The emerging solar vapor generation technology is becoming one of the most promising solar photothermal conversion technologies, which could relieve fresh water shortage.

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Developing redox electrolytes with high thermopower is the key to making efficient thermogalvanic batteries for harvesting low‐grade heat. This work applies molecular dynamics simulations to predict the thermopower (i.e. thermogalvanic temperature coefficient) of the redox pairs Fe(CN)63−/Fe(CN)64− and Fe3+/Fe2+, showing excellent agreement with experimental values. We showed that of the Fe3+/Fe2+ redox pair can be increased from 1.70.4 mV/K to 3.80.5 mV/K with the increased acetone to water fraction. We discovered a significant change in the variance of solvent dipole orientation between Fe3+ and Fe2+, which can serve as a microscopic indicator for large . In mixed acetone‐water solvent, of Fe3+/Fe2+ showed a rapid increase at high acetone fractions, due to the intercalation of acetone molecules into the first solvation shell of the Fe2+ at high acetone fractions. Our discovery provides insights into how solvation shell order can be engineered to develop electrolytes with high .image

Downsizing is an effective way to improve the fuel economy of an engine and to reduce the emissions. For turbocharged engines, further downsizing or increasing the power density requires air to be compressed to a higher pressure. However, conventional compressors have a narrow stable operating range at high pressure ratios and cannot provide such highly pressurized air for ultra-high-power-density engines. Thus, a variable inlet prewhirl is employed to extend the stable operating range of the compressor. This paper investigates the performance of a centrifugal compressor with different prewhirls and speeds, quantitatively estimates the potential of range extension with a variable inlet prewhirl and discusses the mechanisms thought to be responsible for the range extension. The approach combines steady threedimensional Reynolds-averaged Navier-Stokes simulations with theoretical analysis. In order to make the study universal to various applications with a inlet prewhirl, the inlet prewhirl was generated by giving a velocity direction at the inlet boundary of the numerical method. A variable inlet prewhirl from 0°to 60°improves the stable operating range from 23.5% to 49.0% at a pressure ratio of 4.8. The extended range is based on the shifts in the choke line and the surge line with a positive inlet prewhirl. The decreased choking flow with a positive inlet prewhirl is mainly caused by the drop in the work input from the impeller. The dominant factor in reducing the surge flow of compressor is the highly increased stability of the impeller. It is also found that the impeller tends to choke and the diffuser tends to surge with increasing prewhirl. By extending the stable operating range of the compressor with a variable inlet prewhirl from 0°to 60°, the improvement in the maximum pressure for turbocharged engine is about 64% and the increase in the brake torque is estimated to be up to 42%.

Polypropylene/poly(butylene terephthalate) (PP/PBT) microfibrillar composites (MFCs) were prepared through in situ one‐step direct extrusion using a triangle‐arrayed triple‐screw extruder (TTSE) at a processing temperature between the melting points of two components. The orthogonal experimental method was designed to assess the effects of the PBT content and processing parameters (temperature, screw speed, and feed rate) on the morphology of PBT fibrils. It can be found that the most important influence factor on the fibril formation is the PBT content, followed by temperature, feed rate, and screw speed. Furthermore, the morphological evolution procedures of the dispersed phase started from spherical pellets to ellipsoids or ribbons, forming short fibrils, and consequently high‐aspect‐ratio fibrils appeared under the alternating shear‐extensional flow field. Moreover, the rheological properties of linear PP incorporating fibrillated PBT were thoroughly investigated. The relaxation time of blends with various fibrous PBT was linearly proportional to the aspect ratio of fibrils. Strain‐hardening in extensional flow was observed for blends with long fibrils, and the strain‐hardening factor grew with the fibrillar aspect ratio, indicating the formation of a physical entanglement network between fibrils and matrix. POLYM. ENG. SCI., 58:1166–1173, 2018. © 2017 Society of Plastics Engineers

Summary A solar vapor generation system with a high evaporation efficiency and also a high mechanical strength is still attractive, while most previous works only focused on efficiency. Herein, we firstly prepared a carbon‐black/wood‐flour system with strength enhanced by polystyrene. Then, we investigated the effects of porosity, polystyrene content, and thermal insulation on the evaporation performance of the system. Experimental results indicate that the porosity of system can significantly affect the evaporation efficiency. With the increase of porosity, there exists an optimal porosity to obtain a high evaporation efficiency. A higher content of polystyrene, which could cause a lower thermal conductivity of the system, always gives a higher evaporation efficiency when the porosity is fixed. For polystyrene content of 60 wt% and system porosity of 36%, under a 1‐sun irradiation, there is an optimal evaporation efficiency of about 80.4%. Additionally, the fracture stresses of the system in dry and wet states could be as high as 2.18 and 2.03 MPa, respectively, which ensures the system strength. Considering the high efficiency, high mechanical strength, low cost, and easy preparation, this system has a good potential to be used in practical applications.

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