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.
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.
Energy
iman pishkar; Ehsan Mehrabi Gohari
Articles in Press, Accepted Manuscript, Available Online from 22 April 2024
Abstract
The present work is the first study of its kind aimed at minimizing the energy consumption of the RO system pump and then finding the optimal configuration of a microgrid based on renewable energy in off-grid and on-grid modes. Comparing with traditional methods of using the power grid and diesel generators ...
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The present work is the first study of its kind aimed at minimizing the energy consumption of the RO system pump and then finding the optimal configuration of a microgrid based on renewable energy in off-grid and on-grid modes. Comparing with traditional methods of using the power grid and diesel generators to supply the required power for the RO system prompts decision-makers and investors in this field to better advance the industry based on the energy-economic-environmental analyses of this work. In this research, the initial phase involved an examination using WAVE V.1.82q software to assess the viability of purifying surface water to provide a daily water supply of 3220 m3, employing BW30-400 modules. Subsequently, efforts were made to minimize operational pressure and thus lower the operational costs of the system through the utilization of low-energy modules like XLE-440i. Lastly, the evaluation of the power supply for the RO pump system was carried out across six different scenarios using HOMER V.2.81 software. The simulation results indicated that in the most favorable scenario, the energy required per m3 of water treatment stands at approximately 0.53 kWh. When a diesel generator serves as a backup, the lowest electricity production cost is associated with the solar system at $0.355 per kWh, with solar energy contributing to 91% of electricity generation. On the other hand, when grid electricity is the backup source, the lowest electricity production cost amounts to $0.024 per kWh, with only 1% of electricity generated from solar energy.
Energy
A. Bagheri; S. Karimian Aliabadi; F. Ommi; K. Ghaemi Osgouie
Abstract
Herein, a non-boiling two-phase flow containing air and water through a downward flow in a vertical tube with helical corrugations has been investigated. In this simulation, various flow rates for air and water are considered, and three corrugation pitches 1, 1.5, and 2 cm are included. It can be seen ...
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Herein, a non-boiling two-phase flow containing air and water through a downward flow in a vertical tube with helical corrugations has been investigated. In this simulation, various flow rates for air and water are considered, and three corrugation pitches 1, 1.5, and 2 cm are included. It can be seen in the results that the pressure drop values decrease with an increase in volume fraction. It should be noted that the reduction of pressure drop values with the reduction of volume fraction (VF) is based on the reduction of the water flow rate, which is visible. By comparing the pressure drop values for each corrugation pitch, it can be seen that as the pitch decreases, the pressure drop values increase significantly. The results for Nusselt number show that Nusselt number decreased with an increase in the volume fraction. 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. Ultimately, the cost-benefit ratio has been utilized to show real results for each studied case.
Energy
H. Radaei; R. Shafaghat; S. Talesh Amiri; B. Alizadeh Kharkeshi
Abstract
Considering that the heat required for the Waste heat recovery (WHR) cycle of the engine is provided from two parts of the exhaust gas and the cooling system, the mutual influence of the WHR cycle on the engine performance is undeniable. Therefore, in this numerical study, an attempt has been made to ...
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Considering that the heat required for the Waste heat recovery (WHR) cycle of the engine is provided from two parts of the exhaust gas and the cooling system, the mutual influence of the WHR cycle on the engine performance is undeniable. Therefore, in this numerical study, an attempt has been made to thermodynamically evaluate the effect of the implementation of the WHR cycle on the engine efficiency. For this purpose, the 16 cylinder MTU 4000 R43L heavy diesel engine was simulated and a comparison was made between numerical and experimental results. Finally, the SRC heat recovery cycle was designed and applied in the simulated model according to the desired limits and the temperature range of the engine operation. At low speed with the application of the WHR cycle, the output net power did not drop much, but at the maximum speed and power, a power loss of about 4% is observed. At 1130 rpm, the power did not increase much. At 1600 rpm, the power increase is reduced to about 2.3%. At 1800 rpm, due to the significant increase in exhaust gas temperature, the total power value increased by about 4%.
