Thermal performance intensification of a circular heat exchanger tube integrated with compound circular ring-metal wire net inserts

Numerous studies have been recorded in developing the miniature heat transporting devices by the use of passive heat transfer enhancement technique. In the same context, a new novel insert geometry has been developed, which can enhance the convective heat transfer rate by the disruption of the thermal boundary layer. The circular ring with wire net inserts has been selected as the heat transfer enhancement insertion devices in the present research work. Three values of wire net grades (G = 4, 9, and 16) and the three values of pitch ratios (PR = 2, 3, and 4) are selected to investigate their effects on heat transfer (Nu), friction factor (f), and thermal enhancement factor (TEF), respectively. The air is used as the working fluid in the turbulent flow regime for which Reynolds number (Re) ranges from 5000 to 40,000. Significant enhancement over the smooth tube has been reported in terms of heat transfer and pressure drop. The maximum heat transfer enhancement of around 3.35 over the smooth tube is obtained for the PR = 2, and G = 16. The maximum TEF of 2.84 is retrieved for the PR = 3, and G = 9. The statistical correlations for Nu, and f also presented.