太阳能腔式吸热器自然对流热损的数值研究

腔式吸热器是碟式太阳能热发电系统的一个重要组成部分,它的性能优劣直接影响到整个发电系统的效率。重点分析了腔式吸热器的自然对流热损,建立了6种典型腔式吸热器的二维模型,选用FLUENT6.3计算了在开口直径为10cm,壁温为400℃,倾角α=0°条件下的6种腔式吸热器的内部自然对流热损失。计算和比较发现,球形吸热器的内部对流热损比其他5种吸热器平均低10%。通过计算球形吸热器在不同Aw/Al(内表面积/开口面积)和不同倾角下的对流热损大小,发现球形吸热器的对流热损随倾角的增大而显著减小,在α=0°(开口朝侧面)时最大,α=90°(开口垂直向下)时最小;计算得到球形吸热器的最佳Aw/Al值为8～10。

Numerical investigation of natural convection heat loss in solar cavity receiver

Cavity receiver plays an important role in the dish solar thermal power system.Its performance can affect the efficiency of the whole system.In the present work,the 2-D-model of six typical cavity receivers are created and FLUENT6.3 is used to investigate the approximate estimation of the natural convection heat loss of the cavity receivers.The six typical cavity receivers are calculated at the same aperture diameter(10 cm),the same wall temperature(400 ℃),and the same inclination(α=0°).The result of the present numerical procedure shows that the natural convection heat loss from the spherical cavity receiver is approximately 10% fewer than that of the other five.The effect of AW/A1(inner surface area/aperture area) on the convection heat loss has also been studied for the spherical cavity receiver at different inclinations.The convection heat loss is maximum at 0°(cavity aperture facing sideways) and decreases monotonically with increase in angle up to 90°(cavity aperture facing down).The optimal AW/A1 for spherical cavity receiver ranges from 8 to 10.