抄録
A simplified formula for calculating effective transmission-absorption factor for the tube of evacuated tubular collectors is presented in the present paper. It is culculated from the index of refraction and the attenuation factor of the glass, the abrorptance of the absorber, and coefficients for the absorber character. The results by this formula are compared with results by ray-tracing due to validate the accuracy. By using this formula, effective transmission-absorption factors under various solar spectrums are calculated. The result shows the performance of evacuated tubular collector under direct solar spectrum is so different from that under diffuse solar spectrum that the difference between the performance under direct and diffuse solar radiation should be considered when the performance under natural solar spectrum is calculated. And brief coefficients sets for this formula for various feature's evacuated tubes are presented.
