot, and the length of the stem and leaf area index was measured, while the total yield of leaf mass and root was weighed at the end of the vegetation. After the roots’ transport and storage, individual weighing of each root was performed, in order to calculate the share of individual root fractions and the influence of variety and fertilization on root size and marketable yield. The reference root and leaf sample were analyzed on the content of dry weigh, nitrogen, phosphorus and potassium at the Faculty of Agriculture, while total and individual polyphenols and antioxidant activity were analyzed at the Faculty of Food Technology at the Department of Biochemical Engineering. During the study, the validity of varieties was affirmed, along with fertilizers and their interaction on the amount of dry weigh in the leaf in both research years (ʹBatʹ 5.97 to 7.34 %, ʹBoniatoʹ 5.81 to 7.29 %), on raw protein in the leaf (ʹBatʹ 18.43 to 23.34 %, ʹBoniatoʹ 18.81 to 21.13 %), the total amount of N in the leaf (ʹBatʹ 2.95 to 3.74 %, ʹBoniatoʹ 3.04 to 3.38 %), (ʹBatʹ 0.22 to 0.33 %, ʹBoniatoʹ 0.21 to 0.34 %), quantity of K in the leaf (ʹBatʹ 2.22 to 3.20 %, ʹBoniatoʹ 2.23 to 3.68 %). The values of the antioxidant activity of the leaf and total polyphenols of the ʹBatʹ variety were growing (80.07 to 121.27 μmol Trolox g-1 DW, that is 14.38 to 23.17 mg GAE g-1 DW in 2008 and 396.87 to 422 , 2 μmol TE g-1 DW, or 48.52 to 50.25 mg GAE g-1 DW in 2009) and the ʹBoniatoʹ variety values were falling (in 2008, 126 to 104 μmol TE g-1 DW, ie 22,03 to 20,58 mg GAE g-1 DW and increased in 2009 to 396.38 to 474.96 μmol TE g-1 DW, that is 50.02 to 53.31 mg GAE g-1 DW). There were higher values of individual and total flavonoids in the leaf (ʹBatʹ 8.27 to 11.58 mg g-1 DW and ʹBoniatoʹ 9.56 to 20.61 mg g-1 DW). In the roots, bigger amounts of dry weigh were found in both research years (ʹBatʹ 14.50 to 25.28 %, ʹBoniatoʹ 16.15 to 23.64 %), as well as raw protein in the root (ʹBatʹ 9.18 to 11.25 %, ʹBoniatoʹ 8.56 to 11.44 %), the total amount of N in the root (ʹBatʹ 1.47 to 1.80 %, ʹBoniatoʹ 1.37 to 1.83 %), the amount of P in the root (ʹBatʹ 0.15 to 0.28 %, ʹBoniatoʹ 0.19 to 0.27 %), the amount of K in the root (ʹBatʹ 1.49 to 2.34 %, ʹBoniatoʹ 1.18 to 1.81 %). The values of the antioxidant activity of root and total polyphenols of the Bat variety were growing (9.26 to 17.40 μmol TE g-1 fw, that is 2.30 to 4.32 mg GAE g-1 fw in 2008 and 48.73 to 61,56 μmol TE g-1 fw, or 13.03 to 16.08 mg GAE g-1 fw in 2009). The values of the ʹBoniatoʹ variety were falling (30.69 to 20.34 μmol TE g-1 fw, or 7.62 to 5.05 mg GAE g-1 fw in 2008, and in 2009 51.00 to 48.08 μmol TE g-1 fw, while polyphenols were growing 11.88 to 13.02 mg GAE g-1 fw). During the study, varying impact of variety and fertilization and their interaction with morphological properties (length of stem, number of stems, leaf counts and leaf area index) was determined, with ʹBoniatoʹ variety having significantly higher values compared to the ʹBatʹ variety. The length of stem thirty days after planting (ʹBatʹ 27.68 to 29.90 cm, ʹBoniatoʹ 30.00 to 31.88 cm), number of stems (ʹBatʹ 1.57 to 1.80, ʹBoniatoʹ 1.63 to 1.80 ), number of leaves (ʹBatʹ 21.93 to 25.78, ʹBoniatoʹ 28.88 to 40.45), leaf area index (ʹBatʹ 200.40 to 235.63 cm2, ʹBoniato ʹ263.93 to 369.73 cm2). The length of stem sixty days after planting was (ʹBatʹ 50.93 to 61.45 cm, ʹBoniatoʹ 59.83 to 63.78 cm), number of stems (ʹBatʹ 12.80 to 15.38, ʹBoniatoʹ 15.40 to 18.28), number of leaves (ʹBatʹ 219.30 to 255.25, ʹBoniatoʹ 313.93 to 369.00), leaf area index (ʹBatʹ 2004.40 to 2330.70 cm2, ʹBoniatoʹ 2869.25 to 3305.95 cm2). In both years, variety and fertilization interactions provided higher root yields per m2 (ʹBatʹ 2,78 to 4,67 kg and ʹBoniatoʹ 2,70 to 4,92 kg) and leaves (ʹBatʹ 1,82 to 3,73 kg and ʹBoniatoʹ 3,68 to 5,33 kg), a higher share of a larger root fraction (ʹBatʹ 17.29 to 19.86 % and ʹBoniatoʹ 9.61 to 17.79 %) and a higher share of the total marketable root (ʹBatʹ 89.78 to 91,12 % and ʹBoniatoʹ 83.77 to 87.68 % in 2008 and in 2009 ʹBatʹ 78.1 to 86.57 % and ʹBoniatoʹ 87.80 to 90.95 %). Higher level of fertilization in both varieties gave higher roots and leaf yields, higher percentage of dry weigh and crude protein, higher amounts of N, P and K, and bigger quantities of larger roots fractions. Total and individual polyphenols and antioxidant activity were variable (higher in ʹBatʹ variety and slightly lower in ʹBoniatoʹ variety), but significantly higher in the leaf of both varieties compared to the root

