NUMERICAL ANALYSIS OF HEAT TRANSFER ENHANCEMENT IN CONICAL-NOZZLE TURBULATORS INSERTED TUBE

Year 2018, Volume: 13 Issue: 1, 7 - 17, 21.01.2018

Sibel Güneş , Toygun Dağdevir , Orhan Keklikcioğlu , Veysel Özceyhan

Abstract

     This
numerical work is associated with the investigation of the effect of turbulator
arrangement (diverging and converging) on heat transfer enhancement in conical
nozzle turbulators inserted circular tube. Three different pitch ratios
(PR=2.5, 5 and 7.5) were considered in the numerical analyses, using air as
test fluid. The numerical results of Nusselt number, friction factor and
thermal performance factor were introduced for the range of Reynolds numbers of
6000-24000. The obtained results showed that smaller pitch ratios provided more
heat transfer rate and pressure drop. As compared to converging nozzles,
diverging nozzles generated more effective turbulance/reverse flow, and thus
provided higher heat transfer and flow friction. Evidently, obtained results
revealed that the usage of nozzle-turbulators as a turbulence/reverse flow
generator has an important contribution on heat transfer improvement.

Keywords

Reverse Flow, Nozzle-Turbulator, Heat Transfer, Flow Friction, Nusselt Number

References

• 1. Eiamsa-ard, S., and Promvonge, P., (2010). Thermal Characterization of Turbulent Tube Flows over Diamond-shaped Elements in Tandem, International Journal of Thermal Sciences, Volume 49, Issue 6, pp:1051-1062.
• 2. Lu, B., and Jiang, P.X., (2006). Experimental and Numerical Investigation of Convection Heat Transfer in a Rectangular Channel with Angled Ribs, Experimental Thermal and Fluid Science, Volume:30, pp:513-521.
• 3. Yakut, K., Alemdaroglu, N., Sahin, B., and Celik, C., (2006). Optimum Design-Parameters of a Heat Exchanger Having Hexagonal Fins, Applied Energy, Volume:83, pp:82-98.
• 4. Sapali, S.N., and Patil, P.A., (2010). Heat Transfer During Condensation of HFC-134a and R-404A inside of a Horizontal Smooth and Micro-fin Tube, Experimental Thermal and Fluid Science, Volume:34, pp:1133–1141.
• 5. Dong, J., Chen, J., Zhang, W., and Hu, J., (2010). Experimental and Numerical Investigation of Thermal -hydraulic Performance in Wavy Fin-and-Flat Tube Heat Exchangers, Applied Thermal Engineering, Volume:30, pp:1377-1386.
• 6. Shaikh, N. and Siddiqui, M.H.K., (2007). Heat Transfer Augmentation in a Heat Exchanger Tube Using a Baffle, International Journal of Heat and Fluid Flow, Volume:28, pp:318-328.
• 7. Tandiroglu, A. and Ayhan, T., (2006). Energy Dissipation Analysis of Transient Heat Transfer for Turbulent Flow in a Circular Tube with Baffle Inserts, Applied Thermal Engineering, Volume:26, pp:178-185.
• 8. Promvonge, P., (2010). Heat Transfer and Pressure Drop in a Channel with Multiple 60° V-Baffles, International Communications in Heat and Mass Transfer, Volume:37, pp:835–840.
• 9. Ozceyhan, V., Gunes, S., Buyukalaca, O., and Altuntop, N., (2008). Heat Transfer Enhancement in a Tube Using Circular Cross Sectional Rings Separated From Wall, Applied Energy, Volume:85, pp:988-1001.
• 10. Akansu, S.O., (2006). Heat Transfers and Pressure Drops for Porous-ring Turbulators in a Circular Pipe, Applied Energy, Volume:83, Issue:3, pp:280-298.
• 11. Chang, S.W., Jan, Y.J., and Liou, J.S., (2007). Turbulent Heat Transfer and Pressure Drop in Tube Fitted With Serrated Twisted Tape. International Journal of Thermal Sciences, vol:46, 506-518.
