Gholamreza Zahedi

Strategies for the consolidation of biologically mediated events in the conversion of pre-treated lignocellulose into ethanol

Notwithstanding the plentiful published work on the production of ethanol from lignocellulosic materials this comprehensive review relates how the basic research of a commercially viable industrial production strategy is still lacking. The objective of this review is to compile information on the different strategies and to consolidate the biologically mediated events involved in the conversion of pre-treated lignocellulose to ethanol and associated expenses so that some generalized information can be developed that could help policy makers and other stakeholders in designing a policy framework to promote second generation biofuels. The review also discusses the potential of process integration, its cost competitiveness and role in establishing commercial facilities for the production of ethanol from lignocellulosic biomass.

Optimization of biodiesel production from waste cooking oil using ion-exchange resins

Waste cooking oil is a potential alternative of refined vegetable oil for biodiesel production due to its low cost and elimination of its disposal problem. The concentration of free fatty acids (FFAs) in WCO dictates the type of chemical treatment required for biodiesel production: a single esterification reaction is considered at high content of FFAs, whereas, a combination of estrification and transestrification reaction is used at moderate content of FFAs. In this study, optimization of esterification process of FFAs in artificially acidified soybean oil with oleic acid combined with methanol as an agent and ion exchange resin as a heterogeneous catalyst was carried out. The optimization process was performed by means of Matlab software based on a kinetic model available in the literature. Conversion of acidified oil was determined as an objective function in correlation with reaction variables i.e., temperature and catalyst weight. It is found that the maximum conversion of the free acids is 95.95% which is achievable at 4.48 g catalyst loading and reaction temperature of 120°C.

Estimation of the effect of biomass moisture content on the direct combustion of sugarcane bagasse in boilers

Many of the large-scale biomass combustion systems for producing heat, hot water, or steam accept biomass fuels containing relatively large amounts of moisture. Dry biomass burns at higher temperatures and thermal efficiencies than wet biomass. Flame temperature is directly related to the amount of heat necessary to evaporate the moisture contained in the biomass, the lower the moisture content, the lower the amount of energy needed to remove the water and the higher the boiler efficiency. In this article, a simple predictive tool is developed to estimate boiler efficiency as a function of stack gas temperature and sugarcane bagasse moisture content. The method quantitatively illustrates the effect of moisture content on the performance of a thermochemical process, for the direct combustion of sugarcane bagasse in a conventional boiler. The results are found to be in excellent agreement with reported data in the literature with average absolute deviation being around 1%. The tool developed in this study can be of immense practical value for engineers to have a quick check on biomass moisture content on the boiler performance at various conditions without opting for any experimental trials. In particular, engineers would find the approach to be user-friendly with transparent calculations involving no complex expressions.

Application of Social Cognitive Career Theory to Investigate the Effective Factors of the Career Decision-Making Intention in Iranian Agriculture Students by Using ANN

The main purpose of this study was to determine the factors that affect the career decision-making intention of agriculture students of Kermanshah University based on Social Cognitive Career Theory (SCCT), by using Artificial Neural Network (ANN). The research population included agriculture students (N = 1,122). Using stratified random sampling, a sample of 288 was constituted. Data were collected using a questionnaire, which consisted of four parts: Career Decision-Making Self-Efficacy (CDMSE), Career Decision-Making Outcome Expectation (CDMOE ), Career Exploratory Plans or Intentions (CEPI), and NEO Five Factor Inventory (NEO-FFI). Back translation was used for validity, and reliability was assessed using Cronbach’s alpha coefficient. To analyze the data, statistical methods and ANN with MATLAB software were used. On the basis of trial and error, a network, including three layers with one hidden layer with 20 neurons, Levenberg–Marquardt training algorithm, and sigmoidal transfer functions, was selected to construct the network of career decision-making intention. After training and simulation, the validation of the network was tested by linear regression (R = .999). For assurance of the generalization, the network was tested again. Finally, analysis of variance was used to compare the network output.

A new method estimates TEG purity versus reconcentrator temperature at different levels of pressure in gas dehydration systems

There are several processes and principles for obtaining high triethylene glycol (TEG) purity in gas dehydration process. All methods are based on the principle of reducing the effective partial pressure of water in the vapour space of the glycol reboiler, and hence obtaining a higher glycol concentration at the same temperature. One of the most common methods for enhancement of the glycol concentration has been by means of pressure reduction in the reboiler. In this article a simple method is developed to estimate TEG purity as a function of reconcentrator (reboiler) temperature and pressure. The results are found to be in excellent agreement with reported data in the literature with average absolute deviation being around 0.05%. The tool developed in this study can be of immense practical value for engineers to have a quick check on TEG purity as a function of reconcentrator (reboiler) temperature and pressure at various conditions without opting for any experimental trials. In particular, engineers would find the approach to be user-friendly with transparent calculations involving no complex expressions.

