Energy
P. A. Ayoubi; M. E. Yazdi; I. Harsini
Abstract
The development of models that predict power production of wind farms (WFs) by considering the interacting wakes is important; because wakes of the turbines exert a significant influence on power production of turbines, and hence on the layout of wind turbines in WFs. Thus, the purpose of present study ...
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The development of models that predict power production of wind farms (WFs) by considering the interacting wakes is important; because wakes of the turbines exert a significant influence on power production of turbines, and hence on the layout of wind turbines in WFs. Thus, the purpose of present study was to provide an innovative analytical method for the prediction of power generation of the WFs that have a flat terrain and are consisted of horizontal-axis wind turbines (HAWTs) with the same hub height. The methodology employed utilized an analytical Gaussian model of HAWT wake to develop an analytical model that calculates the effective wind velocity acting on the downstream HAWT(s), which is further used for reading its generated power from the turbine’s catalog; thus, providing the generated power of the WF as the output. The results of presented model were validated by the field measurements data of Horns Rev WF and also were compared to two analytical models for predicting the generated power. The results were compared with two numerical simulations of the literature, and the output data of three commercial software. Moreover, the error analysis revealed that the presented model mostly showed superior accuracy in predicting the field measurements data.
Renewable Energy
S. M. Seyed Hoseini; A. Mohammadzadeh; M. Seighli; F. Rezaei
Abstract
With the increase in world population and limited energy resources, countries have faced the high demand of energy and energy consumption problem. The crisis that threaten countries and human societies are the limited resources of non-renewable (fossil) energy and the increase in environmental pollution ...
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With the increase in world population and limited energy resources, countries have faced the high demand of energy and energy consumption problem. The crisis that threaten countries and human societies are the limited resources of non-renewable (fossil) energy and the increase in environmental pollution caused by excessive consumption of fossil fuels and global warming. These factors have motivated researchers and investors in the energy sector to control and supply energy from renewable sources. The uncertainty caused by these generations can have many effects on the costs imposed on the network and the operation of the electricity networks, such as an increase in power outages and unsupplied energy. Network development planning is one of the important issues in the power system to meet the growth of electricity demand in the coming years due to urban development, increasing social welfare, energy security, and job creation. The final objective of this model is to minimize energy losses, investment and operating costs, unsupplied energy, and environmental pollutants. The proposed methods have been implemented by MATLAB software on the Garver electricity network and the IEEE 33-bus distribution network and solved by PSO algorithms. The final model can be effectively used for planning the supply chain of the conventional electricity network with the penetration of renewable energy-based generations in various economic, environmental, and social dimensions.
Energy
O. E. Olabode; I. K. Okakwu; D. O. Akinyele; T. O. Ajewole; S. Oyelami; O. V. Olisa
Abstract
The impact of solar radiation and ambient temperature on solar PV energy yield and its corresponding economic implication was investigated. The electrical load assessment was done by physical inspection through periodic visits to study location. Five different scenarios were investigated for two locations ...
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The impact of solar radiation and ambient temperature on solar PV energy yield and its corresponding economic implication was investigated. The electrical load assessment was done by physical inspection through periodic visits to study location. Five different scenarios were investigated for two locations - Ogun and Bayelsa States: Case I considers the PV performance based on the locations’ historical solar radiation and temperature data, Case II considers 30 % increase in the solar radiation data while the ambient temperature data remains fixed, Case III focuses on when solar radiation data is decreased by 30 % while the ambient temperature data remains constant, Case IV considers the solar radiation data remains constant while the temperature values are increased by 30 %, and Case V examined the same solar radiation values with temperature data values being decreased by 30 %. The HOMER pro was used as the implementation tool, Electrical energy yield, Unmet electric load, Net present cost, Levelized cost, and Operating cost for Cases I, II, III, IV, and V in Ota, Ogun State were as follows: 28,659 kWh/y, 4.71kWh/y, $13,537, $0.166, 271.43kWh/y; 37,260 kWh/y, 1.63kWh/y, $12,417, $0.152, 290.43kWh/y; 20,058kWh/y, 3.22kWh/y, $15,663, $0.192, 293.14kWh/y; 28,659kWh/y, 4.71kWh/y, $13,537, $0.166, 271.43kWh/y; and 28,659kWh/y, 4.61kWh/y, $13,437, $0.156, 261.43kWh/y, respectively while similar trend was observed for Otuasega in Bayelsa State. The results of the analysis showed that the optimal performance of the PV module occurred at a higher solar radiation and a lower ambient temperature.
