Review Paper
Energy Policy
M. Monfared; E. Hasani Alavy; M. Khanpoor Siahdarka; F. Rahnama
Abstract
In order to systematically reduce the risk of SARS-CoV-2 infection in indoor space, it’s important to understand the building design strategies and air quality enhancement methods that set to mitigate this threat. This paper aims to introduce the different HVAC technologies used to mitigate the ...
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In order to systematically reduce the risk of SARS-CoV-2 infection in indoor space, it’s important to understand the building design strategies and air quality enhancement methods that set to mitigate this threat. This paper aims to introduce the different HVAC technologies used to mitigate the spread of COVID-19 in university settings in particular. Many of these technologies came to be as an outcome of scientific interest in the enhancement of indoor environmental quality. Thus, it is important to understand where airborne pathogens fit in the overall scheme of Indoor Air Health. Similarly, this paper set to reimagine architectural methods as solutions to the problem of airborne transmission of diseases. Based on the urgency of the problem and the demand of the market this paper discusses a summary of applicable technologies and strategies to combat airborne viruses, particularly COVID-19, in ventilation systems and enclosed spaces. By presenting an overview of the problem and the solutions that integrate engineering controls, design strategies and, indoor air sanitization techniques aim to create healthier indoor environments this paper aspires to move the research forward.
Review Paper
Energy Policy
M. Shiri Dezaki; Z. Zandian Sefiddashti; M. Jahangiri; A. Haghani; A. Tahmasebi
Abstract
The outbreak of Coronavirus disease (COVID-19) in late 2019 and its eventual transformation into a global pandemic caused a shock wave across countries. The renewable energy (RE) sector, which has always been one of the leading areas for promoting environmental sustainability, has not been spared from ...
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The outbreak of Coronavirus disease (COVID-19) in late 2019 and its eventual transformation into a global pandemic caused a shock wave across countries. The renewable energy (RE) sector, which has always been one of the leading areas for promoting environmental sustainability, has not been spared from the epidemic. The integration of the effects of the epidemic on the global economy and the fluctuation of oil prices due to global quarantines around the world increased the impact of this disease on the RE industry. Although the COVID-19 crisis has had a negative effect on efforts to develop RE, analysts believe that in the future, more of the world's energy needs will come from RE sources. The International Energy Agency (IEA) has claimed that RE consumption is likely to increase because people tend to have clean and sustainable energy sources such as wind, water, and solar energy more than before. In the present work, the effects of the COVID-19 outbreak on environmental changes, energy consumption, the need to use RE, investments made in the field of RE, and the well-being of the people of the world are examined and details and results will be discussed. The main aim of the present work is to review the studies of researchers on the impact of COVID-19 disease on the environment and RE.
Original Article
Transformation of Generated Electricity by Renewable Energies to Grid
M. Mahmoudian; S. Sadi; J. Gholami; Alirza Karimi
Abstract
This paper is dealt with energy hub systems in order to evaluate the sensitivity analysis of output power carriers in terms of input electricity and natural gas. Unlike the recent works which were solitary concentrated at operational cost minimization, in this research not only the energy carriers of ...
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This paper is dealt with energy hub systems in order to evaluate the sensitivity analysis of output power carriers in terms of input electricity and natural gas. Unlike the recent works which were solitary concentrated at operational cost minimization, in this research not only the energy carriers of proposed hub are being modeled, but also the sensitivity analysis of each power supplier are investigated. Since some of input power carriers in the hub, are decreased slightly or immediately according to unsolicited situations, the output electrical or thermal profile may not be supplied completely. Therefore the network operator must make a proper decision to utilize the best carriers not to reduce the system efficiency if possible. In this regard, the objective function including the energy costs for electrical, thermal and cooling demand carriers is optimized and the best solution will be extracted based on conditional value at risk (CAVR) of electricity market actors, using GAMS/CPLEX software, results in the higher the risk the network operator takes, the higher the profit from futures contracts. In the next step, the electricity price is predicted using ARIMA approach for the next four weeks and the sensitivity analysis for the future of the energy hub will be examined. The simulation results and changes in the share of energy carriers show that the importance of passive defense must be considered in the planning for energy supply of office buildings and the percentage of unsupplied energy must be studied.
Original Article
Fuel Cells
M. Rostami; A.H. Farajollahi; M. Marefati; R. Fili; F. Bagherpor
Abstract
The propulsion system of an Unmanned Aerial Vehicle (UAV) plays an essential role in its performance, stability and flight endurance. In this study, two types of propulsion systems for UAV (differentiated based on fuel type) are studied to determine their characteristics and advantages. These proposed ...
