Heat transfer augmentation in a wedge-ribbed channel using winglet vortex generators

article i nfo Available online 18 October 2009 Experimental investigations have beencarried outtostudy the effect ofcombinedwedgeribs andwinglettype vortex generators (WVGs) on heat transfer and friction loss behaviors for turbulent airflow through a constant heat flux channel. To create a reverse flow in the channel, two types of wedge (right-triangle) ribs are introduced: wedge ribs pointing downstream and pointing upstream. The arrangements of both rib types placedinsidetheoppositechannelwallsarein-lineandstaggeredarrays.Togeneratelongitudinalvortex flows through the tested section, two pairs of the WVGs with the attack angle of 60° are mounted on the test channel entrance. The test channel has an aspect ratio, AR=10 and height, H=30 mm with a rib height, e/H=0.2 and rib pitch,P/H=1.33. The flowrate interms ofReynoldsnumbersisbasedon theinlet hydraulic diameter of the channel ranging from 5000 to 22,000. The presence of the combined ribs and the WVGs shows the significant increase in heat transfer rate and friction loss over the smooth channel. The Nusselt number and friction factor values obtained from combined the ribs and the WVGs are found to be much higher than those from the ribs/ WVGs alone. In conjunction with the WVGs, the in-line wedge pointing downstream provides the highest increase in both the heat transfer rate and the friction factor while the staggered wedge pointing upstream

[1]  Pongjet Promvonge,et al.  Thermal characterization of turbulent flow in a channel with isosceles triangular ribs , 2009 .

[2]  Waion Wong,et al.  Flow and Forced-Convection Characteristics of Turbulent Flow Through Parallel Plates with Periodic Transverse Ribs , 2005 .

[3]  Je-Chin Han,et al.  Influence of Surface Heat Flux Ratio on Heat Transfer Augmentation in Square Channels With Parallel, Crossed, and V-Shaped Angled Ribs , 1992 .

[4]  Pongjet Promvonge,et al.  Heat transfer enhancement in a tube with combined conical-nozzle inserts and swirl generator , 2006 .

[5]  Pongjet Promvonge,et al.  Heat transfer in a circular tube fitted with free-spacing snail entry and conical-nozzle turbulators ☆ , 2007 .

[6]  Giovanni Tanda,et al.  Heat transfer in rectangular channels with transverse and V-shaped broken ribs , 2004 .

[7]  Je-Chin Han,et al.  High performance heat transfer ducts with parallel broken and V-shaped broken ribs , 1992 .

[8]  Y. Jaluria,et al.  An Introduction to Heat Transfer , 1950 .

[9]  S. C. Solanki,et al.  Heat transfer coefficient and friction factor correlations for rectangular solar air heater duct having transverse wedge shaped rib roughness on the absorber plate , 2002 .

[10]  M. Taslim,et al.  Darryl E. Metzger Memorial Session Paper: Experimental Heat Transfer and Friction in Channels Roughened With Angled, V-Shaped, and Discrete Ribs on Two Opposite Walls , 1996 .

[11]  Je-Chin Han,et al.  Heat transfer and friction behaviors in rectangular channels with varying number of ribbed walls , 2003 .

[12]  Pongjet Promvonge,et al.  Heat transfer augmentation in a circular tube using V-nozzle turbulator inserts and snail entry , 2007 .

[13]  Hiroshi Iwai,et al.  NUMERICAL ANALYSIS FOR HEAT TRANSFER CHARACTERISTICS OF AN OBLIQUE DISCRETE RIB MOUNTED IN A SQUARE DUCT , 2003 .

[14]  M. Taslim,et al.  EXPERIMENTAL HEAT TRANSFER AND FRICTION IN CHANNELS ROUGHENED WITH ANGLED, V-SHAPED AND DISCRETE RIBS ON TWO OPPOSITE WALLS , 1994 .

[15]  P. Promvonge,et al.  Thermal performance assessment of turbulent channel flows over different shaped ribs , 2008 .

[16]  Varun,et al.  A review on roughness geometry used in solar air heaters , 2007 .

[17]  Arash Saidi, Bengt SundÉn.  NUMERICAL SIMULATION OF TURBULENT CONVECTIVE HEAT TRANSFER IN SQUARE RIBBED DUCTS , 2000 .

[18]  Jenn-Jiang Hwang,et al.  Turbulent Heat Transfer Augmentation and Friction in Periodic Fully Developed Channel Flows , 1992 .

[19]  Pongjet Promvonge,et al.  Thermal enhancement in a round tube with snail entry and coiled-wire inserts , 2008 .

[20]  C. P. Lee,et al.  Augmented Heat Transfer in Square Channels With Parallel, Crossed, and V-Shaped Angled Ribs , 1991 .

[21]  Jenn-Jiang Hwang,et al.  Effect of ridge shapes on turbulent heat transfer and friction in a rectangular channel , 1993 .

[22]  Anthony M. Jacobi,et al.  Heat transfer enhancement by delta-wing vortex generators on a flat plate: Vortex interactions with the boundary layer , 1997 .

[23]  Omer Comakli,et al.  Heat transfer and friction characteristics in decaying swirl flow generated by different radial guide vane swirl generators , 2003 .

[24]  P. Promvonge.  Thermal augmentation in circular tube with twisted tape and wire coil turbulators , 2008 .

[25]  Bassam B. Dally,et al.  Effect of a delta-winglet vortex pair on the performance of a tube–fin heat exchanger , 2007 .

[26]  Yue-Tzu Yang,et al.  NUMERICAL CALCULATIONS OF HEAT TRANSFER AND FRICTION CHARACTERISTICS IN RECTANGULAR DUCTS WITH SLIT AND SOLID RIBS MOUNTED ON ONE WALL , 2004 .