场协同原理在强化换热器传热中的应用与分析

以提高翅片管式换热器的换热性能为研究对象,根据场协同原理（在相同的速度和温度边界条件下,对流换热的性能取决于流体速度场与热流场协同的程度）,将换热器的基管由圆管改为椭圆管来提高换热器的换热性能。计算结果表明,其换热系数提高15％,阻力系数降低18％,对强化换热器的热力性能有一定的参考价值。     

A New Phenomenon Observed in Determining the Wear-Corrosion Synergy During a Corrosive Sliding Wear Test

Corrosive wear of materials is a complex surface failure process, which involves both the wear-accelerated corrosion and the corrosion-accelerated wear. Separating contributions of these two processes to the total material loss is of significance for gaining better understanding of the wear-corrosion synergy. Previous studies have generated an electrochemical scratch technique for measuring the wear-accelerated corrosion, based on which other components involved in the wear-corrosion synergy can be determined. In this article, a new phenomenon in measuring the wear-accelerated corrosion is reported. It was observed that for non-passivation materials there existed a stirring effect (by pin), which significantly affected the measurement. The resultant mistake was serious. The previous technique was modified accordingly and applied to determine the corrosion-wear synergy of AISI 1045 steel in comparison with that of AISI 304 stainless steel.     

智能化军事物流多维协同研究

目的 从理论、技术与实践融合的视角研究智能化军事物流多维协同问题.方法 通过探讨智能化军事物流的概念,分析智能化军事物流多维协同涉及的基础理论和关键技术,在此基础上提出智能化军事物流多维协同的功能要素,并探索设计多维协同框架模型.结果 结合智能化军事物流面临的理论滞后、标准薄弱、安全重视不够等现实挑战,给出了5个方面的对策建议.结论 智能化军事物流多维协同面临众多挑战,在任务不同的军事物流活动中,需要针对具体场景采用不同的策略.     

结构参数对布置窄缝和挡板的微混合器内流体流动和混合的影响

基于混沌对流原理设计了一种布置窄缝和挡板结构的被动式微混合器,并采用三维数值模拟和可视化实验对该微混合器内流体流动与混合特性进行了研究。窄缝和挡板的共同作用使微混合器水平面内形成了扩展涡和分离涡,垂直流动方向的截面内形成了对称的反向旋涡,多维度涡系显著提高了混合效率。窄缝和挡板的结构尺寸对流体流动和混合有重要影响。综合考虑混合强度和压降,利用场协同原理分析窄缝宽度、窄缝长度、挡板高度对微混合器综合性能的影响并得到了不同Reynolds数条件下的最优结构参数。     

双波纹板束逆流传热与流动的数值模拟和实验研究

利用Fluent软件对一种全焊式双波纹板式换热器的板束传热与流动性能进行数值模拟,运用场协同原理进行强化传热机理分析的同时对双波纹板式换热器进行传热实验,验证数值模拟和理论分析的合理性。结果表明：双波纹结构使得流体在流道形成湍流,减薄板片的层流边界层并且改善了主流区域的速度与温度梯度的协同程度,强化传热。双波纹板束本身的传热系数受到板束热侧入口尺寸的影响,并且在固定尺寸上达到峰值,增大冷热流体入口速度可以提升板束的传热能力,同时也受到压降增大的影响。     

滋味物质间相互作用的研究进展

人类的味觉提供了有关食品质量及其组成的必要信息。人类可鉴别出食物的5 种基本味觉,即甜、咸、酸、苦和鲜味,但食物是多种滋味化合物组成的混合体系,因此滋味物质间相互作用是不可避免的。滋味物质间的相互作用发生在3 个层面,即化合物混合时的化学反应、一种物质对另一种物质滋味受体的影响、混合物质在大脑中的综合感知。其中研究较多的是滋味物质在第二层面上的相互作用。二元、三元及多元滋味物质之间的关系是复杂的：当滋味化合物低强度/浓度混合时呈现增强效应;中等强度/浓度往往呈现加和作用;高强度/浓度混合时常呈现抑制作用。另外,滋味感知受很多因素的影响,如温度、pH值、黏度、硬度、受试者生理状况等。滋味物质间相互作用的研究主要聚焦在饮料滋味改良、药品苦味掩盖和口腔护理产品开发等具有广阔研究前景。     

新型低烟无卤阻燃电缆料的研究

采用改性纳米氢氧化镁Mg（OH）2、微胶囊化红磷（MRP）和热塑性酚醛树脂（PF—T）与低密度聚乙烯（LDPE）复配成低烟无卤阻燃电缆料。通过反复试验得出基料LDPE为100份（质量份）,（PF—T）、MRP和纳米Mg（OH）,的份数比为25：8：40时协同效果最佳,其氧指数达到36,水平燃烧通过FH-1,拉仲强度达13MPa,断裂伸长率为370％。热失重结果表明,协效阻燃体系提高了该复合材料的质量保持率,失重速率明显降低;流变试验表明,添加了PF—T后复合材料的平衡扭矩明显降低;用电子扫描显微镜对复合材料的微观结构分析发现,PF—T和LDPE相容性很好,没有界面产生,无机材料在基料中有很好的分散性。     

蜂窝板换热器内部流动传热特性研究

建立了蜂窝板换热器湍流流动的物理数学模型,并应用数值分析方法模拟了蜂窝板换热器的三维流动传热过程;分析了不同雷诺数下通道内流动阻力和换热性能及其随雷诺数的变化规律,并与相同当量直径的平行平板通道的流动换热性能进行了对比。结果表明,蜂窝板换热器在换热系数提高的同时流动阻力也增大了,在雷诺数Re=3000~15000的范围内,其传热努塞尔数比平行平板增大了0.93~2.12倍,阻力系数增大了2.24~2.35倍。最后从场协同理论的角度分析了蜂窝板强化传热的机理。     

复合翅片传热与流动特性的数值模拟

结合纵向涡发生器和开缝的优点,提出一种复合强化传热翅片,并对该种翅片的传热与流动特性进行数值计算.由于翅片结构比较复杂,在三角形小翼及X形开缝区域应用阶梯逼近进行网格划分.复合翅片的强化作用在于两方面:一是在三角形小翼和X形开缝后的流场均产生了纵向涡,对流体产生较强的扰动;二是带状开缝的间断表面抑制了边界层的增长,平均...     

Two energy conservation principles in convective heat transfer optimization

Improving heat transfer performance is very beneficial to energy conservation because heat transfer processes widely existed in energy utilization systems. In this contribution, in order to effectively optimize convective heat transfer, such two principles as the field synergy principle and the entransy dissipation extremum principle are investigated to reveal the physical nature of the entransy dissipation and its intrinsic relationship with the field synergy degree. We first established the variational relations of the entransy dissipation and the field synergy degree with the heat transfer performance, and then derived the optimization equation of the field synergy principle and made comparison with that of the entransy dissipation extremum principle. Finally the theoretical analysis is then validated by the optimization results in both a fin-and-flat tube heat exchanger and a foursquare cavity. The results show that, for prescribed temperature boundary conditions, the above two optimization principles both aim at maximizing the total heat flow rate and their optimization equations can effectively obtain the best flow pattern. However, for given heat flux boundary conditions, only the optimization equation based on the entransy dissipation extremum principle intends to minimize the heat transfer temperature difference and could get the optimal velocity and temperature fields.