某欧Ⅳ柴油发动机EGR冷却系统优化设计

本文通过对某欧Ⅳ柴油发动机EGR冷却系统的优化设计,解决了原型机EGR冷却系统设计不合理,使得EGR阀入口废气温度过高导致EGR阀烧蚀失效的问题。同时通过耐久试验验证,确定了流经EGR阀废气温度的合适范围。对EGR冷却系统的设计开发都具有指导意义。     

EGR对增压柴油机排放特性的影响

废气再循环(EGR)是降低柴油机NOx的一条有效技术路径.对于轻型车用增压中冷柴油机,采用从涡轮前取气回流到压气机后的高压EGR系统.应用真空驱动的弹簧膜片式EGR阀,真空度由控制器根据输入的电压信号量决定,从而控制EGR阀的开度.在不同工况下,研究了EGR阀的流通特性,分析了柴油机的HC、CO、NOx排放,烟度和比油耗随EGR率的变化规律.     

增压柴油机EGR阶跃工况瞬态响应特性仿真分析

建立了带EGR回路的增压柴油机瞬态仿真平台并验证了准确性.为了缩短EGR阶跃工况的响应时间,进行了EGR阀开度阶跃时间、开阀特性、目标EGR率等影响因素的不同控制策略的对比.结果表明,缩短EGR阀开度阶跃时间,采用“上抛型”开阀控制策略,可改善EGR流量等参数的瞬态响应特性,但会造成转矩波动增加.为减少转矩波动,提出了...     

电磁驱动式EGR阀原理与试验研究

介绍了一种以电磁驱动作为动力源的新型EGR阀,对该阀的结构形式、工作原理、驱动电路等进行了详细阐述。试验结果表明,该阀在开闭的响应时间、EGR率控制精度等性能方面与真空式EGR阀相比具有较大的优势,完全能适应电控发动机排放满足国III以上对EGR阀性能的要求。     

增压柴油机采用废气再循环的燃烧过程和排放特性研究

对于轻型车用增压中冷柴油机,采用从涡轮前取气回流到压气机后的高压EGR系统.应用真空驱动的弹簧膜片式EGR阀,在不同工况下,研究了EGR阀的流通特性,分析了柴油机的HC、CO、NOx排放、烟度和比油耗随EGR率的变化规律.研究了EGR对柴油机燃烧过程的影响,并对排放变化规律作出解释.     

TRIZ创新方法在EGR阀布置设计中的应用

基于TRIZ创新方法,分析废气再循环(EGR)阀布置中面临的矛盾和问题,并进行概念设计。在EGR布置概念设计完成后,进行概念设计验证,确认EGR阀布置设计的开发结果。     

本田雅阁轿车热车怠速不稳故障的排除

一部本田雅阁轿车在拆装发动机及变速器总成后 ,当装复试车时就出现了冷车怠速一切正常、而热车后怠速不稳的现象。该车发动机采用了EGR系统 ,该系统中EGR阀的真空是由2个相互串联的EGR控制电磁阀和EGR真空控制修正阀共同控制的。从进气歧管上方的真空增压罐来的真空源经过EGR真空控制修正阀 (VCV)压力调整后 ,再由EGR控制电磁阀控制到EGR阀的真空通道 ,最后再作用到EGR阀的真空膜片上 ,达到调节燃烧后的废气进气歧管参加再循环燃烧多少量的目的。首先 ,利用自诊断系统读取发动机故障码 ,发动机电控系统没有故障储存 ,检查各连接…     

一种文丘里EGR方案的废气流量计算方法

针对废气再循环(exhaust gas recirculation,EGR)控制方法瞬时响应性差、跟随性差的问题,提出利用文丘里流量公式计算EGR阀的需求开度,根据经过EGR阀的废气需求流量与实际废气流量的偏差进行闭环修正,得到EGR阀的控制开度。通过MATLAB/Simulink软件平台对EGR控制策略进行离线仿真,将该控制策略集成在发动机控制系统中并在硬件试验台架上进行验证。结果表明,基于废气流量闭环的文丘里EGR方案能够更好地提高空气系统控制准确度及瞬时响应性。     

一种实用节能减排型步进式电机控制EGR阀

针对电子控制式EGR存在结构复杂,能耗高以及可靠性不高等缺点,将步进电机引入对EGR阀的控制中,设计了包括步进式电机、EGR控制阀、各传感器和电子控制器ECU等部件在内的实用节能减排型步进式电机控制EGR阀。结果表明,实用节能减排型步进式电机控制EGR阀不但具有结构简单,能耗小以及可靠性高的特征,而且还能有效地提高燃油的利用率,减少尾气中氮氧化合物的含量。     

某EGR蝶阀的设计与计算

废气再循环(EGR)阀是废气再循环装置中的关键部件,并对其性能和可靠性有很大影响,本文对EGR蝶阀进行了结构设计,利用计算流体动力学(CFD)软件STAR-CCM+,对EGR阀流体腔内的废气进行了模拟分析,并用实验验证了设计的正确性和模拟分析结果的合理性。     

An analysis for solar central receiver systems with terminal concentrators or variable apertures

A central receiver system, having a downlooking cavity and a field of focusing heliostats, is analyzed in the absence and in the presence of a terminal concentrator. Researches compared calculated collector performance to the given characteristics determined by Ref. [2], at a specific site location of Sandia Laboratory, Albuquerque. New Mexico. This study presents a proposal for a central receiver cavity with an irised aperture. Concentration ratios and efficiencies were obtained for comparison with a fixed aperture system. The proposed system demonstrates improved performance. If the advantages of the system over the lifetime of the installation proved to outweigh the disadvantages of the extra cost and complexity, the proposed design would be desirable.     

