共查询到20条相似文献,搜索用时 15 毫秒
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本文针对余热利用中既需控制热源温度又需要对热量输入/输出进行管理的场合,提出了热管理器的概念.在运行过程中,热管理器可以实现对热源温度的控制,并根据各个用热对象的级别及工况,通过不凝性气体体积的变化,自动实现对热量输出的分配.为了验证热管理器的可行性,本文建立了实验样机及系统.实验结果表明,加热功率从6.0kW上升至14.0 kW,工质蒸汽温度的变化幅度仅为0.7℃.工质蒸汽/不凝性气体的交界面起到了良好的"热开关"作用.从热源回收的热量,按照优先级顺序依次分配给各个热用户. 相似文献
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1引言在过冷态超流氦(HellP)被成功地获得并应用在超导磁体冷却后,超流氦的工程应用引起了低温工程和低温物理研究者的重视,各种各样的HellP制冷机(恒温器)相继出现。同时出现了很多有关Hell浴中传热的论文山;然而从未有过有关压力对传热影响的系统研究。本文以Hell传热的基本规律及Hell的相图为基础,结合传热实验结果系统地研究了压力对Hell传热的影响。2P<PA时Hell中的最大临界热负荷软2·1饱和态起流氧2·1·1无噪声沸腾Hell传热中试样达到其最大临界热负荷伽的前提条件是必须克服一过冷度凸Tin。x。如图1氦的相图所示,… 相似文献
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本文提出了考虑过冷态超流氦传热中的He/Hell、GHe/Hel的二步相变传热模型,该模型与实验结果符合得很好。 相似文献
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Carbon foams are being developed as a new class of thermal management materials. These foams are produced with a wide variety of thermo-mechanical properties; however, very few studies of the properties of carbon foams have been reported in literature. This article reports on an experimental study that was conducted to determine the thermal conductivity of various forms of graphitic carbon foam by using the flash diffusivity and guarded hot plate method. To reduce errors introduced by porous specimen, the test samples were vacuum infiltrated with epoxy. The thermal diffusivity results from the flash diffusivity instrument were used to determine the thermal conductivity of the samples. Some foam samples were determined to have large variations in thermal properties within the sample block. A theoretical and numerical model has been used to examine the effect of the filler epoxy on the experimental results and the influence of pore characteristics on the thermal conductivity of these foams. It was determined that accurate measurement of thermal properties of graphitic foam samples requires careful selection of sample size and measurement technique. 相似文献
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导热高分子/沸石复合物强化固体吸附热传导性能的研究 总被引:3,自引:0,他引:3
1引言固体吸附式热泵是一种以热能为动力的能量转换装置,在强调环境保护,避免破坏臭氧层的当前,吸附式热泵作为一种替代氯氟烃的制冷供热系统,吸引了众多的研究者。但在研究进程中,各国研究者们遇到的共同问题是其固体吸附床传热传质速度太慢,从而引起吸附式热泵循环周期长,能量转换效率低。造成这种现象的主要原因是目前吸附床所采用的粉末多孔无机介质(沸石)的导热系数较低。为提高吸附剂的导热性能,意大利Cacciola[1]等人在吸附剂颗粒中加入铝粉或铁粉,但由于是物理混合,加入量较小,不能形成高导热的连续相,总… 相似文献
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温室覆盖材料的热学性质 总被引:1,自引:0,他引:1
结合理论与实验,本文对温室内常用的几种覆盖材料的热学性质进行了研究。通过实验测试了不同材料的全辐射透射率,在一些大型温室中进行了温室太阳辐射的实验研究。在实验的基础上,对温室内外的太阳辐射强度进行了模拟。应用传热学基本原理,在合理假设的基础上,对温室覆盖材料的传热系数进行了模拟。 相似文献
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金属蜂窝结构的稳态热性能 总被引:2,自引:0,他引:2
采用MCM、FVM方法数值模拟金属热防护系统蜂窝内辐射导热耦合换热,研究了一正六角形蜂窝的稳态热性能及其影响因素,定量分析了各种热量传递机制的作用.结果表明,金属蜂窝表面辐射换热和侧壁导热是主要热量传递方式,对所研究的蜂窝结构,在750 K以上蜂窝内表面辐射换热成为热量主要传递方式. 相似文献
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等热流条件下潜热型功能热流体换热强化机理研究 总被引:12,自引:0,他引:12
本文分析了潜热型功能热流体强化换热的物理机制,并基于等效比热模型,对等热流条件下圆管内该类流体层流流动换热强化的各因素进行了敏感性分析.同时,改进了内部流动传统的Nμ定义,使之能更有效地表征功能热流体换热强化程度 相似文献
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用高温应变计和热偶计等诊断技术,研究连续波氧碘化学激光(CW/COIL)与铝合金板作用产生的激光热应力。当照射靶面激光强度约1 000 W/cm2时,激光热应力随靶厚的增加而快速减小。当激光辐照靶材厚度h=1.00 mm、激光强度I=640~980 W/cm2时,激光热应力随辐照靶面激光强度的增加而增大。两者的激光热应力-时间曲线随靶厚的减薄或随辐照靶面激光强度的增加而变得越来越复杂。当靶厚h≤2.50 mm,辐照靶面激光强度I≥800 W/cm2时,激光热应力强度超过激光辐照区材料断裂强度,萌生许多孔洞裂纹,引起材料断裂破坏。 相似文献
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This article describes an experimental procedure conducted to estimate and investigate the transient thermal contact conductance (or thermal contact resistance) between the electrodes and workpieces during resistance spot welding. A fine thermal metrology was developed to collect thermal histories near the welding region. Indeed, the electrode tip was instrumented with several interior microthermocouples for measuring the transient temperature response during the welding process. A simple mathematical model, using an inverse heat transfer method, was built for the estimation of the transient heat transfer coefficient from interior transient temperature measurements. A simple resistance welding case of two steel sheets was investigated. The initial transient values of thermal contact conductance were found to be in agreement with those observed in the dry copper–steel solid contact case. At the end of the process, the transient heat transfer coefficient reaches a high value corresponding to the best heat transfer phenomenon at the interface during the welding process. When the metal is melted, the contact quality increases due to the high-applied electrode force. Higher electrode force and heating temperatures produce lower thermal contact resistance. The results obtained show the capabilities and the power of the coupled thermal metrology and transient inverse technique developed to investigate thermal history of resistance spot welding. 相似文献