Showing 15 results for Power Plant
Jamasb Pirkandi, Majid Ghassemi,
Volume 13, Issue 15 (3-2014)
Abstract
The purpose of this study is thermo-economic analysis of a combined fuel cell and micro gas turbine power plant cycle for using in small scale CHP systems. Since the fuel cell is the main source of power generation in hybrid systems, in this study, complete electrochemical, thermal and thermodynamic calculations are performed to obtain more accurate results; and unlike most studies, the cell temperature is not assumed constant. The performance analysis of the hybrid system shows that increasing the pressure and air to fuel ratio, causes to loss of electrical efficiency and increase in the electricity price because of reduction in cell and turbine inlet gas temperatures. The other results of this study show that considering the economic life of the system, making use of this type of hybrid systems is economical and generates less electricity price in comparison with micro gas turbine.
Shahram Derakhshan, Mohammad Bagheri, Ehsan Abdolahnejad,
Volume 14, Issue 2 (5-2014)
Abstract
In the present paper a micro-pelton turbine with very small dimension has been studied. This micro turbine was designed for 15 kW output power and was utilized in KhorasanRazavi. To analyze and evaluate the efficiency and effectiveness of physical and geometrical parameters, the turbine flow was simulated using the commercial software Ansys CFX 13 and the simulation results of the performance point were compared and evaluated with experimental results. Because of complexity of simulation and heavy computation, instead of entire turbine, just a part of it containing several buckets was simulated. A 3D transient flow simulation was applied using the SST turbulent model. In order to model two-phase flow, the standard homogeneous free surface model was employed. In the results the effect of rotating speed on the efficiency was investigated. Moreover, the effect of physical parameters: flow rate and head and geometric parameters: the distance from nozzle to the axis of buckets, the number of buckets in constant pitch circle diameter and constant bucket size, the number of buckets in constant pitch circle diameter and variable bucket size and the number of buckets in variable pitch circle diameter and constant bucket size on the performance of a micro-turbine was investigated.
Vahid Khalilzadeh Bavil, Javad Mahmoudimehr,
Volume 15, Issue 10 (1-2016)
Abstract
This study is concerned with optimizing the daily operation of a solar power plant equipped with thermal energy storage system (TES). The modeling is performed by solving a set of non-linear governing equations and is verified through comparison with the literature. "Maximum production period" and "maximum revenue" constitute the objectives of the optimization study which are first considered individually (as two single-objective problems) and are then considered simultaneously (as a multi-objective problem). Genetic Algorithm (GA) is employed as the optimization tool. The results of the first objective (maximum production period) shows 7 hours increase in the daily production time as a result of employing the TES system. This occurred through saving energy during the times of high solar radiation and using the stored energy for electricity generation during the times of low or zero solar radiation. The results of the second objective (maximum revenue) indicate 13.5% increase in the produced profit as a result of employing the TES system. This improvement was resulted from saving energy during the times of low electricity price and using the stored energy for maximum electricity generation during the times of high electricity price. Finally, in the multi-objective study, 5 hours increase in the production period and 8.1% increase in the revenue were simultaneously obtained as a result of a proper tradeoff between the two objectives.
Shahed Taghian Dehaghani, Hossein Ahmadi Kia,
Volume 16, Issue 4 (6-2016)
Abstract
Wet cooling towers have a high cooling capacity. However, owing to consumption of large water quantities in wet cooling towers, using them in arid regions facing water resource crisis might cause operational problems. In this research, changing the wet cooling tower of unit 5 of Isfahan Islamabad power plant into a hybrid cooling tower, using parallel path wet/dry configuration is studied. The hybrid cooling tower with the recommended configuration causes minimal changes in the other power plant facilities and has a low construction cost. Two different airflow control systems are investigated for the wet and hybrid cooling towers. In the first system, the amount of airflow rate in the cooling tower is adjusted by means of switching tower ID fans on or off. In the second system, an optimum airflow control mechanism with high-tech fans is devised. The results reveal that the optimum airflow control system is more suitable than the other system, due to less water consumption, preventing the sudden fluctuations of airflow and consequently water consumption rates and less fan power consumption. Experimental data and results obtained by the HTFS software are used for validating the simulated results of the wet cooling tower and air-cooled heat exchangers, respectively. The results demonstrate that the annual amount of water conservation due to changing the wet cooling tower into hybrid tower is approximately 343830 and 348718 cubic meters for fan switching and optimum airflow control systems, respectively.
