Mohammad Ahmadzadehtalatapeh
Abstract
Air pre-cooling equipment is normally being employed in air-conditioning systems for pre-cooling the ambient outdoor air to enhance the air-conditioning systems performance. In this study, the potential of a passive water-to-air heat pipe based heat exchanger (HPHEX) for air pre-cooling purpose in air-conditioning ...
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Air pre-cooling equipment is normally being employed in air-conditioning systems for pre-cooling the ambient outdoor air to enhance the air-conditioning systems performance. In this study, the potential of a passive water-to-air heat pipe based heat exchanger (HPHEX) for air pre-cooling purpose in air-conditioning systems for the high cooling load demanding regions of Iran was investigated. To this end, effectiveness-NTU approach was employed to determine the thermal performance of the heat exchanger. Water-to-air HPHEX with different numbers of rows namely two, four, and six was studied to determine the heat transfer characteristics of the heat exchanger. The thermal performance of the water-to-air HPHEX was investigated under different operating conditions in terms of evaporator inlet air and condenser inlet water coil face velocities and temperatures. After determining the thermal performance of the water-to-air HPHEX, the air pre-cooling capability of the water-to-air HPHEX was explored hour-by-hour for the required months of the year by using TRNSYS software. Based on the simulations results, the water-to-air HPHEX shows an acceptable thermal performance under the operating conditions. In addition, studies showed that the water-to-air HPHEX has a significant capability for air pre-cooling, which makes it applicable to be implemented in the air-conditioning systems operating in south of Iran.
Renewable Energy Resources and Technologies
Sameer Hanna Khader; Abdel-Karim Khalid Daud
Abstract
This study proposes a novel approach to fast and direct determination of the Maximum Power Point (MPP) at any value of solar irradiation and cell temperature, without applying further mathematical processing to operate at that point. The current approach aims to reduce algorithm complexity, time consumption ...
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This study proposes a novel approach to fast and direct determination of the Maximum Power Point (MPP) at any value of solar irradiation and cell temperature, without applying further mathematical processing to operate at that point. The current approach aims to reduce algorithm complexity, time consumption during the iteration, and oscillation to reach the point at which the panel generates maximum possible power. For avoiding or eliminating these drawbacks, the chopper duty cycle (D) at which the panel-generated power should be the maximum is determined using the panel datasheet with respect to voltage and power at different irradiation rates (G). Mathematical equations are derived for MPP voltage and power at any value of solar irradiation using the manufacturer Photovoltaic (PV) specification. The simulation results obtained by MATLAB/SIMULINK platform showed that the power had a linear change, while the voltage had a nonlinear one with narrow variations. The yield duty cycle controls the Modified Single Ended Primary Converter (MSEPIC) that regulates the load voltage through a wide range below and above the rated panel voltage. The simulation results showed the fast response of chopper operation with a negligible starting time required by the MPPT algorithm, no duty cycle oscillation, and shorter iteration time. Furthermore, the conducted approach is validated based on the data published in a reputed journal, and the obtained results gave rise to new aspects that helped reduce dependency on conventional MPPT algorithms and, consequently, enhance the system response, efficiency and cost reduction.
Advanced Energy Technologies
Ashkan Zolriasatein; Zahra RajabiMashhadi; Majid Rezaei Abadchi; Nastaran Riahi Noori; Siamak Abyazi
Abstract
The crisis of contamination that leads to the accumulation of dust particles on insulation equipment and electrical insulators has disrupted the electricity grid. Electric discharge on infected insulators in wet conditions is a serious threat to the reliability of the grid, which can lead to grid failure ...
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The crisis of contamination that leads to the accumulation of dust particles on insulation equipment and electrical insulators has disrupted the electricity grid. Electric discharge on infected insulators in wet conditions is a serious threat to the reliability of the grid, which can lead to grid failure and blackout. In this regard, the importance of hydrophobic and dustproof coatings in the electricity industry has increased in recent years. In this paper, silica nanoparticles in the silicon rubber matrix were used to coat ceramic insulators to decrease the environmental impact of dust and moisture on the insulator’s coatings. One of the essential properties of these coatings is their hydrophobicity to prevent possible problems in power transmission. With this regard, nanocomposites were applied to 70 kN insulators and the tests were designed according to the available standards. The performance of these nanocoatings was evaluated by the implementation of electrical, salt fog, and hydrophobicity tests. Finally, the nanocomposite sample containing 3 wt % silica was recognized as the best one.
Mahsa Alimoradi; Mohsen Jahanshahi; Majid Peyravi
Abstract
Treatment of landfill leachate is challenging, due to its characteristics such as age, dumping place, composition and origin of wastes. For this reason, the application of hybrid processes is helpful for complete treatment of contaminants present in the leachates. The addition of membrane operations ...
