The Effect of Noncondensible Gases on Bubble Condensation in an Immiscible Liquid

A numerical study of the collapse of a bubble in a three-component, three-phase system is presented. The heat transfer is modeled using a quasi-steady integral boundary layer approach while the concentration profiles of noncondensibles are determined by solving the transient diffusion equation. It is shown that the experimentally determined collapse of small bubbles (between 1-mm and 3-mm initial radius) agrees with the model, while larger bubbles, which deform during their early history, are better described by a uniformly distributed noncondensible model.

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Structure-induced features of transport processes in an electroconsolidated FeNi composite

Modern Physics Letters B ◽

10.1142/s021798492150425x ◽

2021 ◽

pp. 2150425

Author(s):

G. Ya. Khadzhai ◽

S. R. Vovk ◽

R. V. Vovk ◽

E. S. Gevorkyan ◽

M. V. Kislitsa ◽

...

Keyword(s):

Heat Transfer ◽

Interdiffusion Coefficient ◽

Transport Processes ◽

Phase System ◽

Similar Composition ◽

Enhanced Diffusion ◽

Plasma Sintering ◽

Three Phase ◽

Spark Plasma ◽

Feni Alloy

The structure and processes of mass, charge and heat transfer are investigated in an equiatomic Fe–Ni composite fabricated by electroconsolidation using the spark plasma sintering (SPS) technology. The system contains regions of almost pure Fe and Ni, separated by areas with variable concentration of components, formed in consequence of the interdiffusion in the electroconsolidation process. The interdiffusion coefficient of the Fe–Ni system has been revealed to be significantly higher than that of an alloy of a similar composition at the same temperature, which is likely the result of the employed SPS technology and the enhanced diffusion along the grain boundaries. The concentration dependence of the interdiffusion coefficient passes through a maximum at a Ni concentration of [Formula: see text] at.%. The electrical and thermal conductivity of the studied system is significantly higher than that of an alloy of the same composition. The temperature dependence of the resistivity of the sample in the range 5–300 K is due to the scattering of electrons by defects and phonons, and the scattering of electrons by phonons fits well to the Bloch–Grüneisen–Wilson relation. The boundaries of the conductivity of the investigated composite correspond to the Hashin–Shtrikman boundaries for a three-phase system, if Fe, Ni and the FeNi alloy are selected as phases.

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Heat Transfer With Vaporization of a Liquid by Direct Contact in Another Immiscible Liquid: Experimental and Numerical Study

Journal of Heat Transfer ◽

10.1115/1.2910621 ◽

1991 ◽

Vol 113 (3) ◽

pp. 705-713 ◽

Cited By ~ 6

Author(s):

L. Tadrist ◽

J. Sun ◽

R. Santini ◽

J. Pantaloni

Keyword(s):

Heat Transfer ◽

Theoretical Model ◽

Void Fraction ◽

Direct Contact ◽

Numerical Study ◽

Water System ◽

Immiscible Liquid ◽

Transfer Model ◽

Two Phase ◽

Spray Column

An experimental setup was designed to study direct-contact evaporators using a liquid dispersed in another immiscible liquid. The study was carried out on an n-pentane–water system to determine the influence of different parameters on these systems, and consequently to construct a model for this type of evaporator. An optical probe was used to measure the local void fraction. At different column abscissas along a selected diameter, the local void fraction variations were determined. The shape of the curves can be attributed to the different processes occurring in the spray column. A one-dimensional heat transfer model in the spray column was established. Simplifying assumptions were used to establish and resolve the set of equations governing heat transfer and two-phase flow. The vaporization process induces a volumetric expansion of the two-phase mixture. A theoretical model was used, in which the coalescence between the spherical fluid particles is taken into account. Different coalescence laws dependent on particle density were introduced into the theoretical model and then tested. The numerical results are discussed and compared with the experimental data obtained for the n-pentane–water system.

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Numerical Study of the Thermal Behavior of a Composite Phase Change Material (PCM) Room

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.1824 ◽

2018 ◽

Vol 8 (2) ◽

pp. 2663-2667 ◽

Cited By ~ 2

Author(s):

N. Ben Khedher

Keyword(s):

Heat Transfer ◽

Phase Change ◽

Thermal Performance ◽

Phase Change Materials ◽

Numerical Study ◽

Indoor Temperature ◽

Three Phase ◽

Chloride Hexahydrate ◽

Hot Weather ◽

Building Walls

In this study, thermal performance of building walls integrated with phase change materials (PCM) was evaluated in terms of indoor temperature reduction and heat transfer time delay. PCM was incorporated as thin layer placed longitudinally within walls. The thermal performance of a room with and without PCM was evaluated numerically. The developed model is based on the enthalpy formulation for PCM melting and solidification, which is solved by an implicit finite difference method. The effect of PCM type on heat gain indoors was studied. Three phase change materials (n-octadecane, n-eicosane and calcium chloride hexahydrate) were tested in hot weather. Results showed that octadecane is the best in ensuring an indoor temperature close to 27 °C for the test room. Moreover, optimal thickness of the PCM layer within the walls is critical for heat transfer reduction and management and should be carefully chosen.

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