Photovoltaic Systems
Mohammed Zaid Khan; Seema Agrawal
Abstract
This paper considers the context of renewable energy generation for a photo voltaic solar generating system with a non-linear load using one cycle controller with a motor across terminals. The paper finds a comparative study of the pulse width modulator with one cycle controller, which analyses both ...
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This paper considers the context of renewable energy generation for a photo voltaic solar generating system with a non-linear load using one cycle controller with a motor across terminals. The paper finds a comparative study of the pulse width modulator with one cycle controller, which analyses both concepts using power sim software. The main challenge is to reject power supply disturbance. The frequency switch controls the single constant cycle and regulates direct current supply but with transients. As in the case of pulse width modulation, transients appear. In comparison, the one-cycle controlling technique rejects power supply disturbance as the constant voltage maximum power point tracker returns a reference speed value with the speed sensor, so one switching cycle is combined with a dual compensator to reject power supply disturbance as photo voltaic solar generation resolves the supply disturbance in a closed-loop scheme using one cycle modulator. So, in the case of the pulse width modulation technique, the ideal efficiency using the pulse width modulation controller varies from 70.45 % to 75 %; in the case of the novel one-cycle control modulator's excellent efficiency varies from 95.17 % to 99.49 %. Since switching converters efficiently control the photo voltaic energy generation system using one cycle control modulator rather than a pulse width modulator, apart from the swift transient response, one-cycle control modulator imparts economically efficient reference tracking and robustness to the system. The outcome of the one-cycle controller and pulse width modulated controller validates the analysis of variance (ANOVA).
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.
M. Mohammadpour; Seyed M. M. Modarres-Gheisari; P. Safarpour; R. Gavagsaz-Ghoachani; M. Zandi
Abstract
Large amplitude inter-well oscillations in bi-stable energy harvesters made them a proper energy harvesting choice due to high energy generation. However, the co-existence of the chaotic attractor in these harvesters could essentially decrease their efficiency. In this paper, an algorithm for detecting ...
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Large amplitude inter-well oscillations in bi-stable energy harvesters made them a proper energy harvesting choice due to high energy generation. However, the co-existence of the chaotic attractor in these harvesters could essentially decrease their efficiency. In this paper, an algorithm for detecting chaos in bi-stable energy harvesters based on a data-gathering algorithm and estimating the largest Lyapunov exponent is investigated. First, a simple model of axially loaded non-linear energy harvesters is derived. This model is derived using the Euler-Bernoulli beam theory and the Assumed Mode method considering the Von-Karman non-linear strain-displacement equation. The harvester's numerical simulation results are used to test the algorithm's efficiency and accuracy in identifying chaotic response. The results showed the algorithm's success in detecting chaos in such systems with minimum possible calculation cost. The effect of noise on the algorithm's performance has been investigated, and the results showed the excellent robustness of the algorithm to noise. It can diagnose the harvester's chaotic or harmonic behavior with noise-contaminated data, with 10 percent noise density. The comparison between this algorithm and Wolf's method showed relatively less computation time, up to 80 percent, to detect chaos with reasonable accuracy.
Energy Policy
Z. Molamohamadi; M.R. Talaei
Abstract
This paper aims to analyze and identify the most appropriate strategies to deploy solar energy in Iran. For this purpose, in a comprehensive framework of strategy development, the internal and external factors of general and specific environment were determined. Then, four different strategies, including ...
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This paper aims to analyze and identify the most appropriate strategies to deploy solar energy in Iran. For this purpose, in a comprehensive framework of strategy development, the internal and external factors of general and specific environment were determined. Then, four different strategies, including aggressive (strong expansion and development), conservative (maintaining, internal protection), competitive (maintaining, external protection), and defensive strategies (withdrawal, reduction of costs, ceasing on investment, joining another corporation), were considered using internal-external and SWOT (Strengths, Weaknesses, Opportunities, and Threats) matrices. According to the numerical results of the internal and external factor evaluations, which are 2.74 and 3.06 respectively, the aggressive strategies would be acceptable for Iran. However, since the location of these values in the internal-external matrix is close to the conservative cell, the effective strategy for the present condition of our country is a combination of aggressive and conservative strategies.
