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首页> 外文期刊>Journal of Heat Transfer >Flow Boiling Heat Transfer,Pressure Drop, and Flow Pattern for C0_2 in a 3.5 mm Horizontal Smooth Tube
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Flow Boiling Heat Transfer,Pressure Drop, and Flow Pattern for C0_2 in a 3.5 mm Horizontal Smooth Tube

机译：3.5 mm水平光滑管中C0_2的流沸腾传热，压降和流型

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摘要

CO_2 flow boiling heat transfer coefficients and pressure drop in a 3.5 mm horizontal smooth tube are presented. Also, flow patterns were visualized and studied at adiabatic conditions in a 3 mm glass tube located immediately after a heat transfer section. Heat was applied by a secondary fluid through two brass half cylinders to the test section tubes. This research was performed at evaporation temperatures of - 15℃ and -30℃, mass fluxes of 200 kg/m~2 s and 400 kg/m~2 s, and heat flux from 5 kW/m~2 to 15 kW/m~2 for vapor qualities ranging from 0.1 to 0.8. The CO_2 heat transfer coefficients indicated the nucleate boiling dominant heat transfer characteristics such as the strong dependence on heat fluxes at a mass flux of 200 kg/m~2 s. However, enhanced convective boiling contribution was observed at 400 kg/m~2 s. Surface conditions for two different tubes were investigated with a profilometer, atomic force microscope, and scanning electron microscope images, and their possible effects on heat transfer are discussed. Pressure drop, measured at adiabatic conditions, increased with the increase of mass flux and quality, and with the decrease of evaporation temperature. The measured heat transfer coefficients and pressure drop were compared with general correlations. Some of these correlations showed relatively good agreements with measured values. Visualized flow patterns were compared with two flow pattern maps and the comparison showed that the flow pattern maps need improvement in the transition regions from intermittent to annular flow.
机译：给出了3.5 mm水平光滑管中的CO_2流动沸腾传热系数和压降。同样，在绝热条件下，在紧接传热段之后的3 mm玻璃管中观察并研究了流动模式。二次流体通过两个黄铜半圆筒将热量施加到测试段管上。这项研究是在-15℃和-30℃的蒸发温度，200 kg / m〜2 s和400 kg / m〜2 s的质量通量以及5 kW / m〜2到15 kW / m的热通量下进行的蒸气质量从0.1到0.8约为2。 CO 2的传热系数表明了核沸腾的主要传热特性，例如在200 kg / m〜2 s的质量通量下对热通量的强烈依赖性。然而，在400 kg / m〜2 s时，对流沸腾作用增强。用轮廓仪，原子力显微镜和扫描电子显微镜图像研究了两个不同管的表面条件，并讨论了它们对热传递的可能影响。在绝热条件下测得的压降随着质量通量和质量的增加以及蒸发温度的降低而增加。将测得的传热系数和压降与一般相关性进行比较。其中一些相关性与测量值显示出相对较好的一致性。将可视化流型与两个流型图进行了比较，比较表明，流型图在从间歇流到环形流的过渡区域中需要改进。

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  • 来源
    《Journal of Heat Transfer》 |2009年第9期|16-27|共12页
  • 作者

    Chang Yong Park; Pega Hrnjak;

  • 作者单位

    School of Mechanical Design and Automation Engineering,Seoul National University of Technology,172 Gongneung-2Dong,Nowon-Gu,Seoul 139-743, Korea;

    Department of Mechanical Science and Engineering,University of Illinois at Urbana-Champaign,1206 West Green Street,Urbana, IL61801;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    CO_2; low temperature; heat transfer; pressure drop; flow patterns; surface condition;

    机译：CO_2;低温;传播热量;压力下降;流型;表面状况;

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