This paper utilizes a statistical approach, the response surface optimization methodology, to determine the optimum conditions for the Acid Black 172 dye removal efficiency from aqueous solution by electrocoagulation. The experimental parameters investigated were initial pH: 4–10; initial dye concentration: 0–600 mg/L; applied current: 0.5-3.5 A and reaction time: 3–15 min. These parameters were changed at five levels according to the central composite design to evaluate their effects on decolorization through analysis of variance. High R2 value of 94.48% shows a high correlation between the experimental and predicted values and expresses that the second-order regression model is acceptable for Acid Black 172 dye removal efficiency. It was also found that some interactions and squares influenced the electrocoagulation performance as well as the selected parameters. Optimum dye removal efficiency of 90.4% was observed experimentally at initial pH of 7, initial dye concentration of 300 mg/L, applied current of 2 A and reaction time of 9.16 min, which is close to model predicted (90%) result.
A soft-switched dual-boost coupled-inductor-based converter is proposed which possesses an intrinsic advantage, in terms of transferring the energy directly to output to provide the essential voltage and power for load. The fabulous characteristic of the proposed structure, the combination of forward and flyback converter, makes it possible to utilise one magnetic core for two coupled inductors, advancing the power density. Another implication of proposed converter is the fact that leakage inductances pave the way for the zero-current-switching implementation by confining the diodes current slope during turn-off period. As regards the voltage conversion ratio, the secondary windings of the coupled inductors operate in series with the capacitors of both voltage-doubler stage and capacitordiode stages; consequently, designer is under no obligation to use coupled inductors with extreme turn ratio. Concerning the mentioned features of converter besides its high-efficiency power conversion over a broad range of input voltage, the proposed structure is well suited for the purpose of high step-up dc-dc converter. Lastly, the results of laboratory prototype, working with switching frequency of 50 kHz and output voltage 380 V, are convincingly in line with the mathematical analysis.
Fuel cells are used as a power generator in distributed generation and aircrafts applications. This paper proposes a new high step-up DC-DC converter with zero-voltage switching (ZVS) of switches and zero current switching (ZCS) of diodes, to be used as fuel cell's power conditioner. To have a ripple free input current, a coupled inductor can be used at the input side of the converter. The voltage gain of the converter is calculated and required conditions for soft switching have been presented. The voltage stress of elements of the proposed converter is discussed, the efficiency of converter is derived and finally experimental results have been used to validate the properties of the converter.
A high voltage gain dual interleaved full bridge converter with Zero Voltage Switching (ZVS), improved integrated magnetics, and a new resonant Switched-Capacitor-Cell (RSC) is presented. By taking the advantage of a new resonant switched capacitor cell and transformers with low turn-ratio as well as low leakage inductances, the desired high output voltage can be obtained. Furthermore, the output diodes operate in Zero Current Switching (ZCS) condition, and switches are maintained under ZVS condition over the whole range of output load variations. In addition, switches turn off near zero current leading to high overall efficiency. An interleaved approach (multi-cell) is adopted over a single cell to increase the power handling capacity. Furthermore, transformers of dual cells are integrated into a single UU core which cuts down the total volume of the converter as well as the total core loss. Since secondary windings have opposite polarities, there exists no DC flux, and the top and bottom RSC cells operate in 180 degree out of phase. Taking the aforementioned characteristics into consideration, the proposed converter has a good performance for high voltage applications. Experimental results of a 3 kw prototype with an output voltage of 16 kV validate the features of this topology.
The aim of this research is improvement of the Taguchi design optimization using artificial neural network (ANN) and genetic algorithm (GA) in Acid Orange 7, Acid Brown 14, and Acid Red 18 azo dyes removal by electrocoagulation. For this purpose, 27 tests were undertaken for investigation of five parameters including current density, reaction time, initial dye concentration, dye type, and initial pH by using Taguchi's orthogonal array. Additionally, according to analysis of variance, dye type and reaction time were the most important parameters for responses of dye removal efficiency and operating costs in Taguchi design, respectively. Prediction and modeling of the dye removal efficiency response were also accomplished by ANN. High R 2 values (97%) indicated that the accuracy of the Taguchi and ANN models are acceptable. In addition, ANN was used in GA for finding the best elimination conditions for the selected dyes according to the Taguchi design. Dye removal efficiencies of 96.79%, 98.12%, and 76.47% were reported for Acid Orange 7, Acid Brown 14, and Acid Red 18, respectively, in the ANN model at the best elimination conditions.
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