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Treatment of landfill leachate is challenging, due to its characteristics such as age, dumping place, composition and origin of wastes. For this reason, the application of hybrid processes is helpful for complete treatment of contaminants present in the leachates. The addition of membrane operations to biological treatment technology offers new advantages for this method. For this aim, a bench-scale integrated process based on submerged aerobic MBR has been designed and fabricated. Also, Nanofiltration process as a post-treatment was used to upgrade MBR effluent. The results showed that the submerged UF-MBR system effectively removed biodegradable trace organic compounds with the average removal rate of about 75% at optimum food-to- microorganism (F/M) ratio (BOD basis) of 0.2 gBOD/g.d under a HRT of 24 h. The addition of NF process increased the treatment efficiency up to 98%. The effluent COD was reduced from 3500 mg/l to below 50 mg/l. Further, the effect of PAC addition was studied. NH3 –N, TKN and Heavy metals removal efficiency were obtained 97 ± 2%, 96 ± 2% and 99 ± 2%, respectively.
Renewable Energy Resources and Technologies
Tsutomu Dei; Hossen Iddi Kayumba; Julius Agaka Yusufu
Abstract
This research explores biomass gasification for power generation in rural areas of developing countries, utilizing a 20 kW U-flow-shaped gasification system developed at Ashikaga University. While small-scale power systems typically rely on reciprocating or modified diesel engines, which face issues ...
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This research explores biomass gasification for power generation in rural areas of developing countries, utilizing a 20 kW U-flow-shaped gasification system developed at Ashikaga University. While small-scale power systems typically rely on reciprocating or modified diesel engines, which face issues due to tar produced by biomass gasifiers, this study employed a piston-less rotary engine. Performance evaluations were conducted at various engine speeds and gasifier operational modes, demonstrating continuous power generation for approximately six hours. Improved maintenance of rotary engines could benefit rural users, with potential efficiency gains through thermal energy recovery, although tar filtration needs enhancement. The experimental findings reveal continuous power generation for approximately six hours under both operational conditions, with the closed-top operation outperforming the open-top counterpart in terms of power output. However, control over power output and gasifier temperatures is more straightforward in the open-top operation. Gasifier performance was assessed based on fuel consumption rate and system efficiency, with consumption rates varying by rotary engine speed, measuring 2.0 kWh/kg at 2800 rpm and 2.3 kWh/kg at 3200 rpm, and 2.9 kWh/kg at 3600 rpm. Cold gas efficiency of the U-shaped gasifier was 63.4%, and energy conversion efficiency reached 9.4% at 2800 rpm operation. At 3200 rpm operation, cold gas efficiency improved to 79.8%, but energy conversion efficiency decreased to 7.3%. The rotary engine's energy conversion efficiency was lower than that of a gas engine. Nonetheless, if the rotary engine reduces maintenance needs, it could benefit rural users. Efficiency can be improved through thermal energy recovery.
Renewable Energy Resources and Technologies
Setare Peirow; Fatemeh Razi Astaraei; Amir Ali Saifoddin; Hossein Yousefi
Abstract
The issue of power supply in hospitals is of special importance because of its direct effect on people's health conditions and vital treatment and care measures. Hospitals are among buildings with high energy consumption. The possibility of using renewable sources in their energy supply is one of the ...
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The issue of power supply in hospitals is of special importance because of its direct effect on people's health conditions and vital treatment and care measures. Hospitals are among buildings with high energy consumption. The possibility of using renewable sources in their energy supply is one of the issues and challenges that specialists encounter. This paper discusses the possibility of installing a small solar power generation unit on a hospital rooftop to improve the quality of power supply systems. The case study is a hospital located in Tehran, Iran. For this purpose, the hospital energy system was modeled with the Design-Builder software. The obtained results were validated based on the actual consumption of the model specified in the hospital energy bills. According to the modeling step results, the annual consumption of the current energy system was 3.08 GWh of electricity and 4.23 GWh of gas. In the second step, a renewable power generation unit consisting of photovoltaic panels and battery was designed for the hospital's roof using PVsyst software. The designed power generation unit could produce 132 MWh of solar energy per year, of which 85 MWh may be sold to the main grid. The techno-economic and environmental feasibility study for the proposed system was performed using HOMER Pro software. The evaluation results revealed that considering the 20-year lifetime of the project, the proposed system achieved a lower energy cost and lower net present cost than the current system. Environmental assessment of the model by considering emission penalty indicated that the proposed system emitted fewer pollutant gases into the environment than the current system. Sensitivity analysis was also applied to investigate the effect of discounting and diesel fuel price variation on the system’s energy cost. According to the results, a 4 % increase in the discount rate leads to a 14 % growth in the cost of energy for the project. Also, there was a direct relation between enhancement of the expected inflation rate and raising the net present cost of the project.
