Energy
Hamed Kamelnia; Afsaneh Ghalehnovi
Articles in Press, Accepted Manuscript, Available Online from 05 February 2024
Abstract
Electrochromic Glazing (EC) has seen a significant surge in adoption today, primarily attributed to its pivotal role in enhancing visual comfort, mitigating excessive heat, regulating cooling and heating requirements, and curbing lighting consumption, especially within office buildings. Moreover, electrochromic ...
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Electrochromic Glazing (EC) has seen a significant surge in adoption today, primarily attributed to its pivotal role in enhancing visual comfort, mitigating excessive heat, regulating cooling and heating requirements, and curbing lighting consumption, especially within office buildings. Moreover, electrochromic glazing effectively contributes to glare control. This research aims to explore the impact of electrochromic glazing, as compared to conventional clear windows, on both the south and north facades, with the overarching goal of enhancing thermal and visual comfort within an office complex located in Mashhad. The research process unfolds in two key steps. Firstly, a comprehensive building simulation was conducted to assess daylight performance and gauge thermal and visual comfort using the GrassHopper plugin. Ubsequently, the Honeybee and Ladybug plugins were harnessed to evaluate the Discomfort Glare Probability (DGP) index and the Useful Daylight Illuminance (UDI) index. The findings of this study underscore the compelling advantages of electrochromic glazing over conventional clear windows as a prime choice to maintain balanced daylight levels throughout the day.
In practice, using electrochromic glazing on both north and south facades of a building reduces the annual heating and cooling energy demand by 6.5% and 4.5%, respectively. Additionally, it has a significant impact on reducing intrusive light radiation and intolerable glare levels compared to reference transparent windows, with reductions of 40% and 34.52%, respectively.
Energy
H. Radaei; R. Shafaghat; S. Talesh Amiri; B. Alizadeh Kharkeshi
Abstract
Considering that the heat required for the Waste heat recovery (WHR) cycle of the engine is provided from two parts of the exhaust gas and the cooling system, the mutual influence of the WHR cycle on the engine performance is undeniable. Therefore, in this numerical study, an attempt has been made to ...
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Considering that the heat required for the Waste heat recovery (WHR) cycle of the engine is provided from two parts of the exhaust gas and the cooling system, the mutual influence of the WHR cycle on the engine performance is undeniable. Therefore, in this numerical study, an attempt has been made to thermodynamically evaluate the effect of the implementation of the WHR cycle on the engine efficiency. For this purpose, the 16 cylinder MTU 4000 R43L heavy diesel engine was simulated and a comparison was made between numerical and experimental results. Finally, the SRC heat recovery cycle was designed and applied in the simulated model according to the desired limits and the temperature range of the engine operation. At low speed with the application of the WHR cycle, the output net power did not drop much, but at the maximum speed and power, a power loss of about 4% is observed. At 1130 rpm, the power did not increase much. At 1600 rpm, the power increase is reduced to about 2.3%. At 1800 rpm, due to the significant increase in exhaust gas temperature, the total power value increased by about 4%.
Energy
F. Yazdandoost; S. A. Yazdani
Abstract
Insisting on independently providing energy due to fossil fuel availability and Economic-political purposes has imposed financial-environmental risks on countries. Inefficient obsolete infrastructures and technologies have caused devastating losses causing technical vulnerabilities in the energy sector. ...
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Insisting on independently providing energy due to fossil fuel availability and Economic-political purposes has imposed financial-environmental risks on countries. Inefficient obsolete infrastructures and technologies have caused devastating losses causing technical vulnerabilities in the energy sector. Ungainful increasing consumption of water resources has superimposed severe environmental degradation, threatening long-term energy planning. Successively, the energy security debate has turned into a challenging necessity for countries. This study developed a classic approach based on Modern Portfolio Theory (MPT) and Capital Allocation Line (CAL) reinforced with aggregated evaluative measures to deal with the financial-environmental complexities of national energy portfolios. Results prove that countries are not even aware of the risky hidden brittleness of their energy portfolio. Futuristic policymaking should be adapted to gradually change the national energy structure from fossil fuel dependency to portfolio thinking to avoid risks and achieve more security.