Photovoltaic Systems
Faridul Islam; Md. Mominul Islam
Abstract
Sustainable Development Goal 13 is an activity committed with the intention of stabilizing greenhouse gas (GHG) levels in the environment to stop potentially harmful human meddling with the climate system. GHG are released into the environment from various non-renewable energy sources of power generation ...
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Sustainable Development Goal 13 is an activity committed with the intention of stabilizing greenhouse gas (GHG) levels in the environment to stop potentially harmful human meddling with the climate system. GHG are released into the environment from various non-renewable energy sources of power generation and many industries that cause extensive damage to the environment. Some countries have begun to implement various pollution prevention strategies, such as power generation from renewable energy sources, which emit no greenhouse gases (GHG) or CO2. This study focuses on an analysis of GHG emission reduction along with the financial feasibility of a grid-connected 100MW PV solar system. This study uses RETScreen software to evaluate the GHG emissions reduction analysis as well as a financial analysis of the system. The annual electricity supplied to the local grid of the proposed PV power plant is 137,481MWh. The cost of reducing CO2 emissions has a positive impact on the overall cumulative cash flow of the proposed system.
Photovoltaic Systems
Christopher T Warburg; Tatiana Pogrebnaya; Thomas Kivevele
Abstract
This study delves into the ongoing discourse surrounding the optimal tilt angles for solar panels to maximize solar PV power generation. Focused on seven equatorial regions in Tanzania; Dodoma, Dar es Salaam, Kilimanjaro, Kigoma, Iringa, Mtwara, and Mwanza. Multiple mathematical models are employed to ...
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This study delves into the ongoing discourse surrounding the optimal tilt angles for solar panels to maximize solar PV power generation. Focused on seven equatorial regions in Tanzania; Dodoma, Dar es Salaam, Kilimanjaro, Kigoma, Iringa, Mtwara, and Mwanza. Multiple mathematical models are employed to ascertain the most efficient panel tilts. Leveraging solar radiation data spanning from 2000 to 2017, we developed an algorithm specifically tailored for computing suitable tilt angles in the southern hemisphere. Our investigation reveals compelling insights into the variation of optimal panel tilts throughout the year. Notably, the monthly optimal tilt angles fluctuate significantly across the regions. June emerges as the month with the highest recorded monthly optimal tilt angle, ranging from 45 degrees in Mtwara to 31 degrees in Kilimanjaro. Conversely, December showcases the lowest tilt angles, spanning from -30 degrees in Mwanza to -26 degrees in both Kigoma and Iringa. Quarterly angles exhibit peaks during the second quarter of the year, reaching 39 degrees in Mtwara and 27 degrees in Kilimanjaro, while experiencing declines in the fourth quarter, plunging to levels between -19 and -24 degrees. Additionally, our study calculates annual optimal tilt angles, revealing a range from 2 degrees in Kilimanjaro to 11 degrees in Mtwara. Crucially, the deployment of monthly optimally tilted solar PV panels demonstrates a noteworthy enhancement, yielding a 6-11% gain in solar radiation compared to horizontally mounted panels. Our study advocates for the adoption of dynamic tilt adjustment strategies of periodic angle alterations to maximize solar PV power generation.
Electricity Generation by Green Energy Sources
Sh. Momen; J. Nikoukar; M. Gandomkar
Abstract
Global warming and prices of energy carriers within political conflicts between different nations, are some of the problems for traditional energy production and economic dispatch. In traditional generation systems, about 25 percentage of energy is wasted, and the presence of Distributed Energy Resources ...
