Renewable Energy Resources and Technologies
Sina Eterafi; Shiva Gorjian; Majid Amidpour
Abstract
In this study, the effect of covering the aperture area of a conical cavity receiver with an ultra-white glass on operational parameters of a Parabolic Dish Collector (PDC) was numerically and experimentally investigated under climate conditions of Tehran (35.44° N latitude and 51.10° longitude). ...
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In this study, the effect of covering the aperture area of a conical cavity receiver with an ultra-white glass on operational parameters of a Parabolic Dish Collector (PDC) was numerically and experimentally investigated under climate conditions of Tehran (35.44° N latitude and 51.10° longitude). The main components of the experimental setup include a dish reflector, a conical cavity receiver, Heat Transfer Fluid (HTF), hydraulic and cooling cycle, and a sun tracker. For this purpose, a conical cavity receiver with an ultra-white glass cover on its aperture was numerically modeled in Fortran software. During the evaluation, environmental parameters including ambient temperature, solar radiation, and wind speed were considered as inputs of the model. The results revealed fair agreement between the numerical and experimental data with the maximum error of approximately 4.63 % and 7.89 % for receivers with and without the glass cover on the aperture, respectively. For a steady-state analysis, the mean values of useful energy ( ) absorbed by the receiver were calculated as 1,253.25 W and 987.68 W, while thermal efficiency ( ) of the receiver was calculated as 52.61 % and 40.69 % for receivers with and without glass cover, respectively. The results revealed that both and followed a similar trend of the variations in the HTF’s temperature between the inlet and outlet of the receiver. Also, the overall heat loss coefficient ( ) and the collector heat removal factor ( ) were calculated as 420.76 W/m2°C and 0.62 for the conical cavity receiver with the glass cover.
Renewable Energy Resources and Technologies
Najmeh Salehi; Arash Mirabdolah Lavasani; Ramin Mehdipour; Mohammad Eftekhari Yazdi
Abstract
One of the best and most important types of concentrating solar power plants is the linear Fresnel collector. The thermal performance and application of absorber in a solar power plant can be enhanced using direct steam generation technology. A particular discrepancy between the present study and others ...
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One of the best and most important types of concentrating solar power plants is the linear Fresnel collector. The thermal performance and application of absorber in a solar power plant can be enhanced using direct steam generation technology. A particular discrepancy between the present study and others lies in our attempt at applying a new method for calculating critical heat flux based on Look-up Table. In the current study, effects of nanofluid on the length of the critical heat flux and convection heat transfer coefficient were investigated. The nanoparticles considered in this study were aluminum, silver, nickel, and titanium dioxide at concentrations of 0.01, 0.1, 0.3, 0.5, 1 and 2 %. Modeling results revealed that the heat transfer coefficient increased upon enhancing the volumetric concentration of nanoparticles, thereby improving this coefficient at 2 vol. % nickel nanoparticles, which was 10.6 % above the value of pure water. On the other hand, thermal efficiency was enhanced when nickel nanoparticles were dispersed in pure water such that increase rates of thermal efficiency equaled 11.2, 10.8 and 11.3 % in the months of June, July, and August, respectively, when the volume concentration of nanoparticles was 0.5 %.
Renewable Energy Resources and Technologies
Daryoosh Borzuei; Seyed Farhan Moosavian; Abolfazl Ahmadi; Rouhollah Ahmadi; Kourosh Bagherzadeh
Abstract
Energy plays a vital role in all human life activities. Due to the problems caused by fossil fuels in recent decades such as global warming, greenhouse gas emissions, ozone depletion, etc., the use of renewable and clean energy has been considered. An experimental facility for the acquisition of reliable ...
