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