NUMERICAL AND EXPERIMENTAL INVESTIGATIONS ON PERFORMANCE EVALUATION OF A CONICAL OFFSET VORTEX GENERATOR INSERTS TO IMPROVE CONVECTIVE HEAT TRANSFER COEFFICIENT

Year 2020, , 858 - 872, 01.10.2020

Shivaji Mundhe Rupa Bindu

https://doi.org/10.18186/thermal.800276

Cited By: 1

Abstract

The passive augmentation technique is widely used by researchers from thermal engineering field and it has shown excellent results for convective heat transfer rate. This paper shows the numerical and experimental findings for convective heat transfer characteristics and friction coefficient. Tests were conducted for turbulent flow, using air as medium through a uniformly heated steel pipe containing a novel kind of insert named as Conical offset Vortex Generator (COVG). The simulation tests were performed for turbulent flow with varying Reynolds number in the range 4000 to 50000. The parameters were analyzed during tests are pitch to smooth tube diameter ratio (p/d) and angle of attack (α). Various simulation tests were carried out with the help of ANSYS Fluent software to optimize the geometry. The simulation tests were carried out for different angle of attack (α = 15°, 30°, 60°). COVG with angle of attack (α = 60°) shows more enhancement in heat transfer rate, hence it was used for the experimentation purpose. The experimentation is conducted for various pitch to diameter (p/d = 1.18, 1.97, 3.94). The numerical and experimental results show improvement in heat transfer rate as there is decrease in pitch to smooth tube diameter ratio (p/d) and it also increases the value of friction factor. The reason behind the improvement in heat transfer rate is that, the braking of thermal boundary layer near the wall surface. Experimental results show the enhancement of Nusselt number from 3.46 – 6.7.

Keywords

Conical Offset Vortex Generator (COVG), Convective Heat Transfer Coefficient, Angle of Attack, Pitch to Diameter Ratio

References

• [1] Kakac S, Bergles AE, Mayinger F, Yüncü H. Heat Transfer Enhancement of Heat Exchanger. Kluwer Academic Publishers Ed.1 TJ263.H425, 1999.
• [2] Webb RL, Hyun KN. Principles of Enhanced Heat Transfer. Taylor & Francis Group Ed.2 TJ260.W36, 2005.
• [3] Dewan A, Mahanta P, Sumithra K. Suresh P. Review of passive heat transfer augmentation techniques. Part A: Journal of Power and Energy 2004;509–27.
• [4] Liu S, Sakr M. A comprehensive review on passive heat transfer enhancements in pipe exchangers. Renewable and Sustainable Energy Reviews 2013;19:64-81.
• [5] Anderson, JD. Computational Fluid Dynamics-The Basics with Applications. McGraw Hill Publication, Sixth Reprint, 2014.
• [6] Fakiri F, Rahmoun K. Unsteady numerical simulation of turbulent forced convection in a rectangular pipe provided with waved porous baffles. Journal of Thermal Engineering 2017;3(5):1466-1477.
• [7] Singh SK, Kumar M, Kumar A, Gautam A, Chamoli S. Thermal and friction characteristics of a circular tube fitted with perforated hollow circular cylinder inserts. Applied Thermal Engineering 2018;130:230-241.
• [8] Deshmukh PW, Vedula RP. Heat transfer and friction factor characteristics of turbulent flow through a circular tube fitted with vortex generator inserts. International Journal of Heat and Mass Transfer 2014;79:551–560.
• [9] Deshmukh PW, Prabhu SV, Vedula RP. Heat transfer enhancement for laminar flow in tubes using curved delta wing vortex generator. Applied Thermal Engineering 2016;106:1415-1426.
• [10] Wang Y, Liu P, Shan F, Liu Z, Liu W. Effect of longitudinal vortex generator on the heat transfer enhancement of a circular tube. Applied Thermal Engineering 2019;148:1018-1028.
• [11] Sarviya RM, Fuskele V. Heat transfer and pressure drop in a circular tube fitted with twisted tape insert having continuous cut edges. Journal of Energy Storage 2018;19:10-14.
• [12] Chokphoemphun S, Pimsarn M, Thianpong C, Promvonge P. Heat transfer augmentation in circular tube with winglet vortex generators. Chinese Journal of Chemical Engineering 2015;23(4):605-614.
• [13] Liu H, Li H, He Y, Chen Z. Heat transfer and flow characteristics in a circular tube fitted with rectangular winglet vortex generators. International Journal of Heat and Mass Transfer 2018;126:989-1006.
• [14] Li P, Liu P, Liu Z, Liu W. Experimental and numerical study on the heat transfer and flow performance for the circular tube fitted with drainage inserts. International Journal of Heat and Mass Transfer 2017;107:686-696.
• [15] Bhuiya MMK, Chowdhury MSU, Shahabuddin M, Saha M, Memon LA. Thermal characteristics in a heat exchanger tube fitted with triple twisted tape inserts. International Communications in Heat and Mass Transfer 2013;47:124-132.
• [16] Bhuiya MMK, Sayem ASM, Islam M, Chowdhury MSU, Shahabuddin M. Performance assessment in a heat exchanger tube fitted with double counter twisted tape inserts. International Communications in Heat and Mass Transfer 2014;50:25-33.
• [17] Promvonge P, Koolnapadol N, Pimsarn M, Thianpong C, Thermal performance enhancement in a heat exchanger tube fitted with inclined vortex rings. Applied Thermal Engineering 2014;62:285-292.
• [18] Chamoli S, Lu R, Yu P, Thermal characteristic of a turbulent flow through a circular tube fitted with perforated vortex generator inserts. Applied Thermal Engineering 2017;121:1117-1134.
• [19] Incropera FP, Witt PD, Bergman TL, Lavine AS, Fundamentals of Heat and Mass Transfer. John-Wiley & Sons, 2006.
• [20] Launder BE, Spaldling DB, Lectures Notes in Mathematical Models of Turbulence. Academic Press, London, 1972.
• [21] Nalavade SP, Prabhune CL, Sane NK, Effect of novel flow divider type turbulator on fluid flow and heat transfer. Thermal Science and Engineering Progress 2019;9:322-331.