Performance analysis of two combined cycle power plants with different steam injection system design

A thermal analysis of two combined cycle power plants is performed. The steam injection system in the combustion chamber constitutes the main difference between the two designs. For the first power plant (design 1) the injected steam is generated in the HRSG. While for second power plant (design 2) this steam is provided using a heat recovery system installed at the compressor outlet. The steam turbine cycle engenders two pressure extraction levels connected to open feed-water heaters. The steam injection in the combustion chamber improves the overall combined cycle efficiency if this steam is generated outside the HRSG.The increase of the ambient temperature affects the overall cycle efficiency.The optimum thermal efficiency, for any temperature value during the year, may be obtained for suitable margin of steam injection ratio. The second design presents better overall efficiency then the first one. In winter season (T_am = 15 °C), the overall cycle efficiency is about 54.45% for a range of steam injection ratio within 11.8 and 14%. While in summer season (T_am = 35 °C) and for the same cycle efficiency, the required range of steam injection ratio is between 18.5 and 18.8%.     

Energy management of PEM fuel cell/ supercapacitor hybrid power sources for an electric vehicle

This paper presents the utilization of a supercapacitor (SC) as an auxiliary power source in an electric vehicle (EV), composed of a proton electrolyte membrane fuel cell (PEMFC) as the main energy source. The main weak point of PEMFC is slow dynamics because one must limit the fuel cell current slope in order to prevent fuel starvation problems, to improve its performance and lifetime. The very fast power response and high specific power of a supercapacitor can complement the slower power output of the main source to produce the compatibility and performance characteristics needed in a propulsion system. DC-DC converters connected to the hybrid source ensure a constant voltage value in inverters inputs. After an architecture presentation of the hybrid energy source, two parallel-type configurations are explored in more detail. For each of them, the energy flow control and management, validated simulation shows the performance obtained in this configuration. The hybrid source management is based primarily on the intervention of the supercapacitor in fugitives' schemes such as slopes, different speeds and rapid acceleration. Secondly, the PEMFC intervenes to guarantee the power in permanent regime. Finally, simulation results considering energy management are presented and illustrated the hybrid energy source benefits.     

Treatment of Algerian crude oil using REB09305 OS demulsifier

Algerian crude oil was submitted to a treatment procedure using REB09305 OS demulsifier. Temperature, time of contact with charge and centrifugation speed were studied. Separation of water from crude oil was observed with a demulsification ratio of 100% in ambient temperature for 20?ppm demulsifier dose, 1200?rpm and 45?min of centrifugation time. The results obtained in this study showed that REB09305 OS demulsifier can be considered a promising product for the treatment of industrial crude oil and the removal of water from it.     

Mutual information statistics for dual MIMO systems in correlated Rayleigh fading

In this letter, we derive very simple and exact expressions for the mutual information (MI) distributions under isotropic Gaussian input of dual multiple-input multiple-output (MIMO) systems, where the minimum number of antennas at either side of the wireless link is two, in a semicorrelated Rayleigh fading environment with correlation at the dual-antenna side only. Furthermore, exact closed-form expressions for the MI moments (mean, variance), and other higher order statistics, such as the skewness and kurtosis, are derived. The proposed methodology for evaluating the MI statistics, is easily extendable to other multielement antenna settings such as single-input multiple-output (SIMO), multiple-input single-output (MISO) and dual MIMO systems for both uncorrelated and semicorrelated Rayleigh fading, where correlation can be assumed at the side with the largest number of antennas.     

AC actuation contribution to the induced electromotive force in the miniaturized inductive planar microphone

In this paper, we aim to analyze the gain ratio in the output induced voltage of a CMOS-compatible miniaturized electrodynamic microphone which is based on the use of two coplanar concentric inductors. These latter are comparable to a concentric transformer with a secondary situated on the microphone diaphragm top. The study has been applied when the outer inductor is actuated using an AC bias instead of DC leading to a time-variable B-field. The induced output voltage expression has been evaluated using two distinct analytic methods: the magnetic field derivation and the electric field approach. When an AC current with frequency above that of the acoustic band is used to bias the primary, results show that the induced voltage increases and becomes independent from the incident pressure wave frequency. The paper demonstrates also that with an AC bias, the microphone induced voltage values can reach the order of hundreds of µVs, as opposed to only few µVs when applying a DC bias. The gain in the induced voltage has been investigated and it is shown that it can be correlated to the AC current frequency, ω_c, and the inner inductor fluctuation frequency, ω_p. Moreover, this has been quantified analytically and it is shown that it equals ω_c/8ω_p. This result will not only enhance the overall performance of the microphone, but will also make the preamplification design less complicated by increasing the SNR ratio.     

Reduction of Power Fluctuation in ECMA-368 Ultra Wideband Communication Systems Using Multilayer Perceptron Neural Networks

ECMA-368 Ultra Wideband (UWB) wireless communication Standard adopts Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) technology to transmit information with high data rate (480 Mbits/s). However, the high Peak to Average Power Ratio of MB-OFDM UWB signals, limits the power efficiency of the high power amplifier due to nonlinear distortion. In order to avoid this drawback, an efficient scheme based on multilayer perceptron, artificial neural networks is proposed. The neural network is adjusted by using active constellation extension technique which provides satisfactory results. This proposed solution gives good performance compared to previously available methods with much lower complexity, without iterations, good bit error rate and no increase in transmitted signal power and bandwidth.     

Exact expression for the BER of rectangular QAM with arbitrary constellation mapping

The exact closed-form expression for the bit-error rate (BER) of rectangular quadrature amplitude modulation (QAM) is given. The presented formula is independent of the bit mapping and it is thus particularly useful in the design and analysis of modulation schemes employing non-Gray mapping. Compared with the so-called expurgated bound and the union bound, our expression is shown to accurately predict the BER in the low signal-to-noise ratio range where the bounding techniques fail.