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The propulsion system of an Unmanned Aerial Vehicle (UAV) plays an essential role in its performance, stability and flight endurance. In this study, two types of propulsion systems for UAV (differentiated based on fuel type) are studied to determine their characteristics and advantages. These proposed propulsion systems are using a solid oxide fuel cell (SOFC) to generate the heat required for the operation of the turbine and generating thrust. To achieve the best operating condition, a multi-objective Non-Dominated Sorting Genetic Algorithm (NSGA-II) in MATLAB is used to decide key design parameters. For reaching the best conditions where the acceptable thrust is accompanied by reasonable flight duration, the TOPSIS decision-making method was considered. Results indicated that the efficiency and generated power of the propulsion system will increase by higher flight altitude or compressor pressure ratio. Also, due to the recirculation of fuel in the SOFC’s anode, the higher efficiency is observed in comparison when hydrogen is used; since anode-recirculation causes higher fuel utilization. The optimization result shows that the efficiency and fuel consumption for the hydrogen-fueled system is 48.7% and 0.0024g/s, respectively, and 67.9% and 0.0066kg/s for methane-fueled engine. It was also found that, maximum efficiency for both hydrogen- and methane-fueled systems are available with the stack temperature of 1025 K; however maximum thrust for these systems is at the stack temperature of 1075 K. In addition, increasing fuel rate of the SOFC power unit helps the process of generating extra power and thrust for UAVs.
Original Article
Fuel Cells
M. Rostami; A. H. Farajollahi; F. Bagherpor; V. Sfandiyar
Abstract
Polymer electrolyte membrane fuel cells (PEMFCs) produce high power density efficiently and in a pollution-free way. Therefore, it is employed in UAVs. Flow fields play key role in the performance of PEMFC-powered UAVs. In this study, a novel flow field named modified combined was introduced and investigated ...
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Polymer electrolyte membrane fuel cells (PEMFCs) produce high power density efficiently and in a pollution-free way. Therefore, it is employed in UAVs. Flow fields play key role in the performance of PEMFC-powered UAVs. In this study, a novel flow field named modified combined was introduced and investigated by a three-dimensional and two-phase PEMFC model. In the flow field main channels are tapered aiming to reinforce the performance. The study consists of two steps. In the first stage, modified combined was compared with parallel, serpentine, interdigitated, and combined. The results showed that in the modified combined compared with simple combined, pressure drop decreased 22.6%. Modified combined demonstrated suitable oxygen distribution and appropriate management and the specific power of modified combined is the highest value among all flow fields. Finally, the effect of atmospheric conditions on the performance of the PEMFC with modified combined flow field was studied and two equations were presented to predict the performance at 0.4V and 0.7V at the different altitudes of flight. The findings unveiled the point that in the cruise phase of the flight, low voltage is more suitable for PEMFC-driven UAV with modified combined flow field. All in all, modified combined flow field and low voltage are recommended to be utilized in PEMFCs as propulsion system of UAVs.
Original Article
Electricity Generation by Green Energy Sources
H. Ashofteh; A. Behzadi Forough
Abstract
Energy is one of the most critical factors in economic development, but achieving sustainable development is impossible without environmental protection and improving economic conditions. If a country is dependent on energy, any structural reform policies to reduce energy consumption may reduce economic ...
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Energy is one of the most critical factors in economic development, but achieving sustainable development is impossible without environmental protection and improving economic conditions. If a country is dependent on energy, any structural reform policies to reduce energy consumption may reduce economic growth. Saving energy consumption and the development and application of alternative technologies, especially renewable energy, has a significant role in controlling and reducing the consumption of fossil energy carriers and, consequently, reducing the emission of environmental pollutants and achieving sustainable development. This article deals with the feasibility of constructing renewable energy power plants in Khoy city. First, using RETSCREEN software, the economic and environmental conditions of the construction of renewable energy power plants in Khoy city are examined. Using PVSYST software, the requirements for constructing solar power plants are discussed in a specialized way. In this article, the inflation rate is 12%, and the interest rate is 4%. The construction of solar and geothermal power plants in this city can be prioritized based on the results. The solar power plant has a production capacity of 30 MW. 212194 meters of land, and a capital of 40 million dollars are needed to construct this solar power plant. The payback period of this project in Khoy city is estimated at 25 years.
