The intermittent nature of solar radiation requires a thermal energy storage (TES) system for reducing the mismatch between energy demand and supply. Solar water heating (SWH) systems can help save up to 90% of the utilized energy for water heating. In this study, a compound parabolic concentrator (CPC) solar collector has been coupled to three different configurations of TES system. A comprehensive analysis on the effects of PCMs arrangements in TES systems viz three PCMs (case 1) and five PCMs (case 2) on the energy efficiency, exergy efficiency, and overall loss coefficient of the solar collector and TES system has been made and compared with sensible TES system. An experimental data showed an augmented energy storage of 12% and 41% in "case 1" and "case 2" over sensible TES system as a result of reduction in heat losses with the cascaded arrangement of PCMs. The collector paired with case 2 configuration clearly exhibited a higher exergy efficiency due to supply of heat transfer fluid at relatively lower temperature while compared to other TES configurations. The outcomes of this study reveal the key role of cascaded arrangement of PCMs for enhancing energy and exergy efficiencies of solar collector.
Keywords: Cascaded thermal energy storage; Compound parabolic concentrator; Exergy efficiency; Phase change material; Thermal resistance.
© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.