钢制导热油烘缸的数值模拟与结构优化

针对钢制导热油烘缸在工作时出现工作表面温度分布不均匀、温差大等情况，采用三维建模和模拟仿真方法对钢制导热油烘缸的结构进行优化。本研究主要从3个方面对钢制导热油烘缸进行结构改进，分别是改变循环油路通道数量，改变进油槽与出油槽上孔的排列方式，改变循环油路的结构。研究结果表明，相对其他烘缸结构，具有循环油路通道数量为20个、进油槽与出油槽上孔为单排排列、循环油路两两相通的钢制导热油烘缸的性能更好，可以达到工作表面温度分布均匀、温差控制在±5℃以内的目的。     

Understanding consumer resistance to the consumption of organic food. A study of ethical consumption,purchasing, and choice behaviour

Although the demand for organic food is growing globally, the mainstream consumption of organic food is far less. The present study attempts to understand the underlying reasons for consumer resistance toward consuming organic food using the theoretical framework of innovation resistance theory (IRT). The study further examines the association between different consumer barriers and purchase decisions (purchase intentions, ethical consumption intentions, and choice behaviour) at different levels of buying involvement and environmental concerns. The collected data, consisting of 452 consumers, were analyzed by structural equation modeling approach. The results showed that value barrier shared a negative association with purchase intentions and ethical consumption intentions. Ethical consumption and purchase intention were found to have a direct influence on choice behaviour. Additionally, the relationship between ethical consumption intention and choice behaviour is mediated by purchase intention. However, no significant differences have emerged based on the level of buying involvement and environment concerns. The findings of the study provide insight into public policymakers, marketers, suppliers, and consumer associations by enhancing their current understanding of buying behaviour of the growing organic food community.     

Structure variation and energy storage properties of acceptor-modified PBLZST antiferroelectric ceramics

Energy storage capacitors with high recoverable energy density and efficiency are greatly desired in pulse power system. In this study, the energy density and efficiency were enhanced in Mn-modified (Pb_0.93Ba_0.04La_0.02)(Zr_0.65Sn_0.3Ti_0.05)O₃ antiferroelectric ceramics via a conventional solid-state reaction process. The improvement was attributed to the change in the antiferroelectric-to-ferroelectric phase transition electric field (E_F) and the ferroelectric-to-antiferroelectric phase transition electric field (E_A) with a small Mn addition. Mn ions as acceptors, which gave rise to the structure variation, significantly influenced the microstructures, dielectric properties and energy storage performance of the antiferroelectric ceramics. A maximum recoverable energy density of 2.64 J/cm³ with an efficiency of 73% was achieved when x = 0.005, which was 40% higher than that (1.84 J/cm³, 68%) of the pure ceramic counterparts. The results demonstrate that the acceptor modification is an effective way to improve the energy storage density and efficiency of antiferroelectric ceramics by inducing a structure variation and the (Pb_0.93Ba_0.04La_0.02)(Zr_0.65Sn_0.3Ti_0.05)O₃-xMn₂O₃ antiferroelectric ceramics are a promising energy storage material with high-power density.     

Reviews of clean coal conversion technology in China:Situations & challenges

It is important to develop the advanced coal to chemicals industry (ACCI) against a backdrop of coal-based energy structures,excessive imported oil and natural gas,and strict environmental con-straints in China.In this study,the technology and industry of China's ACCI are reviewed to explain the effect of using coal to replace oil and natural gas,and the corresponding resource and environmental burdens that this will create.Development trends in technology and industry are also proposed to explore future scenarios.The review shows that although excellent progress has been made on an indus-trial scale,demonstrative level,and in terms of technology and equipment,the lack of strategic under-standing,severe external constraints,partly underdeveloped technologies,and weak foundations must be immediately addressed.Therefore,it is necessary to clarify the importance that the ACCI has on the energy revolution and energy system.Based on technological innovation,a variety of external factors should be considered as a whole with emphasis on filling the knowledge gap of theoretical foundations and industry standards to support high-quality development for ACCI.     

