Chemical Engineering
M. Zamani; R. Shafaghat; B. Alizadeh Kharkeshi
Abstract
Due to the necessity of utilizing renewable energies, the Archimedes screw turbine can be used as a power generation converter for the use of hydropower energy from river flows. A laboratory-scale model of this turbine with a scale of 1:6 has been designed and constructed. In the experimental tests, ...
Read More
Due to the necessity of utilizing renewable energies, the Archimedes screw turbine can be used as a power generation converter for the use of hydropower energy from river flows. A laboratory-scale model of this turbine with a scale of 1:6 has been designed and constructed. In the experimental tests, the performance characteristics of the turbine were investigated based on variations in the flow rate and electrical resistance. The optimal flow rate for the turbine was determined with the aim of achieving maximum efficiency. The performance characteistics of the turbine at this flow rate were evaluated using empirical equations derived from the experimental tests for various parameters. These equations indicated higher values for these parameters at this flow rate. Furthermore, for the scaling of the Archimedes screw turbine, dimensionless numbers such as Froude number and flow rates ratio were introduced. The experimental results were extrapolated to the prototype scale at the optimal flow rate of 2.6 (lit/s), where the maximum turbine efficiency occurs. The results showed that the use of Froude scaling led to approximately 25% higher values for the performance characteristics of the turbine compared to scaling based on flow rates ratio.
Energy
A. Mohammadi; M. Hakimizadeh
Abstract
Gas hydrate formation is a new technology to uptake carbon dioxide. In the present work, the kinetics of changes in the volume of unreacted water, the formed carbon dioxide hydrate, and also the unreacted gas inside the reactor were investigated with the passage of time. Experiments were performed in ...
Read More
Gas hydrate formation is a new technology to uptake carbon dioxide. In the present work, the kinetics of changes in the volume of unreacted water, the formed carbon dioxide hydrate, and also the unreacted gas inside the reactor were investigated with the passage of time. Experiments were performed in a stagnant 169 cm3 double-walled reactor at a temperature of 275.15 K and a pressure of 3 MPa. The tests were done by using the isochoric-isothermal method. The results of the experiments showed that the volume of unreacted water decreased with respect to time and the volume of hydrate formed increased. Taking into account the different molar volumes of hydrate formed and the molar volume of reacted water in the test conditions, the changes in gas volume inside the reactor were calculated with the passage of time. The gas volume inside the reactor decreased from 144 cm3 at the beginning of the process to 141.62 cm3 at the end of the reaction. By decreasing the pressure during carbon dioxide hydrate formation process, the amount of hydration number increased from 6.047 mol/mol to 6.109 mol/mol.
Chemical Engineering
A. Graeeli; M. Rahimi-Esbo; V. Kord Firouzjaee; M. Sedighi; M. Rezaee Firouzjaee
Abstract
Considering the escalating significance of hydrogen production as a high-energy-density fuel, coupled with the challenges associated with its transportation and storage, the necessity to generate hydrogen at the point of consumption has become more pronounced than ever before. Thus, this research endeavors ...
Read More
Considering the escalating significance of hydrogen production as a high-energy-density fuel, coupled with the challenges associated with its transportation and storage, the necessity to generate hydrogen at the point of consumption has become more pronounced than ever before. Thus, this research endeavors to comprehensively investigate various hydrogen production processes and elucidate the merits and drawbacks of each technique. Additionally, the catalysts employed in these processes were examined, ultimately leading to the selection of methanol steam reforming using a Cu/ZnO/Al2O3 catalyst within a fixed bed reactor for hydrogen production. Subsequently, the process underwent initial simulation utilizing Aspen Plus software, enabling a close-to-reality assessment of the simulation's challenges. Following the validation of the simulation results, a comparative analysis was conducted between a reactor operating at a specified temperature (T=220℃) and a co-current reactor. Each reactor possessed distinct advantages and disadvantages. Through this comparison, it was observed that, in order to achieve the same conversion, the length of the co-current reactor could be reduced by 5.7 cm compared to the specified temperature reactor. Consequently, the construction cost was reduced; however, this modification resulted in an increased production of carbon monoxide, necessitating further investigation.
