scholarly journals Momentum and Heat Transfer in Two-Phase Bubble Flow in Concentric Annuli

1982 ◽  
Vol 25 (209) ◽  
pp. 1746-1754 ◽  
Author(s):  
Shinichi SARUWATARI ◽  
Yoshifusa SATO ◽  
Michio SADATOMI
1967 ◽  
Vol 89 (2) ◽  
pp. 185-193 ◽  
Author(s):  
M. E. Goldstein ◽  
Wen-Jei Yang ◽  
J. A. Clark

An analysis has been made to determine the heat transfer and friction characteristics in a two-phase (gas-liquid) flow over a circular cylinder. It is demonstrated that the resulting two-layer flow problem can be formulated exactly within the framework of laminar boundary layer theory. Two cases are studied; (1) For the parameter E greater or equal to 0.1 and the drop trajectories straight and, (2) For E less or equal to 0.1 and for any drop trajectory. Solutions obtained in power series include the local liquid-film thickness, velocity and temperature profiles, skin friction and Nusselt number. Numerical results disclose a significant increase in both heat transfer rate and skin friction over those of a pure gas flow. The theoretical prediction compares favorably with experimental results of Acrivos, et al. [1].


2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Raj M. Manglik ◽  
Milind A. Jog

The scientific understanding of multiphase interfaces and the associated convective mass, momentum, and heat transport across and along their boundaries, provide the fundamental underpinnings of the advancement of boiling heat transfer, two-phase flows, heat pipes, spray cooling, and droplet-film coating, among many other engineering applications. Numerous studies have tried to characterize the interfacial behavior and model their mechanistic influences either directly or implicitly via parametric experimental investigations and/or simulations. The goal of advancing our understanding as well as developing generalized, perhaps “universal,” and more accurate phenomenological or mechanistic correlations, for predicting mass, momentum, and heat transfer, continues to engage the worldwide research community. A collection of some such current investigations that are representative of both basic and applied issues in the field is presented in this special issue of the Journal of Heat Transfer.


2020 ◽  
Vol 2020 (0) ◽  
pp. OS12-06
Author(s):  
Kyoya ARAKI ◽  
Hideki MURAKAWA ◽  
Katsumi SUGIMOTO ◽  
Hitoshi ASANO ◽  
Daisuke ITO ◽  
...  

1977 ◽  
Vol 99 (4) ◽  
pp. 574-579 ◽  
Author(s):  
M. S. Bhatti

A theory is developed for two-phase flow wherein droplets suspended in a gas stream penetrate the hydrodynamic boundary layer in the laminar entry region of a straight channel with isothermal walls. A fraction of the droplets is captured by the boundary layer due to isotropic turbulence superimposed at the edge of the the boundary layer. Transverse motion of the droplet is under the influence of Stokes’ drag, buoyancy, gravity and inertia forces. Axial motion of the droplets is with the local gas velocity without slip. Droplet trajectories are determined by the numerical integration of the equations of motion employing the fourth order Runge-Kutta technique. Using these results, a two region model is developed for determining the convective heat transfer conductance augmented by droplet vaporization. Momentum and heat transfer results are presented for air/water-droplet system containing 10μ–50μ droplets under typical conditions encountered in dry cooling towers.


Author(s):  
V.N. Moraru

The results of our work and a number of foreign studies indicate that the sharp increase in the heat transfer parameters (specific heat flux q and heat transfer coefficient _) at the boiling of nanofluids as compared to the base liquid (water) is due not only and not so much to the increase of the thermal conductivity of the nanofluids, but an intensification of the boiling process caused by a change in the state of the heating surface, its topological and chemical properties (porosity, roughness, wettability). The latter leads to a change in the internal characteristics of the boiling process and the average temperature of the superheated liquid layer. This circumstance makes it possible, on the basis of physical models of the liquids boiling and taking into account the parameters of the surface state (temperature, pressure) and properties of the coolant (the density and heat capacity of the liquid, the specific heat of vaporization and the heat capacity of the vapor), and also the internal characteristics of the boiling of liquids, to calculate the value of specific heat flux q. In this paper, the difference in the mechanisms of heat transfer during the boiling of single-phase (water) and two-phase nanofluids has been studied and a quantitative estimate of the q values for the boiling of the nanofluid is carried out based on the internal characteristics of the boiling process. The satisfactory agreement of the calculated values with the experimental data is a confirmation that the key factor in the growth of the heat transfer intensity at the boiling of nanofluids is indeed a change in the nature and microrelief of the heating surface. Bibl. 20, Fig. 9, Tab. 2.


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