Flow around and heat and mass transfer of a sphere with blowing at medium reynolds numbers

1976 ◽  
Vol 16 (4) ◽  
pp. 604-611 ◽  
Author(s):  
M. V. Bashkatov ◽  
S. I. Shabanov
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Reynolds Numbers

Effect of an Inert Gas on Heat and Mass Transfer in a Vertical Channel With Falling Films

1997 ◽  
Vol 119 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Wei Chen ◽  
G. C. Vliet
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Film Flow ◽  
Vertical Channel ◽  
Reynolds Numbers ◽  
Momentum Equation ◽  
Limited Data ◽  
Low Reynolds Numbers ◽  
Noncondensable Gases ◽  
Energy Equations

The effect of inert (noncondensable) gases on the heat and mass transfer (absorption) for channel flow of water vapor in conjunction with falling aqueous LiBr films is investigated. The hydrodynamic flow of the gas in the channel is approximated as fully developed. This is a “fair” assumption because of the low Reynolds numbers resulting from the low prevailing absorber pressures. The film flow is also assumed to be hydrodynamically developed. This greatly simplifies the problem, as the momentum equation need not be considered. Otherwise the continuity, species, and thermal energy equations govern the problem. Numerical results for a nominal case are presented for the velocity, temperature, and species distributions in the gas and liquid phase regions, and for the interface absorption rate. The effects of varying several parameters (including inerts concentration) on the above variables are also presented. Comparisons are also made with limited data in the literature.

scholarly journals Momentum, heat, and mass transfer analogy for vertical hydraulic transport of inert particles

2014 ◽  
Vol 68 (1) ◽  
pp. 15-25
Author(s):  
Darko Jacimovski ◽  
Radmila Garic-Grulovic ◽  
Zeljko Grbavcic ◽  
Mihal Djuris ◽  
Nevenka Boskovic-Vragolovic
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Single Phase ◽  
Reynolds Numbers ◽  
Particle Flow ◽  
Phase Flow ◽  
Vertical Flow ◽  
Hydraulic Transport ◽  
Single Phase Flow ◽  
Transfer Coefficients

Wall-to-bed momentum, heat and mass transfer in vertical liquid-solids flow, as well as in single phase flow, were studied. The aim of this investigation was to establish the analogy among those phenomena. Also, effect of particles concentration on momentum, heat and mass transfer was studied. The experiments in hydraulic transport were performed in a 25.4 mm I.D. cooper tube equipped with a steam jacket, using spherical glass particles of 1.94 mm in diameter and water as a transport fluid. The segment of the transport tube used for mass transfer measurements was inside coated with benzoic acid. In the hydraulic transport two characteristic flow regimes were observed: turbulent and parallel particle flow regime. The transition between two characteristic regimes (?*=0), occurs at a critical voidage ??0.85. The vertical two-phase flow was considered as the pseudofluid, and modified mixture-wall friction coefficient (fw) and modified mixture Reynolds number (Rem) were introduced for explanation of this system. Experimental data show that the wall-to-bed momentum, heat and mass transfer coefficients, in vertical flow of pseudofluid, for the turbulent regime are significantly higher than in parallel regime. Wall-to-bed, mass and heat transfer coefficients in hydraulic transport of particles were much higher then in single-phase flow for lower Reynolds numbers (Re<15000), while for high Reynolds numbers (Re>15000), there was not significant difference. The experimental data for wall-to-bed momentum, heat and mass transfer in vertical flow of pseudofluid in parallel particle flow regime, show existing analogy among these three phenomena.

Effect of Pin Tip Dual Clearance on Flow and Heat Transfer at Low Reynolds Numbers

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Michael L. Seibert ◽  
Neal E. Blackwell ◽  
Danesh K. Tafti
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat And Mass Transfer ◽  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
Microchannel Reactors ◽  
Pin Fins ◽  
The Heat Transfer Coefficient

This paper examines the augmentation of heat and mass transfer due to dual clearances on cylindrical pin fins, relative to a channel between parallel plates, in mini/microchannel reactors at low Reynolds numbers. In this work, diffusion limitations to heat and mass transfer in smooth-walled mini/microchannel reactors were minimized by the implementation of microcylinder pin fins with dual clearances that, (1) promote the production of instabilities in the wakes that enhance mixing and (2) reduce the viscosity dominated regions at pin-wall interfaces. A smooth catalyst coating is assumed on all exposed surfaces of the microchannel interior walls and pin fins. Due to the analogy of heat and mass transfer, augmentation of the Nusselt number is equivalent to the augmentation of the Sherwood number. Heat transfer augmentation is investigated in air (Pr = 0.705) at dual clearances ranging from 0 to 0.4 of the channel height and Reynolds numbers from 10 to 600. The pin fins and the clearance augmented the heat transfer coefficient by a factor of 4.0. The combination of the augmentation of the heat transfer coefficient and the increase in the surface area, by the clearances, results in an increase in the conductance over a plane channel, by a factor of 7.1. The results are extendable to overcoming laminar diffusion with laminar periodic wakes of fuel vapors such as methanol vapor in air where Scfuel ∼ Prair. For turbulent wakes impinging upon downstream pins, the results can be extended to fuel vapors with (Scfuel)turb ∼ (Prair)turb. A large eddy simulation (LES) approach was used in this study.

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