Influence of high energy ball milling on structural,microstructural and optical properties of TiO2 nanoparticles

The influence of high-energy ball milling on structural, microstructural, and optical properties of TiO₂ by modifying the nanoparticle size was studied. Five samples were extracted at different milling times (0, 2, 4, 8, and 13 h). The average particle sizes estimated by dynamic light scattering (DLS) were 205, 155.8, 116.8, 82.9, and 82.7 nm at 0, 2, 4, 8, and 13 h, respectively. X-ray diffraction analysis confirmed progressive broadening of the peaks as the milling time elapsed. Besides, a correlation was found between d spacing and the average crystal size. The UV–Vis diffuse reflectance spectra of TiO₂ revealed a decrease in reflectance due to particle size reduction. Similarly, an alteration of the bandgap transition energy was presented, whose values gradually decreased from 2.966 eV to 2.861 eV for the sample without and with the maximum duration milling performed (13 h), respectively. Likewise, the SEM analysis showed a distribution in nanoparticle size that became more homogeneous and smaller average grain size as the milling duration was longer.     

煤矿水仓清理新工艺

通过调研现场情况以及检测煤泥特性，探寻一种实用性强、方法简单的新工艺来替代劳累的人工和繁琐的机械清淤，解决现实问题。针对实际情况开发清仓新工艺，介绍了该工艺的技术路线选择、设计依据以及实际应用效果。该新工艺具有降低清仓时间、减轻工人劳动强度、设备操作简单、实用性强等特点。     

抑霜型空气源热泵机组应用实测研究

空气源热泵结霜过程会恶化机组的实际运行性能，重霜工况下尤为严重，发展抑霜型空气源热泵是保障其高效适用和良性发展的关键。本文依托四川省康定市的某住宅示范工程，开展抑霜型空气源热泵和常规型空气源热泵的现场实测研究，研究抑霜型空气源热泵实际应用中的抑霜、制热性能表现，并进行技术经济性分析。结果表明：抑霜型空气源热泵抑霜效果显著，制热性能得到显著改善，能效提升达到21%~37.3%，费用年值比常规空气源热泵降低了13%，1年左右即可回收追加的投资，具有更好的技术经济性，有助于空气源热泵技术在严重结霜气候区域的高效应用。     

Physical and electrochemical behavior of affordable Na3SbS4 solid electrolyte at different heat treatment temperatures

High-capacity and affordable all-solid-state Na-ion batteries have gathered increasing interest in recent years owing to low-cost sodium, which contributes to reducing the price of these Na-ion batteries to approximately 70% of that in lithium batteries. However, in terms of electrolyte performance and battery cost, the complete replacement of lithium batteries has a long way to go. In this work, low-cost and high-safety Na₂S·9H₂O materials are used in synthesizing Na₃SbS₄ solid electrolyte, the price of which is only one-fifth that of high-purity Na₂S. The structure and electrochemical properties are studied through X-ray diffraction analysis, Raman spectroscopy, scanning electron microscopy, and electrochemical tests. Results indicate that a multiphase Na₃SbS₄ structure containing cubic and tetragonal phases formed after heat treatment at 300 °C. In addition, a third phase transition of Na₃SbS₄ is inferred after further heating at 600 °C. This phase structure contributes to the improvement of electrochemical performance by promoting increasing ionic conductivity to 0.54 mS cm^?1 at room temperature (25 °C) and reducing activation energy to 0.076 eV. This work provides an affordable material with good electrochemical properties and not only simplifies the preparation but also greatly reduces the risk of the process.     

车用有机朗肯循环系统中计量泵的性能研究

在模拟车用有机朗肯循环(organic Rankine cycle,ORC)系统的工作环境下,设计并搭建以R123作为工质的液压隔膜计量泵性能测试平台。在额定转速(2900 r/min)下,通过调节液压隔膜计量泵的冲程(25%、50%、75%、100%)和出口压力,得到变工况下液压隔膜计量泵的特性曲线,并分析液压隔膜计量泵的关键参数对车用ORC系统性能的影响情况。结果表明:液压隔膜计量泵的流量受冲程影响,与出口压力基本无关。其输入功率和实际运行效率均随着冲程的增加而升高,最高分别可达523.91 W、88.27%。应用该液压隔膜计量泵的模拟车用ORC系统吸热量变化范围较广,系统热效率最高可达12.81%。液压隔膜计量泵可应用于车用ORC系统,通过调节液压隔膜计量泵的冲程和出口压力,可实现提高车用ORC系统热效率、增加系统净输出功率的目的。     

