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Laminar dispersion in capillaries: Part V. Experiments on combined natural and forced convection in vertical tubes
Author(s) -
Reejhsinghani N. S.,
Barduhn Allen J.,
Gill William N.
Publication year - 1968
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690140119
Subject(s) - laminar flow , dispersion (optics) , mechanics , range (aeronautics) , forced convection , thermodynamics , natural convection , chemistry , convection , materials science , physics , optics , composite material
Abstract An approximate theory for transient dispersion with combined free and forced convection in vertical tubes is developed and tested experimentally. It is found that the dispersion coefficient in such systems depends on a parameter α, which is defined by Equation (38). The analytical expression developed for the dispersion coefficient, Equation (33), is found to be a reasonably good approximation in the range −50 < α < 300. Experimental results are reported for a rather wide range of parameters for tubes with both 1 1/2 and 5 mm. diameters. It is found that the extent of dispersion is enhanced significantly when lighter fluid is on the bottom and displaces a heavier one. On the other hand, the dispersion coefficient is inhibited when the situation is reversed. It is found that these effects are not symmetrical with respect to the absolute magnitude of the parameter α as is illustrated in Figure 12.