International Journal of Energetica
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Performance study and analysis between vector control and direct power control for DFIG based wind energy system
Get PDFThis paper concentrates on analyzing the performance of the two most important techniques of independent active and reactive power control of the doubly-fed induction generator used in a variable speed wind power conversion system. In the first technique, the independent control of the active and reactive power is based on the vector control technique by the orientation of the stator voltage space vector using PI controllers; the decoupling components are deduced along with the d, q axes; and the PI controllers' parameters are calculated from the mathematical model of the doubly-fed induction generator. Hysteresis controllers are utilized to designing a direct power control technique. The performances of the studied control methods are tested and compared via simulation results
Solar thermo-chemical process assisting a pressure oxidation process for co-production of electricity and metal
Get PDFThe mining industry is looking at the use of solar energy to address issues related to highly variable energy prices, falling ore grades, and increasing concern about the industry’s carbon footprint. The pressure oxidation of ore sulfides is an economic alternative to the smelting process because it has the potential to reduce energy consumption and treat low-grade ores. In the pressure oxidation of ore sulfides, the purity and utilization of oxygen are key factors. Indeed, oxygen production and consumption constitute the major operating cost of the pressure oxidation process. Solar thermo-chemical looping processes have been identified as one of the most efficient pathways for the production and storage of oxygen. This study investigates the integration of a solar thermo-chemical looping process with a pressure oxidation process to treat ore sulfide and produce electricity. The analysis shows that the temperature of the cold storage tank has a strong influence on the performance of the complete system. The increase in the cold tank temperature results in a sharp decrease in the size of the receiver. This reduces the investment costs for both the solar receiver and the heliostat field. For the considered case, the useful heat of the solar receiver is 3.7 MWth when the cold tank temperature is set at 100°C. If the cold tank temperature is set at 400°C, the required useful solar heat is about 3.1 MWth and the nominal output of the gas turbine is 0.56 MWe. The analysis showed that about 80% of the useful solar heat can be used to generate oxygen when the temperature of the cold tank is as high as that of the reduction reactio
Dynamic modelling of an earth-to-air heat exchanger for air cooling on the building in hot temperate climate of Beni Mellal Morocco
Get PDFIn this article, we examined the passive cooling techniques built into a building in hot temperate climate. Our work aims to reduce the energy demand for cooling and progress the thermal comfort of building by decreasing overheating hours. The dynamic simulations of the energy performance in a building with an earth-air heat exchanger (EAHX) are performed in the summer period using TRNSYS software. The building is situated in Beni Mellal city (Morocco) where the climate is a hot temperate one. The results of the simulations show a significant potential for air cooling. Indeed, for the hottest day of July (retained for this study), when the outside temperature is 44.8 °C and the cooled temperature (inside) is 29 °C, the difference of 15.8 °C is obtained. Also, an evaluation of the relative humidity is provided. Finally, we recommend that the Moroccan thermal code encourage the use of passive cooling techniques; precisely in temperate climate
Literature review: synthesis of CuO (Copper Oxide) nanoparticles for thermal energy storage
Get PDFThis paper aims to provide a discussion of the methods used in the synthesis of CuO nanoparticles. A review of the CuO nanoparticle synthesis method was carried out from 65 articles from 2000 to 2021. The CuO nanoparticle synthesis methods described in this paper are electrochemical, sonochemical, sol-gel, biogenic, green synthesis, and hydrothermal methods. Each method used to synthesize CuO nanoparticles has advantages and disadvantages. Based on their advantages, electrochemical, sonochemical, green synthesis, and biogenic methods are environmentally friendly methods. Moreover, the hydrothermal and biogenic methods are simple methods with easy preparation. In its utilization, CuO nanoparticles can be used to divert heat energy. The addition of a volume of CuO nanoparticles into the nitrate salt can increase the thermal diffusivity and thermal conductivity used in solar power plants. Among the methods described, the hydrothermal method is the most effective and efficient technique. This is because the method is simple (without using any surfactant template), easy to vary the temperature, reactant concentration, and time variables on the growth of nanostructures. This paper is expected to provide some considerations regarding the synthesis method of CuO nanoparticles that can be used on an industrial scale based on the advantages of each method
Bioclimatic approach of passive cooling techniques for the design of buildings in southern Algeria
Get PDFThe bioclimatic approach looks into the opportunities for building conception under the local climatic conditions. The first bioclimatic chart has been developed by Olgyay which combines temperature with relative humidity to characterize the comfort zone. It is founded on outside climate conditions to identify attenuation measures such as solar radiation, wind speed, or shading to reach comfortable inside conditions. Givoni created also a bioclimatic chart founded on inside conditions using the physical and thermal properties of air. Bioclimatic approach strategies contribute to decreasing the building energy loads and increasing thermal comfort for its residents over the year. The principal aim of this research is to evaluate a bioclimatic approach to passive cooling for building design in Algeria's South using Givoni's Bioclimatic chart and Olgyay's Bioclimatic chart. Climate data of various locations (Ouargla, Ghardaia, and El Oued) within this area were collected and analyzed. Furthermore, an overview of appropriated conception strategies for the hot season for each zone is developed. The results show that the maximum average temperature from June to August at around 43.1°C. After applying passive cooling strategies, the temperature indoor can be decreased from about 26.1 to 31.4°C, which can be described as being in the comfort zone for the three studied locations. Finally, these findings can contribute to understanding the thermal behavior of residential buildings and offer guidelines to develop a convenient concept of what the building composition should look like in arid and hot climates
