Heat transfer enhancement from tube bank in cross-flow with air can be achieved for energy saving by enhancing the flow turbulence nature. Adding splitter plates to the tubes’ trailing edges, besides, increasing the heat transfer surface’s roughness are proposed options to enhance the flow turbulence. However, few literatures are available to discuss this, moreover, almost all available CFD models employ RANS turbulence models and away from using large eddy simulation (LES). Accordingly, this work was presented to compare the employing of RANS and LES turbulence models for such problems at low Reynolds numbers. Toward this objective, a complete 3-D CFD model consisting of seven rows of tubes in flow direction is developed without using any symmetrical boundary conditions. The present study includes the impact of the Remax range (500-4500), for three surface relative roughnesses: ks/D of 0, 0.01, and 0.02. The local turbulence and heat transfer characteristics are discussed. The findings confirmed that the two proposed options for heat transfer enhancement succeeded in doubling it. The LES is superior to RANS models in resolving a wide spectrum scale of flow eddies. The results are useful in designing more efficient heat exchangers, especially at low Reynolds number. Key words: heat transfer, tube bank, RANS, LES, pressure drop |
