فهرست مطالب

Energy Equipment and Systems - Volume:6 Issue: 1, 2018
  • Volume:6 Issue: 1, 2018
  • تاریخ انتشار: 1397/01/20
  • تعداد عناوین: 10
  • Rahmat Aazami, Amin Moradkhani * Pages 1-6
    In this paper, the problem of transmission loss allocation has been studied and a new method for loss allocation in transaction-based markets has been proposed. To further this end, first transmission line loss equations were used with respect to bus injected currents. The share of each bus from the mentioned transmission line losses was determined. Then, this method was applied to the total network transmission lines. While considering the available transactions, the share of each bus from the total losses was acquired. The proposed method is based on the main network relations and no simplifying assumption has been used. Finally, the proposed method is based on a typical network.
    Keywords: Loss Allocation, Sending, Receiving Power, Multilateral Transaction
  • Erfan Kosari *, Ali Rahnama, Mahyar Momen, Pedram Hanafizadeh, Mohammad Mahdi Rastegardoost Pages 7-15
    In some case of laboratory and industrial applications, various kind of measurement instruments must be placed in a conduit, in which multiphase fluid flows. Vortex shedding for any immersed body in flow field is created with a frequency, which according to flow conditions such as flow rates, geometry of body, etc. may be constant or variable. Failure may happen, if this frequency is close to one of the natural frequencies of the instruments. These flows can play a significant role in long-term reliability and safety of industrial and laboratory systems. In this study, an Eulerian–Eulerian approach is employed to simulate Air-Water two-phase flow around a rectangular probe with different volume fractions (0.01-0.5) and Reynolds numbers (1000-3000). Two-phase flow characteristics around the probe have been analyzed numerically. The results show vortex shedding in all cases with distinct Strouhal number. In addition, results illustrate that shedding is intensified by increasing Reynolds number. In order to validate the results, fraction of inlet volume was set to zero, and drag coefficient and its relation with low Reynolds number (1000-3000) in single phase flow were compared to experimental and numerical results in published article. The results show a complete agreement between the simulation and available data.
    Keywords: Two, Phase Cross Flow, Strouhal Number, Rectangular Probe, Drag coefficient
  • Abdorrahman Haeri *, Mostafa Jafari, Somayyeh Danesh Asgari Pages 16-26
    Oil is among the most effective and the largest industries in the world. Given that it supplies a large percentage of the world’s energy and plays a significant role in the national power and international credit of countries, it has a huge impact on our world today. Iran has huge oil reserves, and plays a key role in the exchange of the required energy in the world. In order to improve the performance of this critical industry, it is necessary to evaluate the performance of petroleum producing companies. The main purpose of this paper is to present the first three-stage data envelopment analysis-based approach, integrated with a balanced scorecard for performance evaluation of oil companies. Regarding the cause and effect relationships among different aspects of the balanced scorecard, its indicators are employed as input and output variables of the data envelopment analysis model and the efficiency is calculated. The results indicated that among the oil companies investigated in this paper, the National Iranian South Oil Company and Aravindan Oil & Gas Company recorded the highest and lowest efficiencies, respectively. The proposed approach by authors provides a valuable tool for managers in the oil industry to evaluate the performance and take action for performance improvement.