The Reaction Mechanism of Acetaldehyde Ammoximation to Its Oxime in the TS-1/H2O2 System

A qualitative analysis for the ammoximation of acetaldehyde to its oxime in the TS-1(Titanium Silicalite-1)/H2O2 system was investigated using an in situ infrared spectrometer (ReactIR15). NH3 is first oxidized to NH2OH by TS-1/H2O2; then, CH3CH=NOH forms after NH2OH reacts with CH3CHO. That means the intermediate of this reaction is NH2OH instead of CH3CH=NH. Experiments have been conducted to verify the mechanism, and the results are in good agreement with the infrared findings

Effect of the Cr₂O₃ Promoter on Pt/WO₃-ZrO₂ Catalysts for n-Heptane Isomerization

Isomerate, the product of a light naphtha Isomerization unit, is a clean, high-octane gasoline blending component, which is free of sulfur content, aromatics, and olefins. However, the isomerization of the long-chain alkanes, such as n-heptane, is pretty difficult. As a result, this process has not been commercialized yet. In recent years, much attention has been paid to Pt/WO3/ZrO2 as an n-heptane isomerization catalyst due to its good thermal stability, strong acidity, simplicity of preparation, reusability and good isomerization activity. In this work, the Pt/WO3/ZrO2 catalyst was modified by various loading of metal Cr to improve the catalytic performance. The effects of WO3 content, Cr metal loading and calcination temperature on the catalyst characters and catalytic activity were studied. It is shown that Cr-Pt/WO3/ZrO2 with the loading of 18 wt% WO3 and 1.0⁻1.4 wt% Cr, prepared at the calcination temperature of 800 °C, has the highest activity. It was found that the octane number increases by 28 units through the isomerization of light naphtha feedstocks. In addition, the study on the stability of Cr-Pt/WO3/ZrO2 indicates that the catalyst is not deactivated after 500 h of the n-heptane isomerization reaction

