A Comparative Numerical Study of Estimation of Velocity Components in Mixed Convection Through Vertical Shrouded Plate Finned Channel

Abstract

An attempt has been made to investigate the performance of two methods of estimation of free and forced convection velocity components present in mixed convection. For this present analysis, a vertically configured shrouded plate finned channel is considered. From the literature, it is observed that in the solution of mixed convection problems related to the various engineering applications, proper estimation of induced velocity and fan/pump velocity plays a vital role. For this cause, segregation of the velocity components of free and forced convection present in the mixed convection becomes important. There exist two methods available in the literature, namely, first, the natural convection computational fluid dynamics method (NCM) used in the mixed convection computational fluid dynamics analysis under the same thermal and geometrical conditions, and second, forced convection decoupled method (FDM) applying the same pressure drop in forced and mixed convection across the channel. Results of this study reveal that if the free or induced velocity component present in the mixed convection is assessed based on the forced convection decoupled method, the pumping power results may be more precise than the natural convection computational fluid dynamic method as in the later method calculation of the forced convection velocity component is underpredicted. The natural convection velocity component evaluated through NCM varies 33% to 65.7% from the FDM based on the shroud clearance for the constant fin heights of 0.04 m. This variation is as high as 98% and 96% in the case of the larger nondimensional fin spacing of 0.3 and 0.5, respectively. A correlation of overall Nusselt number is suggested for a vertically configured shrouded dualheight plate finned channel evaluating appropriate Reynolds through the forced convection decoupled method.