단열관을 위한 원통 환상공간 내에서의 복합 열전달

Conjugate Heat Transfer in Cylindrical Annulus for an Insulated Tube

The effect of the gap width on conjugate heat transfer in the cylindrical annulus for an insulated tube has been studied numerically by the finite difference method. The parameters considered here are the Rayleigh number, Ra, the dimensionless insulated wall thickness, $W/D_i$ and the dimensionless gap width, S/W. As S/W increases, the mean wall temperature increases at the inside wall of annulus and decreases at the outside walls of annulus and the insulated tube at $S/W{\leq}0.5$, and then slightly increases at $Re=10^4$, $W/D_i=1.47$. The heat transfer rate decreases at $S/W{\leq}0.5$ and then increases apparently as S/W increases at $Re=10^4$, W/Df=1.47. Therefore, it is considered that $$S/W{\sim_=}0.5$$ is the optimum gap width for the effect of insulation at $Re=10^4$, $W/D_f=1.47$.