Numerical Analysis of Free Convective Heat Transfer in Vertical Duct with Laminar Upflow

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN

Noboru Sakai¹  Tamotsu Hanzawa¹  Yu-Tien Hsiao¹ 

[1] Department of Food Engineering, Tokyo University of Fisheries

关键词: Heat Transfer;    Heat Transfer Coefficient;    Free-Forced Convection;    Combined Laminar Flow;    Combined Flow Pattern;   

DOI  :  10.1252/jcej.26.493

来源: Maruzen Company Ltd

【 摘 要 】

References(19)To elucidate the heat transfer phenomena for a package in a refrigerating room with upflow, we considered a vertical-duct model in which one wall was isothermally heated and gas flowed upward through the duct in the laminar-flow range. The velocity profiles, temperature distributions and the local and average heat transfer coefficient were calculated numerically by fundamental equations.The main fluid flow is drawn toward the heated wall in the range of low Re and becomes parallel to the axial coordinate with increasing Re. The higher on the heated wall, the smaller is the local Nusselt number. However, the average Nusselt number does not undergo much change with increasing Re and Gr. A correlated equation for heat transfer was obtained under the operating conditions of this calculation.To check these calculated results, the temperature distributions and heat transfer coefficient were measured experimentally under the same operating conditions as those of the theoretical analysis. The calculated temperature distributions agreed closely with the measured ones.To compare the heat transfer coefficient of the downflow and the upflow, we found that the latter is about twice that of the former.

【 授权许可】

Unknown