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化工进展  2015 

微细通道内CO2沸腾换热与干涸特性

DOI: 10.16085/j.issn.1000-6613.2015.08.009, PP. 2961-2966

Keywords: 二氧化碳,微通道,沸腾换热,临界热流密度,干涸,微尺度

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Abstract:

CO2作为一种天然制冷剂在微通道内应用具有很大的换热优势,然而由于微尺度效应及其物性,在低干度区容易发生干涸,严重影响换热效果。为研究微细通道内CO2流动沸腾换热与干涸特性,搭建了相应实验装置,对内径分别为1mm、2mm、3mm以及内表面粗糙度为16μm的不锈钢管,在CO2制冷剂热流密度2~34kW/m2、质量流率50~1350kg/(m2·s)、饱和温度-10~15℃下进行换热性能与干涸实验对比研究。结果表明常规管径换热特性在微细通道内不再适用;热流密度的增加对于强化核态沸腾换热具有显著影响,高于临界热流密度(criticalheatflux,CHF)则发生干涸;质量流率对于核态沸腾区换热系数的影响则较小;不同饱和温度时换热特性有所不同,高饱和温度下换热系数随其升高而提高,低饱和温度下则相反;干涸过程对总换热系数的影响占34%。研究结论为CO2微通道换热器的研究开发提供理论依据。

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