Environment
O. F. Anjorin; L. C. Imoh; C. Uhunmwangho
Abstract
Since actual metal emissions can be assessed using Particulate matter (PM) as a proxy, monitoring and controlling metal compounds in biomass emissions is essential for determining their quantities and potential health effects. Using a low volume respirable dust sampler, indoor ambient metal-bearing particles ...
Read More
Since actual metal emissions can be assessed using Particulate matter (PM) as a proxy, monitoring and controlling metal compounds in biomass emissions is essential for determining their quantities and potential health effects. Using a low volume respirable dust sampler, indoor ambient metal-bearing particles were quantified in-situ and collected from nine (9) randomly selected public kitchens of boarding secondary schools in Jos, Plateau State. Atomic absorption spectrometry (AAS) was used to determine the amounts of specific heavy metals in these collected samples. Additionally, 114 responders' blood samples underwent a biochemical lead assay study. The mean concentrations of the samples taken for Mn, Cd, Cu, Fe, Cr, Zn, Ni, Pb, and Co were 0.097, 0.015, 0.254, 0.314, 1.027, 0.000, 0.076, 0.106, and 0.169 µg/m3, respectively. The results of the blood lead assay analysis showed that 54% of the subjects had B-Pb levels above 80 µg/dL, 33% had B-Pb levels between 40 µg/dL and 80 µg/dL, 8% between 25 µg/dL and 40 µg/dL, 4% between 10 µg/dL and 25 µg/dL, 4% below 10 µg/dL, and 15% below 10 µg/dL. In general, elevated levels of metal-bearing particles in the indoor environment public kitchens expose kitchen staff to several occupational hazards.
Environment
O. O. Obiukwu; M. N. Nwigwe; T. O. Uchechukwu; J. Azubuike; D. A. Ekpechi
Abstract
Various fiber-matrix combinations were used to create biodegradable composites using sugar cane bagasse (SCB) fiber and a polyester resin (PES) matrix. SEM, FTIR, mechanical testing, thermogravimetric analysis (TGA), and the method of soil burial were employed to assess the effects of the fiber content ...
Read More
Various fiber-matrix combinations were used to create biodegradable composites using sugar cane bagasse (SCB) fiber and a polyester resin (PES) matrix. SEM, FTIR, mechanical testing, thermogravimetric analysis (TGA), and the method of soil burial were employed to assess the effects of the fiber content (9-54 wt%), PLA (1-5.5 wt%), starch (1-5.5 wt%), and fiber treatment on the morphology of the surface, flexural, thermal, tensile as well as biodegradable qualities of polyester/sugar cane bagasse fiber biocomposites. The outcomes demonstrated that the optimal tensile strength of biocomposites, impact, and Flexural capabilities were attained by the 37 wt% treated sugar cane bagasse fibers. Tensile, flexural, and impact strength measurements for the 9, 18, 27, 37, 45, and 54 wt% biocomposites, respectively, ranged from 10.21 to 18.00, 21.33 to 28.12, and 12.21 to 15.67 Mpa. The results show that sugarcane bagasse-polyester composites demonstrated acceptable mechanical and multifunctional properties. This portrays the effectiveness of Sugarcane bagasse as reinforcement for Polyester matrix and its potential for eco-friendly fabrication of components.
Fuel Cell Technology
V. Modanloo; A. Mashayekhi; B. Akhoundi
Abstract
Bipolar plates (BPPs) play an important role in PEM fuel cells in terms of weight and cost points of view. In this paper, the manufacturing of titanium BPPs with parallel flow field was experimentally and numerically studied. In this regard, a stamping die with a parallel pattern is conducted to perform ...
