机械式制冷热管对多年冻土的制冷效果研究

多年冻土区路基防护技术是冻土科研人员长期研究的重点。基于多年冻土区现场试验,对研发的新型机械式制冷热管与普通热管的制冷效果进行对比分析。结果表明:(1)机械式制冷热管可以弥补普通热管在暖季不能工作的缺陷,能在暖季和寒季同时带走活动层中的热量,增加冷储量,有效保护多年冻土;(2)分别在寒季和暖季,机械式制冷热管比普通热管的侧壁温度在活动层中低2. 77～0. 39℃、1. 22～0. 13℃,在多年冻土层2. 0～6. 0 m深度范围中低3. 24～0. 52℃、0. 55～0. 12℃,机械式制冷热管年均温度比普通热管年均温度在活动层和多年冻土层中均低0. 74℃;(3)分别在暖季和寒季,机械式制冷热管的积温是普通热管积温的1. 4倍～2. 1倍、1. 4倍～1. 8倍,机械式制冷热管的年积温是普通热管年积温的1. 9倍。研究成果可为新型机械式制冷热管技术在多年冻土热稳定维护中的应用提供理论依据。     

The Trends and Tasks of Modeling and Simulation for Reduction of Heat Treatment Distortion

IntroductionTherearemanyfacorswhichinfluencethedistortonofworkpieceandeveryheattreatInentengineerssWandtrytofindordevelopmodelsandsimulationmethodstoestimateandreducedistortonorwarpage.VariousmodelshavebeenandbeinginvestigatOdtoestimatetheinduenceoffacorsontfansformahonkinetics,hardness,residualstressanddistOrtionarerCPortCdatmanyconferences,.HowevefHEARTS[l]andafewofothermodelshavebeendeveloPedandcontrthutingtounderstandandPredicttheialluenceofrelatngfacors[2-1o].EVenstillmanyhazardous…     

散热器性能评价和标定

评价散热器性能的主要指标是散热器Ｑｎ，和空气阻力△Ｐａ，Ｑｎ数值愈大，散热效果愈好，△Ｐａ则正好相反，分析介绍了风扇功率判别法和风扇特性曲线判别法，首次提出了动压差判别法。通过对以上三种判别方法的对比分析，提出了应建立散热器模拟试验台的建议。     

Assessment of the influence of different cooling system configurations on engine warm-up, emissions and fuel consumption

One of the major goals of engine designers is the reduction of fuel consumption and pollutant emissions while keeping or even improving engine performance. In recent years, different technical issues have been investigated and incorporated into internal combustion engines in order to fulfill these requirements. Most are related to the combustion process since it is responsible for both fuel consumption and pollutant emissions. Additionally, the most critical operating points for an engine are both the starting and the warming up periods (the time the engine takes to reach its nominal temperature, generally between 80°C and 90°C), since at these points fuel consumption and pollutant emissions are larger than at any other points. Thus, reducing the warm-up period can be crucial to fulfill new demands and regulations. This period depends strongly on the engine cooling system and the different strategies used to control and regulate coolant flow and temperature. In the present work, the influences of different engine cooling system configurations on the warm-up period of a Diesel engine are studied. The first part of the work focuses on the modeling of a baseline engine cooling system and the tests performed to adjust and validate the model. Once the model was validated, different modifications of the engine coolant system were simulated. From the modelled results, the most favourable condition was selected in order to check on the test bench the reduction achieved in engine warm-up time and to quantify the benefits obtained in terms of engine fuel consumption and pollutant emissions under the New European Driving Cycle (NEDC). The results show that one of the selected configurations reduced the warm-up period by approximately 159 s when compared with the baseline configuration. As a consequence, important reductions in fuel consumption and pollutant emissions (HC and CO) were obtained. On doctoral leave from Universidad Technológica de Pereira (Colombia)     

用激光多普勒测速仪测量发动机缸头冷却水流场

本文用激光多普勒测速仪测量发动机冷却水的流场,通过计算机绘制了缸头冷却水腔二维流场分布, 为寻求发动机气缸头冷却水合理的流场分布,避免出现流动死区,使发动机在一定的冷却水流量下保证气 缸头良好的冷却提供了基础。     

H55全液压挖掘机高温故障诊断

针对Ｈ５５型挖掘机在高达６０℃左右的环境温度下进行挖炉渣作业时出现的１２０℃的高温故障，对原机型油路系统的设计进行了分析及发热计算，并在此基础上提出了排除油温过高的有效措施。