The enhanced photothermal characteristics of plasmonic ZrC/TiN composite nanofluids for direct absorption solar collectors

The selection of heat transfer medium is indispensable for the efficient realization of photothermal conversion. Nanofluids, thanks to their enhanced thermal properties and possible heat transfer applications, have been a topic of intense research. Also, nanofluid is an ideal working fluid for direct absorption solar collectors (DASCs). In this work, the stable ZrC/TiN nanofluids with high light absorption was prepared while a new irradiation mode was used to improve the photothermal conversion efficiency. Firstly, the composite optical characteristics of ZrC/TiN nanoparticles were numerically simulated by the finite-difference time-domain (FDTD) method. With the localized surface plasmon resonance (LSPR) effect by nano-TiN and the strong absorption exhibited by nano-ZrC, the 160 ppm ZrC/TiN nanofluids can achieve nearly 100% solar energy with a light distance of 1 cm. Secondly, the solar-to-thermal conversion efficiency of 160 ppm ZrC/TiN nanofluids was up to 73.7% though the side radiation, which was about 31% higher compared to the base fluids. In addition, this special flow model allows a lower temperature difference inside the ZrC/TiN nanofluids. Simulations and experiments showed that the ZrC/TiN nanofluids with the new irradiation mode has a relatively outstanding photothermal conversion capability, revealing the application prospects and potential of ZrC/TiN nanofluids in DASCs.