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Showing 26 results for Subject: Special

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Volume 1, Issue 1 (9-2014)
Abstract

 

In this study, the performance and emission characteristics of a direct injection diesel engine using coconut oil biodiesel were investigated. For this aim, coconut oil was converted to its biodiesel via transesterification approach. Then, the effects of the biodiesel percentage in blend, engine load, and speed on brake power, brake specific fuel consumption (BSFC), nitrogen oxides (NOx), carbon dioxide (CO2), carbon monoxide (CO), and particle matter (PM) have been considered. Fuel blends with various percentages of biodiesel (0%0 - %3%) at various engine speeds and loads were tested. The results indicated that blends of cocunut with diesel fuel provide admissible engine performance on the other side, emissions decreased so much.

 
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Volume 1, Issue 1 (9-2014)
Abstract

 

Effect of open windows on car drag and consequently on the required power and fuel consumption has been investigated in this study. To do this, a simulated model as possible as similar to the actual model has been considered. For example round angles and side slopes have been considered. The drag caused by aerodynamic forces has been calculated, for different cases. Results show, as the percentage of windows opening increased, the car drag first decreased and then increased such that, the car drag with open windows for a certain percentage is equal to that of the closed windows car. This certain percentage depends on the car velocity.

 
, ,
Volume 1, Issue 1 (9-2014)
Abstract

 

The limited available energy resources and it basic role in industrial development, employing the renewable sources of energy including wind, sun, water and etcetera as appropriate choice described. Renewable energies are not only economically advisable, but even can contribute to provide a cleaner approach of energy production and healthier environment. Hence, assessment of some old structures such as Middle East wind catcher that are established on the ground of clean energies and adapting them to the modern age demands with optimizing models is noteworthy. This work, by keeping focus on calculus of variation and analysis of the wind load on the wind catcher structures and present an optimal more resistant model. Optimization of the design parameters of wind catcher structures led to a hyperbolic model with least wind catcher surface and a higher stability and strength compared with the older structures of this category.

 


, , ,
Volume 1, Issue 1 (9-2014)
Abstract

Copper oxide nanofluid that is obtained by dispersion of copper oxide nanoparticles in water base fluid is used as heat pipe working fluid. Nanofluids because of having better thermophysical properties in comparison with conventional heat transfer fluids, cause heat pipe performance improvement as an effective heat transfer equipment. In this work, a computational fluid dynamic method (CFD) is used to study the effect of using nanofluid and varying volume fraction, size and shape of suspended nanoparticles in nanofluid on heat pipe thermal performance. The results show thermal resistance reduction and heat pipe performance improvement by using nanofluid in comparison with pure water. Also volume fraction enhancement, nanoparticle’s diameter reduction and using cylindrical nanoparticles cause the evaporator and condenser temperature gradient reduction that in low volume fractions the effect of using nanoparticles with small diameter on heat transfer is more than using non spherical nanoparticles


Asghar Lashanizadegan, Mahmoodreza Rahimi, Hadie Mazlumi,
Volume 1, Issue 1 (9-2017)
Abstract

Furnaces in refinery and petrochemical processes are major consumers of energy. The most important factors for the controlling the energy consumption of the furnace can be divided into three main groups The first group includes the potential savings without cost or low cost, such as adjusting air – fuel ratio in the burner and pressure control into the furnace, The second group includes the potential savings with medium cost such as insulating body, and the third group includes the potential savings with high investment such as heat recovery from the exhaust flue. In this paper, the thermal energy savings potential on the 4 fixed- furnaces in the Loabiran companies are investigated and calculated that savings potential of adjusting air – fuel ratio in the burner is 165,973,500 Rials in the year, controlling pressure inside the furnace 95,822,300 Rials in the year, body insulation 622,167,700 Rials and recycled flue gases 929,762,400 Rials in the year. Also Loabiran companies uses regenerator that is a periodic heat recovery system to preheat the incoming air. This will result in annual savings for the daily production of 20 tons of frit, are 3,577,000,000 Rials.
Amin Moosaie, Kourosh Goudarzi, Jalil Abbasi,
Volume 1, Issue 1 (9-2017)
Abstract

Drag reduction in turbulent flows allows achieving of higher speeds and reducing energy consumption in the motion of submerged objects. An efficient technique for drag reduction uses dilute solutions of microfibers. In this paper, a review of available methods for the simulation of turbulent drag reduction by microfiber additives is presented. To compute the turbulent flow, the direct numerical simulation (DNS) technique is employed. The effect of the fibers on the flow is described by a non-Newtonian stress tensor, involving the distribution of fiber position and orientation. The fiber dynamics is governed by a Fokker-Planck equation. The computation involves a numerical solution of three-dimensional, time-dependent Navier-Stokes equations for the incompressible flow of a non-Newtonian fluid. In this article, various methods for solving the Fokker-Planck equation are reviewed.
Ali Hosseini, Ahmad Banakar,
Volume 1, Issue 1 (9-2017)
Abstract

