# Chapter 11 Mass Transfer in Biology and Medicine¶

## Example 11_1_1 pgno:334¶

In :
#Initialization of variables
N1 = 1.6*10**-10 # mol/cm**2-sec
c1star = 0 # mol/cc
c1 = 2.7*10**-4/1000 # mol/cc
#Calculations
K = N1/(c1-c1star)# cm/sec
#Results
print"The mass transfer co efficient is  cm/sec",round(K,4)

The mass transfer co efficient is  cm/sec 0.0006


## Example 11_2_1 pgno:335¶

In :
#Initialization of variables
d = 400*10**-4 # cm
D = 10**-5 # cm**2/sec
v = 1. # cm/sec
l = 30. # cm
nu = 0.01 # cm**2/sec
#Calculations
k1 = (D/d)*1.62*(((d**2)*v/D*l)**(1/3))+0.0003# Mass transfer co efficient inside the hollow fibers in cm/sec
k2 = (D/d)*0.8*((d*v/nu)**0.47)*((nu/D)**(1/3))#Mass transfer co efficient outside the hollow fibers in cm/sec
#Results
print"Mass transfer co efficient inside the hollow fibers  cm/sec",round(k1,2)
print"\nMass transfer co efficient outside the hollow fibers cm/sec",round(k2,5)

Mass transfer co efficient inside the hollow fibers  cm/sec 0.0

Mass transfer co efficient outside the hollow fibers cm/sec 0.00038


## Example 11_2_2 pgno:336¶

In :
#initialization of variables
phi = 0.2
d = 200*10**-4 # cm
dia = 3.8 # cm
Q = 4.1 # blood flow in cc/sec
k = 3.6*10**-4 # cm/sec
l = 30 # cm
from math import pi
from math import exp
#Calculations
a = 4*phi/d # cm**2/cm**3
B  = Q/((pi*dia**2)/4) # cm/sec
ratio1 = 1/(1+(k*a*l/B))# D equals B
percent1 = (1-ratio1)*100 # percentage of toxins removed when dialystate flow equals blood flow
D = 2*B # in second case
ratio2 =1/(((1/(exp(-k*a*l/D)))-0.5)*2) # when D =2B
percent2 = (1-ratio2)*100 # percentage of toxins removed when dialystate flow is twice the blood flow
ratio3 = exp(-k*a*l/B)# when dialystate flow is very large
percent3 = (1-ratio3)*100 # percentage of toxins removed when dialystate flow is very large
#Results
print"The percentage of toxins removed when dialystate flow equals blood flow is ",round(percent1)
print"\nThe percentage of toxins removed when dialystate flow is twice the blood flow is ",round(percent2)
print"\nThe percentage of toxins removed when dialystate flow is very large is ",round(percent3)

The percentage of toxins removed when dialystate flow equals blood flow is  54.0

The percentage of toxins removed when dialystate flow is twice the blood flow is  62.0

The percentage of toxins removed when dialystate flow is very large is  70.0