Abstract Solar air collectors (SAC) convert the available solar energy into useful thermal energy for different heating applications such as drying, space heating, hot water etc. The study aims to enhance the thermal performance of a flat plate SAC by modifying the absorber surface. The experimental performance of two variant SACs (a sand coated absorber to increase surface roughness and a conventional plain absorber) was compared under controlled laboratory conditions The experimental tests were performed under a solar simulator for radiation levels of 400, 600, and 800 W/m2 and variable air mass flow rate ranging from 0.01 to 0.02 kg/s/m2. Results indicated that increasing the air flow rate by 90% enhanced the thermal efficiency on a plain absorber SAC by almost 68%, and the rate of increase was higher for the sand coated absorber. SAC with the sand coated absorber provided additional surface area resulting in an increase in the effective heat transfer. The thermal efficiency of the collector was improved by up to 17% for the sand coated absorber compared to the plain absorber. The absolute thermal efficiency of the SAC varied from 19% to 41% under the different tests conditions.

中文翻译：

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吸收器表面粗糙度对太阳能集热器性能的影响：实验研究

摘要 太阳能空气收集器 (SAC) 将可用的太阳能转化为有用的热能，用于不同的加热应用，如干燥、空间加热、热水等。该研究旨在通过修改吸收器表面来提高平板 SAC 的热性能。在受控实验室条件下比较了两种变体 SAC（用于增加表面粗糙度的砂涂层吸收器和传统普通吸收器）的实验性能 实验测试在太阳模拟器下进行，辐射水平分别为 400、600 和 800 W/m2和范围从 0.01 到 0.02 kg/s/m2 的可变空气质量流量。结果表明，将空气流量增加 90% 可使普通吸收器 SAC 的热效率提高近 68%，而砂涂层吸收器的热效率增加率更高。带有砂涂层吸收器的 SAC 提供了额外的表面积，从而增加了有效的热传递。与普通吸收器相比，涂砂吸收器的集热器热效率提高了 17%。在不同的测试条件下，SAC 的绝对热效率从 19% 到 41% 不等。