A model has been developed for predicting the amount of condensate retained as drops on the air-side of heat exchangers operating under dehumidifying conditions. For a coil with a given surface wettability, characterized by the advancing contact angle, the maximum diameter for a retained drop is obtained from a balance between gravitational and surface tension forces. A logarithmic function is used to describe the size-distribution of drops on fins, based on the fraction of fin-area covered by liquid. The volumes of individual drops are calculated by a geometric method for approximating the three-dimensional shapes of drops on vertical and inclined surfaces. The total volume of condensate accumulated on a coil is then found by multiplying the size-distribution and volume functions and integrating over all drop diameters. The model is successful in predicting measurements by other researchers of the mass of condensate retained on plain-fin heat exchangers. The critical fin spacing to avoid the formation of condensate bridges is also predicted.
Issue Section:
Heat Exchangers
1.
Yin
, J.
, and Jacobi
, A. M.
, 2000, “Condensate Retention Effects on the Air-Side Heat Transfer Performance of Plain and Wavy-Louvered Heat Exchangers,” Report No. TR-158, ACRC, University of Illinois at Urbana-Champaign, IL.2.
McQuiston
, F. C.
, 1978, “Heat, Mass, and Momentum Transfer Data for Five Plate-Fin-Tube Heat Transfer Surfaces
,” ASHRAE Trans.
0001-2505, 84
, pp. 266
–293
.3.
McQuiston
, F. C.
, 1978, “Correlation of Heat, Mass, and Momentum Transport Coefficients for Plate-Fin-Tube Heat Transfer Surfaces with Staggered Tubes
,” ASHRAE Trans.
0001-2505, 84
, pp. 294
–308
.4.
Eckels
, P. W.
, and Rabas
, T. J.
, 1987, “Dehumidification: On the Correlation of Wet and Dry Transport Processes in Plate Finned-Tube Heat Exchangers
,” ASME J. Heat Transfer
0022-1481, 109
, pp. 575
–582
.5.
Wang
, C. C.
, Hsieh
, Y. C.
, and Lin
, Y. T.
, 1997, “Performance of Plate Finned Tube Heat Exchangers Under Dehumidifying Conditions
,” ASME J. Heat Transfer
0022-1481, 119
, pp. 109
–117
.6.
Korte
, C. M.
, and Jacobi
, A. M.
, 2001, “Condensate Retention Effects on the Performance of Plain-Fin-and-Tube Heat Exchangers: Retention Data and Modeling
,” ASME J. Heat Transfer
0022-1481, 123
, pp. 926
–936
.7.
Jacobi
, A. M.
, and Goldschmidt
, V. W.
, 1990, “Low Reynolds Number Heat and Mass Transfer Measurements of an Overall Counterflow, Baffled, Finned-Tube, Condensing Heat Exchanger
,” Int. J. Heat Mass Transfer
0017-9310, 33
, pp. 755
–765
.8.
Wang
, C. C.
, Du
, Y. J.
, Chang
, Y. J.
, and Tao
, W. H.
, 1999, “Airside Performance of Herringbone Fin-and-Tube Heat Exchangers in Wet Conditions
,” Can. J. Chem. Eng.
0008-4034, 77
, pp. 1225
–1230
.9.
Kim
, G. J.
, and Jacobi
, A. M.
, 2000, “Condensate Accumulation Effects on the Air-Side Thermal Performance of Slit-Fin Surfaces
,” Report No. CR-26, ACRC, University of Illinois, Urbana.10.
Beatty
, K. O.
, Jr., and Katz
, D. L.
, 1948, “Condensation of Vapors on Outside of Finned Tubes
,” Chem. Eng. Prog.
0360-7275, 44
, pp. 55
–70
.11.
Rudy
, T. M.
, and Webb
, R. L.
, 1985, “An Analytical Model to Predict Condensate Retention on Horizontal Integral-Fin Tubes
,” ASME J. Heat Transfer
0022-1481, 107
, pp. 361
–368
.12.
Brown
, R. A.
, Orr
, F. M.
, Jr., and Scriven
, L. E.
