复合蒸汽通道柔性均热板设计及其传热性能研究

近年来,随着科技的发展与进步,各种柔性电子设备得到普及。成倍增长的功耗导致电子芯片在狭小空间内产生过高的热流密度和工作温度,引发了严重的散热问题。然而,传统的均热板因较大的刚性不适用于柔性电子设备。为解决上述问题,文中基于铝塑膜壳体制造了一种具有复合蒸汽通道结构的厚2.2 mm的柔性均热板,并对其在不同灌液量、不同重力方向、不同弯折角度和弯折次数的稳态传热性能进行了测试。结果表明:该柔性均热板的最佳灌液量为700μL;在7 W的加热功率下,其热导率最高可达1264.9 W/(m·℃),为壳体材料(铝塑膜)本身热导率的4517.6倍,其传热性能良好。

蒸汽通道宽度对凝汽器优化布管的影响

以某凝汽器为研究对象,数值模拟其壳侧蒸汽的流动情况,研究了凝汽器留有的蒸汽通道宽度对凝汽器壳侧蒸汽流动以及凝汽器压力的影响.凝汽器蒸汽通道宽度的设置应以使得其内的蒸汽流速适中为宜,流速过大会导致蒸汽流动的不均匀性,增大汽阻;过小会使得蒸汽在管束区内的流动偏低,降低换热效果.

超薄柔性热管蒸汽通道微压印成形及传热性能研究

介绍PMMA壳体超薄柔性热管的制造设备与加工过程。分别采用分离式微压印模具加工的微柱子阵列和高温烧结多层铜丝网作为蒸汽通道和吸液芯,制造厚度0.67mm的超薄柔性热管。研究微压印温度、压力和压印时间对微柱子成形的影响。介绍超薄柔性热管传热性能试验台设计与试验方法,试验结果表明最佳充液量为350~400μL,最高热导率达到924.1 W/(m·K);当超薄柔性热管弯曲90°时,其热导率仍为铜热导率的1.16倍。综上所述,利用微压印成形制作的PMMA壳体超薄柔性热管具有结构灵活、成本低廉以及低蒸汽阻力的优点,是解决柔性可穿戴式电子设备散热难题的理想方案。

HTR蒸汽发生器环形通道内单液滴蒸发行为研究

高温气冷堆进水事故的机理研究对该反应堆安全具有重要意义。本文对液滴在蒸汽发生器环形通道内的流动和传热进行数值模拟研究,采用单液滴模型,利用龙格库塔方法进行求解。结果表明,初始直径小于420μm的液滴将无法运动到环形通道顶部。氦气压力的改变对于液滴完全蒸发需要的时间和液滴最大运动距离影响很小。

高反射低碳排放屋面防水系统在高湿度环境下的应用

某酿酒车间屋面防水项目采用3 mm厚SOPREMA COLVENT FLAM 180 TG蒸汽通道型SBS改性沥青防水卷材+4 mm厚SOPRASTAR FLAM HD GR白色高反射颗粒覆面SBS改性沥青防水卷材组合成的高反射低碳排放屋面防水系统,解决了高湿度环境下暴露式屋面防水层起鼓的问题。本文介绍了上述两款新材料的结构组成与性能特点以及在屋面项目上的施工应用要点。

Multi-walled carbon nanotubes as novel promoter of catalysts for certain hydrogenation and dehydrogenation reactions

From the chemical catalysis viewpoint,the excellent performance of CNTs in adsorption-activation of H2 and in promoting spillover of adsorbed H-species is very attractive,in addition to their nanosize channels,sp2-C constructed surfaces,and high thermal/electrical conductivity.This review examines some recent progresses of CNTs as a novel support or promoter of catalysts for certain hydrogenation or dehydrogenation reactions,e.g.,hydrogenation-conversion of syngas to yield alcohols and decomposition or steam-reforming of methanol to generate H2,mainly based on recent work carried out in our laboratory.

Quantitative description of steam channels after steam flooding

Steam channeling is one of the main barriers for EOR after steam flooding.In order to enhance the oil recovery in steam flooded reservoirs,steam channel volumes should be precisely known.In this paper,a set of methods has been established in order to study steam channeling quantitatively by using dynamic data.Firstly,steam channeling wells are identified through curves of watercut and temperature.Then,considering the hysteresis phenomenon,channeling relations are identified with the correlation coefficients between injection wells and production wells under different conditions.Lastly,an analytic model,in which steam condensation,pressure and temperature are considered,is established to calculate the steam channel volumes.A production well named L31615 in some block in Henan Oilfield in China is systematically analyzed by using the method established.The whole block is further analyzed,and the distribution map of steam channels and the steam channel volumes are obtained.The results show that steam channeling does not only occur inside a well group,but also sometimes occurs between wells in different well groups.The calculation of the steam channel volumes provides a theoretical basis for bringing a remedial action like plugging into operation.

An Experimental Investigation of Heat Transfer Characteristics for Steam Cooling in a Rectangular Channel with Parallel Ribs

An experimental study of heat transfer characteristics in superheated steam cooled rectangular channels with parallel ribs was conducted.The distribution of the heat transfer coefficient on the rib-roughed channel was measured by IR camera.The blockage ratio(e/Dh) of the tested channel is 0.078 and the aspect ratio(W/H) is fixed at3.0.Influences of the rib pitch-to-height ratio(P/e) and the rib angle on heat transfer for steam cooling were investigated.In this paper,the Reynolds number(Re) for steam ranges from 3070 to 14800,the rib pitch-to-height ratios were 8,10 and 12,and rib angles were 90°,75°,60°,and 45°.Based on results above,we have concluded that:In case of channels with 90° tranverse ribs,for larger rib pitch models(the rib pitch-to-height ratio=10 and12),areas with low heat transfer coefficient in front of rib is larger and its minimum is lower,while the position of the region with high heat transfer coefficient nearly remains the same,but its maximun of heat transfer coefficient becomes higher.In case of channels with inclined ribs,heat transfer coefficients on the surface decrease along the direction of each rib and show an apparent nonuniformity,consequently the regions with low Nusselt number values closely following each rib expand along the aforementioned direction and that of relative high Nusselt number values vary inversely.For a square channel with 90° ribs at Re= 14800,wider spacing rib configurations(the rib pitch-to-height ratio=10 and 12) give an area-averaged heat transfer on the rib-roughened surface about8.4%and 11.4%more than P/e=8 model,respectively;for inclined parallel ribs with different rib angles at Re=14800,the area-averaged heat transfer coefficients of 75°,60° and 45° ribbed surfaces increase by 20.1%,42.0%and 44.4%in comparison with 90° rib angle model.45° angle rib-roughened channel leads to a maximal augmentation of the area-averaged heat transfer coefficient in all research objects in this paper.