Performance of a flat-plate solar thermal collector using supercritical carbon dioxide as heat transfer fluid

Abstract

Energetic and exergetic performance analyses of flat-plate solar collector using supercritical CO2 have been done in this study. To take care of the sharp change in thermophysical properties in near critical region, the discretisation technique has been used. Effects of zonal ambient temperature and solar radiation, fluid mass flow rate and collector geometry on heat transfer rate, collector efficiency, heat removal factor, irreversibility and second law efficiency are presented. The optimum operating pressure correlation has been established to yield maximum heat transfer coefficient of CO2 for a certain operating temperature. Effect of metrological condition on heat transfer rate and collector efficiency is significant and that on heat removal factor is negligible. Improvement of heat transfer rate is more predominant than increase in irreversibility by using CO2. For the studied ranges, the maximum performance improvement of flat-plate solar collector by using CO2 as the heat transfer fluid was evaluated as 18%.