![]() ![]() Nanofluids can be prepared in two ways, a single step method (Zhu, 2004) or a two-step method (Eastman, 1997). In the past five years, nanofluids have also been explored for their electrical (Ganguly, 2009) and magnetic properties (Philip, 2009). From 1995 till 2008, nanofluids have been explored as a heat transfer fluid and the best results have been reported by Eastman and Choi (2001). Nanofluids are suspensions of nano-sized solid particles (1-100nm) in suitable base fluids. The term nanofluid was coined by Stephen Choi in 1995. Micro colloidal suspensions suffered from drawbacks like abrasion and sedimentation for which nanofluids were substituted by Robert Taylor (2009). Since thermal conductivity of pure liquids are much lesser in comparison to solids, suspension of solid particles in liquid could enhance the thermal conductivity and required optical properties. The concept of Direct absorption solar collectors in which working fluid acts as absorber and carrier of heat started replacing the conventional solar collectors (Otanicar, 2009). Conventional solar collectors transfer the heat from the flat plate to the working fluid but have the drawback of high heat loss. The development of nanotechnology contributed to nano suspensions, which can increase the efficiency of DASC. A major thrust in materials development is to identify new materials in order to increase the efficiency of Solar Thermal Collectors. Solar energy has been investigated for photovoltaic and thermal applications (Duffie, 1980). Increased consumption and growing demands of electrical appliances across the globe have posed a threat on the non- renewable energy resources and has made us exploit the maximum of renewable energy resources among which solar energy is the ultimate choice. Keywords: nanofluid, TiO 2, sedimentation, absorption, DASC UV results indicate the decrease in absorption from 440-500nm, complete absorption from 500-700nm and increase in absorption from 700-900nm.TiO 2 nanofluids are recommended as potential candidates for DASC in UV and IR regions. The SEM image reveals the agglomerated state of TiO 2 nanoparticles and the stability of TiO 2 nanofluid is reported as 9-10days. TiO 2 nanoparticles with a crystallite size of 43nm are obtained. Stability of nanofluid is essential for the applications of nanofluid in DASC. The prepared nanofluids are investigated for their stability by a gravity sedimentation method and for their optical property by UV-Vis spectroscopy. TiO 2-water nanofluids with weight fraction of 0.1% are prepared by a two-step process with sonication. Nanoparticles of Titanium dioxide (TiO 2) are prepared by sol gel and characterized by X Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). This present work investigates the absorption spectrum in TiO 2-water nanofluids to identify the potential application of nanofluids in Direct Absorption Solar Collectors (DASC). Nanofluids are tailored nano- colloidal suspensions of nanoparticles in a suitable base fluid. IVDepartment of Nanoscience and Technology, Alagappa University, Karaikudi, India IIIDepartment of Chemistry, Thiagarajar College of Engineering, Madurai, India IIDepartment of Physics, Thiagarajar College of Engineering, India IDepartment of Physics, Thiagarajar College of Engineering, Madurai, India Investigations on the absorption spectrum of TiO 2 nanofluidĪ L Subramaniyan I Sukumaran Lakshmi Priya II M Kottaisamy III R Ilangovan IV ![]()
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