摘要
真空管太阳能集热器的热性能检测应该以其实际接收的太阳辐照量为基准。然而,目前评定真空管太阳能集热器热性能的依据为集热器平面接收到的太阳辐照量,因此,现有检测方法得到的结果并不能反映真空管太阳能集热器的真实热性能。文章基于辐射计算的经验关系式构建了南北向真空管太阳能集热器(NSETC)日采光量的简化计算方法。计算结果表明:当真空管太阳能集热器安装倾角偏离当地纬度10°、方位角偏离正南20°以内时,基于简化计算方法和直接数值计算方法得到的Rb,t-s之间的相对偏差均小于2%;Rb的估算值与直接数值计算值之间的相对偏差小于2.2%;采用二维和三维天空辐射模型计算得到的真空管太阳能集热器天空辐射采光量之间的相对偏差小于0.65%;由太阳直接辐射简化计算方法结合二维天空辐射模型计算得到的真空管太阳能集热器年采光量,与直接数值计算结合三维天空辐射模型计算得到的年采光量之间的相对偏差小于1%。
The thermal performance of all-glass evacuated tube collectors(ETC)is usually evaluated based on daily irradiation fallen on the collector surface as the actual daily irradiation received by such collector is impossible to be directly measured.However,the irradiation actually received by ETC is quite different from that fallen on the collector surface,and this means that the current test method is not reasonable to evaluate the thermal performance of ETCs.In this work,a simplified method to estimate the daily beam radiation really received by NSETCs(Hb,t)is proposed by means of empirical correlations suggested by Collares-Pereira and Rabl.Analysis shows that when the deviation of tilt-angle of NSETC from the site latitude is less than 10°and deviation of the azimuth angle from the due south is less than 20°,the difference of Rb,t-s,the ratio of Hb,t to that received by the collector surface(Hb,s),estimated by the proposed method and that obtained by direct numerical calculations is less than 2%;and the difference of Rb,the ratio of Hb,t to daily beam radiation on the horizon,between estimated and numerically calculated is less than 2.2%.Results also indicate that the difference of collectible sky diffuse radiation on the NSETEC calculated based on 2-dimensional and 3-diemensional isotropic sky diffuse radiation models is less than 0.65%,and the difference of annual collectible radiation(Sa)estimated based on the simplified method and 2D sky radiation model and that obtained by direct numerical calculation together with 3D sky radiation model is less than 1%.
作者
吴茂刚
张有刚
唐润生
Wu Maogang;Zhang Yougang;Tang Runsheng(Solar Energy Research Institute,Yunnan Normal University,Kunming 650500,China)
出处
《可再生能源》
CAS
CSCD
北大核心
2021年第6期744-753,共10页
Renewable Energy Resources
基金
国家自然科学基金项目(51866016)。
