Iranica Journal of Energy & Environment
Volume:4 Issue: 2, Spring 2013

In this study the effects of some different factors on ceria (CeO2) catalytic activity for ethanol steam reforming (ESR) to produce high H2/CO ratio were investigated. The considered factors were sonication time in three durations (0, 15 and 30 minutes), calcination temperature at three temperatures (500, 650 and 800°C), mole ratio of H2O/ethanol in three ratios (3, 5 and 8) and reactor temperature at three temperatures (300, 350 and 400°C). The Taguchi L9 experimental design method was used to investigate the effect of these parameters on maximization of H2/CO. To identify the catalyst characteristics XRD, SEM, EDS, BET and TGA analysis were done. It was established that a face centered cubic crystal forms of nano particles of CeO2 were formed. Also the obtained results showed that by increasing calcination temperature or reducing the sonication time, the nano particle size was increased. The reactor tests showed that the optimum conditions for maximization of H2/CO ratio were: sonication time zero, calcination temperature 800°C, H2O/ethanol ratio 3 and reactor temperature 300°C. The mole percent of H2 and CO in these conditions were 64.46 and 0.011%, respectively.

PVA (poly vinyl alcohol)-MnTiO3 (PM) and PVA-PVP (poly vinyl pyrrolidone)-MnTiO3 (PPM) nanocomposite membranes have been prepared with solutions casting method. Glutaraldehyde (GA) was used as cross linking agent. The results showed that the proton conductivity and water uptake of the nanocomposite membranes due to hydrophilic nature of MnTiO3 nanoparticles were higher than that of the PVA membrane. PPM membranes containing 5 wt. % of MnTiO3nanoparticles and PVA:PVP 80:20, demonstrated higher thermal stability, water uptake (310?) and proton conductivity (2.1 ×10 2 S/cm) than PM membranes, due to hydrophilic effect of PVP, which can made strong hydrogen-bonding, intense intra-molecular interaction and reduce the crystallinity of the PVA polymer.

Fuel cell constitutes from different components, among which bipolar plates are the important and expensive part. Nowadays, the fabrication methods of bipolar plates are the main challenges in fuel cell technology. Among different methods, the fabrication of bipolar plates from metal forming processes is the best selection. Recently, hydroforming is one of these methods that are used in fabrication of these plates. On the other hand, there are different layouts of flow fields for various usages. These layouts can be categorized, in forming viewpoint, to two distinct groups; one of them is the simple group (e.g. serpentine or parallel flow fields) and the other is the complex group (e.g. pattern and pin type flow fields). This paper investigate on feasibility of a hybrid micro-manufacturing process to fabricate fuel cell metallic bipolar plates that consists of multi-array pin type flow field on a large surface area. First, several forming methods for formation of bipolar plates in the FEM software (ABAQUS 6.10) were simulated. Second, the best method for actual fabrication of metallic bipolar plates without any rupture or defect was hydroformed. The results indicated that the complex flow field metallic bipolar plates can be formed adequately using the combined hydroforming and stamping (sizing) processes.

Polymer electrolyte membrane fuel cell stacks contain fluid flow plates, generally known as bipolar plates; which are traditionally made from graphite based materials. Brittleness of graphite enforces manufacturers to fabricate bipolar plates in great thicknesses which severely reduce the stack’s power to weight ratio. Therefore, recently the use of low permeability open pore metallic foams has been attended. This survey is focused on development of powder metallurgy method to manufacture copper foams for use as bipolar plates. After three-point flexural tests and air permeability measurements, it was shown that powder metallurgy method based on using space holder agent has high capability to produce functionally graded foams in order to substitute conventional stack fluid field plates.

In this study, a photovoltaic-electrolyser-fuel cell system was considered and simulated. This hybrid system produces hydrogen in the daytime and stores it in the storage tank in order to supply the required energy for the peak period of demand. Dynamic behavior of the process components was analyzed under different conditions. Transient simulation represents performance of the components and the system. Results can be used for improving the component’s efficiency and optimizing component’s size. The results obtained in this work, consist of hourly values of hydrogen produced by electrolyser unit, generated fuel cell energy tocover the energy demand, generated PV energy, dynamic behavior of the PEM fuel cell and tank pressure level.

Generating electrical energy for mobile applications requires specific characteristics including high energy density, high specific energy and low temperature. In this paper a Micro Zinc-Air Fuel Cell (MZAFC) has been constructed to provide the required electrical energy for small-scale vehicles. The manufactured cell provided a very smooth voltage-current characteristic curve which is very important for design purposes. The cell has been assembled and tested on a small vehicle.

Polymer Electrolyte Membrane Fuel Cells (PEMFCs) are identified as the most important choice to replace internal combustion engines. But there is still a long way to reach this fact, and, in order to reach such a purpose, it is necessary to carry out many optimizations on these cells. One of the methods resulting in a deeper and better understanding of physical processes within the cells is simulation of physical governing equations on fuel cells. In this article, these governing equations are introduced and a system of equations is solved for a model.

This study characterizes the cell performance of a proton exchange membrane fuel cell (PEMFC) considering the counter flow of hydrogen and air. The effects of porosity of anode and cathode Gas Diffusion Layers (GDL) on current density, power density and mass transfer were investigated. Half-cell model was employed for computational analysis and parallel flow was simulated for process validation. The results showed that the porosity affects the limiting current density especially in low cell voltages. Such condition is achievable in practice by diminishing the oxygen diffusion in the GDL. Also, the simulations confirmed an increase in power density by about 6 percent, when increasing the porosity of GDL by about 20 percent in the counter flow of PEMFC.

