Temperature analysis for the point-cell source in the vapor deposition process

The information indicating device plays an important part in the information times. Recently, the classical CRT (Cathod Ray Tube) display is getting transferred to the LCD (Liquid Crystal Display) one which is a kind of the FPDs (Flat Panel Displays). The OLED (Organic Light Emitting Diodes) display of the FPDs has many advantages for the low power consumption, the luminescence in itself, the light weight, the thin thickness, the wide view angle, the fast response and so on as compared with the LCD one. The OLED has lately attracted considerable attention as the next generation device for the information indicators. And also it has already been applied for the outside panel of a mobile phone, and its demand will be gradually increased in the various fields. It is manufactured by the vapor deposition method in the vacuum state, and the uniformity of thin film on the substrate depends on the temperature distribution in the point-cell source. This paper describes the basic concepts that are obtained to design the point-cell source using the computational temperature analysis. The grids are generated using the module of AUTOHEXA in the ICEM CFD program and the temperature distributions are numerically obtained using the STAR-CD program. The temperature profiles are calculated for four cases, i.e., the charge rate for the source in the crucible, the ratio of diameter to height of the crucible, the ratio of interval to height of the heating bands, and the geometry modification for the basic crucible. As a result, the blowout phenomenon can be shown when the charge rate for the source increases. The temperature variation in the radial direction is decreased as the ratio of diameter to height is decreased and it is suggested that the thin film thickness can be uniformed. In case of using one heating band, the blowout can be shown as the higher temperature distribution in the center part of the source, and the clogging can appear in the top end of the crucible in the lower temperature. The phenomena of both the blowout and the clogging in the modified crucible with the nozzle-diffuser can be prevented because the temperature in the upper part of the crucible is higher than that of other parts and the temperature variation in the radial direction becomes small.     

Temperature analysis for the linear cell in the vapor deposition process

The OLED (Organic Light Emitting Diodes) display recently used for the information indicating device has many advantages over the LCD (Liquid Crystal Display), and its demand will be increased highly. The linear cell should be designed carefully considering the uniformity of thin film on the substrate. Its design needs to compute the temperature field analytically because the uniformity for the thin film thickness depends on the temperature distribution of the source (organic material). In the present study, the design of the linear cell will be modified or improved on the basis of the temperature profiles obtained for the simplified linear cell. The temperature distributions are numerically calculated through the STAR-CD program, and the grids are generated by means of the ICEM CFD program. As the results of the simplified linear cell, the temperature deviation was shown in the parabolic form among the both ends and the center of the source. In order to reduce the temperature deviation, the configuration of the rectangular ends of the crucible was modified to the circular type. In consequence, the uniform temperature is maintained in the range of about 90 percent length of the source. It is expected that the present methods and results on the temperature analysis can be very useful to manufacture the vapor deposition device.     

基于流固耦合传热的摩托车发动机冷却水套优化设计

建立了摩托车发动机缸体与水套流固耦合传热仿真模型,进行了流体与固体之间的共轭传热仿真。结果表明,水套对缸体的散热效果基本满足散热要求;但缸体缸套区域水套内的冷却水流速分布较差,存在比较大范围的漩涡和流动死区,导致缸套局部过热,周向温差过大,为此对分水孔进行了优化设计,基本消除了流动死区,显著提高了水套冷却效能,缸体主要区域的温度显著减低,缸套局部过热也得到很大缓解。     

金属基复合材料差压浸渗凝固装置的设计

在分析金属基复合材料差压浸渗凝固原理的基础上设计差研制了新型金属基复合材料着压浸渗固装置，讨论充型压力、充型速度、预测件预热温度、浇注温度等工艺参数对铸造金属复合材料质量的影响。并指出各种参数值的选择范围。     

