Model Garcia-Fair

With a more mechanistic model for predicting tray point efficiency, Garcia and Fair showed a better fit to a large database than did the older Chan-Fair model. A parity plot for the Garcia-Fair work is given in Figure 12.64. The newer method is more complex, however, and requires a fairly elaborate computer program. 

The Chan and Fair correlation generally gave good predictions when tested against a wide data bank, but its authors also observed some deviations. Its authors described it as "tentative until more data become available. The Chan and Fair correlation is considered the most reliable fundamental correlation for tray efficiency, but even this correlation has been unable to rectify several theoretical and practical limitations inherited from the AIChE correlation (see Kister, Disfiliation Design, McGraw-Hill, New York, 1992). Recently, Garcia and Fair (Ind. Eng. Chem. Res. 39, 1818, 2000) proposed a more fundamental and accurate model that is also more complicated to apply. 

The FRI data for dualflow trays have been used to form a tentative design method (Garcia and Fair, 2002). Data for Turbogrid trays have been included in the model. A generalized chart for predicting allowable vapor velocity, similar to that for cross flow trays given in Fig. 13.32(b), is included. 

The character of the two-phase mixtnre above the tray floor is different from that of a conventional crossflow tray becanse of the connterflow of the phases, and this makes it possible for a counterflow tray to achieve more than one theoretical stage. A paper by Garcia and Fair provides approaches to modeling pressure drop and efficiency of dualflow trays, based on the FRI database. 

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See also in sourсe #XX -- [ ]

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