Water shortage and energy crisis are two major challenges for human societies. Solar distillation devices the best solution for converting salt water to fresh water and saline domestic scale using free energy from the sun. This paper presents an overview of a variety of active and passive solar distillation devices for desalination of saline waters in remote rural areas with high solar radiation potential is done.
Afsaneh Ebrahimi, Sayyed Obaid Poordanesh,
Volume 1, Issue 1 (9-2017)
Abstract

The reduction of energy consumption on sensor nodes using cognitive radio network routing algorithm to help Dayjkstra, Can help a lot in increasing the life of nodes and improve the whole problem of the exchange of information without slowing down. Holes containing channel energy threshold is detected and checked by applying a range of secondary users assigned. From the simulation results of cognitive radio-based network routing algorithm can be seen Dayjkstra sensor nodes send data from the source node to the final node of their shortest and best route. Energy consumption by as much as 80 percent less sensor nodes with Dayjkstra algorithm of algorithms such as LEACH, DASC, EEUC that this factor is an increase in the lifetime of nodes in the network.
Gholamreza Karimi , Alireza Bidakhti Dehghan ,
Volume 1, Issue 1 (9-2017)
Abstract

Because of increasing demand on new reliable power source for hybrid electric vehicles, lithium-ion (Li-ion) batteries have received much attention in the last decade. Problem free Li-ion batteries are already in use for low power demand applications such as cell phone and laptop battery packs, however; for high power applications such as in automotive propulsion drives, there are serious issues which need to be addressed. Among various issues that high power application lithium-ion (Li-ion) batteries are encountered, thermal issues have received more attention because of their potential to degrade battery performance. In this work, a lumped capacitance heat transfer model is developed in conjunction with a flow network approach to study performance of a commercial-size Lithium-ion battery pack, under various design and operating conditions of a thermal management system. Air, silicon oil and water are chosen as cooling media in the battery pack. Different flow configurations are considered and temperature dispersion, cell-averaged voltage and resistance distributions, and parasitic losses due to the fan/pump power demand are calculated. It is found that application of a coolant with an appropriate viscosity and heat capacity, such as water, in conjunction with a Y-type flow configuration will result in uniform temperature and voltage distributions in the battery pack while keeping the power requirement at low, acceptable levels.
Vahab Kazerouni, Abedreza Farhadipor, Pourya Omidvar, Gholamreza Karimi,
Volume 1, Issue 1 (9-2017)
Abstract

Considering the significant waste of gas in the oil and gas industry flares, it is highly desired to recover the gas in the industrial processes. Gas recovery reduces the energy consumption as well as the negative environmental impacts. In this study, different flare gas recovery methods are presented from exergy perspectives. Exergy analysis based on the second law overcomes the limitations of the energy-based analysis and offers a much more meaningful evaluation by indicating the association of irreversibilities. Analytical results indicate that simultaneous generation of power and heat by flare gases is the most effective method and can decrease the exergy destruction and fuel gas consumption of the cycle by 77.58 MW and 5793 kg/hr, respectively. When there is no demand for power, recycling the flare gases to process units and steam generating by the turbine exhaust gases can decrease fuel gas consumption of the cycle by 5605 kg/hr. It is also observed that pressurizing and recycling the gas for utility consumption can decrease the exergy destruction and fuel gas consumption of the cycle by 28 MW and 2100 kg/hr, respectively.
, , ,
Volume 1, Issue 2 (6-2014)
Abstract

 Supersonic wind tunnels are strong and useful tools for the detection of the flow physics around flying vehicles. In this work, a blowdown type supersonic wind tunnel with a Mach number of 3 was studied. The required air for the tunnel was supplied by a storage tank containing compressed air. The intended velocity in the test section of the wind tunnel is provided by the high pressure discharge of the air from the storage tank into the atomosphere. The nozzle's geometry has been designed based on the "characteristics" method. Embedding the injector in the wind tunnel provides the opportunity to launch the wind tunnel at lower compression ratios. Since the duration of the experimental data collection is limited in blowdown supersonic wind tunnel, proper design and exploitation of the injector in a way to allow tunnel launching at decreased compression ratios, provides significant influence on the saving the compressed air of the storage tank and increasing the experiment duration. It has been attempted in this work to study the effect of installation of the injector in wind tunnel through assessing the boundary layer and the flow physics inside the wind tunnel. The results show that the injected flow increases the energy level of the low energy boundary layer, so as the energy of the boundary layer in a placed ahead of the injector location is higher than a place before the injector location. This fact results in a decreased required compression ratio for tunnel launching. The physics of the formed flow was studied and physical phenomena such as boundary layer separations, bow shock, barrel shock and mach disk were reported around the injection site 