接触器触头系统振动机理分析及算法优化

为了解决合闸过程中动、静触头接触引起的振动弹跳问题.本文建立了接触系统的二自由度运动微分方程,并利用遗传算法对交流接触器吸合过程进行优化,同时通过高速摄影实验对接触弹跳的全过程进行了观察和分析.结果表明:理论与实验结果高度一致,铁心在触头分离前发生碰撞,进一步加剧触头弹跳;铁芯弹跳再次碰撞时,触头的弹跳不受影响;在接触器运行过程中,动铁芯的运动会引起系统轻微振动;采用遗传算法优化的接触器触头弹跳时间和最大振幅均减小.研究结果为进一步控制和减小接触弹跳提供了理论依据.     

Pore-scale study of effects of different Pt loading reduction schemes on reactive transport processes in catalyst layers of proton exchange membrane fuel cells

Reducing the Platinum (Pt) loading while maintaining the performance is highly desired for promoting the commercial use of proton exchange membrane fuel cells (PEMFCs). Different methods have been adopted to fabricate catalyst layers (CLs) with low Pt loading, including utilizing lower Pt/C catalysts (MA), mixing high Pt/C catalysts with bare carbon black particles (MB), and reducing CL thickness while maintaining high Pt/C ratio (MC). In this study, self-developed pore-scale model is adopted to investigate the performance of the three Pt reduction methods. It is found that MA shows the best performance while MB shows the worst. Then, effects of Pt dispersion are further explored. The results show that denser Pt sites will result in higher local oxygen flux and thus higher local transport resistance. Therefore, MA method, which shows the better Pt dispersion, leads to improved performance. Third, CLs with quasi-realistic structures are investigated. Higher tortuosity resulting from the random pores produces higher bulk resistance along the thickness direction, while MA still exhibits the best performance. Finally, improved CL structures are investigated by designing perforated CL structures. It is found that adding perforations can significantly reduce the bulk transport resistance and can improve the CL performance. It is demonstrated that CL structure plays important roles on performance, and there are still huge potentials to further improve CL performance by increasing Pt dispersion and optimizing CL structures.     

Plasmonic semiconductor: A tunable non-metal photocatalyst

Doped semiconductor, a newly discovered plasmonic nanomaterial, has attracted tremendous interest due to its tunable properties. In the field of photocatalysis, the perfect combination of metal-like and semiconductor properties makes it the replacement and supplement of metal plasmonic nanomaterials. This new plasmonic photocatalysis offers high conversion efficiencies and wide optical absorption range with low fabrication costs. This article reviews the recent developments and achievements by which the localized surface plasmon resonance (LSPR) in non-metal plasmonic nanomaterial for photocatalytic applications, including pure non-metal plasmonic photocatalysts and various enhancement strategies such as doping, co-catalyst, heterojunction, LSPR coupling and upconversion luminescence enhancement. It broadens the horizons for plasmonics in the study of photocatalysis and even in energy-related applications.     

A machine learning‐based operational control framework for reducing energy consumption of an amine‐based gas sweetening process

This study proposes a data‐driven operational control framework using machine learning‐based predictive modeling with the aim of decreasing the energy consumption of a natural gas sweetening process. This multi‐stage framework is composed of the following steps: (a) a clustering algorithm based on Density‐Based Spatial Clustering of Applications with Noise methodology is implemented to characterize the sampling space of all possible states of the operation and to determine the operational modes of the gas sweetening unit, (b) the lowest steam consumption of each operational mode is selected as a reference for operational control of the gas sweetening process, and (c) a number of high‐accuracy regression models are developed using the Gradient Boosting Machines algorithm for predicting the controlled parameters and output variables. This framework presents an operational control strategy that provides actionable insights about the energy performance of the current operations of the unit and also suggests the potential of energy saving for gas treating plant operators. The ultimate goal is to leverage this data‐driven strategy in order to identify the achievable energy conservation opportunity in such plants. The dataset for this research study consists of 29 817 records that were sampled over the course of 3 years from a gas train in the South Pars Gas Complex. Furthermore, our offline analysis demonstrates that there is a potential of 8% energy saving, equivalent to 5 760 000 Nm³ of natural gas consumption reduction, which can be achieved by mapping the steam consumption states of the unit to the best energy performances predicted by the proposed framework.