Development of a critical heat flux mapping method for fin-structured surfaces

In this study, we performed critical heat flux (CHF) experiments using structured surfaces to validate the parameter effects and understand their physical meanings. Experimental results showed that the CHF has a peak value as the fin geometry changes. Fins with height of 0.5 mm produced the largest CHF, 1.7 MW/m², and fins longer than 2 mm reduced the CHF values. To explain the results, a CHF mapping method was developed describing the liquid supply-side and demand-side limits. The liquid demand-side limit is governed by the heat removal capability, mainly the nucleate boiling, calculated using the hot spot model. We consider three liquid supply-side limits restricting the liquid supply to the heating surface: capillary limit and counter-current flow limitations (CCFLs). The capillary limit is determined by balancing the capillary pressure and viscous dissipation in the liquid film on the fin side. The CCFL in the structure is calculated using the Wallis correlation and the CCFL in the free volume limits the liquid downward flow by the vapor jetting from the heating surface. The CHF map for our experimental results successfully describes the CHF trend of the structured surfaces. As a result, we concluded that CHF mapping method is an effective means of explaining CHF in pool boiling.     

超薄型双波浪带管带式水散热器技术的应用研究

对超薄型双波浪带管带式水散热器技术在履带式车辆中的应用进行了分析研究,通过部件的台架对比试验、车辆的环境适应性跑车试验以及对部件的体积、质量分析表明,超薄型双波浪带管带式水散热器技术在履带式车辆的应用得到了在系统散热能力提高、水散热器部件散热能力不降低的前提下减轻散热器组件质量的效果．     

钢质T形翅片管的池沸腾传热研究

<正>1 引言 随着对传热过程这一客观规律认识的深化以及加工制造技术的进步,人们已能研制开发出各式各样的强化换热元件,并在工程实践中取代传统的光滑管从而取得省材节能的双重效果。T.C.Canavos曾预言:到目前为止,强化换热元件的工作还仅仅是个开始,但是它的好处是那样地明显,以至于普通光滑管之被淘汰只不过是一个时间的问题了。多年来的实践证明这种预言是正确的,在强化换热元件中,强化液体泡核沸腾的元件的研究进展尤为突出,自60年代末期以后,先后有4种管型实现商品化,其中一种就是T形翅片管（Gewa-T）。T形翅片管自1978年问世于原联邦德国的Wieland Worke公司以后,国内外已有多项研     

花瓣状翅片管套管间润滑油强化传热性能

<正> 1 引言 润滑油在管外环隙间轴向流动时,由于流体粘度大,雷诺数小,一般为层流,光滑管的传热膜系数很低,在本实验范围,Re=300～1000,Pr≈200,油冷却时传热膜系数仅为240～360W/(m~2·℃)。本研究采用花瓣状翅片管强化环隙间润滑油的冷却传热,可有效地扩大传热表面积,并使高粘流体在翅片管三角齿形翅片间轴向绕流到达翅根部,翅间流动死角较小,在本实验范围内,以光坯管面积计的传热膜系数在较好的管参数时可达800～3500W/(m~2·℃)。花瓣状翅片管是对高粘流体较好的一种传热管型。     

混合制冷工质在管束外的冷凝传热强化研究

研究了非共沸混合制冷工质Ｒ１４２ｂ／Ｒ１３４ａ和Ｒ２２／Ｒ１５２ａ／Ｒ１２４在花瓣形翅片管管束外冷凝传热性能,实验结果表明花瓣形翅片管能显著地强化非共沸混合制冷工质的冷凝传热。     

主鳍/襟翼鳍船舶减摇联合控制系统的研究

提出了主鳍／补救翼鳍船舶减摇联合控制系统,并对其进行了控制方案的研究,首先对系统进行了建模,根据水动力数据。采用加权最小二乘对扶正力矩进行线拟合。考虑到随机测量误差和测量的工程可实现性,采用卡尔曼滤波器构成系统的状态估计器,并在此基础上,采用ＬＱＧ控制理论,对系统进行了控制规律的设计。     

空气在不同管束的螺旋隔板换热器壳侧传热与流阻性能实验研究

以现场的压缩空气为工质,分别对花瓣状翅片管（ＰＦ管）与低肋管在螺旋隔板的支承下的传热与流阻性能进行了实验研究,研究结果表明花瓣状翅片管比低肋管具有更优越的传热性能,在同等的传热量下,ＰＦ管螺旋隔板换热器的气侧传热系数比低胁管螺旋隔板换热器高出２０％￣５０％,其压力损失比低肋管低３０％￣４０％。     

建筑幕墙玻璃肋板节点设计探讨

对导致玻璃肋支撑体系的点支式幕墙、全玻幕墙承载能力出现非预期降低的影响因素进行分析,并在行业中首先提出了避免出现该类隐患的设计计算公式和构造设计方法。     

使用R407C冷媒的翅片管冷凝器的计算机模拟

本文针对R22的替代工质R407C,采用稳态分布参数法,对翅片管冷凝器进行了计算机模拟：对制冷剂整个流动方向的温度、饱和温度、干度、换热量、压力、管内换热系数进行了模拟计算并加以分析,并以回路为基本单位,比较了回路之间换热情况的差别,为系统的仿真以及使用R407C的翅片管冷凝器的设计打下基础。     

Effects of particle fouling and magnetic field on porous fin for improved cooling of consumer electronics

The combined effect of particulate fouling and magnetic field on the efficiency of a convective–radiative porous fin heatsink with temperature‐dependent thermal conductivity is presented. The developed thermal models are solved using differential transformation method. The effects of thermal conductivity, porosity, convection, radiation parameter, and thermal fouling number on the fin thermal efficiency are investigated. The presence of thermal fouling on the surface of the fin is shown to increase the temperature distribution. The presence of particle deposition on the fin surface significantly decreases the rate of heat transfer as additional thermal resistance of the fouling layer decreases the thermal performance of porous fin heatsink. Moreover, the fin efficiency decreases as the value of fouled Biot, Darcy, radiation number, and thermogeometric parameter increases. It is established that M_f < M_c, which indicates that the efficiency of the fouled fin is greater than the efficiency of the clean fin. Furthermore, the result of the present study is validated with the established results of Chebyshev spectral collocation method and fourth‐order Runge–Kutta with shooting method and an error margin of 0.000000023 is established.