STUDY ON HEAT TRANSFER AUGMENTATION IN AN AIR HEATER USING RECTANGULAR WAVY FIN TURBULATORS

In the present study, the use of wavy fin turbulators on the annulus body of a double pipe air heater has been numerically investigated. The inner pipe consists of hot water whereas the annular section consists of cold air whose Reynolds Number (Re) ranged from 3000-15,000. Rectangular cross-sectioned wavy fin turbulators with various curvature ratios of 2, 3, 5, and 7.5 is numerically simulated to investigate the influence of curvature effects on turbulence. Results have been compared with the bare pipe and with rectangular straight fins. It is seen that wavy fin turbulators perform better (compared to (other two) bare and rectangular straight fin) than both of them by creating turbulence effects in the flow field. Nusselt number (Nu) is increased by 256% and 51% as compared to bare and rectangular straight fin type. Parametric studies revealed that as the curvature ratio (CR) is reduced, the turbulent intensity and turbulent kinetic energy increase with better heat transfer characteristics. The highest Thermo hydraulic performance index of 4.8 is noticed for the CR of 2 at a Re of 6000 and is 34% higher than the straight rectangular fin.