Negative thermophoresis of nanoparticles in the free molecular regime

Wang, Jun; Li, Zhi Gang

doi:10.1103/physreve.86.011201

Cited by 20 publications

(6 citation statements)

References 37 publications

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“…3 Results and discussion In this study, an armchair CNT with chirality (17,17) and length of 75 nm is considered for all cases. Thermal gradients of 0.2, 0.5, 0.7 and 0.85 K/nm are imposed along the axis of the CNT wherein water nanodroplets of different sizes are confined.…”

Section: Methodsmentioning

confidence: 99%

“…More recently, and motivated for potential applications of nanofluid solutions, this phenomenon has also been studied in dispersions of nanoscale particles immersed in fluids [14][15][16] . Thermophoresis is fundamentally related with the phenomenon of thermodiffusion in liquid solutions 4,17 , also called the Ludwig-Soret effect 4,12 after Carl Ludwig 18 and Charles Soret 19 who independently studied this phenomenon in the 19th century. Nowadays, the advent of extremely accurate nanofabrication techniques has led to envision novel integrated nanofluidic devices wherein the functional stations are connected by nanoconduits [20][21][22] .…”

Section: Introductionmentioning

confidence: 99%

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Water thermophoresis in carbon nanotubes: the interplay between thermophoretic and friction forces

Oyarzua

Walther

Zambrano

2018

Phys. Chem. Chem. Phys.

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Thermophoresis is the phenomenon wherein particles experience a net drift induced by a thermal gradient. In this work, molecular dynamics simulations are conducted to study with atomistic detail the thermophoresis of water nanodroplets inside carbon nanotubes (CNTs) and its interplay with the retarding liquid-solid friction. Different applied temperatures, thermal gradients, and droplet sizes are used to reveal the dynamics of the two kinetic regimes of the thermophoretic motion in CNTs. The results indicate that during the droplet motion, the thermophoretic force is independent of the velocity of the droplet, whereas the magnitude of the retarding friction force exhibits a linear dependence. In fact, in the initial regime the magnitude of the friction force increases linearly with the droplet velocity, until the thermophoretic force is balanced by the friction force as the droplet reaches its terminal velocity in the final regime. In addition, an increase in the magnitude of the thermophoretic force is found for longer water droplets. These findings provide a deeper understanding of liquid transport driven by temperature gradients in nanoconfined geometries where liquid-solid interfaces govern fluidics.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Water thermophoresis in carbon nanotubes: the interplay between thermophoretic and friction forces

Oyarzua

Walther

Zambrano

2018

Phys. Chem. Chem. Phys.

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“…However, when the temperature of the gas with particles is cooler than that of the surfaces, the direction of force is changed to the opposite direction. This force is called negative thermophoresis. , Essentially, thermophoresis and negative thermophoresis are a pair of forces with opposite directions, whose boundary corresponds to whether the cold surface temperature is higher than the gas temperature, that is, when the surface temperature is cooler than that of gas, the force on particles is thermophoresis; otherwise, the force is negative thermophoresis.…”

Section: Overview Of Mechanismsmentioning

confidence: 99%

Collection of Particles on Cold Surfaces: A Review

Zhang

Gan

2020

Ind. Eng. Chem. Res.

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Particles in gas always have a tendency to move upward and be collected on cold surfaces. This behavior, which has resulted from the interaction of several mechanisms, including Brownian diffusion, inertial impaction, interception, thermophoresis, and diffusiophoresis, is complex. These mechanisms have been previously investigated profoundly. However, a systematic summary is scarce, and inconsistent statements and misunderstandings about these mechanisms have been observed in previous works. To understand the behavior of particle collection on cold surfaces well, the status of these mechanisms has been reviewed, and a mechanism coordinator chart has been established in this paper. Meanwhile, the discrimination of diffusiophoresis in different fields has been analyzed. The research status of the behavior of particle collection on cold surfaces in three types of scenarios has been introduced. Finally, future research directions concerning this topic have been suggested.

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“…, . The explicit expressions of the parameters entering equation (8) can be found in the supplementary material as equations (A3) and (A4). In effect, depending on the values of the three parameters ℘ B T , , the system can be entangled or disentangled.…”

Section: Four Spins Case: Analytical Treatmentmentioning

confidence: 99%

“…">IntroductionWith the advances in nanotechnology enabling controlled miniaturization and functionalization of nanostructured materials, questions related to the thermodynamical properties are gaining increased attention. Several theoretical proposals were put forward for nanoscale Brownian motors [1], refrigerators [2] and quantum heat engines [3][4][5][6][7][8][9][10][11][12][13]. On the other hand, for finite systems, the application of the laws of thermodynamics is the subject of an ongoing debate [14].…”

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confidence: 99%

Quantum Otto heat engine based on a multiferroic chain working substance

et al. 2014

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We study a quantum Otto engine operating on the basis of a helical spin-1/2 multiferroic chain with strongly coupled magnetic and ferroelectric order parameters. The presence of a finite spin chirality in the working substance enables steering of the cycle by an external electric field that couples to the electric polarization. We observe a direct connection between the chirality, the entanglement and the efficiency of the engine. An electric-field dependent threshold temperature is identified, above which the pair correlations in the system, as quantified by the thermal entanglement, diminish. In contrast to the pair correlations, the collective many-body thermal entanglement is less sensitive to the electric field, and in the high temperature limit converges to a constant value. We also discuss the correlations between the threshold temperature of the pair entanglement, the spin chirality and the minimum of the fidelities in relation to the electric and magnetic fields. The efficiency of the quantum Otto cycle shows a saturation plateau with increasing electric field amplitude.Keywords: quantum heat engine, quantum entanglement, frustrated spin chain, multiferroic system IntroductionWith the advances in nanotechnology enabling controlled miniaturization and functionalization of nanostructured materials, questions related to the thermodynamical properties are gaining increased attention. Several theoretical proposals were put forward for nanoscale Brownian motors [1], refrigerators [2] and quantum heat engines [3][4][5][6][7][8][9][10][11][12][13]. On the other hand, for finite systems, the application of the laws of thermodynamics is the subject of an ongoing debate [14]. One of the fundamental questions concerns the size limit to which the working substance might be scaled down. Recent studies point out that the quantum nature of a size-quantized working substance, e.g. a quantum heat engine, may lead to a close connection between the efficiency of the cycle and quantum correlations [15], which can be quantified in terms of the entanglement [16][17][18], behavior that is atypical for classical engines. According to the fundamental laws of thermodynamics, the efficiency of a classical engine is independent of its detail and is solely determined by the character of the cycle itself and the temperatures of the heat baths. The quantum nature of the working substance, however, has key consequences for the engine output power as well. Recently it was shown that purely quantum phenomena, such as noise-induced coherence, yield greater engine output power [19,20].In general, physical phenomena at the cross-over of quantum mechanics and thermodynamics are the subjects of the emergent field of quantum thermodynamics where, among other topics, questions are addressed as to what extent standard classical thermodynamic cycles, such as Carnot or Otto cycles, can be reformulated for quantum systems [4]. A key issue thereby is the difference between thermodynamic and quantum adiabatic processes. For example, a thermodynamical ...

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Negative thermophoresis of nanoparticles in the free molecular regime

Cited by 20 publications

References 37 publications

Water thermophoresis in carbon nanotubes: the interplay between thermophoretic and friction forces

Water thermophoresis in carbon nanotubes: the interplay between thermophoretic and friction forces

Collection of Particles on Cold Surfaces: A Review

Quantum Otto heat engine based on a multiferroic chain working substance

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