Abstract One of the main factors affecting the heat transfer efficiency of solar collector is that the ordinary fluid in it is in the state of natural convection. Supercritical fluid is expected to improve the heat transfer efficiency of solar collectors due to its dramatic changes in thermal properties, so it is necessary to carry out the research of natural convection of supercritical fluid. Although researchers have made lots of related experimental investigations, heat transfer mechanism of supercritical natural convection is still unclear. In order to clarify its heat transfer mechanism, this article conducts a numerical analysis for supercritical natural convection applying lattice Boltzmann method, which has been proved to be valid and convenient. Considering the influences of temperature difference and pressure on natural convective heat transfer of supercritical fluid are seldom studied, the relevant researches are carried out in the article. The results imply that pressure of supercritical fluid in solar collectors should be less than 11 MPa so that high heat transfer performance can be obtained. Finally, the correlations of average Nusselt number, Rayleigh number, and pressure are fitted for the convenience of heat transfer calculation.

中文翻译：

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格子Boltzmann方法对超临界自然对流的数值分析

摘要 影响太阳能集热器传热效率的主要因素之一是其中的普通流体处于自然对流状态。超临界流体由于其热性质的剧烈变化，有望提高太阳能集热器的传热效率，因此有必要开展超临界流体的自然对流研究。尽管研究人员已经进行了大量的相关实验研究，但超临界自然对流的传热机制仍不清楚。为阐明其传热机理，本文采用格子Boltzmann方法对超临界自然对流进行了数值分析，结果证明该方法有效且简便。考虑到温差和压力对超临界流体自然对流传热的影响鲜有研究，文章进行了相关研究。结果表明，太阳能集热器中超临界流体的压力应小于11 MPa，才能获得高传热性能。最后，为了传热计算的方便，拟合了平均努塞尔数、瑞利数和压力的相关性。