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Energy plays a vital role in all human life activities. Due to the problems caused by fossil fuels in recent decades such as global warming, greenhouse gas emissions, ozone depletion, etc., the use of renewable and clean energy has been considered. An experimental facility for the acquisition of reliable data from Parabolic Trough Solar Collectors (PTCs) was established to develop a robust analytical model. A wide range of Heat Transfer Fluid (HTF) flow rates (0.0372-0.1072 kg/s) and solar radiation (400-900 W/m2) were used to determine PTC parameters such as the outlet temperature of HTF loss and temperature distribution. Vacuum conditions in the receiver were considered effective in terms of thermal efficiency. Also, three types of HTF including two oil fluids (Syltherm 800 and S2) and water were examined. The temperature distribution showed that when Syltherm 800 or S2 passed through the absorber tube, the outlet temperature was higher than water: 2.84 % for Syltherm 800 and 3.72 % for S2. Since the absorber tube temperature was much higher than water, the heat loss in this condition was considered for oil HTF. Of note, the results demonstrated that use of the vacuum tube could diminish heat loss for the oil HTF. The effect of solar intensity increases from 600 W/m2 to 900 W/m2 on the maximum temperature of the receiver tube indicated that when Syltherm 800 was used as an HTF, this temperature increased by 35.1 % (from 167 °C to 219 °C), while this percentage was 32.7 % and 6.8 % for S2 and water, respectively.
Renewable Energy Resources and Technologies
Sepideh Rahmati Dehkordi; Mehdi Jahangiri
Abstract
In Iran, due to the problems and constraints of fossil fuels and the need to maximize the use of solar potential, one of the best ways is the application of photovoltaic systems integrated with buildings. Due to the significant dependence of solar cell performance on the availability of radiation, it ...
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In Iran, due to the problems and constraints of fossil fuels and the need to maximize the use of solar potential, one of the best ways is the application of photovoltaic systems integrated with buildings. Due to the significant dependence of solar cell performance on the availability of radiation, it is necessary for architects to have an accurate assessment of the amount of electricity produced in different conditions. Therefore, in the present work, using HOMER software, the energy-econo-Enviro (3E) potential of a Building Integrated Photovoltaic (BIPV) in Abadan was studied. The effect of slope and azimuth of solar cells as well as cloudiness and system losses were investigated using sensitivity analysis. The results showed that the PV-grid system was the most economical option and after the azimuth angle of zero degree, the positive azimuth angle was the most economical. The results also showed that the slope of 30 degree and the angle of azimuth equal to zero was appropriate, for which the price per kWh of generated electricity was calculated to be $0.09. For the use of solar cells in the vertical wall of the building, the southwest direction was the most suitable and based on the results, it was suggested that the western wall of the building should be in the form of “inclined PVs with windows”. The authors of this paper hope that the results of the present work can be used by architects and energy decision-makers as a guide in developing the BIPV use in Iran.
Renewable Energy Resources and Technologies
Nima Amani; Abdul Amir Reza Soroush
Abstract
One of the main reasons of environmental pollution is energy consumption in buildings. Today, the use of renewable energy sources is increasing dramatically. Among these sources, solar energy has favorable costs for various applications. This study examined a commercial building in a hot and humid climate. ...
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One of the main reasons of environmental pollution is energy consumption in buildings. Today, the use of renewable energy sources is increasing dramatically. Among these sources, solar energy has favorable costs for various applications. This study examined a commercial building in a hot and humid climate. The findings showed that choosing the optimal angle of solar panels with the goal of optimized energy consumption would yield reduced costs and less environmental pollutants with the least cost and maximum energy absorption. In this study, to calculate the energy requirements of the building, DesignBuilder software was used. To study the solar angles and estimate the energy produced by the solar panels, Polysun software was used after simulating the building energy. Energy simulation results showed that the whole building energy consumption was 26604 kWh/year. Finally, the evaluation results of solar panels showed that the energy produced by photovoltaic modules at an optimal angle of 31° would be equal to 26978 kWh/year, which is more than the energy required by the building. This system can prevent 14471 kg of carbon dioxide emissions annually. Sustainable energy criteria showed that for the studied building, photovoltaic modules could be used in energy production to reach a zero-energy system connected to the grid with an annual energy balance.