Energy
F. Yazdandoost; S. A. Yazdani
Abstract
Insisting on independently providing energy due to fossil fuel availability and Economic-political purposes has imposed financial-environmental risks on countries. Inefficient obsolete infrastructures and technologies have caused devastating losses causing technical vulnerabilities in the energy sector. ...
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Insisting on independently providing energy due to fossil fuel availability and Economic-political purposes has imposed financial-environmental risks on countries. Inefficient obsolete infrastructures and technologies have caused devastating losses causing technical vulnerabilities in the energy sector. Ungainful increasing consumption of water resources has superimposed severe environmental degradation, threatening long-term energy planning. Successively, the energy security debate has turned into a challenging necessity for countries. This study developed a classic approach based on Modern Portfolio Theory (MPT) and Capital Allocation Line (CAL) reinforced with aggregated evaluative measures to deal with the financial-environmental complexities of national energy portfolios. Results prove that countries are not even aware of the risky hidden brittleness of their energy portfolio. Futuristic policymaking should be adapted to gradually change the national energy structure from fossil fuel dependency to portfolio thinking to avoid risks and achieve more security.
Energy
N. Amani; A. Sabamehr
Abstract
The purpose of this research is to analyze the energy of a residential building in the city of Tabriz with a cold and dry climate using energy simulation to provide a model to minimize energy consumption. A comparative model of energy consumption analysis in a three-story building unit with dimensions ...
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The purpose of this research is to analyze the energy of a residential building in the city of Tabriz with a cold and dry climate using energy simulation to provide a model to minimize energy consumption. A comparative model of energy consumption analysis in a three-story building unit with dimensions of 181 square meters is presented using 5 layout modes in the wall, floor, ceiling, window and door. The number of 5 designs with different arrangement of rooms and different number of windows were compared in terms of energy conservation in 51 different diagrams and the optimal energy saving design is selected. In the next step, according to the obtained results, the design of the building in the desired site is discussed. At the end, in order to check the amount of energy absorbed in the building, energy diagrams will be obtained for the thermal region of the coldest day of the year. The results show that the most optimal energy consumption of the residential building is related to the design of plan B with the fabric gains value of 41767 Wh. After that, the designed plan A show the most optimal energy consumption in the building with fabric gains value of 41028 Wh in the month of July. The results of this research are useful for energy efficiency of residential buildings and environmental management in future.
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.
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.
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.
Energy
B. Alizadeh Kharkeshi; R. Shafaghat; S. Talesh Amiri; A. M. Tahan; A. Ardebilipour
Abstract
In waste heat recovery from a heavy-duty diesel engine, with a focus on engine speed's impact, is explored. The critical problem of enhancing energy efficiency and reducing emissions through waste heat utilization is addressed. Waste heat in internal combustion engines, vital for sustainable energy use ...
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In waste heat recovery from a heavy-duty diesel engine, with a focus on engine speed's impact, is explored. The critical problem of enhancing energy efficiency and reducing emissions through waste heat utilization is addressed. Waste heat in internal combustion engines, vital for sustainable energy use and environmental preservation, is investigated. Experimental analysis and thermodynamic modeling introduce Organic Rankine Cycle (ORC), Steam Rankine Cycle (SRC), and Combined Steam and Organic Rankine Cycle (CSO) for waste heat recovery. A non-linear relationship between engine speed and waste heat is identified. Waste heat increases up to 1600 rpm and decreases thereafter. The CSO cycle outperforms ORC and SRC cycles, achieving 43.4% higher efficiency. Fuel energy savings demonstrate CSO's superior economy, along with excellence in Annual Carbon Dioxide Emissions Reduction (ACO2ER). Waste heat recovery knowledge is advanced by introducing the efficient CSO cycle, contributing significantly to existing research.
