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提出一种内置式PV-Trombe墙结构,并运用CFD技术对垂直入口内置式PV-Trombe墙在宽度变化时的自然通风和对流换热进行数值模拟。结果表明,烟囱内气流的温度与速度沿着烟囱通道宽度的方向变化很不均匀。在太阳电池表面存在一个空气温度和速度边界层,使得局部的温度梯度和速度梯度较大。烟囱的通风量随着宽度的增加先逐渐增加到一个极大值,然后随宽度的继续增加而减小。对于该文模型,获得最大通风量的最佳的烟囱的宽度与高度的比为(d/H)_(opt)=1/5。随着宽度的增加,烟囱的自然对流换热增强,空气对电池表面的冷却效果得到改善,因而PV的发电效率略有增加。对多组条件下的计算结果进行多元线性拟合,得到表征通风量与传热特性的无量纲参数Nu数、Re数随Ra*变化的拟合公式,为自然通风设计提供依据。
A built-in PV-Trombe wall structure is proposed and CFD technology is used to simulate the natural ventilation and convective heat transfer of the vertical PV-Trombe wall when the width changes. The results show that the temperature and velocity of the airflow in the chimney vary very unevenly along the width of the chimney channel. There is a boundary layer of air temperature and velocity on the surface of the solar cell, which makes local temperature gradient and velocity gradient larger. The chimney ventilation increases gradually to a maximum with increasing width and then decreases as the width continues to increase. For this model, the ratio of width to height for the best chimney to get the maximum ventilation is (d / H) _ (opt) = 1/5. As the width increases, the natural convection of the chimney increases, and the cooling effect of the air on the surface of the battery is improved. As a result, the power generation efficiency of PV slightly increases. Multiple linear fitting was made to the calculation results under multiple conditions to get the fitting formula of dimensionless number Nu number and Re number with Ra * that characterize the ventilation rate and heat transfer characteristics, which provided the basis for natural ventilation design.