A review on recent advancements in performance enhancement techniques for low-temperature solar collectors

Solar energy as a plentiful and environment-friendly source of energy has an acceptable potential in nearly most of the regions around the world. Thermal technologies are commonly used to provide heat requirements of different domestic, agricultural, residential, and industrial applications from the sun. This paper reviews thermal performance enhancement techniques of the most widely-used low-temperature solar collectors (LTSCs) including flat-plate collectors (FPCs), evacuated tube collectors (ETCs), and compound parabolic concentrators (CPCs) by introducing challenges and discussing future research potentials. In this regard, energy analysis of each collector type along with the latest advancements to boost the heat collection capability of the LTSCs reported in the previous studies is presented. The discussed methods in this study broadly cover structural modifications, absorber coatings, integration with reflectors, using alternative working fluids including nanofluids, and employing thermal energy storage (TES) systems. This comprehensive review is reflecting the level of technical maturity of each type of LTSCs and is expected to serve scientists, engineers, and developers with the latest achievements in this technology