Condensers silver-Bell-Ghaly method

Additional corrections to hw can be made because of condensation conditions, but will not be included in this solution. With the establishment of the four temperature sections in the heat exchanger, the Silver-Bell-Ghaly method can now be used to approximate the required areas in... 

Condensers 200 Condenser Configurations 204 Design Calculation Method 205 The Silver-Bell-Ghaly Method 206... 

The basis of the method was stated by Silver (1947). A numerical solution of a condenser for mixed hydrocarbons was carried out by Webb and McNaught (in Chisholm, 1980, p. 98) comparison of the Silver-Bell-Ghaly result with a Colburn-Hougen calculation showed close agreement in this case. Bell and Ghaly (1973) claim only that their method predicts values from 0 to 100% over the correct values, always conservative. A solution with constant heat transfer coefficients is made in Example 8.11 A recent review of the subject has been presented by McNaught (in Taborek et al., 1983, p. 35). 

Empirical methods approximate methods, in which the resistance to heat transfer is considered to control the rate of condensation, and the mass transfer resistance is neglected. Design methods have been published by Silver (1947), Bell and Ghaly... 

The basic fluid dynamics and heat- and mass-transfer processes for multicomponent condensation are poorly understood, and the computation is difficult available design methods are both heuristic and feasible only for computer solution. The basic model was developed by Silver [42] and put in more general form by Bell and Ghaly [43]. Computer-based design methods that have been validated against experimental data are commercially available. 

Equilibrium methods, as proposed originally by Silver [200] and extended by Bell and Ghaly [201] and others, all assume that there is local equilibrium between the vapor and the condensate throughout the condenser. Even though condensation is a nonequilibrium process, the gas temperature Tg is assumed to follow a vapor-liquid equilibrium curve at T, as the vapor mixture is cooled from the mixture dew point 7"dew to the mixture bubble temperature Tbub. These methods therefore require the generation of a cooling or condensation curve (not to be confused with the condensation curve described in Fig. 14.1), as shown in Fig. 14.25,... 

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