Document Type : Full length


Department of Chemical Engineering, Faculty of Engineering, University of Kurdistan, Sanandaj, Iran


In the study, the thermal-hydraulic performance of the zigzag channels with circular cross-section was analyzed by Computational Fluid Dynamics (CFD). The standard K-Ꜫ turbulent scalable wall functions were used for modeling. The wall temperature was assumed constant 353 K and water was used as the working fluid. The zigzag serpentine channels with bend angles of 5 - 45° were studied for turbulent flow from 4000 to 40,000 Reynolds number (Re). The thermal performance of the zigzag 45° channel was better than the other channels and also it had the highest friction factor (f). The bends caused secondary flow, and as the bend angle increased, the secondary flow increased. This Phenomenon had a positive effect on thermal performance and a negative effect on hydraulic performance by increasing the friction factor. The obtained CFD data used to develop correlations for predicting the Nu and f as the functions of Re and bend angles. The correlation constants were optimized by the genetic algorithm method which leads to the mean relative errors of 3.32% and 6.94% for Nu and f estimation, respectively.


[1]     Beigzadeh, R., Parvareh, A. and Rahimi, M., “Experimental and CFD study of the tube configuration effect on the shell-side thermal performance in a shell and helically coiled tube heat exchanger”, Iran J. Chem. Eng., 12 (2), 13 (2015).
[2]     Karale, C. M., Bhagwat, S. S. and Ranade, V. V., "Flow and heat transfer in serpentine channels", AIChE J., 59 (5), 1814 (2013).
[3]     Ozbolat, V., Tokgoz, N. and Sahin, B., “Flow characteristics and heat transfer enhancement in 2D corrugated channels”, Int. J. Mech. Sci. Eng., 7 (10), 796 (2013).
[4]     Arvanitis, K. D., Bouris, D. and Papanicolaou, E., “Laminar flow and heat transfer in U-bends: The effect of secondary flows in ducts with partial and full curvature”, Int. J Therm. Sci., 130, 70 (2018).
[5]     Takamura, H., Ebara, S., Hashizume, H., Aizawa, K. and Yamano, H., “Flow visualization and frequency characteristics of velocity fluctuations of complex turbulent flow in a short elbow piping under high Reynolds number condition”, J. Fluids Eng., 134 (10), 101201 (2012)
[6]     Kim, J., Yadav, M. and Kim, S., “Characteristics of secondary flow induced by 90-degree elbow in turbulent pipe flow”, Eng. Appl. Comp. Fluid Mech., 8 (2), 229 (2014).
[7]     Sheikholeslami, M., Gerdroodbary, M. B., Mousavi, S. V., Ganji, D. D. and Moradi, R. “Heat transfer enhancement of ferrofluid inside an 90 elbow channel by non-uniform magnetic field”, J. Magn. Magn. Mater, 460, 302 (2018).
[8]     Naphon, P. and Wongwises, S., “A review of flow and heat transfer characteristics in curved tubes”, Renew. Sustain. Energy Rev., 10 (5), 463 (2006).
[9]     Wang, J., Wang, S., Zhang, T. and Battaglia, F., “Numerical and analytical investigation of ice slurry isothermal flow through horizontal bends”, Int. J. Refrig., 92, 37 (2018).
[10]  Kalpakli, A. and Örlü, R., “Turbulent pipe flow downstream a 90 pipe bend with and without superimposed swirl”, Int. J. Heat Fluid Flow, 41, 103 (2013).
[11]  Khoshvaght-Aliabadi, M., Khaligh, S. F. and Tavassoli, Z., “An investigation of heat transfer in heat exchange devices with spirally-coiled twisted-ducts using nanofluid”, Appl. Therm. Eng., 143, 358 (2018).
[12]  Ngo, T. L., Kato, Y., Nikitin, K. and Ishizuka, T., “Heat transfer and pressure drop correlations of microchannel heat exchangers with S-shaped and zigzag fins for carbon dioxide cycles”, Exp. Therm. Fluid Sci., 32 (2), 560 (2007).
[13]  Zheng, Z., Fletcher, D. F. and Haynes, B. S., “Chaotic advection in steady laminar heat transfer simulations: Periodic zigzag channels with square cross-sections”, Int. J. Heat Mass Transf., 57 (1), 274 (2013).
[14]  Moraveji, M. K. and Beheshti, A. R., “CFD study of the turbulent forced convective heat transfer of non-newtonian nanofluid”, Iran J. Chem. Eng., 11 (2), 92 (2014).
[15]  Beigzadeh, R., “The CFD provides data for adaptive neuro-fuzzy to model the heat transfer in flat and discontinuous fins”, Iran J. Chem. Eng., 16 (2), 57 (2019).
[16]  Cui, X., Guo, J., Huai, X., Zhang, H., Cheng, K. and Zhou, J., “Numerical investigations on serpentine channel for supercritical CO2 recuperator”, Energy, 172, 517 (2019).
[17]  Rahimi, M., Shabanian, S. R. and Alsairafi, A. A., “Experimental and CFD studies on heat transfer and friction factor characteristics of a tube equipped with modified twisted tape inserts”, Chem. Eng. Process, 48 (3), 762 (2009).
[18]  Taler, D. and Taler, J., “Simple heat transfer correlations for turbulent tube flow”, In E3S Web of Conferences, EDP Sciences, Vol. 13, 02008 (2017).
[19]  Ahsan, M., “Numerical analysis of friction factor for a fully developed turbulent flow using k–ε turbulence model with enhanced wall treatment”, Beni Suef Univ. J. Basic Appl. Sci., 3 (4), 269 (2014).
[20]  Dutta, P., Saha, S. K., Nandi, N. and Pal, N., “Numerical study on flow separation in 90 pipe bend under high Reynolds number by k-ε modelling”, Eng. Sci. Technol. Int. J., 19 (2), 904 (2016).
[21]  Rahimi, M., Beigzadeh, R., Parvizi, M. and Eiamsa-ard, S., “GMDH-type neural network modeling and genetic algorithm-based multi-objective optimization of thermal and friction characteristics in heat exchanger tubes with wire-rod bundles”, Heat Mass Transf., 52 (8), 1585 (2016).