Environment
O. F. Anjorin; L. C. Imoh; C. Uhunmwangho
Abstract
Biomass use in small unit combustion systems such as for space heating or cooking could lead to ineffective mixing and potential problems arising from emissions of gaseous and particulate pollutants. We therefore conducted a study to measure pollution levels in public kitchens using biomass fuel for ...
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Biomass use in small unit combustion systems such as for space heating or cooking could lead to ineffective mixing and potential problems arising from emissions of gaseous and particulate pollutants. We therefore conducted a study to measure pollution levels in public kitchens using biomass fuel for cooking and to ascertain their air quality indices. Markers of indoor air quality such as CO, SO2, H2S, PM2.5 and PM10 were measured in eleven (11) public kitchens of selected secondary schools over a period of four months by a set of active sampling devices. It is revealed that the mean average of CO, SO2, H2S, PM2.5 and PM10 sampled in the indoor microenvironments of the selected kitchens are 46.29 ppm, 0.36 ppm, 0.28 ppm, 74 µg/m3 and 138 µg/m3, respectively. The AQI assessed for CO for the kitchens was 36.36% very hazardous, 54.54 % hazardous and 9.09% very unhealthy while 63.64% and 36.36 % of very unhealthy and unhealthy categories, respectively for SO2. This shows that the indoor air pollution levels in selected kitchen are elevated and results in potential negative health consequences.
Energy
A. Amini; N. M. Nouri; S. Niazi; A. Abedi
Abstract
Surface-piercing propellers (SPP) are known as one of the most efficient propellers in marine sciences and maritime industries. In this study, different types of simulations were performed on an SPP in various rotational speeds in open water conditions, and a numerical study was also carried out on a ...
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Surface-piercing propellers (SPP) are known as one of the most efficient propellers in marine sciences and maritime industries. In this study, different types of simulations were performed on an SPP in various rotational speeds in open water conditions, and a numerical study was also carried out on a particular type of such propellers. In fact the main purpose of this paper is comparing the simulation results with the experimental results from past in order to derive a trustable soultion for future works. For this purpose, the surface-piercing propeller was simulated by OpenFoam software (an open source software with high range of capabilities) in order to analyze the results. The performance curve was then plotted and compared with the ones from open water tests. In this case the turbulance model of K-Epsilon RNG was used which is capable of increasing Y+ to 300 which is monitored at the end of the simulation with the maximum amount of 315 and the average of 80. Results showed that the curves followed the same pattern and trends in the numerical study, and the report pointed to similar findings. In conclusion, it was proved that the sliding mesh method was a proper way for simulating propellers, particularly SPPs. The curves for thrust and torque coefficients of the SPP were also compared with the literature and the efficiency curve was plotted.
Water Resources Engineering
S. N. Motevalian; M. R. Majdzadeh Tabatabai
Abstract
The aim of present study was to investigate the relationship between hydraulic and ecological variables of the studied span and to investigate changes in living conditions of phytoplankton (Amphora ovsalis and Navicula placentula). According to the measurements and analysis of habitat fit curves, it ...
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The aim of present study was to investigate the relationship between hydraulic and ecological variables of the studied span and to investigate changes in living conditions of phytoplankton (Amphora ovsalis and Navicula placentula). According to the measurements and analysis of habitat fit curves, it can be concluded that the highest frequency of Amphora ovsalis and Navicula placentula occurred and specified at flow rate of 15.82 and 14.942 m3/s, respectively. As can be seen, the lowest frequency of Amphora ovsalis and Navicula placentula in this measurement occurred at flow rate of 15.355 and 5.289 m3/s, respectively. The best habitat conditions for Amphora ovsalis and Navicula placentula are in the range of 0.18 -0.31 and 0.18 - 0.265 of Froude number range respectively. The highest density and abundance of Amphora ovsalis and Navicula placentula was observed in the range of 0.017 - 0.055 and 0.017 -0.039 mg/l of phosphate demonstrating that the best growth and living conditions are predisposed in this range for these species had suitable habitat conditions for life in this range. The highest frequency of Amphora ovsalis and Navicula placentula is in the range of 0.019 - 0.071 and 0.047-0.071 mg/l nitrite, respectively. Amphora ovsalis and Navicula placentula had the highest frequency when nitrate ranges 4.48 – 5.16 and 4.48- 5.37 mg/l. The best habitat conditions for Amphora ovsalis and Navicula placentula were between the mean velocity values in the range of 1 -1.2 m/s.
