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Energy Equipment and Systems - Volume:5 Issue: 2, Spring 2017

Energy Equipment and Systems
Volume:5 Issue: 2, Spring 2017

  • تاریخ انتشار: 1396/03/23
  • تعداد عناوین: 10
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  • Mehrdad Shirinbakhsh, Majid Amidpour * Pages 1-10
    Biomass, as a renewable source of energy, can be used in many industries to reduce their dependence on fossil fuels. However, due to the significantly high and varied moisture content of biomass, its use has several drawbacks, such as low total efficiency and process instability. Drying biomass before combustion or gasification can eliminate these drawbacks. Besides these benefits, there are several environmental advantages of removing moisture from organic materials before disposal. In this study, a solar-assisted conveyer-belt dryer was designed to remove moisture from biomass. Economic optimization was conducted under different economic conditions to find the optimum performance of the designed dryer. The results indicated that depending on the economic condition, drying biomass with the designed dryer costs between 4 and 7 cents per kilogram of biomass. Under optimum economic operation, the solar fraction is less than 6% in both scenarios. On the other hand, by ignoring economic constraints and reducing the dryer’s capacity, solar fraction increases to more than 55%, and in this case, the drying cost will be about 11 cents per kilogram of biomass.
    Keywords: Solar Energy, Solar Dryer, Biomass Dryer, Economic Optimization
  • Pedram Hanafizadeh*, Peyman Maghsoudi Pages 11-29
    The optimal design of a plate-fin recuperator of a 200-kW microturbine was studied in this paper. The exergy efficiency, pressure drop and total cost were selected as the three important objective functions of the recuperator. Genetic Algorithm (GA) and Non-dominated Sorting Genetic Algorithm (NSGA-II) were respectively employed for single-objective and multi-objective optimizations. By optimizing the objective functions via the single-objective optimization approach, the optimum values of exergy efficiency, pressure drop and total cost were found to be 0.966, 0.846 kPa, and 302,075$ respectively, representing the best solutions obtained from 20 iterations in GA. The cases considered for bi-objective optimizations were exergy efficiency-total cost, exergy efficiency-pressure drop and total cost-pressure drop pairs for which Pareto-optimal fronts were obtained, revealing the confliction between the two objectives in each pair. Later, a three-objective optimization was undertaken to simultaneously maximize exergy efficiency while minimizing pressure drop and total cost; the results were presented in a three-dimensional Pareto-optimal front. Moreover, the results of the multi-objective optimizations (i.e. three-objective and bi-objective optimizations) were compared with those of the single-objective one. The comparisons indicated a very good match between the multi-objective and the single-objective optimum values when it came to exergy efficiency and total cost; for pressure drop, however, significant differences were observed. Eventually, a decision-making procedure was employed for the Pareto-fronts of multi-objective optimization to find the final optimal solution.
    Keywords: Recuperator, Microturbine, Genetic Algorithm, Multi-Objective Optimization, Decision-Making
  • Shahab Sabzi *, Mehdi Asadi, Hassan Moghbelli Pages 31-45
    Output power in a hybrid power system is constant while the input power with variable characteristics that is generated by different sources. Using Hybrid Electrical Energy Storage (HEES) systems, is growing rapidly since there is an obvious need for clean energy. This paper introduces different parts of a HEES system and then proposes HEES systems which employ battery, ultracapacitor and flywheel as main energy storage devices. The behavior of a hybrid electrical energy storage including battery as the main energy storage device and a diesel generator as auxiliary energy source, also battery/flywheel and battery/ultracapacitor hybrid energy storage system with purpose of supplying load with constant power is analyzed. Results of the simulation show how well ultracapacitor and flywheel can replace battery in maintaining the load with continuous power.
    Keywords: Hybrid Source, Energy Storage, Battery, Ultracapacitor, Flywheel
  • Ali Behbahani-Nia *, Rasool Bahrampouri Pages 47-61
    In this study, a reputable Kalina cycle system, KCS 11, is simulated and analysed. Within this efficient cycle, there are three heat exchangers: the first heat exchanger is designated for heat absorption from the heat source, the second heat exchanger is designed for heat release to the cold source, and the third heat exchanger is designed for energy recovery. In order to achieve precise simulation, a variation of heat capacity is considered. A finite difference method is, therefore, implemented in consideration of the amount of heat transfer in each heat exchanger. In this study, combustion exhaust is considered as the heat source, while cooling water circulates in the condenser. The effect of the product of the overall heat transfer coefficient and the heat transfer area on decisive parameters including the net power output and the efficiency is investigated. Moreover, the influences of the studied parameters are examined on two important pinch technology related curves; these are: the composite curve and the grand composite curve. The results indicated that although increasing the heat transfer surface in each of the heat exchangers boosts the power output, in some cases, it reduces the cycle’s efficiency.
