Piezoelectric nanogenerators (PENGs) with good flexibility and high outputs have promising applications in harvesting mechanical energy and powering electronics. In this study, a synthesis of hierarchical BaTiO3 flowers (BTFs) and their filling into the polydimethylsiloxane (PDMS) matrix to obtain composites with excellent energy harvesting properties is reported. The BTF‐based PENG possesses a voltage of 260 V, a current of 50 µA, and a power of 1728 µW under a compression of 50 N at 3.5 Hz, which output power is two orders higher than that of polymer composites filled with BT nanoparticles. Simulation indicates that the high local stress at petals of BTFs is the main reason for the enhanced performances. The PENG shows good durability under 5000 cycles and lights up 58 commercial light emitting diodes and a display. The PENG generates 30–100 V in harvesting human motions of hand slapping and foot stepping and ≈50 V in harvesting the sport kinetic energy of basketball bouncing. This research presents a BTF‐based PENG with significantly enhanced energy harvesting performances for applications in micro/nanoenergy systems.

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Abstract:An accurate prediction of tray hydraulics is very important for large diameter trays design, and vapor cross-flow channeling is one of the key points that affect the hydraulics calculation.Therefore, in this article, a theoretical analysis was first conducted to reveal that the energy of gas-liquid on the tray was closely related to its flow state. Then, a model was obtained on the basis of the principle of the lowest energy, which can be used to calculate vapor cross-flow channeling.The model shows that the ratio of dry tray pressure drop to liquid height on a tray determines the gas distribution on the tray. Finally, the model was tested by comparisons with experimental results available in reference. The agreements are good. Furthermore, the effects of liquid load and fractional hole area on vapor cross-flow channeling were studied. The results are consistent with the field experience summarized in literatures.

The recovery of gasoline vapor is still a major challenge in the petrochemical industry. In this study, a zeolitic imidazolate frameworks (ZIFs) membrane has been developed and first applied to gasoline vapor recovery. Zeolitic imidazole framework (ZIF-8) membranes were fabricated by a facile solvothermal seed growth method on ZrO 2 supports. X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis measurements were conducted to study the morphologies, structure, and physical and chemical properties of ZIF-8 membranes. The effects of trans-membrane pressure drop, operating temperature, feed concentration, and stage cut on the separation performances of ZIF-8 membranes were systematically investigated. At 293 K, the ZIF-8 membrane showed an optimum n-hexane (n-C 6 H 14 ) permeance of 7.16 × 10 −8 mol/(m 2 ·s·Pa) with the corresponding separation factor of 2.46 for the nitrogen/n-hexane model mixtures at a trans-membrane pressure drop of 0.05 MPa, a stage cut of 0.293, and a n-hexane volume fraction of 30%. Moreover, the separation factor for the multicomponent alkanes decreased with increasing the number of n-alkanes because of competitive adsorption of the n-alkanes in membrane pores. Experimental results indicated that the ZIF-8 membrane is a fairly promising candidate for the application in gasoline vapor recovery.