نشریه انرژی های تجدیدپذیر و نو
سال دوازدهم شماره 1 (پیاپی 23، بهار و تابستان 1404)

The present research investigates the thermodynamics of two dual-purpose condensation refrigeration systems, including a system with a flash-chamber and a cascade refrigeration system used in cold storages with the aim of providing two temperature ranges above zero and below zero. The purpose of this research is to investigate the annual energy consumption of dual-purpose refrigeration systems with environmentally friendly refrigerants and also to investigate the parameters affecting the efficiency of these systems. Results show that the best refrigerant in terms of performance in both refrigeration systems is R290. The system with a flash-chamber has a higher efficiency, and its energy consumption is 30% lower in hot and humid areas and almost 20% lower in other climates than the cascade system. Also, it was found that flash-chamber system has more limitations than the cascade system, and many refrigerants cannot be used in it due to pressure limitations. The comparison of these two systems shows that with the assumption that the total load capacity of the cold storage is constant, the energy consumption of both systems increases with the increase of the thermal load of the sub-zero evaporator.

Nowadays, with the increasing consumption of energy, the use of renewable energy has become particularly important. Among the renewable energy resources, solar energy has significant potential due to its advantages like a lower price, stability, etc. One of the simplest and most effective means of collecting solar energy is the flat panel solar collector. In this project, a new model of the solar collector was simulated using Fluent software. The effect of important parameters in the design of the collector such as absorption plate thickness, tube diameter, and the number of tubes are evaluated. The simulation results show that increasing the diameter of the tubes, increasing the number of tubes which means reducing their distance, and increasing the thickness of the absorber plate all improve the efficiency of the flat plate solar collector system. To compare the performance of this type of geometry with the conventional collectors, another type of geometry for the solar collector in which half of the tubes are at the top of the absorber plate is simulated in Fluent software. The results of comparing these two types of geometry show that the geometry of the first type has an energy efficiency of 59.63% in the best simulation model and the geometry of the second type in which half of the tubes are above the absorber plate has an efficiency of 67.79%.

The inability of conventional energy sources to fully meet the ever-increasing energy demand in today's world points to the ever-increasing importance of hybrid power generation systems. Today, the hybrid systems of electricity production, in which part or all of its sources are renewable energy sources, have attracted the attention of many researchers, scientists, and investors. This research proposes an independent multi-source hybrid generation system with optimal design, including photovoltaic panels, wind turbine generators, batteries, and diesel generators. This research aims to minimize the emission of carbon dioxide and the cost, which is expressed in the form of the net present value of the system. The designed hybrid power generation system is further integrated into the distribution system as a distributed generation. This is to optimally improve the distribution system's performance by minimizing the entire distribution system's total losses and voltage deviation. The combined cost and emissions of energy purchased from the grid and energy produced by distributed generation are also reduced. For this purpose, a multi-objective particle swarm optimization algorithm has been developed. The proposed optimization algorithms are implemented using software for an IEEE standard 33-bus distribution system. The location and size of scattered productions and the type and number of each generating source of the hybrid system are considered decision variables.

The main source of human energy supply is fossil fuels, which cause an increase in the earth's temperature and serious environmental damage. A significant part of energy consumption in the world and Iran is related to residential buildings. Consumers of a major part of this energy in residential buildings are cooling and heating systems. Therefore, saving and optimally selecting cooling and heating systems in residential buildings is essential and can help to reduce fossil fuel consumption. In the present study, seven different scenarios, each of which includes an independent or central cooling system and an independent or central heating system, were technically and economically investigated in two high-rise residential buildings in Tehran. The results showed that central heating and cooling systems (such as boiler and chiller with fan coil and air handling unite) perform better than independent systems (such as water cooler, air conditioner, split duct, air washer, zent, package, heater - water heater) in high-rise buildings. Also, with the increase of building units (area), the performance of central systems becomes better and the performance of independent systems becomes weaker.

Global energy demand will increase by 1.8% annually between 2000 and 2030. Carbon dioxide gas increases by 1.2% per year. Lack of energy and air pollution are two big problems of humanity. The use of renewable energy sources with the least environmental pollution is very important. Attention to the low pollution effect of harvesting energy from the wind has led most researchers to research this type of energy. Wind energy is one of the renewable energy sources, the new generation of bladeless wind turbines is based on a flexible structure. This article is an overview of 67 fundamental researches in this new field that are being investigated by researchers, which are based on validity and practical testing. The FSI calculations made in the articles have been filtered, the studies made are mainly to optimize the use of renewable energy of the bladeless turbine and check one or two parameters. The simulated wind turbine model is without blades, almost all parameters effective in energy harvesting in these turbines have been investigated, and an adjustment system has been used to increase the productivity hours of the wind turbine per year.

