共查询到19条相似文献,搜索用时 46 毫秒
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本文综述了近十年来发表的有关混合物池沸腾、流动沸腾、降膜沸腾、管内外自然对流冷凝及强制对流冷凝传热研究的成果和现状,详述了混合工质沸腾,冷凝的现象、机理及其传热强化的方法,并对该领域的深入研究提出了新建议。 相似文献
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沸腾传热强化技术及方法 总被引:1,自引:0,他引:1
介绍了沸腾传热强化技术的方法,对影响沸腾传热强化的因素进行了分析,并对几种典型的工业用传热强化管及其性能做了介绍,最后对强化沸腾传热的研究方向进行了讨论。 相似文献
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多孔表面强化沸腾传热的研究进展 总被引:2,自引:0,他引:2
本文综述了多孔表面用于强化沸腾传热的研究工作。即介绍了多孔表面的形成和结构表征方法、多孔表面的沸腾传热性能以及描述多孔表面沸腾传热机理的物理和数学模型,同时分析了影响多孔表面沸腾传热性能的因素,探讨了多孔表面强化沸腾传热研究的发展方向。 相似文献
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引 言核状池式沸腾是一种成核现象 ,它包括气泡的产生、气泡的生长以及气泡的脱离 3个阶段 .在工程应用中 ,采用强化表面来获得较高的池式沸腾传热系数的例子已有许多 ,此种方法能在较小传热温差的情况下获得较大的传热通量 .例如在低品位热能的利用中就采用了这种方法 .另一个很有应用前景的领域是电子元件的冷却 .强化核状沸腾传热的方法有两种[1] ,一种是降低沸腾传热表面的润湿性 ,这可以通过在传热表面上涂覆低表面能材料如聚四氟乙烯来达到 ,但是这种方法又增加了传热的附加热阻 .另外 ,这种方法对于高润湿性的介质是不适用的 ,例如… 相似文献
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Based on the tests of more than ten different additives, several effective additives are found capable of improving the boiling heat transfer behavior of water pronouncedly. The mechanism of the enhancement of nucleate boiling with additives has been investigated, and the results indicate that one of the important reasons is that the nucleation sites have been increased. 相似文献
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The effects of electrode polarities on EHD enhancement boiling heat transfer were investigated theoretically and experimentally based on the analysis of electric field distribution affected by superheat boundary layer and charge injection. The results showed that electric field distribution was changed by the charge induced by temperature gradients in the superheat boundary layer, but the change was independent of electrode polarities. However, when electric charge injection occurred, the electrode applied positive high voltage might generate different characteristics of charge injection from that generated by applied negative high voltage. If the electric field on the surface of heat transfer increased due to charge injection, the augmentation effects would increase. The experiments demonstrated that positive high voltage gave larger enhancement factors than negative high voltage. The experimental phenomena could be interpreted well on the basis of charge injection characteristics. 相似文献
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<正>1 引言 随着对传热过程这一客观规律认识的深化以及加工制造技术的进步,人们已能研制开发出各式各样的强化换热元件,并在工程实践中取代传统的光滑管从而取得省材节能的双重效果。T.C.Canavos曾预言:到目前为止,强化换热元件的工作还仅仅是个开始,但是它的好处是那样地明显,以至于普通光滑管之被淘汰只不过是一个时间的问题了。多年来的实践证明这种预言是正确的,在强化换热元件中,强化液体泡核沸腾的元件的研究进展尤为突出,自60年代末期以后,先后有4种管型实现商品化,其中一种就是T形翅片管(Gewa-T)。T形翅片管自1978年问世于原联邦德国的Wieland Worke公司以后,国内外已有多项研 相似文献
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引言目前,卧式再沸器的热设计仍沿用Palen等人60年代初基于单管池沸腾传热机理所提出的方法.近十几年来,大量实验研究结果表明,在相同条件下管束的沸腾传热系数高于单管.人们逐渐认识到管束沸腾传热为核沸腾、对流和薄层蒸发传热机理所控制.由此可见,在卧式再沸器的设计中,基于单一的池沸腾传热机理所得关联式进行卧式再沸器的热设计,造成传热面积裕度偏大、设备体积庞大、浪费材料、设备效率低,显得十分保守.因此,深入研究水平管束的沸腾传热机理,进而发展更为合理的卧式再沸器的设计模型,对于改进这类设备的设计、改善设备… 相似文献
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The effect of a radial d.c. electric field on nucleate boiling heat transfer was investigated experimentally using a single-tube shell/tube heat exchanger. A dielectric liquid (Freon R. 114) was used in the shell and the tube was heated by circulating water through it.
It was found that the application of a sufficiently intense electric field to the boiling heat transfer surface resulted both in the elimination of boiling hysteresis and the enhancement of heat transfer for the range of superheat studied. An application of approximately 20 kV was more than sufficient to eliminate the hysteresis.
It was also observed that there appeared to be a transition between two situations. At lower superheat there is an appreciable improvement in the heat transfer coefficient due to both initial (0 to 10 kV) and incremental (10 to 20 kV) voltage increases. At higher superheat, however, the greater improvement (about four times) is obtained with the initial voltage application 相似文献
It was found that the application of a sufficiently intense electric field to the boiling heat transfer surface resulted both in the elimination of boiling hysteresis and the enhancement of heat transfer for the range of superheat studied. An application of approximately 20 kV was more than sufficient to eliminate the hysteresis.
It was also observed that there appeared to be a transition between two situations. At lower superheat there is an appreciable improvement in the heat transfer coefficient due to both initial (0 to 10 kV) and incremental (10 to 20 kV) voltage increases. At higher superheat, however, the greater improvement (about four times) is obtained with the initial voltage application 相似文献
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建立了带有气液分离器的高沸点有机工质流动沸腾换热实验台,对垂直上升多孔表面管内高沸点有机工质异丙苯的强化流动沸腾换热与阻力特性进行了实验研究,获得了传热系数与压降随干度的变化情况,并与光管内的实验结果进行了比较.另外,还通过实验得到了三个质量流速下的流动沸腾曲线.实验过程中质量流速范围为391~790kg8226;m-28226;s-1,实验工况干度范围为0.09~0.58,压力范围为0.16~0.31MPa.通过对实验数据的回归分析,获得了传热系数与摩擦压降的计算关联式.实验结果表明,多孔表面管在强化换热的同时,并没有使阻力增加很多,具有良好的应用前景. 相似文献