Read More
Bipolar plates (BPPs) play an important role in PEM fuel cells in terms of weight and cost points of view. In this paper, the manufacturing of titanium BPPs with parallel flow field was experimentally and numerically studied. In this regard, a stamping die with a parallel pattern is conducted to perform the experiments. Then, the process was modeled via the finite element (FE) simulation. By comparing simulation and experiment results, it was found that the results are in good agreement and hereupon, the accuracy of the FE model was verified. To evaluate the sheet formability, a set of FE experiments was designed through the response surface methodology (RSM). The die clearance, forming velocity, and friction coefficient were considered input parameters, and the maximum thickness reduction (MTR) of the sheet was assumed to be the output. The results revealed that a lower friction coefficient causes an increase in thickness reduction and finally tearing in the formed BPPs. Moreover, changing the forming velocity has no remarkable influence on the MTR. Afterward, an Adaptive Neuro-Fuzzy Inference System (ANFIS) was trained for predicting the output of the MTR with the three mentioned inputs.
Energy
M. Maghsoudizadeh; M. Ameri; E. Jahanshahi Javaran; A. MotamedSadr; A. A. Feili Monfared
Abstract
In recent years, the use of renewable energy sources and investigation on renewable energy have significantly grown. In this research, parabolic trough and linear Fresnel collectors, which are widely used in the field of solar energy, have been investigated from the point of view of exergy. First, the ...
Read More
In recent years, the use of renewable energy sources and investigation on renewable energy have significantly grown. In this research, parabolic trough and linear Fresnel collectors, which are widely used in the field of solar energy, have been investigated from the point of view of exergy. First, the energy balance equations for different components of the collector were solved using numerical methods and the temperature distribution in each component of the collector was obtained. Then the values of exergy destruction in each component of the system were calculated. The comparison of the results obtained in the present work with the results of the previous research showed a good agreement. The results showed that the exergy efficiency in the parabolic trough collector is approximately 1.5 times that of the linear Fresnel reflector. Also, changes in exergy efficiency, exergy destruction of the whole collector, output exergy cost and CO2 emission with increasing solar radiation intensity and fluid mass flow rate for both collectors have been compared and investigated.
Energy
N. Momen; H. Pahlavanzadeh
Abstract
Nowadays, due to environmental concerns and the reduction in fossil fuel resources, biodiesel is being considered as a renewable alternative or supplement to fossil diesel. In this research, the transesterification method was used to produce biodiesel from low-cost and non-edible linseed oil in the presence ...
Read More
Nowadays, due to environmental concerns and the reduction in fossil fuel resources, biodiesel is being considered as a renewable alternative or supplement to fossil diesel. In this research, the transesterification method was used to produce biodiesel from low-cost and non-edible linseed oil in the presence of commercial calcium oxide as the catalyst. In addition, the time-consuming and costly calcination step was omitted and a deep eutectic co-solvent of choline chloride/glycerol (2:1) was used to activate the catalyst. The catalyst characterization was studied using X-ray diffraction(XRD) and Fourier transform infrared (FTIR). To ensure the formation of fatty acid methyl esters (FAME), the purity of FAME in the produced biodiesel was calculated using gas chromatography method. Then, the effect of two reaction parameters of the catalyst and the DES concentration on the FAME purity was investigated at a constant temperature of 65 °C, stirring speed of 500 rpm, reaction time of 180 minutes and the methanol to oil molar ratio of 9.5:1. Finally, the optimal catalyst and the DES concentration were obtained as 10% and 14%, respectively. The effect of temperature and time on the FAME purity was investigated and a kinetic study of the reaction suggested a pseudo-first-order reaction with a rate constant of 0.0311 at 65 °C and activation energy of 22.45 kJ/mol.
Energy
N. Hedayati Goodarzi; M. Rahimi-Esbo
Abstract
Steam reformers are typically utilized in hydrogen production industry, demanding pressure vessels within methanol reformer systems operating at temperatures between 250-350°C to ensure cost-effectiveness. This characteristic makes them a superior choice for fuel cell systems. However, challenges ...