    Keywords: Energy Enterprise, Performance Evaluation, Balanced Scorecard (BSC), Three, Stage Data Envelopment Analysis (DEA), Oil Company
  • Hiva Sadeghi, Reza Alimardani *, Majid Khanali, Ahmad Omidi Pages 27-37
    Iran is a country completely dependent on fossil fuel resources. In order to obtain a diversity of energy sources, it requires other resources, especially renewable energy. Utilization of wind energy appears to be one of the most efficient ways of achieving sustainable development. The quantification of wind potential is a pivotal and essential initial step while developing strategies for the development of wind energy. This study presents an investigation of the potential of wind power, using two methods—Weibull and Rayleigh—at Karaj, the center of Alborz province of Iran. The wind speed data for a three-hour time interval measured over a 10-year period (2004–2015) was used to calculate and estimate the wind power generation potential. After calculating the factors related to power density and wind energy, it was concluded that data fitting via Weibull distribution was partly better than the Rayleigh distribution function. The RMSE values of Weibull and Rayleigh were respectively 0.018 and 0.013, and R2 values of Weibull and Rayleigh were 0.95 and 0.97 in Karaj for the years 2004–2015. The wind rose charts of Karaj for the 2004–2015 period show that the most prevalent wind direction is NW (North-West). The wind power density obtained indicates the region is not completely suitable for large on-grid wind farms and related investments. But the region can be suitable for off-grid applications such as water pumping and irrigation, lighting, electric fan, battery charging, and, as hybrid, with other power sources.
    Keywords: Wind Power, Wind Energy, Weibull Function, Rayleigh Function
  • Amirhossein Niroumand, Amin Ashtari Larki, Mahmoud Abbaszadeh * Pages 39-49
    In this study, ANSYS-FLUENT packages are employed to simulate the turbulent flow around DTMB4119 propeller in open water conditions. In order to form a mesh, the multiple reference frame (MRF) methodology is used. The results are compared with the experimental results and a good conformity is obtained, which endorses numerical simulation. Furthermore, the turbulence model is used, which is superior to other turbulence models in modeling marine propellers. The investigation focuses on aspects related to the influence of the pressure coefficient and the advance coefficient on hydrodynamic performance and cavitation of the propeller. The results reveal that the pressure coefficient at first decreases and then augments as it moves from the leading edge to trailing edge in the suction surface. Moreover, by increasing the blade radius and its speed, the minimum pressure increases in a way that pressure coefficient reaches its minimum value. Furthermore, volume fraction of the vapor over the blades decreases as the advance coefficient increases. As a result, the possibility of cavitation decreases.
    Keywords: DTMB4119 Propeller, Turbulent Flow, CFD simulation, Hydrodynamic Performance, Cavitation
  • Sepehr Sima Afrookhteh, Jalil Jamali *, Mohsen Shakeri, Majid Baniassadi Pages 51-59
    A 3D microstructure of the non-woven gas diffusion layers (GDLs) of polymer electrolyte fuel cells (PEFCs) is reconstructed using a stochastic method. For a commercial GDL, due to the planar orientation of the fibers in the GDL, 2D SEM image of the GDL surface is used to estimate the orientation of the carbon fibers in the domain. Two more microstructures with different fiber orientations are generated and compared. The method is verified by comparing the commercial GDL (Toray TGP-H-060) model properties with other simulations or real GDL data. Three different reconstructed models are compared in terms of permeability, and the 3D pore size distribution of the models is also investigated. Through-plane (TP) and in-plane (IP) tortuosity, and the effects of binder addition on tortuosity are also discussed. For the TGH-H-060, tortuosity is derived to be 0.93, 1.50, and 1.42 in IP-x, IP-y, and TP-z directions, respectively. It is shown that adding binders to the fibrous skeleton increases the tortuosity of the pore phase.
    Keywords: GDL Reconstruction, Fiber Orientation, Pore Size Distribution, Permeability, Tortuosity
  • Mehdi Khojastehpour *, Amin Nikkhah, Alireza Taheri-Rad Pages 61-68
    Several factors can influence the process of biogas production. The type of reactor is one of the key factors that influence biogas production. Therefore, the aim of this study was to construct a portable horizontal polyethylene-based biogas reactor. In addition, the performance of the developed biogas reactor was tested through digestion of cow manure. The experiments were carried out in Mashhad, Iran, during June–July 2016. Biogas production was studied over a span of 58 days’ hydraulic retention time. Artificial neural network (ANN) models were used to predict the production of biogas based on temperature and pH. The Levenberg–Marquardt learning algorithm was employed to develop the best model. The obtained biogas productivity was 0.27 m3 kgVS-1, indicating that the developed biogas reactor was optimum to convert the substrate into biogas. The ANN results highlighted that the best developed model consisted of an input layer with two input variables, one hidden layer with 15 neurons, and one output layer with the correlation coefficient of 0.90. Overall, it was concluded that the ANN models can be employed to prognosticate biogas production using a portable polyethylene biogas reactor.