电厂锅炉油枪节油改造

国电丰城发电有限公司锅炉在安装等离子点灰系统后,锅炉启动方式改变,锅炉燃油系统作用发生变化且油枪出力增大。通过将锅炉燃油系统油枪的雾化由蒸汽改为压缩空气,更改孔径小的油枪喷头,锅炉启动用油大幅度减少,取得良好的经济效益。     

中型太阳能中药饮片干燥装置

研制成一套采光面积为１５８ｍ＾２，太阳能与蒸汽互补，日产１０００ｋｇ中药饮片的太阳能干燥生产装置。采用热性能测试及控温湿干燥方法，进行了干燥装置技术经济性能的实验研究。     

Electricity generation using solar parabolic dish system with thermoelectric generator—An experimental investigation

The present electricity grid installation cost as well as the tariff is quite high in India, particularly remote rural areas, to electrify houses. These problems can be easily solved by installing standalone systems that operate on one of the clean energy sources such as solar energy. An experimental analysis of generating electricity from a thermoelectric generator (TEG) powered by a solar parabolic dish concentrator device with aperture area and focal length of 12.6 m² and 2.42 m, respectively, is presented in this article. A TEG is made up of a thermoelectric module connected to a flat receiver by an absorber layer. The studies were carried out in Indian climatic conditions at the National Institute of Technology, Puducherry. Over a spectrum of beam radiation, the system's maximum energy conversion efficiency, as well as efficient electrical output, are evaluated and presented. The proposed system's average effective electrical efficiency is 0.424%, corresponding to the TEG's average energy conversion efficiency of 2.76%.     

Cost of paraboloidal collectors for solar to thermal electric conversion

Much is underway concerning technical and design aspects of solar collectors and associated costs of point designs. But little has been published on the tradeoffs between alternative designs and large-scale manufacturing possibilities. To fill this gap, close interchange is needed among those versed in technical and systems design, manufacturing and costing. The solar to thermal electric power study funded by the National Science Foundation and carried out by Colorado State University and Westinghouse Electric Corporation has led to the assembly of such a team. This team is obtaining new data on large-scale production of concentrating collectors of widely varying parameters.

Investment and other costs of paraboloidal collectors with various aperture widths, reflectivities, rim angles, and accuracies of contour and tracking are reported herein. In studying alternative design-cost-performance relationships, emphasis is placed on breadth of coverage rather than on detailed accuracy. Alternative aperture widths led to preferences for different production processes that are not particularly sensitive to changes in rim angle or reflectivity. Significant cost relationships in the manufacture, installation and maintenance of collectors were found; other relationships are less certain. Besides the above, study results indicate directions for further study.     

高拱坝蓄水水位对横缝开度的影响研究

研究了蓄水水位对横缝开度的影响．确定坝前允许最高水位以满足灌浆需要是工程上亟待解决的问题。推导了上游水压作用下横缝宽度变化量的计算公式．并采用模拟拱坝浇筑、灌浆和蓄水过程的有限元仿真方法.研究不同蓄水水位对横缝开度的影响。结果表明．当水位达到距灌浆区底部高程以下30～40m时．水压对缝宽的压紧闭合效果开始变得显著。     

在役机车轮箍内径面不良状态浅析

通过对在役机车轮箍内径面各种不良状态的统计分析,揭示出其分布特点,并指出了轮箍内径面加工、检查中应注意的问题。     

串联环翼式桥墩间冲刷防护影响研究

环翼式桥墩纵向串联布置时,为深入研究桥墩局部冲刷防护问题,从减小冲坑大小和近底垂向流速的方向出发,通过制作桥墩模型,设计正交试验,研究单向水流条件下桥墩间距、下游侧桥墩防冲板的安装高程及数量对两个纵向串联桥墩中下游侧桥墩的冲刷深度的影响,并对所测结果进行极差分析和SPSS方差分析。结果表明,下游侧桥墩防冲板安装高程的显著性比两桥墩间中心间距大小和下游侧桥墩防冲板安装数量的显著性要高,且下游侧桥墩防冲板的安装数量对桥墩冲刷的影响最小,影响效果从大到小依次为下游侧桥墩防冲板的安装高程、桥墩间距、下游侧桥墩防冲板的安装数量。     

支吊架零部件重量及吊零方式对弹簧选型和管道应力分析的影响

本文通过大量的计算,分析了支吊架零部件重量及吊零方式对管道位移、载荷、应力、模态频率和弹簧型号的影响。结果表明,冷态吊零比热态吊零具有更小的OPE运行应力和SUS持续应力;一次应力计算获得的弹簧载荷整定值约比准确值低6％;使用两次应力计算可获得精确的弹簧整定值;一次计算加上支吊架零部件重量再重新计算弹簧也能获得比较准确的整定值。     

Solar thermal electric power systems: Comparison of line-focus collectors

Three types of line-focusing collectors: parabolic though, fixed slats with movable absorber and movable slats with fixed absorber, are evaluated to find those systems that are capable of producing the lowest costs of electrical energy. Minimum costs per kW-hr are found using sequential optimization techniques that consider variations in rim angle, reflectance, aperture width, length, orientation, tracking, contour error, slat width, slat curvature, tangent slat angle, slope, installation methods, materials, fabrication methods, absorptance, emittance, cover transmittance, field shape, layout, pipe sizes, insulation thicknesses and turbine-generator-cooling lower efficiencies and designs. This approach provides a uniform treatment of both cost and performance for a solar thermal electric power system. This uniform treatment of solar thermal electric power systems for all collector types insures that valid comparisons are made.