Influence of dust on the thermal performance of all-glass evacuated solar collector tube

The accumulation of dust will constantly lead to the decline of the thermal performance of all-glass evacuated tube. To confirm the influence of dust on the all-glass evacuated tube, the article analyzed the relationship between temperature difference and accumulation of solar radiation for different tubes in this experiment. After the horizontally and 45° placed evacuated tubes were full of water and solarized for 30 days, then placed four tubes in 30°, 42°, 45° and 50° tilt angle and cleaned the surface of each tubes after solarizing 30 days. The tested results showed that the ability of heating water was declined by the accumulation of dust. In the same accumulation of solar radiation, for the same tube of horizontally and 45° placed, the quantityies of heat were declined by 0.98×104 J and 5.24×104 J, which respectively accounted for 2.11% and 10.25% of the total quantity of heat; one month later, 30°, 42°, 45° and 50° tilt angle tubes’ quantities of heat were declined by 13.8×104, 4.91×104, 5.90×104 and 6.22×104 J, separately, which respectively accounted for 29.83%, 10.99%, 12.75% and 11.90% the total quantity of heat. The results show that the influence of dust on the evacuated tube was the most significant in 30° tilt angle, then in 50°, 45°and 42° tilt angle.