Original Article
Low-carbon Technologies
F. Shateri Aliabad; Y. Ebazadeh; R. Alayi; I. Suwarno; A. Najafi; S. Ollah Mohammadi-Aylar
Abstract
In this research, technical and economic analysis of the use of storage devices in the hybrid system of wind and solar is performed with the aim of providing a maximum electrical load of residential buildings. To this aim, two scenarios of grid-connected and off-grid system have been studied. two parameters ...
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In this research, technical and economic analysis of the use of storage devices in the hybrid system of wind and solar is performed with the aim of providing a maximum electrical load of residential buildings. To this aim, two scenarios of grid-connected and off-grid system have been studied. two parameters of high reliability and cost per production capacity were used. According to these two parameters, due to the low cost of grid energy and the high cost of purchasing the second scenario cell was selected with the grid-connected system approach. Based on this system, the final generation that has a surplus of production sells the energy to the network and uses the network to supply the load when there is a lack of power to supply the load. According to the cases mentioned in the second scenario, more than 50% of the requested load is supplied by the photovoltaic cell, which indicates the high potential of the study area. For the selected system, the return on investment was 7.53 years, considering the cost of energy is 0.13 $/kWh
Original Article
Photovoltaic Systems
Hossein Eshghi; Mostafa Kahani; mohammad Zamen
Abstract
The cooling process of photovoltaic (PV) panel is one the main issue in in the field of solar systems. The temperature of solar cells increases when solar radiation and also ambient temperature increase. Increasing the cell temperature reduces the electrical output power of the panels as well as their ...
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The cooling process of photovoltaic (PV) panel is one the main issue in in the field of solar systems. The temperature of solar cells increases when solar radiation and also ambient temperature increase. Increasing the cell temperature reduces the electrical output power of the panels as well as their lifetime. To solve this problem, various methods have been provided for cooling the panels. One of these methods is the application of heat pipes. In this research, a PV panel equipped with thermosyphon heat pipe is introduced. The thermosyphon was connected to the back sheet of the panel to enhance the cooling effect of the PV system. Instead of using polyvinyl fluoride polymer, unlike conventional panels, an aluminum plate was used to connect the heat pipe to the back of the panel to have better cooling. In addition, to increase the heat transfer area between heat pipe and back surface of the panel, a special groove was drilled on the aluminum plate. Three different filling ratios (25, 45 and 65%) of distilled water as the working fluid were used in thermosyphon. The best performance of the systems was obtained at 45% of filling ratio, in which, the electrical power of the PV panel equipped with heat pipe was around 3.2% better than the conventional PV panel. In this case, 6.8 °C temperature difference was observed in the water tank connected to the condenser section of heat pipe which means that 54 kJ heat was transferred to the water in the tank.
Original Article
Transformation of Generated Electricity by Renewable Energies to Grid
Amir Ghaedi; Mehrdad Mahmoudian; Reza Sedaghati
Abstract
The widespread growing of electric vehicles (EVs) in distribution networks could be a variety of challenges and opportunities for the electricity network. This issue is important because the owners of electric vehicles are trying to maximize their profits, which in turn can cause many problems such as ...
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The widespread growing of electric vehicles (EVs) in distribution networks could be a variety of challenges and opportunities for the electricity network. This issue is important because the owners of electric vehicles are trying to maximize their profits, which in turn can cause many problems such as increased losses, congestion, increase network costs, etc. in distribution networks. Therefore, it is required to study different aspects of this new technology such as reliability and failure rate. For this purpose, the presented paper introduces a reliability model based on the Markov theory for different types of electric vehicles, and the main novelty is to determine the impact of the failure rate of the composed components of the each electric vehicle on the overall failure of the vehicle. In the proposed reliability models for these electric vehicles, the failure of the main composed components is considered. To compare different types of electric vehicles from reliability point of view, numerical results associated with the reliability evaluation of these vehicles are given. It is deduced from the numerical results associated to the reliability evaluation of different types of electric vehicles that the reliability of the compound plug-in hybrid electric vehicle is more than the other technologies.
Original Article
Biomass Energy Sources
Gemechu Jebeso Morketo; Miftah Fekadu; Tatek Dajenie
Abstract
The present study investigated appropriate tree species for biomass energy utilization by determining trees' dry biomass and fuel value index, taking into account that developing countries rely heavily on fuelwood for energy consumption. In Ethiopia, biomass currently meets more than 89.5% of total ...
