Analysis of heat transfer and pressure drop for fin-and-tube heat exchangers with rectangular winglet-type vortex generators

Abstract In present work, heat transfer enhancement and pressure loss penalty for fin-and-tube heat exchangers with rectangular winglet pairs (RWPs) were numerically investigated in a relatively low Reynolds number flow. The purpose of this study was to explore the fundamental mechanism between the local flow structure and the heat transfer augmentation. The RWPs were placed with a special orientation for the purpose of enhancement of heat transfer. The numerical study involved three-dimensional flow and conjugate heat transfer in the computational domain, which was set up to model the entire flow channel in the air flow direction. The effects of attack angle of RWPs, row-number of RWPs and placement of RWPs on the heat transfer characteristics and flow structure were examined in detail. It was observed that the longitudinal vortices caused by RWPs and the impingement of RWPs-directed flow on the downstream tube were important reasons of heat transfer enhancement for fin-and-tube heat exchangers with RWPs. It was interesting to find that the pressure loss penalty of the fin-and-tube heat exchangers with RWPs can be reduced by altering the placement of the same number of RWPs from inline array to staggered array without reducing the heat transfer enhancement. The results showed that the rectangular winglet pairs (RWPs) can significantly improve the heat transfer performance of the fin-and-tube heat exchangers with a moderate pressure loss penalty.

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

[2]  Rui Li,et al.  Three-dimensional numerical study on fin-and-oval-tube heat exchanger with longitudinal vortex generators , 2009 .

[3]  Anthony M. Jacobi,et al.  Heat transfer enhancement by winglet-type vortex generator arrays in compact plain-fin-and-tube heat exchangers , 2008 .

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

[5]  Wen-Quan Tao,et al.  Numerical study on laminar convection heat transfer in a rectangular channel with longitudinal vortex generator. Part A: Verification of field synergy principle , 2008 .

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

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

[8]  W. Tao,et al.  Numerical study on laminar convection heat transfer in a channel with longitudinal vortex generator. Part B: Parametric study of major influence factors , 2008 .

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

[10]  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 .

[11]  T. Liou,et al.  Heat Transfer and Fluid Flow in a Square Duct With 12 Different Shaped Vortex Generators , 1999 .

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

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

[14]  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.

[15]  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 .

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

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

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

[19]  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 .

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

[21]  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 .

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

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

[24]  Pan Chu,et al.  Numerical Study of Flow and Heat Transfer Enhancement by Using Delta Winglets in a Triangular Wavy Fin-and-Tube Heat Exchanger , 2009 .

[25]  Pan Chu,et al.  Three-Dimensional Numerical Study of Flow and Heat Transfer Enhancement Using Vortex Generators in Fin-and-Tube Heat Exchangers , 2009 .

[26]  Christopher J. Sutcliffe,et al.  An experimental investigation into the deployment of 3-D, finned wing and shape memory alloy vortex generators in a forced air convection heat pipe fin stack , 2011 .

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

[28]  Ya-Ling He,et al.  A comparative study on the air-side performance of wavy fin-and-tube heat exchanger with punched delta winglets in staggered and in-line arrangements , 2009 .