Renewable Energy Resources and Technologies
Ali Nazari; Morteza Hosseinpour; Mahdi Rezaei
Abstract
In this study, the impact of digestate treatment after Anaerobic Digestion (AD) process in two scenarios is analyzed in the case of an industrial diary unit in the United States. The first scenario involves production of liquid fertilizer and compost, while the second scenario lacks such a treatment ...
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In this study, the impact of digestate treatment after Anaerobic Digestion (AD) process in two scenarios is analyzed in the case of an industrial diary unit in the United States. The first scenario involves production of liquid fertilizer and compost, while the second scenario lacks such a treatment process. Aspen Plus is used to simulate the AD process and evaluate the general properties of biogas and digestate. The results of technical analysis show insignificant changes in the net power production from the CHP unit in Scenario 1. The economic analysis, however, indicates the necessity of digestate treatment for AD systems to be profitable. Furthermore, the results of environmental analysis indicate the mitigation of about 93.4 kilotonnes of greenhouse gas (GHG) emissions in Scenario 1, while AD in Scenario 2 saves only 12 kilotonnes of GHG emissions. In other words, digestate treatment has a more significant environmental impact than the power production and its profitability from CHP unit. The reason could be attributed to the enormous consumption of energy during the production of chemical fertilizers where the digestate treatment process (scenario 1) offsets the utilization of chemical fertilizers in the agriculture industry.
Renewable Energy Economics, Policies and Planning
Mohammad Amin Mirzaei; Morteza Nazari-Heris; Behnam Mohammadi-Ivatloo; Mousa Marzband; Amjad Anvari-Moghaddam
Abstract
The significant penetration rate of wind turbines in power systems made some challenges in the operation of the systems such as large-scale power fluctuations induced by wind farms. Gas-fired plants with fast starting ability and high ramping can better handle natural uncertainties of wind power compared ...
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The significant penetration rate of wind turbines in power systems made some challenges in the operation of the systems such as large-scale power fluctuations induced by wind farms. Gas-fired plants with fast starting ability and high ramping can better handle natural uncertainties of wind power compared to other traditional plants. Therefore, the integration of electrical and natural gas systems has great potential of enhancing the flexibility of power systems to incorporate more renewable power sources such as wind turbines. In this area, the uncertainty associated with wind speed has a meaningful impact on the optimal management of the generation units in power grids. This study proposes a stochastic market-based model for clearing of energy in interconnected power and gas systems with integration of wind power. Stochastic programming is developed for studying the uncertainty of wind power production using a normal distribution function in a two-stage model. It should be remarked that the proposed two-stage model covers the uncertainty of wind power generation and load demand in real-time dispatch determining the hourly scheduling of units in the first stage. It is expected that the operation cost of the integrated networks, local marginal pricing of the gas and power, and the load shedding will be increased by an increase in the residential gas load. The investigations showed a 4.2% increase of total operation cost of the integrated power and gas system by a 5% increase in the residential gas load.
Renewable Energy Resources and Technologies
Reza Rahimi; Alireza Shirneshan
Abstract
In this study, the effects of hydrogen and hydroxygen additions and oxygen enrichment on the emission characteristics of a gasoline engine (EF7) were investigated and compared with each other. The simulation was launched by GT-Power at different engine speeds with 5 % to 15 % volume fractions for both ...
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In this study, the effects of hydrogen and hydroxygen additions and oxygen enrichment on the emission characteristics of a gasoline engine (EF7) were investigated and compared with each other. The simulation was launched by GT-Power at different engine speeds with 5 % to 15 % volume fractions for both of oxygen and hydrogen enrichment and 4.5 % to 9 % volume fractions of hydroxygen addition in the intake gas, respectively. In addition, the model was validated by experimental data. The results showed that CO emission decreased from 11 % to 28 % in the hydrogen-enrichment condition. Moreover, carbon monoxide production was reduced from 28 % to 42 % for hydroxygen addition, and this pollutant emission experienced a reduction of 51 % to 67 % for oxygen enrichment. According to the results, HC emission decreased up to 13% in the hydrogen-enriched air condition, and it was reduced from 30 % to 43 % during hydroxygen addition. In addition, HC emission experienced maximum reduction of 47 % to 68 % during oxygen addition. On the other hand, there was an opposite trend for NOx emission. It was observed that NOx emission increased by around 40 % and 75 % for hydrogen and hydroxygen enrichment, respectively. Moreover, nitrogen oxides enhanced 2 to 5 times during oxygen enrichment, compared to that in the normal condition of the engine. Results showed that 15 % oxygen enrichment and 9 % hydroxygen enrichment had significant effect on the reduction of HC and CO emissions, and oxygen enrichment had greater effect on the rise of NOx emissions than hydrogen and hydroxygen additions.