The research explained in this paper was carried out to analyze and design a point absorber wave energy convertor for Assaluyeh coastal on Persian Gulf. The geographical conditions of this region have some local short waves which may be ideal to use this type of energy convertor. According to the collecting of wave data and using an optimized buoy, it is concluded that the adjustments on damping and natural frequency have more effect on average heave displacement. Therefore, by changing the shape of flat buoy to conical cylindrical, the drag coefficient that has direct effect on the damping of the buoy could be reduced. Regarding the length to diameter ratio of 1.7 for the selected buoy, changing its shape from flat cylinder to conical cylinder causes the drag coefficient to decrease by 50 %, which is followed by 20% increase in average amplitude of heave motion from 0.524-0.625m. This increase in average amplitude heave is efficacious in increase power buoy around 45 watts.

The aim of this study is to assess the performance, emission and combustion characteristics of diesel engine using mahua methyl esters. In the present work, mahua methyl esters and its blends with diesel were used as fuel. Various proportions of mahua methyl ester fuel blends (25% and 50%) were used for conducting the performance tests at varying load conditions. Various parameters such as thermal efficiency, specific fuel consumption, emission of carbon dioxide, carbon monoxide, hydrocarbons and oxides of nitrogen gases in exhaust were recorded. The important properties of mahua methyl esters are compared with diesel standards. The test results indicate that the fuel of B25 can be used in diesel engines without any engine modifications.

Systematic industrial waste management is one of an important issue due to high environmental risks caused by improper waste disposal. Hence, present research was conducted to investigate environmental aspects of optimal disposal and management methods of industrial waste of Toos industrial estate in Mashhad. In this work, one of the environmental impact assessment methods called Rapid Impact Assessment Matrix (RIAM) was applied. Thus, various disposal options such as open dumping, sanitary landfill, gasification and incineration from the viewpoint of the physical, chemical, biological, ecological, cultural and social, economical and environmental aspects were evaluated. All of these aspects were compared due to selection of disposal methods through application of RIAM technique. The obtained results showed that sanitary landfill led to more beneficial effects than the other four mentioned options. Therefore, the best method of choice in compare to other options for waste management in the industrial estate of Toos, Mashhad was selected.

This cross-sectional study investigates the time weighted average (TWA) exposure of bakeries workers to the particulate matters concentration in the randomly selected bakeries workers. Air samples were collected from worker inhalation area in the workplaces by personal sampling method (PTFE Membrane SKC Filter with 25 mm, 2.0-μm pore sizes and SKC personal samplers pump with flow rate of 2 L/min). Filters were weighted by digital balance before and after sampling in the controlled laboratory. It was found that particulate matters concentration was higher than the National Institute of Occupational Safety and Health (NIOSH) permissible exposure limit (1mg/m). The indoor related humidity ratio (3 RH) and indoor dry bulb temperature were 65%, 32 °C, respectively. Indoor air pollution was observed in this group after consecutively controlling the effects of indoor related humidity and indoor dry bulb temperature. Due to the design of the current crosssectional nature, causal inferences cannot be made. The limitations of design and measurement are discussed in the context of the workplaces assessment field.

The Gotvand-Olya Dam is a rock-fill dam, located at Khuzestan province in southwest of Iran. Since the dam is subjected to the daily water level fluctuation, such as rapid drawdown and refill, thus induce a structural impact on the behavior of dam body, it draws many soil engineering concerns. In this paper, seepage analysis of the rock-fill dam was primarily conducted to evaluate the dam safety against the leakage through the dam body. Traditionally, steady-state analysis was employed to investigate the seepage in the dam body, summing that water level is fixed at two cases: high and low water levels. Consequently, it was not able to properly reflect the time-dependent characteristics of seepage phenomena. In this study, seepage analysis was numerically performed using 2-D FEM transient analysis. As a particular boundary condition for an analysis, the water level fluctuation was incorporated to simulate the daily changes. As a result, various seepage phenomena were quantified such as hydraulic gradient, seepage vector and pore water pressure distribution at the corresponding time of interest as the water level rises and recedes. At steady state analysis, the seepage flux at high water level in downstream area was predicted to be 78 l/s. In additions, the seepage flux measured and estimated were both acceptable considering design criteria. The result of this study proves that there is no sign of hazardous sources contributing to the possibility of piping, internal erosion and excess leakage through the dam body.

Biosurfactants are surface active compounds produced by various microorganisms. Production of biosurfactants via fermentation of immiscible wastes has the dual benefit of creating economic opportunities for manufacturers, while improving environmental health. A predictor system, recommended in such processes, must be scaled-up. Hence, four neural networks were developed for the dynamic modeling of the biosurfactant production kinetics, in presence of soybean oil or refinery wastes including acid oil, deodorizer distillate and soap stock. Each proposed feed forward neural network consists of three layers which are not fully connected. The input and output data for the training and validation of the neural network models were gathered from batch fermentation experiments. The proposed neural network models were evaluated by three statistical criteria (R2, RMSE and SE). The typical regression analysis showed high correlation coefficients greater than 0.971, demonstrating that the neural network is an excellent estimator for prediction of biosurfactant production kinetic data in a two phase liquid-liquid batch fermentation system. In addition, sensitivity analysis indicates that residual oil has the significant effect (i.e. 49%) on the biosurfactant in the process.