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Global warming and prices of energy carriers within political conflicts between different nations, are some of the problems for traditional energy production and economic dispatch. In traditional generation systems, about 25 percentage of energy is wasted, and the presence of Distributed Energy Resources (DERs) such as Photovoltaic, Wind Turbine and wind farms, Fuel Cell, and the Combined Heat and Power can reduce fuel consumption, pollution, transmission losses, and increase the microgrid productivity. In this paper, a complete energy management framework in a microgrid is proposed by considering the load distribution constraints using Improved Shuffled Frog Leaping Algorithm (ISFLA) algorithm, in which it determines the exact share of energy production or consumption for different units. The proposed scheme is used to select the best arrangement of DERs in the power grid, which the output of which is to determine the number and optimal location of DERs in the several bus-bars of the grid. Then, the Independent System Operator (ISO) determines the quantity of energy exchange and consumption by considering the load distribution constraints. Boilers and CHPs have also been used to maintain the balance between the production of thermal power by energy sources and thermal demands. In addition, the Demand Response Program has been used with the aim of smoothing the load curve and reducing the operating costs. Finally, the proposed method is implemented and simulated on the IEEE 69 and 118 bus systems using MATLAB, which comparing the output results with existing algorithms, shows the superiority of the proposed method.
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.
S.Ollah Mohammadi-Aylar; M. Almassi; H. Bakhoda
Abstract
Due to the needs of modern societies to provide their energy fully or partially from the renewable energy sources and its necessity as a main principle of sustainable development, its necessary to assess and evaluate renewable energy and its integrating for utilizing a part of consumed energy for societies ...
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Due to the needs of modern societies to provide their energy fully or partially from the renewable energy sources and its necessity as a main principle of sustainable development, its necessary to assess and evaluate renewable energy and its integrating for utilizing a part of consumed energy for societies from cheap energy resource and solving the ecological and social problems. Despite of great potentials of Ardabil province in agriculture, water streams, climatic precipitation and climatic conditions, the necessity of appropriate investments in order to better exploitation form these capabilities (renewable energy) increases. The goal of this research is to potentiometry for the exploitation of renewable energies (solar, wind, biomass and bio-energy, water) based on farming, improvement of policy making for developing renewable energies, developing atlas of renewable energies based on farming and improving policy making of developing renewable energies in Ardabil province. According to the results of this study, the most talented town of Ardabil province in terms of renewable energy is Meshgin shahr town. Solar energy 3/449 kW h/m2/y, hydropower 270/34 Gw h/y and geothermal 76/11kw h/y ranked the first among all the cities of Ardabil province. And the lowest was Sarein city.
Solar Thermal Engineering
Mohammed Gwani; Abdullahi Bello Umar; Abubakar Gado Abubakar
Abstract
Traditional cooking methods using fuel woods can pose very serious challenges of local and regional air pollution and land degradation. These methods are inefficient, unsustainable and have serious implications to the environment. To overcome these challenges, a novel four reflectors solar baking oven ...
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Traditional cooking methods using fuel woods can pose very serious challenges of local and regional air pollution and land degradation. These methods are inefficient, unsustainable and have serious implications to the environment. To overcome these challenges, a novel four reflectors solar baking oven has been designed and tested for application in rural areas. The solar baking oven consists of four reflectors made from plane mirrors which reflect the Sun’s rays to the absorber plate placed at the baking chamber. The four reflectors intensify the incoming solar radiation into the baking chamber and increase the thermal properties and efficiency of the oven thereby resulting in shorter cooking time. The result obtained from the study showed that the oven can attain high temperature values. The temperature values are higher when the oven is loaded compared to when the oven is unloaded. When the oven is unloaded, the highest temperature attained by the four reflector solar baking oven is 128.6oC at 13:00 pm, as compared to 133oC at 13:00 pm, when the oven is loaded.
Electricity Generation by Green Energy Sources
Mowffaq Oreijah; Hosam Faqeha; Moaz Al-Lehaibi; Kamel Guedri; Sina Hassanlue
Abstract
Distributed electricity generation has been a long-standing focus for researchers and policymakers. With the global rise in electricity demand, various generation methods such as solar, wind, fuel cells, and internal combustion engines—are being implemented, each with distinct advantages and drawbacks. ...
