Current Issue : April - June Volume : 2016 Issue Number : 2 Articles : 6 Articles
A comparative analysis of two mid-sized oxyfuel combustion combined cycles is performed. The two cycles are the semiclosed\noxyfuel combustion combined cycle (SCOC-CC) and the Graz cycle. In addition, a reference cycle was established as the basis for\nthe analysis of the oxyfuel combustion cycles. A parametric study was conducted where the pressure ratio and the turbine entry\ntemperature were varied.The layout and the design of the SCOC-CC are considerably simpler than the Graz cycle while it achieves\nthe same net efficiency as the Graz cycle. The fact that the efficiencies for the two cycles are close to identical differs from previously\nreported work. Earlier studies have reported around a 3%points advantage in efficiency for the Graz cycle, which is attributed to the\nuse of a second bottoming cycle. This additional feature is omitted to make the two cycles more comparable in terms of complexity.\nThe Graz cycle has substantially lower pressure ratio at the optimum efficiency and has much higher power density for the gas\nturbine than both the reference cycle and the SCOC-CC....
Hydropower energy is one of most promising clean energy technologies, however this energy\ntechnology has many challenges. Compared with other renewable energies for example biomass,\nsolar and wind energies, it has high capital investment cost. In Mozambique, access to conversional\nenergy in form of electricity has been limited to most of the rural population. The objectives of\nthe investigation research are to analyze Chua micro-hydropower plant exploration in Manica district\nin Mozambique and to examine the possibility of increasing energy production. The current\ntotal installed power generation capacity in Mozambique is about 939 MW. Hydropower contributes\n561 MW, making a contribution of 61%. Oil contributes 27%, and natural gas contributes 12%\nof the total electric grid generation in Mozambique....
The paper discusses the design, simulation, and optimization of a solar/diesel hybrid power supply system for a remote station.\nThe design involves determination of the station total energy demand as well as obtaining the station solar radiation data. This\ninformation was used to size the components of the hybrid power supply system (HPSS) and to determine its configuration.\nSpecifically, an appropriate software package, HOMER, was used to determine the number of solar panels, deep-cycle batteries,\nand rating of the inverter that comprise the solar section of the HPSS. A suitable diesel generator was also selected for the HPSS\nafter careful technical and cost analysis of those available in the market. The designed system was simulated using the HOMER\nsoftware package and the simulation results were used to carry out the optimization of the system. The final design adequately\nmeets the station energy requirement. Based on a life expectancy of twenty-five years, a cost-benefit analysis of the HPSS was\ncarried out. This analysis shows that the HPSS has a lower cost as compared to a conventional diesel generator power supply, thus\nrecommending the HPSS as a more cost-effective solution for this application....
Cavitation in pumps causes destructive consequences; it must be detected and prevented. The aim\nof the present work is investigating the validity of sound spectrum as a prediction tool for pump\ncavitation. Results showed that; for the discrete frequencies of RF = 47.5 Hz, and BPF = 285 Hz and\nits second, third, and fourth harmonics of 570 Hz, 855 Hz, and 1140 Hz respectively; there are no\ngreat variations in the noise signal for the cavitation and non-cavitation conditions. For the discrete\nfrequency of 147 Hz, there is also no great variation in the noise signal at this frequency. The\nonly apparent result is that; the occurrence of cavitation results high energy noise signals at high\nfrequencies from 1000 Hz to 10000 Hz. The absence of any discrete frequency to be monitored\nmakes the sound spectrum not valid as a prediction tool for cavitation in the pumps....
Multi agent system (MAS) is one of the most dominant research wings which consist of several\nagents who interact with each other to achieve a common objective. MAS has been developed for a\nwide range of applications in power systems. Power system restoration is a main application of\nthat. Researchers present several architectures for fault identification, isolation and restoration of\nthe power system. This paper presents a complete literature review on available architectures for\npower distribution restoration and future trends in MAS based power system restoration....
This paper presents the results of the simulations and their respective analyses corresponding to\nthe power frequency overvoltages resulting from various fault types occurring inside a microgrid.\nDuring the islanded mode of operation, the analysed microgrid can be simultaneously fed by a diesel\ngenerator, a 1 MW wind power turbine, a small solar system and a 1 MW hydroelectric\nscheme. The operating voltage of the microgrid is 2.4 kV. During a fault in the system, the overvoltages\nnormally occur in two remarkable instants. The first one occurs at the beginning of the fault\nitself. The second one occurs at the instant when the fault is cleared. The major concern here is the\novervoltage during the fault period. Due to the travelling wave effect along cables and overhead\nlines composing the microgrid system, these overvoltages can be amplified, thus jeopardizing the\ninsulation level of the microgrid transmission system and related equipment. Much of the work\navailable now is dedicated to overvoltages present in high-voltage systems leaving a gap for the\nstudy and behaviour on low voltage microgrid systems. The overvoltage stress is characterized by\nthe maximum low-frequency, short-duration (crest value) of the overvoltage. Both cables and\noverhead lines that constitute the microgrid transmission system are characterized by their R-L-C\nparameters. The simulations of the microgrid system are conducted using the ATP program. According\nto the international ANSI and IEEE standards, the minimum BIL (Basic Impulse Insulation\nLevel) and BSL (Basic Impulse Switching Level) for the 2.4 kV voltage level are 20 kV and 10 kV,\nrespectively; thus, care should be taken so that the healthy phases upon which commonly appear\nsuch overvoltages are not exceeded in their insulation level....
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