Surprising effects of combined vapour and liquid mass transfer resistances when condensing a mixture outside tube banks

Detailed calculations are carried out for condensation of a binary zeotropic mixture outside a tube bank to investigate combined effects of mass transfer resistances in the liquid and vapour phases. The question is how a change in mass transfer resistance in the vapour phase can influence the heat flux. The surprising result is that a decrease in resistance in the vapour phase by reducing the tube pitch, and thus increasing the vapour velocity, reduces the heat flux between 20% and 50% for the conditions studied. This is due to a combination of mass transfer resistance, depletion of the heavy volatile component, and a reduction of the phase interface temperature.

[1]  J. Thome,et al.  Convective Boiling and Condensation , 1972 .

[2]  A. Colburn,et al.  Mass Transfer (Absorption) Coefficients Prediction from Data on Heat Transfer and Fluid Friction , 1934 .

[3]  Tord Karlsson,et al.  Reasons for drop in shell-and-tube condenser performance when replacing R22 with zeotropic mixtures. Part 1. Analysis of experimental findings , 2004 .

[4]  Lennart Vamling,et al.  Reasons for drop in shell-and-tube condenser performance when replacing R22 with zeotropic mixtures. Part 2: investigation of mass transfer resistance effects , 2004 .

[5]  André Bontemps,et al.  Condensation heat transfer of a pure fluid and binary mixture outside a bundle of smooth horizontal tubes. Comparison of experimental results and a classical model , 2001 .

[6]  N. Takata,et al.  Experimental measurements for condensation of downward-flowing R123/R134a in a staggered bundle of horizontal low-finned tubes with four fin geometries , 1999 .

[7]  M. McLinden,et al.  NIST Standard Reference Database 23 - NIST Thermodynamic and Transport Properties REFPROP, Version 7.0 , 2002 .

[8]  D. Yung,et al.  Vapor/Liquid Interaction and Entrainment in Falling Film Evaporators , 1980 .

[9]  C. Gabrielii,et al.  Replacement of R22 in tube-and-shell condensers: experiments and simulations , 1997 .

[10]  Davide Del Col,et al.  Condensation inside and outside smooth and enhanced tubes: a review of recent research , 2003 .

[11]  Dongsoo Jung,et al.  Condensation heat transfer coefficients of halogenated binary refrigerant mixtures on a smooth tube , 2003 .

[12]  Ross Taylor,et al.  Multicomponent mass transfer , 1993 .

[13]  Anthony M. Jacobi,et al.  The intertube falling film: Part 1 - Flow characteristics, mode transitions, and hysteresis , 1996 .

[14]  J. Giddings,et al.  NEW METHOD FOR PREDICTION OF BINARY GAS-PHASE DIFFUSION COEFFICIENTS , 1966 .

[15]  N. Takata,et al.  Condensation of downward-flowing zeotropic mixture HCFC-123/HFC-134a on a staggered bundle of horizontal low-finned tubes , 1997 .

[16]  G. Fulford.  The Flow of Liquids in Thin Films , 1964 .

[17]  André Bontemps,et al.  Experimental study and modelling of heat transfer during condensation of pure fluid and binary mixture on a bundle of horizontal finned tubes , 2003 .

[18]  A. Jacobi,et al.  Departure-site spacing for liquid droplets and jets falling between horizontal circular tubes , 1998 .

[19]  K. Lucas,et al.  Correlations for prediction of diffusion in liquids , 1986 .

[20]  K. Stephan.  Heat Transfer in Condensation and Boiling , 1992 .

[21]  T. B. Drew,et al.  The condensation of mixed vapors , 1965 .

[22]  Dongsoo Jung,et al.  Condensation heat transfer coefficients of R22, R407C, and R410A on a horizontal plain, low fin, and turbo-C tubes , 2003 .