Organometallic Perovskite Solar Cell
Get PDFHalide organometallic perovskite has an important role in the efficiency increase of the solar cell. Thus in this work, we formed the basic nucleus of the organic perovskite, and we studied its morphological properties. The X-ray diffraction result shows that this compound is consistent, homogeneous, and has preferential orientation growth be at (100) plane, which means that the experimental conditions which we worked on were optimal. After adding both tin iodide and methylamine chloride in organic solvents (DMF and DMSO). Deposited this mixture by spray pyrolysis method at Specific temperature 120C°, on the glass substrate, a thin black layer formed; the result of X-ray diffraction on this latter layer showed that it is a spectrum of perovskite compound, which has preferential orientation growth be at (110) plane. Via optical proprieties, it found that has low gap energy of 1.78 eV, and transmittance of 1,6% furthermore it has a high absorption coefficient of 8.104 cm-1, in the visible domain. But it has a relatively high value of Auerbach energy 0.6 eV due to the crystal defects. So this compound could be an active layer in the solar cell
4E (Energy-Exergy-Economic-Environmental) performances assessment of different configurations of power cycles
Get PDFSteam power plants are alimented by different sources of energy including fossil fuels or renewable ones such as solar thermal, biomass or geothermal. Thus, thermodynamic, economic and environmental analyses of different steam power cycles are highly required for identification and choice of the most effective and viable layout to be adopted in the installation. Consequently, the main aim of the present paper is to compare five different configurations of power cycles in terms of energy and exergy efficiencies, fuel and cooling water consumptions, CO2 emissions rate, as well as investment and operating costs, and net present value (NPV). The obtained results present relevant differences; the energy and exergy efficiencies of the fifth configuration similar to the one of Achouat power station are the highest with 41.9% and 39.5% respectively. On the other hand, this configuration shows better environmental performances represented by CO2 emission (46.12 kg/s), and water consumption for cooling (7.42 m3/s). Economically, there is a clear convergence in the NPV values for configurations with Reheating and Regeneration processes. Moreover, the fourth configuration is the best in terms of net present value (NPV) of 103.1(M€)
Parametric Study of the Effective parameters on the Performance of Solar Chimney Power Plant
Get PDFThe solar chimney power plant (SCPP) is an effective option for electrical energy production from solar energy. In this paper, a numerical model to predict the SCPP performance is developed. The effects of collector angle and solar radiation are investigated on the parameters of air as the velocity and temperature. The study shows that when the collector angle is 20°, the velocity maximum is 1.8 m/s at the chimney base and the maximum temperature is 332.1k. in addition, increased solar radiation produces an increase in temperature (from 400 w/m² to 900 w/m²) and air velocity (from 22.25 m/s to 2.75 m/s) in the solar energy towe
Effect of the fluidic injection on the flow of a converging-diverging conical nozzle
Get PDFThe flow in an Over-Expanded Nozzle is subjected to shock waves leading to the unsteady separation of the boundary layer. Free detachment may be followed by a restricted detachment. During the expansion regime in propellant nozzles, several physical phenomena are encountered: supersonic jet, jet separation, adverse pressure gradient, shock wave, turbulent boundary layer, highly compressible mixture layer, return flow, large scale turbulence. These very complex phenomena can considerably affect the performance of the nozzle.The numerical investigation was performed by the CFD-FASTRAN search code, using the k-w SST model as the turbulence model. The calculation is performed by solving the Navier-Stokes equations of two-dimensional compressible turbulent flow. It is based on the study of the fluidic vectorization phenomenon of the thrust of a double-injection convergent-divergent supersonic conical nozzle. The study is based on the effect of the ratio of NPR pressures with SPR = 1 on the overall structure of shock waves. The calculation is highlighting the behavior of a flow that has not neglected. In particular, the appearance of the separation zone formed by the fluid jet and the deflection of the main jet cause separation shocks
Modeling solar desalination with reverse osmosis (RO) powered by concentrating solar power (CSP) plan
Get PDFThis article deals with the desalination of seawater and brackish water, which can deal with the problem of water scarcity that threatens certain countries in the world; it is now possible to meet the demand for drinking water. Currently, among the various desalination processes, the reverse osmosis technique is the most used. Electrical energy consumption is the most attractive factor in the cost of operating seawater by reverse osmosis in desalination plants. Desalination of water by solar energy can be considered as a very important drinking water alternative. For determining the electrical energy consumption of a single reverse osmosis module, we used the System Advisor Model (SAM) to determine the technical characteristics and costs of a parabolic cylindrical installation and Reverse Osmosis System Analysis (ROSA) to obtain the electrical power of a single reverse osmosis module. The electrical power of a single module is 4101 KW; this is consistent with the manufacturer's data that this power must be between 3900 kW and 4300 KW. Thus, the energy consumption of the system is 4.92 KWh/m3.Thermal power produced by the solar cylindro-parabolic field during the month of May has the maximum that is 208MWth, and the minimum value during the month of April, which equals 6 MWth. Electrical power produced by the plant varied between 47MWe, and 23.8MWe. The maximum energy was generated during the month of July (1900 MWh) with the maximum energy stored (118 MWh)