An environmentally friendly acylation reaction of 2-methylnaphthalene in solvent-free condition in a micro-channel reactor

An efficient and solvent-free acylation of 2-methylnaphthalene (2-MN) is presented using acid chloride as both the acylating agent and solvent in a micro channel reactor. The effect of the catalyst, reactant ratio, mixing temperature, reaction temperature and reaction time on the product yield and selectivity was investigated. At room temperature with a reaction time of only 15 min, the target product, 2-methyl-6-propionylnaphthalene (2,6-MPN), was obtained in 72.3% yield with 73.8% selectivity, and 2-methyl-6-acetylnaphthalene (2,6-MAN) was obtained in 54.1% yield with 55.4% selectivity. The route of synthesis provides a more environmentally friendly and efficient method to prepare 2,6-MPN with no other toxic solvents and efficient mass transfer and heat transfer

Preparation, Characteristics, and Application of Bifunctional TiO2 Sheets

TiO2 is a high-reflectance material for preparing sheets during dry reagent chemical tests in detail. In this study, bifunctional TiO2 sheets with diffusive and reflective properties were prepared using TiO2 microspheres (particle size 2–3 µm) and cellulose acetate (CA). Factors such as the CA dosage, water content, mixing time, and the choice of surfactant were investigated. The structure and properties of the bifunctional TiO2 sheets were characterized by thermogravimetry and differential thermal analysis (TG-DAT), scanning electron microscopy (SEM), dynamic contact angle test and reflectance spectroscopy. By studying the above experimental results, it was concluded that the most optimal preparation conditions for preparing the bi-functional TiO2 sheets under natural drying conditions were as follows: the mass ratio of CA to TiO2 microspheres was 0.05:1; Triton-100 was used to improve the diffusion performance of the bifunctional sheets, after mixing for 5 h and coating. The light reflectivity of the bifunctional TiO2 sheets in the 420 to 800 nm range was higher than 90%. Serum diffused in the bifunctional TiO2 sheets reacted in the reagent sheets and formed uniform colorful spots. Considering the repeatability of spot proportion and light reflectivity, the sheet offered a uniform serum diffusion and good repeatability. So, the bifunctional TiO2 sheets are nominated as a promising material for dry chemical diagnostic reagents

Formation and Application of High Reflectivity Controllable Barium Sulfate Microspheres

This paper investigated the influence of reaction conditions on particle morphology. X-ray powder diffraction (XRD), particle size distribution (PSD), and scanning electron microscopy (SEM) were used to characterize the morphology of barium sulfate. The barium sulfate microspheres were synthesized with BaCl2, Na2SO4, and ethylenediaminetetraacetic acid disodium (EDTA·2Na). The reflectivity of the synthesized barium sulfate microspheres was greater than 99% in the range of 400–700 nm, which was characterized by a reflectance spectrometer. The morphology of the barium sulfate particles and their cross-section were observed by SEM. The prepared microspheres were applied to high-density lipoprotein dry tablets due to their high reflectivity, and the results showed that the prepared tablets had high sensitivity and good repeatability

Effect of Liquid Properties on Frictional Pressure Drop in a Gas-Liquid Two-Phase Microchannel

The flow characteristics in a ring-shaped microchannel with an inner diameter of 1 mm were studied in two-phase flow systems with air-water, air-glycerol aqueous solution and air-ethanol aqueous solution using the differential pressure method. The effects of liquid properties (surface tension and viscosity) and gas/liquid superficial velocity on frictional pressure drop were discussed. The experimental results show that the frictional pressure gradient increases with the increase of superficial gas velocity, superficial liquid velocity and liquid viscosity, and increases with the decrease of liquid surface tension, which has a good agreement with the literature values. The friction pressure drop data are compared with the classical models and correlations in literature, and a reliable correlation is proposed for prediction of two-phase friction coefficient in microchannels