Current Issue : April - June Volume : 2014 Issue Number : 2 Articles : 6 Articles
The computational fluid dynamics modeling of solid particles hydrodynamic based on the Lagrangian framework for diluted solidgas\r\nflow through 90�° gas pipeline bend is carried out to discover the effect of particles size distribution on particles flow pattern\r\nand their erosive effect on the bend. Particles size distribution has been obtained experimentally by measuring the sizes of solid\r\nparticles that are flowing through the gas pipelines of Aghajari gas booster station. Also the erosion rate at the outer wall of the bend\r\nis predicted. The pipeline bend under study has a pipe diameter of 56 inches and ratios of the bend radius of the curvature to the\r\npipeline diameter of 1.5. For the validation of computational model, firstly, the computationalmodeling is performed for a published\r\nexperimental solid-gas flow data.Thecomputational results include radial gas velocity and radial particle velocity profiles on planes\r\nwhich are at different angles through the bend.The comparison between the predicted numerical results and similar experimental\r\ndata proves that the predictions of the computational model are acceptable. Finally, the particlesâ�� size distributions on each plane\r\nthrough the bend and the erosion rate on the outer wall of the bend have been obtained. The maximum rate of erosion is found to\r\nbe 3.2 nm/s, occurring between 40 and 65�° of the bend...
This work investigates the production of free fatty acids (FFAs) from the enzymatic hydrolysis of macauba kernel oil. Experiments\r\nevaluate the effect of different enzymes and the addition of salts, surfactants, and solvents to the reaction medium, as well as the\r\neffect of process variables. Results showed that FFA yields obtained for use of Lipozyme RM IM were higher than those obtained\r\nfrom Lipozyme TL IM and Lipozyme 435. The addition of salts and surfactants did not promote increased production of FFAs,\r\nwhile adding n-hexane and heptane to the reaction medium led to an increased reaction rate. It can be observed for the results that\r\nthe temperature, water : oil mass ratio, and enzyme percentage had positive effects on the FFA yield in the range of 35�°C to 55�°C,\r\n1 : 20 to 1 : 2, and 1 to 15%, respectively, and that, from these limits, increases in these variables did not cause significant increase in\r\nFFA yields. The addition of buffer promoted an increase in yield FFAs, as well as the pH of the buffer, and it was reported that an\r\nagitation of 400 rpm resulted in the highest yields in the investigated range....
Chemical-looping with oxygen uncoupling (CLOU) is a novel combustion technology with inherent separation of carbon dioxide.\r\nTheprocess is a three-step process which utilizes a circulating oxygen carrier to transfer oxygen fromthe combustion air to the fuel.\r\nThe process utilizes two interconnected fluidized bed reactors, an air reactor and a fuel reactor. In the fuel reactor, the metal oxide\r\ndecomposes with the release of gas phase oxygen (step 1), which reacts directly with the fuel through normal combustion (step\r\n2). The reduced oxygen carrier is then transported to the air reactor where it reacts with the oxygen in the air (step 3). The outlet\r\nfrom the fuel reactor consists of only CO2 and H2O, and pure carbon dioxide can be obtained by simple condensation of the steam.\r\nThis paper gives an overview of the research conducted around the CLOU process, including (i) a thermodynamic evaluation, (ii)\r\na complete review of tested oxygen carriers, (iii) review of kinetic data of reduction and oxidation, and (iv) evaluation of design\r\ncriteria. From the tests of various fuels in continuous chemical-looping units utilizing CLOU materials, it can be established that\r\nalmost full conversion of the fuel can be obtained for gaseous, liquid, and solid fuels....
The low solubility in common solvent and high viscosity resulting from its high molecular weight (MW) with fiber-like structure\r\nprevents a more widespread use of chitosan. This paper presents a performance comparison of nonspecific, commercially available\r\nenzymes, ??- and ??-amylases, for the hydrolysis of chitosan to lower its MW. The results showed that both enzymes demonstrate\r\nthe ability to be used as catalysts in chitosan hydrolysis with ??-amylase having better performance than ??-amylase. The chitosan\r\nhydrolysis was influenced by not only the enzyme and the chitosan characteristics but also the hydrolysis condition.The optimum\r\npH solution was 4 for ??-amylase and 5 for ??-amylase.The hydrolysis temperature was found to be optimal at 90 and 50�°C for ??-\r\nand ??-amylases, respectively....
Artificial neural network (ANN) technique has been applied for estimation of vapor-liquid equilibria (VLE) for eight binary\r\nrefrigerant systems. The refrigerants include difluoromethane (R32), propane (R290), 1,1-difluoroethane (R152a), hexafluoroethane\r\n(R116), decafluorobutane (R610), 2,2-dichloro-1,1,1-trifluoroethane (R123), 1-chloro-1,2,2,2-tetrafluoroethane (R124), and 1,1,1,2-\r\ntetrafluoroethane (R134a). The related experimental data of open literature have been used to construct the model. Furthermore,\r\nsome new experimental data (not applied in ANN training) have been used to examine the reliability of the model. The results\r\nconfirm that there is a reasonable conformity between the predicted values and the experimental data. Additionally, the ability\r\nof the ANN model is examined by comparison with the conventional thermodynamic models. Moreover, the presented model is\r\ncapable of predicting the azeotropic condition....
The bulk properties of coal were detected and evaluated in a trial to offer an electric print or feature of the Egyptian coal at the different states of frequencies and saturations to facilitate a TOC and S2 evaluation by a rapid and cheap electric method. In the present study, the electric print; is a term used to match the electric behaviour of the coal samples represented as electric resistivity (R) against the used current frequency (f). The coal samples were then analyzed to estimate the total organic carbon content (TOC) and Rock-Eval pyrolysis. The results reveal that, the coal samples of Safa Formation consist of mixed type II/III kerogen with very good source rock of high-level maturity properties. This indicates that the Jurassic coal of Safa Formation from Gebel El Maghara in North Sinai have oil and gas prone coals and also, indicates that do not generate one type of oil but instead the character of oils will be variable. The most strongly oil prone coals analyzed here would be expected to generate waxy oils. The measured electric resistivity values, on the other hand, have a good contribution from the TOC of Safa samples, so it was possible to calculate the TOC in terms of R at the different frequencies in the dry state....
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