Search results for "Thermal"

Diffusional kinetics of metalliding zinc into solid copper

1982

The process of incorporation of zinc into a copper cathode has been experimentally studied in a molten salt system at 381±2° C and at various current densities. The process is shown to be kinetically controlled by the diffusion of Zn into the solid matrix. A galvanostatic pulse titration technique has been used to determine the chemical diffusion coefficient at various alloy compositions, and an exponential relationship has been found between the diffusivity and the third power of the zinc concentration in the alloy. This relationship was then used in the diffusion equation within the solid matrix and a numerical integration was performed. Very good agreement was found between the calculate…

Diffusion, thermodiffusion, and thermal diffusion of polystyrene in solution

1962

Thermal effects during adsorption of n-butane on a slilicalite-1 membrane. A non-equilibrium molecular dynamics study

2007

Abstract Non-equilibrium molecular dynamic (NEMD) simulations have been used to study the kinetics of adsorption of n-butane molecules in a silicalite membrane. We have chosen this simple well-known process to demonstrate that the process is characterized by two stages, both non-isothermal. In the first stage the large chemical driving force leads to a rapid uptake of n-butane in all the membrane and a simultaneous increase in the membrane temperature, explained by the large enthalpy of adsorption, Δ H = − 61.6 kJ / mol butane. A diffusion coefficient for transport across the external surface layer is calculated from the relaxation time; a value of 3.4 × 10 −9 m 2 / s is found. During the a…

Thermal Diffusion and Partial Molar Enthalpy Variations of n-Butane in Silicalite-1

2008

International audience; We report for the first time the heat of transfer and the Soret coefficient for n-butane in silicalite-1. The heat of transfer was typically 10 kJ/mol. The Soret coefficient was typically 0.006 K−1 at 360 K. Both varied with the temperature and the concentration. The thermal conductivity of the crystal with butane adsorbed was 1.46 ±0.07 W/Km. Literature values of the isosteric enthalpy of adsorption, the concentration at saturation, and the diffusion coefficients were reproduced. Non-equilibrium molecular dynamics simulations were used to find these results, and a modified heat exchange algorithm, Soft-HEX, was developed for the purpose. Enthalpies of butane were al…

Colossal barocaloric effects in the complex hydride Li$_{2}$B$_{12}$H$_{12}$

2021

Traditional refrigeration technologies based on compression cycles of greenhouse gases pose serious threats to the environment and cannot be downscaled to electronic device dimensions. Solid-state cooling exploits the thermal response of caloric materials to external fields and represents a promising alternative to current refrigeration methods. However, most of the caloric materials known to date present relatively small adiabatic temperature changes ($|\Delta T| \sim 1$ K) and/or limiting irreversibility issues resulting from significant phase-transition hysteresis. Here, we predict the existence of colossal barocaloric effects (isothermal entropy changes of $|\Delta S| \sim 100$ JK$^{-1}…

Specific Heat and Transport Functions of Water

2020

Numerous water characteristics are essentially ascribed to its peculiarity to form stronghydrogen bonds that become progressively more stable on decreasing the temperature. However, thestructural and dynamical implications of the molecular rearrangement are still subject of debate andintense studies. In this work, we observe that the thermodynamic characteristics of liquid water arestrictly connected to its dynamic characteristics. In particular, we compare the thermal behaviourof the isobaric specific heat of water, measured in different confinement conditions at atmosphericpressure (and evaluated by means of theoretical studies) with its configurational contribution obtainedfrom the value…

ASSESMENT OF TEMPERATURE POLARIZATION IN MEMBRANE DISTILLATION CHANNELS BY LIQUID CRYSTAL THERMOGRAPHY

2014

AbstractThe measurement of local temperature distributions within a membrane distillation (MD) channel is a crucial step for the optimization of the channel and spacer geometry. This information allows the estimation of temperature polarization phenomena, which can dramatically influence the thermal efficiency of the process and the optimal choice of the geometric configuration (net spacer features, channel size, etc.). In the present work, a recently presented experimental technique, based on the use of thermochromic liquid crystals and digital image analysis, has been employed in order to assess the temperature polarization phenomena. The local heat transfer coefficient distribution on th…

Method for Identifying In-Flight Particles based on Digital Image Technologies in Thermal Spraying

2021

Abstract In thermal spray processes, the characteristics of in-flight particles (velocity and temperature) have a significant effect on coating performance. Although many imaging systems and algorithms have been developed for identifying and tracking in-flight particles, most are limited in terms of accuracy. One key to solving the tracking problem is to get an algorithm that can distinguish different particles in each image frame. As the study showed, when noise and interference are treated, particles are more readily identified in the background, leading to more accurate size and position measurements with respect to time. This approach is demonstrated and the results discussed.

Hydrothermal fluid venting in the offshore sector of Campi Flegrei caldera: A geochemical, geophysical, and volcanological study

2016

The ongoing unrest at the Campi Flegrei caldera (CFc) in southern Italy is prompting exploration of its poorly studied offshore sector. We report on a multidisciplinary investigation of the Secca delle Fumose (SdF), a submarine relief known since antiquity as the largest degassing structure of the offshore sector of CFc. We combined high-resolution morpho-bathymetric and seismo-stratigraphic data with onshore geological information to propose that the present-day SdF morphology and structure developed during the initial stages of the last CFc eruption at Monte Nuovo in AD 1538. We suggest that the SdF relief stands on the eastern uplifted border of a N-S-trending graben-like structure forme…

Geochemical investigations applied to active fault detection in a volcanic area: the North-East Rift on Mt. Etna (Sicily, Italy)

1999

Geochemical investigations were performed on the Northeast Rift of Mt. Etna, a prominent volcanic structure of this volcano. Low-temperature fumaroles were found on the upper part of this area and the isotopic compositions of C(CO2) and He suggest a likely magmatic origin of the emitted gases. On the contrary, very low degassing was found in the lower part of the NE-Rift, with CO2 concentrations generally very close to those in air. This pattern is probably due to sealing of the eruptive fissures by the repeated injections of magma solidified into dikes and by consequent shallow hydrothermal alteration of the fissured rocks due to residual magma degassing. High soil CO2 concentrations were …