Energy
N. Amani; A. Sabamehr
Abstract
The purpose of this research is to analyze the energy of a residential building in the city of Tabriz with a cold and dry climate using energy simulation to provide a model to minimize energy consumption. A comparative model of energy consumption analysis in a three-story building unit with dimensions ...
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The purpose of this research is to analyze the energy of a residential building in the city of Tabriz with a cold and dry climate using energy simulation to provide a model to minimize energy consumption. A comparative model of energy consumption analysis in a three-story building unit with dimensions of 181 square meters is presented using 5 layout modes in the wall, floor, ceiling, window and door. The number of 5 designs with different arrangement of rooms and different number of windows were compared in terms of energy conservation in 51 different diagrams and the optimal energy saving design is selected. In the next step, according to the obtained results, the design of the building in the desired site is discussed. At the end, in order to check the amount of energy absorbed in the building, energy diagrams will be obtained for the thermal region of the coldest day of the year. The results show that the most optimal energy consumption of the residential building is related to the design of plan B with the fabric gains value of 41767 Wh. After that, the designed plan A show the most optimal energy consumption in the building with fabric gains value of 41028 Wh in the month of July. The results of this research are useful for energy efficiency of residential buildings and environmental management in future.
Energy
S. N. Mosavian; H. Eskandari
Abstract
This research, conducted in Gotvand, southwest Iran, evaluated the energy balance of a field system which watermelon produced in it. In the current research, energy inputs of watermelon planting were measured. To reach this goal, questionnaires were given to the farmers to record the amount of energy ...
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This research, conducted in Gotvand, southwest Iran, evaluated the energy balance of a field system which watermelon produced in it. In the current research, energy inputs of watermelon planting were measured. To reach this goal, questionnaires were given to the farmers to record the amount of energy input to their watermelon planting field. Statistical analysis of the data revealed that nitrogen was the input with the highest consumption of energy (4175 MJ.ha-1) followed by diesel fuel. About 90% of the consumed energy of watermelon planting system was seen for energies which cannot be renewed. The results showed that the efficiency of energy consumption was positive, indicating that the amount of output energy was higher than that of input energy. With each unit of energy was consumed, 4.86 units of energy were produced, which indicates high energy efficiency. For improving the efficiency of energy usage in the watermelon planting system, nitrogen application to the system should be reduced and it can be reached by suitable rotation which diminish the nitrogen needs.
Energy
J. Ahmadi; S. M. Maddahi; R. Mirzaei
Abstract
All important decisions that affect the thermal performance of the building are made in the early stages of design. Accordingly, in this research, the initial stage of architectural design which is related to space plan was targeted. The aim of this research is the perfect approach to evaluate, and optimize ...
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All important decisions that affect the thermal performance of the building are made in the early stages of design. Accordingly, in this research, the initial stage of architectural design which is related to space plan was targeted. The aim of this research is the perfect approach to evaluate, and optimize the energy a set of alternative spatial layout solutions through the functional computational design model. The method of this research includes the production of coherent design solutions and the evaluation and optimization of the energy performance of the selected solutions. In the first part, space allocation at a level produces the plan through an evolutionary technique. In the next step, certain plans were evaluated for energy performance, performance rank, and optimization. The energy simulation tool is Honeybee and Ladybug plugins,. The optimization tool is Pareto Evolutionary Algorithm in the Octopus plugin. The reproduction rate, the mutation rate and the possibility of mutation were 0.9, 0.8 and 0.2, respectively. The results showed that each algorithm is a suitable tool for design solutions, thermal performance of floor plans, helping architects’ perspective in the decision-making process, and speeding up the design process. Finally, based on the optimization, the final result of the research algorithm is 70 elite answers in the Pareto front. Only during the Pareto front optimal responses, energy consumption can be reduced by more than 30%; in daylight time and more than 39% improvement was achieved.
Energy
F. Akhlaghinezhad; H. Bagheri Sabzevar
Abstract
Considering the global energy crisis and the need to reduce energy consumption while providing thermal comfort to occupants, building performance prediction using building simulation programs requires higher accuracy of output data. Therefore, it seems necessary to study the impact of occupant behavior, ...
