Capillary force of a novel skew-grooved wick structure for micro heat pipes

In order to improve the capillary force of grooved wick, a novel skew-grooved wick structure was proposed for micro heat pipes. Risen meniscus experiments were carried out to research the capillary force of the skew-grooved and rectangle-grooved wick and a comparison of capillarity between the two wick structures was explored. A theoretical capillary force model of skew-grooved wick structure was also developed to calculate its effective capillary radius by comparing with the rectangle-grooved wick. From the experimental results, the maximum capillary force of the skewed-grooved wick is 8.62% larger than that of the rectangle-grooved wick. From the theoretical analysis, because the skewed-grooved wick has a smaller effective capillary radius, its maximum capillary force is 8.64% larger than that of the rectangle-grooved wick. The results indicate that the skew-grooved wick provides larger capillary force than the rectangle-grooved wick.     

Fabrication and thermal performance of grooved-sintered wick heat pipe简

Some novel grooved-sintered composite wick heat pipes（GSHP） were developed for the electronic device cooling.The grooved-sintered wicks of GSHP were fabricated by the processes of oil-filled high-speed spin forming and solid state sintering.The wick could be divided into two parts for liquid capillary pumping flow：groove sintered zone and uniform sintered zone.Both of the thermal resistance network model and the maximum heat transfer capability model of GSHP were built.Compared with the theoretical values,the heat transfer limit and thermal resistance of GSHP were measured from three aspects：copper powder size,wick thickness and number of micro grooves.The results show that the wick thickness has the greatest effect on the thermal resistance of GSHP while the copper powder size has the most important influence on the heat transfer limit.Given certain copper powder size and wick thickness,the thermal resistance of GSHP can be the lowest when micro-groove number is about 55.     

Development of sintered Ni-Cu wicks for loop heat pipes

The present study fabricated a series of capillary wicks for loop heat pipes (LHPs), using two different methods, the cold-pressing sintering and direct loose sintering, and experimentally investigated the effect of different methods, compositions and sintering parameters on their properties in terms of porosity, permeability and pore radius. Porosity and pore radius were measured by the Archimedes method and Scanning Electron Microscope (SEM), respectively. Permeability of the wicks was compared by calculation using empirical equation. Results show that capillary wicks were successfully fabricated by using two different methods; the optimal capillary wick was found to be sintered at 650°C for 30 min, using direct loose sintering technique, with 90% nickel and 10% copper. The wicks could reach the porosity of 70.07% and the permeability of 10⁻¹³ m² order, with mean pore radius of 0.54 μm. Supported by Shandong Provincial Program of Science and Technology Development (Grant No. 2007GG1HZ06004)     

Thermal performance of heat pipe with different micro-groove structures

Four kinds of micro heat pipe of trapezoidal groove wick structure with different numbers of grooves or aspect ratios were studied and compared about thermal transfer performances in order to optimize the manufacture of micro heat pipe with groove wick structure. The results show that these micro heat pipes have excellent performance in heat transfer; the equivalent thermal conductivity coefficient is two orders of magnitude compared with that of copper; the number and aspect ratio of grooves have a prominent effect on the performance of such thermal transfer. The optimum number of grooves is lower than 60 and the best aspect ratio is near to 1.5. The temperature and thermal transport rate are almost directly proportional relationship, but this relationship will be broken up suddenly when the critical heat flux is reached.     

热管余热锅炉在回收工业余热中的优势探讨

介绍了热管及热管余热锅炉的原理及特性,并针对一些重要参数进行了烟气焓值和热平衡 问题分析计算,热管余热锅炉比普通余热锅炉提高效率５０％。压降减小５０％,在实现同样热能效果 的前题下,前者的重量和占地空间均为后者的一半．     

热管用于半导体致冷器的实验研究

本文作者为半导休致冷器设计了一种低温铝氨热管，并对其处于自然对流和强迫顺掠散热工况下的传热特性作了研究。半导体致冷器利用热管散热具有无可比拟的优点，目前的半导体致冷器的制造工艺条件，为其广泛应用带来光明的前景；本文指出：热管用于半导体致冷器的关键在于热管同电堆的耦合关系和结构设计。     

热管中冷器的传热与阻力特性

为了研究重力热管在车辆中冷器上的应用可行性,设计用于冷却高温增压空气的热管中冷器.选用水作为工作介质,在风洞实验台架上进行热管中冷器的传热和阻力性能实验.测试热管中冷器在不同冷侧空气流速、冷﹑热侧空气进口温差、热侧空气流量下的散热量和压力降,比较并分析测试结果.结果表明,热管中冷器具有良好的散热性能,在一定范围内可以满足高增压内燃机的散热要求.将实验结果与理论模型计算值进行比较,结果表明,实验值与理论计算值变化趋势吻合较好．     

