Evaporation of nanofluid with induced bubbles under sun illumination

Abstract

Recently, various nanofluids have been explored to facilitate vapor production, showing the great efficacy of such fluids in solar evaporation. Plasmonic nanofluid generally requires high concentrations or mixing of individual nanofluids to achieve efficient evaporation. In contrast, carbon-based nanofluid, by its very nature, can achieve broad-spectrum absorption and require only very low concentrations. In this work, we introduce air bubbles within the carbon-based nanofluid to facilitate vapor evaporation. The dynamic bubbles effectively extend the incident light path and provide a large gas-liquid interface for moisture trapping, and the kinetic energy of the vapor generated during bubble bursting improves vapor diffusion. The coupling effect between the carbon-based nanofluid and the bubble resulted in a vapor production rate of 0.831 kg/(m2·h), with evaporation efficiencies three times that of pure water at a stable irradiance of approximately 750 W/m2, showing that both the nanofluid and bubbles play their positive roles in promoting evaporation. This work combines bubbling with evaporation systems, providing new insights into the use of solar evaporation