Biomass-derived photothermal conversion materials are considered to be promising evaporator choices for cost-effective, sustainable, and environmentally friendly solar vapor generation. Herein we ...demonstrate a double-layer flamed straw, which is a typical solar-driven interfacial evaporator that can directly convert solar energy into heat and then localize heat at interface for vapor generation. Benefiting from the unique structure of a natural corn straw, the flamed straw exhibits a high solar absorbance of 91%, ultralow thermal conductivity (0.042 W m–1 K–1), and a sufficient water supply. Notably, the flamed-straw evaporator achieves a fast evaporation rate of 1.497 kg m–2 h–1 and a high photothermal efficiency of 86% under 1 sun illumination, showing comparable efficiency with the reported studies. Our work highlights the promise of using the low-cost biomass-derived materials as highly effective solar vapor generators in the realm of seawater desalination and wastewater treatment.
Flexible thin films of poly(nickel‐ethylenetetrathiolate) prepared by an electrochemical method display promising n‐type thermoelectric properties with the highest ZT value up to 0.3 at room ...temperature. Coexistence of high electrical conductivity and high Seebeck coefficient in this coordination polymer is attributed to its degenerate narrow‐bandgap semiconductor behavior.
•Thermal behavior of solid-liquid phase change in graded copper foam was given.•The enhancement mechanism of the graded metal foam is clarified.•The effective thermal conductivity of composite PCM is ...analyzed.
The mechanisms responsible for the effect of metal foam, having a varying degree of porosity, on the phase change process in a phase change material (PCM) are not clearly understood. In this work, the pore-scale heat storage performance of the graded metal foams saturated with paraffin has been investigated using the computational fluid dynamics (CFD) method. The results demonstrate that the metal foam with a graded porosity accelerates the heat storage of PCM. In terms of the gradient dimension of the metal foam, the full melting time of the negative model 2 has been observed to be shortened by 2.6% as compared to the uniform model 1 and reduced by 15.5% as compared to the positive model 3. This is because the smaller the porosity of metal foam is, the faster the melting conducts. For the negative model, the relatively small porosity region is closer to the heat source than the large porosity region, which makes the heat transfer enhancement effect more evident than the weakening effect. Meanwhile, the full melting time shows an initial increasing trend, followed by a decrease for an increase in the porosity gradient difference. The optimal gradient difference is found to be −0.12 at the average porosity of 0.86 in this study.
Film is widely used in optoelectronic and semiconductor industries. The accurate measurement of the film thickness and refractive index, as well as the surface topography of the top and bottom ...surfaces are necessary to ensure its processing quality. Multiple measurement methods were developed; however, they are limited by the requirements of a known dispersion model and initial values of thickness and refractive index. Further, their systems are rarely compatible with surface topography measurement methods. We propose a constrained nonlinear fitting method to simultaneously measure the thickness and refractive index of film in a simple white-light spectral interferometer. The nonlinear phase extracted by the spectral phase-shifting is fitted with the theoretical nonlinear phase obtained by multiple reflection model. The constraints of nonlinear fitting are obtained by the interferometric signal of vertical scanning, reconstructed by the integration of the white-light spectral signal to avoid local minima. The proposed method does not require a priori knowledge of the dispersion model and initial values of thickness and refractive index, and its system is compatible with the vertical scanning interferometry (VSI) method to reconstruct the surface topography of the top and bottom surfaces of film. Three SiO
films with different thicknesses are measured, and the results show that the measured refractive index is within the theoretical value range of wavelength bandwidth and the measured thicknesses are closely aligned with the values provided by the commercial instrument. The measurement repeatability of refractive index reaches 10
. Measurements on a polymer film demonstrate that this method is feasible for measuring the film without a priori information.
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•Review of developments regarding the nanoscale thermophysical properties in China.•Present the experimental and simulation advances for thermal properties.•Highlight the main ...challenges and opportunities for future research.
Thermal transport properties are a significant criterion of performance evaluation for various fascinating nanoscale materials. In this review, we summarize the recent research progresses from China in the field of nanoscale thermal transport properties. Both experimental advances and atomic-level simulation development are reviewed for typical categories of nanoscale materials and structures, i.e., nanotubes and nanowires, nanofilms, nano-interfaces, nano-functional materials and those involving in near field radiation. Some fascinating aspects about the frontier issues in nanoscale heat transfer are also highlighted. In particular, researches have witnessed a remarkable growth in the interface-dominated microscopic thermal transport from both molecular dynamics simulation and experimental methods. In addition, challenges and opportunities will be touched on for the emerging field of near-field radiation. Which is dominated by simulation predictions but with encouraging experimental advances.
Electrical and thermal management in nanodevices by means of carbon nanotube is highly promising. One main challenge toward CNT-based nanoscale electrical and thermal management devices is the ...development of effective strategies for reducing the bundle–bundle interface resistance. Here we report a novel strategy, based on the densification of CNT bundles and the functionalization of inter-bundle interfaces for effectively enhanced interfacial electrical and thermal transport. The densification is realized by utilizing the local electrostatic cohesion; and the functionalization is realized by the interface-decorated functional groups. Experiments and theoretical analysis demonstrated obviously enhanced interfacial electrical and thermal conductance originates from: (1) local Coulomb electrostatic cohesion between CNT bundles due to surface-induced dipole moments. This effect can promote both electrical and thermal conductance nearly 2.8 times higher than non-functionalized counterpart. (2) Increased interfacial electron transport channels and thermal vibrations due to surface-decorated functional groups. This effect can bring about up to 75% and 95% improvement for thermal and electrical conductance, respectively. This study provides a new methodology for tunable operation of electrical and thermal properties at inter-bundle interfaces and guidance for design of CNT-based electrical and thermal management devices.