    Keywords: Kalina Cycle, Heat exchanger, Thermodynamic, Pinch Analysis
  • Shekoufeh Mohammadi, Afshin Ahmadi Nadooshan *, Morteza Bayareh Pages 63-72
    The present paper reports the laminar fluid flow and heat transfer of a heated array of circular-perforated and solid fins mounted over a flat surface using the finite-volume method. One to four circular cross-sectional perforations are made along the length of the fins. The SIMPLE algorithm is used for pressure-velocity coupling and the second order upwind technique is employed to discretize the governing equations. The simulations are done for a range of Reynolds number, 100
    Keywords: Laminar Flow, Perforated Fin, Nusselt Number, Reynolds Number
  • Hosseinali Shamsabadi *, Mohammad Abedi, Desa Ahmad, Alireza Taheri-Rad Pages 73-79
    Decisions can be taken to increase energy efficiency and to mitigate the emissions to the environment by examining the energy audit and greenhouse gas (GHG) emissions footprint of crop production in different ways and in different regions, with comparable principles. In this study, energy consumption and energy indices of tomatoes production in four regions of Iran including East Azerbaijan province (open field), the provinces of Kermanshah, Tehran and Isfahan (greenhouse) were compared using related articles data. Chemical fertilizers and irrigation water in tomato production in open field and diesel fuel and chemical fertilizers in the tomato production in greenhouses system was greatest energy consumer in Iran. Energy consumption of irrigation water for tomato production in open field was markedly higher than the production in the greenhouse. In this study, the inputs of diesel fuel, chemical fertilizers, chemicals, plastics, and electricity used in the production of tomatoes, which contribute to the GHG emission footprint, were calculated via coefficients related to GHG emission. The highest and lowest greenhouse gas emissions in greenhouse tomato production in Tehran province and East Azerbaijan province farms were determined to be 13661.37 kgCO2eq ha-1 and 1274.02 kgCO2eq ha-1, respectively. Overall, tomato production in open field leads to lower greenhouse gas emissions and energy consumption per unit area, but according to more energy output in cultivation of tomato in greenhouse, energy efficiency of tomato production in greenhouse was higher.
    Keywords: Energy Efficiency, Energy Audit, Environment, Pollutants
  • Mostafa Rezaei-Shouroki * Pages 81-106
    The many advantages of renewable energies—especially wind—such as abundance, permanence, and lack of pollution, have encouraged many industrialized and developing countries to focus more on these clean sources of energy. The purpose of this study is to prioritize and rank 13 cities of the Fars province in Iran in terms of their suitability for the construction of a wind farm. Six important criteria are used to prioritize and rank these cities. Among these, wind power density—the most important criterion—was calculated by obtaining the three-hourly wind speed data at the height of 10 m above ground level related to the time period between 2004 and 2013 and then extrapolating these data to acquire wind speed related to the height of 40 m. The Data Envelopment Analysis (DEA) method was used for prioritizing and ranking the cities, after which Analytical Hierarchy Process (AHP) and Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (FTOPSIS) methods were used to assess the validity of the results. According to the results obtained from these three methods, the city of Izadkhast is recommended as the best location for the construction of a wind farm.
    Keywords: Wind Farm, Prioritizing, Optimization, Fars Province, Data Envelopment Analysis (DEA)
  • Abdorrahman Haeri Pages 105-112
    In this paper, the training needs of wind farm employees have been specified, assessed and prioritized. For this purpose, first of all, the main tasks of wind farm employees have been identified. Afterwards, four criteria—including task complexity, task importance, task time duration and task frequency—have been considered to assess and prioritize tasks. In this respect, the Analytic Hierarchy Process (AHP) has been applied to obtain weights of the criteria. Afterwards, all the wind farm employees’ tasks have been assessed on the basis of the four abovementioned criteria, and the job assessment indicator has been calculated. This procedure results in the prioritization of tasks. Finally, the appropriate training courses for the identified tasks have been specified and they have been prioritized and ranked, based on the average of job assessment indicators for the related tasks.
    Keywords: Wind Energy, Wind Farm, Training Need Assessment, Training Courses, Task Prioritization
  • Zahra Moravej*, Sajad Bagheri Pages 113-126
    This paper presents a distance protection test procedure by applying the Real-Time Digital Simulator (RTDS) of a power system. RTDS is a tool to design, develop, and test power-system protection. The RTDS enables real-time computation of electromagnetic phenomena with a calculation time step of even 50μs. The hardware allows the import and export of many signals from the simulator to an external real power-system component and, therefore, the so-called closed-loop testing. With this method, it is possible to get an insight into both the elements’ behaviour and the influence of these components on the power-system operation. The testing of a very simple impedance-protection function by the Schweitzer Engineering Laboratories protection relay is explained. Moreover, the effects of a DC offset have been tested on this relay. The test results emphasize the advantage of the RTDS for the determination of actual power-system components’ behaviour in various power-system conditions. The RTDS software, i.e. RSCAD, is used to simulate the power system models.
    Keywords: Distance Protection, DC Offset, Real, Time Electromagnetic Phenomena Calculation, RTDS
  • Sina Azami *, Maziyar Vahdaty, Farschad Torabi Pages 127-134
    The current study presents the design features and photovoltaic requirements of a floating photovoltaic plant (FPVP) whose purpose is to reduce the evaporation from the surface of a water reservoir while generating electricity. A summary of the energy budget method is also introduced to calculate the rate of evaporation from the water reservoir behind 15-Khordad dam. The top of the reservoir has a surface area about 1.59 km2 but only 2% of it has been covered with the proposed FPVP with a stated capacity of 1.45 MWdc. The study proves that covering even a small percentage of the reservoir’s surface has a significant effect on the amount of water saved annually. Finally, the average water saved monthly due to FPVP, the electricity generated by the system in the first year, and the CO2 balance of the facility are calculated based on meteorological data of Delijan.
    Keywords: FPVP, Water Reservoir, Energy Budget