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.