塔式太阳能吸热器曲面涂层吸收率测试方法研究

Research on measurement methods for curved surface coating absorption of tower solar absorber

吸热器涂层吸收率的准确测量对吸热器性能评估、优化具有重要意义。目前吸热器涂层吸收率的实验研究大多局限于平面金属基材。以塔式太阳能熔盐吸热器圆柱形吸热管为研究对象,提出蓝丁胶法和漫反射盒法2种广泛适用的测量曲面涂层吸收率测试方法。蓝丁胶法器材准备简单,操作复杂;漫反射盒法器材准备复杂,操作简单。2种方法在测量过程中隔绝环境光线干扰,得到各种涂层附着于平板和圆管表面的测量吸收率,通过不同涂层在平板和圆管上的吸收率对应关系建立拟合曲线,从而修正测量数据得到吸热管涂层吸收率,拟合曲线精确性R^(2)≥0.995;不遮光条件下直接测量2.5cm直径吸热管吸收率,最大相对误差为13.39%,使用蓝丁胶法和漫反射盒法后相对误差分别降为0.27%和0.45%,2种方法各点结果相对误差之差小于0.30%,测量过程中涂层吸收率越大,各因素对测量结果影响越小;在蓝丁胶测试方法中,吸热管直径越大,测得的吸收率越小。

The accurate measurement of solar absorber coating absorption is of great significance to the evaluation and optimization of the absorber performance.At present,the experimental researches of absorber coating absorption are mostly limited to the flat metal substrate.By taking the cylindrical tube of tower solar molten salt absorber,two widely used measurement methods for testing the absorption of curved surface coatings are proposed.The equipment preparation of Blu-Tack method is simple but the operation is complex,and the equipment preparation of diffuse reflection box method is complex but the operation is simple.The two methods isolate the interference of ambient light during the measurement process,and obtain the measured absorption of various coatings attached to the surface of plate and tube.The fitting curve is then established by the corresponding relationship between the absorption of different coatings on the plate and tube,so as to modify the measured data to obtain the absorption of the absorber tube coating.The results show that,the accuracy of the fitting curve R2≥0.995,the maximum relative error is 13.39%when the absorption of 2.5 cm diameter tube is measured directly under unshaded conditions,and the relative error reduces to 0.27%and 0.45%by using Blu-Tack method and diffuse reflection box method,respectively.The difference of the relative error of each point of the two methods is less than 0.30%.The greater the coating absorption,the less the influence of each factor on the measurement results.In the test method of Blu-Tack,the larger the tube diameter,the smaller the measured absorption.