Renewable Energy Resources and Technologies
Aychar Khajavipour; Mohammad Reza Shahraki; Faranak Hosseinzadeh Saljooghi
Abstract
The energy of processes is mainly supplied by fossil fuels. Short life of fossil energy sources and increasing environmental pollution caused by fossil fuels and increasing demand have made researchers introduce new solutions for supply of energy. Energy production in a photovoltaic solar power plant ...
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The energy of processes is mainly supplied by fossil fuels. Short life of fossil energy sources and increasing environmental pollution caused by fossil fuels and increasing demand have made researchers introduce new solutions for supply of energy. Energy production in a photovoltaic solar power plant is cost-effective due to being clean and renewable. The power generation of these plants is affected by their site due to climate conditions, effective radiation periods, and the rate of solar radiation absorption. Therefore, finding the optimal location to establish a solar power plant is important. Identifying effective location criteria and the importance of these criteria is effective in choosing the optimal location.In this research, in the first phase, the effective criteria in locating a photovoltaic solar power plant were investigated based on the Delphi method. Then, in the second phase, based on the criteria identified in the first phase, fuzzy hierarchy method was used to compare the criteria with each other and determine the importance of each of them. The results of the study showed that the rate of solar radiation and average temperature were the most important criteria in locating photovoltaic solar power plant. Moreover, the criteria of slope, distance to main roads, distance to power lines, and land use were of highest importance in locating a photovoltaic solar power plant.
Renewable Energy Resources and Technologies
Somayeh Naserpour; Hasan Zolfaghari; Parviz Zeaiean Firouzabadi
Abstract
One of the most important characteristics of site selection for solar energy system installations and optimum solar energy harvesting in the hilly or mountainous terrains is knowledge about the amount and duration of solar radiation within such topographic terrains. Solar radiation data are not readily ...
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One of the most important characteristics of site selection for solar energy system installations and optimum solar energy harvesting in the hilly or mountainous terrains is knowledge about the amount and duration of solar radiation within such topographic terrains. Solar radiation data are not readily available for most mountain terrains because of their rugged topography. For these areas, solar radiation data can be obtained through alternative methods such as the Hemispherical Viewshed Algorithm in which spatial and temporal variations of radiation are calculated in terms of elevation, slope, and terrain. In this study, this algorithm was used to estimate and model solar radiation in the Paraw Mountain in Kermanshah. The inputs for this method were ASTER Digital Elevation Model (DEM) with a spatial resolution of 30 m and meteorological parameters that affect solar radiation. The slope and aspect maps were created from ASTER DEM and layers for monthly direct, diffuse, global, and radiation periods were generated for the year 2016. The results showed that in the Paraw Mountain, the amount of solar radiation received was dependent on the slope orientation, as the north and northeast-facing slopes received the lowest and the south and southwest-facing slopes and the flat areas received the highest direct and global radiation (i.e., in terms of this factor, these landscapes can be recommended as the best site for solar energy system installations and optimum solar energy harvesting). The sum annual radiation period varies from 382.67 to 4310.9 hours, the total radiation received annually varies between 1005.56 and 7467.3 MJ/m2, and the sum monthly solar radiation is the highest in July (181.49-842.26 MJ/m2) and lowest in December (25.42-319.90 MJ/m2). Statistical error comparisons between station-based measurements and model-based estimates were performed via R2, measures. As a result, this model was recommended for solar radiation estimation with acceptable accuracy, especially in high areas with rugged topography where solar radiation data are not readily available.
Renewable Energy Resources and Technologies
Mohammad Reza Shekari; Seyed Mohammad Sadeghzadeh; Mahdi Golriz
Abstract
In recent decade, Perovskite Solar Cells (PSCs) have received considerable attention compared to other photovoltaic technologies. Despite the improvement of Power Conversion Efficiency (PCE) of PSCs, the chemical instability problem is still a matter of challenge. In this study, we have fabricated two ...