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Considering the global energy crisis and the need to reduce energy consumption while providing thermal comfort to occupants, building performance prediction using building simulation programs requires higher accuracy of output data. Therefore, it seems necessary to study the impact of occupant behavior, which is the main source of uncertainty in residential buildings. The traditional courtyard houses, which are recognized as a successful passive house model, respond to different climatic conditions. Therefore, this research focuses on this building type to analyze occupant window opening control scenarios and determine which control works better. For this purpose, several probabilistic controls and their effects on the adaptive thermal comfort of occupants in zones around a central courtyard were compared in the three cities of Yazd, Bandar Abbas, and Tabriz. Energy Plus was used as a simulation program for the application of Grasshopper's energy management system (EMS) along with the Ladybug and Honeybee environmental plugins. The results show that the window control algorithms can increase the adaptive thermal comfort of occupants by 25.7%, 32.2%, and 20.3% in each of the climates of Yazd, Bandar Abbas, and Tabriz cities, respectively. Indoor and outdoor temperature were the most significant variables for opening windows in the warm and cold seasons, respectively.
Energy
H. Eskandari; S. N. Mosavian
Abstract
This research, conducted in Gotvand, southwest of Iran, compared the energy consumption of two cucumber production systems: field and greenhouse production systems. In this study, energy inputs of two production systems of cucumber (including seed, pesticide, human labor, machinery, diesel fuel, electricity, ...
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This research, conducted in Gotvand, southwest of Iran, compared the energy consumption of two cucumber production systems: field and greenhouse production systems. In this study, energy inputs of two production systems of cucumber (including seed, pesticide, human labor, machinery, diesel fuel, electricity, organic manure, chemical fertilizer) were determined from questionnaires completed by farmers. The results of the experiment indicated that the energy input of the two cultivation systems was not significantly different in input energies. In both cucumber production systems, the most input energy was allocated to nitrogen fertilizer (57% and 53% for field and greenhouse, respectively) followed by diesel fuel (21% in both production systems). Non-renewable energies accounted for 90 and 88% of the total energy input to the farm and greenhouse systems, respectively. Total output energy of field and greenhouse cucumber production system was 33000 and 34000 MJ, respectively. Reducing the consumption of nitrogen fertilizer through the use of appropriate crop rotation is a suitable solution to improve energy efficiency in the cucumber production system.
Energy
M. Beykani; R. Shafaghat; A. Yousefi
Abstract
This paper investigates the effect of the immersion ratio parameter on the hydrodynamic performance of three surface-piercing propellers with diameters of 0.125, 0.132 and 0.140m at different advancing speeds. Experimental tests have been carried out in the free surface water tunnel of the Babol Noshirvani ...
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This paper investigates the effect of the immersion ratio parameter on the hydrodynamic performance of three surface-piercing propellers with diameters of 0.125, 0.132 and 0.140m at different advancing speeds. Experimental tests have been carried out in the free surface water tunnel of the Babol Noshirvani University of Technology. The results showed that the maximum thrust coefficient of three propellers occurs in the velocity range of 3-3.5 m/s. This interval represents the transition area of the three propellers. Also, the effect of the blockage ratio on the hydrodynamic coefficients of three propellers relative to the advance coefficient has been studied. By increasing the immersion depth raises the propeller's wet surface and increases the thrust and torque hydrodynamic coefficients. However, growing the propeller's diameter to 0.140m causes the effect of the blockage ratio parameter by increasing the immersion and the propeller's torque experiences a decreasing trend. Therefore, maximum propeller efficiency value with diameter 0.140m in immersion ratio 0.60 and 0.70, incresing 38% and 44%, respectively; relative to other proepllers. Also, the curve of the efficiency gradient of three propellers in the optimum immersion ratio of 0.40 compared to the advancing coefficient shows that the maximum efficiency gradient occurs in the range of 0.7 to 0.9.
Energy
H. Eskandari
Abstract
Agriculture is a system exhibiting high levels of energy consumption. Thus, energy analysis is crucial for improving the energy efficiency of agricultural systems. In this research, the input energy of an irrigated wheat production system, including seeds, machinery, fertilizer, irrigation, electricity, ...
