CONVECTIVE INSTABILITY OF HEAT AND MASS-TRANSFER FOR LAMINAR FORCED-CONVECTION IN THE THERMAL ENTRANCE REGION OF HORIZONTAL RECTANGULAR CHANNELS

NCUIR > Engineering College > Graduate Institute of Mechanical Engineering > journal & Dissertation > Item 987654321/27136

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/27136

Title:	CONVECTIVE INSTABILITY OF HEAT AND MASS-TRANSFER FOR LAMINAR FORCED-CONVECTION IN THE THERMAL ENTRANCE REGION OF HORIZONTAL RECTANGULAR CHANNELS
Authors:	LIN,JN;TZENG,PY;CHOU,FC;YAN,WM
Contributors:	機械工程研究所
Keywords:	VERTICAL PARALLEL PLATES;NATURAL-CONVECTION;MIXED CONVECTION;GRAETZ PROBLEM;EVAPORATION;FLOWS
Date:	1992
Issue Date:	2010-06-29 18:08:40 (UTC+8)
Publisher:	中央大學
Abstract:	A numerical analysis is performed to investigate the onset of convective instability and latent heat transfer, in connection with the vaporization of a liquid-water film, for laminar forced convection in the thermal entrance region of horizontal rectangular ducts. Major dimensionless groups identified are aspect ratio gamma, effective Rayleigh number Ra+, Prandtl number Pr, and Schmidt number Sc. The effects of the changes of bottom wall temperature T(w), relative humidity of air phi, gamma, and Ra+ on the local Nusselt number Nu(z). Sherwood number Sh(z), and the onset point of convective instability are examined in detail. To understand the effects of the selection of different criteria on the onset point, two typical definitions are chosen: a 2 percent departure of Nu(z) from that of Graetz theory and the local minimum Nu(z). Results show that the onset point, under the effects of the combined buoyancy forces of thermal and mass diffusion, is rather advanced compared with that under the effect of thermal buoyancy force only. Results also show that the convective instability is affected by changes of phi and T(w) for fixed gamma. Additionally, the influence of water evaporation along the wetted wall on the laminar mixed convection heat transfer in this study is also presented.
Relation:	INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
Appears in Collections:	[Graduate Institute of Mechanical Engineering] journal & Dissertation

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