Numerical investigation of a multichannel reactor for syngas production by methanol steam reforming at various operating conditions

A novel multichannel reactor with a bifurcation inlet manifold, a rectangular outlet manifold, and sixteen parallel minichannels with commercial CuO/ZnO/Al₂O₃ catalyst for methanol steam reforming was numerically investigated in this paper. A three-dimensional numerical model was established to study the heat and mass transfer characteristics as well as the chemical reaction rates. The numerical model adopted the triple rate kinetic model of methanol steam reforming which can accurately calculate the consumption and generation of each species in the reactor. The effects of steam to carbon molar ratio, weight hourly space velocity, operating temperature and catalyst layer thickness on the methanol steam reforming performance were evaluated and discussed. The distributions of temperature, velocity, species concentration, and reaction rates in the reactor were obtained and analyzed to explain the mechanisms of different effects. It is suggested that the operating temperature of 548 K, steam to carbon ratio of 1.3, and weight hourly space velocity of 0.67 h⁻¹ are recommended operating conditions for methanol steam reforming by the novel multichannel reactor with catalyst fully packed in the parallel minichannels.     

深海剖面测量系统设计

文章介绍了一种深海剖面测量系统的总体和软硬件设计,并给出了试验数据。该深海剖面测量系统利用浮力调节来控制测量平台升降,升降测量平台搭载CTD传感器、海流计等测量仪器,在升降过程中完成长时间深海环境参数剖面测量,是一种低功耗、高效率的海洋观测系统。     

基于FPGA/DSP的捷联惯导系统设计

介绍了一种基于FPGA/DSP的捷联惯导系统的软硬件设计;详细提供了系统的硬件架构(包括系统框图、基于CPLD的六通道V/F采集电路、DSP芯片自举系统的基本连接框图)、各模块的设计方案和软件流程图,选用了四元素和旋转矢量相结合的方法解算姿态矩阵,并且在计算旋转矢量的同时计算加速度,进一步提高了导航系统的精度;系统导航试验结果表明,该系统精度高,动态特性好,可靠性高。     

Thermal management in PEMFCs: The respective effects of porous media in the gas flow channel

This study aims to evaluate the convective heat transfer enhancement of the proton exchange membrane fuel cells (PEMFC) numerically. As the higher heat transfer surfaces lead to higher heat transfer rates, a flat plate porous layer is utilized in the gas flow channel (GFC). This enhancement in heat transfer stems from the corresponding modification in the temperature and velocity profiles. The influencing parameters on these profiles are the thickness, permeability, and porosity of the GFC porous layer. After performing the simulations, the results indicate that convective heat transfer has a direct relationship with GFC porous layer's thickness and permeability. However, lower values of porosity lead to the higher Nusselt numbers. Previous investigations have also mentioned the positive impact of the microporous layer (MPL) on the water management of these fuel cells. Therefore, six different sizes of MPL and the gas diffusion layer (GDL) are utilized to evaluate their impacts on the thermal management. Results indicate that although these sizes have negligible effects on the heat transfer, Nu increases by enhancing the total size of MPL and GDL. The results also show that thicker MPLs lead to higher heat transfer rates. The evaluation of the friction factor also indicates the adverse effect of the GFC porous layer, although this undesirable effect is negligible. Finally, all the simulated values are utilized to train an artificial neural network (ANN) model with high precision. This ANN model can produce more data for sensitivity analysis and presenting respective 3D diagrams of the influencing parameters on heat transfer.     

小型无人艇自航自控船模试验

设计一套应用于小型无人艇的自控自航船模数据采集与分析系统,此系统以PAC为核心部件,通过开发的基于VB.NET语言的控制程序,可以实现远程遥控操作,并对测量传感器的数据进行同步采集,试验数据可实现在线实时分析处理。应用此系统对某小型无人艇船模进行了快速性试验,并对试验结果进行分析和处理,表明自航自控船模数据采集与分析系统工作可靠,得到的结果准确实用,而且具有良好的发展前景。     

连动式聚能爆破装置的应用探讨

对接触扫雷技术作了简要说明,同时对锚雷的基本结构、水下状态及传统的失效方法进行了扼要地叙述,重点对该型连动式聚能爆破装置的应用方式及各组成部分的功能设计等方面进行了探讨;以期对从事反水雷装备技术研究人员有所借鉴。     

无人水下航行器发展与应用

无人水下航行器作为无人运载平台的一个重要分支,在民用领域和军用领域都发挥着极其重要的作用。首先介绍了几个发达国家UUV的发展现状及其未来发展计划,强调了UUV的应用领域,如海洋探测与开发、水雷对抗、潜艇对抗等等,在此基础上分析了UUV发展必须突破的几项关键技术,如能源问题、自主导航、协同使用等等。     

一种低过载弹身分离技术研究

针对传统干扰弹采用火药进行弹身分离布放时,存在干扰机承受瞬时过载冲击过大的问题,提出了一种通过控制仓段连接强度,利用固体燃气发生器机构缓慢释放高压燃气,降低分离压力峰值的弹身分离方法。实验表明该方法可以有效降低分离过载,减小干扰机承受的过载冲击。     

电磁拔销器在某引信中的应用

某型产品要打击多种状态目标,但可利用于解除保险的环境比较少,为解决这个问题,将电磁拔销器应用在引信中。该引信通过离机环境给电磁拔销器上电后吸附保险销,解除保险。并在隔爆部件运动到位后,给电磁拔销器断电,释放保险销,锁定隔爆件。实验验证了其方案可行。     

水雷引信控制系统的低功耗设计

引入水雷引信控制系统的低功耗设计思想,选用MSP430f1611作为系统的微控制芯片并经过精心的外部电路设计,实现了控制系统低功耗,可靠的运行。试验证明,在有限的电池容量条件下此控制系统能够极大的延长工作时间。