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Agriculture is a system exhibiting high levels of energy consumption. Thus, energy analysis is crucial for improving the energy efficiency of agricultural systems. In this research, the input energy of an irrigated wheat production system, including seeds, machinery, fertilizer, irrigation, electricity, diesel fuel and human labour, were determined and thereby the net output energy, energy efficiency and energy productivity were calculated for energetic system evaluation. For reaching this goal, 110 farmers were asked to complete the questionnaires in which cultivation information such as machinery, diesel fuel, grain produced per hectare, cultivation method, the method and the duration of water supply, workers, chemical materials which were used for plant treatment. The results showed that the total input energy for producing irrigated wheat was 42,481 MJ.ha-1. Energy efficiency was achieved as 1.56, suggesting that the total output energy of the system was more than the input energy. The net output energy, indicating the rate of obtained net energy from the system, was 23,819 MJ.ha-1. Electricity and fertilizer were the inputs consuming the most energy in an irrigated wheat production system, in which 41% and 31% of the total consumed energy were devoted to electricity and fertilizer, respectively. Therefore, the appropriate management of electricity and fertilizer through advanced methods of irrigation and the precise calculation of plants’ required nutrient elements can result in the improvement of the energy efficiency of the system. Reducing seed bed preparing operations (decrease diesel fuel consumption) may also increase the energy efficiency of the wheat production system
Energy
R. Aghagolzadeh Silakhor; O. Jahanian; B. Alizadeh Kharkeshi
Abstract
Using cogeneration systems is a great way to tackle fossil fuel consumption problems. This paper introduces a Combined Cooling Heating Power (CCHP) system to recover the waste heat of an RK215 heavy diesel engine as a prime mover. Therefore the CCHP system consists of Internal Combustion Engine (RK215), ...
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Using cogeneration systems is a great way to tackle fossil fuel consumption problems. This paper introduces a Combined Cooling Heating Power (CCHP) system to recover the waste heat of an RK215 heavy diesel engine as a prime mover. Therefore the CCHP system consists of Internal Combustion Engine (RK215), a heat storage tank, and an absorption chiller. Also, the system has been studied in four modes: CCHP, CHP, CCP, and single generation. The waste heat ratio has changed due to a y factor, and the effect of this different parameter, such as the start of fuel injection and exhaust gas heat, on the system's efficiency by considering first and second laws of thermodynamic in different operating modes has been investigated. The system's highest energy and exergy efficiency in CCHP mode is equal to 50.46 and 30.8%, respectively. According to the result, as the CCHPs cooling load to the absorption chiller increases, the performance also rises. Also, the system’s carbon dioxide emissions reduction has been studied. The results showed that using different modes for waste heat recovery can reduce carbon dioxide by up to 30% approximately for different modes. Also, the fuel energy saving ratio (FESR) has been investigated, and the results showed that systems in CCHP, CHP, and CCP modes could have FESR approximately equal to 21%.
Energy
F. Najjari Seresht; A. Hakimi Oskui; S. Salkhi; E. Imani
Abstract
The building envelope is one of the most influential factors in energy consumption. Therefore, optimizing the facade of the building with new technologies is one of the most effective passive solutions to provide thermal comfort. The purpose of this research is to design a composite facade, which according ...
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The building envelope is one of the most influential factors in energy consumption. Therefore, optimizing the facade of the building with new technologies is one of the most effective passive solutions to provide thermal comfort. The purpose of this research is to design a composite facade, which according to the two main driving forces; the pressure difference caused by the heat flow (air flow and wind force) and the insulation of the air, for a residential building with a typical plan of Yazd in the hot and dry climate of Iran. That can be used to reduce the heating and cooling load of the building. For this purpose, firstly, the effect of two types of two-skin facades - floor-to-floor and all-over two-skin facades - compared to the model without two-skin facades in cooling and heating energy consumption throughout the year was modeled and analyzed with Design Builder version 6.1 software. The results of the constructions show the possibility of reducing about 60% of cooling energy through the creation of air conditioning and 26% of heating energy through the creation of thermal insulation in the residential building simulation model throughout the year by means of two combined shells. The findings of this research lead to the creation of more efficient energy solutions by creating innovation and combining new technologies according to climatic conditions.
Energy
S. Bagheri; S. A. A. Oloomi; S. A. A. Mirjalily; A. Zare-Shahabadi
Abstract
The phenomenon of nuclear boiling has always been recognized suitable for heat transfer between different boiling regimes. Study on boiling is considered as a new field which meets different research and industrial needs such as heat transfer in nuclear reactors, cooling units, rocket motors, electronic ...