镁合金熔炉坩埚瞬态传热与热应力分析

针对镁合金熔炉坩埚使用寿命较短,坩埚各接合处易变形开裂而失效,采用有限元分析方法,对镁合金熔炉坩埚升温过程进行了瞬态传热模拟分析,得到了其升温过程曲线和温度场分布云图,并与实验采集的数据进行对比;在此基础上进行热—结构耦合分析,计算得出了升温结束时坩埚各接合处的热应力分布情况。分析结果显示:坩埚瞬态传热分析结果与实验数据吻合良好,说明瞬态传热分析真实可靠;坩埚各接合处热应力波动较大且局部有应力集中现象。     

太阳能热泵热水器加热性能的试验研究

在自行设计制作的试验台上进行了太阳能热泵热水器加热性能试验.定流量循环加热热水时,太阳能热泵热水器比普通太阳能热水器加热速度快3.4倍,集热器效率提高了1倍多.太阳能热泵直流式加热热水时,热水出口温度随热水流量的增加而降低,系统能效比随热水流量的增加而增加;热泵蒸发温度与热水入口温度越高,产生适宜出口温度的热水流量调节范围越大,出口温度相同时则系统能效比越高;太阳能热泵具有即时供热水功能.太阳能热泵热水器采用循环式加热比直流式加热耗时更短,经济性更好.     

Cooling of a heated surface with an impinging water spray

Several important parameters, such as liquid mass flux, droplet size distribution, droplet velocity, and heating target conditions (roughness and surface temperature) are involved in the industrial spray cooling heat transfer process. In this study, we investigated the effect of liquid mass flux, heating target roughness, and the droplet size on the droplet wall direct contact heat transfer in spray cooling phenomena. Three different conditions of surface roughness were investigated. The measurement of test surface temperature was performed using a non-intrusive method, i. e., using an infrared thermometer. The droplet size distribution of water spray was measured with Malvern 2600. The results indicated that the most influential parameters were the liquid mass flux and the surface roughness. The droplet size and the velocity played a less important role in the direct contact heat transfer because the interactions between droplets were very strong in a dense spray. The smooth surface showed the highest heat transfer among the surfaces tested. At high air pressure ([7] kPa), however, the degree of roughness did not affect much the heat transfer rate.     

还原炉挠性夹套的焊接残余应力有限元模拟

夹套是广泛运用在化工、医药等行业设备上的加热冷却装置,夹套焊缝是常常发生开裂泄漏的失效部位,焊接残余应力是导致开裂泄漏的重要因素之一。利用有限元技术对一种新型多晶硅还原炉挠性冷却夹套的焊接过程的温度场、残余应力和塑性应变场进行了数值模拟。借助ANSYS的APDL编程和单元生死技术,采用热-结构直接耦合法,传热分析采用含高斯热源的瞬态过程、应力分析为稳态,材料本构为随温度变化的双线性随动强化弹塑性模型。通过模拟获得焊缝区域残余应力和塑性应变的分布规律,为同类夹套的焊接强度评定提供了有效方法。     

非均匀热流下功率模块微小通道热沉传热特性研究

针对飞行器大功率电动舵机伺服系统功率模块内各器件发热损耗不同引起温度不均的问题,开展非均匀热流下微小通道热沉传热特性分析。依据功率模块三相桥电路的实际构型和工作特点,在数值计算方法和网格无关性验证基础上,利用FLUENT建立多种结构微小通道热沉的数值模型,对冷却通道在高、低热流区的典型周向传热特性及热沉总体性能进行探讨。研究发现,相同通道截面下,各通道圆周方向壁温呈非均匀分布,但不同通道的相同位置处局部传热系数较为一致;对于等流通面积的变截面冷却通道,通道数量及结构对局部传热影响突出。非均匀热流分布和通道流向、通道构型相匹配有助于改善基底均温性,渐缩通道构型和小截面多通道构型强化传热优势明显,具有较低热阻和较好均温性。     