Environment
O. O. Obiukwu; M. N. Nwigwe; T. O. Uchechukwu; J. Azubuike; D. A. Ekpechi
Abstract
The experimental study of the physicochemical properties of biodegradable composite of sugarcane bagasse-polyester have been investigated. Natural composite materials having biodegradable property which makes them a material with limited lifespan, thereby there is a need to research on these materials ...
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The experimental study of the physicochemical properties of biodegradable composite of sugarcane bagasse-polyester have been investigated. Natural composite materials having biodegradable property which makes them a material with limited lifespan, thereby there is a need to research on these materials beyond their normal scope before their lifespan for solid material applications as current technological concepts advances. In this research, water absorption, specific gravity, and chemical resistance test were conducted on sugarcane bagasse polyester composite of different specimen, using a laboratory beaker filled with distilled water, HCl, NaOH, H2O2, NaOCl and detergent solution, at a particular time observing a suitable ASTM. From the result obtained, specimen with 25 weights % increase in Sugarcane bagasse fibre loading, indicated water absorption value of 1.42 %, which could be acceptable for good resistance to water material. The chemical resistance test, severity of the attack and effect on the appearance and weight of the composites followed the order: 10% HCl > 10% NaOH solutions, the deteriorating effect of the composites showed to be unaffected by neither the amount of filler weight nor the presence of any additive incorporated in the SCB-PES composites.
Energy
S. Abbasi; S. Esmailzadeh Vali
Abstract
In this study, the simultaneous effect of suction and blowing on the boundary layer and the effect of control parameters on the flow separation from a NACA 0012 airfoil is numerically analyzed. Reynolds number is considered 500000 , and the shear stress transport (SST) k-w turbulence model is used to ...
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In this study, the simultaneous effect of suction and blowing on the boundary layer and the effect of control parameters on the flow separation from a NACA 0012 airfoil is numerically analyzed. Reynolds number is considered 500000 , and the shear stress transport (SST) k-w turbulence model is used to estimate eddy viscosity. The airfoil is supposed to be 2-D. To validate the numerical results, they were compared with reported experiments. In the flow control by simultaneous suction and blowing, the location of the suction jet was 0.1 of the airfoil chord from the fixed leading edge, and that of the blowing jet was 0.5, 0.7, and 0.9 of the airfoil chord from the leading edge. When the blowing location is at 0.5 of the airfoil chord, better results are observed than I n; other locations. An increase in suction jet velocity increases the lift-drag ratio between 22% and 55%. Also, increasing the blowing jet velocity increases this ratio between 43% and 55%. Horizontal blowing has the most negligible effect on improving aerodynamic characteristics. Based on the results, at the angle of attack of 16°, blowing is most effective in the flow control at with an approximate velocity of half the free stream velocity. In this condition, vertical suction has the best effect , and the lift-drag ratio will increase by 76%.
Energy
M. Jahangiri; O. Nematollahi; H. Saghaei; A. Haghani
Abstract
Providing sustainable energy to achieve favorable economic development has attracted the attention of many governments in recent years. Renewable energies, especially wind energy, have gained considerable media attention recently due to challenges with the use of fossil fuels, including difficulty in ...