• 12. Eiamsa-ard, S., Wongcharee, K., Eiamsa-ard, P., and Thianpong, C., (2010). Heat Transfer Enhancement in a Tube Using Delta-winglet Twisted Tape Inserts, Applied Thermal Engineering, Volume:30, pp:310–318.
• 13. Eiamsa-ard, S., Thianpong, C., and Eiamsa-ard, P., (2010). Turbulent Heat Transfer Enhancement by Counter/Co-swirling Flow in a Tube fitted with Twin Twisted Tapes, Experimental Thermal and Fluid Science, Volume:34, pp:53–62.
• 14. Gunes, S., Ozceyhan, V., and Buyukalaca, O., (2010). Heat Transfer Enhancement in a Tube with Equilateral Triangle Cross Sectioned Coiled Wire Inserts, Experimental Thermal and Fluid Science, Volume:34, pp:684-691.
• 15. Gunes, S., Ozceyhan, V., and Buyukalaca, O., (2010). The Experimental Investigation of Heat Transfer and Pressure Drop in a Tube with Coiled Wire Inserts Placed Separately from the Tube Wall, Applied Thermal Engineering, Volume:30, pp:1719-1725.
• 16. Promvonge, P., (2008). Thermal Performance in Circular Tube Fitted with Coiled Square Wires, Energy Conversion and Management, Volume:49, pp:980–987.
• 17. Promvonge, P., (2008). Heat Transfer Behaviors in Round Tube with Conical Ring Inserts, Energy Conversion and Management, Volume:49, pp:8–15.
• 18. Durmus, A., (2004). Heat Transfer and Exergy Loss in Cut Out Conical Turbulators, Energy Conversion and Management, Volume:45, pp:785–796.
• 19. Promvonge, P. and Eiamsa-ard, S., (2006). Heat Transfer Enhancement in a Tube with Combined Conical-nozzle inserts and Swirl Generator, Energy Conversion and Management, Volume:47, pp:2867–2882.
• 20. Eiamsa-ard, S., Promvonge, P., (2006). Experimental Investigation of Heat Transfer and Friction Characteristics in a Circular Tube Fitted with V-Nozzle Turbulators, International Communications in Heat and Mass Transfer, Volume:33, pp:591–600.
• 21. Ayhan, T., Azak, Y., Demirtas, C. and Ayhan, B., (1999). Numerical and Experimental Investigation of Enhancement of Turbulent Flow Heat Transfer in Tubes by Means of Truncated Hollow Cone Inserts, Heat Transfer Enhancement of Heat Exchangers, Kluwer Academic Publishers.
• 22. Yakut, K., Sahin, B., and Canbazoglu, S., (2004). Performance and Flow-induced Vibration Characteristics for Conical-ring Turbulators, Applied Energy, Volume.79, pp:65–76.
• 23. Yakut, K., and Sahin, B., (2004). Flow-induced Vibration Analysis of Conical Rings Used of Heat Transfer Enhancement in Heat Exchanger, Applied Energy, Volume:78, pp:273–288.
• 24. Promvonge, P. and Eiamsa-ard, S., (2007). Heat Transfer Behaviors in a Tube with Combined Conical-Ring and Twisted-Tape Insert, International Communications in Heat and Mass Transfer, Volume:34, pp:849-859.
• 25. Promvonge, P., and Eiamsa-ard, S., (2007). Heat Transfer and Turbulent Flow Friction in a Circular Tube Fitted with Conical-nozzle Turbulators, International Communications in Heat and Mass Transfer, Volume:34, pp:72-82.
• 26. Incropera, F.P., Witt, P.D., Bergman, T.L., and Lavine, A.S., (2006). Fundamental of Heat and Mass Transfer, John-Wiley & Sons.
• 27. Petukhov, B.S., (1970). Heat Transfer and Friction in Turbulent Pipe Flow with Variable Physical Properties, In Advances in Heat Transfer. Edited by: Hartnett JP, Irvine TS. New York: Academic Press.