For dry gas and liquid water at 25°C, the following enthalpies are computed for the inlet- and exit-gas streams (basis, 100 kmol of gas entering):

Entering gas:

Water vapor 4(10,490) = 41,960

69,272 kcal

Exit gas (assumed saturated with water at 25°C): Acetone (2/400)(94/100)(2500) =

Water vapor

31,612 kcal

Enthalpy change of liquid = 69,272 - 31,612 = 37,660 kcal/100 kmol gas. Thus, At = ti —12 = 37,660/18Lm, and the relation between Lm/Gm and the liquidphase temperature rise is

The following table summarizes the critical values for various assumed temperature rises:

A t, °C


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