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Distributed electricity generation has been a long-standing focus for researchers and policymakers. With the global rise in electricity demand, various generation methods such as solar, wind, fuel cells, and internal combustion engines—are being implemented, each with distinct advantages and drawbacks. Micro gas turbines have emerged as a viable candidate for a reliable, cost-effective, and accessible energy production system. To enhance overall system efficiency, the heat produced from fuel combustion in these turbines can also be used to generate hot water. This study investigates micro gas turbines fueled by biogas, analyzing the effects of several critical parameters: Turbine Inlet Temperature (TIT), Compressor Pressure Ratio (CPR), and recuperator effectiveness within the cycle. The thermodynamic modeling uses the thermally perfect gas model and was conducted in EES (Engineering Equation Solver), with a selected commercial gas microturbine used for validation. Variable fluid thermodynamic properties are accounted for based on temperature, providing accuracy under diverse operational scenarios. It is found that to achieve the maximum overall efficiency, there is an optimal value for the CPR while it increases with increment in the TIT and recuperator effectiveness.
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.
Ravinder Kumar; Anand K. Bewoor; R. Alayi
Abstract
India’s rapid economic growth and change in lifestyle have increased the level of municipal solid waste (MSW) generation in the country. Metropolitan cities in India are contributing a major portion (in lakhs metric tons per day) of MSW. It is only due to the lack of availability of poor infrastructure ...
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India’s rapid economic growth and change in lifestyle have increased the level of municipal solid waste (MSW) generation in the country. Metropolitan cities in India are contributing a major portion (in lakhs metric tons per day) of MSW. It is only due to the lack of availability of poor infrastructure to handle MSW in the country. Also, the people ignorance towards to handle these waste is also a big challenge to handle this problem. The implementations of low-cost and user-friendly methods are the primary need to handle this kind of situation. It can be easily predicted that Kitchen waste (KW) is contributing a major portion in MSW and its ignorance towards disposing off is increasing environmental pollution day-by-day. It is the motivation of the present study and a comprehensive review of KW generation in India has been done. A study based on prefeasibility to handle KW is also done and based on that a feasible solution is provided to handle KW on waste to energy for sustainable new business investment opportunities in the present work. The proposed plan will not only reduce the level of MSW in the country but will also create a lot of opportunity for employment in the country for a future generation. The present work concludes that installation of this kind of pilot project in metropolitan cities is the present need for the development of the recycling industry sector using KW as a raw material in India.
Wind Energy
M. Ahmadi; S.A.A. Mirjalily; Seyed A. A. Oloomi
Abstract
This study applies an appropriate turbulence model to simulate the wind distribution in a 3D urban area around a tall building as a bluff body which is one of the most important research topics due to the increasing concerns about human health risks due to air pollution in recent decades. Hybrid RANS/LES ...
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This study applies an appropriate turbulence model to simulate the wind distribution in a 3D urban area around a tall building as a bluff body which is one of the most important research topics due to the increasing concerns about human health risks due to air pollution in recent decades. Hybrid RANS/LES approach, was used to reduce computation time while maintaining computational accuracy. On the other hand, since no homogeneous direction exists in the flow in the Hybrid (RANS-LES) approach, the LES and Smagorinsky Sub Grid-Scale (SGS) approach are implemented with the standard k-ε turbulence model as RANS. To obtain more accurate results, the second-order Van Leer Method (VLM) was employed in advection terms. The sensitivity study of the input parameters shows that the intensity of the input turbulence has a significant effect on the surface pressure fluctuations. The results of velocity and pressure distribution showed a very close agreement to wind tunnel experimental data. Finally, the effects of the inflow characteristics on the peak pressure on the lateral sides is also studied. As the results, fluctuation pressure distribution was strongly dependent on the turbulence of the flow.
Solar Thermal Engineering
Seyed Younes Afshoon; Rouzbeh Shafaghat; Mofid Gorji Bandpy
Abstract
This paper investigates the melting behavior of phase-change material (PCM) in an evacuated tube solar collector. The outer tube was made of borosilicate glass with a diameter of 60 mm, and the inner tube was made of copper with a diameter of 10 mm and length of 1500 mm. The heat transfer problem in ...
