Current Issue : October - December Volume : 2016 Issue Number : 4 Articles : 6 Articles
Both the estimation of the time that small heavy particles remain inside a 3D vortex and the estimation of the average settling\nvelocity of those particles are some important features in many practical situations. Previous works focused on the case of a\nhorizontal 2D vortex. In this paper, we simulate the dynamics of heavy particles initially situated inside a three-dimensional vortex\nobtaining a formula for their average settling velocity. In a previous paper we obtained the trajectories of the particles and a formula\nthat provides the time that they need to escape, ...
Catalytic pyrolysis of gas oils derived from Canadian synthetic crude oil on a kind of zeolite catalyst was conducted in a confined\nfluidized bed reactor for the production of light olefins. The overall reactants and products were classified into nine species, and\na nine-lump kinetic model was proposed to describe the reactions based on appropriate assumptions. This kinetic model had 24\nrate constants and a catalyst deactivation constant. The kinetic constants at 620âË?Ë?C, 640âË?Ë?C, 660âË?Ë?C, and 680âË?Ë?C were estimated by\nmeans of nonlinear least-square regression method. Pre exponential factors and apparent activation energies were then calculated\naccording to the Arrhenius equation. The apparent activation energies of the three feed lumps were lower than those of the\nintermediate product lumps. The nine-lump kinetic model showed good calculation precision and the calculated yields were close\nto the experimental ones....
This study focuses on performance analysis of a 1kWe microcogeneration system based on a high temperature proton exchange\nmembrane (HT-PEM) fuel cell by means of parametric investigation. A mathematical model for a system consisting of a fuel\nprocessor (steamreforming reactor andwater-gas shift reactor), aHT-PEM fuel cell stack, and the balance-of-plant components was\ndeveloped. Firstly, the fuel processor performance at different fuel ratios and equivalence ratio was examined. It is shown that high\nfuel ratios of 0.9ââ?¬â??0.95 and equivalence ratios of less than 0.56 are suitable for acceptable carbon monoxide content in the synthetic\ngas produced. Secondly, a parametric study of the system performance at different fuel and equivalence ratios using key system\noperating parameters was conducted. Steam-to-carbon ratio, stack operating temperature, and anode stoichiometry were varied\nto observe the changes in the microcogeneration system. The analysis shows that the system can reach electrical and cogeneration\nefficiencies of 30% and 84%, respectively....
This paper was focused on the investigation of a forward osmosis- (FO-) reverse osmosis (RO) hybrid process to cotreat seawater\nand impaired water from steel industry. By using this hybrid process, seawater can be diluted before desalination, hence reducing\nthe energy cost of desalination, and simultaneously contaminants present in the impaired water are prevented from migrating into\nthe product water through the FO and RO membranes. The main objective of this work was to investigate on pilot-scale system the\nperformance of the combined FO pretreatment and RO desalination hybrid system and specifically its effects on membrane fouling\nand overall solute rejection. Firstly, optimization of the pilot-scale FO process to obtain the most suitable and stable operating\nconditions for practical application was investigated. Secondly, pilot-scale RO process performance as a posttreatment to FO\nprocess was evaluated in terms of water flux and rejection.The results indicated that the salinity of seawater reduced from35000 to\n13000mg/L after 3 hrs using FOsystem, while after 6 hrs it approached 10000mg/L. Finally, FO/ROsystemwas tested on continuous\noperation for 15 hrs and it was demonstrated that no pollutant was detected neither in draw solution nor in RO permeate after the\nend of operating time....
The prediction of power generated by photovoltaic (PV) panels in different climates is of great importance.The aim of this paper is\nto predict the output power of a 3.2kWPV power plant using the MLP-ABC (multilayer perceptron-artificial bee colony) algorithm.\nExperimental data (ambient temperature, solar radiation, and relative humidity) was gathered at five-minute intervals fromTehran\nUniversity�s PVPower Plant fromSeptember 22nd, 2012, to January 14th, 2013. Following data validation, 10665 data sets, equivalent\nto 35 days, were used in the analysis. The output power was predicted using the MLP-ABC algorithm with the mean absolute\npercentage error (MAPE), the mean bias error (MBE), and correlation coefficient (...
Equilibrium and dynamic adsorption of heavy metals onto spent coffee ground (SCG) were studied.The equilibrium adsorption of\nCd2+, Cu2+, and Pb2+ in a batch system was modeled by an ion-exchange model (IEM) based on an ion-exchange of heavy metals\nwith calcium and protons bonded to active sites on SCG surface. The maximum amount of adsorbed metal ions obtained using\nthe IEM was 0.12, 0.21, and 0.32mmol/g of Cd2+, Cu2+, and Pb2+, respectively. Regeneration of SCG was evaluated using citric\nacid, calcium chloride, and nitric acid. The observed trend of desorption efficiency through four adsorption-desorption cycles\nwas HNO3 > CaCl2 > C6H8O7. The effect of process variables such as flow rate and bed height during the dynamic adsorption\nwas evaluated. Moreover, the applicability of a mass transfer model based on external mass transfer resistance, axial dispersion,\nand ion-exchange is othermwas evaluated, and the results were in good agreement with the experimental data for the adsorption in\nSCG packed column.The sensitivity analysis of the model parameters showed that axial dispersion coefficient is the most significant\nparameter in the dynamic simulation. The results obtained showed the potential of SCG as a low-cost material for waste water metal\nremoval in continuous systems....
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