Saeed Edalati; Mehran Ameri; Masoud Iranmanesh
Abstract
In this study, an artificial neural network based model for prediction of solar energy potential in Kerman province in Iran has been developed. Meteorological data of 12 cities for period of 17 years (1997–2013) and solar radiation for five cities around and inside Kerman province from the Iranian ...
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In this study, an artificial neural network based model for prediction of solar energy potential in Kerman province in Iran has been developed. Meteorological data of 12 cities for period of 17 years (1997–2013) and solar radiation for five cities around and inside Kerman province from the Iranian Meteorological Office data center were used for the training and testing the network. Meteorological and geographical data were used as inputs to the network, while the solar radiation intensity was used as the output of the network. The results show that the correlation coefficients between the predictions and actual global solar radiation intensities for training and testing datasets were higher than 97%, suggesting a high reliability of the model for evaluating solar radiation in locations where solar radiation data are not available. The predicted solar radiation values are illustrated in the form of maps that were made by ArcGIS.
Ehsan Hosseini; Ehsan Aghadavoodi; Ghazanfar Shahgholian; Homayoun Mahdavi-Nasab
Abstract
The effective utilization of wind energy conversion system )WECS( is one of the most crucial concerns for the development of renewable energy systems. In order to achieve appropriate wind power, different pitch angle methods are used. Recurrent Adaptive Neuro-Fuzzy Inference System (RANFIS) is utilized ...
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The effective utilization of wind energy conversion system )WECS( is one of the most crucial concerns for the development of renewable energy systems. In order to achieve appropriate wind power, different pitch angle methods are used. Recurrent Adaptive Neuro-Fuzzy Inference System (RANFIS) is utilized in this paper in a new effective design to improve the performance of classical and adaptive Proportional Integral (PI) controllers applied for the pitch control purposes. Adaptive-online performance and high robustness coverage are the main advantages of the suggested controller. The effectiveness of the proposed method is verified by a simplified two-mass wind turbine model and a detailed aero-elastic wind turbine simulator (FAST7). At any given wind speed, the proposed controller has outperformed PI, Adaptive Neuro-Fuzzy Inference System (ANFIS), and RANFIS based controllers, reducing the mechanical stress of drive train while presenting suitable aerodynamic power tracking and maintaining the rotational speed of the rotor under the rated value.
Advanced Energy Technologies
Negin Maftouni; Minoo Askari
Abstract
Both energy and environmental criticisms push a society toward energy-efficient buildings with green technologies. Green roofs are of significant importance due to their remarkable role in decreasing the thermal loads ofbuildings, especially in summer, and also in sound insulation. Here in, the thermal ...
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Both energy and environmental criticisms push a society toward energy-efficient buildings with green technologies. Green roofs are of significant importance due to their remarkable role in decreasing the thermal loads ofbuildings, especially in summer, and also in sound insulation. Here in, the thermal loads of a residential building were calculated, and then, an optimized green roof was designed for it in three different cities of Tehran, Rasht, and Tabriz. The energy saving was analyzed in each case, and proper plants and roof thickness were selected to achieve both comfortable air conditioning and energy optimization. It is also important to use water resources in an optimized manner. Considering the annual mean rain magnitude, here, a suitable system is designed to harvest rainwater for watering the plants. Results indicate that a sedum grass-based green roof with the thickness of 10 cm leads to a 21.3 % reduction in the annual total thermal loads in Tehran; one with thickness of 8 cm in Tabriz will result in a 11.7 % thermal load reduction per year; a green roof with 9 cm thickness in Rasht, Iran shows 13.2 % energy saving per year. Therefore, Tehran is the best option here to integrate the green roof into the structure of the building. The patterns of the obtained data indicate that the reduction of cooling loads is more noticeable when implementing a green roof in comparison with heating loads. Moreover, it has been revealed that harvested rainwater is sufficient to support about 72 % of required water in Tehran, 81 % of it in Tabriz, and 93 % in Rasht.
Advanced Energy Technologies
Haleh Sadeghi; Iraj Mirzaei; Shahram Khalilaria; Sajad Rezazadeh; Mojtaba Rasouli Gareveran
Abstract
Among the renewable energy systems, fuel cells are of special significance about which more investigation is required. The principal goal of the present study is considering the effect of the geometry change on the fuel cell's performance. In this paper, a three-dimensional model of proton exchange membrane ...