, , ,
Volume 1, Issue 2 (6-2014)
Abstract

 

In this paper, the impact of micro bubbles as the second phase in the turbulent flow inside the channel flow has been investigated. The developed turbulent flow inside channel containing micro bubbles has been solved using large eddy simulation. Numerical analysis has been done to survey the impact of micro bubbles on turbulent characteristics derived from carrier flow. Finally, the mechanism of reducing frictional drag force was illustrated. According to the results, increasing the volume fraction of bubbles in the constant diameter will decrease the frictional drag force. Also studying the energy spectrum showed that the energy in the small scales has increased and in the large scales decreased.

 
Mohammad Hassan Shojaei Fard , Mojtaba Tahani , Ali Mahtab , Javad Zare ,
Volume 1, Issue 2 (1-2018)
Abstract

 

In this work thermal performance of a cylindrical heat pipe at steady state has been investigated empirically. The used heat pipe, made of copper, has been designed and manufactured by considering effective parameters on heat pipe thermal performance. Then heat pipe has been charged by water as the working fluid. By installing sensors and the other equipment, the test set up has been prepared. After preparing the test set up by changing voltage, various input powers have been inserted into evaporator and the heat pipe surface temperature distribution has been obtained for each case. Then by using the obtained temperature distributions, thermal resistance variations and equivalent thermal conductivity coefficient have been computed. and variation of them versus input power have been plotted. The results show that the thermal resistance has its minimum value at maximum operating limit (maximum passing power) and equivalent thermal conductivity has its maximum value at this point.
 

 
Shahram Derakhshan, Ehsan Abdolahnejad, Javad Zare,
Volume 1, Issue 2 (1-2018)
Abstract

Nowadays, according to increasing energy consumption especially in industry, the need for optimizing energy consumption and determining energy efficiency class of different devices is essential. The main challenge of the present study is developing an energy label instruction for centrifugal pumps. Since the used standard in Iran (ISIRI 7817-2, 1st.edition) only considers the effect of efficiency in energy labeling, a new method is presented to modify this standard. In the proposed method the effect of specific speed on efficiency is considered by choosing one of the constant specific speed curves in η- Q diagram and modifying efficiency for each specific speed. Then, different pumps are tested and labeled by different standards. While the used standard in Iran labels all the pumps in one class, but the new proposed method can label pumps properly as European standards that show the benefit of using the proposed method in centrifugal pumps energy labeling.
 


Rasoul Rajabpour , Bahram Sami Kashkoli , Tahereh Faraji , Abolghasem Mohamadzadeh , Seyfollah Amin,
Volume 1, Issue 2 (1-2018)
Abstract

 

In this paper, the optimal operation of pumping stations was determined using a genetic algorithm so that the minimum energy cost. The schedule for the operation of the water pump system can be a significant savings in the cost of energy to be achieved. Determine the optimum pump operation schedule an optimization model - simulation-based genetic algorithm was developed. The model integrates GA optimizer and EPANET hydraulic network solver in MATLAB. The proposed model is applied to find the optimal pump operation schedule of Dogonbadan water conveyance system from Kowsar Dam in an ordinary day of the year. The comparison of optimal schedule with ordinary operation strategy shows 26.8 percent reduction in total energy cost. This indicates the high capability of the proposed model.
 

 
Burhan Azarm,
Volume 1, Issue 2 (1-2018)
Abstract

Solar energy is the most important type of modern and renewable energies. If it displace fossil fuels, can bring an end to concerns about finiteness of fuels, environmental pollution caused by the fossil fuels, price fluctuations and energy crisis. Among the energy sources, due to the high potential of solar energies in wide areas of the Iran, it has a great importance to researchers. The base of Photovoltaic technology is to converting sunlight into electricity and nowadays, most of the countries utilize it in the forms of grid-connected and off-grid. In recent years, few technologies are used for manufacturing of solar cells. The results  of investigating show that the efficiency of the first generation in comparison to the other technologies are high due to the high quality raw materials which are used in the fabrication. It is expected that the differences between the efficiency of these for technologies will be decreased by the time and other technologies will be replaced by the first generation. In this paper, the structure of different technologies has been studied and the possible methods for improvement of the solar cells efficiency have been introduced.
 