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Providing sustainable energy to achieve favorable economic development has attracted the attention of many governments in recent years. Renewable energies, especially wind energy, have gained considerable media attention recently due to challenges with the use of fossil fuels, including difficulty in accessing and devastating environmental impacts. Extensive efforts have been made in Asia to benefit wind energy regionally, all of which have made Asia a leader in this field. There are a few simulation results in this area, given the importance and need to compile infrastructural strategies and programs that require a thorough understanding of the current state of wind energy usage and determining its potential in different regions. Therefore, this study reports for the first time on surveys conducted on average of 20-year wind speed data collected from 2892 stations in 49 Asian countries and wind speed and power density maps obtained using Geographic Information System (GIS) software and the Boolean method. Besides assessing the problems and issues of energy consumption in countries with high potential wind energy in Asia, in this paper, we try to explore the benefits and requirements of using wind energy in these countries as well as the possibility of maximally using wind energy. According to the results, east and north of Russia, as well as west and southwest Asia are optimal regions for establishing large-scale wind plants; there is no significant potential for the use of wind energy in other regions, especially in the majority of China, ASEAN countries, and their neighboring countries.
Environment
A. C. Johnson
Abstract
The COVID-19 pandemic, which began during early 2020, had been a worldwide problem, resulting in significant fatalities. In China, the pandemic resulted in strict lockdowns, restricted movement, and reduced transportation. This resulted in improvement of air quality in many cities in China. The objective ...
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The COVID-19 pandemic, which began during early 2020, had been a worldwide problem, resulting in significant fatalities. In China, the pandemic resulted in strict lockdowns, restricted movement, and reduced transportation. This resulted in improvement of air quality in many cities in China. The objective of the study is to compare the nature of air quality pre-COVID period (2018-2019) and during COVID period (2020-2201). The following air quality parameters were investigated, air quality index (AQI), particulate matter (PM2.5 and PM10), sulphur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), and carbon monoxide (CO). The present investigation results will augment to the current understanding on the air pollution situation during the COVID-19 pandemic in Jiangsu Province in China. The study revealed that air quality in Jiangsu Province improved during the months when COVID-19 positive cases increased. The reduction in air pollutants concentrations started during 2020 and reached a maximum during 2021. Overall the air quality index (AQI) improved by 8.2 % and air pollutant reductions achieved were, PMs (≈ 21%), SO2 (26.2 %), NO2 (13.6 %), O3 (2.4 %) and CO (10.4 %). Cities in Jiangsu Province with high air pollutant concentrations achieved a moderate reduction. The correlation between air pollutants and AQI was positive except for O3. The implications of the study are, reduction of fossil fuel powered vehicles and industrial activity can make notable positive impact on the air quality of the region.
Energy
Y. Xu; H. Jiang; K. Chen; Z. Jiang
Abstract
In this paper, a new type of wind collection device that can generate rotating wind for wind power generation has been designed to address the shortcomings of current wind power generation devices. This device can collect wind energy from different directions by changing the direction of the wind. Firstly, ...
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In this paper, a new type of wind collection device that can generate rotating wind for wind power generation has been designed to address the shortcomings of current wind power generation devices. This device can collect wind energy from different directions by changing the direction of the wind. Firstly, the simulation model for this wind collection device had been designed by the software SolidWorks. Secondly, the internal flow field of the model was modeled and simulated using Computational Fluid Dynamics, and the k-ω SST model was selected in Fluent for flow field analysis. The results showed that this device could generate an outlet wind speed of 3.8 m/s at a wind speed of 4 m/s, which verified the wind collection effect of the device. Thirdly, the outlet wind speed was taken as the optimization objective, and orthogonal optimization design was carried out on the guide convex groove in the model, and the optimal design parameters of the guide convex groove were determined. The results showed that when the width of the diversion convex groove is 47.35mm and the height is 10.65mm, the outlet wind speed is the highest, about 3.89m/s. Finally, to verify the analysis results of numerical simulation, the experimental verification of the wind collection device was carried out through physical prototypes. The results indicated that the simulation results are consistent with the physical results The design of this device can provide theoretical support for the subsequent design of a full-direction wind collection device to cope with the complex wind direction conditions.
Environment
Alireza Yousefi Kebriya; Mehdi Nadi; Ebadat Ghanbari Parmehr
Articles in Press, Accepted Manuscript, Available Online from 28 December 2023
Abstract
Mazandaran province, due to its strategic geographical location and high influx of tourists during holidays, coupled with the presence of power plants and industrial complexes, is facing pollution challenges. This research, conducted in 2022, focuses on monitoring nitrogen dioxide and ozone pollutants ...