The optimization of pore structure for metal foam is considered a feasible approach for improving the overall heat transfer performance. Thus, we numerically investigated Kelvin cells with different ...throat areas and structures (elliptical Kelvin cell (EKC)) to characterize the influence on pressure drop and heat transfer coefficient using FLUENT 18.0. The standard k–ε model exhibited a better agreement with experimental data and required less time to achieve convergence. The results revealed that the throat area could not feasibly optimize the overall heat transfer performance. Moreover, the area goodness factor j/f that considered the influences of both heat transfer coefficient and pressure drop on the overall heat transfer performance of EKC with the higher than conventional Kelvin cell. Based on comparative analysis between pressure, velocity, turbulence kinetic energy, and temperature distribution, increasing the space and decreasing the angle between the skeleton and flow direction caused a significant pressure drop in the EKC samples. Owing to the existence of a lower temperature area at the leeward of skeletons and a small difference of impingement cooling on windward skeletons, the reduction of HTC was acceptable. Therefore, the EKC exhibited immense potential for enhancing the design of heat transfer devices.
•Kelvin cells with varying long and short throat diagonal and axes ratios.•Pressure drop and heat transfer coefficient were investigated comprehensively.•Pressure, velocity, and turbulence kinetic energy distributions were compared.•Increasing the elliptical axes ratio can optimize the overall heat transfer.
Interfacial thermal conductance (ITC) receives enormous consideration because of its significance in determining thermal performance of hybrid materials, such as polymer based nanocomposites. In this ...study, the ITC between sapphire and polystyrene (PS) was systematically investigated by time domain thermoreflectance (TDTR) method. Silane based self-assembled monolayers (SAMs) with varying end groups, -NH2, -Cl, -SH and -H, were introduced into sapphire/PS interface, and their effects on ITC were investigated. The ITC was found to be enhanced up by a factor of 7 through functionalizing the sapphire surface with SAM, which ends with a chloride group (-Cl). The results show that the enhancement of the thermal transport across the SAM-functionalized interface comes from both strong covalent bonding between sapphire and silane-based SAM, and the high compatibility between the SAM and PS. Among the SAMs studied in this work, we found that the ITC almost linearly depends on solubility parameters, which could be the dominant factor influencing on the ITC compared with wettability and adhesion. The SAMs serve as an intermediate layer that bridges the sapphire and PS. Such a feature can be applied to ceramic-polymer immiscible interfaces by functionalizing the ceramic surface with molecules that are miscible with the polymer materials. This research provides guidance on the design of critical-heat transfer materials such as composites and nanofluids for thermal management.
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•Baoshantao and Fenghuangshan deposits are typical skarn-type ore deposit.•Gold, Ag, Sb, Pb and Bi are mainly of lattice bound appearance in pyrite and chalcopyrite.•Skarn Cu (Au) ...mineralization was formed in a high-temperature, high oxidized magmatic-hydrothermal fluid.•A sedimentary component from subducted slab contributed to the skarn Cu (Au) mineralization.
In situ elemental compositions of sulfide minerals have been widely applied to trace ore-forming processes of magmatic-hydrothermal ore systems, yet the application of elemental compositions of the sulfide minerals in skarn ore deposits is still restricted by the lack of understanding of their behaviors during the skarn formation processes. In this study, in situ (LA-ICP-MS and EPMA) elemental compositions of medium- to coarse-grained euhedral pyrite and xenomorphic granular chalcopyrite are investigated for the Fenghuangshan and Baoshantao skarn Cu (Au) deposits in the Tongling region, eastern China. The results show that the studied pyrite samples have relatively consistent trace element composition characteristics, while the chalcopyrite studied displays high Zn, Ag and Pb contents, and relatively high Bi content. Au, Ag, Cu, Pb, Bi, Sb and Tl are mainly of lattice bound appearance in the pyrite structure. The Au, Ag, Sb, Pb and Bi are mainly incorporated into the chalcopyrite structure as coupled substitutions. Low Au (mainly < 0.1 ppm), Se (<3 ppm) and As (<100 ppm) contents, and high Co/Ni (mainly >1) and Se/Tl (mainly >10) ratios of the pyrite studied, and high Sn (>10 ppm) and low Tl (<1 ppm) contents of the chalcopyrite imply a high temperature, high oxygen fugacity and acidic pH magmatic-hydrothermal fluid for the Tongling skarn Cu (Au) mineralization. High Zn and Bi contents in the pyrite and chalcopyrite studied, and low Co/Ni ratios (<0.1) of the pyrite from quartz monzodiorite probably indicate a sedimentary component from subducted slab contribution to the magmatic-hydrothermal system.
Reconstruction methods for discrete data, such as the Moving Least Squares (MLS) and Moving Total Least Squares (MTLS), have made a great many achievements with the progress of modern industrial ...technology. Although the MLS and MTLS have good approximation accuracy, neither of these two approaches are robust model reconstruction methods and the outliers in the data cannot be processed effectively as the construction principle results in distorted local approximation. This paper proposes an improved method that is called the Moving Total Least Trimmed Squares (MTLTS) to achieve more accurate and robust estimations. By applying the Total Least Trimmed Squares (TLTS) method to the orthogonal construction way in the proposed MTLTS, the outliers as well as the random errors of all variables that exist in the measurement data can be effectively suppressed. The results of the numerical simulation and measurement experiment show that the proposed algorithm is superior to the MTLS and MLS method from the perspective of robustness and accuracy.
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