    Keywords: artificial neural network, Horizontal Reactor, Modeling
  • Halimeh Rashidi *, Jamshid Khorshidi Pages 69-87
    Biomass gasification is the process of converting biomass into a combustible gas suitable for use in boilers, engines, and turbines to produce combined cooling, heat, and power. This paper presents a detailed model of a biomass gasification system and designs a multigeneration energy system that uses the biomass gasification process for generating combined cooling, heat, and electricity. Energy and exergy analyses are first applied to evaluate the performance of the designed system. Next, the minimizing total cost rate and the maximizing exergy efficiency of the system are considered as two objective functions and a multiobjective optimization approach based on the differential evolution algorithm and the local unimodal sampling technique is developed to calculate the optimal values of the multigeneration system parameters. A parametric study is then carried out and the Pareto front curve is used to determine the trend of objective functions and assess the performance of the system. Furthermore, sensitivity analysis is employed to evaluate the effects of the design parameters on the objective functions. Simulation results are compared with two other multiobjective optimization algorithms and the effectiveness of the proposed method is verified by using various key performance indicators.
    Keywords: Multiobjective Optimization, Exergy Analysis, Pareto Front, Biomass Gasification, Differential Evolution Algorithm, Local Unimodal Sampling
  • Seyed Erfan Hosseini-Doost, Amirmohammd Sattari, Pedram Hanafizadeh *, Morteza Molaei Pages 89-99
    Measuring the volume of a bubble, especially at its detachment, is a basic subject in gas-liquid two-phase flow research. A new indirect method for this measurement under constant flow conditions is presented. An electronic device is designed and constructed based on laser beam intensity. This device calculates the frequency of the bubble formation by measuring the total time of the formation process and counting the number of bubbles crossing the laser beam. The bubble volume at detachment can be calculated by dividing the volumetric flow rate of air by the frequency of bubble formation. The latter and the bubble volume at detachment are measured for three different heights of water above the the tip of the orifice (50, 100, and 150 mm), three orifice diameters (1, 2, and 3 mm), and different gas flow rates between 2000 and 10000 ml/hr. Comparing and validating the results with the results of the image processing (IP) method and the correlations presented by other studies shows the strong accuracy of the present method.
    Keywords: Frequency, Bubble Volume, Constant Flow, Image Processing
  • Ramin Sakipour, Hamdi Abdi * Pages 101-116
    This paper focuses on expanding and evaluating an automatic generation control (AGC) system of a hydrothermal system by modelling the appropriate generation rate constraints to operate practically in an economic manner. The hydro area is considered with an electric governor and the thermal area is modelled with a reheat turbine. Furthermore, the integral controllers and electric governor parameters are optimized using integral squared error (ISE) criterion. Also, a novel Teaching-Learning-Based Optimization (TLBO) algorithm, Particle Swarm Optimization (PSO), and Gravitational Search Algorithm (GSA) with controller are proposed for optimizing AGC. Investigations have been conducted for the selection of a suitable value for governor speed regulation parameter R for the hydro and thermal areas, to explore the effect of tie-line power on the dynamic response. The advantages of the proposed approach are demonstrated by comparing the results of optimizing the AGC system of a three-unequal-area hydrothermal system with mentioned algorithms for the first one in comparison with other recently published techniques. The results confirm the flexibility and the suitability of the proposed AGC model for optimizing the different approaches. Moreover, it is more practical to use the proposed method to make a wide variety of changes in the system parameters using sensitivity analysis.
    Keywords: Automatic Generation Control (AGC), Multi, Area Hydrothermal System, Teaching, Learning, Based Optimization (TLBO), Particle Swarm Optimization (PSO), Gravitational Search Algorithm (GSA)