Abstract Solar air heater is a simple and convenient technology to utilize solar thermal energy. In this paper, an optimization study was carried out for a micro-heat pipe arrays-based solar air heater, aiming to derive the optimal operation conditions and geometrical parameters of the solar air heater. A 3-D CFD model was developed based on the physical heat transfer processes in the solar air heater and validated by the experimental results. The ambient temperature, air flow rate, air layer thickness, air duct aspect ratio and fins geometrical parameters (height and spacing) were selected as the parameters and their effects on the system efficiency and thermal-hydraulic performance of air flow were investigated. The results indicate that the inlet velocity of 3.3 m/s was determined to be the optimal flow velocity of the air heater, enabling a maximum thermal efficiency of 66.5%. The air layer thickness of 25 mm was determined as the optimal value, which is able to minimize the heat loss from the glass cover to the surrounding. The results also indicate the optimal aspect ratio, fin height and fin spacing among the values studied in the paper, which are 0.25, 12 mm and 6 mm, respectively.

中文翻译：

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基于微热管阵列的太阳能空气加热器性能优化数值研究

摘要 太阳能空气加热器是一种简单方便的利用太阳能热能的技术。本文对基于微热管阵列的太阳能空气加热器进行了优化研究，旨在推导出太阳能空气加热器的最佳运行条件和几何参数。基于太阳能空气加热器中的物理传热过程开发了 3-D CFD 模型，并通过实验结果进行了验证。选取环境温度、风量、风层厚度、风管纵横比和翅片几何参数（高度和间距）作为参数，研究了它们对系统效率和气流热工水力性能的影响。结果表明，3.3 m/s 的入口速度被确定为空气加热器的最佳流速，实现最高 66.5% 的热效率。空气层厚度为 25 毫米被确定为最佳值，这能够最大限度地减少从玻璃罩到周围的热量损失。结果还表明了本文研究的值之间的最佳纵横比、翅片高度和翅片间距，分别为 0.25、12 毫米和 6 毫米。