Electricity generation outside the national electricity network is a method of providing energy in residential, commercial or rural areas. In the new approach, the diesel generator is combined with renewable energy technologies, firstly, the suitable location for the construction of a hybrid power plant in South Khorasan province has been investigated according to 14 indicators and 15 different options using Shannon entropy weighting method and TOPSIS decision making method. The results show that the best weight of the indices using Shannon entropy method is related to the index of distance to the road, distance to the national electricity network and population respectively. Then, among the options, Asadiyeh with a score of 0.8932 and Eshghabad with 0.8853 receives the highest score using the TOPSIS method. By choosing Asadiyeh as the best place to build a hybrid power plant, a power plant consisting of diesel generator, wind turbine, solar panel and battery has been designed to supply the consumption load of a village. The consumption of this village is 213.6 kilowatt hours per day and the peak consumption is 25.45 kilowatts. To supply this load, 9.29 kW solar panels, 2 10 kW wind turbines, 29 kW diesel generators, 18 5 kW batteries and 10.4 kW inverters are needed. The investment cost of the proposed system is 31314 euros and the production cost per kilowatt of energy is 0.0784 euros, the operating cost of this system is 3689 euros and the fuel consumption of the diesel generator during the year is 4654 liters.

The performance and environmental benefits of fuel cells make them a popular choice for distributed generation systems (DGs). Fuel cells are connected to the network using power electronic converters. Power inverters have high frequency harmonics due to PWM switching and its control delays. LCL filters are used to eliminate these harmonics. Network impedance changes affect the resonant frequency of LCL filters and may cause system instability. Active damping methods are used to weaken the resonance of LCL filters. In this paper, a fuel cell system is used to inject power into the grid through a power inverter and LCL filter. Integral-proportional capacitor current feedback is used for LCL filter resonance damping. MATLAB/Simulink simulation results are presented to verify the validity of the proposed method. Integral-proportional capacitor current feedback is used for LCL filter resonance damping. MATLAB/Simulink simulation results are presented to verify the validity of the proposed method.The simulation results show that the proposed method is stable against changes in network impedance and fuel cell parameters, and provides a good performance. The simulation results show that the proposed method is stable against changes in network impedance and fuel cell parameters, and provides a good performance.

High consumption of energy in commercial buildings due to public use at different hours leads to irreparable consequences, including damage to the environment. As an effective building component in radiation control, facade plays an important role in reducing energy consumption. Unfortunately, in recent years, attention to the aesthetic dimension of the building has caused the role of the facade and the use of up-to-date techniques in the field of building technology to be less investigated as an effective energy reducer. The current study, by using a double-shell facade instead of a single-shell facade or a combination of single-shell and two-shell facades in a commercial building in Karaj, investigates the role of using double-skin facades and combined facades in reducing heat and cold loss through walls. The study conducts library and documentary studies to conduct research background, and establishes simulation method using Design Builder software to measure the effectiveness of the mentioned technique in cold and dry climate. The results of the study show that the consumption of gas and electricity in the coldest and hottest months of the year in the combined facade compared to single skin facade is reduced by approximately 20% and 15%, respectively. On the other hand, due to the insignificant reduction of energy in the comparison of two-layer and combined facades, in order to reduce the costs of construction and execution in the building, the combined facade has a better justification in cold and dry climates.

Considering the climate changes, reduction in fossil fuel resources, low energy efficiency, and population growth rate, the transition towards renewable energies is one of the most important goals and challenges facing the world. The aim of the present study is to analyze the trend of scientific publications by Iranians in the field of renewable energies on the Web of Science using scientometric indicators. In this research, the trend of publications, leading authors, active scientific centers, key research topics of Iranians, and collaboration networks of Iranian authors with the authors of other countries in the field of renewable energies were identified and analyzed. The findings showed that during the years 1976-2022, a total of 13,998 documents by 2,617 Iranian authors, receiving 288,603 global citations in the field of renewable energies, were registered on the Web of Science. Iranian authors account for 2.57% of all publications in the field of renewable energies, ranking 13th globally. It was also revealed that there is a significant correlation between the cumulative frequency of annual scientific productions in the field of renewable energies and the years from 1976 to 2022. Based on this, it can be predicted that if the publications of scientific productions on renewable energies continues at the same rate, the cumulative frequency of scientific productions in this field in 2030 will be nearly five times that in 2022.