Energy
N. Mirrashid; S. M. Rakhtala
Abstract
In this paper, a feasibility study is conducted on a photovoltaic-low-speed wind turbine-battery zero-energy building for a 175 m2 residential house in Gorgan. First, the climatological data of Gorgan City related to the amount of solar radiation and wind speed for the past 50 years have been extracted ...
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In this paper, a feasibility study is conducted on a photovoltaic-low-speed wind turbine-battery zero-energy building for a 175 m2 residential house in Gorgan. First, the climatological data of Gorgan City related to the amount of solar radiation and wind speed for the past 50 years have been extracted and then they are analyzed annually, monthly, and hourly using Climate Consultant software to check how Renewable resources can be used to produce clean energy. To determine the number of devices required, the annual energy requirement of the residential unit should be estimated. For this purpose, the power and energy consumption of the residential unit has been estimated based on its consumption data in the last year and analyzed using RETScreen1 software. The designed zero energy system has energy exchange with the grid and sends excess energy to it. The results of climate data analysis show that there is a possibility of wind and solar energy efficiency in this region. Although the price of energy in the region is low, due to economic efficiency, the lack of non-renewable energy resources, and the need to replace these resources, the use of wind turbines and solar panels to supply the required electrical energy is necessary.
Energy
A. Jabbari; M. Basaki; M. R. Sheykholeslami
Abstract
In this paper, an axial flux permanent magnet generator for a 30 kW direct drive wind turbine is designed and the design parameters were optimized with the aim of achieving high efficiency. In order to reduce the cogging torque and electromagnetic torque ripple components, the air core topology has been ...
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In this paper, an axial flux permanent magnet generator for a 30 kW direct drive wind turbine is designed and the design parameters were optimized with the aim of achieving high efficiency. In order to reduce the cogging torque and electromagnetic torque ripple components, the air core topology has been used, and with the aim of increasing the power capacity of the generator, a modular structure has been used. The advantage of the modular design is that each module can be considered as a generator unit and depending on the wind speed conditions, the number of units corresponding to the wind speed can be placed in the circuit and the generator will always work with maximum efficiency. First, by using the governing equations, the dimensions and performance characteristics of the generator are determined, and then a generator prototype is fabricated based on the electromagnetic design. In order to evaluate the output performance of the generator, machine simulation was performed in Maxwell finite element analysis software and the characteristic curves of voltage, current and ohmic losses were extracted. In order to evaluate the accuracy of the results, the outcomes of the analytical method have been compared with the experimental tests results.
Energy
F. Hasanlu; A. Fallah-Sabet; A. Fereidunian
Abstract
The electric energy demand has been increasing, following digitalization and development of urbanization, which has led to functional enhancement of home energy management system (HEMS) and its subsystems. A great amount of the produced electricity is used for household loads, whereas self-sufficient ...
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The electric energy demand has been increasing, following digitalization and development of urbanization, which has led to functional enhancement of home energy management system (HEMS) and its subsystems. A great amount of the produced electricity is used for household loads, whereas self-sufficient smart homes can supply all or a large portion of their electricity consumption by using renewable energy resources. In this study, an MILP model is formulated for energy scheduling on a 24-hour time horizon, to achieve the optimal performance of each home appliance for minimizing the smart home energy bill. The studied smart home can exchange electrical energy with the upstream network. A sensitivity analysis has been performed to show the impact of the changes in scheduling and energy prices on the electricity energy bill. The impact of the presence of renewable resources and electrical storage is studied on the electricity energy bill and the electrical energy sales profit of the house in different scenarios. Numerical results show that using the proposed model in the self-sufficient smart home reduces the amount of power purchased from the grid by 45%, transfers energy to the grid at some hours, and the energy bill is reduced by 65%.
Energy
P. Hedayati; A. Ramiar; N. Hedayati
Abstract
Wind energy is a prominent renewable energy source, and Vertical Axis Wind Turbines (VAWTs) offer distinct advantages, including adaptability to changing wind directions and reduced noise levels. This paper conducts a numerical investigation into the impact of flat and curved stator blades on VAWTs, ...
