NANOFLUIDS: LOOKING FOR MORE EFFICIENCY IN SOLAR HEATING SYSTEMS

Abstract

Researches into the use of solar energy and its application in the form of heat have been intensified in the recent history of renewable energy. However, flat plate and evacuated tube solar collectors still have low capacity to convert solar energy to thermal energy due to several factors, including low thermal conductivity of the exchange fluid. Recent studies seek to make feasible the use of nanofluids, whose thermophysical properties, such as thermal conductivity, can improve the performance of solar collectors. The objective of this paper is to review the recent literature on solar water heating systems, identifying opportunities to apply nanofluids to solar collectors, in order to increase their efficiency. The results of the research point to gains of more than 20% in the efficiency of the collectors compared to the use of water as thermal exchange fluid, and also indicate that the carbon nanoparticles have the best cost-benefit ratio, although the nanofluids are not yet feasible for real applications, because there are challenges to be overcome by this technology, such as reducing the loss of stability, which reduces its useful life, reduce the complexity and cost of production for commercial scale production. It is concluded that there is in fact potential to apply nanofluids in solar thermal systems.