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This paper investigates the melting behavior of phase-change material (PCM) in an evacuated tube solar collector. The outer tube was made of borosilicate glass with a diameter of 60 mm, and the inner tube was made of copper with a diameter of 10 mm and length of 1500 mm. The heat transfer problem in heat pipe was investigated in four cases: finless, full fin, half fin, and third fin. The fins were cut from a 35 mm diameter copper tube and installed concentrically with the outer tube. The inner space between the absorber tube and the heat pipe was filled with stearic acid as the PCM. The numerical simulation was conducted using the Ansys Fluent 2022 for the laminar incompressible Newtonian fluid flow in the transient state via the enthalpy-porosity model. The initial temperature of PCM was 27°C, and liquid fraction was zero at the beginning of the simulation. After validating the numerical results with experimental ones, the collector performance was evaluated by considering the four temperatures of 68, 72, 76, and 80°C for the fin and heat pipe at three different times t = 22, 55, and 110 s. The results showed that by increasing the fin area in three cases of third fin, half fin, and full fin, the melting and storage time of PCM were reduced by 6%, 44%, and 87%, respectively. Also, as the Estefan number increased from 0.007 to 0.05, 0.09, and 0.13, the process of PCM melting decreased by 75%, 85%, and 92%, respectively.
Photovoltaic Systems
Bandar Mohammad Fadhl; Basim Mohammed Makhdoum; Kamel Guedri
Abstract
Renewable energy systems have received special attention in recent decades, mainly due to the environmental problems of using fossil fuels, fluctuation in the price of these fuels, limitations in their resources, and considerable demand for energy. Solar photovoltaic (PV) modules are among the most attractive ...
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Renewable energy systems have received special attention in recent decades, mainly due to the environmental problems of using fossil fuels, fluctuation in the price of these fuels, limitations in their resources, and considerable demand for energy. Solar photovoltaic (PV) modules are among the most attractive options for power production using solar energy. A variety of factors, including the material, operating conditions, and temperature, influence PV efficiency. Elevation in the cell temperature causes degradation in efficiency and consequently the production of electricity at a constant solar radiation intensity and operating conditions. In this regard, employment of thermal management systems is considered to avoid temperature increments. Hybrid nanofluids, due to their significant thermophysical properties, are attractive options for thermal management of PV cells. This article reviews and presents studies on the thermal management of PV cells. We conclude that different factors such as the type of nanomaterial, cooling configuration, and operating conditions influence the effectiveness of hybrid nanofluids in thermal management of PV cells. Furthermore, reports suggest that the use of hybrid nanofluids, depending on the nanomaterials, may be more effective than single nanofluids in reducing the temperature of PV modules. Applying hybrid nanofluids instead of pure fluids would result in higher energy and exergy efficiencies. Aside from technical benefits, utilization of hybrid nanofluids in PV cooling could be beneficial in terms of economy. For instance, using hybrid nanofluids for module cooling can reduce the payback period of the systems.
S. Jafarian; E. Sarkardehee; D. Monsefi Parapari; M.R. Mojahedi
Abstract
In urban open spaces, especially in large cities with warm climates, users are experiencing high thermal loads, which causes thermal discomfort. Thermal comfort in open spaces can be improved; by shading. The problem is shading and protecting open spaces from stresses caused by overheating of the earth's ...
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In urban open spaces, especially in large cities with warm climates, users are experiencing high thermal loads, which causes thermal discomfort. Thermal comfort in open spaces can be improved; by shading. The problem is shading and protecting open spaces from stresses caused by overheating of the earth's surface and environment. The importance of shade and reducing radiation in achieving thermal comfort in open urban spaces is to increase human presence, create climate change, increase comfort conditions. Recognizing factors that create shadows, such as canopies and their characteristics, can create a favorable space to enjoy the capabilities of outdoor space. New membranes have many characteristics of nomadic tents, and, due to creating shade and natural ventilation, are very suitable for areas with hot climates. Introducing an optimal model and dimensions of a lightweight membrane canopy can create outdoor thermal comfort and increase the efficiency of outdoor spaces. In this paper, library, field, and simulation studies have been used. According to field studies, the presence of membrane canopy can cause temperature differences up to 7.8 C. The simulation results with Ansys, ENVI-met, and Ladybug showed that the membrane canopy cools the space below and prevents overheating. Between four canopy models, the saddle canopy is suitable with a 40.63% impact on the environment and creates cooler space under the canopy. Therefore, a lightweight saddle membrane canopy with dimensions of 5*5 m^2 and a useful height of 3 meters is introduced as a suitable model of membrane canopy for the hot climate of Semnan.