溢流型球磨机进料口密封装置的改进

分析了溢流型球磨机进料口矿浆泄漏的原因以及泄漏后给球磨机润滑系统和环境所带来的危害。通过对溢流型球磨机进料口密封装置的改进,减少和杜绝了矿浆泄漏,改善了球磨机运行环境,延长了润滑油使用周期、提高了球磨机有效作业率,降低了球磨机运行成本。     

大斜度井段低沉没度工况排采泵阀动力学特性

目前对于煤系地层天然气井所配套有杆泵泵阀动力特性的研究,主要是移植和借鉴常规油气井抽油泵泵阀的分析方法,多针对油气井开采较高的沉没度,并没有考虑低沉没度和大斜度工况下的泵阀动力学和水力摩阻等参数的影响,也没有揭示水平井泵阀顺利开启所需要的具体条件。为此,综合考虑低沉没度和大斜度等因素耦合的影响,推导造斜段泵阀随井液运动微分方程组,建立有杆泵井液流经泵阀阀隙水力摩阻数学模型,基于数值模拟的方法研究了水平井泵阀动力学、水力摩阻与临界沉没度。研究结果表明:①低沉没度和大斜度耦合作用下,增大冲程和冲次会提高造斜段泵阀阀球的升程、速度和加速度,缩短加速度趋向平缓所用的时间,并且水平井泵阀开启瞬间阀球会出现短暂的周期性波动;②受弹簧力与阀球重力的双重作用,水平井有杆泵的临界沉没度明显低于直井工况且固定阀球伴随弹簧快速复位,这有利于顺利开启水平井的游动阀球和固定阀球并提高泵效;③增大冲程、冲次和泵径会使水平井有杆泵井液流经泵阀水力摩阻及其临界沉没度变大,并且增大冲程更有利于提高低流速井液入泵流速,但同时也会显著地提高临界沉没度。结论认为,该研究成果对于保障煤系地层天然气井连续稳定排采和提高有杆泵的可靠性都具有重要的参考意义。     

汽蚀对离心泵性能影响的实验研究

离心泵长时间运转后,会出现危害严重的汽蚀现象,造成泵性能下降,严重时影响泵的效率、寿命,甚至造成离心泵内部部件损坏。文章通过改变进口压力的方法对单泵、双泵并联、双泵串联等工况下汽蚀对离心泵性能影响进行实验研究。结果表明:当进口压力小于输送液体的饱和蒸汽压时,液体开始发生气化并伴随气泡产生,表明泵内发生汽蚀;汽蚀初期离心泵的效率开始下降,但表现不明显;随着汽蚀不断增大至严重汽蚀区时,Q 1~η曲线出现陡坡,效率出现明显下降并伴随嗡响。实验证明采用提高泵的进口压力等措施可适当减小汽蚀对泵性能的不利影响。     

不同流量下高速离心泵压力脉动特性分析

为掌握高速离心泵内压力脉动变化规律及其脉动源,采用CFX软件对其内部流场进行数值模拟,分析其不同监测点在0.4Qd~1.2Qd(设计流量)的压力脉动特性。研究表明:蜗壳与隔舌的动静干扰是主要的压力脉动源,且在叶轮出口处压力波动幅值最大,其主要频率为叶片通过频率;吸力面的压力要比压力面小,压力面在叶频附近的波动变化区域较大;流量在0.6Qd及以下时,整体压力幅值变化较其他流量时更为剧烈;压力脉动沿流道方向向下游扩散段传递,在蜗壳出口处压力值最小;大流量下的流线较为平滑,而小流量下流线变得紊乱,流量越小流线的扭曲就越严重。     

Preparation of YSZ porous ceramics with precise porosity control

Conventional preparation of porous ceramics often hard to accurately control the porosity of the samples. In this paper, by improving the foaming method, the foaming process is placed in the limited space of the ball mill tank, and YSZ porous ceramics with different porosity are obtained by changing the amount of slurry. Initial results showed that the porosity of the sample varies linearly with the increasing of addition of slurry. From the microscopic morphology, it can be seen that the increase in slurry content will reduce the number of pore with little changed size, which lead to the decrease in porosity. Therefore, with simple calculation YSZ porous ceramics with 85%, 80%, 75%, 70%, and 65% porosity can be obtained using the method of foaming in limited space by ball milling.