Milad Moradi, Ali Chaibakhsh, Amin Ramezani,
Volume 16, Issue 10 (1-2017)
Abstract
In this study, an application of support vector machine (SVM) for early fault detection in increasing the level of the start-up vessel in a Benson type once-through boiler during load changes is presented. The level increasing in the start-up vessel is happened due to thermal conditions disruption inside the boiler especially while the unit load is ramped-down. In this regard, first, the variables effective on increasing the level of start-up vessel was identified based on experimental data from a power plant unit, then the dimension of input variables was reduced by selecting appropriate features. Experimental results show that the hotwell surfaces’ temperature could be considered as the most appropriate indicator for steam quality deterioration. By comparing the extracted features from healthy and unhealthy conditions, appropriate fault model was developed using SVM with radial basis function (RBF) as the kernel. The performances of fault detection system were evaluated with respect to the similar faults at two different time periods happen in a steam power plant. The obtained results show the accuracy and feasibility of the proposed approach in early detection of faults during the unit’s load variations. Advantages of the proposed technique is preventing false alarm in power plants’ boilers as load changes.
Mostafa Baghsheikhi, ,
Volume 18, Issue 2 (4-2018)
Abstract
Electricity generation and consumption are the indicators of industrial development in each country. Most of the electricity generation in Iran is produced by the steam power plants. Optimum regulation of various parameters leads to the best operation of these power stations. Mass flow rates of the turbines extractions are one of the factors that effects on the fuel consumption and produced electricity of the power plant. The aim of this paper is the optimization of steam power plants by regulation of turbine's extractions mass flow rates in an optimum state. On the other hand, optimization of complex energy systems such as power plants by usual mathematical methods is very time-consuming. In this research, after the energy and exergy analysis of the Shahid Rajaei steam power plant located in Iran, optimization of the plant will be done by one of the soft computing methods namely as the genetic algorithm. Using this method, the profit of the power plant at 60, 80, and 100% of the nominal power was increased 2242080, 2575360, and 1223840 $ per annum, respectively.
Mehran Abdolalipouradl, Shahram Khalilarya, Samad Jafarmadar,
Volume 18, Issue 4 (8-2018)
Abstract
The use of new energies, including geothermal energy, is rapidly devoloping in the world. In Iran, the Sabalan area has a great potential for generating energy from geothermal energy sources. In this paper, a new power generation combined cycle (flash combined cycle with supercritical carbon dioxide and organic Rankine cycle) is proposed with respect to two wells with different temperatures and pressures for Sabalan geothermal sources. For the organic Rankine cycle, four fluids are considered appropriately and then proposed combination cycle is investigated by energy and exergy analysis. In this study, a new method proposed for the determination of Pinch point for carbon dioxide heat exchangers. In the end the proposed cycle has been optimized relative to seprators pressure, the second evaporator temperature and the carbon dioxide cycle pressure ratio. The results show that the n-butane agent has been selected as the most suitable fluid for the Rankine cycle. For the optimal condition, the net power of the proposed cycle is 19934 kW, the cycle efficiency will be 17.05% and the exergy efficiency will be65.38 %.The results of exergy analysis show that the low pressure turbine in geothermal have the highest value of exergy destruction. The results show that net power output, energy and exergy efficiencies of the proposed cycle in this paper is 15.29 %, 17.06% and 18.35% higher than the corresponding values obtained for the previously proposed system.
S. Khajepour , M. Ameri,
Volume 19, Issue 1 (1-2019)
Abstract
In this research, the effect of using two solar fields in a solar thermal power plant was evaluated. The average price of natural gas in the last decade was 3.5 dollar/MMBTU. Due to the complexities of the solar power plant, two methods were introduced to optimize the area of the solar fields. Then, for further evaluation of the solar power plant with two distinct solar fields, the plant was examined for two natural gas prices of 3.5 and 9 dollar/MMBTU. The results of the study show that the use of two separate solar fields to produce high pressure steam turbines and low pressure over the use of a solar field reduces the cost of generating electricity. Although each solar field must produce different energy quantities, and the area of each of the fields is different, the size of the field coefficient of the field was the same for both solar fields.
