Flow, heat transfer, and pressure drop in the near-wall region of louvered-fin arrays

Abstract Using the naphthalene sublimation technique and complementary flow visualization, the effects of bounding walls on flow and heat transfer in louvered-fin arrays are studied. Results for spatially periodic flow far from the walls are compared to results for the near-wall flow, where the impact of the bounding surface is important. In contrast to flow in the spatially periodic region, the near-wall flow is characterized by large separation zones between the louvers, and unsteadiness is manifest at much lower Reynolds numbers than in the spatially periodic region. At low Reynolds numbers (Re≈600 and below in this study) the large separation zones cause a decrease in heat transfer of up to 50%. However, if the Reynolds number is high enough to promote unsteady flow near the wall, the net effect is to locally increase heat transfer by up to approximately 15% (at Re=1400). Unfortunately, this increased heat transfer is accompanied by a several hundred percent increase in pressure drop. A formula for characterizing the spatial extent of these wall effects is presented.

[1]  Chi-Chuan Wang,et al.  A generalized heat transfer correlation for Iouver fin geometry , 1997 .

[2]  Ralph L. Webb,et al.  How structure in the louvered fin heat exchanger geometry , 1991 .

[3]  Anthony M. Jacobi,et al.  Localized flow and heat transfer interactions in louvered-fin arrays , 2003 .

[4]  Y. N. Lee.  Heat transfer and pressure drop characteristics of an array of plates aligned at angles to the flow in a rectangular duct , 1986 .

[5]  R. J. Goldstein,et al.  A review of mass transfer measurements using naphthalene sublimation , 1995 .

[6]  Ralph L. Webb,et al.  Rationally Based Heat Transfer and Friction Correlations for the Louver Fin Geometry , 1994 .

[7]  P. Mendes,et al.  The naphthalene sublimation technique , 1991 .

[8]  E. Sparrow,et al.  Measurements of heat transfer and pressure drop for an array of staggered plates aligned parallel to an air flow , 1980 .

[9]  K. D. Bellows.  Flow Visualization of Louvered-Fin Heat Exchangers , 1997 .

[10]  Karen A. Thole,et al.  Experimental design for flowfield studies of louvered fins , 1998 .

[11]  Debashis Ghosh,et al.  Applied CFD and experiment for automotive compact heat exchanger development , 1998 .

[12]  Ralph L. Webb,et al.  Prediction of Heat Transfer and Friction for the Louver Fin Geometry , 1992 .

[13]  Zhang Huihua,et al.  The experimental investigation of oblique angles and interrupted plate lengths for louvered fins in compact heat exchangers , 1989 .

[14]  T. A. Cowell,et al.  Heat transfer and pressure drop characteristics of flat tube and louvered plate fin surfaces , 1988 .

[15]  Chi-Chuan Wang,et al.  Air Side Performance of Brazed Aluminum Heat Exchangers , 1996 .

[16]  Wen-Quan Tao,et al.  An experimental study on heat/mass transfer and pressure drop characteristics for arrays of nonuniform plate length positioned obliquely to the flow direction , 1993 .

[17]  C. J. Davenport.  Heat Transfer and Flow Friction Characteristics of Louvred Heat Exchanger Surfaces , 1981 .

[18]  N. C. Dejong,et al.  An experimental study of flow and heat transfer in parallel-plate arrays: Local, row-by-row and surface average behavior , 1997 .

[19]  S. J. Kline,et al.  Describing Uncertainties in Single-Sample Experiments , 1953 .

[20]  W. Tao,et al.  Experimental study on heat transfer and pressure drop characteristics in the developing region for arrays of obliquely positioned plates of nonuniform length , 1993 .

[21]  Hiroshi Aoki,et al.  Numerical Analysis on Two-Dimensional Flow and Heat Transfer of Louvered Fins Using Overlaid Grids , 1990 .

[22]  Naim Afgan,et al.  Heat Exchangers Theory Amp Practice , 1983 .