, 1980, “Static Drop on an Inclined Plate: Analysis by the Finite Element Method
,” J. Colloid Interface Sci.
0021-9797, 73
, pp. 76
–87
.13.
Milinazzo
, F.
, and Shinbrot
, M.
, 1988, “A Numerical Study of a Drop on a Vertical Wall
,” J. Colloid Interface Sci.
0021-9797, 121
, pp. 254
–264
.14.
Rotenberg
, Y.
, Boruvka
, L.
, and Neumann
, A. W.
, 1984, “The Shape of Nonaxisymmetric Drops on Inclined Planar Surfaces
,” J. Colloid Interface Sci.
0021-9797, 102
, pp. 424
–434
.15.
Dimitrakopoulos
, P.
, and Higdon
, J. J. L.
, 1999, “On the Gravitational Displacement of Three-Dimensional Fluid Droplets from Inclined Solid Surfaces
,” J. Fluid Mech.
0022-1120, 395
, pp. 181
–209
.16.
ElSherbini
, A. I.
, 2003, “Modeling Condensate Drops Retained on the Air-Side of Heat Exchangers
,” Ph.D. thesis, University of Illinois at Urbana-Champaign, IL.17.
ElSherbini
, A. I.
, and Jacobi
, A. M.
, 2004, “Liquid Drops on Vertical and Inclined Surfaces: Part II—A Method for Approximating Drop Shapes
,” J. Colloid Interface Sci.
0021-9797, 273
, pp. 566
–575
.18.
ElSherbini
, A. I.
, and Jacobi
, A. M.
, 2004, “Liquid Drops on Vertical and Inclined Surfaces: Part I—An Experimental Study of Drop Geometry
,” J. Colloid Interface Sci.
0021-9797, 273
, pp. 556
–565
.19.
ElSherbini
, A. I.
, and Jacobi
, A. M.
, 2005, “Retention Forces and Contact Angles for Critical Liquid Drops on Non-Horizontal Surfaces
,” J. Colloid Interface Sci.
(in press).20.
Graham
, C.
, 1969, “The Limiting Heat Transfer Mechanisms of Dropwise Condensation
,” Ph.D. thesis, Massachusetts Institute of Technology, MA.21.
Graham
, C.
, and Griffith
, P.
, 1973, “Drop Size Distributions and Heat Transfer in Dropwise Condensation
,” Int. J. Heat Mass Transfer
0017-9310, 16
, pp. 337
–346
.22.
Tanasawa
, I.
, and Ochiai
, J.
, 1973, “Experimental Study on Dropwise Condensation
,” Bull. JSME
0021-3764, 16
, pp. 1184
–1197
.23.
Tanaka
, H.
, 1975, “Measurements of Drop-Size Distributions During Transient Dropwise Condensation
,” ASME J. Heat Transfer
0022-1481, 97
, pp. 341
–346
.24.
Sugawara
, S.
, and Michiyoshi
, I.
, 1956, “Dropwise Condensation
,” Mem. Fac. Eng., Kyoto Univ.
0023-6063, Kyoto University, 18
, pp. 84
–111
.25.
Wu
, Y. T.
, Yang
, C. X.
, and Yuan
, X. G.
, 2001, “Drop Distributions and Numerical Simulation of Dropwise Condensation Heat Transfer
,” Int. J. Heat Mass Transfer
0017-9310, 44
, pp. 4455
–4464
.26.
Rose
, J. W.
, and Glicksman
, L. R.
, 1973, “Dropwise Condensation–The Distribution of Drop Sizes
,” Int. J. Heat Mass Transfer
0017-9310, 16
, pp. 411
–425
.27.
Shin
, J.
, and Ha
, S.
, 2002, “The Effect of Hydrophilicity on Condensation Over Various Types of Fin-And-Tube Heat Exchangers
,” Int. J. Refrig.
0140-7007, 25
, pp. 688
–694
.28.
Korte
, C. M.
, and Jacobi
, A. M.
, 1997, “Condensate Retention and Shedding Effects on Air-Side Heat Exchanger Performance
,” Report No. TR-132, ACRC, University of Illinois, Urbana.Copyright © 2006
by American Society of Mechanical Engineers
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