1,026,682 research outputs found
Effect of partial wetting on liquid/solid mass transfer in trickle bed reactors
The wetting efficiency of liquid trickle flow over a fixed bed reactor has been measured for a wide range of parameters including operating conditions, bed structure and physico-chemistry of liquid/solid phases. This data bank has been used to develop a new correlation for averaged
wetting efficiency based on five different non-dimensional numbers. Finally liquid/solid mass transfer has been determined in partial wetting conditions to analyse what are the respective effects of wetting and liquid/gas flow turbulence. These effects appear to be separated: wetting
being acting on liquid/solid interfacial area while the liquid/solid mass transfer coefficient is mainly connected to flow turbulence through the interstitial liquid velocity. A correlation has been proposed for liquid/solid mass transfer coefficient at very low liquid flow rate
Equilibrium States of Liquid, Solid, and Vapor and the Configurations for Copper, Tungsten, and Pores in Liquid-Phase Sintering
The equilibrium state of the liquid-solid structure during liquid-phase sintering (LPS) is pondered with respect to minimum energy geometries. Besides the solid-liquid ratio, several interfacial energies determine the most stable geometric configuration. In this study, we rely on the attributes of the copper or nickel as the liquid, tungsten as the solid, and vapor to solve for terminal configurations that include liquid pools inside the solid grains. Surface evolution is enabled using a stepwise computer program[1] to rearrange and reshape small grain clusters reflective of LPS based on a preset combination of wetting and dihedral angles. The findings show how different interfacial energies, as a result of oxidation or impurity segregation, play a role in determining the final geometry. The specific concern is identification of situations in which a liquid is stable inside the solid, as observed in some LPS materials.open112Nsciescopu
Why Are Alkali Halide Solid Surfaces Not Wetted By Their Own Melt?
Alkali halide (100) crystal surfaces are anomalous, being very poorly wetted
by their own melt at the triple point. We present extensive simulations for
NaCl, followed by calculations of the solid-vapor, solid-liquid, and
liquid-vapor free energies showing that solid NaCl(100) is a nonmelting
surface, and that its full behavior can quantitatively be accounted for within
a simple Born-Meyer-Huggins-Fumi-Tosi model potential. The incomplete wetting
is traced to the conspiracy of three factors: surface anharmonicities
stabilizing the solid surface; a large density jump causing bad liquid-solid
adhesion; incipient NaCl molecular correlations destabilizing the liquid
surface. The latter is pursued in detail, and it is shown that surface
short-range charge order acts to raise the surface tension because incipient
NaCl molecular formation anomalously reduces the surface entropy of liquid NaCl
much below that of solid NaCl(100).Comment: 4 pages, 3 figure
Free-energy landscape of nucleation with an intermediate metastable phase studied using capillarity approximation
Capillarity approximation is used to study the free-energy landscape of
nucleation when an intermediate metastable phase exists. The critical nucleus
that corresponds to the saddle point of the free-energy landscape as well as
the whole free-energy landscape can be studied using this capillarity
approximation, and various scenarios of nucleation and growth can be
elucidated. In this study we consider a model in which a stable solid phase
nucleates within a metastable vapor phase when an intermediate metastable
liquid phase exists. We predict that a composite critical nucleus that consists
of a solid core and a liquid wetting layer as well as pure liquid and pure
solid critical nuclei can exist depending not only on the supersaturation of
the liquid phase relative to that of the vapor phase but also on the wetting
behavior of the liquid surrounding the solid. The existence of liquid critical
nucleus indicates that the phase transformation from metastable vapor to stable
solid occurs via the intermediate metastable liquid phase, which is quite
similar to the scenario of nucleation observed in proteins and colloidal
systems. By studying the minimum-free-energy path on the free-energy landscape,
we can study the evolution of the composition of solid and liquid within nuclei
not limited to the critical nucleus.Comment: 9 pages, 8 figures, Journal of chemical physics to be publishe
Quantum Spin Liquid with Even Ising Gauge Field Structure on Kagome Lattice
Employing large-scale quantum Monte Carlo simulations, we study the extended
model on the kagome lattice. A quantum spin liquid phase
with effective even Ising gauge field structure emerges from the delicate
balance among three symmetry-breaking phases including stripe solid, staggered
solid and ferromagnet. This spin liquid is stabilized by an
extended interaction related to the Rokhsar-Kivelson potential in the quantum
dimer model limit. The phase transitions from the staggered solid to a spin
liquid or ferromagnet are found to be first order and so is the transition
between the stripe solid and ferromagnet. However, the transition between a
spin liquid and ferromagnet is found to be continuous and belongs to the 3D
universality class associated with the condensation of spinons. The
transition between a spin liquid and stripe solid appears to be continuous and
associated with the condensation of visons.Comment: 7 pages, 8 figure
Excitations of amorphous solid helium
We present neutron scattering measurements of the dynamic structure factor,
, of amorphous solid helium confined in 47 pore diameter
MCM-41 at pressure 48.6 bar. At low temperature, = 0.05 K, we observe
of the confined quantum amorphous solid plus the bulk
polycrystalline solid between the MCM-41 powder grains. No liquid-like
phonon-roton modes, other sharply defined modes at low energy ( 1.0
meV) or modes unique to a quantum amorphous solid that might suggest superflow
are observed. Rather the of confined amorphous and bulk
polycrystalline solid appear to be very similar. At higher temperature ( 1
K), the amorphous solid in the MCM-41 pores melts to a liquid which has a broad
peaked near 0 characteristic of normal liquid
He under pressure. Expressions for the of amorphous and
polycrystalline solid helium are presented and compared. In previous
measurements of liquid He confined in MCM-41 at lower pressure the
intensity in the liquid roton mode decreases with increasing pressure until the
roton vanishes at the solidification pressure (38 bars), consistent with no
roton in the solid observed here
Influence of Slip on the Plateau-Rayleigh Instability on a Fibre
The Plateau-Rayleigh instability of a liquid column underlies a variety of
fascinating phenomena that can be observed in everyday life. In contrast to the
case of a free liquid cylinder, describing the evolution of a liquid layer on a
solid fibre requires consideration of the solid-liquid interface. In this
article, we revisit the Plateau-Rayleigh Instability of a liquid coating a
fibre by varying the hydrodynamic boundary condition at the fibre-liquid
interface, from no-slip to slip. While the wavelength is not sensitive to the
solid-liquid interface, we find that the growth rate of the undulations
strongly depends on the hydrodynamic boundary condition. The experiments are in
excellent agreement with a new thin film theory incorporating slip, thus
providing an original, quantitative and robust tool to measure slip lengths
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