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Among the renewable energy systems, fuel cells are of special significance about which more investigation is required. The principal goal of the present study is considering the effect of the geometry change on the fuel cell's performance. In this paper, a three-dimensional model of proton exchange membrane fuel cell has been numerically simulated with conventional cubic geometry. Afterwards, two brand-new cylindrical models have been proposed to compare and select the best model. The governing equations include mass, momentum, energy, species and electrical potential, which are discretized and solved using the method of computational fluid dynamics. The results obtained from numerical analyses were validated with those from experimental data, which showed acceptable agreement. For the above-mentioned models, changes in the species mass fraction, temperature, electric current density, and over-potential were analyzed in more detail. The results reveal that, in all three models, by decreasing the amount of cell voltage differences between the anode and the cathode, higher current density is produced, which leads to high input species consumption and, consequently, more water and heat generation. On the other hand, the four-channel cylindrical model is more efficient than the other two models and has shower pressure drop due to its shorter pathway. The results illustrated that, at V=0.6 )V(, the amount of the output current density in the four-channel model increased by approximately 18.4 %, compared to that in the other two models. Further, in this model, the material used in bipolar plates is less than that in the other models.
Vajiheh Sabeti; Fateme Ahmadi Boyaghchi
Abstract
This paper deals with a multi-objective optimization of a novel micro solar driven combined power and ejector refrigeration system (CPER). The system combines an organic Rankine cycle (ORC) with an ejector refrigeration cycle to generate electricity and cold capacity simultaneously. Major thermodynamic ...
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This paper deals with a multi-objective optimization of a novel micro solar driven combined power and ejector refrigeration system (CPER). The system combines an organic Rankine cycle (ORC) with an ejector refrigeration cycle to generate electricity and cold capacity simultaneously. Major thermodynamic parameters, namely turbine inlet temperature, turbine inlet pressure, turbine back pressure, and evaporator temperature are selected as the decision variables. Three objective functions, namely the energetic efficiency, exergetic efficiency and cost rate of products are selected for optimization. NSGA-II and MOPSO are employed and compared, to achieve the final solutions in the multi-objective optimization of the system operating. It is found that the values of the energetic and exergetic efficiencies increase within 27.7% and 26.1%, respectively and the cost rate of products decreases by about 32.7% with respect to base case.
Advanced Energy Technologies
Ghazanfar Shahgholian
Abstract
Distributed flexible ac transmission system (D-FACTS) is a light-weight version of FACTS, which it is easily allocated and costs less than flexible ac transmission system (FACTS) devices. They have potential benefits to improve the system stability and improvement in power quality in microgrid (MG). ...
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Distributed flexible ac transmission system (D-FACTS) is a light-weight version of FACTS, which it is easily allocated and costs less than flexible ac transmission system (FACTS) devices. They have potential benefits to improve the system stability and improvement in power quality in microgrid (MG). The integration of distributed energy sources, loads, electrical energy storage devices, and electronic power devices, as well as the operation of microgrids in connected or island-connected modes has expanded their use. It is a small main grid that can generate electricity when disconnected from the main network. In addition, microgrids reduce the high investment costs required to upgrade the network. The application of DFACTS devices for improving the microgrid operation has been investigated by some researches. This paper provides a review of impact and role of various DFACTS devices in the function of microgrids, which has been reported in recent years in various pieces of the literature. DFACTS devices with their properties are described. Finally, a useful reference and framework for the study is provided for future expansion of DFACTS devices so as to improve the performance of the microgrid.
Hossein Ghadamian; Hassan Ali Ozgoli; Mojtaba Baghban Yousefkhani; Foad Farhani
Abstract
Regenerative Fuel Cell (RFC) systems are used for the enhancement of sustainable energy aspect in conventional fuel cells. In this study, a photovoltaic-electrolyzer-fuel cell integrated cycle has been presented. The proposed system has been designed as a novel approach for alleviating the ...
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Regenerative Fuel Cell (RFC) systems are used for the enhancement of sustainable energy aspect in conventional fuel cells. In this study, a photovoltaic-electrolyzer-fuel cell integrated cycle has been presented. The proposed system has been designed as a novel approach for alleviating the restrictions on energy streams in the RFC systems. Modeling of the system has been performed from the mass and energy point of view, based on both theoretical and practical procedures. To generate electricity from hydrogen, a proton exchange membrane fuel cell, integrated with an electrolyzer system which works by solar energy, has been used. Optimized results of required photovoltaic area have shown significantdifferences between theoretical and practical approaches. Moreover, all efficiencies of two scenarios including total efficiency have been indicated and analyzed. The main advantage of this system in comparison with single solar systems, is generation of internal energy of about 2.3 kW for producing 1 kW electricity by the fuel cell.
