OPTIMIZATION OF THE LOUVER FIN-AND-TUBE HEAT EXCHANGERS-A PARAMETRIC APPROACH

3D turbulent flow numerical simulations are performed to study heat transfer and flow friction characteristics of louver fin-and-tube heat exchangers. The effects of louver angle, fin pitch, transversal tube pitch, and longitudinal tube pitch on Colburn and friction factors are investigated in detail. Three stages of the effect of louver angle on the Colburn j factor are identified, including rising, level-off, and increasing again. A wide range for louver angle ranging from 0 degrees (plain fin) to 80 degrees is considered. Results show that the Colburn factor increases from a louver angle of 0 degrees (plain fin) to 20 degrees, followed by a level-off or slight decline until the louver angle reaches 45 degrees, and finally, the Colburn factor is increased again with a further rise of louver angle. However, the friction factor increases with an increase in louver angle from 0 degrees (plain fin) to 80 degrees. Colburn and friction factors are almost independent of fin pitch while they decrease with an increase in transversal and longitudinal tube pitches. The optimum louver angle is around 20 degrees upon carrying out the full factorial method in maximizing Colburn factor and minimizing friction factor.