A practical study to improve the performance of solar water heater by changing the angles of the reflective mirrors

Solar radiation can be effectively converted into thermal energy and transferred to working fluids such as water or air for various residential and industrial applications. This study presents an enhanced approach for improving the performance of flat-plate solar thermal collectors in Kirkuk, Iraq, by integrating two adjustable reflective mirrors. These reflectors were used to concentrate both direct and diffuse solar radiation onto the collector surface, thereby increasing the overall absorbed energy. Experimental evaluations were conducted over four months: December ۲۰۲۴ and January, February, and March ۲۰۲۵. During December, the upper reflector angle was varied throughout the day to maximize incident radiation, while the lower reflector remained fixed at θ = ۵°. The optimal monthly upper mirror angles were determined to be ۲۵°, ۲۲°, ۲۰°, and ۱۸° for December through March, respectively. The results demonstrated significant improvements in thermal efficiency: ۹.۲۱% in December, ۳۲.۰۵% in January, ۸.۰۲% in February, and ۶۶.۶۶% in March compared with the conventional collector. The relatively lower efficiency gains observed in December and February were attributed to adverse weather and reduced solar intensity during those periods.

کلیدواژه ها:

Renewable Energy ، Flat plate solar collector ، Radiation intensity ، Reflective mirrors ، absorber plate ، solar thermal efficiency