中文摘要：

对超临界压力下二氧化碳在微细管内（D =0.4 mm）的对流换热进行了模拟研究,分析了二氧化碳物性变化对浮升力和换热效率的影响,并拟合出考虑浮升力时,微细管内超临界二氧化碳对流换热关联式.结果表明：二氧化碳物性的变化对浮升力的影响较大,在临界点附近,二氧化碳物性的剧烈变化,引起浮升力出现较大的降幅,传热出现强化;回归的对流传热关联式,可以很好的预测微细管内超临界二氧化碳对流换热的性能.

英文摘要：

Convection heat transfer of supercritical pressure CO2 in microtubes （D =0.4 mm） were investigated,the changes of physical property of supercritical CO2 and the impact of buoyancy on the heat transfer were analyzed,and convection correlations of supercritical CO2 in microtubes were fitted when considering buoyancy.The results showed that the impact of physical properties of carbon dioxide on the buoyancy was big,and the physical property of CO2 changes very violently at the critical point,which caused larger decline of buoyancy,heat transfer was strengthened.It was also concluded that the heat transfer correlations of the supercritical CO2 were achieved,which can be used to predict heat transfer performance of supercritical CO2 in microtubes.