Photothermal Energy Conversion in Nanofluids

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AWARD ABSTRACT0932720PhelanThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The interaction of thermal radiation with nanofluids, which are nanoscale colloidal suspensions, has not been extensively examined. This research deals with fundamental thermal transport phenomena that occur when sufficiently intense thermal radiation is incident upon a nanofluid. Specifically, the irradiation will cause localized heating of the suspended nanoparticles, and, in turn, induce heating or boiling of the liquid. This proposal addresses the relevant phenomena through a series of experiments and analyses. Intellectual Merit. This research addresses questions such as the rate at which suspended nanoparticles selectively absorb thermal irradiation. A large component of the research is aimed at determining whether a vapor bubble nucleates from a heated nanoparticle in the same manner as compared to from a heated surface. Hence, determination of the incident radiative flux necessary to initiate boiling will be achieved. The temperatures obtained by the nanoparticles in response to the thermal irradiation, and the level of superheat required to initiate boiling at the surface of the nanoparticle will be determined. The optimum nanofluid particle size and particle loading distributions to maximize solar absorption while concurrently minimizing long-wavelength emission, will be sought. Broader Impacts. A promising application development of nanofluid-based, direct-absorption solar thermal collectors with efficiencies higher than conventional solar collectors. This may lead to cost effective and efficient solar energy collection systems. Furthermore, the initiation and control of novel chemical reactions may be brought about by irradiating unique nanofluids. High school students will be engaged in solar-energy-based science projects. Teaching modules will be developed for undergraduate students. An effort to involve and inform the general public regarding solar energy research and development will be made through publishing opinion and editorial articles in the popular media.