Study on effect of diverse air inlet arrangement on thermal management of cylindrical lithium-ion cells

Lithium-ion cells are preferred in the electrical powertrain due to high-power density, compactness, and modularity. In real driving conditions, the cells undergo discharge rates as high as 4 C resulting in high heat generation affecting the performance. To obtain the maximum performance the pack construction and thermal management of cells are crucial parameters. In our work, air-cooled technique with diverse air inlet and staggered scheme with a two-channel partition approach for thermal management of the cylindrical lithium-ion cells are studied in computational fluid dynamics. The simulation model is validated with experimental results. The obtained results demonstrate that the cells in the dual-directional air inlet arrangement had low maximum temperature difference among and within the cells and required least fan work. This arrangement required least fan work to generate optimal air inlet velocity of 2 m/s for 1, 2, and 3 C and 4 m/s for 4 C discharge rates. There is a reduction of 50% and 33% fan work for 3 and 4 C discharge rates, which are the majority operating points. Also, it shows that the temperature uniformity within the cells has improved. The results of this study can used to optimize parameters for designing an enhanced thermal management system.     

大型喷泵进水流道加工工艺研究

某大型喷泵进水流道线型复杂,加工精度要求高,需综合平衡板件加工、焊接质量及焊接变形控制难度。基于"先大后小、适当余量、便于焊接"的原则进行了板件划分,并采用冷、热弯加工相结合的方法完成板件制作,最终实现流道整体焊接成型,为复杂线型、大尺寸、高强度厚板结构的制作提供了可行的施工经验。     

包钢炼铁厂降低中速磨废料排出量的措施

包钢炼铁厂喷煤系统中速磨废料排出量大,既浪费资源又影响台时产量,近几年一直在摸索如何降低废料排出量。2001年通过改造中速磨喷嘴环,调整系统参数,废料排出量大幅降低。文中对此次改造的措施及效果进行了分析总结。     

入口长度对旋转直通式迷宫气封流场及流场力的影响

迷宫密封的转子和定子部件之间的流场和流场力直接影响转子的振动和稳定性。为了深入了解迷宫密封的流场和流场力特性,选取旋转直通式迷宫气封为研究对象,利用稳态CFD分析方法,研究密封入口长度对旋转直通式迷宫气封泄漏、流场和流场力的影响。考虑和不考虑入口预旋的影响,计算不同入口长度的旋转直通式迷宫气封的泄漏量、流场速度流线、总压强分布、流体压力和流体黏滞力。结果表明:随着入口长度的增大,密封流场泄漏量先增加后减小,转子表面流体压力和流体黏滞力先增加后快速减小;入口长度影响着直通式迷宫气封流场力,存在一个特定的入口长度,使转子表面的流体压力和流体黏滞力最大;当考虑入口预旋时,泄漏量、流体压力和流体黏滞力均有所减小。     

基于语句表和Profibus的水箱液位与进水口流量串级控制系统

提出一种基于语句表和Profibus的水箱液位与进水口流量串级控制方案。给出系统组成和设备硬件组态,说明使用符号地址访问数据块中数据的方法。阐述了PID功能块FB41的使用方法和主要参数说明,给出了语句表主要程序段。相关测试结果表明:该系统响应速度快,超调量小。     

Dynamic delayed detached eddy simulation of a multi‐inlet vortex reactor

The multi‐inlet vortex reactor (MIVR) is used for flash nanoprecipitation to manufacture functional nanoparticles. A validated computational fluid dynamics model is needed for the design, scale‐up, and optimization of the MIVR. Unfortunately, available Reynolds‐averaged Navier‐Stokes methods are unable to accurately model the highly swirling flow in the MIVR. Large‐eddy simulations (LES) are also problematic, as excessively fine grids are required to accurately model this flow. These dilemmas led to the application of the dynamic delayed detached eddy simulation (DDES) method to the MIVR. In the dynamic DDES model, the eddy viscosity has a form similar to the Smagorinsky sub‐grid viscosity in LES, which allows the implementation of a dynamic procedure to determine its model coefficient. Simulation results using the dynamic DDES model are found to match well with experimental data in terms of mean velocity and turbulence intensity, suggesting that the dynamic DDES model is a good option for modeling the turbulent swirling flow in the MIVR. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2570–2578, 2016     

液体中气泡生成影响因素的试验研究

为了提高浆态床反应器内的气含率,提高反应速率,利用高速摄影技术,研究了气泡在液体中形成的特性,在不同气孔内径、不同气体流量下分别考察了平面孔、内伸孔2种进气方式对气泡在水中生成的影响,测算了气泡脱离时的大小及生成所用时间;并考察了内伸孔高度、水温对气泡生成的影响。结果表明:相同试验条件下,生成气泡大小分别随着气孔内径、气体流量的增大而增大,内伸孔进气生成的气泡体积小,用时短,且与内伸孔的内伸高度有关;高温水中气泡生成用时较短,体积较小。     

城市隧道竖井送排式通风优化

为了更有效地发挥送排风竖井在城市隧道中的通风作用,选择合理的送排风组合是一个重要的途径。本文采用CFD方法,对5种排风速度与5种送风速度的25种送排风组合进行了模拟,分析了不同送排风组合隧道内的通风效果。模拟结果表明:当送排比大于1时,隧道内会出现回流,且送排比越大,隧道回流效应越强,经济效益越低。隧道内气流分布和污染物浓度都与送排风组合有关,较大的排风速度虽有利于降低污染物浓度,但能耗也较大,过大或者过小的送风速度都会使隧道局部污染物浓度过高,降低通风作用。因此,综合考虑隧道通风经济性和实用性,确定排风速度为5~6m/s和送风速为8~12m/s为最优组合。选择合理的送排风组合,不仅能有效控制隧道污染物浓度,还能减少能量损失,对城市隧道的建设具有指导意义。     

脱硫用水力旋流器进口压力与浓度对其性能影响的研究

本实验研究了水力旋流器的进口压力与浓度对旋流器性能的影响,包括生产能力、分级效率、分级精度、分级粒度等指标。对于不同的浓度和进口压力对旋流器性能的影响做了定性的分析,研究其变化规律有助于水利旋流器的进一步优化和改进。     

基于CO2稀释的旋流无焰燃烧理论判别方法

基于温度判据和时间判据,本文建立了考虑旋流入口条件和CO₂稀释的无焰燃烧理论判别方法并进行验证,进而讨论了结构参数和操作参数对燃烧模式和火焰稳定性的影响。模型预测的旋流无焰燃烧临界氧浓度与文献中实验数据相比,最大相对误差不超过8%。降低氧浓度、减小当量比或提高入口流量时,温度判据1变化不大,而时间判据更易满足,因此有利于实现无焰燃烧;低旋流数条件下,无焰燃烧稳定性较差。增大燃烧室高度时,温度判据1更易满足,而时间判据更难满足,温度判据1分界线下移更快,有利于形成无焰燃烧;减小燃烧室截面积时,温度判据1变化不大,而时间判据更易满足,有利于实现无焰燃烧;增大燃烧器出口面积时,温度判据1和时间判据均更难满足,且时间判据分界线下移更快,不利于形成无焰燃烧。