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Process Circuit Analysis 113

bubble of vapor forms. It is also the temperature at which the last bubble of vapor
condenses. Similarly, the dew-point temperature is the temperature at which the
first drop of liquid condenses or the last drop of liquid that vaporizes. Table 3.3.2
lists the equations for calculating the bubble-point temperature, and Table 3.3.3
lists the equations for calculating the dew-point temperature. These calculations do
not require mass and energy balances. We could solve this set of equations simul-
taneously in its present form, after substituting appropriate expressions for the
equations shown in functional notation.

Table 3.3.2 Summary of Equations for Calculating the Bubble-Point
Temperature_________________________________

Subscripts: Methane = 1, Propane = 2
Equilibrium Relations

y2V,lB + y2V,2B =1 (3.3.19)
K 2,iB = y 2V,iB / y 2L)iB' (3.3.20)

K2,2B = Y2V.2B / Y2L,2Br (3.3.21)
Thermodynamic Properties

K 2,iB = f(T 2 B,P 2 ') (3.3.22)

K 2, 2B = f(T 2B ,P 2 ') (3.323)

Variables

y2V,iB - y2v,2B - TB - K 2;1B - K 2)2B

Degrees of Freedom

F = 5 - 5 = 0

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