The increasing production of urban, rural, and industrial wastes and how to manage and bury these wastes is one of the challenges of human societies. Biogas is one of the types of renewable energy that is produced from organic materials known as biomass. In the present study, biogas production from anaerobic digestion of cow manure and residues of wheat, barley, and chickpea crops (with a ratio of 25:75) was investigated on a semi-industrial scale. Then its energy and life cycle indicators were evaluated. The study of energy indicators showed that in producing biogas from each ton of the combination of chickpea, wheat and barley residues with cow manure, the ratio of net energy was 1.649, 1.613, and 1.554, respectively. Also, in this process, the net energy benefit for each ton of the combination of chickpea, wheat, and barley residues with cow manure was equal to 12191.4, 11816.4 and 10956.554 MJ, respectively. In other words, the production of biogas from the combination of pea residues with cow manure had the best results and the combination of barley residues with cow manure had the weakest results. Intermediate environmental indicators and life cycle assessment in biogas production were evaluated in three scenarios of combining wheat, barley and chickpea residues with manure. According to the obtained results, the combination of chickpea residue with cow manure is more environmentally friendly than the other two combinations and is a more suitable scenario from the point of view of life cycle assessment.

Environmental crises due to the ever-increasing energy consumption are undeniable. Moreover, the wide influence of the construction industry, especially educational buildings as one of the biggest energy consumers, the importance of comfort impact on increasing the performance, and academic efficiency of students, and the need to provide solutions for retrofitting and designing effective educational buildings in sync with the operation and design stage, make it necessary to notice the external walls of the buildings. To achieve the optimal pattern in school design and retrofitting, provide comfort, reduce energy consumption, and deal with environmental crises; among other variables, investigating the layering of the outer shell based on environmental indicators is one of this research goals. The following quantitative-analytical research has applied purpose. To advance studies and investigate the independent and simultaneous effect of research variables (type and thickness of thermal insulation and types of building insulation blocks) on reducing energy consumption and CO2 emissions and increasing comfort hours; Despite simulating and validating the results obtained from the Design-Builder software, the comparative evaluation method has been used to compare the results with the current state of the building. The results indicate that the implementation of an air layer or EPS thermal insulation sheet with thickness 5 cm for existing buildings and 4 - 5 cm for new buildings will bring the best performance. Regarding environmental indicators, using insulated External walls combined with clay blocks has better and more economical performance than using insulation blocks such as Leca and Heblex.

One of the most important sources of renewable energy is wind energy. We can harness the kinetic energy of the wind by using wind turbines. One of the fundamental problems with Savonius wind turbines is their low efficiency due to direct wind impact on the returning blade and applying negative torque to it. One new and cost-effective method to increase the efficiency of these turbines is to use a deflector upstream of the flow to prevent wind from hitting the returning blade and producing negative torque. Due to the cylindrical geometry of the deflector, it cannot guide the flow at an arbitrary angle. Additionally, a relatively large vortex region will form downstream of the deflector and near the turbine, which will have undesirable effects on turbine performance. These vortices can be controlled by installing flow splitter blades on the deflector. This study used computational fluid dynamics techniques in a two-dimensional simulation with Ansys Fluent software. Initially, a cylindrical deflector without flow splitter blades was designed and its simulation results were validated with previous experimental research. Then, as an innovation, a splitter blade was installed at a desired angle and directed flow towards the advancing blade of the turbine. The simulation results show that using a deflector with splitter blades at an angle of 5 degrees increases the turbine power coefficient by 23.4% compared to its state without a deflector at a tip speed ratio of 0.6.

Areas with geothermal potential naturally have evidence on the ground surface that is used in geothermal energy exploration projects to initially locate these areas. The purpose of this research is to identify areas with surface geothermal energy potential by combining the surface temperature and energy flow resulting from the Sabal algorithm using the thermal sensor data of Landsat 8 and 9 satellites in Shut-Mako region of West Azarbaijan province located on the northwest of the country. For this purpose, Landsat 8 satellite images on August 14, 2023 and Landsat 9 data on September 7, 2023 were used. Then, using the split window algorithm, the temperature map of the land surface Temperature was estimated. Then, using the Sentinel 3 thermal sensor image, the estimated temperature was Validation using the linear regression analysis model. Next, using the Sebal Algorithm, the amount of net radiation received by the surface, net energy directed to the ground and the amount of solar radiation absorbed by the surface estimated, for minimize the effect of solar radiation on the estimated land surface temperature. By combining the thermal flows estimated from the Sebal algorithm and estimated land surface temperature, the geothermal energy potential areas were identified and determined. The natural hot spring as one of the evidences of geothermal energy, confirmed the pixels obtained in the final map results and showed that there are areas in the study area that have a high potential for geothermal Energy.