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In recent decade, Perovskite Solar Cells (PSCs) have received considerable attention compared to other photovoltaic technologies. Despite the improvement of Power Conversion Efficiency (PCE) of PSCs, the chemical instability problem is still a matter of challenge. In this study, we have fabricated two kinds of PSCs based on gold and carbon electrodes with the optimal PCE of about 15 % and 10.2 %, respectively. We prepared a novel carbon electrode using carbon black nanopowder and natural graphite flaky powder for Hole Transport Material (HTM) free carbon-based PSC (C-PSC). Current density-voltage characteristics over time were measured to compare the stability of devices. Scanning Electron Microscope (SEM) and Energy-dispersive X-ray Spectroscopy (EDS) analyses were carried out to study applied materials, layer, and surface structures of the cells. The crystal structure of perovskite and its association with the stability of PSCs were analyzed using an obtained X-ray diffraction (XRD) pattern. As a result, the constructed HTM-free C-PSC demonstrated high stability against air, retaining up to 90 % of its optimal efficiency after 2000 h in the dark under ambient conditions (relative humidity of (50 ± 5); average room temperature of 25 °C) in comparison to constructed gold-based PSCs (Gold-PSC) which are not stable at times. The experimental results show that novel low-cost and low-temperature carbon electrode could represent a wider prospect of reaching better stability for PSCs in the future.
Renewable Energy Resources and Technologies
Seyed Ali Akbar Fallahzadeh; Navid Reza Abjadi; Abbas Kargar; Frede Blaabjerg
Abstract
This study investigates a new double-stage single-phase Grid-Connected (GC) Photo-Voltaic (PV) system. This PV system includes a DC-DC Positive Output Super Lift Luo Converter (POSLLC) and a single-phase inverter connected to a grid through an RL filter. Due to its advantages, the POSLLC was used between ...
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This study investigates a new double-stage single-phase Grid-Connected (GC) Photo-Voltaic (PV) system. This PV system includes a DC-DC Positive Output Super Lift Luo Converter (POSLLC) and a single-phase inverter connected to a grid through an RL filter. Due to its advantages, the POSLLC was used between PV panel and inverter instead of the conventional boost converter. The state space equations of the system were solved. By using two Sliding Mode Controls (SMCs), PV panel voltage and POSLLC inductor current were controlled and the designed controls were compared. Two of these SMCs included a simple Sign Function Control (SFC) and a conventional SMC. To control the power injected into the grid with a unity power factor, an SMC was used. Perturb and Observe (P&O) method was employed to reach maximum power of the PV panel. The Maximum Power Point Tracking (MPPT) control generated the voltage reference of the PV panel. Similar controls were used for the boost converter instead of POSLLC. The obtained results were compared.
Renewable Energy Resources and Technologies
Ramasamy Dhivagar; Murugesan Mohanraj
Abstract
In this experimental work, the energy efficiency and performance parameters of a coarse aggregate-assisted single-slope solar still were analyzed using Taguchi analysis. The preheated inlet saline water was sent to the solar still using thermal energy accumulated in coarse aggregate to enhance its productivity ...
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In this experimental work, the energy efficiency and performance parameters of a coarse aggregate-assisted single-slope solar still were analyzed using Taguchi analysis. The preheated inlet saline water was sent to the solar still using thermal energy accumulated in coarse aggregate to enhance its productivity and energy efficiency. The daily distillate of the proposed model was observed to be about 4.21 kg/m2 with the improved efficiency of around 32 %. Furthermore, the parameters that influenced the performance of the solar stills and their levels were identified using Taguchi analysis. The Signal to Noise (S/N) ratios of the coarse aggregate temperature, saline water temperature, glass temperature and energy efficiency were observed to be about 45.4 °C, 41.4 °C, 36.7 °C and 20.07 %, respectively. The results revealed that, the percentage difference between predicted and experimental values was observed to be about 1.6 %, 0.6 %, 1.5 % and 3.3 %, respectively. The optimization method confirmed that there was good agreement between the predicted and experimental values.