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The present study investigated appropriate tree species for biomass energy utilization by determining trees' dry biomass and fuel value index, taking into account that developing countries rely heavily on fuelwood for energy consumption. In Ethiopia, biomass currently meets more than 89.5% of total energy consumption. Despite this reliance on biomass, there is a scarcity of fuelwood as well as data on dry biomass potential and fuel value indices of tree species utilized in various parts of the country. This study was done on the selection of trees for fuelwood purposes based on their dry biomass potential and fuel quality characteristics. Five highly performed Eucalyptus tree species were selected and aboveground biomass was measured using the destructive approach, whereas the fuel value index was computed using the effective method with four parameters (Calorific Value, Wood density, Ash content and Moisture content). These parameters were determined following the American Society for Testing and Materials method. Finally, aboveground biomass and carbon content varied from 13.96kg to 87.47kg and 6.03kg to 37.86 kg Tree-1, respectively. The biomass and carbon content of E. globulus and E. viminalis were both high. The maximum fuel value index was 276.34 for E. saligna. The computed fuel characteristics were statistically varied among tree species at (P ≤0.0001). Based on the tree fuel characteristics findings, E. globulus, E. viminalis, and E. saligna were identified as the best fuelwood species and were suggested for future plantations.
Original Article
Systems with Low Energy Consumption
Seyed E. Hoseini; M. Simab; B. Bahmani
Abstract
The argument of power systems planning in home microgrids has become one of the burning topics in optimization studies today among the researchers. Since the installation and use of high-capacity energy sources in power systems have many limitations and constraints, so part of the perspective of power ...
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The argument of power systems planning in home microgrids has become one of the burning topics in optimization studies today among the researchers. Since the installation and use of high-capacity energy sources in power systems have many limitations and constraints, so part of the perspective of power systems studies tends to operate residential microgrids. For this purpose, in this paper, operation planning is based on a residential microgrid consisting of combined heat and power (CHP), heat storage tank and boiler, and when possible, surplus electricity is sold to the upstream network to generate revenue. One of the innovations of this paper is the use of the exergy function to complete the optimization and, in practice, combine energy with economics. Other objective functions of this paper are to discuss the reduction of carbon dioxide in the air and the cost of operation. Energy management and planning in this home microgrid is tested with different capacities and types of CHPs, so that the home operator can choose the best mode to use. The multi-stage decision based dynamic programing (MSD-DP) optimization approach is used to minimize the operation costs of proposed framework. The most important innovation of this paper is the use of exergy function for energy management in a residential complex where CHP can also be used to generate electricity and heat simultaneously. Therefore, determining the capacity of CHP and the possibility of exchanging electricity with the upstream network can be mentioned as other innovations of this research.
Original Article
Photovoltaic Systems
M. Mirzaei Omrani; M. Mirzaei Omrani
Abstract
Solar energy as renewable and clean energy has a remarkable share in improving the water-energy-food nexus. However, due to occupying a vast area of land, the development of large-scale photovoltaic systems is a serious challenge, particularly in regions with land restrictions. As a solution, it is argued ...
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Solar energy as renewable and clean energy has a remarkable share in improving the water-energy-food nexus. However, due to occupying a vast area of land, the development of large-scale photovoltaic systems is a serious challenge, particularly in regions with land restrictions. As a solution, it is argued that the installation of the floating photovoltaic systems on the water reservoirs can save land as well as reduce the evaporation rate. The aim of this study is to economically and environmentally evaluate the feasibility of the installation of a 10-megawatt floating photovoltaic power plant on a water reservoir. Results show that the payback period of investment and internal rate of return are achieved at 5.2 years and 20.4%, respectively. It is also found that if only 0.3% of the water reservoir surface is covered, evaporation volume will be decreased from 441.2 up to 515.2 thousand cubic meters. Moreover, environmental assessment demonstrates that 8470 to 15311 tons of CO2 and 27 to 52.3 tons of NOx are not released into the atmosphere. Ultimately, sensitivity analysis proves that if the capital cost is reduced by 30%, the payback period will be shortened to 3.6 years. Furthermore, such a project in Chah-nimeh will be profitable as long as the electricity purchasing tariffs are more than US$ 0.096/kWh.
Original Article
M. G. Ghebrezgabher; A. K. Weldegabir
Abstract
The request to improve electric supply in Eritrea has motivated the country to look for alternative energy resources to enhance existing power. Eritrea, being in tropics, is well situated to harvest solar energy to improve its power supply status. Although several solar energy projects have been initiated, ...