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Mazandaran province, due to its strategic geographical location and high influx of tourists during holidays, coupled with the presence of power plants and industrial complexes, is facing pollution challenges. This research, conducted in 2022, focuses on monitoring nitrogen dioxide and ozone pollutants in the province and investigating the role of tourists during certain multi-day holidays. Utilizing Sentinel 5 satellite imagery, including daily images from holidays and non-holidays, the study compensates for the lack of regular pollution data in Mazandaran's monitoring stations by validating the satellite data against Tehran stations. Linear regression equations determine the levels of nitrogen dioxide and ozone pollutants, leading to the creation of an Air Quality Index map for Mazandaran during holidays. The results highlight a strong correlation (0.3-0.7) between satellite and ground data, with ozone pollutants exhibiting a higher correlation. The skew error is consistently zero, and the mean square error varies between 1.9-6.2 PPb for nitrogen dioxide and 1.1-5.1 PPb for ozone. Pollution estimates for different points in Mazandaran during holidays and non-holidays indicate higher ozone pollution compared to nitrogen dioxide. Ozone pollution is particularly unhealthy and very unhealthy during holiday periods, especially along the coastal areas, while non-holiday days show cleaner and healthier air quality. The pollution index map illustrates higher ozone pollution in coastal cities during holidays compared to other regions, emphasizing the impact of tourists. This research demonstrates the effectiveness of Sentinel 5 satellite in monitoring air pollution and underscores the significant influence of tourists and transportation on Mazandaran province's air quality.
Environment
Elaheh faghihnasiri; Farhad Qaderi; S. Mustapha Rahmaninezhad
Articles in Press, Accepted Manuscript, Available Online from 30 January 2024
Abstract
Industrial processes are among human activities that cause the production of a large volume of wastewater containing organic pollutants such as phenol and its derivatives. Soil remediation is crucial for enhancing environmental quality for both humans and other living organisms. This study investigated ...
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Industrial processes are among human activities that cause the production of a large volume of wastewater containing organic pollutants such as phenol and its derivatives. Soil remediation is crucial for enhancing environmental quality for both humans and other living organisms. This study investigated the use of an electro-peroxone system to remove environmental pollutants from soil. In conjunction with ozonation, the study employed electrochemically generated hydrogen peroxide using a carbon electrode, addressing concerns about transportation and storage. Experiments were structured using response surface methodology (RSM) with three variables: ozone dosages ranging from 4 to 8 l/hr, initial pollutant concentrations from 20 to 50 mg/kg, and treatment durations between 7 and 14 days. The effectiveness of phenol removal from soil was assessed by applying a consistent voltage of 2 V/cm to the soil samples in all experiments. Results revealed a negative correlation between initial pollutant concentration and ozone consumption and a positive correlation between treatment duration and pollutant removal efficiency. Optimal removal efficiency occurred with a 14-day treatment duration, an 8 l/hr ozone dosage, and a 20 mg/kg initial pollutant concentration. The electro-peroxone system's application indicates its potential as a sustainable, eco-friendly, and cost-effective approach to soil remediation for pollution.
Energy
Hamed Kamelnia; Afsaneh Ghalehnovi
Articles in Press, Accepted Manuscript, Available Online from 05 February 2024
Abstract
Electrochromic Glazing (EC) has seen a significant surge in adoption today, primarily attributed to its pivotal role in enhancing visual comfort, mitigating excessive heat, regulating cooling and heating requirements, and curbing lighting consumption, especially within office buildings. Moreover, electrochromic ...
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Electrochromic Glazing (EC) has seen a significant surge in adoption today, primarily attributed to its pivotal role in enhancing visual comfort, mitigating excessive heat, regulating cooling and heating requirements, and curbing lighting consumption, especially within office buildings. Moreover, electrochromic glazing effectively contributes to glare control. This research aims to explore the impact of electrochromic glazing, as compared to conventional clear windows, on both the south and north facades, with the overarching goal of enhancing thermal and visual comfort within an office complex located in Mashhad. The research process unfolds in two key steps. Firstly, a comprehensive building simulation was conducted to assess daylight performance and gauge thermal and visual comfort using the GrassHopper plugin. Ubsequently, the Honeybee and Ladybug plugins were harnessed to evaluate the Discomfort Glare Probability (DGP) index and the Useful Daylight Illuminance (UDI) index. The findings of this study underscore the compelling advantages of electrochromic glazing over conventional clear windows as a prime choice to maintain balanced daylight levels throughout the day.