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The phenomenon of nuclear boiling has always been recognized suitable for heat transfer between different boiling regimes. Study on boiling is considered as a new field which meets different research and industrial needs such as heat transfer in nuclear reactors, cooling units, rocket motors, electronic equipment cooling, batteries, etc. In this study, a chamber with immiscible fluid, water, steam, and air, having a side wall with uniform heat flux has been studied in 3D. To do so, we first considered the prediction of the heat flux interval for which the boiling occurs in the form of nuclear boiling. In this study, two-phase fluid volume (VOF) approach was used for modelling boiling on the vertical wall and two-phase flow. In this research, Ansys software package was used for numerical modelling and numerical simulation. Distribution of the velocity field follows more uniform pattern in dimensionless heights less than 0.9. In this study, bubbles are only present near a wall with heat flux that has a lower Rayleigh number. Also, existence of these bubbles on the wall, which prevents fluid infiltration, affects vortices caused by natural convection. However, the general and uniform patterns of vortices remain unchanged in most part of the fluid, which is because of the limited amount of bubbles near the wall with heat flux. Natural convection increases the height of fluid inside the chamber, which leads to the formation of stronger vortices at a dimensionless height of 0.9 that has a high Raleigh number due to high heat flux. In this case, the continuous use of heat flux gives rise to the production of bubbles over time.
Energy
N. Amani; A. Sabamehr; L. M. Palmero Iglesias
Abstract
The building sectors are recognized as one of the essential contributors of global warming and climate change because of their high energy use. The building sector is responsible for 40% of all energy usage and 40% of the CO2 emissions in the developed countries. Researchers in the world are working ...
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The building sectors are recognized as one of the essential contributors of global warming and climate change because of their high energy use. The building sector is responsible for 40% of all energy usage and 40% of the CO2 emissions in the developed countries. Researchers in the world are working on energy management and conservation using simulation software to develop strategies that lead to an overall reduction of energy consumption in the buildings. This review is considered a modeling and simulation approach with a specific focus on residential building. Modeling and simulation methods reviewed are presented categorically as per the strategic approach adopted by the researchers. Simulation results available for residential building energy are also introduced. This research has reviewed the capabilities and performances on Ecotect simulation and modeling, including daylighting, solar radiation, thermal analysis, and shading for energy management and conservation of residential building. Different modeling and simulation approaches, from various building and climate, were reviewed and discussed. The analysis of present work greatly help the researchers' decision-making and selection of software to perform various simulations in energy management of residential buildings.
Energy
S. A. Gandjalikhan Nassab
Abstract
This paper deals with the development of compound parabolic collectors (CPCs), utilizing a partial glass sheet adjacent to the absorber plate for the purpose of performance improvement. The collector under study has a parabolic shape, whose cavity is filled with air and the turbulent natural convection ...
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This paper deals with the development of compound parabolic collectors (CPCs), utilizing a partial glass sheet adjacent to the absorber plate for the purpose of performance improvement. The collector under study has a parabolic shape, whose cavity is filled with air and the turbulent natural convection takes place because of the air density gradient. The main goal is the reduction of heat losses by keeping away the high-temperature region near to the absorber from the main recirculaetd convection airflow by installation of a separating glass sheet. The conservations of mass, momentum and energy as the set of governing equations for the steady and turbulent free convection airflow in the CPC’s cavity and the Laplace equation for computation of temperature distributions in solid parts including the glass cover, absorber plate, and glass sheet were numerically solved by the finite element method. The COMSOL Multiphysics software was used for the present simulation. For the computation of turbulent stress and heat flux, the κ-ε turbulence model was employed. An attempt was made to investigate the installation of a fully transparent glass sheet near the absorber plate on the thermal behavior of the studied CPC. It is expected that this factor leads to lowering the heat losses from boundary surfaces, especially from the glass cover. Numerical findings showed about a 24% increase in the efficiency of studied test cases because of the installed glass sheet. Comparison between the theoretical findings with experiment shows good consistency.
Energy
S. Abdoli Naser; F. Haghparast; M. Singery; H. Sattari Sarbangholi
Abstract
Most of today's buildings, due to improper imitation of the architecture of buildings in other countries, are forced to use more energy to create conditions of thermal comfort. Building windows affect energy efficiency. So, the aim of this research is to be concerned with Tabriz climate; in selecting ...