循环冷却水系统中铜管换热设备腐蚀的防止

提出了几种循环冷却水系统中铜管换热设备腐蚀的防止方法 ,并通过实际综合应用 ,取得较为理想的防腐效果 ,腐蚀率为 0 .0 0 2 8mm/a ,远低于控制标准 0 .0 0 5mm/     

预制保温管敷设应用分析与计算

通过理论计算和实际探索开发出一种符合实际需要的供热直埋管道设计技术 并在实际设计中进行了使用 ,取得了良好的使用效果 该技术在城市供热系统中有广泛的推广价值     

保温热力管有限元热固耦合分析

节能是保温热力管道设计的主要任务之一。利用ANSYS有限元软件进行热力管道和保温层的热-固耦合分析。通过建立模型,确定条件和参数,先后进行热分析和结构分析,得到热力管道和保温层沿定义路径各处的温度场和应力场。分析结果不仅为热力管的保温设计提供参考数据,还为热力管道的节能设计提供帮助。     

热管换热器在化肥工业领域中的应用探索

介绍了热管换热器结构的本质特性 ,并列举化肥工业领域中的几项应用实例 ,同时对热管换热器的设计原则及其在化肥工业领域的研究和开发应用前景提出了建议     

聚光光伏高能流密度不均匀传热的热管散热器设计与计算

考虑到聚光电池表面的高辐射能流密度,相应的热沉温度分布的不均匀性,以及传统热管散热的局限性,设计了一种特殊结构形式的热管组以用于聚光电池散热。通过对其进行数值计算,比较了在不同倾角下热管组的压力场、速度场、温度场、以及相体积分数的分布情况,并将该型热管与普通热管的计算结果相比较,发现该型热管在预防携带极限和干涸极限的发生方面确实要优于普通热管。设计的热管组在高辐射能流密度的条件,消融温度的不均匀性将会起到很好的效果。     

热管式换热器的热力学分析

目前对热管式换热器的研究大都是基于能量守恒定律,从传热学角度研究其传热性能,从热力学能量利用角度进行的研究相当少。本文以热力学第二定律为基础,用(火用)参数对气—气、气—水组合型热管式换热器进行了(火用)优化分析。提出了冷、热流体参数的优化选择方案,并且从热力学观点研究了这种类型换热器的工作效率。此外,本文也为换热器的(火用)分析提供了一个可行的研究方法。     

X射线管热管的研制与工作特性

X射线管的散热问题一直是制约X射线探伤机连续工作时间的一个重要因素。将热管技术应用于X射线管阳极的散热之中是制作X射线管的一次技术更新与大胆尝试，同时热管在X射线管中的成功应用，必将引发X射线技术在探伤技术上的革新。     

热管换热器用于木纤维干燥余热回收的可行性分析

采用热管换热器回收木纤维干燥排气余热为实例,分析计算了回收纤维干燥排废气余热的经济效益。当排气温度为90℃,相对湿度为50%,流量为20 000 m3/h的废气流过热管换热器后,它可使纤维干燥的排气热损失每h减少541.53 kW,实际节能率10.32%。排气余热回收设备总投资预计约204万元,每年可节省标准煤1 152 t,减少煤耗费约92万元,扣除设备折旧费,维修费及运行费用等,投资回收期约3年,从而在理论上论证了采用此节能方案的可行性。     

Effects of bending on heat transfer performance of axial micro-grooved heat pipe

Heat pipe is always bent in the typical application of electronic heat dissipation at high heat flux, which greatly affects its heat transfer performance. The capillary limit of heat transport in the bent micro-grooved heat pipes was analyzed in the vapor pressure drop, the liquid pressure drop and the interaction of the vapor with wick fluid. The bent heat pipes were fabricated and tested from the bending angle, the bending position and the bending radius. The results show that temperature difference and thermal resistance increase while the heat transfer capacity of the heat pipe decreases, with the increase of the bending angles and the bending position closer to the vapor section. However, the effects of bending radius can be ignored. The result agrees well with the predicted equations.     

碳纳米流体特性及其在重力热管内的传热

采用阿拉伯胶辅助分散法制备了一种新型的纳米流体--碳纳米管 水纳米流体,并以其为工质在以铜为管壳的一种新型重力热管内进行了传热实验研究.制备和实验结果表明,碳纳米管 水纳米流体的导热系数比基液水约增加了30％～50％,导热能力明显增强;这种纳米流体黏度低,流动性好,制备过程简单,可用于大规模生产;纳米流体重力热管加热段沸腾换热弱化了纳米流体的稳定性对热管传热性能的影响,实现了纳米流体与重力热管的优势互补;以该纳米流体为工质的重力热管的内热阻比水小,并且随着传输功率的提高,热管总热阻逐渐减小,传热性能逐渐提高.     

气-气热管换热器在电站余热回收中的应用

分析了气-气热管换热器的技术经济性能,并对气-气热管换热器在电站余热回收应用方面的优点及注意事项进行了探讨。