Advanced Energy Technologies
Seyed Amir Hassan Bathaei; Masoud Iranmanesh; Hossein Amiri; Hajir Kourki
Abstract
Thermal Energy Storage (TES) for solar thermal systems has attracted great attention because of the intermittent availability of solar energy. In the current paper, new combinations of several Phase Change Materials (PCMs) including a type of paraffin and some mineral compounds like ammonium nitrate ...
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Thermal Energy Storage (TES) for solar thermal systems has attracted great attention because of the intermittent availability of solar energy. In the current paper, new combinations of several Phase Change Materials (PCMs) including a type of paraffin and some mineral compounds like ammonium nitrate and magnesium nitrate hexahydrate were exanimated and their thermo-physical properties were compared. This study targets solar heating systems at different temperature intervals for the TES. Another new approach of this study is to determine the effect of Multi-Wall Carbon Nanotubes (MWCNTs) with two diameters (D) of 8 and 10-20 nm on paraffin's thermophysical property to improve these properties. An innovative method was used to measure Electrical Conductivity (EC) as it is easier to measure than thermal conductivity (K) to study the effect of nanoparticles on PCM behavior. The results showed that the highest values of improvement over paraffin properties were related to 5% nanoparticle additive for both nanoparticle diameters among the percentages studied. The addition of 5 % nanoparticles with 10-20 nm and 8 nm to paraffin at 25 ° C increased heat conductivity by 142% and 156%, respectively. The addition of nanoparticles to paraffin improved EC several times such that a diameter of 8 nm made a 300% increase in EC compared to 10-20 nm.
Somayeh Sarirchi; S. Rowshanzamir
Abstract
Nowadays, proton exchange membrane fuel cells (PEMFCs) are the most promising green energy conversion devices for portable and stationary applications. Traditionally, these devices were based onperfluoro-sulfonic acid electrolytes membranes, given the commercial name Nafion. Nafion is the mostused electrolyte ...
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Nowadays, proton exchange membrane fuel cells (PEMFCs) are the most promising green energy conversion devices for portable and stationary applications. Traditionally, these devices were based onperfluoro-sulfonic acid electrolytes membranes, given the commercial name Nafion. Nafion is the mostused electrolyte membrane till now; because of its high electrochemical properties such as high protonconductivity, good mechanical and chemical stability at fuel cell conditions, and .... However, its high cost, reducing the performance at temperature higher than 80℃, and low humidity are the majorproblems. Hydrocarbon polymers are encouraging alternative to Nafion, since they show the same oreven superior performance than Nafion at high temperature and low humidity by some modifications. Numerous researches confirmed that Sulfonated poly ether ether ketone (SPEEK) is a promising PEMbecause of its low-cost, low fuel cross over, and acceptable thermo-mechanical stabilities. However,suitable proton conductivity in SPEEKs is depending on the high degree of sulfonation (DS), whichcould deteriorate the mechanical properties of SPEEK membranes progressively at the high level. Toovercome this dilemma, various SPPEK-based hybrid/blend membranes are synthesized, and theeffects of the introduced fillers on their performance are investigated. The introduced inorganicparticles to the polymer membranes might be silica, zirconia, titania, heteropolyacids, carbonnanotubes, and.... Enhanced proton conductivity, water retention at high temperatures, and higherelectrochemical properties are mentioned as some advantages of incorporating inorganic material intothe polymer matrix. High thermo-mechanical resistance and electrochemical activities are supplied byinorganic moieties, while the organic parts supply plasticity and easier ductility at the low temperature.Indeed, SPEEK blends have a good potential to alter Nafion at the high temperature and/or relativelylow humidity. In this paper, the last advances in progress of SPEEK-based organic/inorganiccomposite membranes that perform truly under fuel cell conditions are discussed.
Saber Sadeghi; Mehran Ameri
Abstract
This study shows the design of a new hybrid power generation system, photovoltaic panel (PV)–coupled solid oxide fuel cell (SOFC) and gas turbine (GT)–electrolyser. Three objectives (cost, pollutant emissions, and reliability), which are usually in conflict, are considered simultaneously. ...