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Most of today's buildings, due to improper imitation of the architecture of buildings in other countries, are forced to use more energy to create conditions of thermal comfort. Building windows affect energy efficiency. So, the aim of this research is to be concerned with Tabriz climate; in selecting the proportion and suitable glazing of the windows, in order to access the best design and execute a model to decrease energy consumption. The research approach is to utilize simulation and Design Builder software as a research tool. So, the annual gas consumed in the Building was received from the National Iranian Gas Company and a case study is modeled and after converting the unit from kWh to kg and kg to m3 and reliability of simulation results. Then, through parametric optimization, eight scenarios in designing windows and through the genetic algorithm, the glazing coating were evaluated. The simulations were performed again and the results index was examined. Eventually, based on the analysis of outputs, according to fixed area, it is more suitable to replace windows with the height of 1.5 to 1.74 meters instead of windows with the height of 1 or 1.2 meters. A window should be replaced with 2, 3, 4 or 5 windows with the same fixed area. I is desired to superseded triple-glazed glazing with low-emissivity filled with argon gas with clear double-glazed glazing filled with air to reduce energy consumption. The amount of heat losses for the window height of 1 to 1.5m, from one window to five windows and for the clear double-glazed glazing filled with air were 2.04%, 11.11%,. and 45.36%, respectively.
Energy
H. Bagheri Sabzevar; Z. Erfan
Abstract
Today’s energy consumption is one of the most important causes of pollution around the world. Considering the building sector consumes the most energy, it should be seriously considered. In order to provide thermal comfort inside a building, energy is consumed, which can be managed using tools ...
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Today’s energy consumption is one of the most important causes of pollution around the world. Considering the building sector consumes the most energy, it should be seriously considered. In order to provide thermal comfort inside a building, energy is consumed, which can be managed using tools such as louvers that allow solar radiation to pass through the windows while reducing the amount of consumed energy. The goal of this paper is to find the optimal features for shading device of fixed louvers for the east, west, and south facades of the office building at Hakim Sabzevari University in terms of thermal efficiency using parametric analysis. For one year, three rooms on three floors of this building with window louvers at different depths, angles, and distances were thermally simulated with EnergyPlus software and the HoneyBee plugin in addition to the Galapagos plugin for optimization. Based on the optimized samples, it is possible to reduce the thermal energy consumption by 32.34%, 23.71%, and 30.2%, respectively using the ideal louvers on the east, south, and west facades. In terms of thermal efficiency, the distance between the blinds on the south facade and the angle between them on the east and west facades of a window louver are the most significant factors.
Energy
J. Chen; Y. Haijun; L. Hao; Z. Zhifang; L. Mei
Abstract
Taking Shanxi fat coal, Shanxi 4# coke coal and Shenmu low rank pulverized coal as raw materials, three different concentrations of NaOH modified corn stalk were used as binder. The effect of changing NaOH concentrations and coal particle size used in moulding briquette and formed coke on its SEM ...
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Taking Shanxi fat coal, Shanxi 4# coke coal and Shenmu low rank pulverized coal as raw materials, three different concentrations of NaOH modified corn stalk were used as binder. The effect of changing NaOH concentrations and coal particle size used in moulding briquette and formed coke on its SEM micrographs, combustion property and FTIR absorption strength were investigated. The micro-properties of corn stalk before and after modification was also discussed. Results showed that the moisture content and ash yield of modified corn stalk increased obviously and the volatile yield showed opposite trend. 2.0% NaOH modified corn stalk showed more voids or porosity which could wrap a large number of coal particles to form strong strength briquette. Addition of modified corn stalk could reduces the briquette burning time and increased burning rate with strong flame and good ignition. From SEM micrograph, briquette had rough surface, and different sizes coal particles and fiber were bound together firmly. Formed coke showed light gray metallic luster, light mass, obvious circular holes and small gaps among particles.The melting colloid and binder could better infiltrate and encapsulate coal particles to form a dense and impermeable entity, which blocked the channels of organic group decomposition during pyrolysis process. Thus, it is forming many holes of different sizes on the surface and inside formed coke. The infrared spectrum of formed coke was simplier than briquette, and the absorption peak number was less and absorption strength was weaker also.