复合型真空多层绝热低温容器真空丧失后热响应研究

搭建了高真空多层绝热低温容器完全真空丧失研究实验台,分别利用干燥氮气及空气作为破空气源,进行了低温容器发生完全真空丧失事故后排放试验和无排放试验。排放试验中测得了复合型真空多层绝热低温容器在发生完全真空丧失事故后的排放率并计算了热流密度;无排放试验中测得了复合型真空多层绝热低温容器在发生完全真空丧失事故后的压力上升情况和液体的温度分层。试验结果表明,导入复合型真空多层绝热低温容器绝热夹层的气体种类对其完全真空丧失后的响应有很大的影响。     

A numerical study on the conjugate natural convection in a circular pipe containing water

In this paper, the effect of material property of pipe on the conjugate natural convection in a circular pipe containing water was investigated by solving the unsteady incompressible Navier-Stokes equations coupled with energy equations of the water and pipe. Natural convection and conduction of water inside the pipe was coupled with the conduction of the pipe whose bottom was subject to uniform heat source. From the present grid resolution and time-step independent solutions, it has been confirmed that the water temperature inside a PVC pipe was higher than that inside a steel pipe due to the smaller heat capacity of PVC and that the streamline patterns of the two cases were found to be opposite because the thermal diffusivity of steel (PVC) is larger (smaller) than that of water such that steel (PVC) pipe is heated faster (slower) than water. Furthermore, a quantitative comparison of heat flux to water was performed by examining the distributions of the heat flux along the inside walls of steel/PVC. The average temperature of water inside steel was found to be higher than that inside PVC at the initial stage of heating. On the other hand, PVC provided a larger heat flux to water when it reached a steady value.     

无机热管-真空管太阳能热水系统瞬态热分析

以无机热管-真空管太阳能集热器制成的太阳能热水系统为研究对象,在瞬态传热分析的基础上,推导出了总热损失系数、效率因子、热迁移因子和瞬时效率的理论表达式。通过自编程序,对该热水器在4个典型节气中每天的瞬态热参数变化,以及影响集水管内水温变化的因素进行了计算和分析。结果表明,太阳辐照量和水的质量流量对集水管中的水温影响较大,进水温度对集水管内水温上升曲线斜率的影响较小,但对水温影响较大。研究结果有助于指导该类热水器的设计及其操作性能的预测。     

水火弯板温度场理论分析和数值模拟

水火弯板工艺是船体外板弯曲的一项关键的流程,前人对钢板的温度场已进行过相关的研究。高斯热源热流密度模型被广泛用于水火弯板的温度场的分析,其参数的选取和定义,是水火弯板数值模拟中一个关键问题。本文采用高斯热源热流密度模型对水火弯板中的气体火焰热源和钢板的温度场展开了研究,并提出了高斯热源热流密度模型的不足和改进方法。     

Analysis of tool temperature fluctuation in interrupted cutting

A unidimensional model for temperature distribution in the tool during intermittent cutting is presented. The tool-chip interface heating is approximated by a periodic rectangular heat flux. The effects of cutting time ratio, frequency of temperature fluctuation and thermal diffusivity of the tool material on internal temperature distribution and on thermal stresses developed in the tool have been discussed. With increasing cutting frequency, the temperature gradient in the cutting zone increases, but with higher thermal diffusivity of the tool material, it diminishes. The magnitude of thermal stresses increases with increase in amplitude of temperature fluctuation     

热管废热回收蒸发器在浊水余热回收中的应用

针对污水的特性,为避免生活污水与热泵工质R22产生交叉污染,从而导致系统不能正常运行的可能性,提出在污水与热泵系统工质R22之间采用一个热管换热器,得出在系统增加了一个热管换热器的情况下,污水流量一定时,热泵制热量,性能系数COP值,热泵系统R22工质蒸发温度,污水废热回收热量随污水进口温度的增大而增大,其中热泵工质蒸发温度的增幅最大,达到65.79%,废热回收热量的增幅最小,为6.8%,污水入口温度一定时,热泵制热量,性能系数COP值,热泵工质蒸发温度,废水回收热量随着污水流量的升高而升高,但是热泵工质蒸发温度的和性能系数COP值的增幅减少,热泵制热量,热管工质蒸发温度以及废水回收热量的增幅缓慢增加.     