Optimization of biodiesel production from waste cooking oil using ion exchange resins

Waste cooking oil is a potential alternative of refined vegetable oil for biodiesel production due to its low cost and elimination of its disposal problem. The concentration of free fatty acids (FFAs) in WCO dictates the type of chemical treatment required for biodiesel production: a single esterification reaction is considered at high content of FFAs, whereas, a combination of estrification and transestrification reaction is used at moderate content of FFAs. In this study, optimization of esterification process of FFAs in artificially acidified soybean oil with oleic acid combined with methanol as an agent and ion exchange resin as a heterogeneous catalyst was carried out. The optimization process was performed by means of Matlab software based on a kinetic model available in the literature. Conversion of acidified oil was determined as an objective function in correlation with reaction variables i.e., temperature and catalyst weight. It is found that the maximum conversion of the free acids is 95.95% which is achievable at 4.48 g catalyst loading and reaction temperature of 120°C.

Estimation of the depth of frost penetration in both uniform and layered soils in frost-affected regions

One of the most important factors affecting pavement performance is climate, including frost action and precipitation. The performance of pavements in frost-affected regions depends to a large degree on the depth of frost penetration. In this paper, a simple predictive tool is developed to calculate a new correction coefficient depending upon the thermal ratio and fusion parameter. The new correction coefficient can be used in follow-up calculations to estimate the depth of frost penetration for both uniform and layered soils in frost-affected regions to evaluate the performance of pavement. The results of the proposed method are found to be in excellent agreement with reported data in the literature with average absolute deviation being less than 0.8%. The predictive tool is simple, straightforward and can be readily implemented in any standard spreadsheet programme leading to accurate, smooth and non-oscillatory data points. The prime application of the method is as a quick-and-easy evaluation tool in conceptual development and scoping studies in which the depth of frost penetration for both uniform and layered soils in frost-affected regions is being considered. The method may also serve as a benchmark in numerical and rigorous simulation studies.

A novel method to estimate the specific gravity and refractive index of seawater

AbstractSeawater is described by a number of physical and chemical parameters that are useful in measurement and analysis of materiel effects. The material dissolved in seawater will not only affect its specific gravity, but also its optical properties, or rather, the degree to which light is refracted as it passes through the sample of water. The specific gravity and refractive index of seawater are related directly to salinity and temperature. In this work, an attempt has been made to develop simple predictive tools to estimate specific gravity and refractive index of seawater as a function of salinity and temperature. Estimations are found to be in excellent agreement with reported data in the literature with average absolute deviation being less than 0.2%.The predictive tool developed in this study can be of immense practical value for engineers to have a quick estimate on the specific gravity and refractive index of seawater without opting for any experimental trials. In particular, process and water...

Embedding Methane Steam Reformer and Methanol Reactor into a Single Reactor

Non-incremental reductions in process plant size, cost reduction, safety, environment, and energy are some of the major objectives that currently drive the process industry towards intensifying the existing and future installations. In the present study, direct coupling of methane steam reformer and methanol reactor has been proposed. The synthesis gas produced in reformer was directly fed to methanol reactor skipping secondary reformer and shift convertors. A heterogeneous steam reformer model was developed and embedded with heterogeneous methanol reactor model. The set of differential algebraic equations was solved in MATLAB. Steady state and dynamic simulation results were validated against real plant data. The results showed gradual increase in the methanol mole fraction along the reactor length with a simultaneous decrease in CO and CO2 levels. Although, the methanol yield achieved through this new reactor scheme remained unchanged, but the reduction in number of equipment and heat integration may help lower operational and capital cost and overall energy demand of the plant.

Hydrodynamic and heat transfer modeling of polydisperse fluidized bed olefin polymerization reactors

A computational fluid dynamics model was coupled with population balance model (CFD-PBM) to investigate hydrodynamic and heat transfer phenomena in an ethylene polymerization reactor. A gas-solid multiphase flow was developed based on the Eulerian-Eulerian approach. The polymer particle size distribution (PSD) is represented by four node using the quadrature method of moment (QMOM). The model was used to study segregation& mixing, pressure drop, bed height and that to compute particles temperature and hot spots in the gas phase reactor. Results of simulation were validated with real industrial ethylene polymerization plant data. Result showed that not much segregation was observed and the particle size diameter remains constant in the bed. However, the fine polymer particles tend to move toward the top of the reactor. The small particles were likely to have high temperature, due to the high activity, and thus hot spots observed in the top the bed.