Performances of electrically heated microgroove vaporizers

An electrically heated microgroove vaporizer was proposed. The vaporizer mainly comprised an outer tube, an inner tube and an electrical heater cartridge. Microgrooves were fabricated on the external surface of the inner tube by micro-cutting method, which formed the flow passage for fluid between the external surface of the inner tube and the internal surface of the outer tube. Experiments related to the temperature rise response of water and the thermal conversion efficiency of vaporizer were done to estimate the influences of microgroove＇s direction, feed flow rate and input voltage on the performances of the vaporizer. The results indicate that the microgroove＇s direction dominates the vaporizer performance at a lower input voltage. The longitudinal microgroove vaporizer exhibits the best performances for the temperature rise response of water and thermal conversion efficiency of vaporizer. For a moderate input voltage, the microgroove＇s direction and the feed flow rate of water together govern the vaporizer performances. The input voltage becomes the key influencing factor when the vaporizer works at a high input voltage, resulting in the similar performances of longitudinal, oblique and latitudinal microgroove vaporizers.     

Preparation of oriented linear copper fiber sintered felt and its performance

Long metal fibers were manufactured in horizontal lathe with a multi-tooth tool. Based on the coarse antler surface structure of copper fibers, a new sintering technology was put forward to manufacture a kind of oriented linear copper fiber sintered felt. The sintering mechanism of oriented linear copper fiber sintered felt was studied. Compared with sintered copper-wire felt, the characteristics of sintered copper-fiber felts were analyzed in details. Owing to the coarse antler surface structure of copper fibers, oriented linear copper-fiber felt was sintered under the condition ofmicro/nano scale range, and copper fibers easily bonded together in the sintering process. Microchannels with micro-scale coarse antler surface structure were constructed. These characters give oriented linear copper fiber felt some new merits： high filtration accuracy, high flow capability, low resistance loss, good capability to resistance pressure, stable and uniform pore, high specific surface area. The properties of oriented linear copper fiber sintered felt were analyzed.     

基于复合正交试验的犁削—挤压参数优化设计

基于复合正交试验方法,研究了单齿犁削—挤压过程的参数优化,为热管内表面吸热芯多齿犁削—挤压过程的优化设计提供了参考依据。对单齿犁削—挤压过程中影响翅形貌的多种因素及水平值进行分组,对两组因素的主次关系和优水平进行了试验研究。试验结果表明,得到的刀具参数优化值为β=30°,α=-8°,h=0·6mm,H=4mm,θ=45°,η=35°;工艺参数优化值为αp=0·24mm,V=113mm/s。     

微沟槽热管拉削成形工艺及其传热性能研究

提出一种热管内表面微沟槽拉削成形方法,利用多齿拉刀在铜管内表面的挤压作用加工出具有连续翅结构的微沟槽,并通过实验研究了微沟槽热管的启动性能、等温性能以及不同倾角下传热功率.结果表明:拉削成形微沟槽热管在约(15～20)s内实现启动,具有快速热响应能力;热管还具有良好的等温性能,蒸发段和冷凝段的温差较小;热管内真空度对热管传热性能有很大的影响;热管在重力辅助条件下传热功率最大,水平放置时次之,反重力状态下传热功率最差.     

Development of high-aspect-ratio microchannel heat exchanger based on multi-tool milling process

A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels with manifold structures. On the basis of multi-tool milling process, the structural design of the manifold side height, microchannel length, width, number, and interval were analyzed. The heat transfer performances of high-aspect-ratio microchannel heat exchangers with two different manifolds were investigated by experiments, and the influencing factors were analyzed. The results indicate that the magnitude of heat transfer area per unit volume dominates the heat transfer performances of plate-type micro heat exchanger, while the velocity distribution between microchannels has little effects on the heat transfer performances.     

基于切削铜纤维烧结的大功率LED微型换热器性能研究

针对大功率LED热流密度高的问题,提出一 种基于切削铜(Cu)纤维烧结的微型换热器水冷散热系 统。实验研究了烧结切削Cu纤维的孔隙率以及复合形式对LED芯片表面温度和换热器进 出口压降的 影响规律。实验结果表明,对于单一型烧结纤维微型换热器,在入口流量相同的情况下,孔 隙率为80%的 烧结纤维微型换热器对芯片表面的散热性能最优,而孔隙率为75%的 烧结纤维微型换热器压力损失最大; 对于复合型烧结纤维微型换热器,在入口流量相同的情况下,复合Ⅲ型(80~85%)烧结纤维微型换热器的 散热性能最好,而复合Ⅰ型(75~80%)烧结纤维微型换热器的进出口压 降最大。     

定向切削铜纤维烧结成形（英文）

分析定向切削铜纤维烧结载体的成形机理,研究烧结温度、烧结氛围和烧结时间对烧结成形的影响,并且分析不同烧结条件下烧结纤维的拉伸力学性能。结果表明,烧结温度和烧结氛围对烧结成形具有重要影响,而烧结时间的影响不是特别显著。在低温还原氛围和800°C下烧结60 min,可以形成烧结颈使得纤维之间紧紧连结在一起,并且在纤维表面形成粗糙的微结构,同时可以获得最佳的拉伸力学性能。     

绿色制造工艺技术在机械工业中的应用研究

对绿色制造工艺技术的概念及其具体内容进行了介绍,并基于绿色制造工艺技术的内涵来着重讨论绿色制造工艺技术在机械工业中的应用.     

微小型薄壁内沟槽铜管旋压缩径数值模拟

文章以有限元分析软件MSC.Marc为平台,建立了微小型薄壁内沟槽铜管钢球高速旋压缩径成形的三维弹塑性有限元模型,对缩径过程的变形机理、应力应变分布和受载情况进行了分析;同时,进行了成形过程实验研究。模拟与实验结果表明,沟槽底部的等效应力应变远大于齿形和沟槽管外表面,钢球与沟槽管接触区受三向压应力作用;等效应变沿轴向呈分层分布,沿周向呈间隔分布;轴向进给速度过大,沟槽管容易出现扭曲变形,轴向拉拔力和钢球承受载荷也相应增大。模拟结果揭示的规律与实验结果相一致。该研究有助于改进缩径工艺,提高加工效率。     

计算机仿真技术在CPU散热器设计的应用研究

CPU芯片的散热对其是否能够正常运作起到关键作用,因此对CPU散热的研究有着重要的意义.目前强迫风冷CPU散热器是最为常用的一种散热方法.通过建立CPU散热时的传热学模型,并基于有限元原理,利用计算机仿真软件Ansys对CPU散热器进行设计.实际测试结果表明,仿真结果误差较小,能较真实地反映散热器的散热情况.