Behrang Sajadi, Mohammad Yousefipour, Mohammad Ali Akhavan-Behabadi, Sadegh Khodaveisi,
Volume 1, Issue 2 (1-2018)
Abstract

In this study, the effect of using phase change materials on the air-conditioning system energy consumption of a typical room in a multi-floor building has been studied using EnergyPlus software. As the melting point of PCMs has an important impact on their effectiveness, as a part of this research, the effect of Iran climatic conditions on the appropriate melting point of the PCM has been investigated in 4 cities: Tabriz as a cold, Tehran as a moderate, Yazd a dry-hot and Bandar-e-Abbas a humid-hot climate. Based on the results, the proper temperature of PCM melting temperature is between 21 to 27°C and the saving varies from 1.6 to 13.2%. The results of this incestigation are useful in getting better understanding of the effect of PCMs on reducing the HVAC system energy consumption and in determining the PCM appropriate specifications.
 


Seyyed Hossein Hashemi , Ehsan Fathalinia, Mohsen Fathalinia,
Volume 1, Issue 2 (1-2018)
Abstract

The Trombe wall heating system known as one of the most important consumption reduction technology that utilizes solar energy is the energy efficiency. In this paper, the effects of temperature on system performance Trembath glass wall temperature of wall heating Trembath according to the intensity of solar radiation is investigated numerically. The results confirmed the increase in efficiency heating system with regard to solar radiation intensity emitted in the study area. With such intensity 466.281 w / m2 close to the glass surface temperature (in air duct) up to 14.422 ° C arrives while lower-intensity radiation (394.91 w / m2) in the final heat to about 12.71 ° C goes. Considering the solar radiation, can be expected to increase the flow of thermal energy in the air duct. The effect of improving the efficiency of the underlying performance heating technology Trembath wall. The results of this study, changes in temperature glass, to the the amount of solar radiation intensity in the relationship. When the radiation intensity maximum the amount of 466.81 w / m2 is concerned, more secondary radiation is emitted. As a result, the glass has a temperature range between 11.32 to the 12.73 ° C.



Neda Khani Esfand Abad, S.a.a Oloomi, S.a.a Mirjalili,
Volume 2, Issue 1 (2-2017)
Abstract

The study aimed at investigating radiation properties of multi-layers constructions including underneath layer of silicon, slightly covered by non-metal coating of silicon nitrate and silicon dioxide, and metal coating of gold, silver and cooper in temperature of 25 degrees Celsius and polarized incident radiation. Ray Transfer Matrix model was used to calculate radiation properties of multi-layers constructions as well as experimental expressions of optical constants of slightly covered silicon. The transmission coefficient of metallic coatings in polarization types of P and S and non-polarized status was zero due to low penetration power and high radiation coefficient. In non-metallic coatings, on the other hand, the transmission coefficient increased contributing to the larger penetration depth of electromagnetic waves. The overall results indicated that polarization coefficient of transmission of type P was significantly larger than Type S in non-metallic coatings. Radiation coefficient of metallic coatings was significantly larger in comparison to non-metallic coatings. As the result, they can be used in industries requiring high radiation. The results indicated that in underneath silicon layers, in room temperature and wave length of.4 to.84 micrometer, the absorption and consequently radiation coefficients were insignificant. However, silver coating indicated significantly higher absorption and radiation. In addition, the fluctuation in polarization of the incident ray of P and S type resulted in an increase in emissivity and transmission factors. The findings showed that silver in comparison to gold and cooper revealed significantly higher radiation coefficient. In radiation angle of zero (normal), radiation properties were equal for both types of S and P.


Mrs Hajar Bagheri Tolabi, Dr M.r. Shakarami, Dr E. Rok Rok,
Volume 2, Issue 1 (2-2017)
Abstract

This paper presents a new hybrid method for optimal multi-objective reconfiguration simultaneous determining the optimal size and location of Distributed Generation (DG) in a distribution feeder. The purposes of this research are reducing the losses, improving the voltage profile and equalizing the feeder load balancing in a distribution system. Ant Colony Optimization (ACO) approach as a Swarm Intelligence (SI) based algorithm is used to simultaneously reconfigure and identify the optimal capacity and location for installation of DG units in the distribution network. In order to facilitate the algorithm for multi-objective search ability, the optimization problem is formulated for minimizing fuzzy performance indices. The multi-objective optimization problem is transformed into a fuzzy inference system (FIS), where each objective function is quantified into a set of fuzzy objectives selected by fuzzy membership functions. The proposed method is validated using the IEEE 33 bus test system at nominal load. The obtained results prove this combined technique is more accurate and has an efficient convergence property compared to other intelligent search algorithms. Also, the obtained results lead to the conclusion that multi-objective reconfiguration along with placement of DGs can be more beneficial than separate single-objective optimization.



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