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DSG槽式真空集热管内金属泡沫强化传热的数值研究

, PP. 83-89

Keywords: 直接蒸汽发电,太阳能,真空集热管,金属泡沫,强化传热,数值模拟

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Abstract:

以实际辐照为热边界条件,在实际工况下,对槽式太阳能直接蒸汽发电(directsteamgeneration,DSG)系统过热段的真空集热管内填充金属泡沫强化传热进行三维数值模拟。分析布置方式、几何尺寸H、金属泡沫孔隙率?对强化传热性能及管壁最大周向温差的影响。结果表明:布置方式和?一定时,H对集热管传热性能影响很大;布置方式和H一定时,?对传热性能影响较小;H和?一定时,底部和顶部布置对强化传热性能有较大影响。H=0.75且金属泡沫置于顶部时达到最佳热性能,与传统集热管相比,Nua提高1050%,管壁最大周向温差降低19℃;H=0.25且金属泡沫置于底部时达到最佳综合热性能,与传统集热管相比,Nua提高450%,管壁最大周向温差可降低25℃。部分填充金属泡沫的集热管,其管内、外壁面温度趋向均匀分布,且聚光区与非聚光区的平均温差大幅降低,这有利于降低管表面热应力而引起的管道变形。

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