In practice, using electrochromic glazing on both north and south facades of a building reduces the annual heating and cooling energy demand by 6.5% and 4.5%, respectively. Additionally, it has a significant impact on reducing intrusive light radiation and intolerable glare levels compared to reference transparent windows, with reductions of 40% and 34.52%, respectively.
Energy
Abbas Dehghani Rayeni; Seyyed Abdolreza Gandjalikhan Nassab
Articles in Press, Accepted Manuscript, Available Online from 09 February 2024
Abstract
In the present paper, the effect of inclination angle on the free convection airflow inside the cavity of compound parabolic collectors and also on the performance of the thermal system is examined. In analysis, the airflow equations for computations of velocity, pressure, and temperature fields and ...
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In the present paper, the effect of inclination angle on the free convection airflow inside the cavity of compound parabolic collectors and also on the performance of the thermal system is examined. In analysis, the airflow equations for computations of velocity, pressure, and temperature fields and the conduction equation for obtaining the glass cover and absorber tube temperatures are solved by the finite element technique using the COMSOL multi-physics. For this purpose, the well-known κ-ε turbulent model is employed with the Reynolds average Navier Stokes scheme. Theoretical findings reveal that the pattern of air-free convection flow and also the temperature distribution are much affected by the collector inclination angle, such that the symmetric bi-cellular air flow at zero inclined angle changes to two non-symmetric recirculated zones at a large value of the till angle. This phenomenon causes a slight increase in thermal efficiency and leads to a more uniform air temperature distribution inside the collector. Numerical findings are validated by comparison with experimental data published in the literature.
Energy
Hadi Farzan; Mohammad Hossein Shahsavari
Articles in Press, Accepted Manuscript, Available Online from 10 February 2024
Abstract
This study analyzes the thermal efficiency of a new perforated cross-flow solar air heater (SAH) integrated with encapsulated phase change material (PCM) by using an experimnetal method. Since SAHs represent low thermal efficiencies, this study introduces a novel SAH that uses two methods to address ...
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This study analyzes the thermal efficiency of a new perforated cross-flow solar air heater (SAH) integrated with encapsulated phase change material (PCM) by using an experimnetal method. Since SAHs represent low thermal efficiencies, this study introduces a novel SAH that uses two methods to address this problem: the perforated absorber with cross-flow configuration and encapsulated latent heat storage (PCM) units. The perforated cross-flow configuration improves the turbulence and, consequently, the heat exchange rate in SAHs and improves instantaneous efficiency. PCM units store thermal energy, prolong the operating period, and increase long-term efficiency. To perform thermal analysis, a perforated SAH with encapsulated PCM units was fabricated and tested outdoors at mair = of 0.012 kg/s and 0.024 kg/s in autumn while ambient and operating parameters were monitored. The experimental data reveal that the outlet temperature reaches the peak value of 38 oC and 32 oC at mair = 0.012 kg/s and 0.024 kg/s, respectively, 12 oC and 6 oC higher than the ambient temperature. During the day, the charge/discharge process occurs in the encapsulated PCM units, avoids sharp temperature gradients and flattens the outlet and absorber temperatures’ profiles. The fabricated SAH reaches the highest thermal efficiency of nearly 83.7% at mair = 0.024 kg/s, which is a suitable value compared to common SAHs.
Energy
Farhaad Nasiri Khamesloo; Davood Domiri Ganji
Articles in Press, Accepted Manuscript, Available Online from 20 March 2024
Abstract
The dissipation of heat generated in electronic and industrial chips is essential for the health of these components. For this purpose, one of the best choices is a microchannel heatsink, which offers a lower pressure drop compared to other channels while maintaining a high heat transfer rate. In this ...
