Recent advances on the evacuated tube solar collector scrutinizing latest innovations in thermal performance improvement involving economic and environmental analysis

Abstract

Solar energy plays the most pivotal role in providing energy demand among all renewable energy resources in today's world. Hence, significant advances are being made to harness solar energy by using ever-evolving technologies such as solar collectors. Evacuated tube collectors have been in the center of attention due to high thermal efficiency and desirable performance in unfavorable weather conditions. This paper provides new insight into how ETSC has changed drastically to improve thermal performance. A full-scale comparison has been drawn between thermosyphon vacuum tube and flat plate units at the commencement to demonstrate the competency and uniqueness of evacuated tube collectors. At the next step, numerous numerical and experimental investigations have been compiled and presented to cover the latest innovations and developments in thermal modifications of evacuated tube collectors concerning the use of PCM, working fluids, and design parameters. Furthermore, to evaluate the thermal efficiency of collectors, mathematical modeling is also presented based on single-tube and the whole collector. Evacuated tube collectors have various residential and industrial applications for water heating, solar drying, solar desalination, and air conditioning which have been discussed extensively. In addition, challenges and obstacles in utilizing evacuated tube collectors have been identified and need to be tackled to reach higher thermal performance. Last but not least, an economic-environmental analysis is presented, which consequently demonstrated that evacuated tube collectors are cost-effective and impose less danger to the environment than flat plate collectors.