@article { author = {Nabian Dehaghani, Mitra and Taher, Seyed Abbas and Dehghani Arani, Zahra}, title = {Coordinated control of hybrid AC/DC microgrids including PV and storage systems}, journal = {Energy Equipment and Systems}, volume = {9}, number = {4}, pages = {307-316}, year = {2021}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2021.248622}, abstract = {Coordinated control schemes are employed for both bidirectional DC/DC and AC/DC converters in this paper which are considered for connecting AC subgrid to DC one in hybrid AC/DC microgrids. Each subgrid consists of distributed generation units, which are photovoltaic systems working in maximum power point tracking mode, and local loads. Indeed, even though hybrid AC/DC microgrid has multiple merits over conventional microgrid, the interconnection of two different grids has some concerns such as complication, power management, and control. The coordinated control term in bidirectional AC/DC converter is formulated with regard to voltage of common bus and frequency of AC part. The common bus and DC subgrid voltages are utilized in the coordinated control term of bidirectional DC/DC converter. Modeling and simulating a hybrid AC/DC microgrid have been conducted in MATLAB/SIMULINK software. According to simulation results, the surveyed system can sustain its stability under the introduced coordinated control schemes. Hence, the proposed power management system based on coordinated control terms manage the power flow among DC and AC subgrids in addition to storage system.}, keywords = {photovoltaic systems,Hybrid AC/DC Microgrid,Coordinated Control,Power Management}, url = {https://www.energyequipsys.com/article_248622.html}, eprint = {https://www.energyequipsys.com/article_248622_687200467a4c03a7f054acc79c8707e6.pdf} } @article { author = {Zayer Kabeh, Kaveh and Haghighi Khoshkhoo, Ramin}, title = {Economic feasibility of small-scale gas to liquid technology in reducing flaring in Iran and case study of implementing the technology at the third South Pars refinery}, journal = {Energy Equipment and Systems}, volume = {9}, number = {4}, pages = {317-330}, year = {2021}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2021.248623}, abstract = {The comprehensive and reliable economic evaluation of using small-scale gas to liquid (GTL) technology for flaring reduction in Iran is needed to encourage policymakers and investors to consider the advantages of this technology. This study investigates the economic feasibility of using small-scale GTL technology for flaring reduction with ten different scenarios in Iran. Additionally, the possibility of using available facilities was considered in calculating the capital expenditure (CapEx) of plants to improve the reliability and accuracy of results. The effective economic factors are determined based on the announced policies and the data of technology developers. The results showed that using the small-scale GTL plants is economically justifiable in all conditions unless the oil price experiences a significant decline in the future years. In the existing status of Iran, the internal rate of return (IRR) of 37.93% was calculated for the proposed plant to reduce the high-pressure flaring in the Third South Pars Refinery. Moreover, relying on the available equipment which can be used in developing small-scale GTL plant increased the IRR of GTL plant by reducing the CapEx by 25%. Using small-scale GTL technology for flaring reduction is a profitable alternative technology to prevent the extensive damages of the dissemination of toxic substances in the air, and it provides tremendous financial opportunity for investors in Iran.}, keywords = {Small-Scale Gas-to-Liquid Technology,Economic Cvaluation,feasibility study,Flare Gas Recovery}, url = {https://www.energyequipsys.com/article_248623.html}, eprint = {https://www.energyequipsys.com/article_248623_8e39d9589a45c41dd58451f67b200d0f.pdf} } @article { author = {Arabhaghighi, Asadollah and Moghimi, Mahdi}, title = {Thermo-economic analysis and optimization of a novel combination of the solar tower power plant, Stirling engine, Reverse osmosis desalination, and proton exchange membrane electrolyzer}, journal = {Energy Equipment and Systems}, volume = {9}, number = {4}, pages = {331-349}, year = {2021}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2021.248624}, abstract = {This simulation study is aimed to investigate a multi-generation system including cycles of reverse osmosis (RO) desalination, Stirling engine, liquefied natural gas (LNG), a solar tower plant, and proton exchange membrane (PEM) electrolyzer to produce power, pure water, and hydrogen gas. All analyses were conducted to calculate the efficiency, exergy, energy, thermo-economic analysis, and total costs of this system. The sun radiation, liquefied gas flow rate, the temperature difference in the heat exchanger on the cold part of the Stirling engine are assumed as design parameters. Also, the effects of these parameters variation on hydrogen and pure water production were investigated. The power produced by the Stirling engine and LNG cycle of the proposed system is 8.18 MW (with the second law efficiency of 39.2%), which is used to produce 720 m3/h freshwater and 130.5 kg/h hydrogen gas. Sensitivity analysis was performed to determine the most effective variable on the operating conditions which indicated that solar radiation is the most effective design parameter. Finally, the total exergy efficiency and total cost rate were considered as two objective functions and the system was optimized by the Genetic algorithm. In optimized conditions, by the linear programming technique for multidimensional analysis of preference (LINMAP method), exergy efficiency becomes 43.29% and hydrogen production gets 7.6% increased.