Solar Thermal Engineering
A.R. Shateri; I. Pishkar; Sh. Mohammad Beigi
Abstract
Trombe walls and solar chimneys have been widely used by the construction industry for many years to heat buildings. In this study, the heat conductance of a Trombe wall was simulated and studied. The equations related to energy and momentum were solved numerically by use of the technique of control ...
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Trombe walls and solar chimneys have been widely used by the construction industry for many years to heat buildings. In this study, the heat conductance of a Trombe wall was simulated and studied. The equations related to energy and momentum were solved numerically by use of the technique of control volume. The equations were solved simultaneously using the Simple algorithm. At first, a base case was defined and simulated. A sensitivity analysis study was then performed to investigate the parameters affecting the performance of the wall. Based on the results, an optimized geometry was suggested which maximized the performance of the Trombe wall. In addition, the effect of the presence of the fins on the surface of the absorber wall was studied. In order to obtain the best geometry, the fins were assumed to have different shapes but a constant area. The results showed that the Trombe wall with rectangular fins demonstrated the best performance compared to the other fin geometries studied in this paper. The presence of rectangular fins can increase the room temperature by 1.24% compared to other fin geometries.
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.
Photovoltaic Systems
Arash Mahdavi; Mousa Farhadi; Mofid Gorji Bandpy; Amirhoushang Mahmoudi
Abstract
Regulating the operating temperature of photovoltaic (PV) systems is essential for their longevity. An efficient passive cooling method involves the incorporation of Phase Change Materials (PCMs). In this study, a novel nonlinear analytical solution is employed to investigate the melting and solidification ...
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Regulating the operating temperature of photovoltaic (PV) systems is essential for their longevity. An efficient passive cooling method involves the incorporation of Phase Change Materials (PCMs). In this study, a novel nonlinear analytical solution is employed to investigate the melting and solidification processes within the PV-PCM system, which operates continuously for 24 hours each day. The analytical approach significantly reduces computational time to a few seconds compared to over three months required by CFD techniques. The transformation of the partial differential energy equation into a nonlinear ordinary differential energy equation facilitates precise observation of both melting and solidification processes of the PCM material. The analytical approach is further applied to assess the performance of the PV-PCM system during two typical summer days in 2020 and 2021. Additionally, the impact of PCM thickness on the PV-PCM system is examined as a variable input. Results indicate that increasing PCM thickness from 1 cm to 5 cm reduces the peak temperature of the PV module by approximately 7 . This temporal shift is significant, enabling the PV module to operate at cooler temperatures during peak solar intensity, resulting in higher power output. The analytical solution proves instrumental in determining the optimal PCM thickness for a PV-PCM system in any location within seconds. Findings reveal that a 5 cm PCM thickness leads to a 13% decrease in maximum temperature and a 3.4% increase in minimum electrical efficiency. The integration of thermal energy storage enhances the overall efficiency and performance of the PV system.
Systems with Low Energy Consumption
Ahmadreza Keshtkar Ghalati; Mahdieh Ahmadian
Abstract
Light shelves not only create shade but also improve the uniformity of daylight. In addition to saving energy, they can improve the lighting quality of a space. This research aims to position light shelves and deep windows to enhance energy efficiency and daylight illuminance in classrooms in Abadan ...
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Light shelves not only create shade but also improve the uniformity of daylight. In addition to saving energy, they can improve the lighting quality of a space. This research aims to position light shelves and deep windows to enhance energy efficiency and daylight illuminance in classrooms in Abadan (Iran) with hot and dry climates. Rhino/Grasshopper software and Ladybug/Honeybee plugins were used to model and evaluate visual comfort and EUI. By comparing the types of external, internal, and central shelves and in different situations of window depth, the following results were obtained: By combined use of light shelves and deep windows: In central light shelves, energy consumption decreased by 20%, and glare effects were reduced by 53.37%. As a result, installing a window in the depth of the wall did not have much effect on reducing energy consumption, but to some extent, it controlled the intensity of glare. The deep window has reduced energy consumption (13%), and using light shelves has improved energy performance (14 to 20%). Compared to the base model, the combined light shelves reduced UDI by 20% and glare by 53%, while the inside light shelves reduced UDI by 14% and glare by 30%. Therefore, installing light shelves always reduces glare. But if the intention is to save energy, the central and external light shelves in the position of the deep window are very useful.
