Convective heat transfer in annular passages with high heat flux

An experimental study was performed on convective heat transfer with concentric annular gas flow and the inner tube heated. The Reynolds number ranged from 6000 to 10000 and the dimensionless heat flux parameter from 0.2 × 10-3 to 5.5 × 10-3. Special attention was paid to the examination of existing correlations for high heat flux transfer and also to the criteria for the occurrence of so-called laminarization of the annular flow. No laminarization was detected even for the highest heat flux case although they satisfied the proposed criteria for the occurrence of laminarization for circular tube flows. It is anticipated, therefore, that annular flow is less vulnerable to the laminarization than circular tube flow.