Optimization simulation of heat transfer performance of internally finned tubes with blocked core-tube

Heat transfer and fluid flow performance in internally finned tube with blocked core-tube was numerically investigated with the realizable k-ε turbulence model and wall function method. The working fluid was air. The numerical method was validated by comparing the calculated results with available experimental data. It was found that there existed an optimal value for the ratio of core-tube outside diameter to outer-tube inside diameter, and this optimal value decreased with the increase of air flow rate. The optimal ratio was about 0.5-0.625 in the range of studied parameters. Meanwhile under the condition of identical pressure, the optimal ratio was also about 0.44-0.56. The conclusion is useful for the design of this kind of internally finned tubes.