28.12 A thin polymer film contains some residual liquid solvent. It is desired to evaporate the solvent (n-hexane, solute A) from the polymer using the process shown below. Both sides of the polymer film Wet polymer film (solvont + polymer) (width = 0.5 m, length = 2,5 m) Dried polymer film wrapped into bundle (oxits drying process) Cross flow of air V- 1.50 m/s Entrance exit drying process 0.1 g solvent drying process ??g solvent XM " TOg dry polymer X " TOg dry polymer 50.0 g polymer (dry basis) are exposed to the cross flow of air. The evaporation rate of the solvent from the polymer film is limited by external convection. The dried polymer film is then rolled up into a bundle. During the drying process, the width of the thin polymer film is 0.5 m and the length of the polymer film is 2.5 m. The flowing air has a bulk velocity of 1.5 m/s, a temperature of 20°C, and the total system pressure of 1.0 atm. The wet polymer film is also maintained at 20°C. The vapor pressure of the solvent at 20°C is 0.16 atm, the diffusion coefficient of the solvent in air is 0.080 cm³/s at 20°C and 1.0 atm, and the molecular weight of the solvent is 86 g/g mol. The partial pressure of the solvent in the bulk air flow can be assumed to be near zero. The kinematic viscosity of air is 1.5 × 10-5 m²/s at 20°C. (a) Evaluate the Sc number and the average Sh number for the solvent evaporation process. (b) What is the total evaportion rate of the solvent from the 0.5 m by 2.5 m polymer film, recognizing that both sides of the film are exposed to the following air? (c) The solvent loading in the polymer film at the entrance of the drying process is 0.1 g solvent per gram of dry polymer (XAo = 0.1 g solvent/g dry polymer). The total mass flow rate of the polymer film on a solvent-free dry polymer basis is m, = 50.0 g dry polymer/s. What is the solvent loading in the polymer film exiting the drying process (Xs in g solvent/g dry polymer)?
28.12 A thin polymer film contains some residual liquid solvent. It is desired to evaporate the solvent (n-hexane, solute A) from the polymer using the process shown below. Both sides of the polymer film Wet polymer film (solvont + polymer) (width = 0.5 m, length = 2,5 m) Dried polymer film wrapped into bundle (oxits drying process) Cross flow of air V- 1.50 m/s Entrance exit drying process 0.1 g solvent drying process ??g solvent XM " TOg dry polymer X " TOg dry polymer 50.0 g polymer (dry basis) are exposed to the cross flow of air. The evaporation rate of the solvent from the polymer film is limited by external convection. The dried polymer film is then rolled up into a bundle. During the drying process, the width of the thin polymer film is 0.5 m and the length of the polymer film is 2.5 m. The flowing air has a bulk velocity of 1.5 m/s, a temperature of 20°C, and the total system pressure of 1.0 atm. The wet polymer film is also maintained at 20°C. The vapor pressure of the solvent at 20°C is 0.16 atm, the diffusion coefficient of the solvent in air is 0.080 cm³/s at 20°C and 1.0 atm, and the molecular weight of the solvent is 86 g/g mol. The partial pressure of the solvent in the bulk air flow can be assumed to be near zero. The kinematic viscosity of air is 1.5 × 10-5 m²/s at 20°C. (a) Evaluate the Sc number and the average Sh number for the solvent evaporation process. (b) What is the total evaportion rate of the solvent from the 0.5 m by 2.5 m polymer film, recognizing that both sides of the film are exposed to the following air? (c) The solvent loading in the polymer film at the entrance of the drying process is 0.1 g solvent per gram of dry polymer (XAo = 0.1 g solvent/g dry polymer). The total mass flow rate of the polymer film on a solvent-free dry polymer basis is m, = 50.0 g dry polymer/s. What is the solvent loading in the polymer film exiting the drying process (Xs in g solvent/g dry polymer)?
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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Transcribed Image Text:28.12 A thin polymer film contains some residual liquid
solvent. It is desired to evaporate the solvent (n-hexane, solute
A) from the polymer using the process shown below. Both sides
of the polymer film
Wet polymer film (solvont + polymer)
(width = 0.5 m, length = 2,5 m)
Dried polymer film
wrapped into bundle
(oxits drying process)
Cross flow of air
V- 1.50 m/s
Entrance
exit
drying
process
0.1 g solvent
drying
process
??g solvent
XM " TOg dry polymer
X " TOg dry polymer
50.0 g polymer (dry basis)
are exposed to the cross flow of air. The evaporation rate of the
solvent from the polymer film is limited by external convection.
The dried polymer film is then rolled up into a bundle. During the
drying process, the width of the thin polymer film is 0.5 m and the
length of the polymer film is 2.5 m. The flowing air has a bulk
velocity of 1.5 m/s, a temperature of 20°C, and the total system
pressure of 1.0 atm. The wet polymer film is also maintained at
20°C. The vapor pressure of the solvent at 20°C is 0.16 atm, the
diffusion coefficient of the solvent in air is 0.080 cm³/s at 20°C
and 1.0 atm, and the molecular weight of the solvent is 86 g/g
mol. The partial pressure of the solvent in the bulk air flow can be
assumed to be near zero. The kinematic viscosity of air is 1.5 ×
10-5 m²/s at 20°C.
(a) Evaluate the Sc number and the average Sh number for the
solvent evaporation process.
(b) What is the total evaportion rate of the solvent from the 0.5
m by 2.5 m polymer film, recognizing that both sides of the
film are exposed to the following air?
(c) The solvent loading in the polymer film at the entrance of
the drying process is 0.1 g solvent per gram of dry polymer
(XAo = 0.1 g solvent/g dry polymer). The total mass flow
rate of the polymer film on a solvent-free dry polymer basis
is m, = 50.0 g dry polymer/s. What is the solvent loading in
the polymer film exiting the drying process (Xs in g
solvent/g dry polymer)?
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