New correlations for wavy plate-fin heat exchangers: different working fluids Morteza Khoshvaght Aliabadi, Faramarz Hormozi and Elham Hosseini Rad School of Chemical, Petroleum and Gas Engineering, Semnan University, Semnan, Iran Abstract Purpose – The main purpose of this paper is the generation of the heat transfer and pressure drop correlations by considering three working fluids, namely air, water, and ethylene glycol, for the wavy plate-fin heat exchangers (PFHEs). Design/methodology/approach – In order to present the general correlations, various models with different geometrical parameters should be tested. Because of the problems, such as difficult, long time, and costly fabrication of the wavy fins in experimental tests, computational fluid dynamics (CFD) calculations can be a useful method for the generation of the heat transfer and pressure drop correlations with eliminating the experimental problems. Hence, the effective design parameters of the wavy plate-fin, including fin pitch, fin height, wave length, fin thickness, wave amplitude, and fin length, and also their levels were recognized from the literature. The Taguchi method was applied to formulate the CFD simulation work. Findings – The simulation results were compared and validated with an available experimental data. The mean deviations of the Colburn factor, j , and Fanning friction factor, f, values between the simulation results and the experimental data were 3.74 and 9.07 percent, respectively. The presented air correlations and experimental data were in a good agreement, so that approximately 95 percent of the experimental data were correlated within 712 percent. The j factor values varied for the different working fluids, while the f factor values did not sensibly change. Practical implications – The presented correlations can be used to estimate the thermal-hydraulic characteristics and to design of the compact PFHE with the wavy channels. Originality/value – This manuscript presents the new correlations for the compact PFHEs with the way channels by considering all the geometrical parameters and the working fluids with the different Prandtl numbers, 0.7, 7, and 150. Keywords CFD simulation, Compact heat exchanger, j and f factor correlation, Prandtl number, Wavy plate-fins Paper type Research paper The current issue and full text archive of this journal is available at www.emeraldinsight.com/0961-5539.htm Received 4 September 2012 Revised 14 April 2013 Accepted 3 May 2013 International Journal of Numerical Methods for Heat & Fluid Flow Vol. 24 No. 5, 2014 pp. 1086-1108 r Emerald Group Publishing Limited 0961-5539 DOI 10.1108/HFF-09-2012-0195 Nomenclature a area (mm 2 ) 2A twice of wavy fin amplitude (mm) C p specific heat of the fluid ( J/kg K) D e hydraulic diameter (m) E total energy (W) F h fin height (mm) F p fin pitch (mm) f Fanning friction factor (DPD e /2rU 2 L) h heat transfer coefficient (W/m 2 K) j Colburn factor (hPr 2/3 /rUC p ) K turbulence kinetic energy (m 2 /s 2 ) L wave length (mm) L d fin length (mm) Nu Nusselt number (hD e /k f ) P pressure (Pa) Dp pressure drop in flow direction (Pa) Pr Prandtl number (mC p /k f ) Re Reynolds number (rUD e /m) T temperature (K) t fin thickness (mm) 1086 HFF 24,5