2-LAYER-MODEL PREDICTIONS OF HEAT-TRANSFER INSIDE ENHANCED TUBES

Turbulent flow in axisymmetric enhanced tubes with repeated transverse rectangular disruptions was simulated using the two-layer turbulence model of Chen and Patel [1]. The predictions were in good agreement wi th experimental data for friction factors and both local and average N usselt numbers. The low-Reynolds-number two-equation model of Lam and Bremhorst [2] was considered, and the predicted results were also comp ared with local heat transfer measurements. This model overestimated t he local Nusselt numbers at some locations by about a factor of 2. Res ults from the two turbulence models were also compared for a sudden pi pe-expansion geometry. The Lam and Bremhorst model yielded acceptable local Nusselt number predictions, while the Chen and Patel model under predicted the local Nusselt numbers and predicted the location of the heat transfer maximum further upstream.