Efficiency of thermal energy with evacuated vacuum tubes

This paper focused on the investigation of factors affecting the evacuated vacuum tubes performance under condition that the input energy was the incident solar radiation and the hot water's temperature was the output energy. The results showed that the hot water's temperature correlated linearly with the total cumulative incident solar radiation, with a coefficient of determination of 0.99, indicating a very linear relationship. It is possible to predict the volume and temperature of hot water from the total cumulative incident solar radiation, which had been recorded by the Department of Alternative Energy Development and Efficiency.