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The dissipation of heat generated in electronic and industrial chips is essential for the health of these components. For this purpose, one of the best choices is a microchannel heatsink, which offers a lower pressure drop compared to other channels while maintaining a high heat transfer rate. In this study, a fractal microchannel heatsink, introduced in recent years, has been numerically investigated. To enhance the performance of the microchannel, two types of fins have been added to the microchannel walls, resulting in the creation of two new geometries. In the first new geometry, fins are placed at the bottom of the microchannel, while in the second one, fins are placed on the sidewalls of the microchannel. It is worth mentioning that the volume of fins used is consistent across both geometries. Thermal and hydraulic parameters have been examined, revealing that both new geometries increase the Nusselt number, with the highest increase observed in the microchannel with fins on the sidewalls, amounting to 28%. Additionally, both geometries increase the pumping power, with the highest increase observed in the microchannel with fins at the bottom, reaching 120%. Finally, by evaluating the performance coefficient, it was determined that the microchannel with fins on the sidewalls increases the overall performance by 3 to 6% across different flow rates, whereas the microchannel with fins at the bottom reduces the system's performance by 7%. Therefore, for efficient dissipation of the generated heat, it is preferable to use a microchannel heatsink with fins on the sidewalls.
Energy
Maryam Rafinejad; Abbas Ghayebloo
Articles in Press, Accepted Manuscript, Available Online from 20 March 2024
Abstract
In recent decades, problems such as air pollution and the reduction of fossil fuel resources led to the development of electric vehicles. Wireless power transmission is an efficient and reliable way to charge fixed and mobile electric vehicles. One of the main problems in the dynamic wireless power transmission ...
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In recent decades, problems such as air pollution and the reduction of fossil fuel resources led to the development of electric vehicles. Wireless power transmission is an efficient and reliable way to charge fixed and mobile electric vehicles. One of the main problems in the dynamic wireless power transmission method is the amount of constant power transmission and its fluctuations. The purpose of this paper is to compare six different types of winding structures for choosing the best type of winding for the transmitter side in the application of dynamic charging of electric vehicles. In this paper, the winding function method is used for more accurate modeling of coils in terms of spatial harmonics and calculation of their self and mutual inductances by changing the location of the vehicle. Also, for coil excitation, instead of using the common single-phase inverter, a three-phase type is used to reduce the power ripple. The comparison is made in the aspect of the transmission power amount and its ripple. Modeling and simulation results are presented to confirm the results
Energy
Ehsan Mehrabi Gohari; iman pishkar; ehsan omidian
Articles in Press, Accepted Manuscript, Available Online from 25 March 2024
Abstract
In this Research, the Energy and Exergy analysis of the Steam Power-plant of the ninth refinery of South Pars Complex has been studie. Fristly, according to the thermodynamic characteristics, pressure, temperature , flow rate and the type of fluid in terms of saturated water, dense liquid and super heat ...
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In this Research, the Energy and Exergy analysis of the Steam Power-plant of the ninth refinery of South Pars Complex has been studie. Fristly, according to the thermodynamic characteristics, pressure, temperature , flow rate and the type of fluid in terms of saturated water, dense liquid and super heat steam, enthalpy and entropy quantities were calculated and then using the Energy and Exergy balance relationships, the losses and efficiency of various equipments have been calculated. The results of Energy analysis showed that Boiler with 62.09 MW, Drum 107 with 17.75 MW and Deaerator with 14.17 MW have the highest energy loss and the efficiency of the first law is 41%. Also, based on the results of Exergy analysis, Boiler with 94 MW, Heat exchanger with 5.297 MW and Drum 107 with 5.233 have the highest amount of Exergy destruction and the efficiency of second law is 33%. Also, the results showed that due to the use of the steam output from the turbine in other operating units in the studied refinery, the condensers have less Exergy destruction and Energy losses compared to other power-plants. In addition, by using the solution proposed in this research to heat the input air of the combustion chamber through hot water coming out of the Continues Blow Down(CBD), it is possible to significantly increase the Exergy of the input air.
Energy
Masoomeh Bahramisamani; Mehdi Jahangiri
Articles in Press, Accepted Manuscript, Available Online from 03 April 2024
Abstract
Using wind energy for hydrogen production in Iran can be important for reasons such as abundant wind resources in Iran, reducing dependence on fossil fuels, ensuring clean energy supply, the potential for hydrogen exports, technology development and job creation. Therefore, this study signifies the first ...