Renewable Energy Resources and Technologies
Muhamad Mustafa Mundu; Stephen Ndubuisi Nnamchi; Onyinyechi Adanma Nnamchi
Abstract
The present study is concerned with the development, estimation and validation of sunshine hours models (SHM) in Uganda. The SHM is based on geographical (latitude) and climatological (clearness index) indices. The meteosat data (1984-2018) acquired from the National Aeronautics and Space Administration ...
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The present study is concerned with the development, estimation and validation of sunshine hours models (SHM) in Uganda. The SHM is based on geographical (latitude) and climatological (clearness index) indices. The meteosat data (1984-2018) acquired from the National Aeronautics and Space Administration were used to compute the coefficients of the models which, yielded a coefficient of determination close to unity, signifying a good association between the sunshine hours (SH) and the associated indices. The models become distributed by introducing a longitudinal function of clearness index into the primary SHM developed. Moreover, the models were subjected to statistical validation using; mean absolute relative error (MARE), root mean square error (RMSE) and mean absolute percentage difference (APD). Consequently, the primary SHM showed strong agreement with the measured SH data in the three regions with the exception of the northern region with flawed on-station data. Also, validation of the models by; {MARE, RMSE, APD} for Eastern, Central and Western regions, yielding the following results; {0.0788,0.5441,7.8778},{0.0390,0.1453,3.9013} and {0.0124,0.0528,1.2436}, respectively. The following maximum SH; 11.16, 7.87, 9.52, 8.86 and 6.06 h were recorded for Non-regional, Northern, Eastern, Central and Western regions, respectively. Further, comparative validation with redeveloped global SHM showed that the present model stands in all the regions, whereas the global models validated only in the Eastern region. This is attributed to the synergy of geographical and climatological indices against the global models only based on climatological index. The model results show the order of regional SH distribution; eastern>northern>central>western region. These results could be employed in solar power, exploitation and agrometeorology development. This study further recommends for adoption of the present model to non-equatorial regions upon redevelopment as a meaningful extension of this work.
Renewable Energy Resources and Technologies
Narges Barzanooni; Hamid Reza Haghgou
Abstract
In this paper, on the basis of Green comprehensive Plan at Hakim Sabzevari University of Sabzevar, Iran, using of active solar systems at dining hall has been evaluated. On the basis of solar measured data and some solar models and relations, solar energy on the various surfaces and tilts are ...
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In this paper, on the basis of Green comprehensive Plan at Hakim Sabzevari University of Sabzevar, Iran, using of active solar systems at dining hall has been evaluated. On the basis of solar measured data and some solar models and relations, solar energy on the various surfaces and tilts are evaluated. Then electricity and thermal energy consumption are measured and new efficient lighting systems are introduced. Then photovoltaic/thermal panels and one ended evacuated tube solar collector for façade and rooftop installation are chosen. Results shows that 36683 Nm 3 /year natural gas and 87.6 tone/year pollutant are reduced. Payback time of the system based on internal energy carrier and export electricity price are 21.3 and 3.9 years respectively.
Renewable Energy Resources and Technologies
Hadi Farzan
Abstract
The present study investigates the effectiveness of thermostat control strategy in cooling energy consumption in residential buildings. To evaluate the energy consumption, two scenarios including a residential zone with and without the thermostat control system are assumed. The TRNSYS software provides ...
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The present study investigates the effectiveness of thermostat control strategy in cooling energy consumption in residential buildings. To evaluate the energy consumption, two scenarios including a residential zone with and without the thermostat control system are assumed. The TRNSYS software provides an efficient numerical tool to model and evaluate a cooling system. Furthermore, since solar-powered cooling systems for residential air-conditioning are receiving growing and significant interest, a hot-water fired absorption chiller coupled with evacuated tube collectors is considered as the cooling system. The results reveal that the cooling systems consume a large amount of energy in hot climate zones without employing the thermostatic control. Therefore, cooling energy has great potential for a significant saving in hot climates. It is illustrated that the thermostat strategy has an obvious impact on such energy saving. In the current study, employing the thermostat in 90m2 residential building results in saving energy by up to 36%.
