共查询到18条相似文献,搜索用时 265 毫秒
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研究了替代工质R134a在沸腾温度为304.8K时,在光滑管管束和机械表面多孔管管束外的池沸腾换热性能,并探讨了其换热机理。研究结果表明,R134a在光滑管管束外的池沸腾存在明显的管束效应,而在机械加工表面多孔管管束外沸腾无管束效应出现,在相同热流密度下管束的各排管的沸腾传热系数均低于其单管值。 相似文献
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实验研究了水平单管管外沸腾以及二排、三排、六排管束的沸腾传热特性。结果表明,管束下排管热负荷大小影响上排管的沸腾传热系数。上排管的传热系数不仅取决于本身热负荷的大小,也和下排管或下几排管的热负荷大小有关。 相似文献
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实验研究了热通量为0.1~160 kW·m-2时,去离子水在光管及烧结型多孔表面管管外的池沸腾传热特性,分析了换热管布置方式(垂直与水平)、管径大小(20、25和32 mm)与多孔层颗粒尺寸(30~105 μm)对池沸腾传热特性的影响规律。结果表明:去离子水在多孔管表面的起始沸腾过热度小于光管,比光管低3 K左右;多孔表面管可明显强化核态沸腾传热,其沸腾传热系数可达光管的3~4.5倍;大热通量下,换热管水平布置时的传热效果较垂直布置佳,且布置方式对多孔管换热效果的影响比对光管的影响小;随管径增大,光管与多孔表面管的沸腾传热系数降低;大颗粒尺寸多孔层的强化效果优于小颗粒尺寸多孔层。 相似文献
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表面多孔管降膜沸腾传热研究 总被引:2,自引:1,他引:2
测试了第一二代机械加工表面多孔管的单管降膜沸腾传热性能。对JK-1管和JK-2管的降膜沸腾强化传热机理作了定性分析,并根据实验数据建立了简单的经验关联式。 相似文献
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测度了甲醇在9根第二代机械加工表面多孔管(JK-2管)、1根第一代机械加工表面多孔管(JK-1管)和1根光滑管上的单管饱和池沸腾传热系数,结果表明,JK-2管比JK-1管能更有效地强化甲醇的池沸腾传热。提出了一个简化的池核沸腾强化传热机理,并导出了相应的池核沸腾强化的传热关联式,该关联式与实验数据吻合良好。 相似文献
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丙烷作为自然工质具有良好的换热性能并且对环境影响较小,是替代传统制冷剂的选择。目前对于丙烷在螺旋管中沸腾传热的研究较少。实验测量了丙烷在管内径8 mm、螺旋半径42 mm、螺距21.5 mm的螺旋管中的流动沸腾传热系数。实验采用套管的形式,在螺旋管外用恒温水对丙烷进行加热,调整水入口温度与水流量得到不同的热通量。实验表明,螺旋管对流动沸腾换热具有一定的强化作用。实验数据与已有的螺旋管流动沸腾换热关联式进行了比较,在6 kW·m−2以下的低热通量时,Guo(1998)换热关联式比Ji(2015)预测准确度更高,推荐使用Guo(1998)关联式。 相似文献
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An experimental study was performed for the boiling heat transfer enhancement of water/salt mixtures on both plane and roll‐worked enhanced tubes in compact staggered tube‐bundle evaporators under atmospheric and increased pressure conditions. The effects of tube spacing, position of tubes, test pressure and salt‐water concentration on the boiling heat transfer characteristics in restricted spaces of compact tube bundles consisting of plane and roll‐worked tubes were investigated. The experimental results indicate that the single roll‐worked tubes in a bulk liquid have a greater boiling heat transfer promotion than the single plane tubes. For the plane tubes in compact tube bundles, the effect of tube spacing on the boiling heat transfer is very significant. The boiling heat transfer has a maximum enhancement when the optimum tube spacing is selected. For the roll‐worked tubes in compact bundles, the effect of tube spacing on the boiling heat transfer is also significant as the tube spacing is small. The boiling heat transfer still has a maximum value and a compound enhancement effect of the boiling heat transfer from both the optimum tube spacing and the surface treatment is observed for the enhanced tube bundles. 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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In order to optimize the design of the submerged combustion vaporizer(SCV), an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV. Several experiments were conducted using water and CO_2 as the heat transfer media in the tubes, respectively. The results indicated that hot air flux, the initial liquid level height and the tube pitch ratio had great influence on the heat transfer coefficient outside the tube bundle(ho). Finally, the air flux associated factor β and height associated factor γ were introduced to propose a new hocorrelation. After verified by experiments using cold water, high pressure CO_2 and liquid N_2 as heat transfer media, respectively, it was found that the biggest deviation between the predicted and the experimental values was less than 25%. 相似文献