太阳能烟囱强化地下空间自然通风特性的研究

STUDY ON CHARACTERISTICS OF NATURAL VENTILATION STRENGTHENED BY SOLAR CHIMNEY IN UNDERGROUND SPACE

太阳能烟囱可利用太阳能诱导自然通风,是强化室内通风效果的一种有效方法。对太阳能烟囱强化地下空间自然通风的特性进行数值研究,建立结合竖直式太阳能烟囱的地下空间模型,并调查Rayleigh数(Ra)和烟囱宽高比对烟囱出口质量流率的影响。结果表明,不同烟囱宽高比条件下,烟囱出口处无量纲质量流率随Ra的增大而增大,当Ra达到某一数值后,其增长趋势变慢。不同Ra条件下,当Ra较小时(Ra=10^(3)~10^(6)),随着烟囱宽高比的增大,烟囱出口处无量纲质量流率先增大后减小,且曲线"极值点"处所对应的烟囱宽高比随Ra的增大而减小;当Ra较大时(Ra=10^(7)~10^(8)),烟囱出口处无量纲质量流率随着烟囱宽高比的增大而减小。分析结果得到,不同工况下,特定的Ra或烟囱宽高比条件会导致模型内部出现反向流,该现象会对烟囱出口处质量流率的变化规律造成影响。

Solar chimney has become an effective method to strengthen indoor ventilation.Therefore,the characteristics of natural ventilation induced by the solar chimney in an underground space is numerically investigated.Firstly,a model representing the underground space equipped with a vertical solar chimney is built.Then the influence of Rayleigh number(Ra)and chimney aspect ratio on the mass flow rate at the outlet are studied.The results show that with the increase of Ra,the dimensionless mass flow rate at the outlet increases for a certain aspect ratio,but its growth tends to decline when Ra exceeds a critical value.It is also found that,for a comparatively smaller Ra(Ra=10^(3)~10^(6)),the dimensionless mass flow rate at the outlet climbs up first and then declines with the aspect ratio increase,which leads to a peak value.And the corresponding aspect ratio for such peak value decreases as Ra increases.While,for a relatively larger Ra(Ra=10^(7)~10^(7)),the dimensionless mass flow rate at the outlet decreases when the aspect ratio grows.Moreover,the numerical results indicate that,the reverse flow will appear in the chimney for certain Ra or aspect ratio,which is a key factor to affect the mass flow rate.