Quadratic curve heat flux distribution model in the grinding zone

In order to estimate temperature distribution and the influence of grinding parameters on grinding temperature in the grinding zone, a theoretical model used for calculating and simulating the grinding process must be established. Many simplified heat source models developed previously have some errors compared with the actual heat flux to the workpiece. Therefore, based on the triangular heat flux distribution model and temperature distributions measured, an inverse method for the heat transfer mechanism in the grinding zone was investigated and a quadratic curve heat flux distribution model was developed to determine the heat flux distribution and predict the surface temperature of the workpiece. From the theoretical expression of heat flux to the workpiece, it has been found that the quadratic curve heat flux is the superposition of square law heat flux, triangular heat flux, and uniform heat flux in the grinding zone. By comparison of theoretical analysis with the experimental results, it has been demonstrated that the solution using a quadratic curve heat flux can improve the grinding model by decreasing the error, although the uniform and triangular heat fluxes can explain the condition of the heat flux to the workpiece along the grinding zone.     

毛细管吊顶联合独立新风空调系统供暖室内热环境的试验研究

通过搭建毛细管吊顶加独立新风系统试验平台,测试了不同供水温度和供水流量下,毛细管吊顶的换热效果、室内空气垂直温度分布和围护结构温度分布;进一步,在毛细管吊顶联合独立新风系统运行工况下,测试了室内垂直温度分布和围护结构温度相应特性。试验测试结果表明,回水温度值越高,在测试时间内毛细管吊顶的平均换热量越大;供水流量值越大,毛细管吊顶换热量越大。毛细管吊顶单独供暖时,室内0.5到2m竖直高度方向存在2℃温差,吊顶不同测点最大温差在2℃左右。毛细管吊顶联合独立新风系统供暖时,室内竖向温度变化不明显,吊顶不同测点最大温差在1℃左右。     

发动机水套冷却性能分析

利用数值模拟对某汽油机的冷却水套进行了冷却性能研究,对原机冷却水套内冷却水的流场分布、冷却水套内壁面换热系数和压力损失进行了分析.计算结果表明:该汽油机冷却水套总体分布合理,设置的8个分水孔各自取到不同的作用;通过大孔B1、B2的流体用于冷却鼻梁区等重点区域,其它孔主要用来将绕流缸体的冷却水引入缸盖,对缸盖冷却起补充作...     

热泵热水器蓄热水箱的数值模拟与结构优化

利用ANSYS数值模拟软件中的ICEM和FLUENT模块对静态加热式热泵热水器蓄热水箱内温度场和速度场进行了模拟计算,研究分析了不同的盘管直径及位置对水箱内部速度场与温度场的变化的影响,在此基础上提出了一个有关于冷凝盘管结构改进的优化方案。     

干式地板辐射供暖系统特性的试验研究

对干式地板辐射供暖系统进行了连续供暖和变供水工况测试,分析和评价了干式系统的供暖性能和热舒适性,并与湿式系统进行了比较。试验结果表明:干式系统稳定运行时,室内空气温度在水平和竖直方向分布均匀,热稳定性和热舒适性好。辐射换热量约占总换热量的65.6%,总换热量能够满足大部分建筑冬季供暖需求。干式系统在35~40℃区间内调节供水温度,可明显改变室内温度,而调节供水流量对室内温度影响不大。与湿式系统相比,干式系统预热时间短,对供水温度要求低,供暖能力强,更适用于需要间歇供暖的场所,但其蓄热能力差。结果将为干式系统的设计及其应用提供试验数据支撑。