Three-dimensional numerical study on fin-and-oval-tube heat exchanger with longitudinal vortex generators

Abstract Three-dimensional numerical study was performed for heat transfer characteristics and fluid flow structure of fin-and-oval-tube heat exchangers with longitudinal vortex generators (LVGs). For Re (based on the hydraulic diameter) ranges from 500 to 2500, it was found that the average Nu for the three-row fin-and-oval-tube heat exchanger with longitudinal vortex generators increased by 13.6–32.9% over the baseline case and the corresponding pressure loss increased by 29.2–40.6%. The results were analyzed on the basis of the field synergy principle to provide fundamental understanding of the relation between local flow structure and heat transfer augmentation. It was confirmed that the reduction of the intersection angle θ between the velocity field and the temperature field was one of the essential factors influencing heat transfer enhancement. Three geometrical parameters – placement of LVGs (upstream and downstream), angles of attack (α = 15°, 30°, 45° and 60°) and tube-row number (n = 2, 3, 4 and 5) – were also investigated for parameter optimization. The LVGs with placement of downstream, angles of attack α = 30° and minimum tube-row number provide the best heat transfer performance. The effects of the three geometrical parameters on heat transfer enhancement were also analyzed from the view point of the field synergy principle and it was found that the results can be well explained by the field synergy principle.

[1]  S. Lee,et al.  Heat transfer in a three-dimensional turbulent boundary layer with longitudinal vortices , 1999 .

[2]  Anthony M. Jacobi,et al.  Heat Transfer Enhancement by Delta-Wing-Generated Tip Vortices in Flat-Plate and Developing Channel Flows , 2002 .

[3]  Min Zeng,et al.  Numerical Verification of the Field Synergy Principle for Turbulent Flow , 2004 .

[4]  Wen-Quan Tao,et al.  Field synergy principle for enhancing convective heat transfer--its extension and numerical verifications , 2002 .

[5]  Wen-Quan Tao,et al.  Three-Dimensional Numerical Simulation on Laminar Heat Transfer and Fluid Flow Characteristics of Strip Fin Surface With X-Arrangement of Strips , 2004 .

[6]  Zhiguo Qu,et al.  NUMERICAL DESIGN OF EFFICIENT SLOTTED FIN SURFACE BASED ON THE FIELD SYNERGY PRINCIPLE , 2004 .

[7]  Wen-Quan Tao,et al.  A unified analysis on enhancing single phase convective heat transfer with field synergy principle , 2002 .

[8]  R. Shah,et al.  Heat transfer surface enhancement through the use of longitudinal vortices: a review of recent progress , 1995 .

[9]  Tong-Miin Liou,et al.  Heat Transfer and Fluid Flow in a Square Duct With 12 Different Shaped Vortex Generators , 2000 .

[10]  P.M.V. Subbarao,et al.  Experimental study of the effect of winglet location on heat transfer enhancement and pressure drop in fin-tube heat exchangers , 2005 .

[11]  M. Fiebig.  Embedded vortices in internal flow: heat transfer and pressure loss enhancement , 1995 .

[12]  Anthony M. Jacobi,et al.  Air-side heat transfer enhancement of a refrigerator evaporator using vortex generation , 2005 .

[13]  M. Fiebig,et al.  Heat transfer enhancement of finned oval tubes with staggered punched longitudinal vortex generators , 2000 .

[14]  Ming Wu,et al.  Improvement of the thermal performance of pulse tube refrigerator by using a general principle for enhancing energy transport and conversion processes , 2004 .

[15]  Vinayak Eswaran,et al.  Heat transfer enhancement in cross-flow heat exchangers using oval tubes and multiple delta winglets , 2003 .

[16]  James E. O'Brien,et al.  Local Heat Transfer and Pressure Drop for Finned-Tube Heat Exchangers Using Oval Tubes and Vortex Generators , 2001, Heat Transfer: Volume 1 — Fundamentals of Heat Transfer.

[17]  Jiin-Yuh Jang,et al.  Heat transfer and fluid flow analysis in plate-fin and tube heat exchangers with a pair of block shape vortex generators , 2004 .

[18]  Koichi Nishino,et al.  Heat transfer enhancement accompanying pressure-loss reduction with winglet-type vortex generators for fin-tube heat exchangers. , 2002 .

[19]  S. Lau,et al.  Measurement of momentum and heat transport in the turbulent channel flow with embedded longitudinal vortices , 1999 .

[20]  Gautam Biswas,et al.  A note on the flow and heat transfer enhancement in a channel with built-in winglet pair , 2007 .

[21]  Gautam Biswas,et al.  Heat transfer and flow structure in laminar and turbulent flows in a rectangular channel with longitudinal vortices , 1995 .

[22]  A. London,et al.  Compact heat exchangers , 1960 .

[23]  Koichi Nishino,et al.  Numerical and experimental determination of flow structure and heat transfer effects of longitudinal vortices in a channel flow , 1996 .

[24]  Anthony M. Jacobi,et al.  A Numerical Study of Flow and Heat Transfer Enhancement Using an Array of Delta-Winglet Vortex Generators in a Fin-and-Tube Heat Exchanger , 2007 .

[25]  M. Fiebig,et al.  Numerical investigation of turbulent flows and heat transfer in a rib-roughened channel with longitudinal vortex generators , 1995 .

[26]  M. Fiebig,et al.  Conjugate heat transfer of a finned oval tube with a punched longitudinal vortex generator in form of a delta winglet—parametric investigations of the winglet , 1998 .

[27]  M. Fiebig,et al.  Heat transfer enhancement of a finned oval tube with punched longitudinal vortex generators in-line , 1998 .

[28]  Bu-Xuan Wang,et al.  A novel concept for convective heat transfer enhancement , 1998 .

[29]  Patrice Tochon,et al.  Intensification of heat-transfer and mixing in multifunctional heat exchangers by artificially generated streamwise vorticity , 2006 .