In recent years, the environmental crisis caused by the increasing emission of carbon dioxide is expanding. For this reason, the world is turning towards renewable energies at a considerable speed. The renewable energy system has a great potential for decarbonizing the environment; because they do not produce greenhouse gases or pollutants. Renewable energy systems rely on natural resources such as sunlight, wind, water, and geothermal energy to produce energy. These sources include uncertainty and depend on weather, season, and year. To account for these periodicities, renewable energy can be stored using various methods. Then, if needed, it was used in a fixed and controlled manner. Energy storage system technology provides the possibility of absorbing, storing, and releasing energy for later use. Energy storage systems can help balance electricity supply and demand, improve grid stability, reduce carbon emissions, and facilitate the integration of renewable energy sources into the grid. In this research, the types of energy storage systems subsets such as thermal, chemical, electrochemical, mechanical, electrical, and hybrid are classified and then their advantages and disadvantages and operating principles are compared and investigated.

Nowadays by studying about elements of climatic architectures, new systems have been created based on functional analysis on those elements. Wind catcher is one of those functional elements. The new generation of wind catchers can improve comfort zone in interior spaces with low energy consumption. On the other side, the indoor air quality (IAQ) factors are extremely substantial and have significant impact on students’ performance. Therefore, these factors must be monitored, controlled and be brought to the desired level. This study investigates the use of new generation of wind catchers to control natural ventilation and CO2 level in the educational environments of Iran moderate and humid climate. This review research includes a comprehensive literature review and the descriptive-analytical research method has been used to draw conclusions and generalizes the results in the moderate and humid climate of Iran. In order to determine the results, at first, the wind speed required to activate the new generation of wind catchers was collected in comprehensive literature review. The necessary evaluations were made regarding the ability of the new generation of wind catchers to provide the necessary standards in ventilation rate and air carbon dioxide level. The results reveal that according to the average wind speed in the three studied cities, the new generation wind-catcher systems in most of the year, considering a blower fan at the beginning of the path, are able to provide the necessary standards in ventilation rate and carbon dioxide level of the air in educational spaces.

In solar dryers, thermal energy is supplied by the unlimited radiation of the sun, so the drying process is highly dependent on different local weather conditions. Different types of solar dryers have been designed and developed in different parts of the world. Among the categories of solar dryers, the indirect type solar dryer has more advantages. The research strategy of this study was conducted in the form of narrative review by searching for related articles in Google scholar search engine using the keywords heat transfer, heat storage energy, phase change materials, solar energy, solar dryer. According to the results of the study, the use of phase change materials in indirect solar dryers provides the quality of dried product in a shorter period of time, so that the air temperature inside the chamber is 4 to 20 degrees Celsius higher than the ambient temperature even after sunset. Celsius above the ambient temperature. It can also reduce post-harvest losses of agricultural products in rural areas of developing countries. This work helps to understand the drying process, different types of dryers and their performance, and energy management in dryers using nanocomposites of phase change materials. The results show the positive impact of these materials in preventing energy losses, reducing costs and preserving nutrients in the dried product

Today, the world is looking for environmental crises and the reduction of available fossil energy sources, looking for transitioning from existing energies and turning to renewable, new and clean energies. Hydrogen as a renewable and new energy to replace fossil fuels draws attention towards has attracted This article introduces and compares the driving countries in this field. Japan is the first country to design a hydrogen economy, which has expressed its plans since 2017, and aims to completely replace current energies with hydrogen by 2050. After China and South Korea, they have been investigated. China is one of the main producers with the production of 33 million tons of hydrogen, and since 2020, it has included the importance of hydrogen in its plans and is taking steps towards a hydrogen economy. With an investment of 36 billion in this area, South Korea plans to create 30 companies and 500,000 jobs in the field of hydrogen. In 2020, the European Union introduced hydrogen as a tool to achieve the goal of zero carbon emissions and plans to replace hydrogen in three stages by 2050. Canada is also among the top ten producers with the production of 5% of the world's hydrogen, and America is also trying to compete in this arena by producing hydrogen at a price of $2 per kilogram. Finally, there is no superiority among countries in the production of green hydrogen, and all countries have started their program based on the production of blue and gray hydrogen.

