Influence of heat enhancement technique on the thermal performance of solar water heater for sustainable built environment. Start-of-the-art review

Solar water heater (SWH) is important and low-cost technology for transforming solar radiation into heat energy that is utilized for commercial and industrial purposes. However, due to different advantages, this technology still suffers from poor thermal efficiency and thermal losses from the collector. The various reasons responsible for the poor heat transfer rate of SWH are heat losses from the system and different geometrical shapes of hindrance promoters. The researcher is working on various innovative methods to ameliorate the effectiveness of solar water heating systems (SWHS) by using various heat enhancement methods. The solar thermal conversion efficiency is found to be 70% as compared to solar electrical direct conversion system, which is around 17%. The different heat enhancement techniques, like twisted tape turbulator and their shape, etc., play a very remarkable role in ameliorating the effectiveness of SWHS. This review work abridges the previous research work with different heat enhancement techniques, including the coating effect of pipes, collector design, use of PCM, and different geometrical shapes of turbulence promoters. The twisted tape provides better eta as compared to other heat enhancement techniques.