M. Abdolalipouradl , Sh. Khalilarya , S. Jafarmadar ,
Volume 19, Issue 2 (2-2019)
Abstract
In northwestern Iran, two wells with different temperature and pressure conditions have been exploited in Sabalan region. According to the thermodynamic properties of wells, the combined cycle (flash combined cycle with transcritical CO2 and Kalina 11) is proposed for Sabalan geothermal. In the Kalina 11 and transcritical CO2 heat exchangers, in which the fluid temperature is rising, there is a different temperature variation gradient, therefore, a new method is proposed for the determination of pinch point and other thermodynamic properties. The effects of the Kalina high pressure, amoina concentration, transcritical CO2 cycle pressure ratio, pinch points temperature difference and separators’ pressure on the thermal and exergy efficiencies of the proposed combined cycle were studied, Finally the proposed combined cycle was optimized thermodynamically using the EES (Engineering Equation Solver) software. Based on identical operation conditions, the net power of the combined cycle is 20046 kW, the thermal efficiency is 17.15%, the rate of exergy destructions is 8259 kW and the exergy efficiency is 65.74%. It was found that the net power output, the thermal and exergy efficiencies of combined cycle are about 17.55%, 17.55% and 18.35% higher than the previously proposed system.
M. Aligholami , A. Rostamzadeh Khosroshahi ,
Volume 19, Issue 10 (10-2019)
Abstract
The aim of this study is the modeling of the solar chimney for achieving the relation between turbine output power and geometrical parameters. In this regards, 9 different models are determined based on the variety of chimney height and diameter for investigating the effects of geometrical parameters on the turbine performance. As well as, in order to improvement of system performance, the hydrophobic surfaces were evaluated with consideration of friction reduction by verification of slip condition on walls. The k-ε turbulent model was used to modeling turbulence flow and reverse-fan model was employed for simulating the turbine. For this purpose, the extracted data from the mass flow rate and velocity changes were validated with prior studies and then were compared in different pressure jumps in order to better comprehension of the performance of the turbine. The optimization was done through the defined models and it was observed that to have a better and optimized design, the geometrical parameters should have been considered in the system design simultaneously. Meanwhile, the chimney diameter should have been paid more attention as one of the most important design parameters. Also, the precise correlation was represented to estimate the turbine output power with respect to the height and diameter of the chimney. Furthermore, based on the applying of slip condition on walls for simulating hydrophobic surfaces, shear stresses reduction was done and it was revealed that the hydrophobic surfaces could have a positive effect on the performance of SCPP up to 5 percent.
Z. Javadi, M. Miansari, B. Ghorbani,
Volume 19, Issue 12 (12-2019)
Abstract
Regarding the water and energy crisis, improving the efficiency of thermal systems and heat recovery, along with the use of desalination process, has attracted the attention of many researchers in recent years. For this purpose, thermal desalination process and solar collectors were used in steam power plants. In this study, an integrated structure for simultaneous generation of fresh water and power has been developed using a combination of solar collectors, steam power plant for power generation, ORC cycle, and thermal multi-effect desalination cycle. The integrated structure has the capacity of producing 762.6 kg / s of fresh water, 104.1 MW of power in the rankine cycle and 306.7 MW of power in a steam power plant. In this integrated structure, the efficiency of the steam power plant is 37.24% and the total exergy efficiency is 78.54%. Exergy analysis of the integrated structure shows that the highest destruction of exergy in solar collectors and heat exchangers are equal to 45.2% and 37.27%, respectively. The economic analysis of the developed integrated structure shows that the period of return is 3.838 years, and the prime cost of the product is 0.0325 $/kWh. Moreover, the impact of various parameters on the performance of the integrated structure was investigated using sensitivity analysis.
