Photothermal energy conversion in liquid nanoparticle suspensions

Liquid nanoparticle suspensions, popularly termed "nanofluids," have been the subject of numerous investigations because of their interesting thermal transport properties. Their propensity to scatter and absorb electromagnetic radiation enables other applications that can take advantage of both their radiative and thermal transport properties. In particular, we are working to develop direct-absorption solar thermal collectors in which nanofluids serve to absorb incident sunlight, thus heating the fluid directly and more efficiently than conventional solar collectors. Our experimental results, in which we irradiate nanofluids with a continuous-wave laser, demonstrate that boiling can be induced at lower incident light fluxes compared to a thin layer of pure water in front of a black absorptive backing. These findings suggest that improved solar energy conversion systems can be developed, including solar-driven direct-steam generators.