This work experimentally studied the convective flow and heat transfer characteristics of a novel nanostructured heat transfer fluid: “ethanol/polyalphaolefin nanoemulsion” flowing through 12 circular minichannels of 1-mm diameter each. Ethanol/polyalphaolefin nanoemulsion is a thermodynamically stable system formed by dispersing ethanol into a mixture of “polyalphaolefin (PAO)” and surfactants. In this study, ethanol/PAO nanoemulsion is used as the working fluid to study the effect of ethanol nanodroplets on its convective flow and heat transfer characteristics. In addition, the effect of flow regime on its heat transfer is examined. It is found that using ethanol/PAO nanoemulsion fluids can improve convective heat transfer compared to that of pure PAO under both single- and two-phase flow regimes. For single-phase flow, there is no significant difference in Nusselt number between ethanol/PAO nanoemulsion and pure PAO in laminar flow regime. However, when entering transition flow regime, the ethanol/PAO nanoemulsion fluid showed a substantial increase in Nusselt number. Meanwhile, there is an increase in pressure drop and early onset of the laminar-turbulent transitional region for the ethanol/PAO nanoemulsion compared to pure PAO. The heat transfer coefficient of ethanol/PAO nanoemulsion can be further enhanced when the ethanol nanodroplets undergo phase change, which is hypothesized that such an effect is likely related to the enhanced interfacial thermal transport between the nanodroplets and base fluid under elevated temperature and the latent heat of phase changeable nanodroplets inside nanoemulsion. Further studies are needed to fully explore the convective heat transfer properties of nanoemulsion fluids.

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In current study, a hybrid mesoporous material infused with metallic oxide nanoparticles, MCM-48 with TiO2 nanoparticles, has been developed for potential application in water treatment. Using this unique hybrid structure, it can combine the advantages of the effective pollutants removal capability of metallic oxide nanoparticles, and the strong yet high permeable structure of mesoporous material. A modified hydrothermal method has been developed to synthesize three hybrid samples with TiO2 nanoparticles of three assorted sizes (15, 50 and 300nm), and their structure have also been characterized. The synthesized samples are tested for its capability of removing organic dye and trace metals using ICP-MS. The results have shown that while all three hybrid materials have shown over 80% adsorption rate for organic dye, the sample synthesized using 300nm TiO2 nanoparticle has shown the highest adsorption rate. Similarly, the highest adsorption rate for most trace metals test here also occurs in the sample made with 300nm TiO2 nanoparticle. Coincidentally, the sample prepared with 300nm TiO2 nanoparticle has a much larger internal surface area and smaller average pore size compared to the two other samples, which may lead to the higher adsorption rate of trace metals and organic dye tested here. This study has presented a hybrid mesoporous material that can be potentially used for pollutants removal of water treatment. Future studies are still needed to fully explore this hybrid material and its capability in water treatment.

In the current study, a hybrid mesoporous material infused with metallic oxide nanoparticles, MCM-48 with TiO 2 nanoparticles, has been developed for potential application in water treatment. MCM-48 belongs to a family of mesoporous siliceous materials-M41S, in which MCM-48 has a unique three-dimensional cubic symmetry structure. Using this hybrid approach, it will allow the polluted water to pass through the strong yet high permeable structure of mesoporous material and to allow enough time for the pollutants to react with the metallic oxide nanoparticles infused on the porous structure so that the polluted water can be treated without introducing secondary pollutants. A modified hydrothermal method has been developed to synthesize three samples of this hybrid material with TiO 2 nanoparticles of 15, 50, and 300 nm in diameter, respectively. The microstructures before and after the infusion of nanoparticles are characterized using scanning electron microscope and X-ray powder diffraction. Under the current study, the synthesized samples are tested for their capability of removing organic dye and trace metals. The results have shown that while all three hybrid materials have shown over 80% adsorption rate for organic dye, the sample synthesized using 300 nm TiO 2 nanoparticle has shown the highest adsorption rate. Similarly, the highest adsorption rate for most trace metals tested here also occurs in the sample made with 300 nm TiO 2 nanoparticle. Coincidently, the sample prepared with 300 nm TiO 2 nanoparticle has a much larger internal surface area and smaller average pore size compared to the two other samples, which may lead to the higher adsorption rate of trace metals and organic dye tested here. This study has presented a hybrid mesoporous material that can be potentially used for pollutants removal in water treatment. Future study is needed to investigate how to reuse this hybrid mesoporous material and to obtain a further understanding of the mechanism affecting the micro structures of the hybrid material.