Review of the impact of nanomaterial on the thermal efficiency of an evacuated tube solar air heater

The purpose of this review article is to analyse the use of nanomaterials to augment the thermal efficiency of an evacuated tube solar air heater (ETSAH). As a consequence of this, different varieties of nanomaterial are developed and utilized in the evacuated tube solar air heater. A comprehensive investigation is being carried out into both the incorporation of nanomaterials into the evacuated tube collector and the improvement in performance. During the course of this in-depth research, a number of issues have been investigated. One of these is how the enhancement of heat transfer is affected by the use of distinct nanofluid types, sizes, volume fractions, and applications in a variety of evacuated tube collector types. For the purpose of justifying and, ultimately, explaining the behaviors of nanomaterials for the purpose of thermal augmentation of evacuated tube collector, analyses have been performed and are being addressed here. Incorporating nanoparticles, as shown by an analysis of the relevant literatures, results in a substantial improvement in the thermal efficiency. From the literature survey, the heat pipe evacuated solar air heater tube using SWCNTs nanofluids was found to have a maximum enhanced efficiency of 93.43%.