Cereal brans are by‐products of the milling of cereal grains, which are mainly used as low value ingredients in animal feed. Wheat and oat bran is a rich source of bioactives and phytochemicals, ...especially phenolic compounds. Within this study, the application of ultrasound (US) technology to assist the extraction of phenolics from oat and wheat bran was investigated (20–45 kHz). Peleg’s mathematical model was used to study the kinetics of ultrasound-assisted extraction (UAE) and subsequent stirring of total phenolic compounds (TPC). The surface morphology of cereal brans after extraction was studied using SEM analysis. The excellent agreement was determined between the values of TPC calculated from Peleg’s mathematical model and actual experimental results. The constant that represents a time required for the initial phenolic concentration to be extracted to one-half of its initial value has been introduced (K1/2). It was shown that the TPC extraction kinetics was dependent only on K1/2 enabling fast kinetics fitting and comparison between extraction rates. Moreover, different values of K1/2 constant could indicate the differences in brans composition and consequently different influence of US pretreatment on these samples.
Vegetable oils were investigated as plasticizers to improve the sustainability of rubber compounding. The potential use of different vegetable oils as an alternative to petroleum‐based rubber process ...oils was reviewed. This article presents a literature review on the current understanding of the influence of vegetable oil properties on natural rubber (NR) compounding. Hansen solubility parameters of the vegetable oils were determined to assist with the selection of vegetable oil for NR. We believe that the use of Hansen parameters could make the use of vegetable oils in rubber more convenient and cost‐effective.
The potential use of different vegetable oils as an alternative to petroleum‐based rubber process oils was reviewed. This article presents a literature review on the current understanding of the influence of vegetable oil properties on natural rubber compounding.
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•SVR models show remarkably good predictability over the wide range of data.•Prediction of the SVR model for εG, Wld and kLa in the ELAR reported first time in literature.•SVR model ...was developed in the MATLAB and the LibSVM.•SVR model is scalable and extendable to other multiphase reactor systems.
For modeling, design and scale-up of the airlift reactors, it is crucial to estimate hydrodynamic parameters and volumetric gas–liquid mass transfer coefficient for different flow regimes. Prediction of these variables had begun by applying empirical power low correlations and later evolved in use of the artificial neural networks (ANN) as the best option available in the literature. The objective of this study was to present the support vector regression (SVR) model that predicts the gas holdup, downcomer liquid velocity and volumetric gas–liquid mass transfer coefficient values in the external-loop airlift reactor better than ANN. Furthermore, to demonstrate the applicability of the SVR model, it was used on the different literature data sets with wide-ranging databanks. The statistical error analysis revealed that the proposed generalized SVR model had more precisely prediction than ANN with an average absolute relative error (AARE) of 2.17%, 1.32% and 9.64% for gas holdup, downcomer liquid velocity and volumetric gas-liquid mass transfer coefficient values, respectively.
The mixing quality of the pigeon diet mix was studied after the mixing in the Ross-type static mixer (pre-mixer) and the vertical feed mixer (final mixer in the line). Three different experiments ...were performed: firstly, the possibilities of static mixer were investigated, secondly the blending performance of the vertical feed mixer, and the combination of these approaches in the third experiment. The Discrete Element Method was used in numerical modelling of granular flow in the pre-mixer and the vertical feed mixer, to predict the inter-particle mixing quality, and the results of the mixing. The results of the model were compared with appropriate experiments. The main goal was to foresee the behaviour of mixture in two type of mixers and to evaluate the combined mixing action of these two mixers, in order to explore the possibilities to increase the mixing quality, shorten the mixing time and to reduce the energy consumption.
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•Mixing of pigeon diet mix in Ross static mixer and rotating drum was investigated.•DEM was used for modelling of granular flow in these mixing devices.•The possibilities to shorten the mixing time in the main mixer were explored.•The results of numerical simulation are compared with appropriate experimental data.
In this paper, five types of horizontal single-pitch screw conveyors with modified geometry, with three different lengths (400, 600 and 800 mm) were investigated for transport and auxiliary mixing ...action of two materials: natural zeolite and quartz aggregate (sand) with particle sizes 3, 4 and 5 mm. The geometry of the screw transporter is changed by welding three additional helices oriented in the same or the opposite direction from screw cutting edges, enabling the premixing of materials, during the transport. The proper mixing of the observed materials provides an adequate disposition of zeolite particles within the composite and prevents agglomeration and interference with cement hydration. Zeolite application as a binder in a building material is a possible solution to environmental pollution problems caused by cement production. The influences of screw length, particle diameter, the studied geometry variations of screw design, on the mixing performances of the screw conveyor-mixer during material transport were explored. All investigations were performed experimentally and numerically, by using Discrete Element Method (DEM). The experimental results and the results of the DEM investigation were used for the development of mathematical models for the prediction of mixing quality, which are presented in the form of second order polynomial and artificial neural network model.
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•We did an experimental investigation for 5 types of modified screw conveyers.•DEM simulation was used for studying transport/premixing of granular particles.•The influences of screw length, particle diameter and screw geometry were observed.•The mixing performances of screw conveyor premixer during transport were explored.•The ANN model was developed for prediction of mixing quality.