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This study shows the design of a new hybrid power generation system, photovoltaic panel (PV)–coupled solid oxide fuel cell (SOFC) and gas turbine (GT)–electrolyser. Three objectives (cost, pollutant emissions, and reliability), which are usually in conflict, are considered simultaneously. The design of a hybrid system, considering the three mentioned objectives, poses a very complex problem of optimization. A multi-objective optimization method (PESA) is considered to obtain the best combinations for the hybrid system. In this work, the effect of panel s angle change and SOFC-GT fuel type are considered too. In order to study the effect of fuel price, this study is done about two fuel prices: Iran fuel price and international fuel price.
Akram Abdulameer Abbood Al-Khazzar; Aseel Jamal Khaled
Abstract
In Iraq, solar radiation field measurements are available only for very ...
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In Iraq, solar radiation field measurements are available only for very limited locations such as some universities and research centers. This article reviews and compares the measured monthly averaged global solar radiation data for Iraqi provinces and cities available in the literature and studies over the internet especially Google Scholar, Research Gate and IASJ. The selected locations are Baghdad, Mosul, Tikrit, Rutba, Nasiriya, Kirkuk, Haditha, and Najaf. The measured data is compared with the corresponding available satellite data from NASA and Meteonorm software and Root mean square error is calculated to test NASA and Meteonorm performance. The review results show that the maximum GSR in July in Haditha (8.3 kWhr/m2) while the minimum is in Mosul city in December (1.68 kWhr/m2). Baghdad measured monthly mean is about 5.20 kWhr/m2.
Renewable Energy Resources and Technologies
Nemat Keramat Siavasha; Gholamhasan Najafi; Teymour Tavakoli; Barat Ghobadian; Esmail Mahmoodi
Abstract
Ducted wind turbines are a kind of small wind turbine having a diffuser or any other shape around the rotor which increases the air flow through the blades and absorbs more power. In the present study, a small wind turbine was ducted with a relatively simple ring and its performance was investigated ...
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Ducted wind turbines are a kind of small wind turbine having a diffuser or any other shape around the rotor which increases the air flow through the blades and absorbs more power. In the present study, a small wind turbine was ducted with a relatively simple ring and its performance was investigated in a wind tunnel. The duct is shaped using rolling steel sheets on a sloping surface and finally fabricated in double-glazed surfaces. The turbine utilizes polyester resin glass fiber-armed composite hollow blades. Bare turbine produces 165 watts in its highest power generation mode which can reach 282 watts when it is ducted. The evaluation of the system in the wind tunnel showed that the power generation of the ducted system compared to a conventional turbine was 14 % higher on average. Furthermore, the rotor speed of the ducted turbine was 45 % higher than the bare one which increases the tip speed ratio (TSR). In this study, TSR increment raised the absorbed power in the developed wind turbine.
Advanced Energy Technologies
Maryam Keshavarz; Davod Mohebbi-Kalhori; Vajihe Yousefi
Abstract
Response surface methodology is employed to statistically identify the significance of three parameters of separator assembly arrangement, wastewater flow rate, and relative flow patterns of anode and cathode influencing the generation of power and coulombic efficiency of Microbial Fuel Cells (MFCs). ...
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Response surface methodology is employed to statistically identify the significance of three parameters of separator assembly arrangement, wastewater flow rate, and relative flow patterns of anode and cathode influencing the generation of power and coulombic efficiency of Microbial Fuel Cells (MFCs). Three different assemblies of Nylon-Cloth (NC), artificial rayon cloth as Absorbent Layer (AL), and J-Cloth (JC) were investigated as proton exchange mediums instead of common expensive polymeric membranes. Statistical analyses (ANOVA) revealed that although the addition of the AL after the JC layer had no significant impact on the enhancement of maximum power density, it could improve the coulombic efficiency of the MFCs by 15 %, owing to the crucial impact of oxygen permeability control between the MFC chambers. In the counter-current flow pattern, higher trans-membrane pressure and more oxygen concentration differences diminished the MFC performance and marked the importance of efficient separator layer arrangement, compared to co-current influents. The maximum power density of 285.89 mW/m2, the coulombic efficiency of 4.97 %, and the internal resistance of 323.9 Ω were achieved for the NC-JC-Al arrangement in the co-current mode along with the flow rate of 6.9 ml/min. The higher the flow rate of influent wastewater, the higher the performance of the MFCs.
Renewable Energy Resources and Technologies
Aondoyila Kuhe; Victor Terhemba Achirgbenda; Mascot Agada
Abstract
The optimum design of solar energy systems strongly depends on the accuracy of solar radiation data. However, the availability of accurate solar radiation data is undermined by the high cost of measuring equipment or non-functional ones. This study developed a feed-forward backpropagation artificial ...
