Correlation of fractionation tray performance via a cross‐flow boundary‐layer model

“…The purpose of this note is to simplify a correlation given by Young and Stewart (1992) for the hydrodynamic function a, in their sieve-tray heat and mass transport model. They obtained the relation (1) PG P L with 95% probability intervals for the individual parameters.…”

mentioning

confidence: 99%

“…Fitting the resulting new model to the data by the procedure of Young and Stewart (1992), we obtain the simpler relation ( fG2,hw )0.658* 0.038 a , = (0.2753 kO.0097) ~ with more precise parameter estimates. This model is preferable to Eq.…”

mentioning

confidence: 99%

Concise correlation of sieve‐tray heat and mass transfer

Young

Stewart

1995

AIChE Journal

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The purpose of this note is to simplify a correlation given by Young and Stewart (1992) for the hydrodynamic function a, in their sieve-tray heat and mass transport model. They obtained the relation (1)with 95% probability intervals for the individual parameters. The first interval width (k0.0112) in Eq. 1 is a corrected value.The second dimensionless group in Eq. 1 is 50 or greater for the data used, and generally so in practice; hence, the -1 term can be neglected. Doing so, we find that the indicated power of this group is essentially the 0.688 f 0.276 power of a ratio of characteristic gas velocities. Since the latter exponent range brackets that of the Reynolds number ( pG( uG)hw/pL), we can dispose of the second group by basing the gas velocity in the Reynolds number on the open area of the tray rather than on the total or the active projected area.Fitting the resulting new model to the data by the procedure of Young and Stewart (1992), we obtain the simpler relation ( fG2,hw )0.658* 0.038 a , = (0.2753 kO.0097) ~ with more precise parameter estimates. This model is preferable to Eq. 1, since it fits the data comparably well with one parameter less.The point transfer coefficients in a binary two-phase sys- tern on a sieve tray are computable from Eq. 2 and the relations predicted by mobile-interface boundary layer theory at small net mass-transfer rates. Here h, and h,, are heant-transfer coefficients, and CY is the thermal diffusivity (k/pC,) of the given phase. Equations 2-6 summarize the effects of the main variables on the heat-and mass-transfer coefficients for each phase at flow conditions such that weeping and entrainment do not occur; surface-tension-driven flows (Marangoni effects) remain to be considered. Further boundary-layer relations are given for binary systems by Young and Stewart (19921, and for multicomponent nonisothermal systems by Young and Stewart (1990). The linearized boundary-layer approach used in these multicomponent calculations was tested by Young and Stewart (1986) against detailed solutions, and proved more reliable than multicomponent film mass-transfer models. The notation a, denotes the leading coefficient in an asymptotic expansion of the Nusselt or Sherwood number, given by Stewart (1987). This leading coefficient was evaluated formally by Stewart el al. (19701, and explicitly for simple interfacial motions. Dafa-based expressions like Eq. 2 allow direct application of the theory to complicated flows, since the calculations are straightforward once aoo is given.

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Correlation of fractionation tray performance via a cross‐flow boundary‐layer model

Abstract: The nonequilibrium tray model proposed by Young and Stewart ( 1990) (1983, 1991 1.

Cited by 2 publications

References 33 publications

Parameter estimation from multiresponse data

Parameter estimation from multiresponse data

Concise correlation of sieve‐tray heat and mass transfer

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