Efficiency of evacuated solar tube collector

Abstract

In this work the performance of evacuated solar tube collector is investigated. The heat gained by this collector was found at the duration from 18/10 up to 21/10/2010. The maximum temperature for each day was found to be, (73ﾟc, 84ﾟc, 90ﾟc, 80ﾟc). at (17:30, 17:00, 17:00, 17:00) O’ clock. While the minimum values are (23ﾟc, 48ﾟc, 45ﾟc, 36ﾟc) at (10:00, 9:00, 9:30, and 9:30) O’ clock). The maximum efficiency is (79%, 70%, 71%, 86%) at (17:30, 17:00, 17:00, 17:00) O’ clock. The minimum efficiencies for each day are (18%, 13%, 12%, 16%) at (10:00, 9:00, 9:30, 9:30, 9:30) O’clock, respectively the variation of efficiency from day to day may be attributed to the variation of whether due to the presence of clouds and dust. The empirical relation between the efficiency and the temperature change per incident radiation watt is found to be linear which is in conformity with the theoretical relative.