Thermal augmentation in evacuated tube solar collectors using reflectors, nano fluids, phase change materials and tilt angle: A review

Abstract

This review presents influence of reflectors, tilt angle, phase change materials and nanofluids in solar evacuated tube solar collectors (ETSCs). In order to increase efficiency, various designs of solar ETSCs have deduced that ETSCs integrated with reflectors are one of the most efficient and powerful designs. In order to increase the solar irradiation directed to the basin liner or the water as well as the efficiency of the ETSCs, the reflectors are a nice and cheap upgrade. Reverse flow rate (RWR) measured using water temperature measurements in solar tubes is dependent on collector tilt-angle. The RWR increases with increase in the collector’s tilt-angle. Phase change Materials (PCMs) has emerged as an option by serving as thermal storage batteries to increase the efficiency of the ETSCs. The presence of nanofluids with enhanced thermal, optical, and magnetic properties has become very common to efficiently use solar energy by converting it into thermal.