In this paper, the concept of built-in transformer voltage doubler cell is derived to generate an improved interleaved high step-up converter for distributed photovoltaic generation applications. The proposed built-in transformer voltage doubler cell is composed of three transformer windings, two voltage doubler diodes, and two voltage doubler capacitors. The voltage doubler capacitors are charged and discharged alternatively to double the voltage gain. The switch duty cycle and the transformer turns ratio can be employed as two controllable freedoms to lift the voltage ratio flexibly. The power device voltage stress can also be reduced to improve the circuit performance. Furthermore, the active clamp scheme is adopted to recycle the leakage energy, absorb the switch turn-off voltage spikes, and achieve zero-voltage switching (ZVS) operation for all active switches. Meanwhile, the diode reverserecovery problem is alleviated by the leakage inductance of the built-in transformer. All these factors benefit the circuit performance improvements in the high step-up and large current applications. Finally, a 1-kW prototype with 40-380 V conversion is built and tested to demonstrate the effectiveness of the proposed converter.Index Terms-Active-clamp scheme, built-in transformer voltage doubler cell, high step-up, interleaved boost converter.

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Metal selenides, such as NiSe2, have exhibited great potentials as multifunctional materials for energy storage and conversation. However, the utilization of pure NiSe2 as electrode materials is limited by its poor cycling stability, low electrical conductivity, and insufficient electrochemically active sites. To remedy these defects, herein, a novel NiSe2/Ti3C2Tx hybrid with strong interfacial interaction and electrical properties is fabricated, by wrapping NiSe2 octahedral crystal with ultrathin Ti3C2Tx MXene nanosheet. The NiSe2/Ti3C2Tx hybrid exhibits excellent electrochemical performance, with a high specific capacitance of 531.2 F g−1 at 1 A g−1 for supercapacitor, low overpotential of 200 mV at 10 mA g−1, and small Tafel slope of 37.7 mV dec−1 for hydrogen evolution reaction (HER). Furthermore, greater cycling stabilities for NiSe2/Ti3C2Tx hybrid in both supercapacitor and HER have also been achieved. These significant improvements compared with unmodified NiSe2 should be owing to the strong interfacial interaction between NiSe2 octahedral crystal and Ti3C2Tx MXene, which provides enhanced conductivity, fast charge transfer as well as abundant active sites, and highlight the promising potentials in combinations of MXene with metal selenides for multifunctional applications such as energy storage and conversion.

Extractive distillation is one of the most attractive approaches for separating azeotropic mixtures. Few contributions have been reported to design an extractive distillation for separating maximum-boiling azeotropes and no systematic approaches for entrainer screening have been presented. A systematic approach to design of two-column extractive distillation for separating azeotropes with heavy entrainers has been proposed. A thermodynamic feasibility analysis for azeotropes with potential heavy entrainers was first conducted. Then, five important properties are selected for entrainer evaluation. Fuzzy logic and develop membership functions to calculate attribute values of selected properties have been used. An overall indicator for entrainer evaluation is proposed and a ranking list is generated. Finally, the top five entrainers from the ranking list have been selected and use process optimization techniques to further evaluate selected entrainers and generate an optimal design. The capability of the proposed method is illustrated using the separation of acetone-chloroform azeotropes with five potential entrainers.