M. Abdolalipouradl, Sh. Khalilarya, F. Mohammadkhani,
Volume 20, Issue 2 (1-2020)
Abstract
In the present study, a new combined cycle (including a two-step flash evaporation, the Kalina cycle, and a proton-exchange membrane) for simultaneous power and hydrogen generation from Sabalan geothermal wells has been proposed and analyzed from the viewpoints of energy and exergy. The effects of important parameters including separators pressure of flash evaporation, the minimum temperature difference in the pinch point, Kalian higher pressure, superheated geothermal fluid, the ratio of consumed power for hydrogen production and dead state temperature on the amount of produced hydrogen, the net generating power, thermal and exergy efficiencies of the proposed combined cycle have been studied. The results show that for the investigated case in the proposed combined cycle, the amount of the produced hydrogen, net generating power and energy, and exergy efficiency were 1536kg/hr, 12.83MV, 11.39% and 43.64%, respectively. Increasing the pressure of the separators was not effective in increasing hydrogen production, while with increasing the first separator pressure, as well as, the second separator pressure to the optimum pressure, the thermal and exergy efficiency increase. With increasing the temperature of the proton membrane electrolyzer, the produced hydrogen discharge increases and while maintaining cycle net output power, thermal and exergy efficiencies increase. Also, at the optimum point for high-pressure Kalina, the maximum amount of hydrogen production is obtained. The highest amount of exergy degradation was obtained for the protonated membrane electrolyzer, evaporator and condenser 2, respectively.
Z. Karamimehr, A. Rabiee,
Volume 20, Issue 3 (2-2020)
Abstract
The operation of power generation cycles and their related events are one of the main issues in the field of safety of power plants. If these events are not properly managed for any reason, the consequences will be irreparable. In the meantime, the operator action can be one of the most effective factors in the management of the accident. In this research, the operator action has been evaluated in the main steam line break connected to the turbine and total loss of steam generator feed water for the Bushehr power plant. Firstly, the data has been validated in both steady and transient states with the final safety analysis report of the power plant of Bushehr as a reliable reference. The results indicate a good agreement with the final safety analysis report. In the next step, the operator action has been evaluated to mitigate the thermohydraulic parameters, including temperature and pressure. Finally, by performing an operator sensitivity analysis in the main steam line break connected to the turbine followed by total loss of steam generator feed water, the maximum possible time for operator intervention has been estimated 76 minutes.
Volume 21, Issue 2 (7-2017)
Abstract
South Khorasan is a less developed region in Iran and due to long distance to the center of the country and being located at the endpoint of energy transmission networks, energy transfer to this province is unstable and expensive. Hence, South Khorasan is a suitable region for the deployment of renewable energy (RE) technologies. Solar energy has a higher priority among other RE-based resources in this province because of the climatic and geographical conditions of this region. In this research, the optimal sites for PV power plants in Birjand County are determined. First, the set of factors and criteria influencing the site selection of PV power plants was defined. Having prepared and processed spatial data and maps, unsuitable areas were eliminated using Boolean logic model. Remaining areas were rated based on technical, socio-economic, and environmental criteria by means of different fuzzy membership functions. Then, these rated areas were mapped. To identify the optimal sites for the on-grid installations of PVs, fuzzified maps were overlaid by fuzzy gamma operator. Finally, the pixels of the final map were classified into five groups based on their fuzzy values. The results show that 0.5 percent of Birjand County areas are optimal for the establishment of PV power plants.
Afshin Abdollahian, Mehran Ameri,
Volume 21, Issue 5 (4-2021)
Abstract
Supplementary firing system is one of the common methods of increasing the power generated of combined cycle units. Low cost of investment to the rate of increase of the generative power has encouraged the designers to use this method in the above power plants. In this article, field study of the performance changes of a real combined cycle unit with and without supplementary firing has been performed from energy and exergy viewpoints. Studies show that in all operation modes subject to research, using supplementary firing causes an increase in power generation up to 26.3MW, energy efficiency of steam cycle about 2.43% and decreases the exergy destruction of steam flow control valves. But this system has a negative impact on energy and exergy efficiencies of the whole combined cycle, which at the worth case about 1.17% decreases energy efficiency. In addition, it was specified that the power plants operation in the partial loads causes high exergy destruction in the cycle which steam cycle increased energy and exergy efficiencies due to use supplementary firing system cannot fully compensate it.