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Wind energy is a prominent renewable energy source, and Vertical Axis Wind Turbines (VAWTs) offer distinct advantages, including adaptability to changing wind directions and reduced noise levels. This paper conducts a numerical investigation into the impact of flat and curved stator blades on VAWTs, specifically the Savonius turbine, under 2D, viscous, turbulent, and steady flow conditions. Four stator blade configurations were examined, including no stator blades, smooth stator blades, twisted stator blades (Case A), and both blades being concave (Case B). The study reveals that curved stator blades enhance VAWT performance, with Case B exhibiting the most efficient performance. The results show pressure distribution on the turbine blades is non-uniform, with high and low-pressure zones, predominantly on the windward side. The presence of stator blades enhances pressure on all turbine blades, with Case B exhibiting the most optimal pressure distribution. Detailed observation of streamline and velocity distribution reveals improved flow lines for Case B, leading to more effective turbine blade performance. Case B consistently produces the highest turbine torque, with a maximum value of approximately 2.1 N·m achieved at Re = 15750. The torque demonstrates a positive correlation with increasing Reynolds numbers. The study further introduces a non-dimensional torque ratio analysis, where Case B attains 7.59 times higher torque than the reference case at Reynolds number 15750. The sensitivity of torque increase with respect to Reynolds number change highlights that Case B (with a slope of torque increase at around 4.5e-04) is the most responsive within the studied Reynolds number range.
Energy
M. Movehhedi Nia; M. Nikpour; E. Jahanshahi Javaran
Abstract
The research aims to develop sustainable daylighting strategies for contemporary buildings by drawing inspiration from traditional vernacular housing solutions. In this study, the daylight factors of a contemporary residential space with a central courtyard which is located in Kerman, Iran is evaluated. ...
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The research aims to develop sustainable daylighting strategies for contemporary buildings by drawing inspiration from traditional vernacular housing solutions. In this study, the daylight factors of a contemporary residential space with a central courtyard which is located in Kerman, Iran is evaluated. After modeling the building in Design Builder software, the U-values of the external walls, roof, floor and windows based on the available materials in the market of Iran are calculated. The results of daylight simulations are presented in term of Average DF (%), Work plane Illuminanace (Lux) and Uniformity Ratio as well as annual Indicators of daylight such as sDA and UDI. Zone 3 in the ground floor which is a space under top lit atrium acts as a source of daylight. Although, Zone 5 in the ground floor has reasonable daylight factor, the uniformity ratio is not acceptable due to simultaneously existing the areas of little and high illuminance. Zone 7 in the first floor as a public sapce can provide large potential for daylight utilization with DF equal to 2.6% and average WPI with 826 Lux because there is a possibility to receive daylight from east direction with designing central courtyard in the first floor plan.
Energy
S. N. Mosavian; H. Eskandari
Abstract
This research, conducted in Gotvand, southwest Iran, evaluated the energy balance of a field system which watermelon produced in it. In the current research, energy inputs of watermelon planting were measured. To reach this goal, questionnaires were given to the farmers to record the amount of energy ...
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This research, conducted in Gotvand, southwest Iran, evaluated the energy balance of a field system which watermelon produced in it. In the current research, energy inputs of watermelon planting were measured. To reach this goal, questionnaires were given to the farmers to record the amount of energy input to their watermelon planting field. Statistical analysis of the data revealed that nitrogen was the input with the highest consumption of energy (4175 MJ.ha-1) followed by diesel fuel. About 90% of the consumed energy of watermelon planting system was seen for energies which cannot be renewed. The results showed that the efficiency of energy consumption was positive, indicating that the amount of output energy was higher than that of input energy. With each unit of energy was consumed, 4.86 units of energy were produced, which indicates high energy efficiency. For improving the efficiency of energy usage in the watermelon planting system, nitrogen application to the system should be reduced and it can be reached by suitable rotation which diminish the nitrogen needs.
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 ...
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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.
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 ...
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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.