}, keywords = {Desalination,Hydrogen production,Exergy Analysis,Economic Analysis,genetic algorithm}, url = {https://www.energyequipsys.com/article_248624.html}, eprint = {https://www.energyequipsys.com/article_248624_783ddabe6b16688988cb40ed62c118cd.pdf} } @article { author = {Hajabdollahi, Mohsen and Shafiey Dehaj, Mohammad and Hajabdollahi, Hassan}, title = {Investigation of optimization algorithms and their operating parameters in different types of heat exchangers}, journal = {Energy Equipment and Systems}, volume = {9}, number = {4}, pages = {351-370}, year = {2021}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2021.248626}, abstract = {In this study, five different heat exchangers (HE) including, plate-fin (PFHE), fin tube (FTHE), rotary regenerator (RR), shell and tube (STHE) and gasket plate (GPHE) are optimized using four different algorithms including the binary genetic algorithm (BGA), real parameter genetic algorithm (RGA), particle swarm optimization (PSO) algorithm and the differential evolution (DE) algorithm. Verified codes are used for all heat exchangers and total annual cost (TAC) is considered as the objective function and heat exchanger configuration parameters are chosen as design parameters in all studied exchangers. RGA has the lowest insensitivity to the algorithm input parameters, or lowest relative standard deviation (RSD), for all studied heat exchangers. The best TAC in the GPHE, FTHE, PFHE, RR, STHE can be achieved in the points = (0,0.6), (0, 1.95), (0, 1.5), (0, 2.1), (0, 1.65) and < , > = (2.4,2.4), (1, 2.4), (3.25, 3.75), (3.15, 3), (2.6, 2.8) where  the lowest run- time and RSD are our basic requirements, respectively. The results also reveal that DE has the worst result in the case of RSD and GA has the worst result in the case of run-time. Finally, RGA is recommended for the optimization of different types of heat exchangers.}, keywords = {}, url = {https://www.energyequipsys.com/article_248626.html}, eprint = {https://www.energyequipsys.com/article_248626_f0ec099d08675f908613025c46d7f0df.pdf} } @article { author = {Shadidi, Behdad and Najafi, Gholamhassan}, title = {Impact of covid-19 on biofuels global market and their utilization necessity during pandemic}, journal = {Energy Equipment and Systems}, volume = {9}, number = {4}, pages = {371-382}, year = {2021}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2021.248655}, abstract = {In late 2019, the outbreak of a deadly Coronavirus shocked the world. Following the Covid-19 pandemic, governments were forced to enact a series of restrictive laws, including road and urban transportation. As a result of these restrictions, the consumption of fossil fuels in the world decreased and reduced the price and demand of these fuels. Because of the decline in this area, alternative fuels also faced serious challenges. Declining demand for alternative fuels has raised concerns about the development and future of these clean fuels. In this study, after presenting a quick look at biofuels' global markets, associated challenges ahead being examined in light of the declining demand and price of fossil fuels and biofuels. The results in this section showed that some social and economic constraints in the world are temporary due to the prevalence of Covid-19. As many countries reduced these restrictions in the second quarter of 2020, these limitation may be minimized shortly to zero with the discovery of vaccines and Covid-19 treatment. If it is supposed that the production of biofuels returns to its initial level in 2021, the development of biofuels should not be ignored because of the Covid-19. Obviously, in this case, the demand for biofuels will increase. According to new findings, the spread of coronavirus increases with air pollution. Therefore, the effects of coronavirus on air pollutants specifically NO2 and CO2 are investigated. The results revealed that the spread of coronavirus in 2020 has reduced NO2 emissions by 40-50% and CO2 emissions are also expected to be declined by 8%. This value is probably the largest reduction in CO2 emissions since 1900.  An effective solution to reduce air pollution is to develop the use of biofuels. At this time, the air pollution has been reduced due to a decrease in urban and road transportation. However, this pollution can be reduced by more development of biofuels to mitigate the spread of this deadly virus. Reduction in emissions is a result of declining social activity, rising unemployment, and severe economic problems.}, keywords = {COVID-19,Pandemic,Biofuels,Renewable Energy,Air pollution}, url = {https://www.energyequipsys.com/article_248655.html}, eprint = {https://www.energyequipsys.com/article_248655_1789e33369bd006ade7275831dca1f1a.pdf} } @article { author = {Dehghanzadeh Bafghi, Mojtaba and Sefid, Mohammad and Shamsoddini, Rahim and Salehizadeh, Amir Masoud}, title = {Investigation of the effect of Debye length change on electroosmotic flow with using constant density weakly compressible smoothed particle hydrodynamics method}, journal = {Energy Equipment and Systems}, volume = {9}, number = {4}, pages = {383-395}, year = {2021}, publisher = {University of Tehran}, issn = {2383-1111}, eissn = {2345-251X}, doi = {10.22059/ees.2021.248659}, abstract = {Electroosmotic is one of the four electrokinetic phenomena that is formed by applying an electric field to an ionized electrolyte near the charged dielectric surface. Due to the applying of this electric field change the arrangement of ions within the electrolyte, and eventually a region called the Electric double layer is formed near the surface. The thickness of this layer is approximated by the Debye length. In this study, the Because the Reynolds number in in microfluidic devices is usually very low. Therefore, achieving to sufficient mixing in electroosmotic microchannel flow has been a challenge. For this purpose, a non uniform distribution of surface potential for flow mixing is considered. This type of charge distribution is very efficient for mixing purposes by creating circulations in the microchannel. Lagrangian description is used to solve the governing equations. The method used in this research is the constant density weakly compressible particle hydrodynamics method. In order to improve the mixing, the effect of changing the Debye length has been analyzed. The results show that increasing the Debye length causes smaller vortexes to be produced and mixing efficiency is reduced.}, keywords = {}, url = {https://www.energyequipsys.com/article_248659.html}, eprint = {https://www.energyequipsys.com/article_248659_109a02049100a49f56e09f03ee57db29.pdf} }