Abstract
To investigate the heat transfer phenomena for a package in a refrigerating room with downflow, the velocity profiles, temperature distributions and heat transfer coefficient were calculated numerically by fundamental equations derived under certain assumptions in the case where one wall of the vertical duct was isothermally heated and gas flowed downward through the duct in the laminar-flow range as a model of the package wall in the refrigerating room.
Downward forced convective flow is weakened by the free convective flow generated near the heated wall, and a stagnant How arises in the regular Rerange in this room. The cross-sectional temperature gradient near heated wall becomes steep with decreasing Re. The effect of free convection on average Nu is large in the range of low Re, becoming small with increasing Re.
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 and the average Nu agreed closely with the measured ones.
