Experimental investigation of improving received radiation by an hourly sun tracking on a weir-type cascade solar still

Abstract

This study considers improving received solar radiation by an hourly sun tracking on a weir-type cascade solar still (WTCSS). The system was adjusted for 6 hours in 6 steps. It included a dual-axis tracking system, with tracking axis fixed by adjustable tilt angles as the monthly optimum tilt angle. And the other one rotating in six hourly position tracking. The control unit was adjusted by Programmable Logic Controller (PLC) and Lab-TAB based on meteorological and geographical data collected for Ilkhchi city in the Northwest of Iran. Obtained results were compared those of the non-sun tracking system. The analytical results show that the daily maximum solar radiation was about 31.5 MJ/m2 in July. The experimental analyses show that received solar intensity on the tilted surface in sun tracking system was about 5 to 12% more than fixed azimuth angle and 10 to 30% higher than that of a horizontal surface. The daily maximum solar radiation (Ht) obtained in the summer months was between 0°and 25°. The highest values of the daily beam factor (Rb) belong to months December and January. The highest values of calculated hourly productivity for solar still belonged to July and Jun, with 1.1 and 1 kg/m2.h, respectively. Energy efficiencies of tracking system have increased significantly than the fixed system.