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Author

Yimin Xuan

Bio: Yimin Xuan is an academic researcher from Nanjing University of Science and Technology. The author has contributed to research in topics: Materials science & Thermal energy storage. The author has an hindex of 2, co-authored 2 publications receiving 4483 citations.

Papers published on a yearly basis

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Journal ArticleDOI
TL;DR: In this article, an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat-transfer fluids, which are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluid, and they represent the best hope for enhancing heat transfer.
Abstract: Low thermal conductivity is a primary limitation in the development of energy-efficient heat transfer fluids that are required in many industrial applications. In this paper we propose that an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat transfer fluids. The resulting {open_quotes}nanofluids{close_quotes} are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluids, and they represent the best hope for enhancement of heat transfer. The results of a theoretical study of the thermal conductivity of nanofluids with copper nanophase materials are presented, the potential benefits of the fluids are estimated, and it is shown that one of the benefits of nanofluids will be dramatic reductions in heat exchanger pumping power.

4,634 citations

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TL;DR: Li et al. as discussed by the authors designed a facile way to fabricate eco-friendly porous SiC ceramics with robust structure and tunable porosity by impregnating flour paste into loofah followed by carbonization and molten silicon reaction processes.

38 citations

Journal ArticleDOI
TL;DR: In this article , a high performance solar thermal energy storage benefits from continuous thermal conductive channels and excellent solar absorptance of BSiC/PCMs composites is presented.

21 citations

Journal ArticleDOI
TL;DR: In this paper , an active and stable Bi/Nafion interface is fabricated over Bi nanosheets with the modification of Nafion, which exhibits superior CO 2 conversion with formate selectivity of above 95% in a wide potential range, partial current density of 72.12 mA cm −2 at − 1.07 V vs. RHE in H-type cell.
Abstract: Electrochemical CO 2 conversion into valuable products provides a promising solution for achieving a carbon-neutral energy cycle. Herein, an active and stable Bi/Nafion interface is fabricated over Bi nanosheets with the modification of Nafion, which exhibits superior CO 2 conversion with formate selectivity of above 95% in a wide potential range, partial current density of 72.12 mA cm −2 at − 1.07 V vs. RHE in H-type cell. The extraordinary CO 2 reduction performance could be ascribed to a high CO 2 permeability and enhanced local proton activity at the Bi/Nafion interface, which leads to promoted CO 2 adsorption and feasible proton-coupled electron transfer during the CO 2 reduction process. Computational investigations reveal the modification of Nafion offers a comfortable platform to enable the key intermediate *OCHO to be stable. This work offers a valuable insight into interfacial manipulation of electrodes to convert CO 2 to valuable products. • An efficient strategy of a stable, active Bi/Nafion interface was proposed and realized by Nafion modification. • The Bi/Nafion interface exhibits the high performance of electrochemical CO 2 reduction to formate. • The Bi/Nafion interface shows promoted CO 2 adsorption and enhanced local proton activity. • Nafion acts as a protective layer to ensure the stability of the electrode.

21 citations


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Journal ArticleDOI
TL;DR: In this article, the authors considered seven slip mechanisms that can produce a relative velocity between the nanoparticles and the base fluid and concluded that only Brownian diffusion and thermophoresis are important slip mechanisms in nanofluids.
Abstract: Nanofluids are engineered colloids made of a base fluid and nanoparticles (1-100 nm) Nanofluids have higher thermal conductivity' and single-phase heat transfer coefficients than their base fluids In particular the heat transfer coefficient increases appear to go beyond the mere thermal-conductivity effect, and cannot be predicted by traditional pure-fluid correlations such as Dittus-Boelter's In the nanofluid literature this behavior is generally attributed to thermal dispersion and intensified turbulence, brought about by nanoparticle motion To test the validity of this assumption, we have considered seven slip mechanisms that can produce a relative velocity between the nanoparticles and the base fluid These are inertia, Brownian diffusion, thermophoresis, diffusioplwresis, Magnus effect, fluid drainage, and gravity We concluded that, of these seven, only Brownian diffusion and thermophoresis are important slip mechanisms in nanofluids Based on this finding, we developed a two-component four-equation nonhomogeneous equilibrium model for mass, momentum, and heat transport in nanofluids A nondimensional analysis of the equations suggests that energy transfer by nanoparticle dispersion is negligible, and thus cannot explain the abnormal heat transfer coefficient increases Furthermore, a comparison of the nanoparticle and turbulent eddy time and length scales clearly indicates that the nanoparticles move homogeneously with the fluid in the presence of turbulent eddies so an effect on turbulence intensity is also doubtful Thus, we propose an alternative explanation for the abnormal heat transfer coefficient increases: the nanofluid properties may vary significantly within the boundary layer because of the effect of the temperature gradient and thermophoresis For a heated fluid, these effects can result in a significant decrease of viscosity within the boundary layer, thus leading to heat transfer enhancement A correlation structure that captures these effects is proposed

5,329 citations

Journal ArticleDOI
TL;DR: In this article, a model is developed to analyze heat transfer performance of nanofluids inside an enclosure taking into account the solid particle dispersion, where the transport equations are solved numerically using the finite-volume approach along with the alternating direct implicit procedure.

2,560 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a procedure for preparing a nanofluid which is a suspension consisting of nanophase powders and a base liquid, and their TEM photographs are given to illustrate the stability and evenness of suspension.

2,341 citations

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TL;DR: In this paper, the authors measured the effective thermal conductivity of mixtures of Al 2O3 and CuO, dispersed in water, vacuum pump, engine oil, and ethylene glycol.
Abstract: Effective thermal conductivity of mixtures of e uids and nanometer-size particles is measured by a steady-state parallel-plate method. The tested e uids contain two types of nanoparticles, Al 2O3 and CuO, dispersed in water, vacuum pump e uid, engine oil, and ethylene glycol. Experimental results show that the thermal conductivities of nanoparticle ‐e uid mixtures are higher than those of the base e uids. Using theoretical models of effective thermal conductivity of a mixture, we have demonstrated that the predicted thermal conductivities of nanoparticle ‐e uid mixtures are much lower than our measured data, indicating the dee ciency in the existing models when used for nanoparticle ‐e uid mixtures. Possible mechanisms contributing to enhancement of the thermal conductivity of the mixtures are discussed. A more comprehensive theory is needed to fully explain the behavior of nanoparticle ‐e uid mixtures. Nomenclature cp = specie c heat k = thermal conductivity L = thickness Pe = Peclet number P q = input power to heater 1 r = radius of particle S = cross-sectional area T = temperature U = velocity of particles relative to that of base e uids ® = ratio of thermal conductivity of particle to that of base liquid ¯ = .® i 1/=.® i 2/ ° = shear rate of e ow Ω = density A = volume fraction of particles in e uids Subscripts

2,156 citations

Journal ArticleDOI
TL;DR: In this paper, the authors explore four possible explanations for the anomalous thermal conductivity of nanofluids: Brownian motion of the particles, molecular-level layering of the liquid at the liquid/particle interface, the nature of heat transport in the nanoparticles, and the effects of nanoparticle clustering.

2,008 citations