For installation and the sustainable development of floating solar photovoltaic systems, it is essential to understand their components and possible designs for implementation. Moreover, their proper performance in terms of energy, economic, and environmental factors should be ensured as well as optimized. These types of systems operate in different environments. As a result, selecting components for these systems, and designing as well as implementing their various structures all have their own challenges that either directly or indirectly influence power output, durability, cost, and environmental impact. Even though floating systems are located on the surface of water sources and reservoirs, different cleaning techniques may not be applicable due to the need for high-quality water or certain environmental conditions. This study, therefore, provides a comprehensive guide to selecting components, designing and installing floating photovoltaic solar systems, as well as the necessary conditions for maintenance and different cleaning methods for these systems, by reviewing related research and various implementation plans. By using content analysis, previous studies in this field were reviewed, classified, and evaluated, and the results were prepared for researchers and decision-makers.

Widespread research has been conducted on the creation and advancement of thermal regulatory clothing as a low-cost, safe, and dependable solution, with an emphasis on application ease, comfort, and sustainability, in response to society's growing emphasis on achieving individual thermal comfort. This article examines various technologies and methods for assessing individual comfort and the performance of thermal regulatory clothing. Also, by referencing published research on the subject, it has been demonstrated that the methods used to evaluate the thermal performance of thermal regulatory clothes are complex and that determining the thermal sensation and, consequently, the individual comfort is heavily influenced by volunteers' subjective perceptions. Thus, we can conclude that the use of perception scales is necessary in field tests to evaluate thermal comfort, and therefore we can conclude that developing a reliable and widely used thermal comfort model such as Fanger’s model, which is based upon experimental results, is useful in accelerating the development and testing of thermal regulatory clothing, especially in uniform environments and under low-metabolic rate activities such as the use of thermal regulatory vests in an office environment.

Due to the rising energy demands in recent years, energy resource management has become essential. This upward trend in energy consumption can be attributed to the industrialization of countries, population growth, and the modernization of human lifestyles. Additionally, the development of urbanization and industry has led to an increase in the production of industrial and urban wastewater. The growing use of fossil fuel resources and the increase in wastewater production have prompted global environmental concerns, necessitating alternative solutions for managing these issues. Microbial fuel cells (MFCs) present a highly promising solution for wastewater treatment and clean energy production. The chemical energy of wastewater components is converted into electricity by bacteria and can be considered a reliable source for producing clean and biological electricity. This process simultaneously treats wastewater and generates green electricity, which can reduce the emissions of environmental pollutants. Although the use of this technology is still not feasible on a large scale due to economic challenges and low output power, it is anticipated that the widespread use of this technology will be facilitated by advancements in this field. In this paper, microbial fuel cells are introduced from various perspectives, including their components and different structures. Furthermore, their applications in various sectors and industries have been comprehensively reviewed, and suggestions for the future have been presented. Overall, this research can be considered a comprehensive reference for further studies in this field.

Climate change, driven by greenhouse gas emissions, necessitates a shift in how we approach fuel consumption. Since a significant portion of these emissions originates from the transportation sector, it is crucial to implement measures to decarbonize this area. Currently, a large percentage of vehicle energy is derived from fossil fuels. To mitigate pollution and combat global warming, there is a pressing need to replace conventional combustion engine vehicles with sustainable alternatives. This study provides a comprehensive review and comparison of four prominent vehicle technologies: biofuel vehicles, fuel cell vehicles, electric vehicles, and solar vehicles. Among these options, electric vehicles show the most promise for reducing CO2 emissions. Both electric and solar vehicles are recognized as practical and sustainable choices. Notably, fuel cell vehicles produce the least greenhouse gas emissions from their exhaust. However, several challenges persist, including infrastructure limitations, a shortage of biofuels, increased weight, and rapid tire wear for fuel cell vehicles. Additionally, the intermittent nature of solar power generation presents difficulties for solar vehicles, as their performance is influenced by factors such as sunlight, temperature, and shading. Electric vehicles emit fewer greenhouse gases compared to conventional vehicles, although the extent of emission reduction is contingent upon the electricity generation source. Utilizing renewable energy sources for electricity significantly lowers greenhouse gas emissions, whereas reliance on petroleum sources yields only minimal reductions.