Numerical simulation of dimled tubes for heat transfer enhancement

Heat transfer enhancement was investigated in a coaxial-pipe heat exchanger using dimples on the inner tube. Through three-dimensional numerical simulation, the incompressible fluid flow and heat transfer characteristics in the dimpled tube were studied. This computational model is built up by RNG κ-ε turbulent govern equation and SIMPLE algorithm. By this study, the thesis shows that the geometry structures such as the size, depth and the distributed density of dimples affect heat exchange performance of dimpled tubes. When Reynolds number is low, the heat exchange efficiency of tubes with smaller dimple is higher. When Reynolds number is high, the heat exchange efficiency of tubes with bigger dimple is higher.