Chun-Man KanSih-Wei ChangJun-Yi LiJuan Carlos CisnerosHSUEN-LI CHEN2024-10-012024-10-012024-10-1513858947https://www.scopus.com/record/display.uri?eid=2-s2.0-85203266454&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/721676This study introduces a nitrate-salt-based direct absorption solar collector (DASC) for a photothermal energy harvesting system with efficient solar energy harvesting and the reduction of thermal radiation loss. Investigations of the optical properties of snow-like solid-state binary nitrate salt in solar and thermal infrared (IR) spectral regions were first conducted in this study. Research revealed that the solid-state binary nitrate salt showcases high solar reflectivity (>90 %) and infrared emissivity (∼0.85), leading to a cooling power of 36.4 W m−2. This implies pure solid salt cannot gain energy from solar illumination. To tackle this, the proposed system incorporated nano graphite and a hot mirror. Consequently, the absorbed solar energy increased from 67.6 W m−2 to 898.7 W m−2, resulting in a heating power of 794.0 W m−2 under AM 1.5G solar irradiance. With the proposed approaches, melting the salt with lowest solar concentration ratio of 15 (∼12.5 kW m−2) was achieved.falseBinary nitrate saltDirect absorption solar collectorHot mirrorNano graphiteSolar energy harvestingThermal emissivity[SDGs]SDG7journal article10.1016/j.cej.2024.1553172-s2.0-85203266454