Mixed Convection and Entropy Generation in a Double-Pipe Heat Exchanger Using Hybrid Nanofluids and Helical Baffles

Ahmed Hassan

doi:10.71229/gep31t82

Authors

Ahmed Hassan Mohammed Department of Mechanical Engineering, College of Engineering, University of Qom, Iran.

DOI:

https://doi.org/10.71229/gep31t82

Keywords:

Entropy Generation, , Hybrid Nanofluids; , Mixed Convection; , Numerical and Experimental Validation

Abstract

This paper reports a complete numerical and experimental study of mixed convection heat transfer and entropy generation in a double pipe heat exchanger working under the effect of hybrid nanofluids and inserted helical baffles. The working fluid is water-based hybrid nanofluids, including multi-walled carbon nanotubes and alumina nanoparticles (MWCNT-Al₂O₃) which are used to enhance thermal conductivity and overall heat transfer efficiency. A three-dimensional computational fluid dynamics (CFD) model is developed and solved using finite volume methods, and experimental data are collected to validate the numerical predictions. The influence of Reynolds number, nanoparticle volume concentrations and geometrical configurations of the helical baffles on the Nusselt number, friction factor and total entropy generation is analyzed in detail. Moreover, recent developments in thermophysical modeling show that hybrid suspensions possess better stability and convective transport abilities under high temperature gradients. The results show the considerable enhancement of the thermal performance of hybrid nanofluids with inserted helical baffles as compared with conventional base fluids. Finally, the total entropy generation reduces significantly at the optimum nanoparticle concentrations, thereby confirming the thermodynamic superiority of the proposed system.

References

[1] S. a. E. J. Choi, "Enhancing thermal conductivity of fluids with nanoparticles.," ASME Fluids Engineering Division, vol. 231, pp. pp.99-105., 1995.

[2] R. a. S. D. Shah, Fundamentals of Heat Exchanger Design, New York.: John Wiley & Sons, 2003.

[3] J. Buongiorno, " Convective transport in nanofluids: a review," Journal of Heat Transfer, vol. 128, no. 3, pp. pp.240-250., 2006.

[4] S. Eiamsa, "3D numerical simulation of heat transfer and flow friction in a circular tube fitted with helical tape inserts," International Communications in Heat and Mass Transfer, vol. 37, no. 7, pp. 112-130, 2010.

[5] P. Garg, " A review on application of nanofluids in heat exchangers," Renewable and Sustainable Energy Reviews, vol. 81, pp. pp.2393-2415. , 2018 .

[6] M. Esfe, " Thermal conductivity of MWCNT-Al2O3 hybrid nanofluids.," International Communications in Heat and Mass Transfer, Vols. 66,, pp. pp.1-7., 2015.

[7] K. a. V. K. Khanafer, "A critical synthesis of thermophysical characteristics of nanofluids.," International Journal of Heat and Mass Transfer, vol. 54, no. 19, pp. pp.4410-4428., 2011.

[8] A. Bejan, Entropy Generation Minimization: The Method of Thermodynamic Optimization of Finite-Size Systems and Finite-Time Processes., New York.: CRC Press, 1996.

[9] O. K Mahian, "Entropy generation during nanofluid flow in heat exchangers: a review.," International Journal of Heat and Mass Transfer, pp. pp.572-593., 2013.

[10] S. P. A. a. Z. L. Kakaç, "Kak A review of numerical studies on convective heat transfer of nanofluids.," International Journal of Thermal Sciences, vol. 55, pp. pp.1-15, 2012.

[11] P. Promvonge, "Heat transfer and pressure drop in a circular tube fitted with helical twisted tapes.," International Communications in Heat and Mass Transfer, vol. 39, no. 8, pp. pp.1118-1124., 2012.

[12] A. Tiwari, "Heat transfer and pressure drop in a heat exchanger with nanofluids.," Applied Thermal Engineering,, vol. 77, pp. pp.30-41., 2015.

[13] R. Shah, Fundamentals of Heat Exchanger Design., New York.: John Wiley & Sons, 2003..

[14] S. Devi, " Numerical investigation of hydromagnetic hybrid nanofluid flow over a stretching sheet with convective boundary condition," International Journal of Engineering Research in Africa, vol. 25, pp. pp.1-13. , 2016.

[15] H. Patel, "Thermal conductivity variations in base fluids with nanoparticle dispersions.," Applied Physics Letters, vol. 83, no. 14, pp. pp.2931-2933., 2003.

[16] L. Sundar, ". MWCNT}-Fe3O4 hybrid nanofluid thermal properties and convection. Journal of Manufacturing Processes," Journal of Manufacturing Processes, vol. 28, pp. , pp.277-287., 2017.

[17] G. Moldoveanu, " Mixed convection heat transfer in vertical channels with nanofluids," Thermal Science, vol. 42, no. 2, pp. pp.789-802., 2020.

[18] J. Zhai, " Multi-objective optimization of a double-pipe heat exchanger using hybrid nanofluids.," Energy, vol. 221, p. p.119850., 2021.

[19] A. Kumar, "Entropy generation minimization in double-pipe heat exchangers.," .Renewable Energy, vol. 135, pp. pp.800-815., 2019.

[20] M. Nazari, "Numerical investigation of turbulent flow and heat transfer of hybrid nanofluids.," Numerical Heat Transfer, vol. 73, no. 5, pp. pp.310-325., 2018.

[21] A. Noghrehabadi, "Heat transfer characteristics of hybrid nanofluids in porous media.," Transport in Porous Media, vol. 114, no. 2, pp. pp.455-472., 2016.

[22] A. Alrashed, "Numerical study of entropy generation in nanofluid flows.," Journal of Thermal Analysis and Calorimetry,, vol. 135, pp. pp.1205-1218., 2020.

[23] J. Holman, Experimental Methods for Engineers, New York.: McGraw-Hill, 2010.

[24] S. V. K. S. P. e. a. Suresh, "Synthesis of Al2O3-Cu/water hybrid nanofluid using a two-step method and its thermophysical properties.," Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 388, no. 3, 2011.

[25] X. a. M. A. Wang, "Heat transfer characteristics of nanofluids: a review.," International Journal of Thermal Sciences, vol. 46, no. 1, pp. pp.1-19, 2007.

[26] G. a. H. A. Huminic, "Hybrid nanofluids in heat transfer equipment – a state-of-the-art review.," International Journal of Heat and Mass Transfer, vol. 125, pp. pp.82-103., 2018.

[27] M. Rashidi, "Entropy generation analysis in nanofluid flows: a review.," International Journal of Heat and Mass Transfer, , vol. 120, pp. pp.770-798., 2018.

[28] S. Ahmed, " Thermal performance of double-pipe heat exchangers using hybrid nanofluids.," Applied Thermal Engineering, vol. 150, pp. pp.450-462., 2019.

[29] S. Verma, ". Performance of hybrid nanofluids in double pipe heat exchanger.," Experimental Thermal and Fluid Science, vol. 91, pp. pp.308-319., 2018.

[30] J. Buongiorno, "Convective transport in nanofluids: a review," Journal of Heat Transfer, vol. 128, no. 3, pp. pp.240-250., 2006.

[31] A. Haghshenas, "Heat transfer enhancement using twisted tapes and nanofluids.," Experimental Thermal and Fluid Science, vol. 120, p. p.110234., 2021.

[32] M. Zubir, "Application of turbulators in heat exchangers," Renewable and Sustainable Energy Reviews, vol. 150, pp. pp.380-405., 2019.