共查询到18条相似文献,搜索用时 93 毫秒
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多孔层在高于一个大气压下的沸腾两相流与传热 总被引:1,自引:0,他引:1
在前文[1]工作的基础上,利用微型多孔壁热虹吸管蒸发段模型,对粒状多孔层在高于一个大气压下的沸腾两相流与传热进行了分析;根据实验数据,建立了传热关联式。 相似文献
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1引言在过去的二十年中,已研制出诸如HighFI。、Thermoexcel-E、Ge、-T、CIT等多种高性能强化沸腾换热结构[‘-’],其中ThermoexcelE型结构是机械加工多孔层中有代表性的一种,并进行了较多研究*‘]。但迄今为止,研究工作多限于一个大气压时的沸腾工况[‘,’],而较少涉及非大气压时的情形。本文对一种ThermoexcelE型机械加工多孔层在大气压和高于大气压时的沸腾传热进行了实验,提出了简化物理模型,进行了流动与传热分析,综合实验数据,建立了相应的传热关联式。2实验研究实验装置参见文献*。多孔层基体为厚壁紫铜管… 相似文献
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本文报道了水向上流经垂直多孔介质同心套管混合对流的传热实验装置和进口段对流换热的实验结果.内装多孔介质的同心套管内热边界层的发展不同于空同心套管,多孔介质对流动的“扰动”明显地影响传热,在热边界层发展段的自然对流影响较大,且随着热边界层的发展其影响逐渐减小. 相似文献
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本文导出了垂直等热流壁前置以薄层高空隙率多孔介质条件下自然对流与辐射传热的控制方程,分别用数值和摄动方法求得了积分方程的数值解和零级、一级近似解.本文实验选用一层到三层不锈钢网作为多孔材料.实验表明,金属网显著地抑制了传热,网的层数、目数和间距对抑制传热的经济效果十分关键.理论所得的结果与实验吻合较好. 相似文献
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本文在前文工作的基础上,对高热负荷下粉末多孔表面上的沸腾传热提出了微型热虹吸管蒸发段模型,进行了气液两相流动与传热分析,并根据实验数据建立了半经验传热关联式。 相似文献
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木材微结构对其传热特性影响的实验研究 总被引:5,自引:0,他引:5
对落叶松和红松的试样进行了剖面结构的扫描电镜观察,图片显示在木材内部有非常明显而规则的多孔结构。通过实验测量了不同含水率的木材试样在20-200℃范围内的导热系数,并根据其多孔结构的特点对木材的传热特性进行了理论分析。结果表明,木材微结构的不同对其传热特性有显著影响,木材多孔部分在整个传热过程中起重要作用。木材的传热特性随着其多孔部分的孔隙分布和孔隙大小的不同而变化,在相同含水率的情况下,孔隙率高而孔隙小的木材传热能力较弱。 相似文献
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1引言微小空间内的沸腾在电子器件冷却、航天热控、微型换热器以及核反应堆的冷却等领域中有着广泛的应用,因此对其沸腾机理的研究具有重要的意义。过去微小空间内的沸腾研究主要是针对光滑表面[‘-‘1,已证明在微小空间里,沸腾换热受空间尺寸的影响要比大空间大。对于多孔表面在微小空间内的沸腾研究则相对较少。本文对矩形槽道表面和烧结型多孔表面在微小空间里的沸腾进行了实验研究。2实验装置实验装置如图1,实验段是3O0mm长的紫铜管(包括矩形槽道管和烧结型的多孔管),内插不同外径的不绣钢管,形成不同间隙的环形小空间。在内… 相似文献
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Experimental data on heat transfer and pressure drop in the case of forced-convection boiling in a channel with a porous matrix are presented. Correlations for the experimental data are given. Example calculation of thermohydrautic characteristics of a heat exchanger with a highly conductive porous matrix has been done using the obtained experimental data. Results of these calculations are presented. 相似文献
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Sarit K. Das G. Prakash Narayan Anoop K. Baby 《Journal of nanoparticle research》2008,10(7):1099-1108
Pool boiling heat transfer using nanofluids (which are suspensions of nano-sized particles in a base fluid) has been a subject
of many investigations and incoherent results have been reported in literature regarding the same. In the past, experiments
were conducted in nucleate pool boiling with varying parameters such as particle size, concentration, surface roughness etc.
and all sort of results ranging from heat transfer enhancement, deterioration and no effect were reported. This work tries
to segregate a survey on pool boiling of nanofluids with respect to particle concentration. This is due to the fact that a
major drift in heat transfer behavior is observed at higher and lower particle concentration. But upon deep perusal it has
been found that deterioration in heat transfer coefficient are mainly observed at higher particle concentrations (4–16% by
weight) and enhancements mainly at lower particle concentrations (0.32–1.25% by weight). Moreover, the relative size of the
particle with respect to the surface roughness of the heating surface seems to play an important role in understanding the
boiling behaviour. Also, recent works have reported that change in ‘surface wetting’ of the heating surface due to nanofluids
and the formation of a porous layer modifiying nucleation site density can be of importance in predicting nucleate pool boiling
characteristics of nanofluids. In the present paper, attempts are made to make systematic analysis of results in literature
and try to bring out a common understanding of the results in literature. 相似文献