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Using wind energy for hydrogen production in Iran can be important for reasons such as abundant wind resources in Iran, reducing dependence on fossil fuels, ensuring clean energy supply, the potential for hydrogen exports, technology development and job creation. Therefore, this study signifies the first exploration into the potential for generating electricity and producing hydrogen in ten wind-rich cities in Iran. HOMER V.2.81 software was used for simulations, and the wind data used are averaged over a 25-year period. The results show that in Iran, the price range for wind power is $0.515-$0.620 per kWh in the top 10 stations. Bandar Abbas, Parsabad, and Khalkhal had the best economic and environmental performance, respectively. The highest percentage of renewable electricity production is 71% in Bandar Abbas. Finally, the amount of hydrogen produced based on four common electrolyzer types in Iran was investigated. The total annual hydrogen production per ton for SOE, MCE, AE, and PEME electrolysis method at the examined stations is 131.29, 93.43, 40.99, and 30.69, respectively. According to the results, the highest hydrogen production with a value of 16.87 tons per year is related to the Bandar Abbas station and the SOE electrolysis method. The lowest hydrogen production, with a value of 2.36 tons per year, is related to the Alvand station and the PEME electrolysis method.
Environment
hassan Farsi; Mehrdad Rohani; Sajad Mohamadzadeh
Articles in Press, Accepted Manuscript, Available Online from 08 April 2024
Abstract
Facial feature recognition (FFR) has witnessed a remarkable surge in recent years, driven by its extensive applications in identity recognition, security, and intelligent imaging. The UTKFace dataset plays a pivotal role in advancing FFR by providing a rich dataset of facial images with accurate age, ...
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Facial feature recognition (FFR) has witnessed a remarkable surge in recent years, driven by its extensive applications in identity recognition, security, and intelligent imaging. The UTKFace dataset plays a pivotal role in advancing FFR by providing a rich dataset of facial images with accurate age, gender, and race labels. This paper proposes a novel multi-task learning (MTL) model that leverages the powerful Efficient-Net architecture and incorporates attention-based learning with two key innovations. First, we introduce an age-specific loss function that minimizes the impact of errors in less critical cases while focusing the learning process on accurate age estimation within sensitive age ranges. This innovation is trained using the UTKFace dataset and is specifically optimized to improve accuracy in age estimation across different age groups. Second, we present an enhanced attention mechanism that guides the model to prioritize features that contribute to more robust FFR. This mechanism is trained on the diverse and challenging images of UTKFace and is capable of identifying subtle and discriminative features in faces for more accurate gender, race, and age recognition. Furthermore, our proposed method achieves a 30% reduction in model parameters compared to the baseline network while maintaining accuracy. Extensive comparisons with existing state-of-the-art methods demonstrate the efficiency and effectiveness of our proposed approach. Using the UTKFace dataset as the evaluation benchmark, our model achieves a 0.62% improvement in gender recognition accuracy, a 2.35% improvement in race recognition accuracy, and a noteworthy 3.23-year reduction in mean absolute error for age estimation.
Energy
Neda Daei parizi; Mansour Nikpour; Hossein Fallah
Articles in Press, Accepted Manuscript, Available Online from 17 April 2024
Abstract
For reading and writing in classrooms therefore a lot of energy is consumed in educational spaces. Limitation of fossil fuels and environmental pollution are two subjects that demonstrate the importance and significance of the present study. Previous studies show that window size and configuration have ...
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For reading and writing in classrooms therefore a lot of energy is consumed in educational spaces. Limitation of fossil fuels and environmental pollution are two subjects that demonstrate the importance and significance of the present study. Previous studies show that window size and configuration have a significant effect on daylight quality but numbers and the ways of expansion of windows in horizontal and vertical directions of the wall have not been investigated in classrooms in hot and arid regions of Kerman city. The objective of this paper is to evaluate the daylight indicators in different classrooms when different numbers of windows (from 1 window to 5 windows) are applied both horizontal and vertical expansion in each window area from (10%c WWR to 60% WWR). This research has been done through the simulation of different classrooms in Design Builder software under Kerman weather data. Validation of Design Builder has been evaluated through experimental measurement of two actual classrooms and comparing the simulation results and experimental data. The findings of this research demonstrated that using a greater number of windows in classrooms causes a decrease in the amount of daylight penetrating the classrooms.
