Evaluation of Internal Thermal Flow and Heat Performance Augmentation Based on Novel Various Dimple With Insert Twisted Tape Configurations

ABSTRACT Numerical analysis of the fluid flow field is investigated based on various parameters of the dimple configuration in combination with an internal type insert. Experiments are conducted to observe the influence of dimple diameters with center twist tape on flow pattern, characteristics of friction factor, and heat performance. A twisted pipe with Reynolds numbers ( Re ) range of 1500 and 14,000 is used to check the effect of the dimple diameters with center twist tape on the thermal performance coefficient. Twisted tapes are inserted in various dimpled diameters to realize the numerical models. Results show that the quantitative investigation of pressure, heat, friction factor, and Nu in a twisted tape fitted dimpled tube is greater than that of a plain pipe. Qualitative investigation of flow fields is greater than that of a plain pipe. This is because the application of these devices increases secondary flow, swirl flow, and flow mixing, thereby raising the turbulence intensity and improving overall heat transfer. The pressure drop was changed between 10 and 65 kPa for different cases. The Nu was changed between 10 and 95 kPa for different cases. From the results, for 1 mm dimple dimmers, the minimum and maximum values of the thermal performance evaluation factor (PEF) are around 0.79 and 1.3.