The kinetic model, encompassing the curing and reversion phenomena of the NR/SBR rubber vulcanization process, was developed by means of the finite element method simultaneously with heat transfer ...equations, including heat generation due to curing reactions. The vulcanization simulation was conducted for three spheres of different diameters (1, 5 and 10 cm) and two rubber wheels, one of which was a commercial product of the rubber industry. The proposed advanced simulation model, based on products' two-dimensional axisymmetry, includes cooling after vulcanization, during which the crosslinking reactions continue to take place as a result of the products' heated interiors. As a criterion for removing the product from the mold, an average vulcanization degree of 0.9 was set, whereby, during cooling, the vulcanization degree increases, due to crosslinking reactions. Based on the minimal difference between the maximal and minimal vulcanization degrees, which did not exceed a value of 0.0142, the optimal process parameters for each product were determined, achieving homogeneity and obtaining high-quality rubber products, while simultaneously ensuring a more efficient vulcanization process and enhanced cost effectiveness for the rubber industry.
Clij ove studije bio je istraživanje hidrodinamičkih i maseno-prenosnih karatkeristika airlift reaktora sa spojnom recirkuiacijom (ELAR). ELAR je ispitan za tri slučaja: za različite ulazne brzine ...gasa. za različite rastvore alkohola (voda, 0,5% metanoi 0.5% etanoi 0,5% propanol i 0,5%> butanol) i za različite koncentracije metanola u rastvorima (0%, 0,5%, 1%, 2% i 5%). Proučavan je uticaj ulazne prividne brzine gasa i uticaj različitih vrsta razred strok signenih rastvora alkohola na hidrodinamiku i koeficijent prenosa mase gastečnost ELAR-a. Eksperimentalne vrednosti sadržaja gasa, brzine tečnosti i koeficijenta prenosa mase u ulaznoj i silaznoj ce vi su preuzete iz Iiteratum ih izvora. Razvijen je matematički model zasnovan na numeričkoj mehanici fluida (CFD). pri menjen na dvofazno strujanje, a istraživane su različite tečnosti u pogledu po vršinskog napona, pri menj uju či metodu konačnih za premi na. Eutero v-Eulero v model i jedna čine za idealan gas. Koeficijent zapreminskog prenosa mase i vrednosti za sadržaj gasa odred strok signene su CFD modelom, kao i modelom veštačke neuronske mreže. Ispitivani su uticaji parametara tečnosti i brzine gasa na karakteristike prenosa mase u sistemu gastečnost. Razvijeni modeli su u pore deni sa odgovarajućim eksperimentalnim rezultatima.
Although extensive research has been carried out on the understanding of the complex vulcanization process, the influence of reversion through exposure time and temperature on the vulcanization ...degree remains unclear. Therefore, the main aim of this study was a novel optimization approach that can help the industrial practitioners to select the optimal operating parameters, exposure time, and molding temperature, to achieve desired vulcanization degree of selected product. Spheres of four different diameters (2.5, 5, 10, and 20 cm) were selected as test geometry for simulation and optimization of rubber molding. Obtained vulcanization rheometer data for commercially available rubber blend (NR/SBR) were fitted by a new modeling approach, dividing vulcanization curve into two fitting sets: curing and reversion. The heat transfer equations for chosen geometry were coupled with proposed kinetic model. A new temperature‐dependent kinetic parameter x, as the maximal reversion degree, was introduced, enabling determination of the lowest operating molding temperature (Tmin = 132.36 °C), preventing high reversion and overheating of the rubber product. The final optimization goal was assessment of the optimal temperature and vulcanization time dependence on the rubber products dimensions. Proposed models have precise prediction with R2 values greater than 0.8328 and MAPE less than 2.3099%.
A new generation biomass-based filler for natural rubber, 'hydrochar' (HC), was obtained by hydrothermal carbonization of hardwood waste (sawdust). It was intended as a potential partial replacement ...for the traditional carbon black (CB) filler. The HC particles were found (TEM) to be much larger (and less regular) than CB: 0.5-3 µm vs. 30-60 nm, but the specific surface areas were relatively close to each other (HC: 21.4 m
/g vs. CB: 77.8 m
/g), indicating a considerable porosity of HC. The carbon content of HC was 71%, up from 46% in sawdust feed. FTIR and
C-NMR analyses indicated that HC preserved its organic character, but it strongly differs from both lignin and cellulose. Experimental rubber nanocomposites were prepared, in which the content of the combined fillers was set at 50 phr (31 wt.%), while the HC/CB ratios were varied between 40/10 and 0/50. Morphology investigations proved a fairly even distribution of HC and CB, as well as the disappearance of bubbles after vulcanization. Vulcanization rheology tests demonstrated that the HC filler does not hinder the process, but it significantly influences vulcanization chemistry, canceling scorch time on one hand and slowing down the reaction on the other. Generally, the results suggest that rubber composites in which 10-20 phr of CB are replaced by HC might be promising materials. The use of HC in the rubber industry would represent a high-tonnage application for hardwood waste.
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