Read More
Steam reformers are typically utilized in hydrogen production industry, demanding pressure vessels within methanol reformer systems operating at temperatures between 250-350°C to ensure cost-effectiveness. This characteristic makes them a superior choice for fuel cell systems. However, challenges arise in enhancing hydrogen gas production efficiency while minimizing carbon monoxide emissions. Computational Fluid Dynamics (CFD) has proven effective in addressing these challenges by simulating fluid behavior. This study delves into product production, reactant consumption using CFD, and investigates changes in physical parameters of methanol reformers to optimize their performance. The research involves 140 numerical simulations that examine the relationship between feeds (steam-to-carbon) and various temperatures, aiming to understand the concurrent effect of physical parameters. The results demonstrate that increasing temperature has a more significant impact on hydrogen production compared to increasing the feed ratio. This effect is particularly notable at lower fuel ratios. For example, at a feed ratio of 1, a temperature increase of 11.4°C leads to a substantial 5.4% rise in hydrogen production. However, at a higher feed ratio (1.98), the increase in hydrogen production is only 1.9% with the same temperature increase.
Environment
A. Yousefi Kebriya; M. Nadi
Abstract
The Air Quality Index is a numerical tool used to quantify air pollution levels and classify pollution severity. It plays a vital role in ensuring healthcare system stability by understanding air pollution's dynamic behavior and shifts in pollution intensity. To analyze the probabilistic transition between ...
Read More
The Air Quality Index is a numerical tool used to quantify air pollution levels and classify pollution severity. It plays a vital role in ensuring healthcare system stability by understanding air pollution's dynamic behavior and shifts in pollution intensity. To analyze the probabilistic transition between pollution severity levels, a Markov Chain model was utilized. This study examined six air pollution states (Clean, Healthy, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, Hazardous) across 12 stations in Tehran's northern, southern, eastern, western, and central regions from 2018 to 2022. Results revealed that the western and southern areas exhibited the highest pollution levels, with over 44% and 34% of instances corresponding to unhealthy indices, respectively. In contrast, northern Tehran consistently maintained cleaner air quality. Probability transition matrices highlighted the greatest stability continuity in healthy air quality across all regions. Transitioning between clean/healthy air to very unhealthy/hazardous air was minimal, with hazardous air quality almost absent in most stations, except for the west and south (25% stability). The probability of continued unhealthy air quality in these areas reached 60%, indicating heightened pollution. The findings of transition probability matrices indicated that the western and southern regions had the highest likelihood of sustained pollution, while the northern region consistently maintained cleaner air. The probability of continuous clean air in the west was below 30%, while transitioning from very unhealthy/hazardous air to unhealthy air reached 50%. Conversely, the northern Tehran region exhibited over 40% stability for unhealthy air quality and over 50% for clean and healthy air.
Mass Transfer
A. Bagheri; S. Karimian Aliabadi; K. Ghaemi Osgouie; M. Shafaee
Abstract
In this experimental work, the 2-phase air-water non-boiling ascending fluid flow in a vertical tube with helical corrugations has been investigated. The results showed that the head loss values decreased with an increase of the volume fraction. Also, by comparing the head loss values for each corrugation ...
Read More
In this experimental work, the 2-phase air-water non-boiling ascending fluid flow in a vertical tube with helical corrugations has been investigated. The results showed that the head loss values decreased with an increase of the volume fraction. Also, by comparing the head loss values for each corrugation pitch, it can be observed that as the corrugation pitch goes down, the head loss values significantly increase. As a result, the intensity of vapors increases perpendicular to the main flow of water, which leads to an increase in the intensity of disturbance in the flow, and then the head loss increases. The Nusselt number goes down when the volume fraction experiences an increment. Looking at the figures related to Nusselt number, it is easy to see that the curves are drawn for a constant air flow rate. Consequently, an increase in volume fraction (VF) is equal to a decrease in the water flow rate. By reducing the water flow rate, the intensity of the main flow is reduced the intensity of turbulence is also reduced and the heat transfer coefficient is reduced. As a result, the amount of heat transfer has increased due to air injection. It should be noted that pipes with the largest corrugation pitch had the best Cost-benefit ratio (C.B.R.) factor values (which means the lowest value). This means that air injection in larger corrugation pitch tubes was more beneficial than in smaller corrugation pitch tubes.