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The request to improve electric supply in Eritrea has motivated the country to look for alternative energy resources to enhance existing power. Eritrea, being in tropics, is well situated to harvest solar energy to improve its power supply status. Although several solar energy projects have been initiated, very small has been done in the country. Therefore, this research paper aims to evaluate and investigate the regional solar energy potential (SEP) in Eritrea using remote sensing data and ArcGIS applications. The digital elevation model (DEM) data was adopted to estimate the SEP and suitability of energy in the country. In addition, areal solar radiation method is applied in ArcGIS 9.3 to extract the SEP and to evaluate suitability of this energy for the development of photovoltaics (PVs) power. The results revealed that approximately 69.03%, and 30.96% of the country was excellent and highly suitable to harness SEP, respectively, and only about 0.004% was considered as unsuitable. Therefore, this research may be useful as reference for future study and to motivate the country to improve its power supply using this alternative energy.
Original Article
Energy Policy
M. Ansari Manesh; E. Sarkardehee; S. Jafarian
Abstract
Human beings spend most of their time in indoor environments. A large part of people around the world work and live in urban areas. Economic productivity is an important goal of different buildings, especially office buildings. Various factors play a role in economic productivity, including reducing ...
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Human beings spend most of their time in indoor environments. A large part of people around the world work and live in urban areas. Economic productivity is an important goal of different buildings, especially office buildings. Various factors play a role in economic productivity, including reducing energy consumption, managerial programs, and increasing the personnel’s efficacy. Increasing attention to efficiency see day by day. Efficiency is a dependent variable i.e., it depends on the individual, environmental, and work conditions. In recent years, most offices pay attention to indoor environmental quality. Because the cost of hiring staff is higher than the cost of operating and maintaining a building. Thus, spending on improving the workplace is the most effective strategy to improve efficiency. This research seeks to study the effective factors on the efficiency of the employees through field studies. Environmental measurements of temperature, humidity, and carbon dioxide were measured in office buildings (from February 4, 2012, to March 5, 2012). Physical measurements showed that, as these parameters increased, efficiency decreased.Then employees fill out the questionnaires (N=328) in the offices of Kermanshah city. An indoor environment is effective for public health. Having healthy indoor environments is a definite right of people. The results of this research showed that satisfaction with the thermal condition, thermal comfort, optimal thermal condition, suitable workplace, and high quality of the workplace are factors influencing efficiency. Providing desired thermal conditions and increasing the quality of the workplace have the highest and lowest effects on the efficiency of employees.
Original Article
Tide, Wave and Hydro Power
A. Abazari
Abstract
The combination of offshore wind turbines and wave energy converters has recently been the focus of researchers. Many types of converters have been installed on the offshore platform in the design step, and the performance of these hybrid systems has been investigated. The oscillating water column converter ...
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The combination of offshore wind turbines and wave energy converters has recently been the focus of researchers. Many types of converters have been installed on the offshore platform in the design step, and the performance of these hybrid systems has been investigated. The oscillating water column converter is one of the most favorite and commercialized systems due to its efficiency and low maintenance cost. In the present study, a new design including the array of the oscillating water column in a circular arrangement around the spar-type platform is considered. The coupled governing equations are solved based on the simplified analytical approach through frequency domain analysis. The results show that the increase in the number of energy converters increases the total generated power, and consequently, the converters capture the vibrational energy of the spar platform. Therefore, the dynamic response of the spar decreases in the case with an array of energy converters which is one of the main objects of this hybrid system.
Original Article
Electricity Generation by Green Energy Sources
S. Poursheikhali
Abstract
In this paper, an energy harvesting assisted wireless network is considered where a source, contrary to the conventional networks, harvests its required energy via two independent energy channels. In addition, we assume a destination terminal, which receives interference signals along with the data transferred ...
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In this paper, an energy harvesting assisted wireless network is considered where a source, contrary to the conventional networks, harvests its required energy via two independent energy channels. In addition, we assume a destination terminal, which receives interference signals along with the data transferred by the source. In this model, the source is considered to scavenge energy from the destination's broadcasted signal and ambient interference signal. We model the energy and data channels via Rayleigh-Racian channel model. Then, the system outage probability is obtained after analyzing the outage probability of energy and data channels. Moreover, another scenario in which the source is assumed to harvest energy from only the destination terminal is investigated. Computer simulations are conducted to evaluate the effectiveness of the proposed approach, and the impacts of different system parameters on the system outage probability are investigated. The results indicate the outperformance of the scenario in which energy harvests via two channels compared to the case where only one energy harvesting channel exists. In addition, the overall system outage highly degrades when outage in energy channels decreases, especially in the first scenario.