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The optimum design of solar energy systems strongly depends on the accuracy of solar radiation data. However, the availability of accurate solar radiation data is undermined by the high cost of measuring equipment or non-functional ones. This study developed a feed-forward backpropagation artificial neural network model for prediction of global solar radiation in Makurdi, Nigeria (7.7322 N long. 8.5391 E) using MATLAB 2010a Neural Network toolbox. The training and testing data were obtained from the Nigeria metrological station (NIMET), Makurdi. Five meteorological input parameters including maximum and temperature, mean relative humidity, wind speed, and sunshine hour were used, while global solar radiation was used as the output of the network. During training, the root mean square error, correlation coefficient and mean absolute percentage error (%) were 0.80442, 0.9797, and 3.9588, respectively; for testing, a root mean square value, correlation coefficient, and mean absolute percentage error (%) were 0.98831, 0.9784, and 5.561, respectively. These parameters suggest high reliability of the model for the prediction of solar radiation in locations where solar radiation data are not available.
Environmental Impacts and Sustainability
Bahram Hosseinzadeh Samani; Marziyeh Ansari Samani; Rahim Ebrahimi; Zahra Esmaeili; Ali Ansari Ardali
Abstract
Due to limited oil reserves, the rising world fuel prices and environmental problems caused by the use of fossil fuels increase the tendency to use alternative fuels such as biodiesel and bioethanol. In this study, the evaluation of energy and exergy flow from seed planting to final production of biodiesel ...
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Due to limited oil reserves, the rising world fuel prices and environmental problems caused by the use of fossil fuels increase the tendency to use alternative fuels such as biodiesel and bioethanol. In this study, the evaluation of energy and exergy flow from seed planting to final production of biodiesel from rapeseed oil was carried out. Biodiesel production from rapeseed was made in three main phases: farm, oil extraction, and industrial biodiesel production. Initially, the input and output variables for rapeseed production were collected through questionnaires from 30 rapeseed farms in Khuzestan province, Iran. Thus, the amount of energy input and output to the field for rapeseed was estimated to be 12826.98 and 22195 MJ/ha, respectively. The highest energy consumption is related to chemical fertilizers with 65 % share of other inputs. Input and output exergy rates were obtained as 3933.494 and 22603.39 MJ/ha, respectively, and the highest exergy consumption related to diesel fuel with 58 % share of other inputs. At the biodiesel production stage, the input energy and output energy were 156.95 MJ and 41.88 MJ, respectively, and the highest amount of electricity consumed was 91.02 MJ. The total amount of exergy in the production of biodiesel and the output exergy was 48.412 MJ and 64.568 MJ, respectively. In this study, the effects of alcohol-to-oil molar ratio, ultrasound power (W), catalyst concentration (w/w %), and the reaction time (min) on methyl ester yield using response surface methodology based on Box Behnken experimental design in the Design Expert software were investigated. Finally, gas emissions were studied at the planting and biodiesel production stages, and the resultsshowed that the highest greenhouse gas emissions at the planting stage were related to chemical fertilizers and alcohol production.
Renewable Energy Resources and Technologies
Mirmahdi Seyedrahimi-Niaraq; Tohid Nouri
Abstract
Geothermal energy is a non-carbon renewable source from the earth's internal energy. This energy is considered reliable today and has a high potential to reduce the threat of climate change. The main factor that any investor wants to invest in any natural energy source is the resulting economy. In the ...
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Geothermal energy is a non-carbon renewable source from the earth's internal energy. This energy is considered reliable today and has a high potential to reduce the threat of climate change. The main factor that any investor wants to invest in any natural energy source is the resulting economy. In the case of geothermal energy, factors that increase the risk of investing in this sector include higher investment costs, longer payback times than other renewable power plants, and the uncertainty of the size and quality of the resources before the completion of the well drilling operation. The average payback time in geothermal energy systems is 5.7 years, longer than wind and solar energy. According to these factors, the risk of investing in geothermal technology increases. On the other hand, due to its independence from oil and gas, it increases a country's energy security, helps to create direct, indirect, and induced employment, and affects other economic sectors. Also, unlike renewable wind and solar energies, it is not dependent on climate change; therefore, it has higher reliability than other renewable energies. Also, by combining this energy with other renewable energies, its performance can be optimized. For example, in an optimal geothermal-solar hybrid power plant, solar energy provides 48 % of the total energy. In this case, the Levelized Cost of Energy (LCOE) is reduced from 225 $ per MWh (only with geothermal source) to 165 $ per MWh. In this study, while studying the economic effects of geothermal systems, an attempt has been made to address the challenges in this field and present the policies implemented in some countries. It is implied that by providing incentive policies and an appropriate roadmap, it is possible to help attract investment in the operation of geothermal systems.