W. Rahimy; Gh. J. Laame; E. Acikkalp; S. Yerel Kandemir
Abstract
Due to the increasing population growth and energy need, interest in renewable energy sources has increased in recent years. Biogas is one of the sustainable energy resources in the world. In cattle, ovine, and poultry farming, a large amount of fertilizer is produced in Afghanistan. These wastes are ...
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Due to the increasing population growth and energy need, interest in renewable energy sources has increased in recent years. Biogas is one of the sustainable energy resources in the world. In cattle, ovine, and poultry farming, a large amount of fertilizer is produced in Afghanistan. These wastes are a big problem for businesses, and their evaluation is of great importance. One of the ways to utilize wastes is biogas production. In this study, the annual biogas and total annual heat value potential of Afghanistan, depending on the number of animals, were determined. As a result, Afghanistan's biogas potential between 2010 and 2017 is between 1172355870 m3/y and 1282692614 m3/y. It has been determined that the total annual heat value potential is between 29117122340 MJ / y and 26612478246 MJ /y. As a result, it was seen in this study that the widespread use of biogas in Afghanistan is of great importance in terms of both waste disposal and energy production
Systems with Low Energy Consumption
Seyed E. Hoseini; M. Simab; B. Bahmani-Firouzi
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.
Energy Policy
M. Mohamadi Janaki; M. A. Sobhanallahi; A.R. Arshadi Khamseh
Abstract
The trend of the fourth industrial revolution in the field of energy, like other sectors, indicates that the path of production, development and approaches to energy use in the world is changing every day. This change can be seen in the growth of new energy production in developed countries by renewable ...
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The trend of the fourth industrial revolution in the field of energy, like other sectors, indicates that the path of production, development and approaches to energy use in the world is changing every day. This change can be seen in the growth of new energy production in developed countries by renewable energy. Owing to the global energy crisis all around the world and the exhaustible non-renewable energy resources, as well as increasing the pollution and green supply chain due to the indiscriminate use of fossil fuels, the need to use sustainable energy, especially In the industrial sector, which accounts for 40% of energy consumption in our country, has been paid attention to. The present study developed and prioritized green supply chain strategies with uncertainty over time under fuzzy conditions in Mobarakeh Steel Company. First, the internal strengths, weaknesses, opportunities, and threats were identified based on theoretical foundations and experts’ opinion. Then, the green supply chain strategies of Mobarakeh Steel Company were developed using the SWOT method. Fuzzy ANP method was used for weighing the dimensions of sustainability while the TOPSIS and TODIM methods were used for weighing the strategies. The results indicated that among the indicators of sustainability, "social" indicator had the first rank, "environmental" indicator had the second rank, and "economic" indicator had the third rank. In addition, SO strategies had the first rank, ST strategies had the second rank, WO strategies had the third rank, WT strategies had the fourth rank.
H. Alm ElDin Mohamad; E. Medhat; ElSamadony M.; R. Mohamed; M. Muthu
Abstract
Due to traditional energy resources problems, scientists looked for a new concept to face these problems. The Solar chimney is one of the promising concepts in renewable energy technology that needs performance enhancement, the proposed study aims at assessing the remarkable advances in the understanding ...
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Due to traditional energy resources problems, scientists looked for a new concept to face these problems. The Solar chimney is one of the promising concepts in renewable energy technology that needs performance enhancement, the proposed study aims at assessing the remarkable advances in the understanding of solar chimney power plant (SCPP) performance investigation through extensive studies with different focuses on several aspects of SCPP technology. In this scientific review paper solar chimneys based on the historical review, enhancements, working principle, components and effective factors, advantages and disadvantages.